U.S. patent application number 17/454611 was filed with the patent office on 2022-05-19 for radio frequency (rf) exposure compliance.
The applicant listed for this patent is QUALCOMM Incorporated. Invention is credited to Paul GUCKIAN, Lin LU, Jagadish NADAKUDUTI, Reza SHAHIDI.
Application Number | 20220159581 17/454611 |
Document ID | / |
Family ID | |
Filed Date | 2022-05-19 |
United States Patent
Application |
20220159581 |
Kind Code |
A1 |
LU; Lin ; et al. |
May 19, 2022 |
RADIO FREQUENCY (RF) EXPOSURE COMPLIANCE
Abstract
Certain aspects of the present disclosure provide techniques and
apparatus for determining a transmit power based on a pattern
and/or future conditions for a transmission while maintaining radio
frequency (RF) exposure compliance. An example method generally
includes obtaining a pattern associated with one or more first
transmissions, determining a transmit power for one or more second
transmissions based at least in part on the pattern and an RF
exposure limit, and transmitting the one or more second
transmissions at the determined transmit power.
Inventors: |
LU; Lin; (San Diego, CA)
; NADAKUDUTI; Jagadish; (Mission Viejo, CA) ;
GUCKIAN; Paul; (La Jolla, CA) ; SHAHIDI; Reza;
(San Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM Incorporated |
San Diego |
CA |
US |
|
|
Appl. No.: |
17/454611 |
Filed: |
November 11, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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63175464 |
Apr 15, 2021 |
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63152773 |
Feb 23, 2021 |
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63141834 |
Jan 26, 2021 |
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63113488 |
Nov 13, 2020 |
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International
Class: |
H04W 52/22 20060101
H04W052/22 |
Claims
1. An apparatus for wireless communication, comprising: a memory;
and a processor coupled to the memory, the processor and the memory
being configured to: obtain a pattern associated with one or more
first transmissions, determine a transmit power for one or more
second transmissions based at least in part on the pattern and a
radio frequency (RF) exposure limit, and transmit the one or more
second transmissions at the determined transmit power.
2. The apparatus of claim 1, wherein the pattern includes at least
one of: a transmit power pattern; an antenna usage pattern; a user
behavior pattern; a transmission type; a priority pattern; an
application pattern; an application type; a wireless network
pattern; or a sensor information.
3. The apparatus of claim 1, wherein the processor and the memory
are further configured to: determine a first transmit power;
determine a second transmit power based at least in part on average
transmitted power over a time interval; select a third transmit
power as a minimum of the first transmit power and the second
transmit power; and determine the transmit power for the one or
more second transmissions such that the transmit power is less than
or equal to the third transmit power.
4. The apparatus of claim 3, wherein the second transmit power is
based at least in part on a reciprocal of a normalized average
transmitted power in a past time interval.
5. The apparatus of claim 1, wherein the processor and the memory
are further configured to: determine a first transmit power for
each of a plurality of radios; determine a second transmit power
for each of the plurality of radios, wherein the second transmit
power is based at least in part on a normalized average transmitted
power for the respective radio over a time interval; select a third
transmit power for each of the plurality of radios as a minimum of
the first transmit power and the second transmit power for the
respective radio; and determine the transmit power for the one or
more second transmissions such that the transmit power for each of
the plurality of radios is less than or equal to the third transmit
power for the respective radio.
6. The apparatus of claim 5, wherein the processor and the memory
are further configured to: determine a fourth transmit power based
at least in part on a product between a maximum average power
corresponding to the RF exposure limit for the respective radio and
a reciprocal of a sum of minimums of a normalized average
transmitted power for the plurality of radios and unity, wherein
the fourth transmit power is further based on a proportion between
the normalized average transmitted power for the respective radio
and a total of the normalized average transmitted powers for the
plurality of radios; determine a fifth transmit power that is the
maximum average power corresponding to the RF exposure limit
divided by a number of the plurality of radios; and select the
second transmit power based on a maximum of the fourth transmit
power and the fifth transmit power.
7. The apparatus of claim 5, wherein the processor and the memory
are further configured to: adjust the time interval for the
normalized average transmitted power based at least in part on an
average power over a time window corresponding to the RF exposure
limit; and select, as the time interval, a maximum among a first
time interval and a second time interval varying with average
transmitted power over a past time window, wherein the first time
interval and the second time interval depend on a transmission
frequency of the one or more second transmissions.
8. The apparatus of claim 5, wherein the processor and the memory
are further configured to adjust the time interval for the
normalized average transmitted power based at least in part on one
or more current network conditions.
9. The apparatus of claim 1, wherein the processor and the memory
are further configured to: determine a first transmit power; apply
a cap to the first transmit power to determine a second transmit
power; and determine the transmit power for the one or more second
transmissions such that the transmit power is less than or equal to
the second transmit power.
10. The apparatus of claim 1, wherein the processor and the memory
are further configured to: determine a first transmit power for the
one or more second transmissions based at least in part on a
time-averaged RF exposure in a past time window; determine a second
transmit power based at least in part on a normalized average
transmitted power for a radio over a time interval; determine a
third transmit power that is a maximum average power corresponding
to the RF exposure limit; select a fourth transmit power as a
minimum of the first transmit power and the second transmit power
for the radio; select a fifth transmit power as a minimum of the
first transmit power and the third transmit power for the radio;
select a sixth transmit power among the first transmit power, the
fourth transmit power, and the fifth transmit power; and determine
the transmit power for the one or more second transmissions such
that the transmit power is less than or equal to the sixth transmit
power for the radio.
11. The apparatus of claim 1, wherein the processor and the memory
are further configured to: determine a first transmit power for
each of a plurality of radios, wherein the first transmit power is
based at least in part on a time-averaged RF exposure in a past
time window; determine a second transmit power for each of the
plurality of radios, wherein the second transmit power is based at
least in part on a normalized average transmitted power for the
respective radio over a time interval; determine a third transmit
power for each of the plurality of radios, wherein the third
transmit power is a maximum average power corresponding to the RF
exposure limit divided by a number of the plurality of radios;
select a fourth transmit power for each of the plurality of radios
as a minimum of the first transmit power and the second transmit
power for the respective radio; select a fifth transmit power for
each of the plurality of radios as a minimum of the first transmit
power and the third transmit power for the respective radio; select
a sixth transmit power for each of the plurality of radios among
the first transmit power, the fourth transmit power, and the fifth
transmit power for the respective radio; and determine the transmit
power for the one or more second transmissions such that the
transmit power for each of the plurality of radios is less than or
equal to the sixth transmit power for the respective radio.
12. The apparatus of claim 2, wherein the processor and the memory
are further configured to: determine an overall available RF
exposure margin based on a usage pattern for each radio among a
plurality of radios; allocate an RF exposure margin to each of the
radios based on the overall available RF exposure margin; determine
a transmit power ceiling for one of the radios based on the usage
pattern for each of the other radios; and determine the transmit
power for the one or more second transmissions based at least in
part on the transmit power ceiling and the RF exposure margin
allocated to the one of the radios.
13. The apparatus of claim 2, wherein the processor and the memory
are further configured to: determine a transmit power ceiling for a
radio based on a usage pattern for a radio; and determine the
transmit power for the one or more second transmissions based at
least in part on the transmit power ceiling, wherein the transmit
power ceiling is less than a maximum transmit power supported by
the apparatus and greater than an average power limit associated
with the RF exposure limit.
14. The apparatus of claim 12, wherein the usage pattern for each
radio among the plurality of radios comprises an average
transmitted power in a past time interval associated with the
respective radio.
15. The apparatus of claim 12, wherein the processor and the memory
are further configured to determine, as the overall available RF
exposure margin, a difference of a maximum available usage and a
sum of the usage patterns for the radios.
16. The apparatus of claim 15, wherein the processor and the memory
are further configured to: allocate a proportion of the overall
available RF exposure margin to each of the radios as the RF
exposure margin for the respective radio; allocate the proportion
of the overall available RF exposure margin to each of the radios
based at least in part on a priority associated with at least one
of the radios; and determine, as the transmit power ceiling, a
difference of the maximum available usage and a sum of the usage
patterns for each of the other radios.
17. The apparatus of claim 16, wherein at least one of a priority
or the proportion of the overall available RF exposure margin is
associated with at least one of a frequency band, an application, a
service, a network condition, or an exposure scenario associated
with the at least one of the radios.
18. The apparatus of claim 12, wherein the processor and the memory
are further configured to determine the transmit power such that
the transmit power is less than or equal to a minimum of the
transmit power ceiling and the RF exposure margin allocated to the
one of the radios.
19. The apparatus of claim 12, wherein the processor and the memory
are further configured to adjust the transmit power ceiling in
response to a change in the usage pattern for the radios.
20. The apparatus of claim 2, wherein the processor and the memory
are further configured to: determine the application type for the
one or more second transmissions; and determine the transmit power
based on the application type having priority over other
application types.
21. The apparatus of claim 1, wherein the processor and the memory
are further configured to determine the transmit power with machine
learning based at least in part on the pattern.
22. The apparatus of claim 21, wherein the processor and the memory
are further configured to: generate at least one of upcoming user
behavior or upcoming network conditions with machine learning; and
determine the transmit power based on at least one of the upcoming
user behavior, current user behavior, the upcoming network
conditions, or current network conditions.
23. The apparatus of claim 1, wherein the processor and the memory
are further configured to: correlate the pattern to a transmit time
associated with the one or more second transmissions; compare the
transmit time to a time window associated with the RF exposure
limit; and determine the transmit power based on the
comparison.
24. The apparatus of claim 2, wherein: the transmit power pattern
includes one or more transmit powers over one or more time windows
associated with the RF exposure limit; the antenna usage pattern
includes a usage pattern for each radio among a plurality of
radios; the user behavior pattern includes one or more times
associated with when a user uses the apparatus for wireless
communications; the application pattern includes at least one of
one or more transmit times or one or more transmit powers
associated with one or more applications; the application type
indicates a kind of application that generates data for
transmission; the wireless network pattern includes at least one
of: a channel quality between the apparatus and a receiving entity;
a modulation and coding scheme (MCS) associated with the one or
more first transmissions; a coding rate associated with the one or
more first transmissions; a periodicity associated with the one or
more first transmissions; a duty cycle associated with the one or
more first transmissions; or an indication of the apparatus's
mobility during the one or more first transmissions; the sensor
information includes at least one of an indication of the
apparatus's proximity to a non-human object, an indication that the
apparatus is in free space, an indication of a user usage scenario,
an indication of a usage state of the apparatus, or an indication
of when antenna switching occurs at the apparatus; and the user
usage scenario indicates to which portion of a user's body the
apparatus is in proximity.
25. The apparatus of claim 1, wherein the RF exposure limit
comprises a specific absorption rate (SAR) limit, a power density
(PD) limit, or a combination thereof.
26. A method of wireless communication by a wireless device,
comprising: obtaining a pattern associated with one or more first
transmissions; determining a transmit power for one or more second
transmissions based at least in part on the pattern and a radio
frequency (RF) exposure limit; and transmitting the one or more
second transmissions at the determined transmit power.
27. The method of claim 26, wherein the pattern includes at least
one of: a transmit power pattern; an antenna usage pattern; a user
behavior pattern; a transmission type; a priority pattern; an
application pattern; an application type; a wireless network
pattern; or a sensor information.
28. The method of claim 26, wherein determining the transmit power
comprises: determining a first transmit power for each of a
plurality of radios; determining a second transmit power for each
of the plurality of radios, wherein the second transmit power is
based at least in part on a normalized average transmitted power
for the respective radio over a time interval; selecting a third
transmit power for each of the plurality of radios as a minimum of
the first transmit power and the second transmit power for the
respective radio; and determining the transmit power for the one or
more second transmissions such that the transmit power for each of
the plurality of radios is less than or equal to the third transmit
power for the respective radio.
29. The method of claim 27, wherein determining the transmit power
comprises: determining an overall available RF exposure margin
based on a usage pattern for each radio among a plurality of
radios; allocating an RF exposure margin to each of the radios
based on the overall available RF exposure margin; determining a
transmit power ceiling for one of the radios based on the usage
pattern for each of the other radios; and determining the transmit
power for the one or more second transmissions based at least in
part on the transmit power ceiling and the RF exposure margin
allocated to the one of the radios.
30. The method of claim 27, wherein determining the transmit power
comprises: determining a transmit power ceiling for a radio based
on a usage pattern for a radio; and determining the transmit power
for the one or more second transmissions based at least in part on
the transmit power ceiling, wherein the transmit power ceiling is
less than a maximum transmit power supported by the wireless device
and greater than an average power limit associated with the RF
exposure limit.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present Application for Patent claims priority to U.S.
Provisional Application No. 63/113,488, filed Nov. 13, 2020; U.S.
Provisional Application No. 63/141,834, filed Jan. 26, 2021; U.S.
Provisional Application No. 63/152,773, filed Feb. 23, 2021; and
U.S. Provisional Application No. 63/175,464, filed Apr. 15, 2021,
each of which is hereby expressly incorporated by reference herein
in its entirety.
BACKGROUND
Field of the Disclosure
[0002] Aspects of the present disclosure relate to wireless
communications, and more particularly, to determining a transmit
power while maintaining radio frequency (RF) exposure
compliance.
Description of Related Art
[0003] Wireless communication systems are widely deployed to
provide various telecommunication services such as telephony,
video, data, messaging, broadcasts, etc. Modern wireless
communication devices (such as cellular telephones) are generally
mandated to meet radio frequency (RF) exposure limits set by
domestic and international standards and regulations. To ensure
compliance with the standards, such devices currently undergo an
extensive certification process prior to being shipped to market.
To ensure that a wireless communication device complies with an RF
exposure limit, techniques have been developed to enable the
wireless communication device to assess RF exposure from the
wireless communication device and adjust the transmission power of
the wireless communication device accordingly to comply with the RF
exposure limit.
SUMMARY
[0004] The systems, methods, and devices of the disclosure each
have several aspects, no single one of which is solely responsible
for its desirable attributes. Without limiting the scope of this
disclosure as expressed by the claims which follow, some features
will now be discussed briefly. After considering this discussion,
and particularly after reading the section entitled "Detailed
Description" one will understand how the features of this
disclosure provide advantages that include desirable transmit
powers in compliance with radio frequency (RF) exposure limits.
[0005] Certain aspects of the subject matter described in this
disclosure can be implemented in a method of wireless communication
by a user equipment (UE). The method generally includes obtaining a
pattern associated with one or more first transmissions;
determining a transmit power for one or more second transmissions
based at least in part on the pattern and an RF exposure limit; and
transmitting the one or more second transmissions at the determined
transmit power.
[0006] Certain aspects of the subject matter described in this
disclosure can be implemented in an apparatus for wireless
communication. The apparatus generally includes a memory, a
processor, and a transmitter. The processor is coupled to the
memory, such that the processor and the memory are configured to
obtain a pattern associated with one or more first transmissions,
and determine a transmit power for one or more second transmissions
based at least in part on the pattern and an RF exposure limit; and
a transmitter configured to transmit the one or more second
transmissions at the determined transmit power.
[0007] Certain aspects of the subject matter described in this
disclosure can be implemented in an apparatus for wireless
communication. The apparatus generally includes means for obtaining
a pattern associated with one or more first transmissions; means
for determining a transmit power for one or more second
transmissions based at least in part on the pattern and an RF
exposure limit; and means for transmitting the one or more second
transmissions at the determined transmit power.
[0008] Certain aspects of the subject matter described in this
disclosure can be implemented in a computer-readable medium having
instructions stored thereon for obtaining a pattern associated with
one or more first transmissions; determining a transmit power for
one or more second transmissions based at least in part on the
pattern and an RF exposure limit; and transmitting the one or more
second transmissions at the determined transmit power.
[0009] Certain aspects of the subject matter described in this
disclosure can be implemented in an apparatus for wireless
communication. The apparatus generally includes a memory and a
processor coupled to the memory. The processor and the memory are
configured to obtain a pattern associated with one or more first
transmissions, determine a transmit power for one or more second
transmissions based at least in part on the pattern and a radio
frequency (RF) exposure limit, and transmit the one or more second
transmissions at the determined transmit power.
[0010] Certain aspects of the subject matter described in this
disclosure can be implemented in an apparatus for wireless
communication. The apparatus generally includes a memory and a
processor coupled to the memory. The processor and the memory are
configured to obtain data for a transmission to a receiving entity
and radio conditions associated with the transmission, determine a
transmit time associated with the data based at least in part on
the radio conditions, and transmit, to the receiving entity, a
signal indicative of the data at a transmit power based at least in
part on the determined transmit time and a radio frequency (RF)
exposure limit.
[0011] Certain aspects of the subject matter described in this
disclosure can be implemented in an apparatus for wireless
communication. The apparatus generally includes a memory and a
processor coupled to the memory. The processor and the memory are
configured to select a transmission mode from a plurality of
transmission modes based on data for a transmission from the
apparatus to a receiving entity and one or more radio conditions
associated with the transmission, and transmit, to the receiving
entity, a signal indicative of the data at a transmit power based
at least in part on the selected transmission mode and a radio
frequency (RF) exposure limit.
[0012] Certain aspects of the subject matter described in this
disclosure can be implemented in an apparatus for wireless
communication. The apparatus generally includes obtaining data for
a transmission to a receiving entity and radio conditions
associated with the transmission; determining a transmit time
associated with the data based at least in part on the radio
conditions; and transmitting, to the receiving entity, a signal
indicative of the data at a transmit power based at least in part
on the determined transmit time and a radio frequency (RF) exposure
limit.
[0013] Certain aspects of the subject matter described in this
disclosure can be implemented in an apparatus for wireless
communication. The apparatus generally includes selecting a
transmission mode from a plurality of transmission modes based on
data for a transmission from the wireless device to a receiving
entity and one or more radio conditions associated with the
transmission; and transmitting, to the receiving entity, a signal
indicative of the data at a transmit power based at least in part
on the selected transmission mode and a radio frequency (RF)
exposure limit.
[0014] Certain aspects of the subject matter described in this
disclosure can be implemented in a computer-readable medium having
instructions stored thereon for obtaining data for a transmission
to a receiving entity and radio conditions associated with the
transmission; determining a transmit time associated with the data
based at least in part on the radio conditions; and transmitting,
to the receiving entity, a signal indicative of the data at a
transmit power based at least in part on the determined transmit
time and a radio frequency (RF) exposure limit.
[0015] Certain aspects of the subject matter described in this
disclosure can be implemented in a computer-readable medium having
instructions stored thereon for selecting a transmission mode from
a plurality of transmission modes based on data for a transmission
from the wireless device to a receiving entity and one or more
radio conditions associated with the transmission; and
transmitting, to the receiving entity, a signal indicative of the
data at a transmit power based at least in part on the selected
transmission mode and a radio frequency (RF) exposure limit.
[0016] Certain aspects of the subject matter described in this
disclosure can be implemented in a method of wireless communication
by a wireless device. The method generally includes obtaining data
for a transmission to a receiving entity and radio conditions
associated with the transmission; determining a transmit time
associated with the data based at least in part on the radio
conditions; and transmitting, to the receiving entity, a signal
indicative of the data at a transmit power based at least in part
on the determined transmit time and a radio frequency (RF) exposure
limit.
[0017] Certain aspects of the subject matter described in this
disclosure can be implemented in a method of wireless communication
by a wireless device. The method generally includes selecting a
transmission mode from a plurality of transmission modes based on
data for a transmission from the wireless device to a receiving
entity and one or more radio conditions associated with the
transmission; and transmitting, to the receiving entity, a signal
indicative of the data at a transmit power based at least in part
on the selected transmission mode and a radio frequency (RF)
exposure limit.
[0018] To the accomplishment of the foregoing and related ends, the
one or more aspects comprise the features hereinafter fully
described and particularly pointed out in the claims. The following
description and the appended drawings set forth in detail certain
illustrative features of the one or more aspects. These features
are indicative, however, of but a few of the various ways in which
the principles of various aspects may be employed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] So that the manner in which the above-recited features of
the present disclosure can be understood in detail, a more
particular description, briefly summarized above, may be had by
reference to aspects, some of which are illustrated in the
drawings. It is to be noted, however, that the appended drawings
illustrate only certain typical aspects of this disclosure and are
therefore not to be considered limiting of its scope, for the
description may admit to other equally effective aspects.
[0020] FIG. 1 is a block diagram conceptually illustrating an
example wireless communication network, in accordance with certain
aspects of the present disclosure.
[0021] FIG. 2 is a block diagram conceptually illustrating a design
of an example base station (BS) and user equipment (UE), in
accordance with certain aspects of the present disclosure.
[0022] FIG. 3 is a block diagram of an example radio frequency (RF)
transceiver, in accordance with certain aspects of the present
disclosure.
[0023] FIG. 4 is a diagram illustrating an example of a normalized
specific absorption rate (SAR) distribution combined with a
normalized power density (PD) distribution, in accordance with
certain aspects of the present disclosure.
[0024] FIGS. 5A, 5B, and 5C are graphs illustrating examples of
transmit powers over time in compliance with an RF exposure limit,
in accordance with certain aspects of the present disclosure.
[0025] FIG. 6 is a flow diagram illustrating example operations for
wireless communication, in accordance with certain aspects of the
present disclosure.
[0026] FIGS. 7A, 7B, 8A, 8B, and 9A are graphs illustrating example
patterns used to determine one or more transmit powers over time,
in accordance with certain aspects of the present disclosure.
[0027] FIG. 9B is a graph illustrating applying a transmit power
ceiling based on a pattern depicted in FIG. 9A, in accordance with
certain aspects of the present disclosure.
[0028] FIGS. 10A and 10B are flow diagrams illustrating example
operations for wireless communication, in accordance with certain
aspects of the present disclosure.
[0029] FIGS. 11A-C are graphs 1100A-1100C of transmit powers over
time (P(t)) illustrating a time-average mode that uses a dynamic
reserve power, in accordance with certain aspects of the present
disclosure
[0030] FIG. 12 illustrates a communications device (e.g., a UE)
that may include various components configured to perform
operations for the techniques disclosed herein, in accordance with
certain aspects of the present disclosure.
[0031] To facilitate understanding, identical reference numerals
have been used, where possible, to designate identical elements
that are common to the figures. It is contemplated that elements
disclosed in one aspect may be beneficially utilized on other
aspects without specific recitation.
DETAILED DESCRIPTION
[0032] Aspects of the present disclosure provide apparatus,
methods, processing systems, and computer-readable mediums for
ensuring radio frequency (RF) exposure compliance based on one or
more patterns and/or future conditions.
[0033] In certain cases, time-averaging of RF exposure may be
performed to be in compliance with the RF exposure limit within a
specified time window. Multi-mode/multi-band wireless communication
devices have multiple transmit antennas, which may be configured to
simultaneously transmit in one or more sub-6 GHz bands and/or one
or more bands greater than 6 GHz, such as mmWave (e.g., FR2) or FR3
bands. As described herein, the RF exposure of sub-6 GHz bands may
be evaluated in terms of specific absorption rate (SAR), whereas
the RF exposure of bands greater than 6 GHz may be evaluated in
terms of power density (PD). Due to the regulations on simultaneous
exposure, the wireless communication device may limit maximum
transmit power for sub-6 GHz bands and/or bands greater than 6
GHz.
[0034] Aspects of the present disclosure provide enhanced
techniques for ensuring RF exposure compliance, for example, based
on one or more patterns and/or future conditions. The patterns may
include a transmit power pattern (e.g., the instantaneous
transmission power as a function of time) associated with past
transmissions over the course of various time periods (such as the
past few minutes, hour(s), or day(s)) and/or an application pattern
indicative of the periodic bursts of traffic that an application
(e.g., a voice or video call application) may generate. In certain
aspects, the pattern may be used to identify when an upcoming
transmission will occur, and the pattern may be correlated to
various characteristics associated with the upcoming transmission,
such as transmit times, transmit power over time, antenna
switching, network conditions, sensor information, etc.
