U.S. patent application number 16/876851 was filed with the patent office on 2020-11-26 for fallback procedures when the path loss or spatial transmit quasi-collocation (qcl) reference from neighboring cells is failing for sounding reference signals (srs) for positioning.
The applicant listed for this patent is QUALCOMM Incorporated. Invention is credited to Sony AKKARAKARAN, Sven FISCHER, Alexandros MANOLAKOS.
Application Number | 20200374806 16/876851 |
Document ID | / |
Family ID | 1000004859866 |
Filed Date | 2020-11-26 |
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United States Patent
Application |
20200374806 |
Kind Code |
A1 |
MANOLAKOS; Alexandros ; et
al. |
November 26, 2020 |
FALLBACK PROCEDURES WHEN THE PATH LOSS OR SPATIAL TRANSMIT
QUASI-COLLOCATION (QCL) REFERENCE FROM NEIGHBORING CELLS IS FAILING
FOR SOUNDING REFERENCE SIGNALS (SRS) FOR POSITIONING
Abstract
Disclosed are techniques for wireless communication. In an
aspect, a UE receives a positioning configuration, the positioning
configuration including at least an identifier of a first downlink
reference signal from a neighboring cell to be used for estimating
a downlink path loss or determining an uplink spatial transmit
beam, determines that a first downlink reference signal received
from the neighboring cell cannot be used for estimating the
downlink path loss or determining the uplink spatial transmit beam,
in response to the determination, estimating the downlink path loss
or determining the uplink spatial transmit beam based on a second
downlink reference signal received from the neighboring cell or a
serving cell, and transmits an uplink reference signal for
positioning based on the estimated downlink path loss, the
determined uplink spatial transmit beam, or a combination
thereof.
Inventors: |
MANOLAKOS; Alexandros; (San
Diego, CA) ; AKKARAKARAN; Sony; (Poway, CA) ;
FISCHER; Sven; (Nuremberg, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM Incorporated |
San Diego |
CA |
US |
|
|
Family ID: |
1000004859866 |
Appl. No.: |
16/876851 |
Filed: |
May 18, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62850503 |
May 20, 2019 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 52/146 20130101;
H04B 17/309 20150115 |
International
Class: |
H04W 52/14 20060101
H04W052/14; H04B 17/309 20060101 H04B017/309 |
Claims
1. A method of wireless communication performed by a user equipment
(UE), comprising: receiving a positioning configuration, the
positioning configuration including at least an identifier of a
first downlink reference signal from a neighboring cell to be used
for estimating a downlink path loss or determining an uplink
spatial transmit beam; determining that the first downlink
reference signal received from the neighboring cell cannot be used
for estimating the downlink path loss or determining the uplink
spatial transmit beam; in response to the determination, estimating
the downlink path loss or determining the uplink spatial transmit
beam based on a second downlink reference signal received from the
neighboring cell or a serving cell; and transmitting an uplink
reference signal for positioning based on the estimated downlink
path loss, the determined uplink spatial transmit beam, or a
combination thereof.
2. The method of claim 1, wherein the second downlink reference
signal is a synchronization signal (SS)/physical broadcast channel
(PBCH) block from the serving cell that the UE uses to obtain a
master information block (MIB) for the serving cell.
3. The method of claim 1, further comprising: setting a transmit
power for the uplink reference signal based on the estimated
downlink path loss.
4. The method of claim 1, further comprising: setting a spatial
beam direction for a transmit beam directed to the neighboring cell
based on the determined uplink spatial transmit beam, the transmit
beam carrying the uplink reference signal.
5. The method of claim 1, further comprising: reporting, to the
serving cell or a location server, that the first downlink
reference signal has failed based on determining that the first
downlink reference signal cannot be used for estimating the
downlink path loss or determining the uplink spatial transmit
beam.
6. The method of claim 1, wherein the UE determines that the first
downlink reference signal cannot be used for estimating the
downlink path loss or determining the uplink spatial transmit beam
based on the signal quality of the first downlink reference signal
being below a threshold.
7. The method of claim 6, wherein the threshold comprises a
reference signal received power (RSRP) threshold configured to the
UE.
8. The method of claim 1, further comprising: transmitting, to the
serving cell via a physical random access channel (PRACH)
procedure, a sequence number indicating that the first downlink
reference signal has failed based on determining that the first
downlink reference signal cannot be used for estimating the
downlink path loss or determining the uplink spatial transmit
beam.
9. The method of claim 1, further comprising: requesting that the
serving cell transmit an alternative and/or secondary downlink
reference signal configured to enable the UE to estimate the
downlink path loss or determine the uplink spatial transmit
beam.
10. The method of claim 1, further comprising: requesting that the
neighboring cell transmit an alternative and/or secondary downlink
reference signal configured to enable the UE to estimate the
downlink path loss or determine the uplink spatial transmit
beam.
11. The method of claim 10, wherein the UE sends the request to the
serving cell.
12. The method of claim 1, further comprising: initiating a partial
beam failure recovery procedure to report that a subset of downlink
reference signals from the neighboring cell have failed.
13. The method of claim 12, wherein the subset of downlink
reference signals comprises more than one downlink reference signal
from the neighboring cell.
14. The method of claim 1, wherein the UE receives a plurality of
downlink reference signals from the neighboring cell, and wherein
the first and second downlink reference signals are two of the
plurality of downlink reference signals.
15. The method of claim 14, wherein: the first downlink reference
signal is configured for downlink path loss estimation for a first
carrier bandwidth part used to communicate with the neighboring
cell, and the second downlink reference signal is configured for
downlink path loss estimation for a second carrier bandwidth part
used to communicate with the neighboring cell.
16. The method of claim 1, wherein: the first downlink reference
signal is the only downlink reference signal the UE receives from
the neighboring cell, and the second downlink reference signal is a
downlink reference signal received from the serving cell.
17. The method of claim 1, wherein the second downlink reference
signal is a default downlink reference signal used for both the
estimated downlink path loss and the determined uplink spatial
transmit beam.
18. The method of claim 17, wherein the second downlink reference
signal is received on a transmit beam from the serving cell.
19. The method of claim 1, wherein the UE transmits uplink
reference signals at a maximum transmit power after determining
that the first downlink reference signal cannot be used for
estimating the downlink path loss or determining the uplink spatial
transmit beam and before estimating the downlink path loss based on
the second downlink reference signal.
20. The method of claim 1, wherein the second downlink reference
signal is a secondary downlink reference signal from the serving
cell configured to assist with the uplink spatial transmit beam
determination.
21. The method of claim 1, wherein the second downlink reference
signal is a synchronization signal (SS)/physical broadcast channel
(PBCH) block from the serving cell that the UE uses to obtain a
master information block (MIB) for the serving cell.
22. A method of wireless communication performed by a location
server, comprising: configuring a user equipment (UE) to receive at
least a first downlink reference signal from a neighboring cell to
be used to estimate a downlink path loss or determine an uplink
spatial transmit beam; receiving, from the UE, a report indicating
a signal quality of the first downlink reference signal; and based
on the signal quality of the first downlink reference signal being
below a threshold, configuring the UE to receive at least a second
downlink reference signal from the neighboring cell or a serving
cell to be used to estimate the downlink path loss or determine the
uplink spatial transmit beam.
23. The method of claim 22, wherein the signal quality of the first
downlink reference signal being below the threshold indicates that
the first downlink reference signal cannot be used for the downlink
path loss estimation or the uplink spatial transmit beam
determination.
24. The method of claim 22, wherein the location server
periodically receives the report indicating the signal quality of
the first downlink reference signal.
25. A method of wireless communication performed by a user
equipment (UE), comprising: receiving, from a network node, a
configuration to use at least a first downlink reference signal
from a neighboring cell to estimate a downlink path loss or
determine an uplink spatial transmit beam; sending, to the network
node, a report indicating a signal quality of the first downlink
reference signal; and based on the signal quality of the first
downlink reference signal being below a threshold, receiving, from
the network node, a configuration to use at least a second downlink
reference signal from the neighboring cell or a serving cell to
estimate the downlink path loss or determine the uplink spatial
transmit beam.
26. The method of claim 25, wherein the network node comprises a
serving base station of the UE.
27. The method of claim 25, wherein the network node comprises a
location server.
28. The method of claim 25, wherein the signal quality of the first
downlink reference signal being below the threshold indicates that
the first downlink reference signal cannot be used for the downlink
path loss estimation or the uplink spatial transmit beam
determination.
29. The method of claim 25, wherein the UE periodically sends the
report indicating the signal quality of the first downlink
reference signal.
30. A user equipment (UE), comprising: a memory; at least one
transceiver; and at least one processor communicatively coupled to
the memory and the at least one transceiver, the at least one
processor configured to: receive, via the at least one transceiver,
a positioning configuration, the positioning configuration
including at least an identifier of a first downlink reference
signal from a neighboring cell to be used for estimating a downlink
path loss or determining an uplink spatial transmit beam; determine
that the first downlink reference signal received from the
neighboring cell cannot be used to estimate the downlink path loss
or determine the uplink spatial transmit beam; estimate, in
response to the determination, the downlink path loss or
determining the uplink spatial transmit beam based on a second
downlink reference signal received from the neighboring cell or a
serving cell; and cause the at least one transceiver to transmit an
uplink reference signal for positioning based on the estimated
downlink path loss, the determined uplink spatial transmit beam, or
a combination thereof.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application for patent claims the benefit of
U.S. Provisional Application No. 62/850,503, entitled "REPORTING OF
INFORMATION RELATED TO SOUNDING REFERENCE SIGNALS (SRS) TIMING
ADJUSTMENTS," filed May 20, 2019, assigned to the assignee hereof,
and expressly incorporated herein by reference in its entirety.
BACKGROUND OF THE DISCLOSURE
1. Field of the Disclosure
[0002] Aspects of the disclosure relate generally to
telecommunications, and more particularly to the reporting of
information related to uplink reference signal timing adjustments
for enhanced uplink reference signal processing.
2. Description of the Related Art
[0003] Wireless communication systems have developed through
various generations, including a first-generation analog wireless
phone service (1G), a second-generation (2G) digital wireless phone
service (including interim 2.5G and 2.75G networks), a
third-generation (3G) high speed data, Internet-capable wireless
service and a fourth-generation (4G) service (e.g., Long Term
Evolution (LTE) or WiMax). There are presently many different types
of wireless communication systems in use, including cellular and
personal communications service (PCS) systems. Examples of known
cellular systems include the cellular analog advanced mobile phone
system (AMPS), and digital cellular systems based on code division
multiple access (CDMA), frequency division multiple access (FDMA),
time division multiple access (TDMA), the Global System for Mobile
access (GSM) variation of TDMA, etc.
[0004] A fifth generation (5G) wireless standard, referred to as
New Radio (NR), calls for higher data transfer speeds, greater
numbers of connections, and better coverage, among other
improvements. The 5G standard, according to the Next Generation
Mobile Networks Alliance, is designed to provide data rates of
several tens of megabits per second to each of tens of thousands of
users, with 1 gigabit per second to tens of workers on an office
floor. Several hundreds of thousands of simultaneous connections
should be supported in order to support large sensor deployments.
Consequently, the spectral efficiency of 5G mobile communications
should be significantly enhanced compared to the current 4G
standard. Furthermore, signaling efficiencies should be enhanced
and latency should be substantially reduced compared to current
standards.
[0005] To support position estimations in terrestrial wireless
networks, a mobile device can be configured to measure and report
the observed time difference of arrival (OTDOA) or reference signal
timing difference (RSTD) between reference signals received from
two or more network nodes (e.g., different base stations or
different transmission points (e.g., antennas) belonging to the
same base station).
SUMMARY
[0006] The following presents a simplified summary relating to one
or more aspects disclosed herein. Thus, the following summary
should not be considered an extensive overview relating to all
contemplated aspects, nor should the following summary be
considered to identify key or critical elements relating to all
contemplated aspects or to delineate the scope associated with any
particular aspect. Accordingly, the following summary has the sole
purpose to present certain concepts relating to one or more aspects
relating to the mechanisms disclosed herein in a simplified form to
precede the detailed description presented below.
[0007] In an aspect, a method of wireless communication performed
by a user equipment (UE) includes receiving a positioning
configuration, the positioning configuration including at least an
identifier of a first downlink reference signal from a neighboring
cell to be used for estimating a downlink path loss or determining
an uplink spatial transmit beam, determining that the first
downlink reference signal received from the neighboring cell cannot
be used for estimating the downlink path loss or determining the
uplink spatial transmit beam, in response to the determination,
estimating the downlink path loss or determining the uplink spatial
transmit beam based on a second downlink reference signal received
from the neighboring cell or a serving cell, and transmitting an
uplink reference signal for positioning based on the estimated
downlink path loss, the determined uplink spatial transmit beam, or
a combination thereof.
[0008] In an aspect, a method of wireless communication performed
by a location server includes configuring a UE to receive at least
a first downlink reference signal from a neighboring cell to be
used to estimate a downlink path loss or determine an uplink
spatial transmit beam, receiving, from the UE, a report indicating
a signal quality of the first downlink reference signal, and based
on the signal quality of the first downlink reference signal being
below a threshold, configuring the UE to receive at least a second
downlink reference signal from the neighboring cell or a serving
cell to be used to estimate the downlink path loss or determine the
uplink spatial transmit beam.
[0009] In an aspect, a method of wireless communication performed
by a UE includes receiving, from a network node, a configuration to
use at least a first downlink reference signal from a neighboring
cell to estimate a downlink path loss or determine an uplink
spatial transmit beam, sending, to the network node, a report
indicating a signal quality of the first downlink reference signal,
and based on the signal quality of the first downlink reference
signal being below a threshold, receiving, from the network node, a
configuration to use at least a second downlink reference signal
from the neighboring cell or a serving cell to estimate the
downlink path loss or determine the uplink spatial transmit
beam.
[0010] In an aspect, a UE includes a memory, at least one
transceiver, and at least one processor communicatively coupled to
the memory and the at least one transceiver, the at least one
processor configured to: receive, via the at least one transceiver,
a positioning configuration, the positioning configuration
including at least an identifier of a first downlink reference
signal from a neighboring cell to be used for estimating a downlink
path loss or determining an uplink spatial transmit beam, determine
that the first downlink reference signal received from the
neighboring cell cannot be used to estimate the downlink path loss
or determine the uplink spatial transmit beam, in response to the
determination, estimate the downlink path loss or determining the
uplink spatial transmit beam based on a second downlink reference
signal received from the neighboring cell or a serving cell, and
cause the at least one transceiver to transmit an uplink reference
signal for positioning based on the estimated downlink path loss,
the determined uplink spatial transmit beam, or a combination
thereof.
[0011] In an aspect, a location server includes a memory, at least
one network interface, and at least one processor communicatively
coupled to the memory and the at least one network interface, the
at least one processor configured to: configure a UE to receive at
least a first downlink reference signal from a neighboring cell to
be used to estimate a downlink path loss or determine an uplink
spatial transmit beam, receive, from the UE, a report indicating a
signal quality of the first downlink reference signal, and
configure the UE, based on the signal quality of the first downlink
reference signal being below a threshold, to receive at least a
second downlink reference signal from the neighboring cell or a
serving cell to be used to estimate the downlink path loss or
determine the uplink spatial transmit beam.
[0012] In an aspect, a UE includes a memory, at least one
transceiver, and at least one processor communicatively coupled to
the memory and the at least one transceiver, the at least one
processor configured to: receive, from a network node, a
configuration to use at least a first downlink reference signal
from a neighboring cell to estimate a downlink path loss or
determine an uplink spatial transmit beam, send, to the network
node, a report indicating a signal quality of the first downlink
reference signal, and receive, from the network node, based on the
signal quality of the first downlink reference signal being below a
threshold, a configuration to use at least a second downlink
reference signal from the neighboring cell or a serving cell to
estimate the downlink path loss or determine the uplink spatial
transmit beam.
