U.S. patent application number 14/525185 was filed with the patent office on 2015-04-30 for systems and methods for improved communication efficiency in high efficiency wireless networks.
The applicant listed for this patent is QUALCOMM Incorporated. Invention is credited to Andrea Garavaglia, Simone Merlin, Ahmed Kamel Sadek, Andreas Maximilian Schenk, Patrick Stupar, Marc Walter Werner.
Application Number | 20150117366 14/525185 |
Document ID | / |
Family ID | 52995374 |
Filed Date | 2015-04-30 |
United States Patent
Application |
20150117366 |
Kind Code |
A1 |
Stupar; Patrick ; et
al. |
April 30, 2015 |
SYSTEMS AND METHODS FOR IMPROVED COMMUNICATION EFFICIENCY IN HIGH
EFFICIENCY WIRELESS NETWORKS
Abstract
Methods and apparatus for adjusting transmission power in
wireless networks are provided. One aspect of the disclosure
provides a method of wireless communication over a wireless
communication medium. The method includes determining a level of
interference for a data transmission from a transmitting device to
an intended receiving device. The method further includes setting a
transmission power level for transmitting a message based on the
interference level, the message comprising one of a request-to-send
(RTS) packet and a clear-to-send (CTS) packet. The method further
includes transmitting the message at the set transmission power
level.
Inventors: |
Stupar; Patrick; (Nuremberg,
DE) ; Sadek; Ahmed Kamel; (San Diego, CA) ;
Garavaglia; Andrea; (Nuremberg, DE) ; Werner; Marc
Walter; (Heroldsberg, DE) ; Schenk; Andreas
Maximilian; (Erlangen, DE) ; Merlin; Simone;
(Solana Beach, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM Incorporated |
San Diego |
CA |
US |
|
|
Family ID: |
52995374 |
Appl. No.: |
14/525185 |
Filed: |
October 27, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61897135 |
Oct 29, 2013 |
|
|
|
61924156 |
Jan 6, 2014 |
|
|
|
61928845 |
Jan 17, 2014 |
|
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Current U.S.
Class: |
370/329 |
Current CPC
Class: |
H04W 84/12 20130101;
H04L 47/828 20130101; H04L 5/0078 20130101; H04W 72/0473 20130101;
H04W 72/082 20130101; H04W 52/243 20130101; H04L 5/00 20130101;
H04L 27/0006 20130101; H04L 47/826 20130101; H04W 24/10 20130101;
H04W 74/04 20130101 |
Class at
Publication: |
370/329 |
International
Class: |
H04W 52/24 20060101
H04W052/24; H04W 72/08 20060101 H04W072/08; H04W 72/04 20060101
H04W072/04; H04W 24/10 20060101 H04W024/10 |
Claims
1. A method of wireless communication over a wireless communication
medium comprising: determining a level of interference for a data
transmission from a transmitting device to an intended receiving
device; setting a transmission power level for transmitting a
message based on the interference level, the message comprising one
of a request-to-send (RTS) packet and a clear-to-send (CTS) packet;
and transmitting the message at the set transmission power
level.
2. The method of claim 1, wherein the transmitting device and the
receiving device each comprises one of an access point and a
station.
3. The method of claim 1, wherein the level of interference is
based on at least a packet error rate (PER) of the data
transmission from the transmitting device to the intended receiving
device.
4. The method of claim 1, further comprising: identifying one or
more potentially interfering devices detected by the transmitting
device; ordering the potentially interfering devices based on an
estimated transmit power level from the transmitting device to
reach each of the potentially interfering devices, wherein the
ordering identifies from a lowest estimated transmit power to a
highest estimated transmit power level; and setting the
transmission power level for transmitting the message based further
on the ordering of the estimated transmit power levels for the
potentially interfering devices.
5. The method of claim 4, wherein the setting of the transmission
power level of the message comprises: selecting a smallest
estimated power level from the lowest to the highest estimated
power levels in the ordering such that a new interference level
based on the data transmission at the selected smallest transmit
power level satisfies a threshold value.
6. The method of claim 4, wherein the setting of the transmission
power level of the message comprises: selecting a smallest
estimated power level from the lowest to the highest estimated
power levels in the ordering for a first transmission of the
message from the transmitting device to the receiving device;
transmitting the first transmission at the selected smallest
transmit power level; determining an interference level for the
first transmission; selecting a next highest estimated power level
from the lowest to the highest estimated power levels for a second
transmission of the message if the interference level for the first
transmission is greater than the threshold; transmitting the second
transmission at the selected next highest estimated transmit power
level; determining an interference level for the second
transmission; selecting a next highest estimated power level from
the lowest to the highest estimated power levels for a third
transmission of the message if the interference level of the second
transmission is greater than the threshold; and setting the
transmission power level of the message to selected estimated power
level if an interference level of one of the data transmissions is
less than the threshold.
7. The method of claim 4, wherein identifying the one or more
potentially interfering devices comprises: scanning for neighboring
basic service sets (BSSs); transmitting a querying message from the
transmitting device to the intended receiving device of the data
transmission; and identifying devices included in a neighboring BSS
from the scanned list of neighboring BSSs, but not detected by the
intended receiving device of the data transmission, as potentially
interfering devices.
8. The method of claim 6, wherein scanning for neighboring BSSs
comprises receiving beacons from potentially interfering devices,
wherein the estimated transmit power level is based on a transmit
power control (TPC) information element (IE) included in the
received beacons.
9. The method of claim 6, further comprising receiving a query
response message from the intended receiving device identifying a
list of devices detected by the intended receiving device as
potentially interfering devices for the data transmission from the
transmitting device to the intended receiving device.
10. The method of claim 8, wherein identifying devices included in
a neighboring BSS from the scanned list of neighboring BSSs, but
not detected by the intended receiving device of the data
transmission, as potentially interfering devices comprises
comparing the potentially interfering devices detected by the
transmitting device with the potentially interfering devices
detected by the intended receiving device.
11. The method of claim 4, wherein the estimated transmit power
level is based on a transmit power control (TPC) information
element (IE) included in a beacon received from potentially
interfering devices.
12. The method of claim 4, wherein identifying potentially
interfering devices detected by the transmitting device comprises
identifying devices transmitting acknowledgement (ACK) messages
that may potentially interfere with the data transmission from the
transmitting device to the intended receiving device.
13. An apparatus configured to perform wireless communication over
a wireless communication medium comprising: a processor configured
to: determine a level of interference for a data transmission to an
intended receiving device; and set a transmission power level for
transmitting a message based on the interference level, the message
comprising one of a request-to-send (RTS) packet and a
clear-to-send (CTS) packet; and a transmitter configured to
transmit the message at the set transmission power level.
14. The apparatus of claim 13, wherein the wherein the receiving
device comprises one of an access point and a station.
15. The apparatus of claim 13, wherein the level of interference is
based on at least a packet error rate (PER) of the data
transmission to the intended receiving device.
16. The apparatus of claim 13, wherein the processor is further
configured to: identify one or more potentially interfering devices
detected by the processor; order the potentially interfering
devices based on an estimated transmit power level from the
transmitting device to reach each of the potentially interfering
devices, wherein the ordering identifies from a lowest estimated
transmit power to a highest estimated transmit power level; and set
the transmission power level for transmitting the message based
further on the ordering of the estimated transmit power levels for
the potentially interfering devices.