[0035] As an example, if the pattern indicates that the transmit
time of the upcoming transmission is likely to be relatively long
(e.g., the transmit time is greater than the time window associated
with the RF exposure limit) and/or that a consistent uplink
transmission is likely to be maintained over the time window, then
the transmitter may allocate a lower power level (e.g., P.sub.limit
where P.sub.limit<P.sub.max) to the upcoming transmission. If
the pattern indicates that the transmit time of the upcoming
transmission is likely to be relatively short (e.g., the transmit
time is less than the time window associated with the RF exposure
limit) and/or that transmission is likely to be non-continuous
(e.g., bursts and/or gaps are likely), then the transmitter may
allocate a higher instantaneous power (e.g., higher than
P.sub.limit) to the upcoming transmission in compliance with the RF
exposure limit.
[0036] In certain aspects, the UE may consider future conditions
(such as transmit time and/or radio conditions) in determining the
transmit power for RF exposure compliance. Aspects of the present
disclosure provide techniques and apparatus for switching between
various transmission modes (e.g., as described herein) based on a
transmit time associated with data and/or radio conditions while
ensuring RF exposure compliance. In certain aspects, the transmit
time may be derived from a size (e.g., a data buffer size)
associated with the data and a current data rate. As an example, if
the data buffer size is large (e.g., the transmit time is greater
than the time window associated with the RF exposure limit), then
the transmitter may operate in a peak mode to enable continuous
transmission at the maximum average power level (e.g.,
P.sub.limit). If the data buffer size is small (e.g., the transmit
time is less than the time window associated with the RF exposure
limit), then the transmitter may operate in a time-average mode and
transmit at the maximum power to complete the transmission if a
reserve power margin is sufficient for high power transmission. The
transmit time may be determined based on the data buffer size and
the radio conditions. For example, a signal or communications
environment may limit or be indicative of a throughput or amount of
data which can be transmitted at an instantaneous time or over a
certain upcoming amount of time. In some aspects, the determined
transmit time may be based on actual or measured values. For
example, the radio conditions may be determined based on a measured
RSRP. In some aspects, the determined transmit time may be based on
predicted values, for example based on one or more patterns. For
example, the radio conditions may be determined based on path loss
a user is likely to experience at a time of day or in a certain
location as indicated by a pattern.
[0037] The various techniques described herein for ensuring RF
exposure compliance may enable desirable transmit powers for data
transmissions. The desirable transmit power may provide desirable
uplink/sidelink performance, such as desirable data rates, carrier
aggregation, and/or a connection at the edge of a cell.
[0038] The following description provides examples of RF exposure
compliance in communication systems, and is not limiting of the
scope, applicability, or examples set forth in the claims. Changes
may be made in the function and arrangement of elements discussed
without departing from the scope of the disclosure. Various
examples may omit, substitute, or add various procedures or
components as appropriate. For instance, the methods described may
be performed in an order different from that described, and various
steps may be added, omitted, or combined. Also, features described
with respect to some examples may be combined in some other
examples. For example, an apparatus may be implemented or a method
may be practiced using any number of the aspects set forth herein.
In addition, the scope of the disclosure is intended to cover such
an apparatus or method which is practiced using other structure,
functionality, or structure and functionality in addition to, or
other than, the various aspects of the disclosure set forth herein.
It should be understood that any aspect of the disclosure disclosed
herein may be embodied by one or more elements of a claim. The word
"exemplary" is used herein to mean "serving as an example,
instance, or illustration." Any aspect described herein as
"exemplary" is not necessarily to be construed as preferred or
advantageous over other aspects.
[0039] In general, any number of wireless networks may be deployed
in a given geographic area. Each wireless network may support a
particular radio access technology (RAT) and may operate on one or
more frequencies. A RAT may also be referred to as a radio
technology, an air interface, etc. A frequency may also be referred
to as a carrier, a subcarrier, a frequency channel, a tone, a
subband, etc. Each frequency may support a single RAT in a given
geographic area in order to avoid interference between wireless
networks of different RATs, or may support multiple RATs.
[0040] The techniques described herein may be used for various
wireless networks and radio technologies. While aspects may be
described herein using terminology commonly associated with 3G, 4G,
and/or new radio (e.g., 5G NR) wireless technologies, aspects of
the present disclosure can be applied in other generation-based
communication systems and/or to wireless technologies such as
802.11, 802.15, etc.
[0041] NR access may support various wireless communication
services, such as enhanced mobile broadband (eMBB) targeting wide
bandwidth (e.g., 80 MHz or beyond), millimeter wave (mmWave)
targeting high carrier frequency (e.g., 24 GHz to 53 GHz or
beyond), massive machine type communications MTC (mMTC) targeting
non-backward compatible MTC techniques, and/or mission critical
targeting ultra-reliable low-latency communications (URLLC). These
services may have specific latency and reliability settings. These
services may also have different transmission time intervals (TTIs)
to meet respective quality of service (QoS) settings. In addition,
these services may coexist in the same subframe. NR supports
beamforming, and beam direction may be dynamically configured.
Multiple-input, multiple-output (MIMO) transmissions with precoding
may also be supported, as may multi-layer transmissions.
Aggregation of multiple cells may be supported.
[0042] FIG. 1 illustrates an example wireless communication network
100 in which aspects of the present disclosure may be performed.
For example, the wireless communication network 100 may be an NR
system (e.g., a 5G NR network), an Evolved Universal Terrestrial
Radio Access (E-UTRA) system (e.g., a 4G network), a Universal
Mobile Telecommunications System (UMTS) (e.g., a 2G/3G network), or
a code division multiple access (CDMA) system (e.g., a 2G/3G
network), or may be configured for communications according to an
IEEE standard such as one or more of the 802.11 standards, etc.
[0043] As illustrated in FIG. 1, the wireless communication network
100 may include a number of BSs 110a-z (each also individually
referred to herein as BS 110 or collectively as BSs 110) and other
network entities. A BS 110 may provide communication coverage for a
particular geographic area, sometimes referred to as a "cell,"
which may be stationary or may move according to the location of a
mobile BS 110. In some examples, the BSs 110 may be interconnected
to one another and/or to one or more other BSs or network nodes
(not shown) in wireless communication network 100 through various
types of backhaul interfaces (e.g., a direct physical connection, a
wireless connection, a virtual network, or the like) using any
suitable transport network. In the example shown in FIG. 1, the BSs
110a, 110b and 110c may be macro BSs for the macro cells 102a, 102b
and 102c, respectively. The BS 110x may be a pico BS for a pico
cell 102x. The BSs 110y and 110z may be femto BSs for the femto
cells 102y and 102z, respectively. ABS may support one or multiple
cells.
[0044] The BSs 110 communicate with UEs 120a-y (each also
individually referred to herein as UE 120 or collectively as UEs
120) in the wireless communication network 100. As shown in FIG. 1,
the UE 120a includes an RF exposure manager 122 that determines
transmit powers for transmissions to a receiving entity (such as BS
110a or another UE 120) based on various patterns and/or future
conditions, in accordance with aspects of the present disclosure.
The UEs 120 (e.g., 120x, 120y, etc.) may be dispersed throughout
the wireless communication network 100, and each UE 120 may be
stationary or mobile. Wireless communication network 100 may also
include relay stations (e.g., relay station 110r), also referred to
as relays or the like, that receive a transmission of data and/or
other information from an upstream station (e.g., a BS 110a or a UE
120r) and send a transmission of the data and/or other information
to a downstream station (e.g., a UE 120 or a BS 110), or that relay
transmissions between UEs 120, to facilitate communication between
devices.
[0045] A network controller 130 may be in communication with a set
of BSs 110 and provide coordination and control for these BSs 110
(e.g., via a backhaul). In certain cases, the network controller
130 may include a centralized unit (CU) and/or a distributed unit
(DU), for example, in a 5G NR system. In aspects, the network
controller 130 may be in communication with a core network 132
(e.g., a 5G Core Network (5GC)), which provides various network
functions such as Access and Mobility Management, Session
Management, User Plane Function, Policy Control Function,
Authentication Server Function, Unified Data Management,
Application Function, Network Exposure Function, Network Repository
Function, Network Slice Selection Function, etc.
[0046] Another wireless device in the wireless communication
network 100 may alternatively or additionally include an RF
exposure manager. For example, one or more of the BSs 110 may be
configured as a customer premises equipment (CPE), and an RF
exposure manager configured as described herein may be implemented
in a BS or CPE.
[0047] FIG. 2 illustrates example components of BS 110a and UE 120a
(e.g., the wireless communication network 100 of FIG. 1), which may
be used to implement aspects of the present disclosure.
[0048] At the BS 110a, a transmit processor 220 may receive data
from a data source 212 and control information from a
controller/processor 240. The control information may be for the
physical broadcast channel (PBCH), physical control format
indicator channel (PCFICH), physical hybrid ARQ indicator channel
(PHICH), physical downlink control channel (PDCCH), group common
PDCCH (GC PDCCH), etc. The data may be for the physical downlink
shared channel (PDSCH), etc. A medium access control (MAC)-control
element (MAC-CE) is a MAC layer communication structure that may be
used for control command exchange between wireless nodes. The
MAC-CE may be carried in a shared channel such as a physical
downlink shared channel (PDSCH), a physical uplink shared channel
(PUSCH), or a physical sidelink shared channel (PSSCH).
[0049] The processor 220 may process (e.g., encode and symbol map)
the data and control information to obtain data symbols and control
symbols, respectively. The transmit processor 220 may also generate
reference symbols, such as for the primary synchronization signal
(PSS), secondary synchronization signal (SSS), PBCH demodulation
reference signal (DMRS), and channel state information reference
signal (CSI-RS). A transmit (TX) multiple-input multiple-output
(MIMO) processor 230 may perform spatial processing (e.g.,
precoding) on the data symbols, the control symbols, and/or the
reference symbols, if applicable, and may provide output symbol
streams to the modulators (MODs) in transceivers 232a-232t. Each
modulator in the transceivers 232a-232t may process a respective
output symbol stream (e.g., for OFDM, etc.) to obtain an output
sample stream. Each of the transceivers 232a-232t may further
process (e.g., convert to analog, amplify, filter, and upconvert)
the output sample stream to obtain a downlink signal. Downlink
signals from the transceivers 232a-232t may be transmitted via the
antennas 234a-234t, respectively.
[0050] At the UE 120a, the antennas 252a-252r may receive the
downlink signals from the BS 110a and may provide received signals
to the demodulators (DEMODs) in transceivers 254a-254r,
respectively. Each of the transceivers 254a-254r may condition
(e.g., filter, amplify, downconvert, and digitize) a respective
received signal to obtain input samples. Each demodulator in
transceivers 254a-254r may further process the input samples (e.g.,
for OFDM, etc.) to obtain received symbols. A MIMO detector 256 may
obtain received symbols from all the demodulators in transceivers
254a-254r, perform MIMO detection on the received symbols if
applicable, and provide detected symbols. A receive processor 258
may process (e.g., demodulate, deinterleave, and decode) the
detected symbols, provide decoded data for the UE 120a to a data
sink 260, and provide decoded control information to a
controller/processor 280.
[0051] On the uplink, at UE 120a, a transmit processor 264 may
receive and process data (e.g., for the physical uplink shared
channel (PUSCH)) from a data source 262 and control information
(e.g., for the physical uplink control channel (PUCCH) from the
controller/processor 280. The transmit processor 264 may also
generate reference symbols for a reference signal (e.g., for the
sounding reference signal (SRS)). The symbols from the transmit
processor 264 may be precoded by a TX MIMO processor 266 if
applicable, further processed by the modulators (MODs) and other
components in transceivers 254a-254r (e.g., for SC-FDM, etc.), and
transmitted to the BS 110a. At the BS 110a, the uplink signals from
the UE 120a may be received by the antennas 234, processed by the
modulators and other components in transceivers 232a-232t, detected
by a MIMO detector 236 if applicable, and further processed by a
receive processor 238 to obtain decoded data and control
information sent by the UE 120a. The receive processor 238 may
provide the decoded data to a data sink 239 and the decoded control
information to the controller/processor 240.
[0052] The memories 242 and 282 may store data and program codes
for BS 110a and UE 120a, respectively. A scheduler 244 may schedule
UEs for data transmission on the downlink and/or uplink.
[0053] Antennas 252, processors 266, 258, 264, and/or
controller/processor 280 of the UE 120a and/or antennas 234,
processors 220, 230, 238, and/or controller/processor 240 of the BS
110a may be used to perform the various techniques and methods
described herein. As shown in FIG. 2, the controller/processor 280
of the UE 120a has an RF exposure manager 281 that determines
transmit powers for transmissions to a receiving entity (such as BS
110a) based on various patterns and/or future conditions, according
to aspects described herein. Although shown at the
controller/processor, other components of the UE 120a and BS 110a
may be used to perform the operations described herein.
[0054] NR may utilize orthogonal frequency division multiplexing
(OFDM) with a cyclic prefix (CP) on the uplink and downlink. NR may
support half-duplex operation using time division duplexing (TDD).
OFDM and single-carrier frequency division multiplexing (SC-FDM)
partition the system bandwidth into multiple orthogonal
subcarriers, which are also commonly referred to as tones, bins,
etc. Each subcarrier may be modulated with data. Modulation symbols
may be sent in the frequency domain with OFDM and in the time
domain with SC-FDM. The spacing between adjacent subcarriers may be
fixed, and the total number of subcarriers may be dependent on the
system bandwidth. The system bandwidth may also be partitioned into
subbands. For example, a subband may cover multiple resource blocks
(RBs).
[0055] While the UE 120a is described with respect to FIGS. 1 and 2
as communicating with a BS and/or within a network, the UE 120a may
be configured to communicate directly with/transmit directly to
another UE 120, or with/to another wireless device without relaying
communications through a network. In some aspects, the BS 110a
illustrated in FIG. 2 and described above is an example of another
UE 120.
Example RF Transceiver
[0056] FIG. 3 is a block diagram of an example RF transceiver
circuit 300, which may be used in any of the wireless devices
described above, in accordance with certain aspects of the present
disclosure. The RF transceiver circuit 300 includes at least one
transmit (TX) path 302 (also known as a transmit chain) for
transmitting signals via one or more antennas 306 and at least one
receive (RX) path 304 (also known as a receive chain) for receiving
signals via the antennas 306. When the TX path 302 and the RX path
304 share an antenna 306, the paths may be connected with the
antenna via an interface 308, which may include any of various
suitable RF devices, such as a switch, a duplexer, a diplexer, a
multiplexer, and the like.
[0057] Receiving in-phase (I) or quadrature (Q) baseband analog
signals from a digital-to-analog converter (DAC) 310, the TX path
302 may include a baseband filter (BBF) 312, a mixer 314, a driver
amplifier (DA) 316, and a power amplifier (PA) 318. The BBF 312,
the mixer 314, and the DA 316 may be included in one or more radio
frequency integrated circuits (RFICs). The PA 318 may be external
to the RFIC(s) for some implementations.
[0058] The BBF 312 filters the baseband signals received from the
DAC 310, and the mixer 314 mixes the filtered baseband signals with
a transmit local oscillator (LO) signal to convert the baseband
signal of interest to a different frequency (e.g., upconvert from
baseband to a radio frequency). This frequency conversion process
produces the sum and difference frequencies between the LO
frequency and the frequencies of the baseband signal of interest.
The sum and difference frequencies are referred to as the beat
frequencies. The beat frequencies are typically in the RF range,
such that the signals output by the mixer 314 are typically RF
signals, which may be amplified by the DA 316 and/or by the PA 318
before transmission by the antenna 306. While one mixer 314 is
illustrated, several mixers may be used to upconvert the filtered
baseband signals to one or more intermediate frequencies and to
thereafter upconvert the intermediate frequency signals to a
frequency for transmission.
[0059] The RX path 304 may include a low noise amplifier (LNA) 324,
a mixer 326, and a baseband filter (BBF) 328. The LNA 324, the
mixer 326, and the BBF 328 may be included in one or more RFICs,
which may or may not be the same RFIC that includes the TX path
components. RF signals received via the antenna 306 may be
amplified by the LNA 324, and the mixer 326 mixes the amplified RF
signals with a receive local oscillator (LO) signal to convert the
RF signal of interest to a different baseband frequency (e.g.,
downconvert). The baseband signals output by the mixer 326 may be
filtered by the BBF 328 before being converted by an
analog-to-digital converter (ADC) 330 to digital I or Q signals for
digital signal processing.
[0060] Some systems may employ frequency synthesizers with a
voltage-controlled oscillator (VCO) to generate a stable, tunable
LO with a particular tuning range. Thus, the transmit LO may be
produced by a TX frequency synthesizer 320, which may be buffered
or amplified by amplifier 322 before being mixed with the baseband
signals in the mixer 314. Similarly, the receive LO may be produced
by an RX frequency synthesizer 332, which may be buffered or
amplified by amplifier 334 before being mixed with the RF signals
in the mixer 326.
[0061] A controller 336 may direct the operation of the RF
transceiver circuit 300, such as transmitting signals via the TX
path 302 and/or receiving signals via the RX path 304. The
controller 336 may be a processor, a digital signal processor
(DSP), an application specific integrated circuit (ASIC), a field
programmable gate array (FPGA) or other programmable logic device
(PLD), discrete gate or transistor logic, discrete hardware
components, or any combination thereof. The memory 338 may store
data and program codes for operating the RF transceiver circuit
300. The controller 336 and/or memory 338 may include control
logic. In certain cases, the controller 336 may determine
time-averaged RF exposure measurements based on transmission power
levels applied to the TX path 302 (e.g., certain levels of gain at
the PA 318) to set a transmit power level that complies with an RF
exposure limit set by domestic/foreign regulations and/or
international standards as further described herein.
Example RF Exposure Compliance
[0062] RF exposure may be expressed in terms of a specific
absorption rate (SAR), which measures energy absorption by human
tissue per unit mass and may have units of watts per kilogram
(W/kg). RF exposure may also be expressed in terms of power density
(PD), which measures energy absorption per unit area and may have
units of mW/cm.sup.2. In certain cases, a maximum permissible
exposure (MPE) limit in terms of PD may be imposed for wireless
communication devices using transmission frequencies above 6 GHz.
The MPE limit is a regulatory metric for exposure based on area,
e.g., an energy density limit defined as a number, X, watts per
square meter (W/m.sup.2) averaged over a defined area and
time-averaged over a frequency-dependent time window in order to
prevent a human exposure hazard represented by a tissue temperature
change.
[0063] SAR may be used to assess RF exposure for transmission
frequencies less than 6 GHz, which cover wireless communication
technologies such as 2G/3G (e.g., CDMA), 4G (e.g., LTE), 5G (e.g.,
NR in 6 GHz bands), IEEE 802.11ac, etc. PD may be used to assess RF
exposure for transmission frequencies higher than 10 GHz, which
cover wireless communication technologies such as IEEE 802.11ad,
802.11ay, 5G in mmWave bands, etc. Thus, different metrics may be
used to assess RF exposure for different wireless communication
technologies.
[0064] A wireless communication device (e.g., UE 120) may
simultaneously transmit signals using multiple wireless
communication technologies. For example, the wireless communication
device may simultaneously transmit signals using a first wireless
communication technology operating at or below 6 GHz (e.g., 3G, 4G,
5G, etc.) and a second wireless communication technology operating
above 6 GHz (e.g., mmWave 5G in 24 to 60 GHz bands, IEEE 802.11ad
or 802.11 ay). In certain aspects, the wireless communication
device may simultaneously transmit signals using the first wireless
communication technology (e.g., 3G, 4G, 5G in sub-6 GHz bands, IEEE
802.11 ac, etc.) in which RF exposure is measured in terms of SAR,
and the second wireless communication technology (e.g., 5G in 24 to
60 GHz bands, IEEE 802.11ad, 802.11ay, etc.) in which RF exposure
is measured in terms of PD.
[0065] To assess RF exposure from transmissions using the first
technology (e.g., 3G, 4G, 5G in sub-6 GHz bands, IEEE 802.11ac,
etc.), the wireless communication device may include multiple SAR
distributions for the first technology stored in memory (e.g.,
memory 282 of FIG. 2 or memory 338 of FIG. 3). Each of the SAR
distributions may correspond to a respective one of multiple
transmit scenarios supported by the wireless communication device
for the first technology. The transmit scenarios may correspond to
various combinations of antennas (e.g., antennas 252a through 252r
of FIG. 2 or antenna 306 of FIG. 3), frequency bands, channels
and/or body positions, as discussed further below. In some
examples, one or more of the SAR distributions include a single
value (e.g., a peak value determined based on the description
below, or a sum of peak values).
[0066] The SAR distribution (also referred to as a SAR map) for
each transmit scenario may be generated based on measurements
(e.g., E-field measurements) performed in a test laboratory using a
model of a human body. After the SAR distributions are generated,
the SAR distributions are stored in the memory to enable a
processor (e.g., processor 280 of FIG. 2 or controller 336 of FIG.
3) to assess RF exposure in real time, as discussed further below.
Each SAR distribution may include a set of SAR values, where each
SAR value may correspond to a different location (e.g., on the
model of the human body). Each SAR value may comprise a SAR value
averaged over a mass of 1 g or 10 g at the respective location.
[0067] The SAR values in each SAR distribution correspond to a
particular transmission power level (e.g., the transmission power
level at which the SAR values were measured in the test
laboratory). Since SAR scales with transmission power level, the
processor may scale a SAR distribution for any transmission power
level by multiplying each SAR value in the SAR distribution by the
following transmission power scaler:
T .times. x c T .times. x SAR ( 1 ) ##EQU00001##
where Tx.sub.c is a current transmission power level for the
respective transmit scenario, and Tx.sub.SAR is the transmission
power level corresponding to the SAR values in the stored SAR
distribution (e.g., the transmission power level at which the SAR
values were measured in the test laboratory).
[0068] As discussed above, the wireless communication device may
support multiple transmit scenarios for the first technology. In
certain aspects, the transmit scenarios may be specified by a set
of parameters. The set of parameters may include one or more of the
following: an antenna parameter indicating one or more antennas
used for transmission (i.e., active antennas), a frequency band
parameter indicating one or more frequency bands used for
transmission (i.e., active frequency bands), a channel parameter
indicating one or more channels used for transmission (i.e., active
channels), a body position parameter indicating the location of the
wireless communication device relative to the user's body location
(head, trunk, away from the body, etc.), and/or other parameters.
In cases where the wireless communication device supports a large
number of transmit scenarios, it may be very time-consuming and
expensive to perform measurements for each transmit scenario in a
test setting (e.g., test laboratory). To reduce test time,
measurements may be performed for a subset of the transmit
scenarios to generate SAR distributions for the subset of transmit
scenarios. In this example, the SAR distribution for each of the
remaining transmit scenarios may be generated by combining two or
more of the SAR distributions for the subset of transmit scenarios,
as discussed further below.
[0069] For example, SAR measurements may be performed for each one
of the antennas to generate a SAR distribution for each one of the
antennas. In this example, a SAR distribution for a transmit
scenario in which two or more of the antennas are active may be
generated by combining the SAR distributions for the two or more
active antennas.
[0070] In another example, SAR measurements may be performed for
each one of multiple frequency bands to generate a SAR distribution
for each one of the multiple frequency bands. In this example, a
SAR distribution for a transmit scenario in which two or more
frequency bands are active may be generated by combining the SAR
distributions for the two or more active frequency bands.
[0071] In certain aspects, a SAR distribution may be normalized
with respect to a SAR limit by dividing each SAR value in the SAR
distribution by the SAR limit. In this case, a normalized SAR value
exceeds the SAR limit when the normalized SAR value is greater than
one, and is below the SAR limit when the normalized SAR value is
less than one. In these aspects, each of the SAR distributions
stored in the memory may be normalized with respect to a SAR
limit.
[0072] In certain aspects, the normalized SAR distribution for a
transmit scenario may be generated by combining two or more
normalized SAR distributions. For example, a normalized SAR
distribution for a transmit scenario in which two or more antennas
are active may be generated by combining the normalized SAR
distributions for the two or more active antennas. For the case in
which different transmission power levels are used for the active
antennas, the normalized SAR distribution for each active antenna
may be scaled by the respective transmission power level before
combining the normalized SAR distributions for the active antennas.