[0013] In an aspect, a UE includes means for receiving a
positioning configuration, the positioning configuration including
at least an identifier of a first downlink reference signal from a
neighboring cell to be used for estimating a downlink path loss or
determining an uplink spatial transmit beam, means for determining
that the first downlink reference signal received from the
neighboring cell cannot be used to estimate the downlink path loss
or determine the uplink spatial transmit beam, in response to the
determination, means for estimating the downlink path loss or
determining the uplink spatial transmit beam based on a second
downlink reference signal received from the neighboring cell or a
serving cell, and means for transmitting an uplink reference signal
for positioning based on the estimated downlink path loss, the
determined uplink spatial transmit beam, or a combination
thereof.
[0014] In an aspect, a location server includes means for
configuring a UE to receive at least a first downlink reference
signal from a neighboring cell to be used to estimate a downlink
path loss or determine an uplink spatial transmit beam, means for
receiving, from the UE, a report indicating a signal quality of the
first downlink reference signal, and based on the signal quality of
the first downlink reference signal being below a threshold, means
for configuring the UE to receive at least a second downlink
reference signal from the neighboring cell or a serving cell to be
used to estimate the downlink path loss or determine the uplink
spatial transmit beam.
[0015] In an aspect, a UE includes means for receiving, from a
network node, a configuration to use at least a first downlink
reference signal from a neighboring cell to estimate a downlink
path loss or determine an uplink spatial transmit beam, means for
sending, to the network node, a report indicating a signal quality
of the first downlink reference signal, and means for receiving,
from the network node, based on the signal quality of the first
downlink reference signal being below a threshold, a configuration
to use at least a second downlink reference signal from the
neighboring cell or a serving cell to estimate the downlink path
loss or determine the uplink spatial transmit beam.
[0016] In an aspect, a non-transitory computer-readable medium
storing computer-executable instructions includes
computer-executable instructions comprising at least one
instruction instructing a UE to receive a positioning
configuration, the positioning configuration including at least an
identifier of a first downlink reference signal from a neighboring
cell to be used for estimating a downlink path loss or determining
an uplink spatial transmit beam, at least one instruction
instructing the UE to determine that the first downlink reference
signal received from the neighboring cell cannot be used to
estimate the downlink path loss or determine the uplink spatial
transmit beam, at least one instruction instructing the UE to
estimate, in response to the determination, the downlink path loss
or determining the uplink spatial transmit beam based on a second
downlink reference signal received from the neighboring cell or a
serving cell, and at least one instruction instructing the UE to
transmit an uplink reference signal for positioning based on the
estimated downlink path loss, the determined uplink spatial
transmit beam, or a combination thereof.
[0017] In an aspect, a non-transitory computer-readable medium
storing computer-executable instructions includes
computer-executable instructions comprising at least one
instruction instructing a location server to configure a UE to
receive at least a first downlink reference signal from a
neighboring cell to be used to estimate a downlink path loss or
determine an uplink spatial transmit beam, at least one instruction
instructing the location server to receive, from the UE, a report
indicating a signal quality of the first downlink reference signal,
and at least one instruction instructing the location server to
configure, based on the signal quality of the first downlink
reference signal being below a threshold, the UE to receive at
least a second downlink reference signal from the neighboring cell
or a serving cell to be used to estimate the downlink path loss or
determine the uplink spatial transmit beam.
[0018] In an aspect, a non-transitory computer-readable medium
storing computer-executable instructions includes
computer-executable instructions comprising at least one
instruction instructing a UE to receive, from a network node, a
configuration to use at least a first downlink reference signal
from a neighboring cell to estimate a downlink path loss or
determine an uplink spatial transmit beam, at least one instruction
instructing the UE to send, to the network node, a report
indicating a signal quality of the first downlink reference signal,
and at least one instruction instructing the UE to receive, from
the network node, based on the signal quality of the first downlink
reference signal being below a threshold, a configuration to use at
least a second downlink reference signal from the neighboring cell
or a serving cell to estimate the downlink path loss or determine
the uplink spatial transmit beam.
[0019] Other objects and advantages associated with the aspects
disclosed herein will be apparent to those skilled in the art based
on the accompanying drawings and detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The accompanying drawings are presented to aid in the
description of various aspects of the disclosure and are provided
solely for illustration of the aspects and not limitation
thereof.
[0021] FIG. 1 illustrates an exemplary wireless communications
system, according to various aspects of the disclosure.
[0022] FIGS. 2A and 2B illustrate exemplary wireless network
structures, according to various aspects of the disclosure.
[0023] FIGS. 3A to 3C are simplified block diagrams of several
exemplary aspects of components that may be employed in wireless
communication nodes and configured to support communication,
according to various aspects of the disclosure.
[0024] FIGS. 4A to 4D are diagrams illustrating exemplary frame
structures and channels within the frame structures, according to
aspects of the disclosure.
[0025] FIGS. 5A and 5B illustrate exemplary random access
procedures, according to aspects of the disclosure.
[0026] FIG. 6 is a diagram of an exemplary random access-based
SpCell beam failure recovery procedure, according to aspects of the
disclosure.
[0027] FIG. 7 is a diagram illustrating an exemplary technique for
determining a position of a mobile device using information
obtained from a plurality of base stations.
[0028] FIGS. 8-10 illustrate exemplary methods of wireless
communication, according to aspects of the disclosure.
DETAILED DESCRIPTION
[0029] Aspects of the disclosure are provided in the following
description and related drawings directed to various examples
provided for illustration purposes. Alternate aspects may be
devised without departing from the scope of the disclosure.
Additionally, well-known elements of the disclosure will not be
described in detail or will be omitted so as not to obscure the
relevant details of the disclosure.
[0030] The words "exemplary" and/or "example" are used herein to
mean "serving as an example, instance, or illustration." Any aspect
described herein as "exemplary" and/or "example" is not necessarily
to be construed as preferred or advantageous over other aspects.
Likewise, the term "aspects of the disclosure" does not require
that all aspects of the disclosure include the discussed feature,
advantage or mode of operation.
[0031] Those of skill in the art will appreciate that the
information and signals described below may be represented using
any of a variety of different technologies and techniques. For
example, data, instructions, commands, information, signals, bits,
symbols, and chips that may be referenced throughout the
description below may be represented by voltages, currents,
electromagnetic waves, magnetic fields or particles, optical fields
or particles, or any combination thereof, depending in part on the
particular application, in part on the desired design, in part on
the corresponding technology, etc.
[0032] Further, many aspects are described in terms of sequences of
actions to be performed by, for example, elements of a computing
device. It will be recognized that various actions described herein
can be performed by specific circuits (e.g., application specific
integrated circuits (ASICs)), by program instructions being
executed by one or more processors, or by a combination of both.
Additionally, the sequence(s) of actions described herein can be
considered to be embodied entirely within any form of
non-transitory computer-readable storage medium having stored
therein a corresponding set of computer instructions that, upon
execution, would cause or instruct an associated processor of a
device to perform the functionality described herein. Thus, the
various aspects of the disclosure may be embodied in a number of
different forms, all of which have been contemplated to be within
the scope of the claimed subject matter. In addition, for each of
the aspects described herein, the corresponding form of any such
aspects may be described herein as, for example, "logic configured
to" perform the described action.
[0033] As used herein, the terms "user equipment" (UE) and "base
station" are not intended to be specific or otherwise limited to
any particular radio access technology (RAT), unless otherwise
noted. In general, a UE may be any wireless communication device
(e.g., a mobile phone, router, tablet computer, laptop computer,
tracking device, wearable (e.g., smartwatch, glasses, augmented
reality (AR)/virtual reality (VR) headset, etc.), vehicle (e.g.,
automobile, motorcycle, bicycle, etc.), Internet of Things (IoT)
device, etc.) used by a user to communicate over a wireless
communications network. A UE may be mobile or may (e.g., at certain
times) be stationary, and may communicate with a radio access
network (RAN). As used herein, the term "UE" may be referred to
interchangeably as an "access terminal" or "AT," a "client device,"
a "wireless device," a "subscriber device," a "subscriber
terminal," a "subscriber station," a "user terminal" or UT, a
"mobile terminal," a "mobile station," or variations thereof.
Generally, UEs can communicate with a core network via a RAN, and
through the core network the UEs can be connected with external
networks such as the Internet and with other UEs. Of course, other
mechanisms of connecting to the core network and/or the Internet
are also possible for the UEs, such as over wired access networks,
wireless local area network (WLAN) networks (e.g., based on IEEE
802.11, etc.) and so on.
[0034] A base station may operate according to one of several RATs
in communication with UEs depending on the network in which it is
deployed, and may be alternatively referred to as an access point
(AP), a network node, a NodeB, an evolved NodeB (eNB), a New Radio
(NR) Node B (also referred to as a gNB or gNodeB), etc. In
addition, in some systems a base station may provide purely edge
node signaling functions while in other systems it may provide
additional control and/or network management functions. A
communication link through which UEs can send signals to a base
station is called an uplink (UL) channel (e.g., a reverse traffic
channel, a reverse control channel, an access channel, etc.). A
communication link through which the base station can send signals
to UEs is called a downlink (DL) or forward link channel (e.g., a
paging channel, a control channel, a broadcast channel, a forward
traffic channel, etc.). As used herein the term traffic channel
(TCH) can refer to either an uplink/reverse or downlink/forward
traffic channel.
[0035] The term "base station" may refer to a single physical
transmission-reception point (TRP) or to multiple physical TRPs
that may or may not be co-located. For example, where the term
"base station" refers to a single physical TRP, the physical TRP
may be an antenna of the base station corresponding to a cell of
the base station. Where the term "base station" refers to multiple
co-located physical TRPs, the physical TRPs may be an array of
antennas (e.g., as in a multiple-input multiple-output (MIMO)
system or where the base station employs beamforming) of the base
station. Where the term "base station" refers to multiple
non-co-located physical TRPs, the physical TRPs may be a
distributed antenna system (DAS) (a network of spatially separated
antennas connected to a common source via a transport medium) or a
remote radio head (RRH) (a remote base station connected to a
serving base station). Alternatively, the non-co-located physical
TRPs may be the serving base station receiving the measurement
report from the UE and a neighbor base station whose reference
signals the UE is measuring. Because a TRP is the point from which
a base station transmits and receives wireless signals, as used
herein, references to transmission from or reception at a base
station are to be understood as referring to a particular TRP of
the base station.
[0036] A radio frequency (RF) signal comprises an electromagnetic
wave of a given frequency that transports information through the
space between a transmitter and a receiver. As used herein, a
transmitter may transmit a single RF signal or multiple RF signals
to a receiver. However, the receiver may receive multiple RF
signals corresponding to each transmitted RF signal due to the
propagation characteristics of RF signals through multipath
channels. The same transmitted RF signal on different paths between
the transmitter and receiver may be referred to as a "multipath" RF
signal.
[0037] According to various aspects, FIG. 1 illustrates an
exemplary wireless communications system 100. The wireless
communications system 100 (which may also be referred to as a
wireless wide area network (WWAN)) may include various base
stations 102 (labeled "BS") and various UEs 104. The base stations
102 may include macro cell base stations (high power cellular base
stations) and/or small cell base stations (low power cellular base
stations). In an aspect, the macro cell base stations 102 may
include eNBs where the wireless communications system 100
corresponds to an LTE network, or gNBs where the wireless
communications system 100 corresponds to an NR network, or a
combination of both, and the small cell base stations 102' may
include femtocells, picocells, microcells, etc.
[0038] The base stations 102 may collectively form a RAN and
interface with a core network 170 (e.g., an evolved packet core
(EPC) or next generation core (NGC)) through backhaul links 122,
and through the core network 170 to one or more location servers
172. In addition to other functions, the base stations 102 may
perform functions that relate to one or more of transferring user
data, radio channel ciphering and deciphering, integrity
protection, header compression, mobility control functions (e.g.,
handover, dual connectivity), inter-cell interference coordination,
connection setup and release, load balancing, distribution for
non-access stratum (NAS) messages, NAS node selection,
synchronization, RAN sharing, multimedia broadcast multicast
service (MBMS), subscriber and equipment trace, RAN information
management (RIM), paging, positioning, and delivery of warning
messages. The base stations 102 may communicate with each other
directly or indirectly (e.g., through the EPC/NGC) over backhaul
links 134, which may be wired or wireless.
[0039] The base stations 102 may wirelessly communicate with the
UEs 104. Each of the base stations 102 may provide communication
coverage for a respective geographic coverage area 110. In an
aspect, one or more cells may be supported by a base station 102 in
each geographic coverage area 110. A "cell" is a logical
communication entity used for communication with a base station
(e.g., over some frequency resource, referred to as a carrier
frequency, component carrier, carrier, band, or the like), and may
be associated with an identifier (e.g., a physical cell identifier
(PCI), a virtual cell identifier (VCI)) for distinguishing cells
operating via the same or a different carrier frequency. In some
cases, different cells may be configured according to different
protocol types (e.g., machine-type communication (MTC), narrowband
IoT (NB-IoT), enhanced mobile broadband (eMBB), or others) that may
provide access for different types of UEs. Because a cell is
supported by a specific base station, the term "cell" may refer to
either or both the logical communication entity and the base
station that supports it, depending on the context. In some cases,
the term "cell" may also refer to a geographic coverage area of a
base station (e.g., a sector), insofar as a carrier frequency can
be detected and used for communication within some portion of
geographic coverage areas 110.
[0040] While neighboring macro cell base station 102 geographic
coverage areas 110 may partially overlap (e.g., in a handover
region), some of the geographic coverage areas 110 may be
substantially overlapped by a larger geographic coverage area 110.
For example, a small cell base station 102' (labeled "SC" for
"small cell") may have a geographic coverage area 110' that
substantially overlaps with the geographic coverage area 110 of one
or more macro cell base stations 102. A network that includes both
small cell and macro cell base stations may be known as a
heterogeneous network. A heterogeneous network may also include
home eNBs (HeNBs), which may provide service to a restricted group
known as a closed subscriber group (CSG).
[0041] The communication links 120 between the base stations 102
and the UEs 104 may include uplink (also referred to as reverse
link) transmissions from a UE 104 to a base station 102 and/or
downlink (DL) (also referred to as forward link) transmissions from
a base station 102 to a UE 104. The communication links 120 may use
MIMO antenna technology, including spatial multiplexing,
beamforming, and/or transmit diversity. The communication links 120
may be through one or more carrier frequencies. Allocation of
carriers may be asymmetric with respect to downlink and uplink
(e.g., more or less carriers may be allocated for downlink than for
UL).
[0042] The wireless communications system 100 may further include a
wireless local area network (WLAN) access point (AP) 150 in
communication with one or more WLAN stations (STAs) 152 via
communication links 154 in an unlicensed frequency spectrum (e.g.,
5 GHz). When communicating in an unlicensed frequency spectrum, the
WLAN STAs 152 and/or the WLAN AP 150 may perform a clear channel
assessment (CCA) or listen before talk (LBT) procedure prior to
communicating in order to determine whether the channel is
available.
[0043] The small cell base station 102' may operate in a licensed
and/or an unlicensed frequency spectrum. When operating in an
unlicensed frequency spectrum, the small cell base station 102' may
employ LTE or NR technology and use the same 5 GHz unlicensed
frequency spectrum as used by the WLAN AP 150. The small cell base
station 102', employing LTE/5G in an unlicensed frequency spectrum,
may boost coverage to and/or increase capacity of the access
network. NR in unlicensed spectrum may be referred to as NR-U. LTE
in an unlicensed spectrum may be referred to as LTE-U, licensed
assisted access (LAA), or MulteFire.