17. The apparatus of claim 16, wherein the processor is further
configured to select a smallest estimated power level from the
lowest to the highest estimated power levels in the ordering such
that a new interference level based on the data transmission at the
selected smallest transmit power level satisfies a threshold
value.
18. The apparatus of claim 16, further comprising a receiver
configured to scan for neighboring basic service sets (BSSs),
wherein: the transmitter is further configured to transmit a
querying message to the intended receiving device of the data
transmission; and the processor is further configured to identify
devices included in a neighboring BSS from the scanned list of
neighboring BSSs, but not detected by the intended receiving device
of the data transmission, as potentially interfering devices.
19. The apparatus of claim 16, further comprising a receiver
configured to receive beacons from the potentially interfering
devices, wherein the estimated transmit power level is based on a
transmit power control (TPC) information element (IE) included in
the beacons.
20. The apparatus of claim 16, wherein the processor is further
configured to identify devices producing acknowledgement (ACK)
interference.
21. An apparatus for wireless communication over a wireless
communication medium comprising: means for determining a level of
interference for a data transmission to an intended receiving
device; means for setting a transmission power level for
transmitting a message based on the interference level, the message
comprising one of a request-to-send (RTS) packet and a
clear-to-send (CTS) packet; and means for transmitting the message
at the set transmission power level.
22. The apparatus of claim 21, wherein the level of interference is
based on at least a packet error rate (PER) of the data
transmission from the transmitting device to the intended receiving
device.
23. The apparatus of claim 21, further comprising: means for
identifying one or more potentially interfering devices; means for
ordering the potentially interfering devices based on an estimated
transmit power level from the transmitting means to reach each of
the potentially interfering devices, wherein the ordering means
identifies from a lowest estimated transmit power to a highest
estimated transmit power level; and means for setting the
transmission power level for transmitting the message based further
on the ordering of the estimated transmit power levels for the
potentially interfering devices.
24. The apparatus of claim 23, wherein means for setting the
transmission power of the message reserving the wireless medium
comprises means for selecting a smallest estimated power level from
the lowest to the highest estimated power levels in the ordering
such that a new interference level based on the selected smallest
transmit power level satisfies a threshold value.
25. The apparatus of claim 23, wherein means for identifying the
one or more potentially interfering devices comprises: means for
scanning for neighboring basic service sets (BSSs); transmitting a
querying message to the intended receiving device of the data
transmission; and means for identifying devices included in a
neighboring BSS from the scanned list of neighboring BSSs, but not
detected by the intended receiving device of the data transmission,
as potentially interfering devices.
26. The apparatus of claim 23, wherein means for identifying
potentially interfering devices comprises identifying devices
producing acknowledgement (ACK) interference.
27. A non-transitory computer-readable medium comprising code that,
when executed, causes an apparatus to: determine a level of
interference for a data transmission from a transmitting device to
an intended receiving device; set a transmission power level for
transmitting a message based on the interference level, the message
comprising one of a request-to-send (RTS) packet and a
clear-to-send (CTS) packet; and transmit the message the message at
the set transmission power level.
28. The medium of claim 27, further comprising code that, when
executed, causes the apparatus to: identify one or more potentially
interfering devices; order the potentially interfering devices
based on an estimated transmit power level from the transmitting
device to reach each of the potentially interfering devices,
wherein the ordering identifies from a lowest estimated transmit
power to a highest estimated transmit power level; and set the
transmission power level for transmitting the message based further
on the ordering of the estimated transmit power levels for the
potentially interfering devices.
29. The medium of claim 28, wherein setting the transmission power
of the message reserving the wireless medium comprises: selecting a
smallest estimated power level from the lowest to the highest
estimated power levels in the ordering such that a new interference
level based on the selected smallest transmit power level satisfies
a threshold value.
30. The medium of claim 28, wherein identifying the one or more
potentially interfering devices comprises: scanning for neighboring
basic service sets (BSSs); transmitting a querying message from the
transmitting device to the intended receiving device of the data
transmission; and identifying devices included in a neighboring BSS
from the scanned list of neighboring BSSs, but not detected by the
intended receiving device of the data transmission, as potentially
interfering devices.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C.
.sctn.119(e) to U.S. Provisional Patent Application No. 61/897,135
entitled "SYSTEMS AND METHODS FOR IMPROVED COMMUNICATION EFFICIENCY
IN HIGH EFFICIENCY WIRELESS NETWORKS" filed on Oct. 29, 2013 the
disclosure of which is hereby incorporated by reference in its
entirety. This application further claims priority under 35 U.S.C.
.sctn.119(e) to U.S. Provisional Patent Application No. 61/924,156,
entitled "SYSTEMS AND METHODS FOR IMPROVED COMMUNICATION EFFICIENCY
IN HIGH EFFICIENCY WIRELESS NETWORKS," filed Jan. 6, 2014, assigned
to the assignee hereof and incorporated herein by reference in its
entirety. This application further claims priority under 35 U.S.C.
.sctn.119(e) to U.S. Provisional Patent Application No. 61/928,845,
entitled "SYSTEMS AND METHODS FOR IMPROVED COMMUNICATION EFFICIENCY
IN HIGH EFFICIENCY WIRELESS NETWORKS," filed Jan. 17, 2014,
assigned to the assignee hereof and incorporated herein by
reference in its entirety.
FIELD
[0002] Certain aspects of the present disclosure generally relate
to wireless communications, and more particularly, to methods and
apparatus for adjusting transmission power in wireless
networks.
BACKGROUND
[0003] In many telecommunication systems, communications networks
are used to exchange messages among several interacting
spatially-separated devices. Networks can be classified according
to geographic scope, which could be, for example, a metropolitan
area, a local area, or a personal area. Such networks can be
designated respectively as a wide area network (WAN), metropolitan
area network (MAN), local area network (LAN), or personal area
network (PAN). Networks also differ according to the
switching/routing technique used to interconnect the various
network nodes and devices (e.g., circuit switching vs. packet
switching), the type of physical media employed for transmission
(e.g., wired vs. wireless), and the set of communication protocols
used (e.g., Internet protocol suite, SONET (Synchronous Optical
Networking), Ethernet, etc.).
[0004] Wireless networks are often preferred when the network
elements are mobile and thus have dynamic connectivity needs, or if
the network architecture is formed in an ad hoc, rather than fixed,
topology. Wireless networks employ intangible physical media in an
unguided propagation mode using electromagnetic waves in the radio,
microwave, infra-red, optical, etc. frequency bands. Wireless
networks advantageously facilitate user mobility and rapid field
deployment when compared to fixed wired networks.
[0005] The devices in a wireless network can transmit/receive
information between each other. Device transmissions can interfere
with each other, and certain transmissions can selectively block
other transmissions. Where many devices share a communication
network, congestion and inefficient link usage can result. As such,
systems, methods, and non-transitory computer-readable media are
needed for improving communication efficiency in high efficiency
wireless networks.
SUMMARY
[0006] Various implementations of systems, methods and devices
within the scope of the appended claims each have several aspects,
no single one of which is solely responsible for the desirable
attributes described herein. Without limiting the scope of the
appended claims, some prominent features are described herein.
[0007] Details of one or more implementations of the subject matter
described in this specification are set forth in the accompanying
drawings and the description below. Other features, aspects, and
advantages will become apparent from the description, the drawings,
and the claims. Note that the relative dimensions of the following
figures may not be drawn to scale.