The normalized SAR distribution for simultaneous transmission from
multiple active antennas may be given by the following:
S .times. A .times. R norm .times. .times. _ .times. .times.
combined = i = 1 i = K .times. T .times. x i T .times. x S .times.
A .times. R .times. i S .times. A .times. R i S .times. A .times. R
lim ( 2 ) ##EQU00002##
where SAR.sub.lim is a SAR limit, SAR.sub.norm_combined is the
combined normalized SAR distribution for simultaneous transmission
from the active antennas, i is an index for the active antennas,
SARI is the SAR distribution for the i.sup.th active antenna,
Tx.sub.i is the transmission power level for the i.sup.th active
antenna, Tx.sub.SARi is the transmission power level for the SAR
distribution for the i.sup.th active antenna, and K is the number
of the active antennas.
[0073] Equation (2) may be rewritten as follows:
S .times. A .times. R norm .times. .times. _ .times. .times.
combined = i = 1 i = K .times. T .times. x i T .times. x S .times.
A .times. R .times. i SAR norm .times. .times. _ .times. .times. i
( 3 .times. a ) ##EQU00003##
where SAR.sub.norm_i is the normalized SAR distribution for the
i.sup.th active antenna. In the case of simultaneous transmissions
using multiple active antennas at the same transmitting frequency
(e.g., multiple in multiple out (MIMO)), the combined normalized
SAR distribution is obtained by summing the square root of the
individual normalized SAR distributions and computing the square of
the sum, as given by the following:
S .times. A .times. R norm .times. .times. _ .times. .times.
combined .times. .times. _ .times. .times. MIMO = [ i = 1 i = K
.times. T .times. x i T .times. x S .times. A .times. R .times. i
SAR norm .times. .times. _ .times. .times. i ] 2 . ( 3 .times. b )
##EQU00004##
[0074] In another example, normalized SAR distributions for
different frequency bands may be stored in the memory. In this
example, a normalized SAR distribution for a transmit scenario in
which two or more frequency bands are active may be generated by
combining the normalized SAR distributions for the two or more
active frequency bands. For the case where the transmission power
levels are different for the active frequency bands, the normalized
SAR distribution for each of the active frequency bands may be
scaled by the respective transmission power level before combining
the normalized SAR distributions for the active frequency bands. In
this example, the combined SAR distribution may also be computed
using Equation (3a) in which i is an index for the active frequency
bands, SAR.sub.norm_i is the normalized SAR distribution for the
i.sup.th active frequency band, Tx.sub.i is the transmission power
level for the i.sup.th active frequency band, and Tx.sub.SARi is
the transmission power level for the normalized SAR distribution
for the i.sup.th active frequency band.
[0075] To assess RF exposure from transmissions using the second
technology (e.g., 5G in 24 to 60 GHz bands, IEEE 802.11ad,
802.11ay, etc.), the wireless communication device may include
multiple PD distributions for the second technology stored in the
memory (e.g., memory 282 of FIG. 2 or memory 338 of FIG. 3). Each
of the PD distributions may correspond to a respective one of
multiple transmit scenarios supported by the wireless communication
device for the second technology. The transmit scenarios may
correspond to various combinations of antennas (e.g., antennas 252a
through 252r of FIG. 2 or antenna 306 of FIG. 3), frequency bands,
channels and/or body positions, as discussed further below. In some
examples, one or more of the PD distributions include a single
value (e.g., a peak value determined based on the description
below, or a sum of peak values).
[0076] The PD distribution (also referred to as PD map) for each
transmit scenario may be generated based on measurements (e.g.,
E-field measurements) performed in a test laboratory using a model
of a human body. After the PD distributions are generated, the PD
distributions are stored in the memory to enable the processor
(e.g., processor 280 of FIG. 2 or controller 336 of FIG. 3) to
assess RF exposure in real time, as discussed further below. Each
PD distribution may include a set of PD values, where each PD value
may correspond to a different location (e.g., on the model of the
human body).
[0077] The PD values in each PD distribution correspond to a
particular transmission power level (e.g., the transmission power
level at which the PD values were measured in the test laboratory).
Since PD scales with transmission power level, the processor may
scale a PD distribution for any transmission power level by
multiplying each PD value in the PD distribution by the following
transmission power scaler:
T .times. x c T .times. x P .times. D ( 4 ) ##EQU00005##
where Tx.sub.c is a current transmission power level for the
respective transmit scenario, and Tx.sub.PD is the transmission
power level corresponding to the PD values in the PD distribution
(e.g., the transmission power level at which the PD values were
measured in the test laboratory).
[0078] As discussed above, the wireless communication device may
support multiple transmit scenarios for the second technology. In
certain aspects, the transmit scenarios may be specified by a set
of parameters. The set of parameters may include one or more of the
following: an antenna parameter indicating one or more antennas
used for transmission (i.e., active antennas), a frequency band
parameter indicating one or more frequency bands used for
transmission (i.e., active frequency bands), a channel parameter
indicating one or more channels used for transmission (i.e., active
channels), a body position parameter indicating the location of the
wireless communication device relative to the user's body location
(head, trunk, away from the body, etc.), and/or other parameters.
In cases where the wireless communication device supports a large
number of transmit scenarios, it may be very time-consuming and
expensive to perform measurements for each transmit scenario in a
test setting (e.g., test laboratory). To reduce test time,
measurements may be performed for a subset of the transmit
scenarios to generate PD distributions for the subset of transmit
scenarios. In this example, the PD distribution for each of the
remaining transmit scenarios may be generated by combining two or
more of the PD distributions for the subset of transmit scenarios,
as discussed further below.
[0079] For example, PD measurements may be performed for each one
of the antennas to generate a PD distribution for each one of the
antennas. In this example, a PD distribution for a transmit
scenario in which two or more of the antennas are active may be
generated by combining the PD distributions for the two or more
active antennas.
[0080] In another example, PD measurements may be performed for
each one of multiple frequency bands to generate a PD distribution
for each one of the multiple frequency bands. In this example, a PD
distribution for a transmit scenario in which two or more frequency
bands are active may be generated by combining the PD distributions
for the two or more active frequency bands.
[0081] In certain aspects, a PD distribution may be normalized with
respect to a PD limit by dividing each PD value in the PD
distribution by the PD limit. In this case, a normalized PD value
exceeds the PD limit when the normalized PD value is greater than
one, and is below the PD limit when the normalized PD value is less
than one. In these aspects, each of the PD distributions stored in
the memory may be normalized with respect to a PD limit.
[0082] In certain aspects, the normalized PD distribution for a
transmit scenario may be generated by combining two or more
normalized PD distributions. For example, a normalized PD
distribution for a transmit scenario in which two or more antennas
are active may be generated by combining the normalized PD
distributions for the two or more active antennas. For the case in
which different transmission power levels are used for the active
antennas, the normalized PD distribution for each active antenna
may be scaled by the respective transmission power level before
combining the normalized PD distributions for the active antennas.
The normalized PD distribution for simultaneous transmission from
multiple active antennas may be given by the following:
P .times. D norm .times. .times. _ .times. .times. combined = i = 1
i = L .times. T .times. x i T .times. x P .times. D .times. i P
.times. D i P .times. D lim ( 5 ) ##EQU00006##
where PD.sub.lim is a PD limit, PD.sub.norm_combined is the
combined normalized PD distribution for simultaneous transmission
from the active antennas, i is an index for the active antennas,
PD.sub.i is the PD distribution for the i.sup.th active antenna,
Tx.sub.i is the transmission power level for the i.sup.th active
antenna, Tx.sub.PDi is the transmission power level for the PD
distribution for the i.sup.th active antenna, and L is the number
of the active antennas.
[0083] Equation (5) may be rewritten as follows:
P .times. D norm .times. .times. _ .times. .times. combined = i = 1
i = L .times. T .times. x i T .times. x P .times. D .times. i PD
norm .times. .times. _ .times. .times. i ( 6 .times. a )
##EQU00007##
where PD.sub.norm_i is the normalized PD distribution for the
i.sup.th active antenna. In the case of simultaneous transmissions
using multiple active antennas at the same transmitting frequency
(e.g., MIMO), the combined normalized PD distribution is obtained
by summing the square root of the individual normalized PD
distributions and computing the square of the sum, as given by the
following:
P .times. D norm .times. .times. _ .times. .times. combined .times.
.times. _ .times. .times. MIMO = [ i = 1 i = L .times. T .times. x
i T .times. x P .times. D .times. i PD norm .times. .times. _
.times. .times. i ] 2 . ( 6 .times. b ) ##EQU00008##
[0084] In another example, normalized PD distributions for
different frequency bands may be stored in the memory. In this
example, a normalized PD distribution for a transmit scenario in
which two or more frequency bands are active may be generated by
combining the normalized PD distributions for the two or more
active frequency bands. For the case where the transmission power
levels are different for the active frequency bands, the normalized
PD distribution for each of the active frequency bands may be
scaled by the respective transmission power level before combining
the normalized PD distributions for the active frequency bands. In
this example, the combined PD distribution may also be computed
using Equation (6a) in which i is an index for the active frequency
bands, PD.sub.norm_i is the normalized PD distribution for the
i.sup.th active frequency band, Tx.sub.i is the transmission power
level for the i.sup.th active frequency band, and Tx.sub.PDi is the
transmission power level for the normalized PD distribution for the
i.sup.th active frequency band.
[0085] As discussed above, the UE 120 may simultaneously transmit
signals using the first technology (e.g., 3G, 4G, IEEE 802.11ac,
etc.) and the second technology (e.g., 5G, IEEE 802.11ad, etc.), in
which RF exposure is measured using different metrics for the first
technology and the second technology (e.g., SAR for the first
technology and PD for the second technology). In this case, the
processor 280 may determine a first maximum allowable power level
for the first technology and a second maximum allowable power level
for the second technology for transmissions in a future time slot
that comply with RF exposure limits. During the future time slot,
the transmission power levels for the first and second technologies
are constrained (i.e., bounded) by the determined first and second
maximum allowable power levels, respectively, to ensure compliance
with RF exposure limits, as further below. In the present
disclosure, the term "maximum allowable power level" refers to a
"maximum allowable power level" imposed by an RF exposure limit
unless stated otherwise. It is to be appreciated that the "maximum
allowable power level" is not necessarily equal to the absolute
maximum power level that complies with an RF exposure limit and may
be less than the absolute maximum power level that complies with
the RF exposure limit (e.g., to provide a safety margin). The
"maximum allowable power level" may be used to set a power level
limit on a transmission at a transmitter such that the power level
of the transmission is not allowed to exceed the "maximum allowable
power level" to ensure RF exposure compliance.
[0086] The processor 280 may determine the first and second maximum
allowable power levels as follows. The processor may determine a
normalized SAR distribution for the first technology at a first
transmission power level, determine a normalized PD distribution
for the second technology at a second transmission power level, and
combine the normalized SAR distribution and the normalized PD
distribution to generate a combined normalized RF exposure
distribution (referred to simply as a combined normalized
distribution below). The value at each location in the combined
normalized distribution may be determined by combining the
normalized SAR value at the location with the normalized PD value
at the location or another technique.
[0087] The processor 280 may then determine whether the first and
second transmission power levels comply with RF exposure limits by
comparing the peak value in the combined normalized distribution
with one. If the peak value is equal to or less than one (i.e.,
satisfies the condition.ltoreq.1), then the processor 280 may
determine that the first and second transmission power levels
comply with RF exposure limits (e.g., SAR limit and PD limit) and
use the first and second transmission power levels as the first and
second maximum allowable power levels, respectively, during the
future time slot. If the peak value is greater than one, then the
processor 280 may determine that the first and second transmission
power levels do not comply with RF exposure limits. The condition
for RF exposure compliance for simultaneous transmissions using the
first and second technologies may be given by:
SAR.sub.norm+PD.sub.norm.ltoreq.1 (7).
[0088] FIG. 4 is a diagram illustrating the normalized SAR
distribution 410 and the normalized PD distribution 420, in which
the normalized SAR distribution 410 and the normalized PD
distribution 420 are combined to generate a combined normalized
distribution 430. FIG. 4 also shows the condition that the peak
value in the combined normalized distribution 430 be equal to or
less than one for RF exposure compliance. Although each of the
distributions 410, 420, and 430 is depicted as a two-dimensional
distribution in FIG. 4, it is to be appreciated that the present
disclosure is not limited to this example.
[0089] The normalized SAR distribution in Equation (7) may be
generated by combining two or more normalized SAR distributions as
discussed above (e.g., for a transmit scenario using multiple
active antennas). Similarly, the normalized PD distribution in
Equation (7) may be generated by combining two or more normalized
PD distributions as discussed above (e.g., for a transmit scenario
using multiple active antennas). In this case, the condition for RF
exposure compliance in Equation (7) may be rewritten using
Equations (3a) and (6a) as follows:
i = 1 i = K .times. T .times. x i T .times. x S .times. A .times. R
.times. i SAR norm .times. .times. _ .times. .times. i + i = 1 i =
L .times. T .times. x i T .times. x P .times. D .times. i PD norm
.times. .times. _ .times. .times. i .ltoreq. 1 . ( 8 )
##EQU00009##
For the MIMO case, Equations (3b) and (6b) may be combined instead.
As shown in Equation (8), the combined normalized distribution may
be a function of transmission power levels for the first technology
and transmission power levels for the second technology. All the
points in the combined normalized distribution may meet the
normalized limit of one in Equation (8). Additionally, when
combining SAR and PD distributions, the SAR and PD distributions
may be aligned spatially or aligned with their peak locations so
that the combined distribution given by Equation (8) represents
combined RF exposure for a given position of a human body.
[0090] In certain cases, the transmitter may ensure RF exposure
compliance by operating under one of the following example schemes:
(a) "a reserve-less time-average mode" without a reserve margin
that allows for dropped connections during the time window, (b) "a
peak mode" as described herein with respect to FIG. 5B, or (c) "a
time-average mode," as described herein with respect to FIG.
5C.
[0091] In certain cases, time-averaging of RF exposure may be
performed to be in compliance with the RF exposure limit within a
specified time window (T) (e.g., 2 seconds for 60 GHz bands, 100 or
360 seconds for bands .ltoreq.6 GHz, etc.) associated with the RF
exposure limit. For example, FIG. 5A is a graph 500A of a transmit
power over time (P(t)) that varies over the time window (T)
associated with the RF exposure limit, in accordance with certain
aspects of the present disclosure. As an example, the instantaneous
transmit power may exceed a maximum time-averaged transmit power
level P.sub.limit in certain transmission occasions in the time
window (T). That is, the transmit power may be greater than the
maximum time-averaged transmit power level P.sub.limit. In certain
cases, the UE may transmit at P.sub.max, which is the maximum
transmit power supported by the UE. In certain cases, the UE may
transmit at a transmit power less than or equal to the maximum
time-averaged transmit power level P.sub.limit in certain
transmission occasions. The maximum time-averaged transmit power
level P.sub.limit represents the time-averaged threshold for the RF
exposure limit in terms of transmit power, and in certain cases,
P.sub.limit may be referred to as the maximum time-averaged power
level or limit, or maximum average transmit power level. The graph
500A also illustrates gaps between transmission bursts, where the
gaps represent periods during which no transmission was sent from
the device.
[0092] In certain cases, the transmit power may be maintained at
the maximum average transmit power level (e.g., P.sub.limit)
allowed for RF exposure compliance that enables continuous
transmission during the time window. For example, FIG. 5B is a
graph 500B of a transmit power over time (P(t)) illustrating an
example where the transmit power is limited to P.sub.limit, in
accordance with certain aspects of the present disclosure. As
shown, the UE can transmit continuously at P.sub.limit in
compliance with the RF exposure limit.
[0093] FIG. 5C is a graph 500C of a transmit power over time (P(t))
illustrating a time-average mode that provides a reserve power
margin to enable a continuous transmission within the time window
(T), in accordance with certain aspects of the present disclosure.
As shown, the transmit power may be backed off from the maximum
instantaneous power (P.sub.max) to a reserve power (P.sub.reserve)
before the transmitter would be turned off to reserve enough
transmit power margin (e.g., difference between P.sub.limit and
P.sub.reserve) so that the UE can continue transmitting at the
lower power (P.sub.reserve) to maintain a continuous transmission
during the time window (e.g., maintain a radio connection with a
receiving entity). In some aspects, P.sub.reserve is set at a
minimum power used to maintain a link or at such minimum power plus
a margin. The transmit duration at P.sub.max may be referred to as
the burst transmit time (or high power duration). When more margin
is available in the future (after T seconds), the transmitter may
be allowed to transmit at a higher power again (e.g., in short
bursts at P.sub.max).
[0094] In the time-average mode, P.sub.max and P.sub.reserve time
durations may be controlled by a processor or control logic to
ensure the time-averaged power does not exceed P.sub.limit in the
time window. In some aspects, the UE may transmit at a power that
is higher than the average power level, but less than P.sub.max in
the time-average mode illustrated in FIG. 5C. While a single
transmit burst is illustrated in FIG. 5C, it will be understood
that the UE may instead utilize a plurality of transmit bursts
within the time window (T), for example, as described herein with
respect to FIG. 5A, where the transmit bursts are separated by
periods during which the transmit power is maintained at or below
P.sub.reserve. Further, it will be understood that the transmit
power of each transmit burst may vary (either within the burst
and/or in comparison to other bursts), and that at least a portion
of the burst may be transmitted at a power above the maximum
average power level (e.g., P.sub.limit).
[0095] While FIGS. 5A-5C illustrate continuous transmission over a
window, occasion, burst, etc., it will be understood that a duty
cycle for transmission may be implemented. In such implementations,
a transmit power may be zero periodically and maintained at a
higher level (e.g., a level as illustrated in FIGS. 5A-5C) during
other portions of the duty cycle.
[0096] In certain aspects, the burst transmit time of P(t) at
P.sub.max calculated for a given P.sub.max, P.sub.limit,
P.sub.reserve and T, can be scaled depending on a duty cycle of the
transmission to a receiving entity. For example, the burst transmit
time may be adjusted by a factor associated with the duty cycle
(1/duty_cycle), where duty_cycle is between [0, 1]. As used herein,
the duty cycle of the transmission may refer to a portion of a
specific period in which the transmission is scheduled or
allocated. In aspects, the period associated with the burst
transmit time may be independent of the time window (T) used for RF
exposure compliance. In certain cases, the duty cycle may be
standardized (e.g., predetermined) with a specific RAT and/or vary
over time, for example, due to changes in radio conditions,
mobility, and/or user behavior. In some examples, the duty cycle is
determined by a base station (e.g., gNB) and communicated to a UE).
With a 100% duty cycle, the UE may be assumed to be scheduled for
continuous transmission, which may result in the transmit power
depicted in FIG. 5B. In another example, suppose the duration of
the burst transmit time is less than the time window and the period
of the burst transmit time is greater than the time window such
that a single pulse of the burst transmit time is active (or
occurs) in the time window. The transmitter may increase the burst
transmit time at P.sub.max due to there being no transmission
during a portion of the time window (e.g., P(t) can go to zero for
a portion of the time window).
[0097] Example Transmission-Pattern-Based RE Exposure
Compliance
[0098] Multi-mode/multi-band UEs have multiple transmit antennas,
which may be configured to simultaneously transmit in one or more
sub-6 GHz bands and/or one or more bands greater than 6 GHz, such
as mmWave bands. As described herein, the RF exposure of sub-6 GHz
bands may be evaluated in terms of SAR, whereas the RF exposure of
bands greater than 6 GHz may be evaluated in terms of PD. Due to
the regulations on simultaneous exposure, the wireless
communication device may limit maximum transmit power for sub-6 GHz
bands and/or bands greater than 6 GHz.
[0099] Aspects of the present disclosure provide techniques for
ensuring RF exposure compliance based on one or more patterns. The
patterns may include a transmit power pattern associated with past
transmissions over the course of various time periods (such as the
past several minutes, hour(s), or day(s)) and/or an application
pattern indicative of the periodic bursts of traffic that an
application (e.g., a voice or video call application) may generate
and/or indicative of the particular application or type of
application which is transmitting. In certain aspects, the pattern
may be used to identify when an upcoming transmission will occur,
and the pattern may be correlated to various characteristics
associated with the upcoming transmission, such as transmit times,
transmit power over time, antenna switching, network conditions,
sensor information, etc.
[0100] As an example, if the pattern indicates that the transmit
time of the upcoming transmission is most likely relatively long
(e.g., the transmit time is greater than the time window associated
with the RF exposure limit) and/or that a consistent uplink
transmission may be maintained over the time window, then the
transmitter may allocate a lower power level (e.g., P.sub.limit
where P.sub.limit<P.sub.max) to the upcoming transmission. If
the pattern indicates that the transmit time of the upcoming
transmission is most likely relatively short (e.g., the transmit
time is less than the time window associated with the RF exposure
limit) and/or that transmission is likely to be non-continuous
(e.g., bursts and/or gaps are likely), then the transmitter may
allocate a high instantaneous power (e.g., higher than P.sub.limit
and/or less than or equal to P.sub.max) to the upcoming
transmission (e.g., to at least one of the bursts), yet still
remain in compliance with the RF exposure limit.
[0101] The various techniques described herein for ensuring RF
exposure compliance may enable desirable transmit powers for data
transmissions. The desirable transmit power may provide desirable
uplink/sidelink performance, such as desirable data rates, carrier
aggregation, and/or a connection at the edge of a cell.
[0102] FIG. 6 is a flow diagram illustrating example operations 600
for wireless communication, in accordance with certain aspects of
the present disclosure. The operations 600 may be performed, for
example, by a UE (e.g., the UE 120a in the wireless communication
network 100). The operations 600 may be implemented as software
components that are executed and run on one or more processors
(e.g., controller/processor 280 of FIG. 2). Further, the
transmission of signals by the UE in the operations 600 may be
enabled, for example, by one or more antennas (e.g., antennas 252
of FIG. 2). In certain aspects, the transmission and/or reception
of signals by the UE may be implemented via a bus interface of one
or more processors (e.g., controller/processor 280) obtaining
and/or outputting signals.
[0103] The operations 600 may begin, at block 602, where the UE may
obtain a pattern associated with one or more first transmissions.
For example, the UE may obtain a transmit power pattern indicative
of transmit powers over time (such as the past few minutes,
hour(s), or day(s)) associated with past transmissions sent by the
UE. As used herein, a "pattern" generally refers to characteristics
of the first transmissions, which may be past transmissions or
samples thereof, and/or characteristics of a transmitter in the
absence of the first transmissions, for example, when the pattern
is representative of no uplink or sidelink traffic. That is, the
pattern may be associated with a transmitter additionally or
alternatively to the first transmissions. The characteristics may
include, for example, indications of transmit power over time,
network conditions over time, user behavior over time, application
type over time, application behavior over time, whether voice
and/or data is being transmitted over time, type of data being
transmitted over time, priority or class of transmissions over
time, antenna usage over time, sensor information over time, etc.
In certain aspects, the pattern may include a periodic signature of
characteristics over time, such as an indication that past
transmissions had a periodicity. In some aspects, certain patterns
may be interpreted as a "fingerprint" which is indicative of a
certain environment in which the UE is located or of a certain
scenario/user condition for the UE.
[0104] At block 604, the UE may determine a transmit power for one
or more second transmissions based at least in part on the pattern
and an RF exposure limit. As further described herein, the UE may
correlate the pattern to an upcoming transmission, transmit time
associated with the upcoming transmission, transmit power for the
upcoming transmission, and/or a transmit power limit associated
with the RF exposure limit. For example, the transmit power pattern
may indicate that the UE transmitted in periodic bursts at certain
time periods during the day. When an upcoming transmission aligns
with the periodicity of the past bursts, the UE may determine the
transmit power for the upcoming transmission based on the pattern
associated with the past bursts. In certain aspects, the UE may
periodically store the pattern (e.g., in the memory 282, or in
memory which is tightly coupled with the processor 280 or modem) as
characteristics in memory and retrieve the pattern for determining
the transmit power at block 604.