[0044] The wireless communications system 100 may further include a
millimeter wave (mmW) base station 180 that may operate in mmW
frequencies and/or near mmW frequencies in communication with a UE
182. Extremely high frequency (EHF) is part of the RF in the
electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and
a wavelength between 1 millimeter and 10 millimeters. Radio waves
in this band may be referred to as a millimeter wave. Near mmW may
extend down to a frequency of 3 GHz with a wavelength of 100
millimeters. The super high frequency (SHF) band extends between 3
GHz and 30 GHz, also referred to as centimeter wave. Communications
using the mmW/near mmW radio frequency band have a high path loss
and a relatively short range. The mmW base station 180 and the UE
182 may utilize beamforming (transmit and/or receive) over an mmW
communication link 184 to compensate for the extremely high path
loss and short range. Further, it will be appreciated that in
alternative configurations, one or more base stations 102 may also
transmit using mmW or near mmW and beamforming. Accordingly, it
will be appreciated that the foregoing illustrations are merely
examples and should not be construed to limit the various aspects
disclosed herein.
[0045] Transmit beamforming is a technique for focusing an RF
signal in a specific direction. Traditionally, when a network node
(e.g., a base station) broadcasts an RF signal, it broadcasts the
signal in all directions (omni-directionally). With transmit
beamforming, the network node determines where a given target
device (e.g., a UE) is located (relative to the transmitting
network node) and projects a stronger downlink RF signal in that
specific direction, thereby providing a faster (in terms of data
rate) and stronger RF signal for the receiving device(s). To change
the directionality of the RF signal when transmitting, a network
node can control the phase and relative amplitude of the RF signal
at each of the one or more transmitters that are broadcasting the
RF signal. For example, a network node may use an array of antennas
(referred to as a "phased array" or an "antenna array") that
creates a beam of RF waves that can be "steered" to point in
different directions, without actually moving the antennas.
Specifically, the RF current from the transmitter is fed to the
individual antennas with the correct phase relationship so that the
radio waves from the separate antennas add together to increase the
radiation in a desired direction, while cancelling to suppress
radiation in undesired directions.
[0046] Transmit beams may be quasi-collocated, meaning that they
appear to the receiver (e.g., a UE) as having the same parameters,
regardless of whether or not the transmitting antennas of the
network node themselves are physically collocated. In NR, there are
four types of quasi-collocation (QCL) relations. Specifically, a
QCL relation of a given type means that certain parameters about a
second reference signal on a second beam can be derived from
information about a source reference signal on a source beam. Thus,
if the source reference signal is QCL Type A, the receiver can use
the source reference signal to estimate the Doppler shift, Doppler
spread, average delay, and delay spread of a second reference
signal transmitted on the same channel. If the source reference
signal is QCL Type B, the receiver can use the source reference
signal to estimate the Doppler shift and Doppler spread of a second
reference signal transmitted on the same channel. If the source
reference signal is QCL Type C, the receiver can use the source
reference signal to estimate the Doppler shift and average delay of
a second reference signal transmitted on the same channel. If the
source reference signal is QCL Type D, the receiver can use the
source reference signal to estimate the spatial receive parameter
of a second reference signal transmitted on the same channel.
[0047] In receive beamforming, the receiver uses a receive beam to
amplify RF signals detected on a given channel. For example, the
receiver can increase the gain setting and/or adjust the phase
setting of an array of antennas in a particular direction to
amplify (e.g., to increase the gain level of) the RF signals
received from that direction. Thus, when a receiver is said to
beamform in a certain direction, it means the beam gain in that
direction is high relative to the beam gain along other directions,
or the beam gain in that direction is the highest compared to the
beam gain in that direction of all other receive beams available to
the receiver. This results in a stronger received signal strength
(e.g., reference signal received power (RSRP), reference signal
received quality (RSRQ), signal-to-interference-plus-noise ratio
(SINR), etc.) of the RF signals received from that direction.
[0048] Transmit and receive beams may be spatially related. A
spatial relation means that parameters for a second beam (e.g., a
transmit or receive beam) for a second reference signal can be
derived from information about a first beam (e.g., a receive beam
or a transmit beam) for a first reference signal. For example, a UE
may use a particular receive beam to receive a reference downlink
reference signal (e.g., synchronization signal block (SSB)) from a
base station. The UE can then form a transmit beam for sending an
uplink reference signal (e.g., sounding reference signal (SRS)) to
that base station based on the parameters of the receive beam.
[0049] Note that a "downlink" beam may be either a transmit beam or
a receive beam, depending on the entity forming it. For example, if
a base station is forming the downlink beam to transmit a reference
signal to a UE, the downlink beam is a transmit beam. If the UE is
forming the downlink beam, however, it is a receive beam to receive
the downlink reference signal. Similarly, an "uplink" beam may be
either a transmit beam or a receive beam, depending on the entity
forming it. For example, if a base station is forming the uplink
beam, it is an uplink receive beam, and if a UE is forming the
uplink beam, it is an uplink transmit beam.
[0050] In 5G, the frequency spectrum in which wireless nodes (e.g.,
base stations 102/180, UEs 104/182) operate is divided into
multiple frequency ranges, FR1 (from 450 to 6000 MHz), FR2 (from
24250 to 52600 MHz), FR3 (above 52600 MHz), and FR4 (between FR1
and FR2). In a multi-carrier system, such as 5G, one of the carrier
frequencies is referred to as the "primary carrier" or "anchor
carrier" or "primary serving cell" or "PCell," and the remaining
carrier frequencies are referred to as "secondary carriers" or
"secondary serving cells" or "SCells." In carrier aggregation, the
anchor carrier is the carrier operating on the primary frequency
(e.g., FR1) utilized by a UE 104/182 and the cell in which the UE
104/182 either performs the initial radio resource control (RRC)
connection establishment procedure or initiates the RRC connection
re-establishment procedure. The primary carrier carries all common
and UE-specific control channels, and may be a carrier in a
licensed frequency (however, this is not always the case). A
secondary carrier is a carrier operating on a second frequency
(e.g., FR2) that may be configured once the RRC connection is
established between the UE 104 and the anchor carrier and that may
be used to provide additional radio resources. In some cases, the
secondary carrier may be a carrier in an unlicensed frequency. The
secondary carrier may contain only necessary signaling information
and signals, for example, those that are UE-specific may not be
present in the secondary carrier, since both primary uplink and
downlink carriers are typically UE-specific. This means that
different UEs 104/182 in a cell may have different downlink primary
carriers. The same is true for the uplink primary carriers. The
network is able to change the primary carrier of any UE 104/182 at
any time. This is done, for example, to balance the load on
different carriers. Because a "serving cell" (whether a PCell or an
SCell) corresponds to a carrier frequency/component carrier over
which some base station is communicating, the term "cell," "serving
cell," "component carrier," "carrier frequency," and the like can
be used interchangeably.
[0051] For example, still referring to FIG. 1, one of the
frequencies utilized by the macro cell base stations 102 may be an
anchor carrier (or "PCell") and other frequencies utilized by the
macro cell base stations 102 and/or the mmW base station 180 may be
secondary carriers ("SCells"). The simultaneous transmission and/or
reception of multiple carriers enables the UE 104/182 to
significantly increase its data transmission and/or reception
rates. For example, two 20 MHz aggregated carriers in a
multi-carrier system would theoretically lead to a two-fold
increase in data rate (i.e., 40 MHz), compared to that attained by
a single 20 MHz carrier.
[0052] The wireless communications system 100 may further include
one or more UEs, such as UE 190, that connects indirectly to one or
more communication networks via one or more device-to-device (D2D)
peer-to-peer (P2P) links. In the example of FIG. 1, UE 190 has a
D2D P2P link 192 with one of the UEs 104 connected to one of the
base stations 102 (e.g., through which UE 190 may indirectly obtain
cellular connectivity) and a D2D P2P link 194 with WLAN STA 152
connected to the WLAN AP 150 (through which UE 190 may indirectly
obtain WLAN-based Internet connectivity). In an example, the D2D
P2P links 192 and 194 may be supported with any well-known D2D RAT,
such as LTE Direct (LTE-D), WiFi Direct (WiFi-D), Bluetooth.RTM.,
and so on.
[0053] The wireless communications system 100 may further include a
UE 164 that may communicate with a macro cell base station 102 over
a communication link 120 and/or the mmW base station 180 over a mmW
communication link 184. For example, the macro cell base station
102 may support a PCell and one or more SCells for the UE 164 and
the mmW base station 180 may support one or more SCells for the UE
164.
[0054] According to various aspects, FIG. 2A illustrates an
exemplary wireless network structure 200. For example, an NGC 210
(also referred to as a "5GC") can be viewed functionally as control
plane functions (C-plane) 214 (e.g., UE registration,
authentication, network access, gateway selection, etc.) and user
plane functions (U-plane) 212 (e.g., UE gateway function, access to
data networks, IP routing, etc.), which operate cooperatively to
form the core network. User plane interface (NG-U) 213 and control
plane interface (NG-C) 215 connect the gNB 222 to the NGC 210 and
specifically to the user plane functions 212 and control plane
functions 214, respectively. In an additional configuration, an eNB
224 may also be connected to the NGC 210 via NG-C 215 to the
control plane functions 214 and NG-U 213 to user plane functions
212. Further, eNB 224 may directly communicate with gNB 222 via a
backhaul connection 223. In some configurations, the New RAN 220
may only have one or more gNBs 222, while other configurations
include one or more of both eNBs 224 and gNBs 222. Either gNB 222
or eNB 224 may communicate with UEs 204 (e.g., any of the UEs
depicted in FIG. 1). Another optional aspect may include location
server 230, which may be in communication with the NGC 210 to
provide location assistance for UEs 204. The location server 230
can be implemented as a plurality of separate servers (e.g.,
physically separate servers, different software modules on a single
server, different software modules spread across multiple physical
servers, etc.), or alternately may each correspond to a single
server. The location server 230 can be configured to support one or
more location services for UEs 204 that can connect to the location
server 230 via the core network, NGC 210, and/or via the Internet
(not illustrated). Further, the location server 230 may be
integrated into a component of the core network, or alternatively
may be external to the core network.
[0055] According to various aspects, FIG. 2B illustrates another
exemplary wireless network structure 250. For example, an NGC 260
(also referred to as a "5GC") can be viewed functionally as control
plane functions, provided by an access and mobility management
function (AMF)/user plane function (UPF) 264, and user plane
functions, provided by a session management function (SMF) 262,
which operate cooperatively to form the core network (i.e., NGC
260). User plane interface 263 and control plane interface 265
connect the eNB 224 to the NGC 260 and specifically to SMF 262 and
AMF/UPF 264, respectively. In an additional configuration, a gNB
222 may also be connected to the NGC 260 via control plane
interface 265 to AMF/UPF 264 and user plane interface 263 to SMF
262. Further, eNB 224 may directly communicate with gNB 222 via the
backhaul connection 223, with or without gNB direct connectivity to
the NGC 260. In some configurations, the New RAN 220 may only have
one or more gNBs 222, while other configurations include one or
more of both eNBs 224 and gNBs 222. Either gNB 222 or eNB 224 may
communicate with UEs 204 (e.g., any of the UEs depicted in FIG. 1).
The base stations of the New RAN 220 communicate with the AMF-side
of the AMF/UPF 264 over the N2 interface and the UPF-side of the
AMF/UPF 264 over the N3 interface.
[0056] The functions of the AMF include registration management,
connection management, reachability management, mobility
management, lawful interception, transport for session management
(SM) messages between the UE 204 and the SMF 262, transparent proxy
services for routing SM messages, access authentication and access
authorization, transport for short message service (SMS) messages
between the UE 204 and the short message service function (SMSF)
(not shown), and security anchor functionality (SEAF). The AMF also
interacts with the authentication server function (AUSF) (not
shown) and the UE 204, and receives the intermediate key that was
established as a result of the UE 204 authentication process. In
the case of authentication based on a UMTS (universal mobile
telecommunications system) subscriber identity module (USIM), the
AMF retrieves the security material from the AUSF. The functions of
the AMF also include security context management (SCM). The SCM
receives a key from the SEAF that it uses to derive access-network
specific keys. The functionality of the AMF also includes location
services management for regulatory services, transport for location
services messages between the UE 204 and the location management
function (LMF) 270, as well as between the New RAN 220 and the LMF
270, evolved packet system (EPS) bearer identifier allocation for
interworking with the EPS, and UE 204 mobility event notification.
In addition, the AMF also supports functionalities for non-3GPP
access networks.
[0057] Functions of the UPF include acting as an anchor point for
intra-/inter-RAT mobility (when applicable), acting as an external
protocol data unit (PDU) session point of interconnect to the data
network (not shown), providing packet routing and forwarding,
packet inspection, user plane policy rule enforcement (e.g.,
gating, redirection, traffic steering), lawful interception (user
plane collection), traffic usage reporting, quality of service
(QoS) handling for the user plane (e.g., UL/DL rate enforcement,
reflective QoS marking in the DL), uplink traffic verification
(service data flow (SDF) to QoS flow mapping), transport level
packet marking in the uplink and DL, downlink packet buffering and
downlink data notification triggering, and sending and forwarding
of one or more "end markers" to the source RAN node.
[0058] The functions of the SMF 262 include session management, UE
Internet protocol (IP) address allocation and management, selection
and control of user plane functions, configuration of traffic
steering at the UPF to route traffic to the proper destination,
control of part of policy enforcement and QoS, and downlink data
notification. The interface over which the SMF 262 communicates
with the AMF-side of the AMF/UPF 264 is referred to as the N11
interface.
[0059] Another optional aspect may include a LMF 270, which may be
in communication with the NGC 260 to provide location assistance
for UEs 204. The LMF 270 can be implemented as a plurality of
separate servers (e.g., physically separate servers, different
software modules on a single server, different software modules
spread across multiple physical servers, etc.), or alternately may
each correspond to a single server. The LMF 270 can be configured
to support one or more location services for UEs 204 that can
connect to the LMF 270 via the core network, NGC 260, and/or via
the Internet (not illustrated).
[0060] FIGS. 3A, 3B, and 3C illustrate several exemplary components
(represented by corresponding blocks) that may be incorporated into
a UE 302 (which may correspond to any of the UEs described herein),
a base station 304 (which may correspond to any of the base
stations described herein), and a network entity 306 (which may
correspond to or embody any of the network functions described
herein, including the location server 230 and the LMF 270) to
support the file transmission operations as taught herein. It will
be appreciated that these components may be implemented in
different types of apparatuses in different implementations (e.g.,
in an ASIC, in a system-on-chip (SoC), etc.). The illustrated
components may also be incorporated into other apparatuses in a
communication system. For example, other apparatuses in a system
may include components similar to those described to provide
similar functionality. Also, a given apparatus may contain one or
more of the components. For example, an apparatus may include
multiple transceiver components that enable the apparatus to
operate on multiple carriers and/or communicate via different
technologies.
[0061] The UE 302 and the base station 304 each include wireless
wide area network (WWAN) transceiver 310 and 350, respectively,
configured to communicate via one or more wireless communication
networks (not shown), such as an NR network, an LTE network, a GSM
network, and/or the like. The WWAN transceivers 310 and 350 may be
connected to one or more antennas 316 and 356, respectively, for
communicating with other network nodes, such as other UEs, access
points, base stations (e.g., eNBs, gNBs), etc., via at least one
designated RAT (e.g., NR, LTE, GSM, etc.) over a wireless
communication medium of interest (e.g., some set of time/frequency
resources in a particular frequency spectrum). The WWAN
transceivers 310 and 350 may be variously configured for
transmitting and encoding signals 318 and 358 (e.g., messages,
indications, information, and so on), respectively, and,
conversely, for receiving and decoding signals 318 and 358 (e.g.,
messages, indications, information, pilots, and so on),
respectively, in accordance with the designated RAT. Specifically,
the WWAN transceivers 310 and 350 include one or more transmitters
314 and 354, respectively, for transmitting and encoding signals
318 and 358, respectively, and one or more receivers 312 and 352,
respectively, for receiving and decoding signals 318 and 358,
respectively.