[0008] One aspect of the disclosure provides a method of wireless
communication over a wireless communication medium. The method
includes determining a level of interference for a data
transmission from a transmitting device to an intended receiving
device. The method further includes setting a transmission power
level for transmitting a message based on the interference level,
the message comprising one of a request-to-send (RTS) packet and a
clear-to-send (CTS) packet. The method further includes
transmitting the message at the set transmission power level.
[0009] In various embodiments, the message reserving the wireless
medium can include one of a request-to-send (RTS) packet and a
clear-to-send (CTS) packet. In various embodiments, the
transmission metric can include a packet error rate (PER).
[0010] In various embodiments, the method can further include
identifying one or more potentially interfering devices. The method
can further include ordering the potentially interfering devices
based on an estimated transmit power to reach each potentially
interfering device. The method can further include setting the
transmission power for the message reserving the wireless medium
further based on the ordering.
[0011] In various embodiments, setting the transmission power of
the message reserving the wireless medium can include selecting a
lowest estimated transmit power in the ordering, and selecting a
next highest estimated transmit power in the ordering when the
interference metric crosses a threshold value.
[0012] In various embodiments, identifying the one or more
potentially interfering devices can include scanning for
neighboring basic service sets (BSSs), transmitting a querying
message to an intended recipient of the data transmission, and
identifying devices included in a neighboring BSS, but not visible
to or detected by the intended recipient of the data transmission,
as potentially interfering devices.
[0013] In various embodiments, the estimated transmit power is
based on a transmit power control (TPC) information element (IE)
included in a beacon. In various embodiments, potentially
interfering devices comprise devices producing acknowledgement
(ACK) interference.
[0014] Another aspect provides an apparatus configured to perform
wireless communication over a wireless communication medium. The
apparatus includes a processor configured to determine a level of
interference for a data transmission to an intended receiving
device n. The processor is further configured to set a transmission
power, for a message based on the interference level. The apparatus
further includes a transmitter configured to transmit the message
at the set transmission power level.
[0015] In various embodiments, the message reserving the wireless
medium can include one of a request-to-send (RTS) packet and a
clear-to-send (CTS) packet. In various embodiments, the
transmission metric can include a packet error rate (PER).
[0016] In various embodiments, the processor can be further
configured to identify one or more potentially interfering devices.
The processor can be further configured to order the potentially
interfering devices based on an estimated transmit power to reach
each potentially interfering device. The processor can be further
configured to set the transmission power for the message reserving
the wireless medium further based on the ordering.
[0017] In various embodiments, the processor can be further
configured to select a lowest estimated transmit power in the
ordering. The processor can be further configured to select a next
highest estimated transmit power in the ordering when the
interference metric crosses a threshold value.
[0018] In various embodiments, the apparatus can further include a
receiver configured to scan for neighboring basic service sets
(BSSs). The transmitter can be further configured to transmit a
querying message to an intended recipient of the data transmission.
The processor can be further configured to identify devices
included in a neighboring BSS, but not visible to or detected by
the intended recipient of the data transmission, as potentially
interfering devices.
[0019] In various embodiments, the estimated transmit power is
based on a transmit power control (TPC) information element (IE)
included in a beacon. In various embodiments, potentially
interfering devices comprise devices producing acknowledgement
(ACK) interference.
[0020] Another aspect provides an apparatus for wireless
communication over a wireless communication medium. The apparatus
includes means for determining a level of interference for a data
transmission to an intended receiving device. The apparatus further
includes means for setting a transmission power level for
transmitting a message reserving the wireless medium, based on the
interference level, the message comprising one of a request-to-send
(RTS) packet and a clear-to-send (CTS) packet. The apparatus
further includes means for transmitting the message at the set
transmission power level.
[0021] In various embodiments, the message reserving the wireless
medium can include one of a request-to-send (RTS) packet and a
clear-to-send (CTS) packet. In various embodiments, the
transmission metric can include a packet error rate (PER).
[0022] In various embodiments, the apparatus can further include
means for identifying one or more potentially interfering devices.
The apparatus can further include means for ordering the
potentially interfering devices based on an estimated transmit
power to reach each potentially interfering device. The apparatus
can further include means for setting the transmission power for
the message reserving the wireless medium further based on the
ordering.
[0023] In various embodiments, means for setting the transmission
power of the message reserving the wireless medium can include
means for selecting a lowest estimated transmit power in the
ordering and means for selecting a next highest estimated transmit
power in the ordering when the interference metric crosses a
threshold value.
[0024] In various embodiments, means for identifying the one or
more potentially interfering devices can include means for scanning
for neighboring basic service sets (BSSs), means for transmitting a
querying message to an intended recipient of the data transmission,
and means for identifying devices included in a neighboring BSS,
but not visible to or detected by the intended recipient of the
data transmission, as potentially interfering devices.
[0025] In various embodiments, the estimated transmit power is
based on a transmit power control (TPC) information element (IE)
included in a beacon. In various embodiments, potentially
interfering devices comprise devices producing acknowledgement
(ACK) interference.
[0026] Another aspect provides a non-transitory computer-readable
medium. The medium includes code that, when executed, causes an
apparatus to determine a level of interference for a data
transmission from a transmitting device to an intended receiving
device. The medium further includes code that, when executed,
causes the apparatus to set a transmission power level for
transmitting a message reserving the wireless medium, based on the
interference level, the message comprising one of a request-to-send
(RTS) packet and a clear-to-send (CTS) packet. The medium further
includes code that, when executed, causes the apparatus to transmit
the message the message at the set transmission power level.
[0027] In various embodiments, the message reserving the wireless
medium can include one of a request-to-send (RTS) packet and a
clear-to-send (CTS) packet. In various embodiments, the
transmission metric can include a packet error rate (PER).
[0028] In various embodiments, the medium can further include code
that, when executed, causes the apparatus to identify one or more
potentially interfering devices. The medium can further include
code that, when executed, causes the apparatus to order the
potentially interfering devices based on an estimated transmit
power to reach each potentially interfering device. The medium can
further include code that, when executed, causes the apparatus to
set the transmission power for the message reserving the wireless
medium further based on the ordering.
[0029] In various embodiments, setting the transmission power of
the message reserving the wireless medium can include selecting a
lowest estimated transmit power in the ordering and selecting a
next highest estimated transmit power in the ordering when the
interference metric crosses a threshold value.
[0030] In various embodiments, identifying the one or more
potentially interfering devices can include scanning for
neighboring basic service sets (BSSs), transmitting a querying
message to an intended recipient of the data transmission, and
identifying devices included in a neighboring BSS, but not visible
to or detected by the intended recipient of the data transmission,
as potentially interfering devices.
[0031] In various embodiments, the estimated transmit power is
based on a transmit power control (TPC) information element (IE)
included in a beacon. In various embodiments, potentially
interfering devices comprise devices producing acknowledgement
(ACK) interference.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 illustrates an example of a wireless communication
system in which aspects of the present disclosure can be
employed.
[0033] FIG. 2 illustrates various components that can be utilized
in a wireless device that can be employed within the wireless
communication system of FIG. 1.
[0034] FIG. 3 is a diagram of an exemplary wireless communication
system.
[0035] FIG. 4 is a diagram of an exemplary RTS/CTS exchange.
[0036] FIG. 5 is a diagram of an exemplary RTS/CTS exchange.
[0037] FIG. 6 is a time sequence diagram of the RTS/CTS
exchange
[0038] FIG. 7 is a diagram of an exemplary RTS/CTS exchange in a
wireless communication system.