[0105] In some aspects, the determined transmit power is at or near
P.sub.limit unless it is determined based on the pattern obtained
in block 602 that additional RF exposure margin is likely to be
available. If the UE determines that additional margin is likely to
be available, the UE may determine a transmit power which is higher
than P.sub.limit (e.g., up to P.sub.max). Determining to transmit
at the higher transmit power may further be based one or more other
factors or patterns. For example, the higher transmission power may
be used when margin is likely to be available and it is further
determined that the UE is at a cell edge or likely to travel to
such an area, or margin is likely to be available and information
having a higher priority is being transmitted. In some aspects,
defaulting to a transmit power at or near P.sub.limit and
selectively increasing the transmit power may increase the
likelihood that transmissions are sent at P.sub.limit (which may,
e.g., increase throughput and/or reliability) and/or reduce the
amount of time during which transmissions are sent at a lower or
backed-off power (for example, to comply with an exposure limit).
At block 604, the UE may determine a transmission mode (e.g., as
described with respect to FIGS. 5A-5C), and the transmit power may
be determined to be at or near (e.g., lower than) P.sub.limit, or
higher than P.sub.limit (e.g., increased above P.sub.limit), based
on and/or in compliance with the determined transmission mode.
[0106] At block 606, the UE may transmit the one or more second
transmissions at the determined transmit power. For example, the UE
may transmit, to a base station (e.g., BS 110a), transmissions at
the determined transmit power. In certain cases, the UE may
transmit to another UE via a sidelink channel.
[0107] The pattern at blocks 602, 604 may include one or more
patterns associated with the first transmissions. In aspects, the
pattern may include at least one of a transmit power pattern, a
user behavior pattern, an antenna usage pattern, an application
type, an application pattern, a wireless network pattern, a
transmission type or priority pattern, or sensor information, among
other types of information and/or patterns. The transmit power
pattern may include transmit powers over time (e.g. instantaneous
transmit power as a function of time), for example, over a certain
time window or over a collection of time windows. In certain cases,
if the averaged power from a transmit power pattern is greater than
or equal to a determined threshold (e.g., a threshold less than or
equal to P.sub.limit), then the UE may limit the power to a lower
power level (e.g., P.sub.limit or lower) at all times. Otherwise,
the UE may allow higher instantaneous transmit powers
(>P.sub.limit) within the time window. That is, the averaged
power from the transmit power pattern may indicate how to determine
the transmit power for the second transmissions. As an example,
suppose the averaged power from the transmit power pattern is less
than half of the average transmit power level (e.g., P.sub.limit).
This may indicate that the UE is likely to transmit very little
uplink or sidelink traffic presently and/or in the near future, and
the transmit power may be safely increased to be in compliance with
the RF exposure limit. In certain cases, the transmit power pattern
may indicate the duration of transmissions, and the durations may
be used to determine the transmit power. For example, if the
transmit power pattern indicates that the transmit time of the
upcoming transmission is likely to be relatively long (e.g., the
transmit time is likely greater than the time window associated
with the RF exposure limit) and/or that a consistent uplink
transmission likely can be maintained over the time window, then
the transmitter may allocate a lower power level (e.g., P.sub.limit
where P.sub.limit<P.sub.max) to the upcoming transmission.
[0108] For certain aspects, the time window used for determining
the pattern may be separate from another time window (e.g., the
time window (T) in FIGS. 5A and 5B) associated with the RF exposure
limit. For example, the time window used for the pattern may
include information regarding transmissions which were prior to a
time window that is being used to calculate a current RF exposure.
In aspects, such prior information may have preceded the window
being used to calculate the current RF exposure by a number of
seconds, multiple minutes or hours, or several days or more. In
aspects, the time window for the transmit power pattern may have a
duration that is the same or different from the time window
associated with the current RF exposure limit. The transmit power
pattern may include one or more transmit powers over one or more
time windows associated with the RF exposure limit. As an example,
the time window for the transmit power pattern may have a duration
of one or more seconds, one or more minutes, one or more hours, or
one or more days. The UE may use the transmit power pattern
associated with past transmissions to identify when upcoming
(future) transmissions will occur, and the UE may determine the
transmit power for the upcoming transmissions based on the transmit
power pattern (and the RF exposure compliance).
[0109] In certain aspects, the transmit power pattern may be
indicative of a rolling or moving average transmitted power over a
time interval, where the time interval may be separate from the
time window associated with the RF exposure limit. The average
transmit power may be used in selecting a cap on the transmit
power. For example, the UE may determine a potential instantaneous
transmit power using a specific algorithm associated with the RF
exposure limit, and the UE may cap that determined potential
instantaneous transmit power to a level that is a reciprocal of
past transmit power usage (e.g., the rolling average transmit power
over the past X seconds), where `X` may be less than the time
window associated with the RF exposure limit. Such a reciprocal may
be effective at adjusting the transmit power in scenarios of
transmission bursts (for example, as depicted in FIG. 5A) or a
continuous transmission (for example, as depicted in FIG. 5B). In
aspects, the cap on the transmit power based on the average
transmit power as described herein may account for changes in
network duty cycle over time, low or high transmit powers, and/or
user behavior. The cap on the transmit power as described herein
may be applied to frequency division duplex (FDD) and/or time
division duplex (TDD) schemes. The cap on the transmit power as
described herein may account for near, mid, and/or far cell power
levels and/or user behavior (e.g., burst usage vs. continuous
usage).
[0110] An example expression for determining the capped transmit
power in a single transmission scenario is as follows:
MTPL ' = min .times. { MTPL , Plimi .times. t prev . usa .times. g
.times. e } ( 9 ) ##EQU00010##
where MTPL' is the capped level for the transmit power for a single
transmission; MTPL is the potential instantaneous maximum transmit
power level determined for the RF exposure time window according to
a specific algorithm; prev.usage may be the minimum of (e.g., the
lowest value among) the normalized average transmit power over X
seconds (e.g., average transmit power over X seconds/P.sub.limit)
and unity (i.e., 1, for the normalization of
P.sub.limit/P.sub.limit); and P.sub.limit may be the maximum
average transmit power corresponding to the RF exposure limit
averaged over a time window T. Under Equation (9), if the average
transmit power for the recent history of X seconds is zero, for
example, in a bursty traffic scenario, MTPL' may equal MTPL and not
be capped because
Plimi .times. t prev . usa .times. g .times. e ##EQU00011##
will be extremely high. Thus, MTPL' may initially equal P.sub.max.
In a continuous transmission scenario, at the beginning of the
transmission, MTPL' may also equal MTPL and not be capped, due to
the lack of previous transmit history in the transmit power
pattern. As the UE continues to transmit, the cap
Plimi .times. t prev . usa .times. g .times. e ##EQU00012##
and hence, the instantaneous transmit power, will start to decrease
and settle to P.sub.limit due to the
Plimit prev . usage ##EQU00013##
term being less than or equal to the MTPL term, and near the end of
a time window, the transmit power may be less than P.sub.limit due
to the MTPL term being less than the
Plimit prev . usage ##EQU00014##
term.
[0111] Example expressions for determining the capped transmit
power in a dual transmission scenario are as follows:
pri . MTPL ' = min .times. { pri . MTPL , max .function. [ pri . a
, pri . b ] } , .times. .times. pri . a = pri . Plimit pri . prev .
usage + sec . prev . usage .times. pri . prev . usage pri . prev .
usage + sec . prev . usage , .times. pri . b = pri . Plimit num_Tx
( 10 .times. a ) sec . MTPL ' = min .times. { sec . MTPL , max
.function. [ sec . a , sec . b ] } , .times. .times. sec . a = sec
. Plimit pri . prev . usage + sec . prev . usage .times. sec . prev
. usage pri . prev . usage + sec . prev . usage , .times. sec . b =
sec . Plimit num_Tx ( 10 .times. b ) ##EQU00015##
where "pri" denotes the parameters for a primary transmit radio,
"sec" denotes the parameters for a secondary transmit radio, and
num_Tx represents the total number of active transmit radios, which
in this example, is two. The active transmit radios may refer to
the transmit antenna(s) and/or antenna module(s), which includes an
array of antennas, that will be simultaneously transmitting during
the second transmissions.
[0112] An example expression for determining the capped transmit
power in a multi-transmission scenario is as follows:
MTPL i ' = min .times. { MTPL i , max .function. [ a i , b i ] } ,
.times. a i = Plimit i n = 1 num .times. _ .times. Tx .times. prev
. usage n .times. prev . usage i n = 1 num .times. _ .times. Tx
.times. prev . usage n , .times. b i = Plimit i num_Tx ( 11 )
##EQU00016##
where i is the index for a particular radio among a plurality of
radios.
[0113] With respect to the operations 600, the transmit power
determination at block 604 may include determining a first transmit
power (e.g., MTPL) and determining a second transmit power
( e . g . , Plimit prev . usage ) ##EQU00017##
based at least in part on a normalized average transmitted power
(e.g., prev.usage) over a time interval (e.g., X seconds, which may
be less than the time window associated with the RF exposure
limit). The UE may select a third transmit power as a minimum of
the first transmit power and the second transmit power, for
example, as described herein with respect to Equation (9). The UE
may determine the transmit power for the one or more second
transmissions such that the transmit power is less than or equal to
the third transmit power. The second transmit power may be based at
least in part on a reciprocal of the normalized average transmitted
power
( e . g . , 1 prev . usage ) ##EQU00018##
in a past time interval. The second transmit power may be a
product
( e . g . , Plimit prev . usage ) ##EQU00019##
of a maximum average power (e.g., P.sub.limit) corresponding to the
RF exposure limit over a reciprocal of a minimum of the normalized
average transmitted power and unity.
[0114] In a multi-transmission scenario, the transmit power
determination at block 604 may include determining a first transmit
power for each of a plurality of radios and determining a second
transmit power for each of the plurality of radios, where the
second transmit power may be based at least in part on a normalized
average transmitted power for the respective radio over a time
interval. The UE may select a third transmit power for each of the
plurality of radios as a minimum of the first transmit power and
the second transmit power for the respective radio. The UE may
determine the transmit power for the one or more second
transmissions such that the transmit power for each of the
plurality of radios is less than or equal to the third transmit
power for the respective radio.
[0115] The determination of the second transmit power may include
determining a fourth transmit power
( e . g . , Plimit n = 1 num .times. _ .times. Tx .times. prev .
usage n .times. prev . usage i n = 1 num .times. _ .times. Tx
.times. prev . usage n ) ##EQU00020##
based at least in part on a product between a maximum average power
corresponding to the RF exposure limit for the respective radio and
a reciprocal of a sum of minimums of a normalized average
transmitted power for the plurality of radios and unity. The fourth
transmit power may be further based on a proportion between the
normalized average transmitted power for the respective radio and a
total of the normalized average transmitted powers for the
plurality of radios. The UE may determine a fifth transmit
power
( e . g . , Plimit i num_Tx ) ##EQU00021##
that is me maximum average power corresponding to the RF exposure
limit divided by a number of the plurality of radios. The UE may
select the second transmit power based on a maximum of (e.g., the
largest value among) the fourth transmit power and the fifth
transmit power (e.g., max[a.sub.i, b.sub.i]).
[0116] In certain aspects, the time interval for the average
transmit power used in selecting the transmit power cap may be
updated dynamically, for example, based on the time-averaged
exposure (or average transmit power) and/or network conditions. The
time interval may be determined based on the following
expression:
X=max{m,n.times.(1-average_exposure(t))} (12)
where m may be the lowest value for X in terms of seconds, n may be
the highest value for X in terms of seconds, and the
average_exposure(t) may be the total average normalized exposure
for all the transmitting radios (or sum of average transmit
power/P.sub.limit for all past transmissions from all radios) over
the past time window (T) associated with the RF exposure limit. In
certain cases, n may be less than the time window associated with
the RF exposure limit. Different X values may be suitable for short
burst transmissions versus long transmissions. Equation (12) may
enable a UE to adjust the time interval as the uplink and/or
sidelink traffic changes over time. Additionally, m and/or n can
also vary from one transmitting radio to another transmitting radio
depending on the time-averaged window associated with the radio.
For example, if two transmitting radios are averaged over two
different time-averaged windows (for example, a time window for a
sub-6 GHz radio and a separate time window for a mmWave radio), the
value for X, and in certain cases, the values for m and/or n may be
different between the two radios.
[0117] With respect to the operations 600, the transmit power
determination at block 604 may include adjusting the time interval
for the normalized average transmitted power based at least in part
on an average power over a time window (T) corresponding to the RF
exposure limit. In some aspects, the average power may be a rolling
or moving average of the transmitted power over the time window.
The time interval adjustment may include selecting a maximum among
a first time interval (m) and a second time interval (n) varying
with (e.g., proportional to) the average power over a past time
window, for example, as described herein with respect to Equation
(12). In certain cases, the first time interval and the second time
interval depend on a transmission frequency of the one or more
second transmissions. That is, the value for the first time
interval and/or the value for the second time interval may vary
depending on the transmission frequency. For example, the second
time interval may be higher for sub-6 GHz transmissions than a
corresponding second time interval for mmWave transmissions.
[0118] In certain aspects, the time interval may be adjusted based
on one or more network conditions. For example, in poor network
conditions (such as a UE being on a cell edge and/or being in a
mobility scenario), the time interval may be adjusted to a longer
duration, such as n in Equation (12), for example, due to the
greater redundancy and longer transmissions encountered with poor
network conditions. In desirable network conditions (such as the UE
being stationary and in close proximity with a base station), the
time interval may be adjusted to a short duration, such as m in
Equation (12), for example, due to the reduced redundancy and
shorter transmissions encountered with desirable network
conditions. With respect to the operations 600, the transmit power
determination at block 604 may include adjusting the time interval
for the normalized average transmitted power based at least in part
on one or more current network conditions, such as one or more of
the parameters further described herein with respect to the network
pattern.
[0119] In certain aspects, the cap on the maximum transmit power
described herein may enable an implementation without altering the
underlying algorithm or processing that determines MTPL, which
guarantees RF exposure compliance. In other words, as the original
algorithm or processing for MTPL is unaltered, the cap can be
applied on any algorithm or processing that generates MTPL. In some
aspects, the algorithm or processing that determines MTPL functions
separately or independently of an algorithm or processing that
determines the cap. For example, a first process may be executed to
determine transmit powers that comply with RF exposure limits, and
a second process may be independently executed to determine whether
to cap the determined transmit powers. In some aspects, the second
process runs on a different layer (e.g., an application layer or
other layer, for example, in the Open Systems Interconnection (OSI)
model) as compared to the first process.
[0120] The transmit power determination at block 604 may include
determining a first transmit power (e.g., MTPL) and applying a cap
to the first transmit power to determine a second transmit power
(e.g., MTPL'), for example, as described herein with respect to
Equation (9). The UE may determine the transmit power for the one
or more second transmissions such that the transmit power is less
than or equal to the second transmit power.
[0121] In certain aspects, the UE may determine the transmit power
at block 604 by selecting one of three options: (1) the
instantaneous transmit power (e.g., MTPL) determined according to a
specific algorithm for RF exposure compliance; (2) a minimum of the
instantaneous transmit power and the transmit power based on the
normalized average transmitted power for a radio over a time
interval
( e . g . , Plimit prev . usage ) , ##EQU00022##
where the minimum operations ensures compliance with the RF
exposure limit; and (3) a minimum of the instantaneous transmit
power and a maximum average power corresponding to the RF exposure
limit (e.g., P.sub.limit), where the minimum operations again
ensures compliance with the RF exposure limit.
[0122] With respect to the operations 600, the transmit power
determination at block 604 may further include determining a first
transmit power (e.g., MTPL) for the one or more second
transmissions based at least in part on a time-averaged RF exposure
in a past time window; determining a second transmit power
( e . g . , Plimit prev . usage ) ##EQU00023##
based at least in part on a normalized average transmitted power
for a radio over a time interval; and determining a third transmit
power (e.g., P.sub.limit) that is a maximum average power
corresponding to the RF exposure limit. The UE may select a fourth
transmit power as a minimum of the first transmit power and the
second transmit power for the radio and select a fifth transmit
power as a minimum of the first transmit power and the third
transmit power for the radio. The UE may select a sixth transmit
power among the first transmit power, the fourth transmit power,
and the fifth transmit power, for example, depending on the pattern
as described herein. The UE may determine the transmit power for
the one or more second transmissions such that the transmit power
is less than or equal to the sixth transmit power for the
radio.
[0123] In a multi-transmission scenario, the transmit power
determination at block 604 may further include determining a first
transmit power (e.g., MTPL.sub.i) for each of a plurality of
radios, where the first transmit power is based at least in part on
a time-averaged RF exposure in a past time window; determining a
second transmit power
( e . g . , Plimit i n = 1 num .times. _ .times. Tx .times. prev .
usage n .times. prev . usage i n = 1 num .times. _ .times. Tx
.times. prev . usage n ) ##EQU00024##
for each of the plurality of radios, where the second transmit
power is based at least in part on a normalized average transmitted
power for the respective radio over a time interval; and
determining a third transmit power
( e . g . , Plimit i num_Tx ) ##EQU00025##
for each of the plurality of radios, where the third transmit power
is a maximum average power (e.g., P.sub.limit) corresponding to the
RF exposure limit divided by a number of the plurality of radios.
The UE may select a fourth transmit power for each of the plurality
of radios as a minimum of the first transmit power and the second
transmit power for the respective radio and select a fifth transmit
power for each of the plurality of radios as a minimum of the first
transmit power and the third transmit power for the respective
radio. The UE may select a sixth transmit power for each of the
plurality of radios among the first transmit power, the fourth
transmit power, and the fifth transmit power for the respective
radio, for example, depending on the pattern as described herein.
The UE may determine the transmit power for the one or more second
transmissions such that the transmit power for each of the
plurality of radios is less than or equal to the sixth transmit
power for the respective radio.
[0124] The antenna usage pattern may indicate when the UE switches
to a different transmission antenna and the duration the UE uses a
particular antenna for transmission over time. For example, the UE
may identify when the UE has switched to a different transmission
antenna based on the antenna usage pattern, and the UE may perform
such a switch for the second transmissions in order to gain more RF
exposure margin (e.g., if the target antenna for the antenna change
is not in close proximity to human tissue) or determine that
another antenna with more RF exposure margin is likely to be
available for use at a later time and thus additional power can be
assigned to a current transmission with a relatively low risk of
exceeding the RF exposure limit in the future.
[0125] Certain aspects of the present disclosure may provide an
apparatus and/or technique for setting a transmit power ceiling for
a specific radio, for example, based on the antenna usage
associated with other radios, where the transmit power ceiling is
separate from the average power limit associated with an RF
exposure limit and the maximum transmit power supported by a radio.
That is, the antenna usage over time for one or more radios (e.g.,
sub-6 GHz radios) may be used to determine the transmit power for
another radio (e.g., a mmWave radio) in a multi-radio transmission
scenario. When ensuring RF exposure compliance, the overall
available RF exposure margin based on past usage of all radios may
be further split into separate margins for the radios based on a
priority and/or a desirable margin for the radios. As further
described herein, the margin for a specific radio may be adjusted
over time, for example, based on the usage of other radios. If a
radio desires consistent performance over time, the RF margin may
be capped based on the average past usage of other radios. For
example, suppose the past usage for a Frequency Range 1 (FR1)
(sub-6 GHz) radio indicates that the FR1 radio is using a relative
small portion of the total RF exposure margin. In such a case, the
UE may allocate a transmit power ceiling for a Frequency Range 2
(FR2) (mmWave) radio to provide consistent performance based on the
past usage for the FR1 radio. As an example, the UE may allocate a
transmit power ceiling that devotes a majority of the RF exposure
margin (e.g., 90%) to the FR2 radio.
[0126] In multi-transmission (e.g., when multiple radios are used
for concurrent transmissions) and/or multi-radio scenarios (e.g.,
when a wireless communication device is equipped with multiple
radios), the overall available RF exposure margin may be determined
according to the following expression:
A=100%-past time-averaged usage of (radio.sub.1+ . . .
+radio.sub.i) (13)
where A is the overall available RF exposure margin, and the past
time-averaged usage may be the sum of the time-averaged transmit
powers over a specific time interval for each of the radios, such
as a portion of the time window associated with an RF exposure
limit, the whole time window, or a time interval longer than the
time window (e.g., multiple time windows, one or more hours, or one
or more days).
[0127] The individual RF exposure margins allocated to each radio
may be determined according to the following expression:
Margin.sub.1=x.sub.1*A (for radio1),
Margin.sub.2=x.sub.2*A (for radio2), . . . ,
Margin.sub.i=x.sub.i*A (for radio.sub.i), (14)
where x.sub.1 through x.sub.i are factors used to allocate a
proportion of the overall available RF exposure margin to
respective radios, and x.sub.1+x.sub.2+ . . . +x.sub.i=1. In
certain aspects, the UE may adjust the values of x.sub.1 through
x.sub.i for one or more of the radios depending on one or more
criteria. For example, the value of x for a specific radio may be
determined based on a likelihood of that radio being used for
transmission, such as based on an application, a data buffer, a
traffic model or pattern associated with the radio. In certain
cases, the value of x for a specific radio may be determined based
on a priority, such as a priority for a certain channel and/or RAT
(e.g., LTE vs. 5G) over another, where a radio may be associated
with a specific channel. The channel priority may be based on a
transmission duty cycle associated with the channel. In the context
of an application or a service, suppose one radio is transmitting
content for a live video call and another radio is transmitting
data. In such a case, for example, the UE may provide priority to
the radio servicing the video call, which may result in a larger
portion of the RF margin (i.e., a larger value for x) being
assigned to that radio.
[0128] A transmit power ceiling for a specific radio (e.g.,
radio.sub.k) may be determined according to the following
expression:
cap_radio.sub.k=100%-past time-averaged usage of remaining radios
(radio.sub.1+radio.sub.2+ . . . +radio.sub.k-1+radio.sub.K+1)
(15)
[0129] The RF margin allocated to radio.sub.k may be determined
according to the following expression:
minimum(x.sub.k*A,cap_radio.sub.k) (16)
[0130] The operations 600 may further involve the UE determining a
transmit power ceiling for a specific radio as described herein. In
aspects, the antenna usage pattern may include a usage pattern for
each radio among a plurality of radios (such as the transceivers
254a-254r of FIG. 2). At block 604, the UE may determine an overall
available RF exposure margin based on a usage pattern for each
radio among a plurality of radios, for example, according to
Equation (13). In aspects, the UE may determine a difference of a
maximum available usage (e.g., 100%) and a sum of the usage
patterns for the radios (e.g., a sum of the average transmitted
powers). In certain cases, such as a single-transmission scenario
(e.g., when only a single radio is used for transmission) and/or
single-radio scenario (e.g., when a wireless communication device
is equipped with a single radio), the UE may determine the transmit
power ceiling for a radio based on a usage pattern for the radio,
and the UE may determine the transmit power for the one or more
second transmissions based at least in part on the transmit power
ceiling. In such cases, the transmit power ceiling may be less than
a maximum transmit power (P.sub.max) supported by the UE and
greater than an average power limit (P.sub.limit) associated with
the RF exposure limit
(P.sub.limit.ltoreq.P.sub.cap.ltoreq.P.sub.max).
[0131] The UE may allocate an RF exposure margin to each of the
radios based on the overall available RF exposure margin, for
example, according to Equation (14). In aspects, the UE may
allocate a proportion of the overall available RF exposure margin
to each of the radios as the RF exposure margin for the respective
radios. In certain cases, the UE may apply a priority to a specific
radio in allocating the RF exposure margin to a specific radio.
That is, the UE may allocate the proportion of the overall
available RF exposure margin to each of the radios based at least
in part on a priority associated with at least one of the radios.