[0062] The UE 302 and the base station 304 also include, at least
in some cases, wireless local area network (WLAN) transceivers 320
and 360, respectively. The WLAN transceivers 320 and 360 may be
connected to one or more antennas 326 and 366, respectively, for
communicating with other network nodes, such as other UEs, access
points, base stations, etc., via at least one designated RAT (e.g.,
WiFi, LTE-D, Bluetooth.RTM., etc.) over a wireless communication
medium of interest. The WLAN transceivers 320 and 360 may be
variously configured for transmitting and encoding signals 328 and
368 (e.g., messages, indications, information, and so on),
respectively, and, conversely, for receiving and decoding signals
328 and 368 (e.g., messages, indications, information, pilots, and
so on), respectively, in accordance with the designated RAT.
Specifically, the WLAN transceivers 320 and 360 include one or more
transmitters 324 and 364, respectively, for transmitting and
encoding signals 328 and 368, respectively, and one or more
receivers 322 and 362, respectively, for receiving and decoding
signals 328 and 368, respectively.
[0063] Transceiver circuitry including at least one transmitter and
at least one receiver may comprise an integrated device (e.g.,
embodied as a transmitter circuit and a receiver circuit of a
single communication device) in some implementations, may comprise
a separate transmitter device and a separate receiver device in
some implementations, or may be embodied in other ways in other
implementations. In an aspect, a transmitter may include or be
coupled to a plurality of antennas (e.g., antennas 316, 326, 356,
366), such as an antenna array, that permits the respective
apparatus to perform transmit "beamforming," as described herein.
Similarly, a receiver may include or be coupled to a plurality of
antennas (e.g., antennas 316, 326, 356, 366), such as an antenna
array, that permits the respective apparatus to perform receive
beamforming, as described herein. In an aspect, the transmitter and
receiver may share the same plurality of antennas (e.g., antennas
316, 326, 356, 366), such that the respective apparatus can only
receive or transmit at a given time, not both at the same time. A
wireless communication device (e.g., one or both of the
transceivers 310 and 320 and/or 350 and 360) of the UE 302 and/or
the base station 304 may also comprise a network listen module
(NLM) or the like for performing various measurements.
[0064] The UE 302 and the base station 304 also include, at least
in some cases, satellite positioning systems (SPS) receivers 330
and 370, respectively. The SPS receivers 330 and 370 may be
connected to one or more antennas 336 and 376, respectively, for
receiving SPS signals 338 and 378, respectively, such as global
positioning system (GPS) signals, global navigation satellite
system (GLONASS) signals, Galileo signals, Beidou signals, Indian
Regional Navigation Satellite System (NAVIC), Quasi-Zenith
Satellite System (QZSS), etc. The SPS receivers 330 and 370 may
comprise any suitable hardware and/or software for receiving and
processing SPS signals 338 and 378, respectively. The SPS receivers
330 and 370 request information and operations as appropriate from
the other systems, and perform calculations necessary to determine
positions of the UE 302 and the base station 304, respectively,
using measurements obtained by any suitable SPS algorithm.
[0065] The base station 304 and the network entity 306 each include
at least one network interface 380 and 390, respectively, for
communicating with other network entities. For example, the network
interfaces 380 and 390 (e.g., one or more network access ports) may
be configured to communicate with one or more network entities via
a wire-based or wireless backhaul connection. In some aspects, the
network interfaces 380 and 390 may be implemented as transceivers
configured to support wire-based or wireless signal communication.
This communication may involve, for example, sending and receiving
messages, parameters, and/or other types of information.
[0066] The UE 302, the base station 304, and the network entity 306
also include other components that may be used in conjunction with
the operations as disclosed herein. The UE 302 includes processor
circuitry implementing a processing system 332 for providing
functionality relating to, for example, positioning operations, and
for providing other processing functionality. The base station 304
includes a processing system 384 for providing functionality
relating to, for example, positioning operations as disclosed
herein, and for providing other processing functionality. The
network entity 306 includes a processing system 394 for providing
functionality relating to, for example, positioning operations as
disclosed herein, and for providing other processing functionality.
In an aspect, the processing systems 332, 384, and 394 may include,
for example, one or more general purpose processors, multi-core
processors, ASICs, digital signal processors (DSPs), field
programmable gate arrays (FPGA), or other programmable logic
devices or processing circuitry.
[0067] The UE 302, the base station 304, and the network entity 306
include memory circuitry implementing memory components 340, 386,
and 396 (e.g., each including a memory device), respectively, for
maintaining information (e.g., information indicative of reserved
resources, thresholds, parameters, and so on). In some cases, the
UE 302, the base station 304, and the network entity 306 may
include positioning components 342, 388, and 398, respectively. The
positioning components 342, 388, and 398 may be hardware circuits
that are part of or coupled to the processing systems 332, 384, and
394, respectively, that, when executed, cause the UE 302, the base
station 304, and the network entity 306 to perform the
functionality described herein. In other aspects, the positioning
components 342, 388, and 398 may be external to the processing
systems 332, 384, and 394 (e.g., part of a modem processing system,
integrated with another processing system, etc.), respectively.
Alternatively, the positioning components 342, 388, and 398 may be
memory modules (as shown in FIGS. 3A-C) stored in the memory
components 340, 386, and 396, respectively, that, when executed by
the processing systems 332, 384, and 394 (or a modem processing
system, another processing system, etc.), cause the UE 302, the
base station 304, and the network entity 306 to perform the
functionality described herein.
[0068] The UE 302 may include one or more sensors 344 coupled to
the processing system 332 to provide movement and/or orientation
information that is independent of motion data derived from signals
received by the WWAN transceiver 310, the WLAN transceiver 320,
and/or the SPS receiver 330. By way of example, the sensor(s) 344
may include an accelerometer (e.g., a micro-electrical mechanical
systems (MEMS) device), a gyroscope, a geomagnetic sensor (e.g., a
compass), an altimeter (e.g., a barometric pressure altimeter),
and/or any other type of movement detection sensor. Moreover, the
sensor(s) 344 may include a plurality of different types of devices
and combine their outputs in order to provide motion information.
For example, the sensor(s) 344 may use a combination of a
multi-axis accelerometer and orientation sensors to provide the
ability to compute positions in 2D and/or 3D coordinate
systems.
[0069] In addition, the UE 302 includes a user interface 346 for
providing indications (e.g., audible and/or visual indications) to
a user and/or for receiving user input (e.g., upon user actuation
of a sensing device such a keypad, a touch screen, a microphone,
and so on). Although not shown, the base station 304 and the
network entity 306 may also include user interfaces.
[0070] Referring to the processing system 384 in more detail, in
the downlink, IP packets from the network entity 306 may be
provided to the processing system 384. The processing system 384
may implement functionality for an RRC layer, a packet data
convergence protocol (PDCP) layer, a radio link control (RLC)
layer, and a medium access control (MAC) layer. The processing
system 384 may provide RRC layer functionality associated with
broadcasting of system information (e.g., master information block
(MIB), system information blocks (SIBs)), RRC connection control
(e.g., RRC connection paging, RRC connection establishment, RRC
connection modification, and RRC connection release), inter-RAT
mobility, and measurement configuration for UE measurement
reporting; PDCP layer functionality associated with header
compression/decompression, security (ciphering, deciphering,
integrity protection, integrity verification), and handover support
functions; RLC layer functionality associated with the transfer of
upper layer packet data units (PDUs), error correction through
automatic repeat request (ARQ), concatenation, segmentation, and
reassembly of RLC service data units (SDUs), re-segmentation of RLC
data PDUs, and reordering of RLC data PDUs; and MAC layer
functionality associated with mapping between logical channels and
transport channels, scheduling information reporting, error
correction, priority handling, and logical channel
prioritization.
[0071] The transmitter 354 and the receiver 352 may implement
Layer-1 functionality associated with various signal processing
functions. Layer-1, which includes a physical (PHY) layer, may
include error detection on the transport channels, forward error
correction (FEC) coding/decoding of the transport channels,
interleaving, rate matching, mapping onto physical channels,
modulation/demodulation of physical channels, and MIMO antenna
processing. The transmitter 354 handles mapping to signal
constellations based on various modulation schemes (e.g., binary
phase-shift keying (BPSK), quadrature phase-shift keying (QPSK),
M-phase-shift keying (M-PSK), M-quadrature amplitude modulation
(M-QAM)). The coded and modulated symbols may then be split into
parallel streams. Each stream may then be mapped to an orthogonal
frequency division multiplexing (OFDM) subcarrier, multiplexed with
a reference signal (e.g., pilot) in the time and/or frequency
domain, and then combined together using an inverse fast Fourier
transform (IFFT) to produce a physical channel carrying a time
domain OFDM symbol stream. The OFDM symbol stream is spatially
precoded to produce multiple spatial streams. Channel estimates
from a channel estimator may be used to determine the coding and
modulation scheme, as well as for spatial processing. The channel
estimate may be derived from a reference signal and/or channel
condition feedback transmitted by the UE 302. Each spatial stream
may then be provided to one or more different antennas 356. The
transmitter 354 may modulate an RF carrier with a respective
spatial stream for transmission.
[0072] At the UE 302, the receiver 312 receives a signal through
its respective antenna(s) 316. The receiver 312 recovers
information modulated onto an RF carrier and provides the
information to the processing system 332. The transmitter 314 and
the receiver 312 implement Layer-1 functionality associated with
various signal processing functions. The receiver 312 may perform
spatial processing on the information to recover any spatial
streams destined for the UE 302. If multiple spatial streams are
destined for the UE 302, they may be combined by the receiver 312
into a single OFDM symbol stream. The receiver 312 then converts
the OFDM symbol stream from the time-domain to the frequency domain
using a fast Fourier transform (FFT). The frequency domain signal
comprises a separate OFDM symbol stream for each subcarrier of the
OFDM signal. The symbols on each subcarrier, and the reference
signal, are recovered and demodulated by determining the most
likely signal constellation points transmitted by the base station
304. These soft decisions may be based on channel estimates
computed by a channel estimator. The soft decisions are then
decoded and de-interleaved to recover the data and control signals
that were originally transmitted by the base station 304 on the
physical channel. The data and control signals are then provided to
the processing system 332, which implements Layer-3 and Layer-2
functionality.
[0073] In the UL, the processing system 332 provides demultiplexing
between transport and logical channels, packet reassembly,
deciphering, header decompression, and control signal processing to
recover IP packets from the core network. The processing system 332
is also responsible for error detection.
[0074] Similar to the functionality described in connection with
the downlink transmission by the base station 304, the processing
system 332 provides RRC layer functionality associated with system
information (e.g., MIB, SIBS) acquisition, RRC connections, and
measurement reporting; PDCP layer functionality associated with
header compression/decompression, and security (ciphering,
deciphering, integrity protection, integrity verification); RLC
layer functionality associated with the transfer of upper layer
PDUs, error correction through ARQ, concatenation, segmentation,
and reassembly of RLC SDUs, re-segmentation of RLC data PDUs, and
reordering of RLC data PDUs; and MAC layer functionality associated
with mapping between logical channels and transport channels,
multiplexing of MAC SDUs onto transport blocks (TBs),
demultiplexing of MAC SDUs from TBs, scheduling information
reporting, error correction through hybrid automatic repeat request
(HARD), priority handling, and logical channel prioritization.
[0075] Channel estimates derived by the channel estimator from a
reference signal or feedback transmitted by the base station 304
may be used by the transmitter 314 to select the appropriate coding
and modulation schemes, and to facilitate spatial processing. The
spatial streams generated by the transmitter 314 may be provided to
different antenna(s) 316. The transmitter 314 may modulate an RF
carrier with a respective spatial stream for transmission.
[0076] The uplink transmission is processed at the base station 304
in a manner similar to that described in connection with the
receiver function at the UE 302. The receiver 352 receives a signal
through its respective antenna(s) 356. The receiver 352 recovers
information modulated onto an RF carrier and provides the
information to the processing system 384.
[0077] In the UL, the processing system 384 provides demultiplexing
between transport and logical channels, packet reassembly,
deciphering, header decompression, control signal processing to
recover IP packets from the UE 302. IP packets from the processing
system 384 may be provided to the core network. The processing
system 384 is also responsible for error detection.
[0078] For convenience, the UE 302, the base station 304, and/or
the network entity 306 are shown in FIGS. 3A-C as including various
components that may be configured according to the various examples
described herein. It will be appreciated, however, that the
illustrated blocks may have different functionality in different
designs.
[0079] The various components of the UE 302, the base station 304,
and the network entity 306 may communicate with each other over
data buses 334, 382, and 392, respectively. The components of FIGS.
3A-C may be implemented in various ways. In some implementations,
the components of FIGS. 3A-C may be implemented in one or more
circuits such as, for example, one or more processors and/or one or
more ASICs (which may include one or more processors). Here, each
circuit may use and/or incorporate at least one memory component
for storing information or executable code used by the circuit to
provide this functionality. For example, some or all of the
functionality represented by blocks 310 to 346 may be implemented
by processor and memory component(s) of the UE 302 (e.g., by
execution of appropriate code and/or by appropriate configuration
of processor components). Similarly, some or all of the
functionality represented by blocks 350 to 388 may be implemented
by processor and memory component(s) of the base station 304 (e.g.,
by execution of appropriate code and/or by appropriate
configuration of processor components). Also, some or all of the
functionality represented by blocks 390 to 398 may be implemented
by processor and memory component(s) of the network entity 306
(e.g., by execution of appropriate code and/or by appropriate
configuration of processor components). For simplicity, various
operations, acts, and/or functions are described herein as being
performed "by a UE," "by a base station," "by a positioning
entity," etc. However, as will be appreciated, such operations,
acts, and/or functions may actually be performed by specific
components or combinations of components of the UE, base station,
positioning entity, etc., such as the processing systems 332, 384,
394, the transceivers 310, 320, 350, and 360, the memory components
340, 386, and 396, the positioning components 342, 388, and 398,
etc.
[0080] Various frame structures may be used to support downlink and
uplink transmissions between network nodes (e.g., base stations and
UEs). FIG. 4A is a diagram 400 illustrating an example of a
downlink frame structure, according to aspects of the disclosure.
FIG. 4B is a diagram 430 illustrating an example of channels within
the downlink frame structure, according to aspects of the
disclosure. FIG. 4C is a diagram 450 illustrating an example of an
uplink frame structure, according to aspects of the disclosure.
FIG. 4D is a diagram 480 illustrating an example of channels within
an uplink frame structure, according to aspects of the disclosure.
Other wireless communications technologies may have different frame
structures and/or different channels.
[0081] LTE, and in some cases NR, utilizes OFDM on the downlink and
single-carrier frequency division multiplexing (SC-FDM) on the
uplink. Unlike LTE, however, NR has an option to use OFDM on the
uplink as well. OFDM and SC-FDM partition the system bandwidth into
multiple (K) orthogonal subcarriers, which are also commonly
referred to as tones, bins, etc. Each subcarrier may be modulated
with data. In general, modulation symbols are 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 (K) may be dependent on the system bandwidth. For
example, the spacing of the subcarriers may be 15 kHz and the
minimum resource allocation (resource block) may be 12 subcarriers
(or 180 kHz). Consequently, the nominal FFT size may be equal to
128, 256, 512, 1024, or 2048 for system bandwidth of 1.25, 2.5, 5,
10, or 20 megahertz (MHz), respectively. The system bandwidth may
also be partitioned into subbands. For example, a subband may cover
1.08 MHz (i.e., 6 resource blocks), and there may be 1, 2, 4, 8, or
16 subbands for system bandwidth of 1.25, 2.5, 5, 10, or 20 MHz,
respectively.