[0039] FIG. 8 shows a flowchart for an exemplary method of wireless
communication that can be employed within the wireless
communication system of FIG. 1.
[0040] FIG. 9 shows a flowchart for an exemplary method of wireless
communication that can be employed within the wireless
communication system of FIG. 1.
DETAILED DESCRIPTION
[0041] Various aspects of the novel systems, apparatuses, and
methods are described more fully hereinafter with reference to the
accompanying drawings. The teachings disclosure can, however, be
embodied in many different forms and should not be construed as
limited to any specific structure or function presented throughout
this disclosure. Rather, these aspects are provided so that this
disclosure will be thorough and complete, and will fully convey the
scope of the disclosure to those skilled in the art. Based on the
teachings herein one skilled in the art should appreciate that the
scope of the disclosure is intended to cover any aspect of the
novel systems, apparatuses, and methods disclosed herein, whether
implemented independently of or combined with any other aspect of
the invention. For example, an apparatus can be implemented or a
method can be practiced using any number of the aspects set forth
herein. In addition, the scope of the invention is intended to
cover such an apparatus or method which is practiced using other
structure, functionality, or structure and functionality in
addition to or other than the various aspects of the invention set
forth herein. It should be understood that any aspect disclosed
herein can be embodied by one or more elements of a claim.
[0042] Although particular aspects are described herein, many
variations and permutations of these aspects fall within the scope
of the disclosure. Although some benefits and advantages of the
preferred aspects are mentioned, the scope of the disclosure is not
intended to be limited to particular benefits, uses, or objectives.
Rather, aspects of the disclosure are intended to be broadly
applicable to different wireless technologies, system
configurations, networks, and transmission protocols, some of which
are illustrated by way of example in the figures and in the
following description of the preferred aspects. The detailed
description and drawings are merely illustrative of the disclosure
rather than limiting, the scope of the disclosure being defined by
the appended claims and equivalents thereof.
[0043] Wireless network technologies can include various types of
wireless local area networks (WLANs). A WLAN can be used to
interconnect nearby devices together, employing widely used
networking protocols. The various aspects described herein can
apply to any communication standard, such as Wi-Fi or, more
generally, any member of the IEEE 802.11 family of wireless
protocols.
[0044] In some aspects, wireless signals can be transmitted
according to a high-efficiency 802.11 protocol using orthogonal
frequency-division multiplexing (OFDM), direct-sequence spread
spectrum (DSSS) communications, a combination of OFDM and DSSS
communications, or other schemes. Implementations of the
high-efficiency 802.11 protocol can be used for Internet access,
sensors, metering, smart grid networks, or other wireless
applications. Advantageously, aspects of certain devices
implementing this particular wireless protocol can consume less
power than devices implementing other wireless protocols, can be
used to transmit wireless signals across short distances, and/or
can be able to transmit signals less likely to be blocked by
objects, such as humans.
[0045] In some implementations, a WLAN includes various devices
which are the components that access the wireless network. For
example, there can be two types of devices: access points ("APs")
and clients (also referred to as stations, or "STAs"). In general,
an AP serves as a hub or base station for the WLAN and an STA
serves as a user of the WLAN. For example, a STA can be a laptop
computer, a personal digital assistant (PDA), a mobile phone, etc.
In an example, an STA connects to an AP via a Wi-Fi (e.g., IEEE
802.11 protocol such as 802.11ah) compliant wireless link to obtain
general connectivity to the Internet or to other wide area
networks. In some implementations an STA can also be used as an
AP.
[0046] The techniques described herein can be used for various
broadband wireless communication systems, including communication
systems that are based on an orthogonal multiplexing scheme.
Examples of such communication systems include Spatial Division
Multiple Access (SDMA), Time Division Multiple Access (TDMA),
Orthogonal Frequency Division Multiple Access (OFDMA) systems,
Single-Carrier Frequency Division Multiple Access (SC-FDMA)
systems, and so forth. An SDMA system can utilize sufficiently
different directions to concurrently transmit data belonging to
multiple user terminals. A TDMA system can allow multiple user
terminals to share the same frequency channel by dividing the
transmission signal into different time slots, each time slot being
assigned to different user terminal. A TDMA system can implement
GSM or some other standards known in the art. An OFDMA system
utilizes orthogonal frequency division multiplexing (OFDM), which
is a modulation technique that partitions the overall system
bandwidth into multiple orthogonal sub-carriers. These sub-carriers
can also be called tones, bins, etc. With OFDM, each sub-carrier
can be independently modulated with data. An OFDM system can
implement IEEE 802.11 or some other standards known in the art. An
SC-FDMA system can utilize interleaved FDMA (IFDMA) to transmit on
sub-carriers that are distributed across the system bandwidth,
localized FDMA (LFDMA) to transmit on a block of adjacent
sub-carriers, or enhanced FDMA (EFDMA) to transmit on multiple
blocks of adjacent sub-carriers. In general, modulation symbols are
sent in the frequency domain with OFDM and in the time domain with
SC-FDMA. A SC-FDMA system can implement 3GPP-LTE (3rd Generation
Partnership Project Long Term Evolution) or other standards.
[0047] The teachings herein can be incorporated into (e.g.,
implemented within or performed by) a variety of wired or wireless
apparatuses (e.g., nodes). In some aspects, a wireless node
implemented in accordance with the teachings herein can comprise an
access point or an access terminal.
[0048] An access point ("AP") can comprise, be implemented as, or
known as a NodeB, Radio Network Controller ("RNC"), eNodeB, Base
Station Controller ("BSC"), Base Transceiver Station ("BTS"), Base
Station ("BS"), Transceiver Function ("TF"), Radio Router, Radio
Transceiver, Basic Service Set ("BSS"), Extended Service Set ("ES
S"), Radio Base Station ("RBS"), or some other terminology.
[0049] A station ("STA") can also comprise, be implemented as, or
known as a user terminal, an access terminal ("AT"), a subscriber
station, a subscriber unit, a mobile station, a remote station, a
remote terminal, a user agent, a user device, user equipment, or
some other terminology. In some implementations an access terminal
can comprise a cellular telephone, a cordless telephone, a Session
Initiation Protocol ("SIP") phone, a wireless local loop ("WLL")
station, a personal digital assistant ("PDA"), a handheld device
having wireless connection capability, or some other suitable
processing device connected to a wireless modem. Accordingly, one
or more aspects taught herein can be incorporated into a phone
(e.g., a cellular phone or smartphone), a computer (e.g., a
laptop), a portable communication device, a headset, a portable
computing device (e.g., a personal data assistant), an
entertainment device (e.g., a music or video device, or a satellite
radio), a gaming device or system, a global positioning system
device, or any other suitable device that is configured to
communicate via a wireless medium.
[0050] As discussed above, certain of the devices described herein
can implement the 802.11ah standard, for example. Such devices,
whether used as an STA or AP or other device, can be used for smart
metering or in a smart grid network. Such devices can provide
sensor applications or be used in home automation. The devices can
instead or in addition be used in a healthcare context, for example
for personal healthcare. They can also be used for surveillance, to
enable extended-range Internet connectivity (e.g., for use with
hotspots), or to implement machine-to-machine communications.
[0051] FIG. 1 illustrates an example of a wireless communication
system 100 in which aspects of the present disclosure can be
employed. The wireless communication system 100 can operate
pursuant to a wireless standard, for example at least one of the
802.11ah, 802.11ac, 802.11n, 802.11g and 802.11b standards. The
wireless communication system 100 can include an AP 104, which
communicates with STAs 106.