The priority and/or the proportion may be associated with at least
one of a frequency band, an application, a service, a network
condition, or an exposure scenario (e.g., head exposure, body
exposure, extremity exposure, or hotspot exposure) associated with
the respective radio. That is, the UE may control the split in
available RF exposure margin among multiple radios in real-time by
varying the values for the factors x.sub.1 through x.sub.i. In
aspects, the UE may adjust the factors x.sub.1 through x.sub.i in
conjunction with radio priorities that can change over time with
applications, network conditions, and/or usage scenarios (for
example, hotspot mode). Expressed another way, the priorities and
the proportions may be adjusted over time in response to changes to
an application, service, network conditions, etc. For example, the
UE may allocate a greater proportion of the overall available RF
exposure margin to a particular radio based on that radio's
operating frequency band, such as a mmWave radio. As an example,
suppose the UE has a total of four radios. In this example, the UE
may adjust the factor x.sub.k for the mmWave radio to be 0.5 and
allocate the remaining RF exposure margin evenly among the
remaining radios (e.g., 0.16).
[0132] The UE may determine a transmit power ceiling (e.g.,
cap_radio.sub.k) for one of the radios based on the usage pattern
for each of the other radios, for example, according to Equation
(15). In aspects, the UE may determine the transmit power ceiling
to be a difference between the maximum available usage (e.g., 100%)
and a sum of the usage patterns for each of the other radios (e.g.,
the sum of the average transmitted powers for the other
radios).
[0133] The UE may determine the transmit power for the second
transmissions based at least in part on the transmit power ceiling
and the RF exposure margin allocated to the one of the radios. For
example, the UE may determine the transmit power as being less than
or equal to the RF margin allocated in Equation (16). In certain
cases, the UE may adjust the transmit power ceiling in response to
a change in the usage pattern for the radios (in a multi-radio
scenario) and/or the radio (in a single-radio scenario). As an
example, suppose the usage pattern for a sub-6 GHz radio indicates
that more transmit power can be allocated to a mmWave radio, for
example, due to a reduction in usage by the sub-6 GHz radio. In
response to the updated usage pattern, the UE may increase the
transmit power ceiling assigned to the mmWave radio based on the
usage patterns for the other radios.
[0134] In certain aspects, the UE may adjust the transmit power
ceiling in response to a change in a transmission scenario
associated with the radios. For example, the transmission scenario
may be associated with certain radios being used concurrently, an
exposure scenario (head exposure, body exposure, extremity
exposure, etc.), and/or a region in which the UE is located.
[0135] In certain aspects, the UE may adjust the transmit power
ceiling based at least in part on a traffic model. The UE may
develop a traffic model associated with the radios, where the
traffic model indicates when to adjust the transmit power ceiling.
As an example, the traffic model may provide that during a certain
time of day, a higher transmit power ceiling may be allocated to a
particular radio.
[0136] In aspects, the usage pattern for each radio among the
plurality of radios may include an average transmitted power in a
past time interval associated with the respective radio. For
example, the UE may determine the average transmitted power for
each of the radios over the past time window associated with an RF
exposure limit.
[0137] At block 606, the UE may transmit the second transmissions
at the transmit power ceiling for a first portion of a time window
associated with the RF exposure limit and may transmit the second
transmissions at another transmit power less than the transmit
power ceiling for a second portion of the time window, for example,
as described herein with respect to FIG. 9B.
[0138] The user behavior pattern may indicate when a user uses or
does not use the UE for wireless communications. The user behavior
pattern may include one or more times associated with when and/or
how the user uses or does not use the UE for wireless
communications. For example, if the user is likely to generate
transmission data in periodic/non-periodic bursts or in a
continuous manner (e.g., over long durations), the user behavior
pattern may indicate when the user typically refrains from using
the UE, such as during sleep, exercise, or other activities. During
such periods, the UE may allow the transmit power to exceed the
average power level (e.g., P.sub.limit) in the time window for RF
exposure compliance based on the assumption that additional
transmissions probably will not be initiated by the user. That is,
during such periods of likely low or no usage indicated by the user
behavior pattern, the UE may determine that continuous transmission
is unlikely (e.g., due to a user not being likely to initiate such
transmission) and thus allow transmissions at instantaneous powers
above P.sub.limit (e.g., at P.sub.max). In contrast, during periods
when the user typically uses the UE (e.g., when the user wakes up
in the morning, during lunch, or in the evening), the UE may
restrict transmissions at instantaneous powers above P.sub.limit,
for example, based on the assumption that additional transmission
probably will be initiated by the user and thus much of the
transmission window will likely be occupied with transmissions at
or near P.sub.limit. That is, the UE may set the transmit power to
be less than or equal to the maximum average transmit power level
P.sub.limit during periods when uplink activity is more likely as
indicated by the user behavior pattern. With respect to the
operations 600, the transmit power determined at block 604 may be
adjusted for the second transmissions based on the user behavior
pattern.
[0139] The application pattern may indicate various characteristics
associated with an application (e.g., a mobile software
application) that generates data for transmission. In aspects, the
application pattern may include a behavior of the application,
which may indicate at least one of one or more transmit times or
one or more transmit powers over time associated with the
application. For example, if the application pattern indicates that
the application generates data for transmission in periodic bursts,
the UE may correlate the periodic bursts to the time window
associated with the RF exposure limit and determine the transmit
power available for the application's transmissions based on the
duration of the periodic bursts. In certain cases, the pattern may
indicate the application type associated with the application
pattern. That is, the application type may indicate a kind of
application that generates data for transmission. For example, the
application type may be an indication that the application is a
social media application, a messaging application, an email
application, a video call application, a video conference
application, a video game, a video streaming application, a
navigation application, etc. In certain aspects, the UE may
prioritize the transmit power for one or more applications based on
the application type. The UE may identify the application type of
the second transmissions, for example, based on the application
type pattern and/or an explicit indication from an application
processor (e.g., the controller 280) employed by the UE, and the UE
may determine the transmit power for the second transmissions based
on the application type having priority over other application
types. For example, the UE may allocate more transmit power to
applications that stream audio and/or video, such as a video call
application or video conference application, versus other
applications. In some scenarios, the UE may refrain from allowing
lower priority applications to transmit at instantaneous power
levels above the maximum average power level (e.g., P.sub.limit)
when the UE has determined that it is likely that another
application of higher priority will transmit data within the same
exposure time window.
[0140] The wireless network pattern may indicate various aspects of
the wireless network conditions. The wireless network pattern may
include at least one of a channel quality between the UE and a
receiving entity (e.g., one or more base stations or other UEs), a
modulation and coding scheme (MCS) associated with the one or more
first transmissions, a coding rate (e.g., the proportion of the
data-stream that is non-redundant) associated with the one or more
first transmissions, a periodicity associated with the one or more
first transmissions, a duty cycle associated with the one or more
first transmissions, or a mobility scenario, such as an indication
of the UE's mobility during the one or more first transmissions. In
certain cases, the wireless network pattern may indicate the past
radio conditions (such as channel quality, MCS, coding rate, etc.)
encountered by the UE over time. The UE may use the past radio
conditions to anticipate future radio conditions and allocate the
transmit power for such radio conditions accordingly. For example,
suppose the UE identifies that the UE is engaged in a mobility
scenario (such as a commute to or from work) at certain periods of
time during the day. In such a case, UE may allocate a certain
transmit power to accommodate the mobility scenario. For instance,
the UE may allow for a transmit power at or above the maximum
average transmit power limit (P.sub.limit) when the UE identifies a
cell edge (e.g., poor radio conditions) based on the mobility
scenario indicated by the wireless network pattern. In contrast,
when the UE identifies that the UE is effectively immobile,
depending on the first transmissions, the UE may allocate a
transmit power that is less than or equal to the maximum average
transmit power limit (P.sub.limit) for the second transmissions due
to the assumption that the radio conditions will not adversely
change (such as during a mobility scenario).
[0141] Other parameters associated with the wireless network
conditions may also be included in the wireless network pattern,
such as cell identifiers, the number of aggregated component
carriers, the number of MIMO layers, the bandwidth, the subcarrier
spacing, the frequency range (e.g., FR1 or FR2 under 5G NR), etc.
In aspects, the channel quality may include a path loss, a channel
quality indicator, signal-to-noise ratio (SNR),
signal-to-interference-plus-noise ratio (SINR),
signal-to-noise-plus-distortion ratio (SNDR), a reference signal
received power (RSRP), and/or a received signal strength indicator
(RSSI).
[0142] The transmission type or priority pattern may indicate what
type of transmissions have been sent and/or what their relative
priorities are. For example, this pattern may include information
about whether a voice call or data has been transmitted and the
pattern thereof. Such a pattern may be able to distinguish whether
voice and data are being transmitted concurrently and/or whether a
certain type of communication (e.g., voice) is likely to be
initiated while transmitting another type of communication (e.g.,
data). The pattern may include the relative priorities of the
transmission, such as voice having a higher priority than data or
certain types of data (e.g., Voice over Internet Protocol (VoIP),
videoconferencing, certain types of streaming) having a higher
priority than other types of data (e.g., email or file upload). In
some such aspects, a UE will not assign or will be less likely to
assign an instantaneous transmit power above the maximum average
power level (P.sub.limit) when the pattern indicates that another
transmission of higher priority is likely to be desired or when the
type of information that is likely to be transmitted often involves
a long transmission time (e.g., greater than an exposure time
window) and/or a relatively consistent amount of power over time.
In some aspects, one or more of the above patterns (e.g., the
antenna usage pattern, the application pattern, and/or the
transmission type pattern) may be used to determine whether to
utilize a 4G service or a 5G service, and/or whether to transmit in
a sub-6 GHz band or a mmWave band.
[0143] The sensor information may include various sensor data or
information generated by the UE. The sensor information may include
RF exposure sensor information over time such as the UE's distance
to various human body parts (e.g., hand, head, or body) over time
or when the UE is placed away from human tissue (e.g., in a hotspot
scenario or being charged). The UE may use the RF exposure sensor
information to adjust the maximum average transmit power level
(e.g., P.sub.limit) associated with the RF exposure limit. For
example, in cases where the sensor information indicates that the
UE will be in close proximity to human tissue (e.g., when the UE is
typically placed in the pocket of a user), the UE may adjust (e.g.,
reduce) the maximum average transmit power level (P.sub.limit) to
be in compliance with this RF exposure scenario. In contrast, if
the sensor information indicates that the UE will not be in close
proximity to human tissue, the UE may adjust (e.g., increase) the
maximum average transmit power level (P.sub.limit) to be in
compliance with this other RF exposure scenario. The sensor
information may include at least one of an indication of the UE's
proximity to a non-human object, an indication that the UE is in
free space, an indication of a user usage scenario, an indication
of a usage state of the UE, or an indication of when antenna
switching occurs at the UE. In aspects, the user usage scenario may
indicate to which portion of a user's body (e.g., hand, head, or
body) the UE is in proximity. The usage state may indicate whether
the UE is being used in proximity to human tissue, such as the UE
being used as a hotspot without being in proximity to human
tissue.
[0144] In certain aspects, the UE may use various models to
determine the transmit power based on the pattern at block 606. The
UE may use machine learning to predict/learn future transmissions
events based on the pattern. For example, the UE may use machine
learning to predict/learn future network/radio conditions (e.g., a
home-to-work route) and/or user behavior based on past network
conditions and/or user behavior, for example, represented by the
wireless network pattern and/or the user behavior pattern. That is,
the UE may use machine learning to map upcoming user behavior
(e.g., data bursts or a big data package) to current network
condition (e.g., stationary), or current user behavior to upcoming
network conditions (e.g., in mobility scenario), or both upcoming
user behavior and upcoming network conditions. In certain aspects,
the UE may use machine learning to predict other characteristics
associated with upcoming transmissions (such as antenna switching,
sensor information, application type and/or behavior, etc.) from
the pattern. In aspects, the characteristics predicted with the
pattern may be generated with various models or estimates, such as
machine learning, artificial intelligence, neural networks,
regression analysis, etc.
[0145] At block 606 for certain aspects, the UE may determine the
transmit power with machine learning based at least in part on the
pattern. In certain cases, the UE may generate upcoming user
behavior with machine learning based on the pattern (e.g., a user
behavior pattern) and determine the transmit power based on the
upcoming user behavior and current network conditions. In certain
aspects, the UE may generate upcoming network conditions with
machine learning based on the pattern (e.g., a wireless network
pattern) and determine the transmit power based on current user
behavior and the upcoming network conditions. In certain cases, the
UE may generate upcoming network conditions and upcoming user
behavior with machine learning based on the pattern (e.g., a
wireless network pattern and user behavior pattern) and determine
the transmit power based on the upcoming network conditions and the
upcoming user behavior.
[0146] In aspects, the UE may correlate the pattern to a transmit
time associated with the one or more second transmissions and
compare the transmit time to a time window associated with the RF
exposure limit. The UE may determine the transmit power based on
the comparison. For example, suppose the pattern correlates to a
short transmit time for an upcoming transmission that is less than
a time window associated with an RF exposure limit, the UE may
allocate a transmit power that is greater than the maximum average
transmit power level (P.sub.limit) and/or less than the maximum
supported transmit power (P.sub.max) for such a transmission.
[0147] In aspects, the RF exposure limit may be in compliance with
the limits set according to a regulatory/standards body (e.g., the
Federal Communications Commission (FCC) for the United States;
Innovation, Science and Economic Development Canada (ISED) for
Canada; or the International Commission on Non-Ionizing Radiation
Protection (ICNIRP) standard followed by the European Union (EU)).
The RF exposure limit may include a SAR limit and/or a PD limit for
various frequency ranges. In aspects, the UE may determine the
transmit power at block 604 to be in compliance with the RF
exposure limit. For example, when communicating via multiple
wireless technologies, the UE may compare a combined normalized
distribution, as described herein with respect to FIG. 4, with the
RF exposure compliance threshold for the multiple technologies. The
RF exposure limit may be averaged over time for a specified time
window, such as 4 seconds for transmit frequencies between 24 GHz
and 42 GHz, 100 seconds for transmit frequencies less than 3 GHz,
or 360 seconds for transmit frequencies less than 6 GHz.
[0148] FIG. 7A is a graph 700A illustrating an example pattern 702
being used to determine one or more transmit powers over time, in
accordance with certain aspects of the present disclosure. In this
example, the pattern 702 has two periodic first transmissions 704,
where each of the first transmissions has a duration 706, which is
less than a time window (T) associated with an RF exposure limit.
The UE may determine from the pattern 702 that second transmissions
708, 710 are likely to be transmitted in the upcoming time windows.
Based on the pattern 702, the UE may determine a transmit power for
the second transmissions 708, 710. For example, the UE may identify
that the first transmissions 704 have a transmit time (i.e., the
duration 706) that is less than the time window (T). As such, the
UE may allocate a transmit power to the second transmission 708
that is greater than P.sub.limit (such as P.sub.max), for example,
based on the pattern also indicating that the UE is likely to
experience a mobility scenario. The UE may allocate the transmit
power to the second transmission 710 at a transmit power closer to
P.sub.limit, for example, based on the pattern also indicating that
the UE is likely to be immobile. The UE may determine whether to
allocate a transmit power less than, equal to, or greater than the
maximum average transmit power level (P.sub.limit) based on the
pattern, such as past network conditions, user behavior,
application type, etc. In aspects, the pattern 702 may be (or
derived from) one or more various patterns, such as a transmit
power pattern, a user behavior pattern, an application pattern, a
wireless network pattern, and/or a sensor information pattern.
Although two time windows are used to determine a pattern in the
graph 700A, it is to be understood that more or less than two time
windows (or other time durations not based on exposure time
windows) may be used for the basis of a pattern.
[0149] FIG. 7B is a graph 700B illustrating another example pattern
722 being used to determine one or more transmit powers over time,
in accordance with certain aspects of the present disclosure. In
this example, the pattern 722 has one periodic transmission 724
that has a duration 726 greater than the time window (T) for RF
exposure. The UE may determine from the pattern 722 that additional
transmissions which will consume a majority of the power available
in an upcoming time window are likely to be transmitted in the
upcoming time window. Based on the pattern 722, the UE may
determine a transmit power for second transmissions 728. For
example, the UE may identify that the first transmission 724 has a
transmit time (i.e., the duration 726) that is greater than the
time window (T). As such, the UE may allocate a transmit power to
the second transmission 728 that is equal to or less than the
maximum average transmit power level (P.sub.limit). In certain
cases, the UE may identify that upcoming transmissions are likely
to overlap only a portion of one or more time windows (T), such
that additional transmit power 730 may be allocated to the second
transmission in one of the time windows (T).
[0150] FIG. 8A is a graph 800A illustrating an example pattern 802
being used to determine one or more transmit powers over time for
short transmissions (e.g., transmissions having a duration less
than the RF exposure time window, also referred to as "bursty
transmissions"), in accordance with certain aspects of the present
disclosure. In this example, the pattern 802 may be indicative of
an average transmit power over a time interval 804. In certain
cases, the pattern 802 may include a rolling or moving average of
the transmit power. The UE may select a new cap for the transmit
power based on the pattern 802, for example, using Equation (9).
Due to the average transmit power within the pattern 802 being less
than P.sub.limit, the UE may revert to using the MTPL as the
maximum transmit power (e.g., P.sub.max) available for
transmission. The UE may allocate a transmit power for the
transmission 806 that is equal to or less than the MTPL, which may
equal P.sub.max.
[0151] FIG. 8B is a graph 800B illustrating other example patterns
822a-c being used to determine one or more transmit powers over
time for a long transmission (e.g., a transmission having a
duration greater than the RF exposure time window), in accordance
with certain aspects of the present disclosure. In this example,
the transmission 808 may span across multiple time windows (T)
associated with the RF exposure limit. At the beginning of the
transmission 808, the average transmit power is zero within the
time interval 804 of the first pattern 822a, such that the UE may
select P.sub.max as the maximum transmit power, for example, under
Equation (9). Due to the reciprocal cap, the transmit power may
decay at a rate of the reciprocal function for the average transmit
power, and the transmit power may settle to P.sub.limit as the
average transmit power over the time interval approaches
P.sub.limit. At a subsequent transmission occasion (e.g., during
the same time window T), the average transmit power may be equal to
P.sub.limit within the time interval 804 of the second pattern
822b. In such a case, the UE may effectively select P.sub.limit as
the minimum of MTPL and
Plimit prev . usage , ##EQU00026##
for example, due to the MTPL being greater than
Plimit prev . usage . ##EQU00027##
At a later transmission occasion (e.g., during the same time window
T), the average transmit power may still be equal to P.sub.limit
within the time interval 804 of the third pattern 822c. However,
MTPL may be less than P.sub.limit in order to ensure compliance
with the RF exposure limit, such that the UE selects MTPL for the
remainder of the time window (T) as the maximum transmit power
available for the transmission 808.
[0152] In certain aspects, the transmit power selected by the UE at
the beginning of a subsequent time window (T) is less than the
transmit power selected at the beginning of the transmission 808.
While the average transmitted power of the first pattern 822a is
zero in the example illustrated in FIG. 8B, the average power
transmitted between the end of the interval 804 corresponding to
the pattern 822c and the beginning of the subsequent time window
(T) is illustrated as being non-zero (e.g., between zero and
P.sub.limit). The transmit power selected by the UE (e.g.,
according to Equation (9)) at the beginning of this subsequent time
window (T) may therefore be less than P.sub.max (but greater than
P.sub.limit). Further, the average transmit power selected at the
end of this subsequent time window (T) may be even closer to
P.sub.limit than the average transmit power selected at the end of
the first time window. This may cause the transmit power selected
by the UE at the beginning of an even later transmit window (T)
(e.g., represented by the peak furthest to the right in FIG. 8B) to
be closer to P.sub.limit as well. It can therefore be observed that
in certain aspects, the transmission power selected by the UE will
approach P.sub.limit for continuous/long (e.g., having a duration
greater than a time window) transmissions.
[0153] While certain aspects of the present disclosure are
described herein with respect to using a pattern, representing
historical behaviors or conditions, to determine a transmit power
in compliance with an RF exposure limit to facilitate
understanding, a UE may also apply aspects of the present
disclosure using current conditions (such as current radio
conditions and/or a data buffer) to validate, adjust, or compensate
the transmit power determination based on the pattern. For example,
the UE may determine a likely or expected usage or transmit power
in a current or future time window based on a pattern of past
information, and may thereafter compare the likely or expected
usage or transmit power to data stored in a transmit buffer. In
some such aspects, the UE may determine a first power for a current
or future transmission, and if the data in the transmit buffer
differs from the expected usage by greater than a first threshold
or would involve an amount of power to transmit which differs from
the expected transmit power by more than a second threshold, the
first power may be adjusted prior to being used to set an
instantaneous transmit power.
[0154] It should be appreciated that determining the transmit power
based on a pattern (e.g., a transmit power pattern, user behavior
pattern, etc.) provides various advantages. In certain cases, the
transmit power determination may enable the UE to allocate a
transmit power that adapts to historical conditions and/or patterns
in compliance with an RF exposure limit. With such an adaptive
transmit power scheme, the UE may be able to provide desirable
transmit powers for specific user behavior, network conditions,
application types, etc.
[0155] FIG. 9A is a graph 900A illustrating an example antenna
usage pattern 902 of a first radio, in accordance with certain
aspects of the present disclosure. In this example, the antenna
usage pattern 902 for the first radio shows that first
transmissions 904 may be transmitted in bursts less than the time
window T.sub.0 associated with an RF exposure limit. In such a
case, this may leave additional RF exposure margin for another
radio, such as a second radio.
[0156] FIG. 9B is a graph 900B illustrating an example of setting a
transmit power ceiling (P.sub.cap) to the second radio based on the
antenna usage pattern illustrated in FIG. 9A, in accordance with
certain aspects of the present disclosure. In this example, the UE
may determine the transmit power ceiling (P.sub.cap) for the second
radio according to Equation (15) and/or Equation (16). In certain
cases, after a certain offset (t) in time from the instance of the
time window T.sub.0 in FIG. 9A, the UE may transmit a second
transmission 906 at the transmit power ceiling for a first portion
908 of the time window T.sub.1 and transmit the second transmission
906 at another transmit power less than the transmit power ceiling
for a second portion 910 of the time window T.sub.1 to maintain the
averaged transmit power within the P.sub.limit associated with the
RF exposure limit. As the time window T.sub.0 may represent the
time for a past usage pattern, T.sub.1 may be spaced in time from
T.sub.0 by a certain offset (t) in time. In certain aspects, the
transmit power ceiling may facilitate a consistent level of
performance for the second radio during the time window associated
with the RF exposure limit.
[0157] The transmit power ceiling may apply to a single radio
transmission scenario (e.g., where a single radio is transmitting)
or a multi-radio transmission scenario (e.g., where multiple radios
are transmitting concurrently). Capping P.sub.max may extend the
portion of the time window where the wireless communication device
is transmitting above P.sub.limit. For single radio, where
P.sub.cap is set less than P.sub.max, the transmit power can
transmit at the P.sub.cap level for a longer time before
encountering an exposure limit when compared to transmitting at the
P.sub.max level. Similarly for a multi-radio scenario, the portion
of RF exposure margin (x.sub.k*A) may be capped for radio.sub.k,
and P.sub.cap for radio.sub.k can be determined according to
(x.sub.k*A*P.sub.limit_radio_k), where P.sub.limit is the average
transmit power associated with the RF exposure limit.
Example Transmit Energy Depending on Transmit Time while
Maintaining RF Exposure Compliance
[0158] In certain aspects, the UE may consider future conditions
(such as transmit time and/or radio conditions) in determining the
transmit power for RF exposure compliance. Aspects of the present
disclosure provide techniques and apparatus for determining
transmit power and/or switching between the various transmission
modes described herein based on a transmit time associated with
data and/or radio conditions while ensuring RF exposure compliance.
In certain aspects, the transmit time may be derived from a size
(e.g., a data buffer size) associated with the data and a current
(or predicted future) data rate. As an example, if the data buffer
size is large (e.g., the transmit time is greater than the time
window associated with the RF exposure limit), then the transmitter
may operate under the peak mode (e.g., described herein with
respect to FIG. 5B) to enable continuous transmission at the
average power level (e.g., P.sub.limit). If the data buffer size is
small (e.g., the transmit time is less than the time window
associated with the RF exposure limit), then the transmitter may
operate under the time-average mode (e.g., described herein with
respect to FIG. 5C) and transmit at the maximum power followed by
reserve power if needed to complete the transmission.