[0082] LTE supports a single numerology (subcarrier spacing, symbol
length, etc.). In contrast, NR may support multiple numerologies
(.mu.), for example, subcarrier spacing of 15 kHz, 30 kHz, 60 kHz,
120 kHz, and 240 kHz or greater may be available. Table 1 provided
below lists some various parameters for different NR
numerologies.
TABLE-US-00001 TABLE 1 Max. nominal Subcarrier slots/ Symbol system
BW spacing Symbols/ sub- slots/ slot duration (MHz) with (kHz) slot
frame frame (ms) (hs) 4K FFT size 15 14 1 10 1 66.7 50 30 14 2 20
0.5 33.3 100 60 14 4 40 0.25 16.7 100 120 14 8 80 0.125 8.33 400
240 14 16 160 0.0625 4.17 800
[0083] In the examples of FIGS. 4A to 4D, a numerology of 15 kHz is
used. Thus, in the time domain, a frame (e.g., 10 ms) is divided
into 10 equally sized subframes of 1 ms each, and each subframe
includes one time slot. In FIGS. 4A to 4D, time is represented
horizontally (e.g., on the X axis) with time increasing from left
to right, while frequency is represented vertically (e.g., on the Y
axis) with frequency increasing (or decreasing) from bottom to
top.
[0084] A resource grid may be used to represent time slots, each
time slot including one or more time concurrent resource blocks
(RBs) (also referred to as physical RBs (PRBs)) in the frequency
domain. The resource grid is further divided into multiple resource
elements (REs). An RE may correspond to one symbol length in the
time domain and one subcarrier in the frequency domain. In the
numerology of FIGS. 4A to 4D, for a normal cyclic prefix, an RB may
contain 12 consecutive subcarriers in the frequency domain and
seven consecutive symbols in the time domain, for a total of 84
REs. For an extended cyclic prefix, an RB may contain 12
consecutive subcarriers in the frequency domain and six consecutive
symbols in the time domain, for a total of 72 REs. The number of
bits carried by each RE depends on the modulation scheme.
[0085] As illustrated in FIG. 4A, some of the REs carry downlink
reference (pilot) signals (DL-RS) for channel estimation at the UE.
The DL-RS may include demodulation reference signals (DMRS),
channel state information reference signals (CSI-RS), cell-specific
reference signals (CRS), positioning reference signals (PRS),
navigation reference signals (NRS), tracking reference signals
(TRS), etc., exemplary locations of which are labeled "R" in FIG.
4A.
[0086] A collection of resource elements that are used for
transmission of PRS is referred to as a "PRS resource," and may be
identified by the parameter DL-PRS-ResourceId. The collection of
resource elements (REs) can span multiple PRBs in the frequency
domain and N (e.g., 1 or more) consecutive symbol(s) within a slot
in the time domain. In a given OFDM symbol in the time domain, a
PRS resource occupies consecutive PRBs in the frequency domain.
[0087] A "PRS resource set" is a set of PRS resources used for the
transmission of PRS signals, where each PRS resource has a PRS
resource ID (DL-PRS-ResourceId). In addition, the PRS resources in
a PRS resource set are associated with the same TRP. A PRS resource
set is identified by a PRS resource set ID (DL-PRS-ResourceSetId)
and is associated with a particular TRP (identified by a cell ID).
In addition, the PRS resources in a PRS resource set have the same
periodicity, a common muting pattern configuration, and the same
repetition factor across slots. The periodicity may have a length
of 2.sup..mu.t slots, with t selected from a set of {4, 5, 8, 10,
16, 20, 32, 40, 64, 80, 160, 320, 640, 1280, 2560, 5120, 10240},
and .mu.=0, 1, 2, or 3 (an identifier of the numerology). The
repetition factor may have a length of n slots, with n selected
from a set of {1, 2, 4, 6, 8, 16, 32}.
[0088] A PRS resource ID in a PRS resource set is associated with a
single beam (and/or beam ID) transmitted from a single TRP (where a
TRP may transmit one or more beams). That is, each PRS resource of
a PRS resource set may be transmitted on a different beam, and as
such, a "PRS resource," or simply "resource," can also be referred
to as a "beam." Note that this does not have any implications on
whether the TRPs and the beams on which PRS are transmitted are
known to the UE.
[0089] A "PRS instance" or "PRS occasion" is one instance of a
periodically repeated time window (e.g., a group of one or more
consecutive slots) where PRS are expected to be transmitted. A PRS
occasion may also be referred to as a "PRS positioning occasion," a
"PRS positioning instance," a "positioning occasion," "a
positioning instance," or simply an "occasion" or "instance."
[0090] A "positioning frequency layer" is a collection of one or
more PRS resource sets across one or more TRPs that have the same
subcarrier spacing (SCS) and cyclic prefix (CP) type (meaning all
numerologies supported for the physical downlink shared channel
(PDSCH) are also supported for PRS), the same Point A, the same
value of the downlink PRS bandwidth, the same start PRB (and center
frequency), and the same value of comb-size. The Point A parameter
takes the value of the parameter ARFCN-ValueNR, where "ARFCN"
stands for "absolute radio-frequency channel number," and is an
identifier/code that specifies a pair of physical radio channel
used for transmission and reception. The downlink PRS bandwidth may
have a granularity of four PRBs, with a minimum of 24 PRBs and a
maximum of 272 PRBs. The comb-size indicates the number of
subcarriers in each symbol carrying PRS. For example, a comb-size
of comb-4 means that every fourth subcarrier of a given symbol
carries PRS. Currently, up to four frequency layers have been
defined, and up to two PRS resource sets may be configured per TRP
per frequency layer.
[0091] Downlink PRS resource IDs are locally defined within a
downlink PRS resource set, and downlink PRS resource set IDs are
locally defined within a TRP. To uniquely identify a DL-PRS
resource across TRPs, an ID has been defined that can be associated
with multiple downlink PRS resource sets associated with a single
TRP. This ID can be used along with a downlink PRS resource set ID
and a downlink PRS resource ID to uniquely identify a single
downlink PRS resource. This ID is referred to herein as
DL-PRS-TRP-ResourceSetId. Each TRP should only be associated with
one DL-PRS-TRP-ResourceSetId. For example, a
DL-PRS-TRP-ResourceSetId may be a cell ID (e.g., PCI, VCI), or a
TRP ID, or another identifier that is different than the cell ID or
the TRP ID that is used for positioning purposes to participate in
the unique identification of a PRS resource.
[0092] Note that the terms "positioning reference signal" and "PRS"
may sometimes refer to specific reference signals that are used for
positioning in LTE systems. However, as used herein, unless
otherwise indicated, the terms "positioning reference signal" and
"PRS" refer to any type of reference signal that can be used for
positioning, such as but not limited to, PRS signals in LTE, NRS,
TRS, CRS, CSI-RS, DMRS, primary synchronization signal (PSS),
secondary synchronization signal (SSS), etc.
[0093] FIG. 4B illustrates an example of various channels within a
downlink slot of a radio frame. In NR, the channel bandwidth, or
system bandwidth, is divided into multiple bandwidth parts (BWPs).
A BWP is a contiguous set of PRBs selected from a contiguous subset
of the common RBs for a given numerology on a given carrier.
Generally, a maximum of four BWPs can be specified in the downlink
and uplink. That is, a UE can be configured with up to four BWPs on
the downlink, and up to four BWPs on the uplink. Only one BWP
(uplink or downlink) may be active at a given time, meaning that
the UE may only receive or transmit over one BWP at a time. On the
downlink, the bandwidth of each BWP should be equal to or greater
than the bandwidth of the SSB, but it may or may not contain the
SSB.
[0094] Referring to FIG. 4B, a PSS is used by a UE to determine
subframe/symbol timing and a physical layer identity. An SSS is
used by a UE to determine a physical layer cell identity group
number and radio frame timing. Based on the physical layer identity
and the physical layer cell identity group number, the UE can
determine a PCI. Based on the PCI, the UE can determine the
locations of the aforementioned DL-RS. The physical broadcast
channel (PBCH), which carries an MIB, may be logically grouped with
the PSS and SSS to form an SSB (also referred to as an SS/PBCH).
The MIB provides a number of RBs in the downlink system bandwidth
and a system frame number (SFN). The PDSCH carries user data,
broadcast system information not transmitted through the PBCH, such
as system information blocks (SIBs), and paging messages.
[0095] The physical downlink control channel (PDCCH) carries
downlink control information (DCI) within one or more control
channel elements (CCEs), each CCE including one or more RE group
(REG) bundles (which may span multiple symbols in the time domain),
each REG bundle including one or more REGs, each REG corresponding
to 12 resource elements (one resource block) in the frequency
domain and one OFDM symbol in the time domain. The set of physical
resources used to carry the PDCCH/DCI is referred to in NR as the
control resource set (CORESET). In NR, a PDCCH is confined to a
single CORESET and is transmitted with its own DMRS. This enables
UE-specific beamforming for the PDCCH.
[0096] In the example of FIG. 4B, there is one CORESET per BWP, and
the CORESET spans three symbols in the time domain. Unlike LTE
control channels, which occupy the entire system bandwidth, in NR,
PDCCH channels are localized to a specific region in the frequency
domain (i.e., a CORESET). Thus, the frequency component of the
PDCCH shown in FIG. 4B is illustrated as less than a single BWP in
the frequency domain. Note that although the illustrated CORESET is
contiguous in the frequency domain, it need not be. In addition,
the CORESET may span less than three symbols in the time
domain.
[0097] The DCI within the PDCCH carries information about uplink
resource allocation (persistent and non-persistent) and
descriptions about downlink data transmitted to the UE. Multiple
(e.g., up to eight) DCIs can be configured in the PDCCH, and these
DCIs can have one of multiple formats. For example, there are
different DCI formats for uplink scheduling, for non-MIMO downlink
scheduling, for MIMO downlink scheduling, and for uplink power
control. A PDCCH may be transported by 1, 2, 4, 8, or 16 CCEs in
order to accommodate different DCI payload sizes or coding
rates.
[0098] As illustrated in FIG. 4C, some of the REs carry DMRS for
channel estimation at the base station. The UE may additionally
transmit sounding reference signals (SRS) in, for example, the last
symbol of a subframe. The SRS may have a comb structure, and a UE
may transmit SRS on one of the combs. The comb structure (also
referred to as the "comb size") indicates the number of subcarriers
in each symbol period carrying a reference signal (here, SRS). For
example, a comb size of comb-4 means that every fourth subcarrier
of a given symbol carries the reference signal, whereas a comb size
of comb-2 means that every second subcarrier of a given symbol
carries the reference signal. In the example of FIG. 4C, the
illustrated SRS (e.g., SRS #0 and SRS #1) are both comb-2. The SRS
may be used by a base station to obtain the channel state
information (CSI) for each UE. CSI describes how an RF signal
propagates from the UE to the base station and represents the
combined effect of scattering, fading, and power decay with
distance. The system uses the SRS for resource scheduling, link
adaptation, massive MIMO, beam management, etc.
[0099] FIG. 4D illustrates an example of various channels within an
uplink subframe of a frame, according to aspects of the disclosure.
A random access channel (RACH), also referred to as a physical
random access channel (PRACH), may be within one or more subframes
within a frame based on the PRACH configuration. The PRACH may
include six consecutive RB pairs within a subframe. The PRACH
allows the UE to perform initial system access and achieve uplink
synchronization. A physical uplink control channel (PUCCH) may be
located on edges of the uplink system bandwidth. The PUCCH carries
uplink control information (UCI), such as scheduling requests, CSI
reports, a channel quality indicator (CQI), a precoding matrix
indicator (PMI), a rank indicator (RI), and HARQ ACK/NACK feedback.
The physical uplink shared channel (PUSCH) carries data, and may
additionally be used to carry a buffer status report (BSR), a power
headroom report (PHR), and/or UCI.
[0100] A collection of resource elements that are used for
transmission of SRS is referred to as an "SRS resource," and may be
identified by the parameter SRS-ResourceId. The collection of
resource elements can span multiple PRBs in the frequency domain
and N (e.g., one or more) consecutive symbol(s) within a slot in
the time domain. In a given OFDM symbol, an SRS resource occupies
consecutive PRBs. An "SRS resource set" is a set of SRS resources
used for the transmission of SRS signals, and is identified by an
SRS resource set ID (SRS-ResourceSetId).
[0101] Generally, a UE transmits SRS to enable the receiving base
station (either the serving base station or a neighboring base
station) to measure the channel quality between the UE and the base
station. However, SRS can also be used as uplink positioning
reference signals for uplink positioning procedures, such as uplink
time-difference of arrival (UTDOA), multi-round-trip-time
(multi-RTT), uplink angle-of-arrival (UL-AoA), etc.
[0102] FIG. 5A illustrates an exemplary four-step random access
procedure 500A, according to aspects of the disclosure. The
four-step random access procedure 500A is performed between a UE
504 and a base station 502, which may correspond to any of the UEs
and base stations, respectively, described herein.
[0103] There are various situations in which a UE may perform the
four-step random access procedure 500A (also referred to as a "RACH
procedure," a "PRACH procedure," and the like). For example, a UE
may perform the four-step random access procedure 500A when
acquiring initial network access after coming out of the RRC idle
state, when performing an RRC connection re-establishment
procedure, during a handover, when downlink or uplink data arrives
and the UE is in an RRC connected state but its uplink
synchronization status is "not-synchronized," when transitioning
out of the RRC INACTIVE state, when establishing time alignment for
the addition of an SCell, when requesting other synchronization
information, or when performing beam failure recovery.
[0104] Before performing the four-step random access procedure
500A, the UE 504 first reads one or more SSBs broadcasted by the
base station 502 with which the UE 504 is performing the four-step
random access procedure 500A. In NR, each beam transmitted by a
base station (e.g., base station 502) is associated with a
different SSB, and a UE (e.g., UE 504) selects a certain beam to
use to communicate with the base station 502. Based on the SSB of
the selected beam, the UE 504 can then read the SIB type 1 (SIB1),
which carries cell access related information and supplies the UE
504 with the scheduling of other system information blocks
transmitted on the selected beam.
[0105] When the UE sends the very first message of the four-step
random access procedure 500A to the base station 502, it sends a
specific pattern called a preamble (also referred to as a RACH
preamble, a PRACH preamble, a preamble sequence, or a sequence).
The RACH preamble differentiates requests from different UEs 504.
However, if two UEs 504 use the same RACH preamble at the same
time, then there can be a collision. There are a total of 64 such
patterns available to a UE 504, and, for contention-based random
access, the UE 504 chooses one of them randomly. For
contention-free random access, however, the network instructs the
UE 504 about which one to use.
[0106] At 510, the UE 504 selects one of 64 RACH preambles to send
to the base station 502 as a RACH request. This message is referred
to as "Message 1" or "Msg1" in a four-step RACH procedure. Based on
the synchronization information from the base station 502 (i.e.,
the SIB1), the UE 504 selects a RACH preamble and sends it at the
RACH occasion (RO) corresponding to the selected SSB/beam. More
specifically, in order for the base station 502 to determine which
beam the UE 504 has selected, a specific mapping is defined between
an SSB and an RO (which occur every 10, 20, 40, 80, or 160 ms). By
detecting at which RO the UE 504 sent the preamble, the base
station 502 can determine which SSB/beam the UE 504 selected.
[0107] Note that an RO is a time-frequency transmission opportunity
for transmitting a RACH preamble, and a RACH preamble index (i.e.,
a value from 0 to 63 for the 64 possible preambles) enables the UE
504 to generate the type of RACH preamble expected at the base
station 502. The RO and RACH preamble index may be configured to
the UE 504 by the base station 502 in a SIB. A RACH resource is an
RO in which one RACH preamble index is transmitted. As such, the
terms "RO" (or "RACH occasion") and "RACH resource" may be used
interchangeably, depending on the context.