[0052] A variety of processes and methods can be used for
transmissions in the wireless communication system 100 between the
AP 104 and the STAs 106. For example, signals can be transmitted
and received between the AP 104 and the STAs 106 in accordance with
OFDM/OFDMA techniques. If this is the case, the wireless
communication system 100 can be referred to as an OFDM/OFDMA
system. Alternatively, signals can be transmitted and received
between the AP 104 and the STAs 106 in accordance with CDMA
techniques. If this is the case, the wireless communication system
100 can be referred to as a CDMA system.
[0053] A communication link that facilitates transmission from the
AP 104 to one or more of the STAs 106 can be referred to as a
downlink (DL) 108, and a communication link that facilitates
transmission from one or more of the STAs 106 to the AP 104 can be
referred to as an uplink (UL) 110. Alternatively, a downlink 108
can be referred to as a forward link or a forward channel, and an
uplink 110 can be referred to as a reverse link or a reverse
channel.
[0054] The AP 104 can provide wireless communication coverage in a
basic service area (BSA) 102. The AP 104 along with the STAs 106
associated with the AP 104 and that use the AP 104 for
communication can be referred to as a basic service set (BSS). It
should be noted that the wireless communication system 100 may not
have a central AP 104, but rather can function as a peer-to-peer
network between the STAs 106. Accordingly, the functions of the AP
104 described herein can alternatively be performed by one or more
of the STAs 106.
[0055] FIG. 2 illustrates various components that can be utilized
in a wireless device 202 that can be employed within the wireless
communication system 100. The wireless device 202 is an example of
a device that can be configured to implement the various methods
described herein. For example, the wireless device 202 can comprise
the AP 104 or one of the STAs 106.
[0056] The wireless device 202 can include a processor 204 which
controls operation of the wireless device 202. The processor 204
can also be referred to as a central processing unit (CPU). Memory
206, which can include both read-only memory (ROM) and random
access memory (RAM), provides instructions and data to the
processor 204. A portion of the memory 206 can also include
non-volatile random access memory (NVRAM). The processor 204
typically performs logical and arithmetic operations based on
program instructions stored within the memory 206. The instructions
in the memory 206 can be executable to implement the methods
described herein.
[0057] The processor 204 can comprise or be a component of a
processing system implemented with one or more processors. The one
or more processors can be implemented with any combination of
general-purpose microprocessors, microcontrollers, digital signal
processors (DSPs), field programmable gate array (FPGAs),
programmable logic devices (PLDs), controllers, state machines,
gated logic, discrete hardware components, dedicated hardware
finite state machines, or any other suitable entities that can
perform calculations or other manipulations of information.
[0058] The processing system can also include machine-readable
media for storing software. Software shall be construed broadly to
mean any type of instructions, whether referred to as software,
firmware, middleware, microcode, hardware description language, or
otherwise. Instructions can include code (e.g., in source code
format, binary code format, executable code format, or any other
suitable format of code). The instructions, when executed by the
one or more processors, cause the processing system to perform the
various functions described herein.
[0059] The wireless device 202 can also include a housing 208 that
can include a transmitter 210 and a receiver 212 to allow
transmission and reception of data between the wireless device 202
and a remote location. The transmitter 210 and receiver 212 can be
combined into a transceiver 214. An antenna 216 can be attached to
the housing 208 and electrically coupled to the transceiver 214.
The wireless device 202 can also include (not shown) multiple
transmitters, multiple receivers, multiple transceivers, and/or
multiple antennas, which can be utilized during MIMO
communications, for example.
[0060] The wireless device 202 can also include a signal detector
218 that can be used in an effort to detect and quantify the level
of signals received by the transceiver 214. The signal detector 218
can detect such signals as total energy, energy per subcarrier per
symbol, power spectral density and other signals. The wireless
device 202 can also include a digital signal processor (DSP) 220
for use in processing signals. The DSP 220 can be configured to
generate a data unit for transmission. In some aspects, the data
unit can comprise a physical layer data unit (PPDU). In some
aspects, the PPDU is referred to as a packet.
[0061] The wireless device 202 can further comprise a user
interface 222 in some aspects. The user interface 222 can comprise
a keypad, a microphone, a speaker, and/or a display. The user
interface 222 can include any element or component that conveys
information to a user of the wireless device 202 and/or receives
input from the user.
[0062] The various components of the wireless device 202 can be
coupled together by a bus system 226. The bus system 226 can
include a data bus, for example, as well as a power bus, a control
signal bus, and a status signal bus in addition to the data bus.
Those of skill in the art will appreciate the components of the
wireless device 202 can be coupled together or accept or provide
inputs to each other using some other mechanism.
[0063] Although a number of separate components are illustrated in
FIG. 2, those of skill in the art will recognize that one or more
of the components can be combined or commonly implemented. For
example, the processor 204 can be used to implement not only the
functionality described above with respect to the processor 204,
but also to implement the functionality described above with
respect to the signal detector 218 and/or the DSP 220. Further,
each of the components illustrated in FIG. 2 can be implemented
using a plurality of separate elements.
[0064] As discussed above, the wireless device 202 can comprise an
AP 104 or an STA 106, and can be used to transmit and/or receive
communications. The communications exchanged between devices in a
wireless network can include data units which can comprise packets
or frames. In some aspects, the data units can include data frames,
control frames, and/or management frames. Data frames can be used
for transmitting data from an AP and/or a STA to other APs and/or
STAs. Control frames can be used together with data frames for
performing various operations and for reliably delivering data
(e.g., acknowledging receipt of data, polling of APs, area-clearing
operations, channel acquisition, carrier-sensing maintenance
functions, etc.). Management frames can be used for various
supervisory functions (e.g., for joining and departing from
wireless networks, etc.).
[0065] Certain aspects of the present disclosure support allowing
APs 104 to schedule STAs 106 transmissions in optimized ways to
improve efficiency. Both high efficiency wireless (HEW) stations,
stations utilizing an 802.11 high efficiency protocol, and stations
using older or legacy 802.11 protocols, can compete for access to a
wireless medium. The high-efficiency 802.11 protocol described
herein can allow for devices to operate under a modified mechanism
that differentiates between devices that can communicate
concurrently and devices that cannot communicate concurrently.
Accordingly, in the case of apartment buildings or
densely-populated public spaces, APs and/or STAs that use the
high-efficiency 802.11 protocol can experience reduced latency and
increased network throughput even as the number of active wireless
devices increases, thereby improving user experience.
[0066] In some embodiments, APs 104 can control access to a
wireless medium by transmitting a message using a transmission
characteristic such that at least the wireless devices to be
silenced can decode the message and a second group of wireless
devices can access the medium for transmissions. For example, with
respect to FIG. 1, STAs 106a and 106b can be legacy STAs and 106c
and 106d can be HEW STAs. In this embodiment, it can be desirable
to silence the STAs 106a and 106b so that the STAs 106c and 106d
can communicate with the AP 104 without interference from legacy
STAs 106a and 106b. Thus, the transmission characteristic can be
such that at least the STAs 106a and 106b can decode the message.
When the STAs 106a and 106b detect the message, the STAs 106a and
106b can be silenced for the interval as identified by the duration
field within the message. The duration field of the message can be
set such that a predetermined percentage of a total communication
time is reserved for the STAs 106c and 106d to communicate. The
STAs 106c and 106d can also be able to decode the message but can
receive an instruction to not set their network allocation vector
(NAV) and thus not be silenced for the interval identified in the
duration field of the message.