[0159] The various techniques described herein for ensuring RF
exposure compliance may enable desirable transmit powers for data
transmissions and/or desirable power consumption. The desirable
transmit power may provide desirable uplink/sidelink performance,
such as desirable data rates, carrier aggregation, and/or a
connection at the edge of a cell.
[0160] FIG. 10A is a flow diagram illustrating example operations
1000A for wireless communication, in accordance with certain
aspects of the present disclosure. The operations 1000A may be
performed, for example, by a UE (e.g., the UE 120a in the wireless
communication network 100). The operations 1000A may be implemented
as software components that are executed and run on one or more
processors (e.g., controller/processor 280 of FIG. 2). Further, the
transmission of signals by the UE in the operations 1000 may be
enabled, for example, by one or more antennas (e.g., antennas 252
of FIG. 2). In certain aspects, the transmission and/or reception
of signals by the UE may be implemented via a bus interface of one
or more processors (e.g., controller/processor 280) obtaining
and/or outputting signals.
[0161] The operations 1000A may begin, at block 1002, where the UE
may obtain data for a transmission to a receiving entity (e.g., the
BS 110a or another UE) and radio conditions associated with the
transmission. At block 1004, the UE may determine a transmit time
associated with the data based at least in part on the radio
conditions. At block 1006, the UE may transmit, to the receiving
entity, a signal indicative of the data at a transmit power based
at least in part on the determined transmit time and an RF exposure
limit. In some aspects, the block 1004 may instead or in addition
include selecting a mode from a plurality of transmission modes
based on the radio conditions (or one or more other conditions)
and/or the data, and the block 1006 may instead include
transmitting, to the receiving entity, the signal indicative of the
data at a transmit power based at least in part on the selected
transmission mode and the RF exposure limit. In certain aspects,
the transmission mode may be selected based on an application or
service, such as a video call, voice call, live video stream,
online game, etc. For example, in a video call, the transmission
mode may be selected to transmit consistently (such as peak mode or
similar to peak mode as described herein with respect to FIGS.
11A-11C) irrespective of the radio conditions or other
conditions.
[0162] In certain aspects, the UE may determine the amount of
transmit time that will be used to transmit the data to the
receiving entity in order to select the transmission mode (e.g.,
time-average mode or peak mode). The determination of the transmit
time may be derived using various factors such as a given transmit
power, a data size or buffer size, and a data rate, which may be
derived using current radio conditions. The data rate may depend on
various factors or conditions, such as the channel quality between
the UE and receiving entity, the path loss between the UE and
receiving entity, the periodicity and/or duty cycle associated with
transmissions to the receiving entity, the modulation and coding
scheme (MCS), the coding rate (e.g., the proportion of the
data-stream that is non-redundant), the number of aggregated
component carriers, the number of MIMO layers, the bandwidth, the
subcarrier spacing, the frequency range (e.g., FR1 or FR2 under 5G
NR), etc. For example, a high MCS (e.g., 256QAM), high transmit
power (e.g., P.sub.max), high duty cycle, low path loss, and small
data size may result in a relatively short transmit time (e.g., a
transmit time less than the time window associated with the RF
exposure limit). In aspects, the radio conditions may be obtained
at block 1002 with a processor and/or modem, such as the controller
280 and/or modem (modulator/demodulator) in the transceivers
254.
[0163] With respect to the operations 1000A, the radio conditions
may include at least one of a channel quality between the UE and
the receiving entity, an MCS associated with the transmission, a
coding rate associated with the transmission, a number of
aggregated component carriers associated with the transmission, a
number of MIMO layers associated with the transmission, a
bandwidth, a subcarrier spacing, a frequency range associated with
the transmission, or a periodicity associated with transmissions to
the receiving entity. In aspects, the channel quality may include a
path loss, a channel quality indicator, signal-to-noise ratio
(SNR), signal-to-interference-plus-noise ratio (SINR),
signal-to-noise-plus-distortion ratio (SNDR), a reference signal
received power (RSRP), and/or a received signal strength indicator
(RSSI). In some aspects, the radio conditions may correspond to or
be determined based on the wireless network pattern described
herein with respect to FIGS. 6-9B.
[0164] The radio conditions may be used to derive a data rate or
throughput for transmitting the data to the receiving entity. The
data rate may be determined in terms of megabits per second (Mbps).
For example, the UE may determine a data rate associated with
transmitting the data to the receiving entity based on the radio
conditions, and the UE may determine the transmit time based on the
data rate and a size associated with the data. In certain aspects,
the UE may determine the data rate using the formula for the
approximate maximum uplink data rate as specified in the 3GPP
standards (such as Technical Specification 38.306, Section
4.1.2).
[0165] In certain aspects, the size associated with the data may be
in terms of bytes, bits, or other units of computer/digital
information. The size associated with the data may correspond to a
data buffer size used to temporarily store the data for
transmission. For example, the UE may determine the transmit time
based at least in part on a buffer size associated with the data.
In aspects, the UE may determine the transmit time based on a
buffer size associated with the data (which may be referred to as
an "upload data buffer size") and a data rate determined from the
radio conditions. In certain aspects, instead of obtaining the data
at block 1002, the UE may obtain the size associated with the data,
and the UE may determine the transmit time associated with the data
based on the data rate and data size.
[0166] In certain aspects, the transmit times may be determined for
various transmit powers, such as an instantaneous power limit
(e.g., P.sub.max in FIG. 5C) and an average power (e.g.,
P.sub.limit in FIG. 5B). As used herein the instantaneous power
limit may refer to the maximum transmit power supported by the UE
(such as P.sub.max) or other transmit power above the average
power. The average power may refer to the peak transmit power that
can be maintained for the duration of a time window associated with
an RF exposure limit in compliance with the RF exposure limit (such
as P.sub.limit). That is, the average power may be the average
power level corresponding to the RF exposure limit (e.g., aligned
with a regulatory requirement and/or a device manufacturer setting,
which is based on the regulatory requirement, but may be lower than
the regulatory requirement).
[0167] As an example, the transmit time may be selected from a
plurality of transmit times associated with a plurality of transmit
powers, where the plurality of transmit powers may include the
transmit power at which the signal is transmitted at block 1006.
The plurality of transmit times may include a first transmit time
associated with an instantaneous power limit supported by the UE
(e.g., the maximum transmit power supported by the UE) and a second
transmit time associated with an average power corresponding to the
RF exposure limit. In aspects, the first transmit time may be the
duration that the UE takes to transmit the data at the
instantaneous power limit (e.g., P.sub.max) regardless of any power
reserve margin and RF exposure compliance, and the second transmit
time may be the duration that the UE takes to transmit the data at
the average power (P.sub.limit).
[0168] With the determined transmit times, the UE may select a
transmission mode (such as the time-average mode or peak mode) to
ensure RF exposure compliance with the RF exposure limit. As an
example, the time-average mode may be suited for short transmit
times or burst traffic to enable the UE to transmit at its maximum
power (e.g., P.sub.max), while still maintaining RF exposure
compliance and reserving a transmit power margin within the time
window associated with the RF exposure limit. The peak mode may be
suited for transmissions with a relatively long transmit duration
(e.g., transmissions with a duration greater than the time window).
In certain cases, the transmitter may intelligently toggle between
the time-average mode and peak mode based on the transmit times
determined from the radio conditions (and in some cases, from the
upload data buffer size). In some aspects, a transmit time is not
explicitly calculated or determined, but a transmission mode is
determined or otherwise selected based on one or more of the
(radio) conditions described above and the data for transmission
using the concepts discussed herein.
[0169] In aspects, the UE may select the transmission mode used to
transmit the signal at block 1006 based on various
thresholds/conditions associated with the transmit time (or
otherwise based on the conditions) determined at block 1004. For
example, if the transmit time at P.sub.max determined at block 1004
is less than or equal to the burst transmit time, the UE may
operate in time-average mode to transmit the signal at block 1006,
where the burst transmit time may refer to the maximum duration the
UE can transmit at P.sub.max and have enough reserve power to
continue transmitting at a reduced transmit power within the time
window associated with the RF exposure limit. The reduced transmit
power may be at a sufficient level to maintain a connection with
the receiving entity. The burst transmit time may be the duration
associated with P.sub.max as depicted in FIG. 5C (or the combined
durations of multiple bursts). Here, the transmit time at P.sub.max
and the burst transmit time may be scaled based on an estimated
(uplink) transmission duty cycle (as described herein) for
comparison between the transmit time at P.sub.max and the burst
transmit time and/or for comparing against the time window. For
example, if the transmission duty cycle is sufficiently low, the
burst transmit time scaled by (1/duty_cycle) may be greater than
the time window, in which case, the UE may transmit at P.sub.max
continuously in the time-average mode for such a low transmission
duty_cycle without time-averaged exposure exceeding P.sub.limit.
Similarly, if P.sub.limit.gtoreq.P.sub.max, the burst transmit time
will be greater than the time window (e.g., 4, 100 or 360 seconds),
in which case, UE operation in either time-average mode or peak
mode will allow the UE to transmit at P.sub.max continuously and
time-averaged transmit power will not exceed P.sub.limit.
[0170] The UE may determine the peak transmit for a given
P.sub.max, P.sub.limit, and/or P.sub.reserve. If the transmit time
at P.sub.limit as determined at block 1004 is greater than the time
window (e.g., 4, 100, or 360 seconds) associated with the RF
exposure limit, the UE may operate in peak mode to transmit the
signal at block 1006. If any of the transmit times determined at
block 1004 is greater than the burst transmit time and less than
the time window associated with the RF exposure limit, the UE may
operate in time-average mode to transmit the signal at block 1006.
In such a case, the UE may transmit the signal at a power level
between P.sub.max and P.sub.limit to provide a longer high power
duration at this power level or transmit at P.sub.max and lower
P.sub.reserve to increase the high power duration at the P.sub.max
level. In other words, the transmit power at block 1006 may be
adjusted (e.g., increased or decreased) while the signal is being
transmitted to ensure compliance with the RF exposure limit.
[0171] With respect to the operations 1000A, the transmit power at
block 1006 may be limited by the instantaneous power limit (e.g.,
P.sub.max) if the first transmit time determined at block 1004 is
less than or equal to a burst transmit time associated with the
instantaneous power limit in compliance with the RF exposure limit,
where the burst transmit time is less than a time window associated
with the RF exposure limit. In aspects, the transmit power may be
limited by the average power if the second transmit time determined
at block 1004 is greater than or equal to the time window
associated with the RF exposure limit. If the transmit time
associated with any of the plurality of transmit powers determined
at block 1004 is less than or equal to the time window, and is
greater than or equal to the burst transmit time, the transmit
power at block 1006 may be less than or equal to the instantaneous
power limit and greater than the average power for a first portion
of the transmit time, and the transmit power at block 1006 may be
less than the average power for a second portion of the transmit
time.
[0172] As an example, with respect to the operations 1000A, the
transmit power at block 1006 may be set according to a time-average
mode (such as the time-average mode described herein with respect
to FIG. 5C) if the transmit time determined at block 1004 is less
than or equal to the burst transmit time. The transmit power at
block 1006 may be set according to a peak mode (such as the peak
mode described herein with respect to FIG. 5B) if the transmit time
determined at block 1004 is greater than or equal to the time
window associated with the RF exposure limit. If the transmit time
associated with any of the plurality of transmit powers determined
at block 1004 is less than or equal to the time window and is
greater than or equal to the burst transmit time, the transmit
power at block 1006 may be set according to the time-average mode
such that the transmit power is less than or equal to the
instantaneous power limit and greater than the average power for a
first portion of the transmit time, and the transmit power at block
1006 may be less than the average power for a second portion of the
transmit time.
[0173] In certain aspects, the determination of the transmit times
may be determined under the assumption that current network
conditions remain the same throughout the transmission to the
receiving entity. In mobility conditions (e.g., when the UE is
moving within a wireless network and transmitting to one or more
receiving entities), the UE may use various models to estimate the
transmit time. For example, the UE may use machine learning to
predict/learn future network/radio conditions (e.g., a home-to-work
route), and the UE may compute the transmit time and/or select the
transmission mode at block 1004 using the predicted network/radio
conditions, for example to make a decision in selecting the
time-average mode, peak mode, a combination thereof, or one or more
other modes. With respect to the operations 1000A, the UE may
determine the transmit time under mobility conditions associated
with the UE based at least in part on future predicted radio
conditions. In some aspects, the future predicted radio conditions
may be generated with machine learning, artificial intelligence,
neural networks, regression analysis, etc. In some aspects, a
transmission mode is selected for the entirety of the data
transmission. In other aspects, a transmission mode may be selected
for each time window during which the data will be transmitted. For
example, when data is transmitted during two time windows, the UE
may select the peak mode and transmit a portion of the data using
the peak mode during a first of the two time windows, and may
select the time-average mode and transmit a remaining portion of
the data using the time-average mode during a second of the two
time windows. Those of skill in the art will appreciate that these
are examples only, and that the UE may make other selections or
other combinations of selections pursuant to the concepts described
herein.
[0174] In some aspects, the future/current radio conditions,
mobility conditions, buffer size, or other conditions described
herein with respect to the operation 1000A and/or the operations
1000B may be generated based on a pattern, for example as described
above with respect to FIGS. 6-9B, which may include parameters
associated with past network conditions, user behavior, etc. In
some aspects, a data or buffer size, data rate, transmission time,
etc. may be predicted or a determined value pertaining to one of
these aspects may be modified or revised based on a pattern. Thus,
the determining a transmit time in block 1004, or any other
operation described herein, may be based on a current or measured
value (e.g., data currently in a buffer, measured SNR, etc.) and/or
based on a predicted future value (e.g., additional data likely to
be received in the buffer within a time window, changing network
conditions, etc.), for example based on machine learning,
artificial intelligence, and known or determined pattern(s),
etc.
[0175] In some aspects, the RF exposure limit may be in compliance
with the limits set according to a regulatory/standards body (e.g.,
the Federal Communications Commission (FCC) for the United States;
the Innovation, Science and Economic Development Canada (ISED) for
Canada; or the International Commission on Non-Ionizing Radiation
Protection (ICNIRP) standard followed by the European Union (EU)).
The RF exposure limit may include a SAR limit and/or a PD limit for
various frequency ranges. The RF exposure limit may be averaged
over time for a specified time window, such as 4 seconds for
transmit frequencies between 24 GHz and 42 GHz, 100 seconds for
transmit frequencies less than 3 GHz, or 360 seconds for transmit
frequencies less than 6 GHz.
[0176] FIG. 10B is a flow diagram illustrating example operations
1000B for wireless communication, in accordance with certain
aspects of the present disclosure. The operations 1000B may be
performed, for example, by a UE (e.g., the UE 120a in the wireless
communication network 100).
[0177] The operations 1000B may begin, at block 1008, where the UE
may select a transmission mode from a plurality of transmission
modes (e.g., the time-average mode and peak mode) based on data for
a transmission from the UE to a receiving entity (e.g., the BS 110
and/or another UE 120) and one or more radio conditions associated
with the transmission. The data and/or radio conditions may be
current and/or measured, and/or future and/or predicted, e.g.,
using machine learning, artificial intelligence, and/or parameters
associated with past behavior and/or a pattern. At block 1010, the
UE may transmit, to the receiving entity, a signal indicative of
the data at a transmit power based at least in part on the selected
transmission mode and an RF exposure limit.
[0178] At block 1010 (or 1006), the UE may transmit at least a
portion of the data at a power level above an average power for the
RF exposure limit. At block 1010 (or 1006), the UE may transmit at
a reserve power level (e.g., the reserve power P.sub.reserve),
lower than the average power level, for at least a portion of a
time window in which the portion of the data was transmitted. In
certain aspects, the reserve power level may be adjusted, for
example, as further described herein.
[0179] The plurality of transmission modes may include at least a
first mode and a second mode, where the first mode includes
transmissions at levels above an average power for the RF exposure
limit and below the average power, and the second mode includes
transmissions at levels equal to or lower than the average power.
In other words, the first mode may correspond to the time-average
mode described herein with respect to FIG. 5C, and the second mode
may correspond to the peak mode described herein with respect to
FIG. 5B.
[0180] For certain aspects, the operations for determining the
transmit power described herein may take into account or consider
the transmission duty cycle, for example, in performing the
operations 600, operations 1000A, and/or operations 1000B. For
example, the burst transmit time of P(t) at P.sub.max can be scaled
by a transmission duty cycle. For short duty cycles, the transmit
power may be determined based on the duty cycle independently of
the operations 600, operations 1000A, and/or operations 1000B,
whereas for long duty cycles, the transmit power may be determined
according to the operations 600, operations 1000A, and/or
operations 1000B. For example, if the duty cycle is such that a
maximum exposure won't be reached regardless of the power used when
transmitting (e.g., because the amount of time during which
transmission power is zero will cause the average power to be less
than P.sub.limit), the UE may set the power to be P.sub.max when
transmitting (e.g., the time-average mode may be selected) even
when the burst transmit time is greater than the time window.
[0181] In certain aspects, the UE may adjust the reserve power
(P.sub.reserve) based on one or more criteria, in addition to or as
an alternative to the operations 600, operations 1000A, and/or
operations 1000B. For example, after deciding whether to perform
the time-average mode or peak mode in the operations 1000A and/or
operations 1000B, a certain transmit power behavior can be obtained
by adjusting the reserve power, such as increasing the reserve
power or decreasing the reserve power to a particular level. The
criteria used to adjust the reserve power may include machine
learning or artificial intelligence that is used to predict certain
future conditions (e.g., radio conditions, user behavior, mobility
conditions, etc.) and/or estimate current conditions (e.g., a
pattern described herein). The criteria may include a transmit time
associated with a transmission, for example, as described herein
with respect to the operations 1000A and/or operations 1000B. The
criteria may include a preferred transmit power behavior or
transmission mode, such as the peak mode depicted in FIG. 5B. The
criteria may include the conditions and/or patterns described
herein.
[0182] If the reserve power (P.sub.reserve) is set to P.sub.limit,
the transmission will perform similar to peak mode as depicted in
FIG. 5B, for example, in single transmission scenarios. If the
reserve power is increased, the duration for P.sub.max reduces, and
the duration for the reserve power increases, which may provide a
consistent transmit power over time. On the high side, instead of
setting the reserve power to P.sub.limit, the reserve power can be
set close to the P.sub.limit (e.g., 95% of the P.sub.limit) such
that 5% of energy can be used for high-power bursts at P.sub.max,
for example. In certain cases, any unused reserve power from a
radio in a multi-transmission scenario may be allocated as part of
the high-power burst margin or extra margin for other radios to
use. In some aspects, the reserve power may be defined and selected
in terms of certain states, such as high (e.g., 95% of
P.sub.limit), regular (e.g., 80% of P.sub.limit), and low (e.g.,
10% of P.sub.limit).
[0183] In certain aspects, the reserve power may be adjusted in
multi-transmission scenarios, for example, as described herein with
respect to FIG. 6. For example, suppose a first radio requests a
first reserve power and a second radio requests a second reserve
power. The total reserve power shared between the first and second
radios can be increased, if there is reserve power available after
accounting for the first and second reserve powers. For example,
the remaining reserve power (P.sub.delta) may be determined
according to the following expression:
P.sub.delta=max{P.sub.reserve_high-P.sub.reserve_radios,0} (17)
where P.sub.reserve_high may be set to a particular power level
less than or equal to P.sub.limit (e.g., 95% of P.sub.limit), and
P.sub.reserve_radios is equal to the sum of the reserve powers
selected for each of the radios (e.g., the sum of the first reserve
power for the first radio and the second reserve power for the
second radio). Since the P.sub.limit values may be different among
the radios in multi-transmission scenarios, Expression (17) could
be performed by normalizing all the quantities relative to
P.sub.limit of each radio. For example, P.sub.reserve high will be
replaced by a normalized reserve_high (e.g., =0.95),
P.sub.reserve_radios will be replaced by a normalized
reserve_radios (e.g., a sum of reserve powers selected for each of
the active radios, such as
0.90=P.sub.reserve1/P.sub.limit1+P.sub.reserve2/P.sub.limit2+ . . .
+P.sub.reserveN/P.sub.limitN), and P.sub.delta will be replaced by
a normalized delta (e.g., 0.05). The remaining reserve power
(P.sub.delta) may be divided among the radios to increase the
reserve powers for the respective radios. For example, the first
reserve power for the first radio may be increased by a portion of
P.sub.delta, and the second reserve power may be increased by the
remaining portion of P.sub.delta. A factor may be used to determine
the segmentation of the P.sub.delta, such as 1/(N radios). In
certain aspects, the reserve power may be segmented differently
across the radios, for example, based on an application or service
used for the radio.
[0184] FIGS. 11A-C are graphs 1100A-1100C of transmit powers over
time (P(t)) illustrating time-average modes that use a dynamic
reserve power, in accordance with certain aspects of the present
disclosure. Referring to FIG. 11A, the reserve power
(P.sub.reserve) may be set to zero or none, such that the longest
duration for P.sub.max is obtained in the time window (T).
Referring to FIG. 11B, the reserve power (P.sub.reserve) may be set
to a power level that is less than a certain value for the reserve
power (e.g., P.sub.reserve_reg). Referring to FIG. 11C, the reserve
power (P.sub.reserve) may be set to a power level that is above the
certain value for the reserve power (e.g., P.sub.reserve_reg).
[0185] Various aspects of the operations 1000B may be applied to
the operations 1000A, or vice versa. For example, the UE may
perform the selection at block 1008 based on the determined
transmit time(s) derived from the radio conditions, data size, data
rate, and/or specific transmit powers as described herein with
respect to block 1004. At block 1006 (or 1010), the UE may transmit
the signal based on the selected transmission mode associated with
block 1008. In certain aspects, the transmit power used for the
operation 1000A and/or operation 1000B may be set in conjunction
with another algorithm, such as the operations described herein
with respect to FIGS. 7A-9B, or performed independently from the
other algorithm. In some such examples, the transmit power may be
set lower than determined in operation 1000A or 1000B due to
application of an algorithm described with respect to FIGS.
7A-9B.
[0186] While various aspects of the present disclosure are
described herein with respect to selecting between the time-average
mode or peak mode based on an estimated transmit time to facilitate
understanding, aspects of the present disclosure may also be
applied to selecting other transmission modes, such as the simple
time-average mode or a combination of the time-average mode and
peak mode, based on the estimated transmit time and/or one or more
(radio) conditions. In some examples, a mode and/or transmit power
may be selected or determined (e.g., at block 604, 1004, 1008) so
as to maximize an amount of time during which a transmitting device
(e.g., the UE) transmits at or above P.sub.limit (or an amount of
power which is transmitted at or above P.sub.limit). For example,
if a burst or several bursts within a time window will be
sufficient to transmit data, the UE may determine to transmit the
burst(s) above P.sub.limit because there will be some time during
which transmission power would be zero regardless (such as when the
UE is done transmitting all the data) and transmitting above
P.sub.limit increases or maximizes the transmit power which is at
or above P.sub.limit. As another example, if transmitting a burst
would cause the UE to later reduce transmit power to be lower than
P.sub.limit (e.g., to P.sub.reserve), the UE may determine to
instead transmit all of the data at P.sub.limit so that it's not
later required to spend time transmitting below P.sub.limit.
[0187] While the examples depicted in FIGS. 1-11C are described
herein with respect to a UE performing the various methods for
providing RF exposure compliance to facilitate understanding,
aspects of the present disclosure may also be applied to other
wireless communication devices (wireless devices), such as a base
station and/or a CPE, performing the RF exposure compliance
described herein. Further, while the examples are described with
respect to communication between the UE (or other wireless device)
and a network entity, the UE or other wireless device may be
communicating with a device other than a network entity, for
example another UE or with another device in a user's home that is
not a network entity, for example.