[0108] Due to reciprocity, the UE 504 may use the uplink transmit
beam corresponding to the best downlink receive beam determined
during synchronization (i.e., the best receive beam to receive the
selected downlink beam from the base station 502). That is, the UE
504 uses the parameters of the downlink receive beam used to
receive the beam from the base station 502 to determine the
parameters of the uplink transmit beam. If reciprocity is available
at the base station 502, the UE 504 can transmit the preamble over
one beam. Otherwise, the UE 504 repeats transmission of the same
preamble on all of its uplink transmit beams.
[0109] The UE 504 also needs to provide its identity to the network
(via base station 502) so that the network can address it in the
next step. This identity is called the random access radio network
temporary identity (RA-RNTI) and is determined from the time slot
in which the RACH preamble is sent. If the UE 504 does not receive
any response from the base station 502 within some period of time,
it increases its transmission power in a fixed step and sends the
RACH preamble/Msg1 again.
[0110] At 520, the base station 502 sends a random access response
(RAR), referred to as a "Message 2" or "Msg2" in a four-step RACH
procedure, to the UE 504 on the selected beam. The RAR is sent on a
PDSCH and is addressed to the RA-RNTI calculated from the time slot
(i.e., RO) in which the preamble was sent. The RAR carries the
following information: a cell-radio network temporary identifier
(C-RNTI), a timing advance (TA) value, and an uplink grant
resource. The base station 502 assigns the C-RNTI to the UE 504 to
enable further communication with the UE 504. The TA value
specifies how much the UE 504 should change its timing to
compensate for the round-trip delay between the UE 504 and the base
station 502. The uplink grant resource indicates the initial
resources the UE 504 can use on the PUSCH. After this step, the UE
504 and the base station 502 establish coarse beam alignment that
can be utilized in the subsequent steps.
[0111] At 530, using the allocated PUSCH, the UE 504 sends an RRC
connection request message, referred to as a "Message 3" or "Msg3,"
to the base station 502. Because the UE 504 sends the Msg3 over the
resources scheduled by the base station 502, the base station 502
therefore knows where to detect the Msg3 and which uplink receive
beam should be used. Note that the Msg3 PUSCH can be sent on the
same or different uplink transmit beam than the Msg1.
[0112] The UE 504 identifies itself in the Msg3 by the C-RNTI
assigned in the previous step. The message contains the UE's 504
identity and connection establishment cause. The UE's 504 identity
is either a temporary mobile subscriber identity (TMSI) or a random
value. A TMSI is used if the UE 504 has previously connected to the
same network. The UE 504 is identified in the core network by the
TMSI. A random value is used if the UE 504 is connecting to the
network for the very first time. The reason for the random value or
TMSI is that the C-RNTI may have been assigned to more than one UE
in the previous step, due to multiple requests arriving at the same
time. The connection establishment cause indicates the reason why
the UE 504 needs to connect to the network, and will be described
further below.
[0113] At 540, if the Msg3 was successfully received, the base
station 502 responds with a contention resolution message, referred
to as a "Message 4" or "Msg4." This message is addressed to the
TMSI or random value (from the Msg3) but contains a new C-RNTI that
will be used for further communication. Specifically, the base
station 502 sends the Msg4 in the PDSCH using the downlink transmit
beam determined in the previous step.
[0114] The four-step random access procedure 500A described above
is a contention-based random access procedure. In contention-based
random access, any UE 504 connecting to the same cell or TRP sends
the same request, in which case there is a possibility of collision
among the requests from the various UEs 504. In contention-free
random access, the network can instruct a UE 504 to use some unique
identity to prevent its request from colliding with requests from
other UEs. A contention-free random access procedure can be
performed when the UE 504 is in an RRC connected mode before the
random access procedure, such as in the case of a handover.
[0115] FIG. 5B illustrates an exemplary two-step random access
procedure 500B, according to aspects of the disclosure. The
two-step random access procedure 500B is performed between the UE
504 and the base station 502.
[0116] At 550, the UE 504 transmits a RACH Message A ("MsgA") to
the base station 502. In a two-step random access procedure 500B,
Msg1 and Msg3, described above with reference to FIG. 5A, are
collapsed (e.g., combined) into MsgA and sent to the base station
502. As such, a MsgA includes a RACH preamble and a PUSCH, similar
to the Msg3 PUSCH of a four-step RACH procedure. The RACH preamble
may have been selected from 64 possible preambles, as described
above with reference to FIG. 5A, and may be used as a reference
signal for demodulation of the data transmitted in the MsgA. At
560, the UE 504 receives a RACH Message B ("MsgB") from the base
station 502. The MsgB may be a combination of Msg2 and Msg4
described above with reference to FIG. 5A.
[0117] The combination of Msg1 and Msg3 into one MsgA and the
combination of Msg2 and Msg4 into one MsgB allows the UE 504 to
reduce the RACH procedure setup time to support the low-latency
requirements of 5G NR. Although the UE 504 may be configured to
support the two-step random access procedure 500B, the UE 504 may
still support the four-step random access procedure 500A as a fall
back if the UE 504 is not be able to use the two-step random access
procedure 500B due to some constraints (e.g., high transmit power
requirements, etc.). Therefore, a UE in 5G NR may be configured to
support both the two-step and the four-step random access
procedures, and may determine which random access procedure to
configure based on the RACH configuration information received from
the base station.
[0118] After the random access procedure 500A or 500B, the UE 504
is in an RRC connected state. The RRC protocol is used on the air
interface between the UE 504 and the base station 502.
[0119] Due to UE mobility/movement, beam reconfiguration at the
base station, and/or other factors, a downlink beam (e.g.,
comprising a downlink control link), which may have been the
preferred active beam, may fail to be detected at the UE, or the
signal quality (e.g., RSRP, RSRQ, SINR, etc.) may fall below a
threshold, causing the UE to consider it as a beam/link failure. A
beam recovery procedure may be employed to recover from such a beam
failure. A beam failure may refer to, for example, failure to
detect a strong (e.g., with signal power greater than a threshold)
active beam, which may, in some aspects, correspond to a control
channel communicating control information from the network. In
certain aspects, in order to facilitate beam failure detection, a
UE may be preconfigured with beam identifiers (IDs) of a first set
of beams (referred to as "set_q0") to be monitored, a monitoring
period, a signal strength threshold, etc. The recovery may be
triggered when a signal strength (e.g., RSRP, RSRQ, SINR, etc.)
associated with the one or more monitored beams (as detected by the
UE) falls below a threshold. The recovery process may include the
UE identifying a new beam, for example, from a second set of
possible beams (corresponding to beam IDs that may be included in a
second set, referred to as "set_q1"), and performing a random
access procedure (e.g., as illustrated in FIGS. 5A and 5B) using
preconfigured time and frequency resources corresponding to the new
preferred beam. The beam IDs corresponding to the beams in the
second set of beams (set_q1) may be preconfigured at the UE for use
for beam failure recovery purposes. For example, the UE may monitor
downlink beams (based on the beam IDs and resources identified in
the second set), perform measurements, and determine (e.g., based
on the measurements) which beam out of all received and measured
beams may be the best for reception at the UE from the UE's
perspective.
[0120] If beam correspondence is assumed (i.e., the direction of
the best receive beam used by the UE is also considered the best
direction for the transmit beam used by the UE), then the UE may
assume the same beam configuration for both reception and
transmission. That is, based on monitoring downlink reference
signals from the base station, the UE can determine its preferred
uplink transmit beam weights, which will be the same as for the
downlink receive beam used for receiving the downlink reference
signals.
[0121] Where beam correspondence is not assumed (e.g., deemed not
suitable in the given scenario or for other reasons), the UE may
not derive the uplink transmit beam from the downlink receive beam.
Instead, separate signaling is needed to select the uplink transmit
and downlink receive beam weights and for the UL-to-DL beam
pairing. The UE may perform a RACH procedure (e.g., using the
preconfigured time and frequency resources indicated in the second
set of beams, set_q1) to identify the uplink transmit beam.
Performing the RACH procedure using the preconfigured time and
frequency resources may comprise, for example, transmitting a RACH
preamble on one or more uplink transmit beams (corresponding to the
beam IDs in the second set of beams, set_q1) on allocated RACH
resources corresponding to the one or more beams. Based on the RACH
procedure, the UE may be able to determine and confirm with the
base station which uplink direction may be the best beam direction
for an uplink channel (e.g., PUCCH). In this manner, both uplink
transmit and downlink receive beams may be reestablished and beam
recovery may be completed.
[0122] FIG. 6 is a diagram 600 of an exemplary RACH-based SpCell
beam failure recovery procedure, according to aspects of the
disclosure. In the example of FIG. 6, for simplicity, the PCell and
SCell are shown to be associated with a single base station (e.g.,
the hardware/circuitry for implementing the PCell and SCell may be
collocated at the same base station). However, in some other
configurations, the PCell and SCell may be associated with
different base stations that may be synchronized.
[0123] In the example of FIG. 6, a PCell or a primary (i.e., in
active use) SCell (together referred to as an "SpCell") is
supported by a base station 602 (illustrated as a "gNB," and which
may correspond to any of the base stations described herein). A UE
604 (which may correspond to any of the UEs described herein)
monitors the received signal strength (e.g., RSRP, RSRQ, SINR,
etc.) of periodic reference signals (e.g., PRS) transmitted by the
base station 602 on a first set ("set_q0") of downlink transmit
beams 606 of the SpCell. The first set of downlink transmit beams
606 is referred to as the "failure detection resource set" because
the base station 602 sends the beam IDs of the beams in the first
set of downlink transmit beams 606 to the UE 604 to enable the UE
604 to monitor these beams to determine whether or not the downlink
control link (i.e., a control channel communicating control
information from the network) between the base station 602 and the
UE 604 is active. In the example of FIG. 6, the first set of
downlink transmit beams 606 includes two beams. However, there may
be only one beam or more than two beams in the first set of
downlink transmit beams 606.
[0124] At 610, the UE 604 fails to detect a periodic reference
signal transmitted on at least one of the beams in the first set of
downlink transmit beams 606, and/or detects that a quality metric
(e.g., RSRP, RSRQ, SINR, etc.) associated with the reference signal
has fallen below a signal quality threshold (represented in FIG. 6
as "Qout"). The Qout threshold may be configured by the base
station 602. More specifically, the Layer 1 ("L1" in FIG. 6)
functionality of the UE 604 (e.g., implemented in the WWAN
transceiver 310) detects that the measured quality metric of the
periodic reference signal is below the Qout threshold, and sends an
out-of-sync (OOS) indication to the processing system 332 (which
implements the Layer 2 and Layer 3 functionality of the UE 604). In
response to receiving the OOS indication, the processing system 332
of the UE 604 starts a beam failure detection (BFD) timer and
initializes a beam failure indicator (BFI) counter to "1."
[0125] At 615, the UE 604 again fails to detect the periodic
reference signal transmitted on the at least one of the beams in
the first set of downlink transmit beams 606, and/or again detects
that the quality metric associated with the reference signal has
fallen below the Qout threshold. Again, more specifically, the
Layer 1 functionality of the UE 604 detects that the measured
quality metric of the periodic reference signal is below the Qout
threshold, and sends another OOS indication to the processing
system 332. The processing system 332 increments the BFI count to
"2." Because the BFI count has reached the maximum count ("MaxCnt")
threshold (which is "2" in the example of FIG. 6 but which may be
another value) while the BFD timer is running, the UE 604
determines that there has been a beam failure of the at least one
beam (e.g., a downlink control beam) in the first set of downlink
transmit beams 606. Because there is a failure of a downlink
control beam (corresponding to the downlink control channel
communicating control information from the network), the UE 604
assumes that there is also a failure of the corresponding uplink
control beam (corresponding to the uplink control channel for
communicating control information to the network). As such, the UE
604 needs to identify a new downlink control beam and re-establish
an uplink control beam. The UE 604 also resets the BFD timer.
[0126] Thus, at 620, in response to the beam failure detection at
615, the UE 604 initiates a beam failure recovery procedure. More
specifically, the processing system 332 of the UE 604 requests that
the Layer 1 functionality of the UE 604 identify at least one beam
in a second set ("set_q1") of downlink transmit beams 608 that
carries a periodic reference signal with a received signal strength
greater than a signal quality threshold (represented as "Qin"). The
second set of downlink transmit beams 608 is referred to as the
"candidate beam reference signal list." The UE 604 may receive both
the beam IDs of the beams in the second set of downlink transmit
beams 608 and the Qin threshold from the base station 602. In the
example of FIG. 6, the second set of downlink transmit beams 608
includes four beams, one of which (shaded) carries periodic
reference signals having a received signal strength greater than
the Qin threshold. However, as will be appreciated, there may be
more or fewer than four beams in the second set of downlink
transmit beams 608, and there may be more than one beam that meets
the Qin threshold. The WWAN transceiver 310 (implementing Layer 1
functionality) reports the identified candidate beam to the
processing system 332. The identified candidate beam can then be
used as the new downlink control beam, although not necessarily
immediately.
[0127] At 625, to re-establish an uplink control beam, the UE 604
performs a RACH procedure (e.g., as illustrated in FIGS. 5A and 5B)
on the one or more candidate downlink transmit beams identified at
620 (one in the example of FIG. 6). More specifically, the
processing system 332 instructs the WWAN transceiver 310 to send a
RACH preamble (which may be pre-stored or provided to the UE 604 by
the base station 602) to the base station 602. The WWAN transceiver
310 sends the RACH preamble (also referred to as a Message 1
("Msg1")) on one or more candidate uplink transmit beams
corresponding to the one or more candidate downlink transmit beams
identified at 620 on preconfigured RACH resources for the one or
more candidate uplink transmit beams. The preconfigured RACH
resources may correspond to the SpCell (e.g., in the mmW band).
Although not illustrated in FIG. 6, at 625, the UE 604 also starts
a beam failure recovery (BFR) timer that defines a contention-free
random access (CFRA) response window.
[0128] The one or more candidate downlink transmit beams identified
at 620 can include beams that are different than the downlink
transmit beam associated with the beam failure. As used herein, a
"beam" is defined by beam weights associated with an antenna array
of the UE 604. Hence, in some aspects, whether used for uplink
transmission by the UE 604 or downlink reception by the UE 604, the
weights applied to each antenna in the array to construct the
transmitted or received beam define the beam. As such, the one or
more candidate uplink transmit beams on which the RACH preamble is
sent may have different weights than the downlink transmit beam
associated with the beam failure, even if such candidate uplink
transmit beam is in generally a similar direction as the downlink
transmit beam indicated to be failing.
[0129] At 630, the base station 602 transmits a RACH response
(referred to as a "Msg1 response") to the UE 604 with a C-RNTI via
a PDCCH associated with the SpCell. For example, the response may
comprise cyclic redundancy check (CRC) bits scrambled by the
C-RNTI. After the WWAN transceiver 310 of the UE 604 processes the
received response with the C-RNTI via the SpCell PDCCH from the
base station 602 and determines that the received PDCCH is
addressed to the C-RNTI, the processing system 332 determines that
the beam failure recovery procedure has completed and stops the BFR
timer started at 625. In an aspect, the C-RNTI may be mapped to a
beam direction determined by the base station 602 to be the best
direction for an uplink channel (e.g., PUCCH) for the UE 604.
Accordingly, upon receipt of the response with C-RNTI from the base
station 602, the UE 604 may be able to determine the optimal uplink
transmit beam that is best suited for the uplink channel.
[0130] The operations at 630 are part of a first scenario in which
the UE 604 successfully recovers from the beam failure detected at
615. However, such a recovery may not always occur, or at least not
before the BFR timer started at 625 times out. If the BFR timer
expires before the beam failure recovery procedure completes
successfully, then at 635, the UE 604 determines that a radio link
failure (RLF) has occurred.