[0067] In some aspects, an AP 104 or a STA 106 can transmit a
message with a transmission characteristic that reserves the medium
for only HEW STAs or a group of HEW STAs by sending a message that
sets the NAV for the legacy STAs but not for the HEW STAs. In other
aspects, an AP 104 or a STA 106 can transmit a message with a
transmission characteristic that reserves the medium for only
legacy STAs or a group of legacy STAs by sending a message that
sets the NAV of the HEW STAs but not the legacy STAs. This would
allow the AP 104 to more efficiently allocate access to the medium
between the HEW STAs and the legacy STAs.
[0068] In one embodiment, the transmission characteristic can be a
new frame format with a new type and new subtype. In this
implementation, with respect to FIG. 1, the STAs 106a and 106b can
be operating in a mode according to a legacy IEEE 802.11 standard
(i.e. IEEE 802.11b) and STAs 106c and 106d can be operating in a
mode according to a IEEE 802.11 high efficiency protocol. In one
embodiment, the new frame can have a similar structure as an
802.11b (or similar protocol) frame such that legacy STAs 106a and
106b can be able to decode the NAV for this new frame irrespective
of the new type and subtype. The STAs 106a and 106b can then set
their NAV according to the new frame. The HEW STAs 106c and 106d,
on the other hand, can decode the new frame but determine that for
this new frame type, as indicated by the type or subtype field,
they can ignore the NAV for the new frame and thus can send
transmissions during the time indicated by the duration field of
the new frame. In some embodiments, the new frame format can be
only decodable by one group of STAs (i.e. the new frame is not
decodable by legacy stations). In this implementation, with respect
to FIG. 1, the STAs 106a and 106b can be operating in a mode
according to a legacy IEEE 802.11 standard (i.e. IEEE 802.11b) and
STAs 106c and 106d can be operating in a mode according to a IEEE
802.11 high efficiency protocol. In this embodiment, the new frame
may only be decodable by STAs 106c and 106d. The STAs 106c and 106d
can then set their NAV according to the new frame while the STAs
106a and 106b can be unable to decode the new frame and thus can
send transmissions as if medium was idle. In some embodiments, the
new frame can also indicate a group of HEW STAs that can set their
NAV or a group of HEW stations that can ignore the NAV, which can
reserve the medium for a certain group of HEW stations. For
example, the new frame can include an indication that STA 106c
should set its NAV while STA 106d can ignore the NAV and transmit
freely. In some aspects the new frame format can be similar to the
format of a request to send (RTS), clear to send (CTS) or a QoS
null frame.
[0069] In some embodiments, the transmission characteristic can be
information in a field of an existing frame format. In one aspect,
the AP 104 can transmit a clear-to-send (CTS)-to-self frame. In one
embodiment, the AP 104 can set the receiver address (RA) of the CTS
frame to a multicast address or to a specific medium access control
(MAC) address to indicate to a first group of STAs to ignore the
NAV of the CTS frame while a second group of STAs can set their NAV
according to the CTS frame. For example, with respect to FIG. 1,
STAs 106a and 106b can be legacy STAs and 106c and 106d can be HEW
STAs. The STAs 106a and 106b can set their NAV according to the
CTS, while the HEW STAs 106c and 106d, on the other hand, can see
the RA multicast address as an indication to not set their NAV and
can thereby be able to transmit during the duration of the CTS. In
another embodiment, the AP 104 can set the receiver address (RA) of
the CTS frame to a multicast address or to a specific medium access
control (MAC) address and use one of the bits in the scrambling
sequence in the service field of the CTS frame to indicate to a
first group of STAs to ignore the NAV of the CTS frame while a
second set of STAs can set their NAV according to the CTS
frame.
[0070] In another aspect, the AP 104 can transmit a request to send
(RTS) frame. In one embodiment, the AP 104 can set the transmitter
address (TA) to a multicast address and use one of the bits in the
scrambling sequence in the service field of the RTS to indicate to
a first group of STAs to ignore the NAV of the RTS frame while a
second group of STAs can set their NAV according to the RTS frame.
For example, with respect to FIG. 1, STAs 106a and 106b can be
legacy STAs and 106c and 106d can be HEW STAs. The STAs 106a and
106b can set their NAV according to the RTS, while the HEW STAs
106c and 106d, on the other hand, can see the TA multicast address
and the use of the one bit in the service field as an indication to
not set their NAV and can thereby be able to transmit during the
duration of the RTS. In other embodiments, the AP 104 can transmit
any data or management frame and set the TA to a multicast address
and use one of the bits in the scrambling sequence in the service
field of the data or management frame to indicate to a first group
of STAs to ignore the NAV of the data or management frame while a
second group of STAs can set their NAV according to the data or
management frame.
[0071] In another aspect, an AP 104 or a STA 106 can transmit a
quality of service (QoS) frame. In one embodiment, the AP 104 can
use a one bit indication in the reserved bits of the QoS control
field to indicate to a first group of STAs to ignore the NAV of the
QoS frame while a second group of STAs can set their NAV according
to the QoS frame. For example, with respect to FIG. 1, STAs 106a
and 106b can be legacy STAs and 106c and 106d can be HEW STAs. The
STAs 106a and 106b can set their NAV according to the QoS, while
the HEW STAs 106c and 106d, on the other hand, can see the one bit
indication in the control field as an indication to not set their
NAV and can thereby be able to transmit during the duration of the
QoS.
[0072] In another aspect, the AP 104 can transmit a control wrapper
frame. In some embodiments the control wrapper frame can carry an
RTS or CTS frame. In one embodiment, the AP 104 can use an invalid
field setting in the high throughput control field of the control
wrapper frame to indicate to a first group of STAs to ignore the
NAV of the control wrapper frame while a second group of STAs can
set their NAV according to the control wrapper frame. For example,
with respect to FIG. 1, STAs 106a and 106b can be legacy STAs and
106c and 106d can be HEW STAs. The STAs 106a and 106b can set their
NAV according to the control wrapper frame (with a RTS, CTS, or
other frame), while the HEW STAs 106c and 106d, on the other hand,
can see the invalid field settings in the high throughput control
field as an indication to not set their NAV and can thereby be able
to transmit during the duration of the control wrapper frame.
[0073] In one embodiment, the transmission characteristic can be
information in a protocol version field. In this embodiment, the AP
104 can transmit a frame with a protocol version field set a value
greater than zero that can be decodable by a first group of STAs to
set the NAV according to the frame while a second group of STAs may
not be able to decode the frame and thus may not set their NAV. For
example, with respect to FIG. 1, STAs 106a and 106b can be legacy
STAs and 106c and 106d can be HEW STAs. The STAs 106a and 106b may
not be able to decode a frame with a protocol version field set to
a value greater than zero, while the HEW STAs 106c and 106d, on the
other hand, can be able to decode this frame and can set their NAV
according to the frame. Thus, the STAs 106a and 106b can be able to
transmit during the duration of the frame.