[0188] FIG. 12 illustrates a communications device 1200 (e.g., the
UE 120) that may include various components (e.g., corresponding to
means-plus-function components) configured to perform operations
for the techniques disclosed herein, such as the operations
illustrated in FIGS. 6, 10A, and/or 10B. The communications device
1200 includes a processing system 1202 coupled to a transceiver
1208 (e.g., a transmitter and/or a receiver). The transceiver 1208
is configured to transmit and receive signals for the
communications device 1200 via an antenna 1210, such as the various
signals as described herein. The processing system 1202 may be
configured to perform processing functions for the communications
device 1200, including processing signals received and/or to be
transmitted by the communications device 1200.
[0189] The processing system 1202 includes a processor 1204 coupled
to a computer-readable medium/memory 1212 via a bus 1206. In
certain aspects, the computer-readable medium/memory 1212 is
configured to store instructions (e.g., computer-executable code)
that when executed by the processor 1204, cause the processor 1204
to perform the operations illustrated in FIG. 6, FIG. 10A, and/or
FIG. 10B, or other operations for performing the various techniques
discussed herein for providing RF exposure compliance. In certain
aspects, computer-readable medium/memory 1212 stores code for
obtaining 1214, code for determining or selecting (or allocating or
generating) 1216, code for transmitting 1218, code for selecting
1220, code for adjusting 1222, code for allocating 1224, and/or
code for generating 1226. In certain aspects, the processing system
1202 has circuitry 1228 configured to implement the code stored in
the computer-readable medium/memory 1212. In certain aspects, the
circuitry 1228 is coupled to the processor 1204 and/or the
computer-readable medium/memory 1212 via the bus 1206. For example,
the circuitry 1228 includes circuitry for obtaining 1230, circuitry
for determining or selecting (or allocating or generating) 1232,
circuitry for transmitting 1234, circuitry for selecting 1236,
circuitry for adjusting 1238, circuitry for allocating 1240, and/or
circuitry for generating 1242.
[0190] Various components of communications device 1200 may provide
means for performing the methods described herein, including with
respect to FIGS. 6-10B.
[0191] In some examples, means for transmitting or sending (or
means for outputting for transmission) may include the transceivers
254 and/or antenna(s) 252 of the UE 120 illustrated in FIG. 2
and/or transceiver 1208 and antenna 1210 of the communication
device 1200 in FIG. 12.
[0192] In some examples, means for receiving (or means for
obtaining) may include the transceivers 254 and/or antenna(s) 252
of the UE 120 illustrated in FIG. 2 and/or transceiver 1208 and
antenna 1210 of the communication device 1200 in FIG. 12.
[0193] In some examples, means for obtaining, means for
determining, means for selecting, means for adjusting, and/or means
for generating may include various processing system components,
such as: the one or more processors 1204 in FIG. 12, or aspects of
the UE 120 depicted in FIG. 2, including receive processor 258,
transmit processor 264, TX MIMO processor 266, and/or
controller/processor 280 (including RF exposure manager 281).
Example Aspects
[0194] In addition to the various aspects described above, specific
combinations of aspects are within the scope of the disclosure,
some of which are detailed below:
[0195] Aspect 1. A method of wireless communication by a user
equipment (UE), comprising: obtaining a pattern associated with one
or more first transmissions; determining a transmit power for one
or more second transmissions based at least in part on the pattern
and a radio frequency (RF) exposure limit; and transmitting the one
or more second transmissions at the determined transmit power.
[0196] Aspect 2. The method of Aspect 1, wherein the pattern
includes at least one of: a transmit power pattern; an antenna
usage pattern; a user behavior pattern; a transmission type; a
priority pattern; an application pattern; an application type; a
wireless network pattern; or a sensor information.
[0197] Aspect 3. The method of Aspect 2, wherein the transmit power
pattern includes one or more transmit powers over one or more time
windows associated with the RF exposure limit.
[0198] Aspect 4. The method according to Aspect 2 or 3, wherein the
antenna usage pattern includes indications over time when the UE
switched to a different transmission antenna.
[0199] Aspect 5. The method of Aspect 2, wherein the antenna usage
pattern includes a usage pattern for each radio among a plurality
of radios.
[0200] Aspect 6. The method of Aspect 2, wherein determining the
transmit power comprises: determining an overall available RF
exposure margin based on a usage pattern for each radio among a
plurality of radios; allocating an RF exposure margin to each of
the radios based on the overall available RF exposure margin;
determining a transmit power ceiling for one of the radios based on
the usage pattern for each of the other radios; and determining the
transmit power for the one or more second transmissions based at
least in part on the transmit power ceiling and the RF exposure
margin allocated to the one of the radios.
[0201] Aspect 7. The method of Aspect 2, wherein determining the
transmit power comprises: determining a transmit power ceiling for
a radio based on a usage pattern for the radio; and determining the
transmit power for the one or more second transmissions based at
least in part on the transmit power ceiling.
[0202] Aspect 8. The method of Aspect 7, wherein the transmit power
ceiling is less than a maximum transmit power supported by the UE
and greater than an average power limit associated with the RF
exposure limit.
[0203] Aspect 9. The method of Aspect 6, wherein the usage pattern
for each radio among the plurality of radios comprises an average
transmitted power in a past time interval associated with the
respective radio.
[0204] Aspect 10. The method of Aspect 6, wherein determining the
overall available RF exposure margin comprises determining a
difference between a maximum available usage and a sum of the usage
patterns for the radios.
[0205] Aspect 11. The method of Aspect 10, wherein allocating the
RF exposure margin comprises allocating a proportion of the overall
available RF exposure margin to each of the radios as the RF
exposure margin for the respective radio.
[0206] Aspect 12. The method of Aspect 11, wherein allocating the
proportion of the overall available RF exposure margin comprises
allocating the proportion of the overall available RF exposure
margin to each of the radios based at least in part on a priority
associated with at least one of the radios.
[0207] Aspect 13. The method of Aspect 12, wherein at least one of
the priority or the proportion of the overall available RF exposure
margin is associated with at least one of a frequency band, an
application, a service, a network condition, or an exposure
scenario associated with the at least one of the radios.
[0208] Aspect 14. The method of Aspect 10, wherein determining the
transmit power ceiling comprises determining a difference between
the maximum available usage and a sum of the usage patterns for
each of the other radios.
[0209] Aspect 15. The method of Aspect 6, wherein determining the
transmit power comprises determining the transmit power such that
the transmit power is less than or equal to a minimum of the
transmit power ceiling and the RF exposure margin allocated to the
one of the radios.
[0210] Aspect 16. The method of Aspect 6, wherein determining the
transmit power comprises adjusting the transmit power ceiling in
response to a change in the usage pattern for the radios.
[0211] Aspect 17. The method of Aspect 7, wherein determining the
transmit power comprises adjusting the transmit power ceiling in
response to a change in the usage pattern for the radio.
[0212] Aspect 18. The method of Aspect 16, wherein adjusting the
transmit power ceiling comprises adjusting the transmit power
ceiling in response to a change in a transmission scenario
associated with the radios.
[0213] Aspect 19. The method of Aspect 16, wherein adjusting the
transmit power ceiling comprises adjusting the transmit power
ceiling based at least in part on a traffic model.
[0214] Aspect 20. The method according to Aspect 6 or 7, wherein
transmitting the one or more second transmissions comprises
transmitting the one or more second transmissions at the transmit
power ceiling for a first portion of a time window associated with
the RF exposure limit and transmitting the one or more second
transmissions at another transmit power less than the transmit
power ceiling for a second portion of the time window.
[0215] Aspect 16. The method according to any of Aspects 2-15,
wherein the user behavior pattern includes one or more times
associated with when a user uses the UE for wireless
communications.
[0216] Aspect 17. The method according to any of Aspects 2-16,
wherein the application pattern includes at least one of one or
more transmit times or one or more transmit powers associated with
one or more applications.
[0217] Aspect 18. The method according to any of Aspects 2-17,
wherein the application type indicates a kind of application that
generates data for transmission.
[0218] Aspect 19. The method of Aspect 18, wherein determining the
transmit power comprises: determining the application type for the
one or more second transmissions; and determining the transmit
power based on the application type having priority over other
application types.
[0219] Aspect 20. The method according to any of Aspects 2-19,
wherein the wireless network pattern includes at least one of: a
channel quality between the UE and a receiving entity; a modulation
and coding scheme (MCS) associated with the one or more first
transmissions; a coding rate associated with the one or more first
transmissions; a periodicity associated with the one or more first
transmissions; a duty cycle associated with the one or more first
transmissions; or an indication of the UE's mobility during the one
or more first transmissions.
[0220] Aspect 21. The method according to any of Aspects 2-20,
wherein the sensor information pattern includes at least one of an
indication of the UE's proximity to a non-human object, an
indication that the UE is in free space, an indication of a user
usage scenario, an indication of a usage state of the UE, or an
indication of when antenna switching occurs at the UE.
[0221] Aspect 22. The method of Aspect 21, wherein the user usage
scenario indicates to which portion of user's body the UE is in
proximity.
[0222] Aspect 23. The method according to any of Aspects 1-22,
wherein determining the transmit power comprises determining the
transmit power with machine learning based at least in part on the
pattern.
[0223] Aspect 24. The method of Aspect 23, wherein determining the
transmit power comprises: generating upcoming user behavior with
machine learning; and determining the transmit power based on the
upcoming user behavior and current network conditions.
[0224] Aspect 25. The method of Aspect 23, wherein determining the
transmit power comprises: generating upcoming network conditions
with machine learning; and determining the transmit power based on
current user behavior and the upcoming network conditions.
[0225] Aspect 26. The method of Aspect 23, wherein determining the
transmit power comprises: generating upcoming network conditions
and upcoming user behavior with machine learning; and determining
the transmit power based on the upcoming network conditions and the
upcoming user behavior.
[0226] Aspect 27. The method according to any of Aspects 1-26,
wherein determining the transmit power comprises: correlating the
pattern to a transmit time associated with the one or more second
transmissions; comparing the transmit time to a time window
associated with the RF exposure limit; and determining the transmit
power based on the comparison.
[0227] Aspect 28. The method according to any of Aspects 1-27,
wherein the RF exposure limit comprises a specific absorption rate
(SAR) limit, a power density (PD) limit, or a combination
thereof.
[0228] Aspect 29. The method according to any of Aspects 1-28,
wherein at least one of the one or more first transmissions
occurred at a time prior to a current time window used for
determining the transmit power based on the RF exposure limit.
[0229] Aspect 30. The method according to any of Aspects 1-29,
wherein the determining comprises determining the transmit power to
be a power above an average power level when the pattern indicates
that RF exposure margin is likely to be available, and determining
the transmit power to be the average power level otherwise.
[0230] Aspect 31. The method of Aspect 30, wherein determining the
transmit power to be a power above the average power level further
comprises determining that a network condition indicates higher
transmission power would be beneficial or determining that high
priority information is being transmitted.
[0231] Aspect 32. The method according to any of Aspects 1-31,
wherein the determining comprises comparing data stored in a
transmit buffer to usage predicted based on the pattern or
comparing transmit power used to transmit the data in the data
buffer to a transmit power predicted based on the pattern.
[0232] Aspect 34. An apparatus for wireless communication,
comprising: a memory; a processor coupled to the memory, the
processor and the memory being configured to: obtain a pattern
associated with one or more first transmissions, and determine a
transmit power for one or more second transmissions based at least
in part on the pattern and an RF exposure limit; and a transmitter
configured to transmit the one or more second transmissions at the
determined transmit power.
[0233] Aspect 35. The apparatus of Aspect 34, the apparatus being
configured to perform any of Aspects 1 through 32.
[0234] Aspect 36. An apparatus for wireless communication,
comprising: means for obtaining a pattern associated with one or
more first transmissions; means for determining a transmit power
for one or more second transmissions based at least in part on the
pattern and an RF exposure limit; and means for transmitting the
one or more second transmissions at the determined transmit
power.
[0235] Aspect 37. The apparatus of Aspect 36, the apparatus
comprising means for performing any of Aspects 1 through 32.
[0236] Aspect 38. A computer-readable medium having instructions
stored thereon for: obtaining a pattern associated with one or more
first transmissions; determining a transmit power for one or more
second transmissions based at least in part on the pattern and an
RF exposure limit; and transmitting the one or more second
transmissions at the determined transmit power.
[0237] Aspect 39. The computer-readable medium of Aspect 38, the
computer-readable medium having instructions stored thereon for
performing any of Aspects 1 through 32.
[0238] In addition to the various aspects described above, specific
combinations of aspects are within the scope of the disclosure,
some of which are detailed below:
[0239] Aspect 1: An apparatus for wireless communication,
comprising: a memory; and a processor coupled to the memory, the
processor and the memory being configured to: obtain a pattern
associated with one or more first transmissions, determine a
transmit power for one or more second transmissions based at least
in part on the pattern and a radio frequency (RF) exposure limit,
and transmit the one or more second transmissions at the determined
transmit power.
[0240] Aspect 2: The apparatus of Aspect 1, wherein the pattern
includes at least one of: a transmit power pattern; an antenna
usage pattern; a user behavior pattern; a transmission type; a
priority pattern; an application pattern; an application type; a
wireless network pattern; or a sensor information.
[0241] Aspect 3: The apparatus according to Aspect 1 or 2, wherein
the processor and the memory are further configured to: determine a
first transmit power; determine a second transmit power based at
least in part on average transmitted power over a time interval;
select a third transmit power as a minimum of the first transmit
power and the second transmit power; and determine the transmit
power for the one or more second transmissions such that the
transmit power is less than or equal to the third transmit
power.
[0242] Aspect 4: The apparatus of Aspect 3, wherein the second
transmit power is based at least in part on a reciprocal of a
normalized average transmitted power in a past time interval.
[0243] Aspect 5: The apparatus according to any of Aspects 1-4,
wherein the processor and the memory are further configured to:
determine a first transmit power for each of a plurality of radios;
determine a second transmit power for each of the plurality of
radios, wherein the second transmit power is based at least in part
on a normalized average transmitted power for the respective radio
over a time interval; select a third transmit power for each of the
plurality of radios as a minimum of the first transmit power and
the second transmit power for the respective radio; and determine
the transmit power for the one or more second transmissions such
that the transmit power for each of the plurality of radios is less
than or equal to the third transmit power for the respective
radio.
[0244] Aspect 6: The apparatus of Aspect 5, wherein the processor
and the memory are further configured to: determine a fourth
transmit power based at least in part on a product between a
maximum average power corresponding to the RF exposure limit for
the respective radio and a reciprocal of a sum of minimums of a
normalized average transmitted power for the plurality of radios
and unity, wherein the fourth transmit power is further based on a
proportion between the normalized average transmitted power for the
respective radio and a total of the normalized average transmitted
powers for the plurality of radios; determine a fifth transmit
power that is the maximum average power corresponding to the RF
exposure limit divided by a number of the plurality of radios; and
select the second transmit power based on a maximum of the fourth
transmit power and the fifth transmit power.
[0245] Aspect 7: The apparatus according to Aspect 5 or 6, wherein
the processor and the memory are further configured to: adjust the
time interval for the normalized average transmitted power based at
least in part on an average power over a time window corresponding
to the RF exposure limit; and select, as the time interval, a
maximum among a first time interval and a second time interval
varying with average transmitted power over a past time window,
wherein the first time interval and the second time interval depend
on a transmission frequency of the one or more second
transmissions.
[0246] Aspect 8: The apparatus according to any of Aspects 5-7,
wherein the processor and the memory are further configured to
adjust the time interval for the normalized average transmitted
power based at least in part on one or more current network
conditions.
[0247] Aspect 9: The apparatus according to any of Aspects 1-8,
wherein the processor and the memory are further configured to:
determine a first transmit power; apply a cap to the first transmit
power to determine a second transmit power; and determine the
transmit power for the one or more second transmissions such that
the transmit power is less than or equal to the second transmit
power.
[0248] Aspect 10: The apparatus according to any of Aspects 1-9,
wherein the processor and the memory are further configured to:
determine a first transmit power for the one or more second
transmissions based at least in part on a time-averaged RF exposure
in a past time window; determine a second transmit power based at
least in part on a normalized average transmitted power for a radio
over a time interval; determine a third transmit power that is a
maximum average power corresponding to the RF exposure limit;
select a fourth transmit power as a minimum of the first transmit
power and the second transmit power for the radio; select a fifth
transmit power as a minimum of the first transmit power and the
third transmit power for the radio; select a sixth transmit power
among the first transmit power, the fourth transmit power, and the
fifth transmit power; and determine the transmit power for the one
or more second transmissions such that the transmit power is less
than or equal to the sixth transmit power for the radio.
[0249] Aspect 11: The apparatus according to any of Aspects 1-10,
wherein the processor and the memory are further configured to:
determine a first transmit power for each of a plurality of radios,
wherein the first transmit power is based at least in part on a
time-averaged RF exposure in a past time window; determine a second
transmit power for each of the plurality of radios, wherein the
second transmit power is based at least in part on a normalized
average transmitted power for the respective radio over a time
interval; determine a third transmit power for each of the
plurality of radios, wherein the third transmit power is a maximum
average power corresponding to the RF exposure limit divided by a
number of the plurality of radios; select a fourth transmit power
for each of the plurality of radios as a minimum of the first
transmit power and the second transmit power for the respective
radio; select a fifth transmit power for each of the plurality of
radios as a minimum of the first transmit power and the third
transmit power for the respective radio; select a sixth transmit
power for each of the plurality of radios among the first transmit
power, the fourth transmit power, and the fifth transmit power for
the respective radio; and determine the transmit power for the one
or more second transmissions such that the transmit power for each
of the plurality of radios is less than or equal to the sixth
transmit power for the respective radio.
[0250] Aspect 12: The apparatus according to any of Aspects 2-11,
wherein the processor and the memory are further configured to:
determine an overall available RF exposure margin based on a usage
pattern for each radio among a plurality of radios; allocate an RF
exposure margin to each of the radios based on the overall
available RF exposure margin; determine a transmit power ceiling
for one of the radios based on the usage pattern for each of the
other radios; and determine the transmit power for the one or more
second transmissions based at least in part on the transmit power
ceiling and the RF exposure margin allocated to the one of the
radios.
[0251] Aspect 13: The apparatus according to any of Aspects 2-12,
wherein the processor and the memory are further configured to:
determine a transmit power ceiling for a radio based on a usage
pattern for a radio; and determine the transmit power for the one
or more second transmissions based at least in part on the transmit
power ceiling, wherein the transmit power ceiling is less than a
maximum transmit power supported by the apparatus and greater than
an average power limit associated with the RF exposure limit.
[0252] Aspect 14: The apparatus according to Aspect 12 or 13,
wherein the usage pattern for each radio among the plurality of
radios comprises an average transmitted power in a past time
interval associated with the respective radio.
[0253] Aspect 15: The apparatus according to any of Aspects 12-14,
wherein the processor and the memory are further configured to
determine, as the overall available RF exposure margin, a
difference of a maximum available usage and a sum of the usage
patterns for the radios.
[0254] Aspect 16: The apparatus of Aspect 15, wherein the processor
and the memory are further configured to: allocate a proportion of
the overall available RF exposure margin to each of the radios as
the RF exposure margin for the respective radio; allocate the
proportion of the overall available RF exposure margin to each of
the radios based at least in part on a priority associated with at
least one of the radios; and determine, as the transmit power
ceiling, a difference of the maximum available usage and a sum of
the usage patterns for each of the other radios.
[0255] Aspect 17: The apparatus of Aspect 16, wherein at least one
of a priority or the proportion of the overall available RF
exposure margin is associated with at least one of a frequency
band, an application, a service, a network condition, or an
exposure scenario associated with the at least one of the
radios.
[0256] Aspect 18: The apparatus according to any of Aspects 12-17,
wherein the processor and the memory are further configured to
determine the transmit power such that the transmit power is less
than or equal to a minimum of the transmit power ceiling and the RF
exposure margin allocated to the one of the radios.
[0257] Aspect 19: The apparatus according to any of Aspects 12-18,
wherein the processor and the memory are further configured to
adjust the transmit power ceiling in response to a change in the
usage pattern for the radios.
[0258] Aspect 20: The apparatus according to any of Aspects 2-19,
wherein the processor and the memory are further configured to:
determine the application type for the one or more second
transmissions; and determine the transmit power based on the
application type having priority over other application types.
[0259] Aspect 21: The apparatus according to any of Aspects 1-20,
wherein the processor and the memory are further configured to
determine the transmit power with machine learning based at least
in part on the pattern.
[0260] Aspect 22: The apparatus of Aspect 21, wherein the processor
and the memory are further configured to: generate at least one of
upcoming user behavior or upcoming network conditions with machine
learning; and determine the transmit power based on at least one of
the upcoming user behavior, current user behavior, the upcoming
network conditions, or current network conditions.
[0261] Aspect 23: The apparatus according to any of Aspects 1-22,
wherein the processor and the memory are further configured to:
correlate the pattern to a transmit time associated with the one or
more second transmissions; compare the transmit time to a time
window associated with the RF exposure limit; and determine the
transmit power based on the comparison.
[0262] Aspect 24: The apparatus according to any of Aspects 2-23,
wherein: the transmit power pattern includes one or more transmit
powers over one or more time windows associated with the RF
exposure limit; the antenna usage pattern includes a usage pattern
for each radio among a plurality of radios; the user behavior
pattern includes one or more times associated with when a user uses
the apparatus for wireless communications; the application pattern
includes at least one of one or more transmit times or one or more
transmit powers associated with one or more applications; the
application type indicates a kind of application that generates
data for transmission; the wireless network pattern includes at
least one of: a channel quality between the apparatus and a
receiving entity; a modulation and coding scheme (MCS) associated
with the one or more first transmissions; a coding rate associated
with the one or more first transmissions; a periodicity associated
with the one or more first transmissions; a duty cycle associated
with the one or more first transmissions; or an indication of the
apparatus's mobility during the one or more first transmissions;
the sensor information includes at least one of an indication of
the apparatus's proximity to a non-human object, an indication that
the apparatus is in free space, an indication of a user usage
scenario, an indication of a usage state of the apparatus, or an
indication of when antenna switching occurs at the apparatus; and
the user usage scenario indicates to which portion of a user's body
the apparatus is in proximity.
[0263] Aspect 25: The apparatus according to any of Aspects 1-24,
wherein the RF exposure limit comprises a specific absorption rate
(SAR) limit, a power density (PD) limit, or a combination
thereof.
[0264] Aspect 26: A method of wireless communication by a wireless
device, comprising: obtaining a pattern associated with one or more
first transmissions; determining a transmit power for one or more
second transmissions based at least in part on the pattern and a
radio frequency (RF) exposure limit; and transmitting the one or
more second transmissions at the determined transmit power.
[0265] Aspect 27: The method of Aspect 26, wherein the pattern
includes at least one of: a transmit power pattern; an antenna
usage pattern; a user behavior pattern; a transmission type; a
priority pattern; an application pattern; an application type; a
wireless network pattern; or a sensor information.
[0266] Aspect 28: The method according to Aspect 26 or 27, wherein
determining the transmit power comprises: determining a first
transmit power for each of a plurality of radios; determining a
second transmit power for each of the plurality of radios, wherein
the second transmit power is based at least in part on a normalized
average transmitted power for the respective radio over a time
interval; selecting a third transmit power for each of the
plurality of radios as a minimum of the first transmit power and
the second transmit power for the respective radio; and determining
the transmit power for the one or more second transmissions such
that the transmit power for each of the plurality of radios is less
than or equal to the third transmit power for the respective
radio.
[0267] Aspect 29: The method according to Aspect 27 or 28, wherein
determining the transmit power comprises: determining an overall
available RF exposure margin based on a usage pattern for each
radio among a plurality of radios; allocating an RF exposure margin
to each of the radios based on the overall available RF exposure
margin; determining a transmit power ceiling for one of the radios
based on the usage pattern for each of the other radios; and
determining the transmit power for the one or more second
transmissions based at least in part on the transmit power ceiling
and the RF exposure margin allocated to the one of the radios.