[0131] FIG. 7 illustrates an exemplary wireless communications
system 700 according to various aspects of the disclosure. In the
example of FIG. 7, a UE 704, which may correspond to any of the UEs
described herein, is attempting to calculate an estimate of its
position, or assist another entity (e.g., a base station or core
network component, another UE, a location server, a third party
application, etc.) to calculate an estimate of its position. The UE
704 may communicate wirelessly with a plurality of base stations
702-1, 702-2, and 702-3 (collectively, base stations 702), which
may correspond to any combination of the base stations described
herein, using RF signals and standardized protocols for the
modulation of the RF signals and the exchange of information
packets. By extracting different types of information from the
exchanged RF signals, and utilizing the layout of the wireless
communications system 700 (e.g., the base stations locations,
geometry, etc.), the UE 704 may determine its position, or assist
in the determination of its position, in a predefined reference
coordinate system. In an aspect, the UE 704 may specify its
position using a two-dimensional (2D) coordinate system; however,
the aspects disclosed herein are not so limited, and may also be
applicable to determining positions using a three-dimensional (3D)
coordinate system, if the extra dimension is desired. Additionally,
while FIG. 7 illustrates one UE 704 and three base stations 702, as
will be appreciated, there may be more UEs 704 and more or fewer
base stations 702.
[0132] To support position estimates, the base stations 702 may be
configured to broadcast positioning reference signals (e.g., PRS,
NRS, TRS, CRS, etc.) to UEs 704 in their coverage area to enable a
UE 704 to measure characteristics of such reference signals. For
example, the OTDOA positioning method, also referred to as the time
difference of arrival (TDOA) positioning method, is a
multilateration method in which the UE 704 measures the time
difference, known as a RSTD, between specific reference signals
(e.g., PRS, NRS, TRS, CRS, etc.) transmitted by different pairs of
network nodes (e.g., base stations 702, antennas of base stations
702, etc.) and either reports these time differences to a location
server, such as the location server 230 or LMF 270, or computes a
location estimate itself from these time differences.
[0133] Generally, RSTDs are measured between a reference network
node (e.g., base station 702-1 in the example of FIG. 7) and one or
more neighbor network nodes (e.g., base stations 702-2 and 702-3 in
the example of FIG. 7). The reference network node remains the same
for all RSTDs measured by the UE 704 for any single positioning use
of OTDOA and would typically correspond to the serving cell for the
UE 704 or another nearby cell with good signal strength at the UE
704. In an aspect, where a measured network node is a cell
supported by a base station, the neighbor network nodes would
normally be cells supported by base stations different from the
base station for the reference cell and may have good or poor
signal strength at the UE 704. The location computation can be
based on the measured time differences (e.g., RSTDs) and knowledge
of the network nodes' locations and relative transmission timing
(e.g., regarding whether network nodes are accurately synchronized
or whether each network node transmits with some known time
difference relative to other network nodes).
[0134] To assist positioning operations, a location server (e.g.,
location server 230, LMF 270) may provide OTDOA assistance data to
the UE 704 for the reference network node (e.g., base station 702-1
in the example of FIG. 7) and the neighbor network nodes (e.g.,
base stations 702-2 and 702-3 in the example of FIG. 7) relative to
the reference network node. For example, the assistance data may
provide the center channel frequency of each network node, various
reference signal configuration parameters (e.g., the number of
consecutive positioning subframes, periodicity of positioning
subframes, muting sequence, frequency hopping sequence, reference
signal identifier (ID), reference signal bandwidth), a network node
global ID, and/or other cell related parameters applicable to
OTDOA. The OTDOA assistance data may indicate the serving cell for
the UE 704 as the reference network node.
[0135] In some cases, OTDOA assistance data may also include
"expected RSTD" parameters, which provide the UE 704 with
information about the RSTD values the UE 704 is expected to measure
at its current location between the reference network node and each
neighbor network node, together with an uncertainty of the expected
RSTD parameter. The expected RSTD, together with the associated
uncertainty, may define a search window for the UE 704 within which
the UE 704 is expected to measure the RSTD value. OTDOA assistance
information may also include reference signal configuration
information parameters, which allow a UE 704 to determine when a
reference signal positioning occasion occurs on signals received
from various neighbor network nodes relative to reference signal
positioning occasions for the reference network node, and to
determine the reference signal sequence transmitted from various
network nodes in order to measure a signal time of arrival (ToA) or
RSTD.
[0136] In an aspect, while the location server (e.g., location
server 230, LMF 270) may send the assistance data to the UE 704,
alternatively, the assistance data can originate directly from the
network nodes (e.g., base stations 702) themselves (e.g., in
periodically broadcasted overhead messages, etc.). Alternatively,
the UE 704 can detect neighbor network nodes itself without the use
of assistance data.
[0137] The UE 704 (e.g., based in part on the assistance data, if
provided) can measure and (optionally) report the RSTDs between
reference signals received from pairs of network nodes. Using the
RSTD measurements, the known absolute or relative transmission
timing of each network node, and the known position(s) of the
transmitting antennas for the reference and neighboring network
nodes, the network (e.g., location server 230/LMF 270, a base
station 702) or the UE 704 may estimate a position of the UE 704.
More particularly, the RSTD for a neighbor network node "k"
relative to a reference network node "Ref" may be given as
(ToA.sub.k-ToA.sub.Ref), where the ToA values may be measured
modulo one subframe duration (1 ms) to remove the effects of
measuring different subframes at different times. In the example of
FIG. 7, the measured time differences between the reference cell of
base station 702-1 and the cells of neighboring base stations 702-2
and 702-3 are represented as t.sub.2-t.sub.1 and t.sub.3-t.sub.1,
where t.sub.1, t.sub.2, and t.sub.3 represent the ToA of a
reference signal from the transmitting antenna(s) of base stations
702-1, 702-2, and 702-3, respectively. The UE 704 may then convert
the ToA measurements for different network nodes to RSTD
measurements and (optionally) send them to the location server
230/LMF 270. Using (i) the RSTD measurements, (ii) the known
absolute or relative transmission timing of each network node,
(iii) the known position(s) of physical transmitting antennas for
the reference and neighboring network nodes, and/or (iv)
directional reference signal characteristics such as a direction of
transmission, the UE's 704 position may be determined (either by
the UE 704 or the location server 230/LMF 270).
[0138] Still referring to FIG. 7, when the UE 704 obtains a
location estimate using OTDOA measured time differences, the
necessary additional data (e.g., the network nodes' locations and
relative transmission timing) may be provided to the UE 704 by a
location server (e.g., location server 230, LMF 270). In some
implementations, a location estimate for the UE 704 may be obtained
(e.g., by the UE 704 itself or by the location server 230/LMF 270)
from OTDOA measured time differences and from other measurements
made by the UE 704 (e.g., measurements of signal timing from GPS or
other global navigation satellite system (GNSS) satellites). In
these implementations, known as hybrid positioning, the OTDOA
measurements may contribute towards obtaining the UE's 704 location
estimate but may not wholly determine the location estimate.
[0139] UTDOA is a similar positioning method to OTDOA, but is based
on uplink reference signals (e.g., SRS, uplink PRS) transmitted by
the UE (e.g., UE 704). Further, transmission and/or reception
beamforming at the base station 702 and/or UE 704 can enable
wideband bandwidth at the cell edge for increased precision. Beam
refinements may also leverage channel reciprocity procedures in 5G
NR.
[0140] Another uplink positioning procedure is UL-AOA. In UL-AoA
positioning, the base station uses the angle and other properties
(e.g., signal strength) of the uplink receive beam on which it
receives reference signals (e.g., SRS) to estimate the location of
the UE. The base station, or other positioning entity, may also use
the signal propagation time between the base station and the UE to
determine the distance between the base station and the UE to
further refine the location estimate of the UE. The signal
propagation time, or flight time, may be determined using
multi-RTT.
[0141] The term "position estimate" is used herein to refer to an
estimate of a position for a UE, which may be geographic (e.g., may
comprise a latitude, longitude, and possibly altitude) or civic
(e.g., may comprise a street address, building designation, or
precise point or area within or nearby to a building or street
address, such as a particular entrance to a building, a particular
room or suite in a building, or a landmark such as a town square).
A position estimate may also be referred to as a "location," a
"position," a "fix," a "position fix," a "location fix," a
"location estimate," a "fix estimate," or by some other term. The
means of obtaining a location estimate may be referred to
generically as "positioning," "locating," or "position fixing." A
particular solution for obtaining a position estimate may be
referred to as a "position solution." A particular method for
obtaining a position estimate as part of a position solution may be
referred to as a "position method" or as a "positioning
method."
[0142] As noted above, an "RF signal" comprises an electromagnetic
wave that transports information through the space between a
transmitter and a receiver. An RF signal typically suffers from
some amount of path loss, or path attenuation, which is the
reduction in power density (attenuation) of an electromagnetic wave
(the RF signal) as it propagates through space. Path loss may be
due to many effects, such as free-space loss, refraction,
diffraction, reflection, aperture-medium coupling loss, and
absorption. Path loss is also influenced by terrain contours,
environment (e.g., urban or rural, vegetation and foliage, etc.),
propagation medium (e.g., dry or moist air), the distance between
the transmitter and the receiver, and the height and location of
the transmit antenna(s).
[0143] A transmitter (e.g., a base station or a UE) may transmit a
single RF signal or multiple RF signals to a receiver (e.g., a UE
or a base station). However, the receiver may receive multiple RF
signals corresponding to each transmitted RF signal due to the
propagation characteristics of RF signals through multipath
channels. The same transmitted RF signal on different paths between
the transmitter and receiver may be referred to as a "multipath" RF
signal. Multipath RF signals combine at the receiver, resulting in
a received signal that may vary widely, depending on the
distribution of the intensity and relative propagation time of the
waves and bandwidth of the transmitted signal.
[0144] As noted above, during UTDOA positioning procedures (and
other uplink or uplink-plus-downlink positioning procedures, such
as multi-RTT and UL-AoA), a UE transmits uplink reference signals,
such as SRS and uplink PRS, that need to be transmitted with a high
enough transmit power that they can be measured by neighboring
cells. Because neighboring cells may be further away from the UE
than the serving cell, there may be more path loss between the UE
and the neighboring cell than between the UE and the serving cell.
As such, these uplink reference signals may need to be transmitted
with a higher transmit power than uplink signals transmitted to the
serving cell.
[0145] Several options have been identified for setting the
transmission power of uplink reference signals transmitted for
positioning purposes (e.g., UTDOA). As a first option, the transmit
power of such uplink reference signals may be constant (i.e., no
power control is supported). As a second option, the transmit power
of uplink reference signals may be based on the existing power
control procedure. As a third option, the transmit power may be
determined by modifying the existing power control procedure. For
example, a downlink reference signal of a neighboring cell can be
configured to be used for the path loss estimation for an uplink
reference signal. More specifically, the UE can estimate the path
loss of the downlink reference signal and determine the appropriate
transmit power for the uplink reference signal based on the
determined path loss. In an aspect, the downlink reference signals
may be a CSI-RS, an SSB, a downlink PRS, etc.
[0146] Referring to the third option, using a downlink reference
signal from a neighboring cell to estimate the path loss of an
uplink reference signal, various other features need to be
supported in 5G NR in addition to the existing legacy behaviour.
For example, there needs to be support for configuring a downlink
reference signal of a neighboring cell to be used as the downlink
path loss reference for the purposes of uplink reference signal
power control. However, there is no fall back procedure currently
specified if the UE is not able to obtain the path loss reference.
Accordingly, the present disclosure describes various fall back
procedures if the UE is not able to obtain the path loss
reference.
[0147] In addition to using a downlink reference signal to
determine the transmit power of an uplink reference signal, a UE
can use a downlink reference signal from a neighboring cell to
determine the spatial direction of an uplink transmit beam (also
referred to as spatial transmit QCL, spatial QCL, spatial transmit
beam, and the like) carrying uplink reference signals (again in the
case of a positioning procedure). The downlink reference signal to
determine the transmit power of an uplink reference signal and the
downlink reference signal to determine the spatial direction of an
uplink transmit beam may be, but need not be, the same downlink
reference signal. For uplink beam management/alignment towards the
serving and neighboring cells, various features (in addition to UE
transmit beam sweeping) are currently supported. First, the
configuration of a spatial relation between a downlink reference
signal from the serving cell or neighboring cell(s) and the target
uplink reference signal is supported. Downlink reference signals
that can be used include at least an SSB, and possibly CSI-RS and
PRS. Second, a fixed transmit beam for uplink reference signal
transmissions across multiple uplink reference signal resources,
for both FR1 and FR2, is supported. Note that currently, a UE is
not expected to transmit multiple uplink reference signal resources
with different spatial relations in the same OFDM symbol.
[0148] As noted above, the UE can calculate the transmit power for
an uplink reference signal based on the path loss of a downlink
reference signal. The UE can do so as follows. If a UE transmits
uplink reference signals (e.g., SRS) on uplink BWP b of carrier f
of serving cell c using an SRS power control adjustment state with
index l, the UE determines the SRS transmission power
P.sub.SRS,b,f,c(i,q.sub.s,l) in SRS transmission occasion i as (in
dBm):
P SRS , b , f , c ( i , q s , l ) = min { P CMAX , f , c ( i ) , P
O _ SRS , b , f , c ( q s ) + 10 log 10 ( 2 u .times. M SRS , b , f
, c ( i ) ) + a SRS , b , f , c ( q s ) .times. PL b , f , c ( q d
) + h b , f , c ( i , l ) } ##EQU00001##
where: [0149] P.sub.CMAX,f,c(i) is the configured UE transmit power
for carrier f of serving cell c in SRS transmission occasion i;
[0150] P.sub.O_SRS,b,f,c(q.sub.s) is provided by higher layer
parameter p0 for uplink BWP b of carrier f of serving cell c and
SRS resource set q.sub.s provided by higher layer parameters
SRS-ResourceSet and SRS-ResourceSetId. If p0 is not provided,
P.sub.O_SRS,b,f,c(q.sub.s)=P.sub.O_NOMINALPUSCH,f,c(0); [0151]
M.sub.SRS,b,f,c(i) is the SRS bandwidth expressed in number of
resource blocks for SRS transmission occasion i on active uplink
BWP b of carrier f of serving cell c and .mu. is a SCS
configuration; [0152] .alpha..sub.SRS,b,f,c(q.sub.s) is provided by
higher layer parameter alpha for uplink BWP b of carrier f of
serving cell c and SRS resource set q.sub.s; [0153]
PL.sub.b,f,c(q.sub.d) is a downlink path loss estimate in dB
calculated by the UE using reference signal index q.sub.d for a
downlink BWP that is linked with uplink BWP b of carrier f of
serving cell c and SRS resource set q.sub.s. The reference signal
index q.sub.d is provided by the higher layer parameter
pathlossReferenceRS associated with the SRS resource set q.sub.s
and is either a higher layer parameter ssb-Index providing an
SS/PBCH block index or a higher layer parameter csi-RS-Index
providing a CSI-RS resource index. If the UE is not provided the
higher layer parameter pathlossReferenceRS or before the UE is
provided dedicated higher layer parameters, the UE calculates
PL.sub.b,f,c(q.sub.d) using a reference signal resource obtained
from the SS/PBCH block index that the UE uses to obtain the MIB. If
the UE is provided pathlossReferenceLinking, the reference signal
resource is on a serving cell indicated by a value of
pathlossReferenceLinking; [0154] h.sub.b,f,c(i,l)=f.sub.b,f,c(i,l),
where f.sub.b,f,c(i,l) is the current PUSCH power control
adjustment state, if the higher layer parameter
srs-PowerControlAdjustmentStates indicates the same power control
adjustment state for SRS transmissions and PUSCH transmissions.