[0074] In another embodiment, the transmission characteristic can
be information in a duration field. In this embodiment, the AP 104
can transmit a frame with a duration field set to an invalid value
that can be decodable by a first group of STAs to set the NAV
according to the frame while a second group of STAs may not be able
to decode the frame and thus may not set their NAV. For example,
with respect to FIG. 1, STAs 106a and 106b can be legacy STAs and
106c and 106d can be HEW STAs. The STAs 106a and 106b may not be
able to decode a frame with a duration field set to an invalid
value, while the HEW STAs 106c and 106d, on the other hand, can be
able to decode this frame and can set their NAV according to the
frame. Thus, the STAs 106a and 106b can be able to transmit during
the duration of the frame.
[0075] In another embodiment, the transmission characteristic can
be information in a field of an existing frame format. In one
embodiment, the AP 104 can transmit a frame with a duration field
set to zero. The frame can include a new field, such that the new
field can be decodable by a first group of STAs to set the NAV
according to the new field of the frame while a second group of
STAs may not be able to decode the new field in the frame and thus
may not set their NAV. For example, with respect to FIG. 1, STAs
106a and 106b can be legacy STAs and 106c and 106d can be HEW STAs.
The STAs 106a and 106b may not be able to decode the new frame,
while the HEW STAs 106c and 106d, on the other hand, can be able to
decode the new field in the frame and can set their NAV according
to the new field. Thus, the STAs 106a and 106b can be able to
transmit during the duration of the frame.
[0076] In some aspects, an AP 104 or a STA 106 can subsequently
transmit a message with a transmission characteristic such that
only HEW STAs or a group of HEW STAs can reset the NAV while the
legacy STAs do not reset their NAV. In other aspects, an AP 104 can
subsequently transmit a message with a transmission characteristic
such that only legacy STAs or a group of legacy STAs can reset
their NAV while the HEW STAs do not reset their NAV. This would
allow the AP 104 to more efficiently allocate access to the medium
between the HEW STAs and the legacy STAs.
[0077] In one embodiment, the transmission characteristic can be
information in a CF-end frame. In this embodiment the AP 104 can
transmit a CF-end frame and can set the basic service set
identifier (BSSID) to a multicast address to indicate to a first
group of STAs to ignore the CF-end frame while a second group of
STAs can reset their NAV according to the CF-end frame. For
example, with respect to FIG. 1, STAs 106a and 106b can be legacy
STAs and 106c and 106d can be HEW STAs. The STAs 106a and 106b can
reset their NAV according to the CF-end, while the HEW STAs 106c
and 106d, on the other hand, can see the BSSID multicast address as
an indication to not reset their NAV.
[0078] In another embodiment, the transmission characteristic can
be a CF-end frame in a new frame format. In some embodiments, the
new CF-end frame format can be only decodable by one group of STAs.
In this implementation, with respect to FIG. 1, the STAs 106a and
106b can be operating in a mode according to a legacy IEEE 802.11
standard (i.e. IEEE 802.11b) and STAs 106c and 106d can be
operating in a mode according to a IEEE 802.11 high efficiency
protocol. In this embodiment, the new CF-end frame may only be
decodable by STAs 106c and 106d. The STAs 106c and 106d can then
reset their NAV according to the new CF-end frame while the STAs
106a and 106b can be unable to decode the new frame and thus may
not reset their NAV.
[0079] In one embodiment, the transmission characteristic can be a
new frame format with a new type and new subtype, such that the new
frame format is not decodable by legacy stations. In this
implementation, with respect to FIG. 1, the STAs 106a and 106b can
be operating in a mode according to a legacy IEEE 802.11 standard
(i.e. IEEE 802.11b) and STAs 106c and 106d can be operating in a
mode according to a IEEE 802.11 high efficiency protocol. In one
embodiment, the new frame can have a similar structure as an
802.11b (or similar protocol) frame (i.e. a CF-end frame) but STAs
106a and 106b may not be able to decode the new frame and thus may
not reset their NAV. The HEW STAs 106c and 106d, on the other hand,
can decode the new frame and determine that for this new frame
type, they can reset the NAV and thus can access the medium.
[0080] In some embodiments, an AP 104 or a STA 106 can reserve the
medium for variable period of time. In one aspect, the AP 104 or
the STA 106 can send a message instructing the STAs to wait an
indicated number of time slots before attempting to access the
medium. Each STA receiving the message can perform a backoff
procedure with a counter initialized at the indicated time slot
value. After each time slot, the STAs can check to see if the
medium was busy during the time slot. If the medium was busy, the
counter can stay at the previous time slot value. If the medium was
idle, the counter can decrease by one, and can continue to wait
until the counter reaches zero. Thus, the time period the AP 104 or
the STA 106 reserves the medium for can depend on the traffic in
the medium and may not be a defined value.
[0081] Certain aspects of the present disclosure support allowing
APs and STAs to selectively set the NAV of certain subsets of nodes
using an RTS/CTS exchange in optimized ways to improve efficiency.
Generally, wireless networks that use a regular 802.11 protocol
(e.g., 802.11a, 802.11b, 802.11ac, 802.11g, 802.11n, etc.) operate
under a carrier sense multiple access (CSMA) mechanism for medium
access. According to CSMA, devices sense the medium and only
transmit when the medium is sensed to be idle. The use of the CSMA
mechanism can create inefficiencies because some APs or STAs
located inside or outside of a base service area (BSA) can be able
to transmit data without interfering with a transmission made by an
AP or STA in the BSA. As the number of active wireless devices
continues to grow, the inefficiencies can begin to significantly
affect network latency and throughput. The RTS/CTS exchange
protocol described herein can allow for devices to operate under a
modified mechanism that differentiates between devices that can
communicate concurrently with the devices that are exchanging the
RTS and CTS frames and devices that cannot communicate
concurrently. Accordingly, in the case of apartment buildings or
densely-populated public spaces, APs and/or STAs that use the
modified RTS/CTS protocol discussed herein can experience reduced
latency and increased network throughput even as the number of
active wireless devices increases, thereby improving user
experience.
[0082] FIG. 3 is a diagram of an exemplary wireless communication
system 300 for a channel x. In the illustrated embodiment, the
wireless communication system 300 includes a plurality of APs
(e.g., AP1x, AP2x, AP3x, and AP4), each having a BSA 301-304, and
STAs (e.g., STA1x, STA2x, and STA4). In some embodiments the
various operations of APs and STAs described herein can be
interchanged. For each AP-STA link (e.g., reference link 315)
working on channel x, the number of bytes successfully received can
be expressed in the following way:
f ( ch x i n CSMA range Data Tx + ch x outside CSMA range Data Tx +
ch x ACK Tx + ch .noteq. x Data Tx + ch .noteq. x ACK Tx )
##EQU00001##
An RTS/CTS exchange can alter the total number of bytes received by
effectively the data transmissions (Tx) on the channel x outside
the CSMA range and the acknowledgement (ACK) transmissions on
channel x to zero. Nodes that send data transmissions (Tx) on the
channel x outside the CSMA range and nodes that send
acknowledgement (ACK) transmissions on channel x can be considered
"jammers" that can cause interference with a given reference link
315 on channel x. Given that RTS/CTS messages silence the nodes
receiving the messages, usage of RTS/CTS can decrease system
throughput. However, the RTS/CTS exchange can reduce interference
and improve reception for a given STA when there are many devices
present that can cause interference.