[0268] Aspect 30: The method according to any of Aspects 27-29,
wherein determining the transmit power comprises: determining a
transmit power ceiling for a radio based on a usage pattern for a
radio; and determining the transmit power for the one or more
second transmissions based at least in part on the transmit power
ceiling, wherein the transmit power ceiling is less than a maximum
transmit power supported by the wireless device and greater than an
average power limit associated with the RF exposure limit.
[0269] Aspect 31: An apparatus for wireless communication,
comprising: a memory; and a processor coupled to the memory, the
processor and the memory being configured to: obtain data for a
transmission to a receiving entity and radio conditions associated
with the transmission, determine a transmit time associated with
the data based at least in part on the radio conditions, and
transmit, to the receiving entity, a signal indicative of the data
at a transmit power based at least in part on the determined
transmit time and a radio frequency (RF) exposure limit.
[0270] Aspect 32: The apparatus of Aspect 31, wherein: the transmit
time is selected from a plurality of transmit times associated with
a plurality of transmit powers; and the plurality of transmit
powers includes the transmit power at which the signal is
transmitted.
[0271] Aspect 33: The apparatus of Aspect 32, wherein the plurality
of transmit times comprises a first transmit time associated with
an instantaneous power limit supported by the apparatus and a
second transmit time associated with an average power corresponding
to the RF exposure limit.
[0272] Aspect 34: The apparatus of Aspect 33, wherein: the transmit
power is limited by the instantaneous power limit if the first
transmit time is less than or equal to a burst transmit time
associated with the instantaneous power limit in compliance with
the RF exposure limit, wherein the burst transmit time is less than
a time window associated with the RF exposure limit; the transmit
power is limited by the average power if the second transmit time
is greater than or equal to the time window associated with the RF
exposure limit; and if the transmit time associated with any of the
plurality of transmit powers is less than or equal to the time
window, and is greater than or equal to the burst transmit time,
the transmit power is less than or equal to the instantaneous power
limit and greater than the average power for a first portion of the
transmit time, and the transmit power is less than the average
power for a second portion of the transmit time.
[0273] Aspect 35: The apparatus according to Aspect 33 or 34,
wherein: the transmit power is set according to a time-average mode
if the transmit time is less than or equal to a burst transmit time
associated with the instantaneous power limit in compliance with
the RF exposure limit, wherein the burst transmit time is less than
a time window associated with the RF exposure limit; the transmit
power is set according to a peak mode if the transmit time is
greater than or equal to the time window associated with the RF
exposure limit; and if the transmit time associated with any of the
plurality of transmit powers is less than or equal to the time
window and is greater than or equal to the burst transmit time, the
transmit power is set according to the time-average mode such that
the transmit power is less than or equal to the instantaneous power
limit and greater than the average power for a first portion of the
transmit time, and the transmit power is less than the average
power for a second portion of the transmit time.
[0274] Aspect 36: The apparatus according to any of Aspects 31-35,
wherein the radio conditions include at least one of: a channel
quality between the apparatus and the receiving entity; a
modulation and coding scheme (MCS) associated with the
transmission; a coding rate associated with the transmission; or a
periodicity associated with transmissions to the receiving
entity.
[0275] Aspect 37: The apparatus according to any of Aspects 31-36,
wherein the processor and the memory are further configured to:
determine a data rate associated with transmitting the data to the
receiving entity based on the radio conditions; and determine the
transmit time based on the data rate and a size associated with the
data.
[0276] Aspect 38: The apparatus according to any of Aspects 31-37,
wherein the processor and the memory are further configured to
determine the transmit time under mobility conditions associated
with the apparatus based at least in part on future predicted radio
conditions.
[0277] Aspect 39: The apparatus of Aspect 38, wherein the processor
and the memory are further configured to generate the future
predicted radio conditions with machine learning.
[0278] Aspect 40: The apparatus according to any of Aspects 31-39,
wherein the processor and the memory are further configured to
determine the transmit time based at least in part on a buffer size
associated with the data.
[0279] Aspect 41: The apparatus according to any of Aspects 31-40,
wherein the processor and the memory are configured to determine
the radio conditions based on a pattern associated with a first
time window, wherein the first time window is separate from a
second time window associated with the RF exposure limit.
[0280] Aspect 42: An apparatus for wireless communication,
comprising: a memory; and a processor coupled to the memory, the
processor and the memory are further configured to: select a
transmission mode from a plurality of transmission modes based on
data for a transmission from the apparatus to a receiving entity
and one or more radio conditions associated with the transmission,
and transmit, to the receiving entity, a signal indicative of the
data at a transmit power based at least in part on the selected
transmission mode and a radio frequency (RF) exposure limit.
[0281] Aspect 43: The apparatus of Aspect 42, wherein the processor
and the memory are further configured to transmit at least a
portion of the data at a power level above an average power level
for the RF exposure limit.
[0282] Aspect 44: The apparatus of Aspect 43, wherein the processor
and the memory are configured to transmit at the power level above
the average power level for the RF exposure limit during a time
window associated with the RF exposure limit based on a duty cycle
for the transmission.
[0283] Aspect 45: The apparatus according to Aspect 43 or 44,
wherein the processor and the memory are further configured to
transmit at a reserve power level, lower than the average power
level, for at least a portion of a time window in which the portion
of the data was transmitted.
[0284] Aspect 46: The apparatus of Aspect 45, wherein the processor
and the memory are further configured to adjust the reserve power
level.
[0285] Aspect 47: The apparatus according to any of Aspects 42-46,
wherein: the plurality of transmission modes includes at least a
first mode and a second mode, the first mode including
transmissions at power levels above an average power level for the
RF exposure limit and below the average power level, and the second
mode including transmissions at power levels equal to or lower than
the average power level; and the one or more radio conditions
include at least one of: a channel quality between the apparatus
and a receiving entity; a modulation and coding scheme (MCS)
associated with the transmission; a coding rate associated with the
transmission; or a periodicity associated with transmissions to the
receiving entity.
[0286] Aspect 48: A method of wireless communication by a wireless
device, comprising: obtaining data for a transmission to a
receiving entity and radio conditions associated with the
transmission; determining a transmit time associated with the data
based at least in part on the radio conditions; and transmitting,
to the receiving entity, a signal indicative of the data at a
transmit power based at least in part on the determined transmit
time and a radio frequency (RF) exposure limit.
[0287] Aspect 49: The method of Aspect 48, wherein: the transmit
time is selected from a plurality of transmit times associated with
a plurality of transmit powers; and the plurality of transmit
powers includes the transmit power at which the signal is
transmitted, wherein the plurality of transmit times comprises a
first transmit time associated with an instantaneous power limit
supported by the wireless device and a second transmit time
associated with an average power corresponding to the RF exposure
limit.
[0288] Aspect 50: The method of Aspect 49, wherein: the transmit
power is limited by the instantaneous power limit if the first
transmit time is less than or equal to a burst transmit time
associated with the instantaneous power limit in compliance with
the RF exposure limit, wherein the burst transmit time is less than
a time window associated with the RF exposure limit; the transmit
power is limited by the average power if the second transmit time
is greater than or equal to the time window associated with the RF
exposure limit; and if the transmit time associated with any of the
plurality of transmit powers is less than or equal to the time
window, and is greater than or equal to the burst transmit time,
the transmit power is less than or equal to the instantaneous power
limit and greater than the average power for a first portion of the
transmit time, and the transmit power is less than the average
power for a second portion of the transmit time.
[0289] Aspect 51: The method according to Aspect 49 or 50, wherein:
the transmit power is set according to a time-average mode if the
transmit time is less than or equal to a burst transmit time
associated with the instantaneous power limit in compliance with
the RF exposure limit, the burst transmit time being less than a
time window associated with the RF exposure limit; the transmit
power is set according to a peak mode if the transmit time is
greater than or equal to the time window associated with the RF
exposure limit; and if the transmit time associated with any of the
plurality of transmit powers is less than or equal to the time
window and is greater than or equal to the burst transmit time, the
transmit power is set according to the time-average mode such that
the transmit power is less than or equal to the instantaneous power
limit and greater than the average power for a first portion of the
transmit time, and the transmit power is less than the average
power for a second portion of the transmit time.
[0290] Aspect 52: The method according to any of Aspects 48-51,
wherein the radio conditions include at least one of: a channel
quality between the wireless device and the receiving entity; a
modulation and coding scheme (MCS) associated with the
transmission; a coding rate associated with the transmission; or a
periodicity associated with transmissions to the receiving
entity.
[0291] Aspect 53: The method according to any of Aspects 48-52,
wherein determining the transmit time comprises: determining a data
rate associated with transmitting the data to the receiving entity
based on the radio conditions; and determining the transmit time
based on the data rate and a size associated with the data.
[0292] Aspect 54: The method according to any of Aspects 48-53,
wherein determining the transmit time comprises determining the
transmit time under mobility conditions associated with the
wireless device based at least in part on future predicted radio
conditions.
[0293] Aspect 55: The method according to any of Aspects 48-54,
wherein determining the transmit time comprises determining the
transmit time based at least in part on a buffer size associated
with the data.
[0294] Aspect 56: A method of wireless communication by a wireless
device, comprising: selecting a transmission mode from a plurality
of transmission modes based on data for a transmission from the
wireless device to a receiving entity and one or more radio
conditions associated with the transmission; and transmitting, to
the receiving entity, a signal indicative of the data at a transmit
power based at least in part on the selected transmission mode and
a radio frequency (RF) exposure limit.
[0295] Aspect 57: The method of Aspect 56, wherein the transmitting
comprises transmitting at least a portion of the data at a power
level above an average power level for the RF exposure limit.
[0296] Aspect 58: The method of Aspect 57, wherein the transmitting
comprises transmitting at a reserve power level, lower than the
average power level, for at least a portion of a time window in
which the portion of the data was transmitted.
[0297] Aspect 59: The method of Aspect 58, wherein the transmitting
comprises adjusting the reserve power level.
[0298] Aspect 60: The method according to any of Aspects 56-59,
wherein: the plurality of transmission modes includes at least a
first mode and a second mode, the first mode including
transmissions at power levels above an average power level for the
RF exposure limit and below the average power level, and the second
mode including transmissions at power levels equal to or lower than
the average power level; and the one or more radio conditions
include at least one of: a channel quality between the wireless
device and the receiving entity; a modulation and coding scheme
(MCS) associated with the transmission; a coding rate associated
with the transmission; or a periodicity associated with
transmissions to the receiving entity.
[0299] Aspect 61: An apparatus comprising: a memory comprising
executable instructions; one or more processors configured to
execute the executable instructions and cause the apparatus to
perform a method in accordance with any of Aspects 26-30 or
48-60.
[0300] Aspect 62: An apparatus comprising means for performing a
method in accordance with any of Aspects 26-30 or 48-60.
[0301] Aspect 63: A computer-readable medium comprising executable
instructions that, when executed by one or more processors of an
apparatus, cause the apparatus to perform a method in accordance
with any of Aspects 26-30 or 48-60.
[0302] Aspect 64: A computer program product embodied on a
computer-readable storage medium comprising code for performing a
method in accordance with any of Aspects 26-30 or 48-60.
[0303] The techniques described herein may be used for various
wireless communication technologies, such as NR (e.g., 5G NR), 3GPP
Long Term Evolution (LTE), LTE-Advanced (LTE-A), code division
multiple access (CDMA), time division multiple access (TDMA),
frequency division multiple access (FDMA), orthogonal frequency
division multiple access (OFDMA), single-carrier frequency division
multiple access (SC-FDMA), time division synchronous code division
multiple access (TD-SCDMA), and other networks. The terms "network"
and "system" are often used interchangeably. A CDMA network may
implement a radio technology such as Universal Terrestrial Radio
Access (UTRA), cdma2000, etc. UTRA includes Wideband CDMA (WCDMA)
and other variants of CDMA. cdma2000 covers IS-2000, IS-95 and
IS-856 standards. A TDMA network may implement a radio technology
such as Global System for Mobile Communications (GSM). An OFDMA
network may implement a radio technology such as NR (e.g. 5G RA),
Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11
(Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc. UTRA
and E-UTRA are part of Universal Mobile Telecommunication System
(UMTS). LTE and LTE-A are releases of UMTS that use E-UTRA. UTRA,
E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents from an
organization named "3rd Generation Partnership Project" (3GPP).
cdma2000 and UMB are described in documents from an organization
named "3rd Generation Partnership Project 2" (3GPP2). NR is an
emerging wireless communications technology under development.
[0304] In 3GPP, the term "cell" can refer to a coverage area of a
Node B (NB) and/or a NB subsystem serving this coverage area,
depending on the context in which the term is used. In NR systems,
the term "cell" and BS, next generation NodeB (gNB or gNodeB),
access point (AP), distributed unit (DU), carrier, or transmission
reception point (TRP) may be used interchangeably. A BS may provide
communication coverage for a macro cell, a pico cell, a femto cell,
and/or other types of cells. A macro cell may cover a relatively
large geographic area (e.g., several kilometers in radius) and may
allow unrestricted access by UEs with service subscription. A pico
cell may cover a relatively small geographic area and may allow
unrestricted access by UEs with service subscription. A femto cell
may cover a relatively small geographic area (e.g., a home) and may
allow restricted access by UEs having an association with the femto
cell (e.g., UEs in a closed subscriber group (CSG), UEs for users
in the home, etc.). A BS for a macro cell may be referred to as a
macro BS. A BS for a pico cell may be referred to as a pico BS. A
BS for a femto cell may be referred to as a femto BS or a home
BS.
[0305] A UE may also be referred to as a mobile station, a
terminal, an access terminal, a subscriber unit, a station, a
Customer Premises Equipment (CPE), a cellular phone, a smartphone,
a personal digital assistant (PDA), a wireless modem, a wireless
communication device, a handheld device, a laptop computer, a
cordless phone, a wireless local loop (WLL) station, a tablet
computer, a camera, a gaming device, a netbook, a smartbook, an
ultrabook, an appliance, a medical device or medical equipment, a
biometric sensor/device, a wearable device such as a smart watch,
smart clothing, smart glasses, a smart wrist band, smart jewelry
(e.g., a smart ring, a smart bracelet, etc.), an entertainment
device (e.g., a music device, a video device, a satellite radio,
etc.), a vehicular component or sensor, a smart meter/sensor,
industrial manufacturing equipment, a global positioning system
(GPS) device, or any other suitable device that is configured to
communicate via a wireless or wired medium. Some UEs may be
considered machine-type communication (MTC) devices or evolved MTC
(eMTC) devices. MTC and eMTC UEs include, for example, robots,
drones, remote devices, sensors, meters, monitors, location tags,
etc., that may communicate with a BS, another device (e.g., remote
device), or some other entity. A wireless node may provide, for
example, connectivity for or to a network (e.g., a wide area
network such as Internet or a cellular network) via a wired or
wireless communication link. Some UEs may be considered
Internet-of-Things (IoT) devices, which may be narrowband IoT
(NB-IoT) devices.
[0306] In some examples, access to the air interface may be
scheduled. A scheduling entity (e.g., a BS) allocates resources for
communication among some or all devices and equipment within its
service area or cell. The scheduling entity may be responsible for
scheduling, assigning, reconfiguring, and releasing resources for
one or more subordinate entities. That is, for scheduled
communication, subordinate entities utilize resources allocated by
the scheduling entity. Base stations are not the only entities that
may function as a scheduling entity. In some examples, a UE may
function as a scheduling entity and may schedule resources for one
or more subordinate entities (e.g., one or more other UEs), and the
other UEs may utilize the resources scheduled by the UE for
wireless communication. In some examples, a UE may function as a
scheduling entity in a peer-to-peer (P2P) network, and/or in a mesh
network. In a mesh network example, UEs may communicate directly
with one another in addition to communicating with a scheduling
entity.
[0307] The methods disclosed herein comprise one or more steps or
actions for achieving the methods. The method steps and/or actions
may be interchanged with one another without departing from the
scope of the claims. In other words, unless a specific order of
steps or actions is specified, the order and/or use of specific
steps and/or actions may be modified without departing from the
scope of the claims.
[0308] As used herein, a phrase referring to "at least one of" a
list of items refers to any combination of those items, including
single members. As an example, "at least one of: a, b, or c" is
intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any
combination with multiples of the same element (e.g., a-a, a-a-a,
a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or
any other ordering of a, b, and c).
[0309] As used herein, the term "determining" encompasses a wide
variety of actions. For example, "determining" may include
calculating, computing, processing, deriving, investigating,
looking up (e.g., looking up in a table, a database or another data
structure), ascertaining and the like. Also, "determining" may
include receiving (e.g., receiving information), accessing (e.g.,
accessing data in a memory) and the like. Also, "determining" may
include resolving, selecting, choosing, establishing, and the
like.
[0310] The previous description is provided to enable any person
skilled in the art to practice the various aspects described
herein. Various modifications to these aspects will be readily
apparent to those skilled in the art, and the generic principles
defined herein may be applied to other aspects. Thus, the claims
are not intended to be limited to the aspects shown herein, but is
to be accorded the full scope consistent with the language of the
claims, wherein reference to an element in the singular is not
intended to mean "one and only one" unless specifically so stated,
but rather "one or more." Unless specifically stated otherwise, the
term "some" refers to one or more. All structural and functional
equivalents to the elements of the various aspects described
throughout this disclosure that are known or later come to be known
to those of ordinary skill in the art are expressly incorporated
herein by reference and are intended to be encompassed by the
claims. Moreover, nothing disclosed herein is intended to be
dedicated to the public regardless of whether such disclosure is
explicitly recited in the claims. No claim element is to be
construed under the provisions of 35 U.S.C. .sctn. 112(f) unless
the element is expressly recited using the phrase "means for" or,
in the case of a method claim, the element is recited using the
phrase "step for."
[0311] The various operations of methods described above may be
performed by any suitable means capable of performing the
corresponding functions. The means may include various hardware
and/or software component(s) and/or module(s), including, but not
limited to a circuit, an application specific integrated circuit
(ASIC), or processor. Generally, where there are operations
illustrated in figures, those operations may have corresponding
counterpart means-plus-function components with similar
numbering.
[0312] The various illustrative logical blocks, modules and
circuits described in connection with the present disclosure may be
implemented or performed with a general purpose processor, a
digital signal processor (DSP), an application specific integrated
circuit (ASIC), a field programmable gate array (FPGA) or other
programmable logic device (PLD), discrete gate or transistor logic,
discrete hardware components, or any combination thereof designed
to perform the functions described herein. A general-purpose
processor may be a microprocessor, but in the alternative, the
processor may be any commercially available processor, controller,
microcontroller, or state machine. A processor may also be
implemented as a combination of computing devices, e.g., a
combination of a DSP and a microprocessor, a plurality of
microprocessors, one or more microprocessors in conjunction with a
DSP core, or any other such configuration.
[0313] If implemented in hardware, an example hardware
configuration may comprise a processing system in a wireless node.
The processing system may be implemented with a bus architecture.
The bus may include any number of interconnecting buses and bridges
depending on the specific application of the processing system and
the overall design constraints. The bus may link together various
circuits including a processor, machine-readable media, and a bus
interface. The bus interface may be used to connect a network
adapter, among other things, to the processing system via the bus.
The network adapter may be used to implement the signal processing
functions of the physical (PHY) layer. In the case of a user
equipment (UE) (see FIG. 1), a user interface (e.g., keypad,
display, mouse, joystick, etc.) may also be connected to the bus.
The bus may also link various other circuits such as timing
sources, peripherals, voltage regulators, power management
circuits, and the like, which are well known in the art, and
therefore, will not be described any further. The processor may be
implemented with one or more general-purpose and/or special-purpose
processors. Examples include microprocessors, microcontrollers, DSP
processors, and other circuitry that can execute software. Those
skilled in the art will recognize how best to implement the
described functionality for the processing system depending on the
particular application and the overall design constraints imposed
on the overall system.
[0314] If implemented in software, the functions may be stored or
transmitted over as one or more instructions or code on a
computer-readable medium. Software shall be construed broadly to
mean instructions, data, or any combination thereof, whether
referred to as software, firmware, middleware, microcode, hardware
description language, or otherwise. Computer-readable media include
both computer storage media and communication media including any
medium that facilitates transfer of a computer program from one
place to another. The processor may be responsible for managing the
bus and general processing, including the execution of software
modules stored on the machine-readable storage media. A
computer-readable storage medium may be coupled to a processor such
that the processor can read information from, and write information
to, the storage medium. In the alternative, the storage medium may
be integral to the processor. By way of example, the
machine-readable media may include a transmission line, a carrier
wave modulated by data, and/or a computer-readable storage medium
with instructions stored thereon separate from the wireless node,
all of which may be accessed by the processor through the bus
interface. Alternatively, or in addition, the machine-readable
media, or any portion thereof, may be integrated into the
processor, such as the case may be with cache and/or general
register files. Examples of machine-readable storage media may
include, by way of example, RAM (Random Access Memory), flash
memory, ROM (Read Only Memory), PROM (Programmable Read-Only
Memory), EPROM (Erasable Programmable Read-Only Memory), EEPROM
(Electrically Erasable Programmable Read-Only Memory), registers,
magnetic disks, optical disks, hard drives, or any other suitable
storage medium, or any combination thereof. The machine-readable
media may be embodied in a computer-program product.
[0315] A software module may comprise a single instruction, or many
instructions, and may be distributed over several different code
segments, among different programs, and across multiple storage
media. The computer-readable media may comprise a number of
software modules. The software modules include instructions that,
when executed by an apparatus such as a processor, cause the
processing system to perform various functions. The software
modules may include a transmission module and a receiving module.
Each software module may reside in a single storage device or be
distributed across multiple storage devices. By way of example, a
software module may be loaded into RAM from a hard drive when a
triggering event occurs. During execution of the software module,
the processor may load some of the instructions into cache to
increase access speed. One or more cache lines may then be loaded
into a general register file for execution by the processor. When
referring to the functionality of a software module below, it will
be understood that such functionality is implemented by the
processor when executing instructions from that software
module.
[0316] Also, any connection is properly termed a computer-readable
medium. For example, if the software is transmitted from a website,
server, or other remote source using a coaxial cable, fiber optic
cable, twisted pair, digital subscriber line (DSL), or wireless
technologies such as infrared (IR), radio, and microwave, then the
coaxial cable, fiber optic cable, twisted pair, DSL, or wireless
technologies such as infrared, radio, and microwave are included in
the definition of medium. Disk and disc, as used herein, include
compact disc (CD), laser disc, optical disc, digital versatile disc
(DVD), floppy disk, and Blu-ray.RTM. disc where disks usually
reproduce data magnetically, while discs reproduce data optically
with lasers. Thus, in some aspects computer-readable media may
comprise non-transitory computer-readable media (e.g., tangible
media). In addition, for other aspects computer-readable media may
comprise transitory computer-readable media (e.g., a signal).
Combinations of the above should also be included within the scope
of computer-readable media.
[0317] Thus, certain aspects may comprise a computer program
product for performing the operations presented herein. For
example, such a computer program product may comprise a
computer-readable medium having instructions stored (and/or
encoded) thereon, the instructions being executable by one or more
processors to perform the operations described herein, for example,
instructions for performing the operations described herein and
illustrated in FIG. 6, FIG. 10A, and/or FIG. 10B.
[0318] Further, it should be appreciated that modules and/or other
appropriate means for performing the methods and techniques
described herein can be downloaded and/or otherwise obtained by a
UE and/or base station as applicable. For example, such a device
can be coupled to a server to facilitate the transfer of means for
performing the methods described herein. Alternatively, various
methods described herein can be provided via storage means (e.g.,
RAM, ROM, a physical storage medium such as a compact disc (CD) or
floppy disk, etc.), such that a UE and/or base station can obtain
the various methods upon coupling or providing the storage means to
the device. Moreover, any other suitable technique for providing
the methods and techniques described herein to a device can be
utilized.
[0319] It is to be understood that the claims are not limited to
the precise configuration and components illustrated above. Various
modifications, changes, and variations may be made in the
arrangement, operation, and details of the methods and apparatus
described above without departing from the scope of the claims.
* * * * *