[0155] As noted above, a maximum of four BWPs can be specified in
the downlink and uplink. Currently, there may be up to four path
loss estimates per serving cell, one for each BWP. Specifically, a
UE does not expect to simultaneously maintain more than four path
loss estimates per serving cell for all PUSCH/PUCCH/SRS
transmissions. The pathlossReferenceLinking parameter indicates
whether the UE shall apply as path loss reference either the
downlink of the PCell or the SCell that corresponds with this
uplink.
[0156] As noted above, some wireless communications networks, such
as 5G NR, may employ mmW or near mmW frequencies to increase the
network capacity. The use of mmW frequencies may be in addition to
microwave frequencies (e.g., in the sub-6 GHz band) that may also
be supported for use in communication, e.g., when carrier
aggregation is used. Because communication at high mmW frequencies
utilizes directionality (e.g., communication via directional beams)
to compensate for higher propagation loss, a base station and a UE
may need to align their beams during both initial network access
(e.g., a random access procedure, as illustrated in FIGS. 5A and
5B) and subsequent data transmissions to ensure maximum gain. The
base station and the UE may determine the best beams for
communicating with each other, and the subsequent communications
between the base station and the UE may be via the selected beams.
However, due to UE mobility/movement, beam reconfiguration at the
base station, and/or other factors, a downlink beam (e.g.,
comprising a downlink control link), which may have been the
preferred active beam, may fail to be detected at the UE, or the
signal quality may fall below a threshold, causing the UE to
consider it as a beam/link failure.
[0157] A beam recovery procedure (e.g., as illustrated in FIG. 6)
may be employed to recover from a beam failure. A beam failure may
refer to, for example, failure to detect a strong (e.g., with
signal power greater than a threshold) downlink transmit beam, a
failure to accurately (e.g., based on a signal strength threshold)
measure the path loss of a reference signal, or the like. The
recovery process may include the UE performing a random access
procedure (e.g., as illustrated in FIGS. 5A and 5B) to request a
new beam assignment. Specifically, the UE may indicate a new SSB or
CSI-RS for a new transmit beam during the random access procedure.
The base station assigns a new beam based on the beam failure
recovery request from the UE by transmitting a downlink assignment
or uplink grant on the PDCCH. Subsequently, a new beam pair (i.e.,
transmit/receive beam pair) can be established.
[0158] Performing a path loss estimation or spatial transmit beam
determination (also referred to as spatial transmit QCL
determination) on a downlink reference signal from a neighboring
(non-serving) cell may be a difficult task since the neighboring
cell may be far away. The path loss estimate is prone to errors,
and as a result, the transmit power or spatial transmit
determination made by the UE may be prone to errors. As such, there
are various issues that need to be addressed, such as how the UE
should inform the location server (e.g., location server 230, LMF
270) that the path loss reference signal or spatial transmit beam
reference signal is failing, how the UE should transmit the uplink
reference signal resources while the downlink reference signals are
failing, and the procedure to avoid the failure of the path loss or
spatial transmit estimation for neighboring cells.
[0159] When the UE is configured to perform path loss estimation or
a spatial transmit QCL determination using a downlink reference
signal from a neighboring cell, and the UE identifies that the
reference signal cannot be used for this purpose, there are several
options as to how the UE can inform the location server that the
reference signal is failing. As a first option, the UE can inform
the serving base station (which then informs the location server)
through, for example, RRC signaling, or the UE can inform the
location server directly through higher layer signaling (e.g., LTE
positioning protocol (LPP)) that the path loss downlink reference
signal or spatial transmit QCL downlink reference signal for a
specific uplink reference signal resource is failing. As a second
option, the UE can request to be configured with an alternative
and/or a secondary downlink reference signal from the serving cell
to replace the affected uplink reference signal resource(s). As a
third option, the UE can request to be configured with an
alternative and/or a secondary downlink reference signal from the
neighboring cell(s) to replace the affected uplink reference signal
resource(s).
[0160] Being configured with an alternative downlink reference
signal means that the UE may have been configured with multiple
downlink reference signals and may choose one of them. Being
configured with a secondary downlink reference signal means that
the UE is configured with a primary downlink reference signal, but
can use the secondary downlink reference signal if the primary
downlink reference signal fails. The first three options are
complementary, insofar as the UE may report that the downlink
reference signal has failed (first option) and request a
replacement (second and third options).
[0161] As a fourth option, the UE can start a random access
procedure with the serving cell, as in the case of a beam failure
recovery procedure, but with a preamble sequence number that
indicates that the neighboring cell's downlink transmit beam has
failed, rather than a downlink transmit beam from the serving cell.
Based on the sequence number, the serving cell can then inform the
location server or the neighboring cell(s) through a higher layer
protocol (e.g., the Xn interface) of the beam failure. As a fifth
option, the UE can start a partial beam failure recovery procedure,
meaning that the UE may report that a subset (more than one) of the
neighboring downlink reference signals has failed. This report may
be through the regular PUCCH/PUSCH channel, rather than the PRACH,
as in the fourth option. The serving cell can then inform the
location server or the neighboring cell(s) of the failure through a
higher layer protocol (e.g., the Xn interface).
[0162] Another issue is how the UE should transmit the uplink
reference signal resources while the downlink reference signals are
failing. When the UE is configured to perform path loss estimation
using a downlink reference signal from a neighboring cell, and the
UE identifies that the reference signal cannot be used for this
purpose, there are various options the UE can follow. If the
downlink reference signal is being used for a path loss reference,
then as a first option, the UE can transmit the uplink reference
signal at its maximum transmit power until a new downlink reference
signal is configured for path loss estimation. The UE may transmit
at its maximum transmit power under the assumption that if it can
no longer detect the downlink reference signal from the neighboring
cell, it is because the neighboring cell is far away. As a second
option, the UE can use a configured secondary downlink reference
signal (as requested above) from the serving cell or a neighboring
cell to assist with the path loss estimation. As a third option,
the UE can use the path loss downlink reference signal configured
for the uplink reference signal of the serving cell (or of the
PUSCH/PUCCH). As a fourth option, the UE can use a default downlink
transmit beam (i.e., the same downlink transmit beam) for both the
path loss reference signal and the spatial QCL reference signal.
For example, the UE could use the transmit beam with the lowest
uplink reference signal resource ID.
[0163] If the downlink reference signal is being used for a spatial
QCL reference, then as a first option, the UE can use a configured
secondary downlink reference signal from the serving cell to assist
with the derivation of the uplink transmit beam (spatial QCL). As a
second option, if the UE has been configured with multiple downlink
reference signals from a specific neighboring cell, the UE can
transmit the effected resource with one of the uplink transmit
beams derived from the other downlink reference signals of the same
neighboring cell. As a third option, if the UE has only been
configured with one downlink reference signal from the neighboring
cell, the UE can transmit the effected resource with an uplink
transmit beam derived from a downlink reference signal of the
serving cell. As a fourth option, the UE can use a default downlink
transmit beam (i.e., the same downlink transmit beam) for both the
path loss downlink reference signal and the spatial QCL downlink
reference signal. For example, the UE could use the transmit beam
with the lowest uplink reference signal resource ID.
[0164] As will be appreciated, other than using the maximum
transmit power in the case of a failed downlink reference signal
being used for a path loss reference, the options for both path
loss and spatial QCL uplink reference signals are similar.
[0165] Referring now to the procedure to avoid the failure of the
path loss/spatial transmit QCL estimation downlink reference
signals from neighboring cells, there are several steps that can be
taken. First, the location server can configure the UE with
downlink reference signals from neighboring cells to perform the
path loss or spatial transmit beam determination. Second, the UE
can periodically report the RSRP, RSRQ, and/or SINR of any downlink
reference signals from neighboring cells that are being used for
path loss or spatial transmit QCL estimation of uplink reference
signal transmissions. Alternatively, the location server can
configure for which downlink reference signals such reporting would
be helpful. This may be accomplished through direct reporting to
the location server or reporting to the base station, which then
relays the report to either neighboring base stations (e.g., via
the Xn interface) or to the location server (e.g., location server
230, LMF 270). Third, when the RSRP/RSRQ/SINR is low, the location
server can proactively reconfigure the downlink reference
signals.
[0166] An RSRP/RSRQ/SINR threshold can be used to decide whether
the current downlink reference signal can be used for path loss
reference estimation or spatial QCL determination.
[0167] FIG. 8 illustrates an exemplary method 800 of wireless
communication, according to aspects of the disclosure. In an
aspect, the method 800 may be performed by a UE (e.g., any of the
UEs described herein).
[0168] At 810, the UE receives a positioning configuration (e.g.,
via RRC, LPP, and/or other signaling from a location server,
serving cell, or other such entity), the positioning configuration
including at least an identifier of a first downlink reference
signal from a neighboring cell to be used for estimating a downlink
path loss or determining an uplink spatial transmit beam. In an
aspect, operation 810 may be performed by WWAN transceiver 310,
processing system 332, memory component 340, and/or positioning
component 342, and or all of which may be considered means for
performing this operation.
[0169] At 820, the UE determines whether or not the first downlink
reference signal received from the neighboring cell has failed. In
an aspect, operation 820 may be performed by WWAN transceiver 310,
processing system 332, memory component 340, and/or positioning
component 342, and or all of which may be considered means for
performing this operation.
[0170] At 830, in response to determining that the first downlink
reference signal has failed, the UE estimates the downlink path
loss or determines the uplink spatial transmit beam based on a
second downlink reference signal received from the neighboring cell
or a serving cell for the UE. In an aspect, operation 830 may be
performed by WWAN transceiver 310, processing system 332, memory
component 340, and/or positioning component 342, and or all of
which may be considered means for performing this operation.
[0171] At 840, the UE transmits an uplink reference signal for
positioning based on the estimated downlink path loss, the
determined uplink spatial transmit beam, or a combination thereof.
In an aspect, operation 840 may be performed by WWAN transceiver
310, processing system 332, memory component 340, and/or
positioning component 342, and or all of which may be considered
means for performing this operation.
[0172] FIG. 9 illustrates an exemplary method 900 of wireless
communication, according to aspects of the disclosure. In an
aspect, method 900 may be performed by a location server (e.g.,
location server 230, LMF 270).
[0173] At 910, the location server configures (e.g., via LPP) a UE
(e.g., any of the UEs described herein) to receive at least a first
downlink reference signal from a neighboring cell to be used to
estimate a downlink path loss or determine an uplink spatial
transmit beam. In an aspect, operation 910 may be performed by
network interface(s) 390, processing system 394, memory component
396, and/or positioning component 398, and or all of which may be
considered means for performing this operation.
[0174] At 920, the location server receives, from the UE, a report
indicating a signal quality of the first downlink reference signal.
In an aspect, operation 920 may be performed by network
interface(s) 390, processing system 394, memory component 396,
and/or positioning component 398, and or all of which may be
considered means for performing this operation.
[0175] At 930, based on the signal quality of the first downlink
reference signal being below a threshold, the location server
configures the UE to receive at least a second downlink reference
signal from the neighboring cell or a serving cell to be used to
estimate the downlink path loss or determine the uplink spatial
transmit beam. In an aspect, operation 930 may be performed by
network interface(s) 390, processing system 394, memory component
396, and/or positioning component 398, and or all of which may be
considered means for performing this operation.
[0176] FIG. 10 illustrates an exemplary method 1000 of wireless
communication, according to aspects of the disclosure. In an
aspect, the method 1000 may be performed by a UE (e.g., any of the
UEs described herein).
[0177] At 1010, the UE receives, from a network node (e.g., a
serving base station or a location server), a configuration (e.g.,
via RRC, LPP, and/or other signaling from a location server,
serving cell, or other such entity) to use at least a first
downlink reference signal from a neighboring cell to estimate
downlink path loss or determine an uplink spatial transmit beam. In
an aspect, operation 1010 may be performed by WWAN transceiver 310,
processing system 332, memory component 340, and/or positioning
component 342, and or all of which may be considered means for
performing this operation.
[0178] At 1020, the UE sends, to the network node, a report
indicating a signal quality of the first downlink reference signal.
In an aspect, operation 1020 may be performed by WWAN transceiver
310, processing system 332, memory component 340, and/or
positioning component 342, and or all of which may be considered
means for performing this operation.
[0179] At 1030, based on the signal quality of the first downlink
reference signal being below a threshold, the UE receives, from the
network node, a configuration (e.g., via RRC, LPP, and/or other
signaling from a location server, serving cell, or other such
entity) to use at least a second downlink reference signal from the
neighboring cell or a serving cell to estimate the downlink path
loss or determine the uplink spatial transmit beam. In an aspect,
operation 1030 may be performed by WWAN transceiver 310, processing
system 332, memory component 340, and/or positioning component 342,
and or all of which may be considered means for performing this
operation.
[0180] Those of skill in the art will appreciate that information
and signals may be represented using any of a variety of different
technologies and techniques. For example, data, instructions,
commands, information, signals, bits, symbols, and chips that may
be referenced throughout the above description may be represented
by voltages, currents, electromagnetic waves, magnetic fields or
particles, optical fields or particles, or any combination
thereof.
[0181] Further, those of skill in the art will appreciate that the
various illustrative logical blocks, modules, circuits, and
algorithm steps described in connection with the aspects disclosed
herein may be implemented as electronic hardware, computer
software, or combinations of both. To clearly illustrate this
interchangeability of hardware and software, various illustrative
components, blocks, modules, circuits, and steps have been
described above generally in terms of their functionality. Whether
such functionality is implemented as hardware or software depends
upon the particular application and design constraints imposed on
the overall system. Skilled artisans may implement the described
functionality in varying ways for each particular application, but
such implementation decisions should not be interpreted as causing
a departure from the scope of the present disclosure.
[0182] The various illustrative logical blocks, modules, and
circuits described in connection with the aspects disclosed herein
may be implemented or performed with a general purpose processor, a
DSP, an ASIC, an FPGA, or other programmable logic device, 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 conventional 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.
[0183] The methods, sequences and/or algorithms described in
connection with the aspects disclosed herein may be embodied
directly in hardware, in a software module executed by a processor,
or in a combination of the two. A software module may reside in
random access memory (RAM), flash memory, read-only memory (ROM),
erasable programmable ROM (EPROM), electrically erasable
programmable ROM (EEPROM), registers, hard disk, a removable disk,
a CD-ROM, or any other form of storage medium known in the art. An
exemplary storage medium is coupled to the 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. The processor and the storage medium may
reside in an ASIC. The ASIC may reside in a user terminal (e.g.,
UE). In the alternative, the processor and the storage medium may
reside as discrete components in a user terminal.
[0184] In one or more exemplary aspects, the functions described
may be implemented in hardware, software, firmware, or any
combination thereof. If implemented in software, the functions may
be stored on or transmitted over as one or more instructions or
code on a computer-readable medium. Computer-readable media
includes both computer storage media and communication media
including any medium that facilitates transfer of a computer
program from one place to another. A storage media may be any
available media that can be accessed by a computer. By way of
example, and not limitation, such computer-readable media can
comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage,
magnetic disk storage or other magnetic storage devices, or any
other medium that can be used to carry or store desired program
code in the form of instructions or data structures and that can be
accessed by a computer. 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, 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, includes compact disc (CD), laser disc, optical
disc, digital versatile disc (DVD), floppy disk and Blu-ray disc
where disks usually reproduce data magnetically, while discs
reproduce data optically with lasers. Combinations of the above
should also be included within the scope of computer-readable
media.
[0185] While the foregoing disclosure shows illustrative aspects of
the disclosure, it should be noted that various changes and
modifications could be made herein without departing from the scope
of the disclosure as defined by the appended claims. The functions,
steps and/or actions of the method claims in accordance with the
aspects of the disclosure described herein need not be performed in
any particular order. Furthermore, although elements of the
disclosure may be described or claimed in the singular, the plural
is contemplated unless limitation to the singular is explicitly
stated.
* * * * *