[0083] FIG. 4 is a diagram of an exemplary RTS/CTS exchange 400. In
conjunction with FIG. 1, in some embodiments, an AP 104 can
transmit a RTS frame to a STA 106 and the STA 106 can respond to
the RTS frame by sending a CTS frame to the AP 104. An RTS/CTS
exchange can be desirable for hidden node mitigation or for
clearing the medium when data transmission is not successful for
STAs 106. As shown in FIG. 4, the AP1 can transmit an RTS 405 or
other message to STA1 with the RTS 405 deferring all STAs and APs
within the defer range 401. AP2 is outside the defer range 401, and
can be considered a hidden node with respect to the AP1. As shown
in FIG. 4, the AP2 can transmit a message 410 to STA2 with its own
defer range 402 which can interfere with STA1's reception of the
RTS 405 or with its transmission of a responsive CTS frame.
[0084] FIGS. 5 and 6 illustrate the effects of the RTS/CTS system.
FIG. 5 is a diagram 500 of an exemplary RTS/CTS exchange. FIG. 6 is
a time sequence diagram 600 of the RTS/CTS exchange of FIG. 5. In
FIGS. 5 and 6, the AP1 transmits to STA1 a RTS fame 601 with a
defer range 501. STA1 then responds with a CTS frame 602 with a
defer range 502. In conjunction with FIG. 3, the AP2 (hidden node)
is then deferred and will remain for the period 610 while the AP1
transmits a data packet 604 to the STA1 and the STA sends an ACK or
Block ACK 606. Thus, the RTS 601 and CTS 602 can reserve the medium
and prevent interference from any hidden nodes (AP2) during a data
transmission 604.
[0085] However, if the nodes generate RTS/CTS messages to mitigate
the ACK interference effect, the usage of RTS/CTS can be intrusive
on the system. For example, N number of jammers can affect a STA
(STA1x as shown in FIG. 3). In one aspect, the throughput of the
system would equal the sum of the throughputs for all the N jammers
(.SIGMA..sub.j=jammers Thj=Thjammer). The throughput of the system
with an RTS/CTS exchange would equal the throughput of the
non-silenced stations, STA1x as shown (.SIGMA..sub.j.ltoreq.non
silenced STAThj=Throughput of STA1x.ident.Thsta). If the AP1x or
the STA1x are aware of a number M (N>M) such that of the number
N jammers, M jammers should be silenced so that the STA1x can
transmit data with a throughput Thsta*. In such a system, the
system throughput would equal the throughput of STA1x plus the sum
of the throughputs of the non-silenced jammers (e.g.,
Thsta*+.SIGMA..sub.j=N-M non silenced jammers
Thj>Thjammer>Thsta). An AP 104 or a STA 106 can identify the
number of jammers by any conventional means. In some aspects, the
AP 104 can perform a scan procedure to identify neighboring basic
service sets (BSSs) and the related nodes. In some aspects, the AP
104 can then send a querying message (such as, for example, one or
more beacon request messages) to the STA 106 that is the intended
recipient of the data (e.g., STA1 is intended recipient of data 604
in FIG. 6). The BSSs heard by the AP 104 and not contained in the
querying messages of the STA identify the jammers that should not
be silenced (N-M).
[0086] FIG. 7 is a diagram of an exemplary RTS/CTS exchange in a
wireless communication system 700. For example, as shown in FIG. 7,
STA1 and AP1 can use an RTS/CTS exchange to selectively silence
certain jammers within their respective defer ranges 701 and 702.
In this embodiment, it can be desirable to silence the
transmissions at AP2, AP3, AP4, and AP6 and allow the transmission
at AP5 so that AP5 can communicate with STA5 while AP1 communicates
without STA1 interference from jammer nodes.
[0087] In various embodiments, devices such as the AP1 can modulate
a transmit power of the RTS in order to decrease the number of
exposed nodes and sources that generate ACK interference. For
example, the AP1 can gradually increase transmit power of the RTS
so as to silence AP6 but not to silence AP5. Systems and methods
for such transmit power modulation are described in greater detail
below with respect to FIGS. 8 and 9.
[0088] FIG. 8 shows a flowchart 800 for an exemplary method of
wireless communication that can be employed within the wireless
communication system 100 of FIG. 1. The method can be implemented
in whole or in part by the devices described herein, such as the
wireless device 202 shown in FIG. 2. Although the illustrated
method is described herein with reference to the wireless
communication system 100 discussed above with respect to FIG. 1,
the wireless device 202 discussed above with respect to FIG. 2, and
the wireless communication system 700 discussed above with respect
to FIG. 7, a person having ordinary skill in the art will
appreciate that the illustrated method can be implemented by
another device described herein, or any other suitable device.
Although the illustrated method is described herein with reference
to a particular order, in various embodiments, blocks herein can be
performed in a different order, or omitted, and additional blocks
can be added.
[0089] First, at block 810, the wireless device 202 determines an
interference level for a data transmission. For example, the AP1
can determine an interference level for data transmission to the
STA1. In various embodiments, the interference level comprises a
packet error rate (PER) from the AP1 to the STA1. Thus, in some
embodiments, the AP1 can determine PER of the data transmission to
the STA1.
[0090] Next, at block 820, the wireless device 202 sets a
transmission power level, for a message reserving the wireless
medium, based on the interference level. For example, the AP1 can
set a transmission power level for RTS based on the interference
level. As discussed in greater detail herein, in some embodiments,
the AP1 can gradually increase the RTS transmission power level
until the PER falls below a threshold error rate or value.
[0091] Then, at block 830, the wireless device 202 transmits the
message reserving the wireless medium at the set transmission power
level. For example, the AP1 can transmit the RTS at the set
transmission power level. In various embodiments, the message
reserving the wireless medium can include one of a request-to-send
(RTS) packet and a clear-to-send (CTS) packet.
[0092] In various embodiments, the wireless device can identify one
or more potentially interfering devices, order the potentially
interfering devices based on an estimated transmit power level to
reach each potentially interfering device, and set the transmission
power level for the message reserving the wireless medium further
based on the ordering. For example, the AP1 can identify the AP5
and the AP6 as potentially interfering devices. The AP1 can order
the RTS transmission power level estimated to reach the AP5 and
AP6, and the AP1 can set the RTS transmission power level to the
lowest of the two values.
[0093] In various embodiments, setting the transmission power level
of the message reserving the wireless medium can include selecting
a lowest estimated transmit power level in the ordering and
selecting a next highest estimated transmit power level in the
ordering when the interference level satisfies a threshold value
(for example, is greater than, or is less than, the threshold,
depending on the particular interference level or interference
metricused). For example, the AP1 can estimate that the AP6
requires a first RTS transmission power level, and the AP5 requires
a second RTS transmission power level higher than the first. The
AP1 can first transmit an RTS at the first transmission power level
and then measure the PER of data transmission to STA1. If the PER
is greater than a threshold, the AP1 can next transmit an RTS at
the second transmission power level, and so on.
[0094] In various embodiments, identifying the one or more
potentially interfering devices can include scanning for
neighboring basic service sets (BSSs), transmitting a querying
message (such as, for example, a beacon request) to an intended
recipient (e.g., receiving device) of the data transmission, and
identifying devices included in a neighboring BSS, but not visible
to or detected by the intended recipient of the data transmission,
as potentially interfering devices. For example, the AP1 can scan
for neighboring BSSs and can determine that AP5 and AP6 are in
range. The AP1 can query the STA1 to determine that only AP2 and
AP3 are detected by the STA1. In some embodiments, devices visible
to or detected by STA1 comprise devices within the CTS defer range
702 (e.g., AP2, STA2, AP3, STA4, STA6). In some embodiments,
devices not visible or detected by STA 1 comprise devices outside
the CTS defer range 702 (e.g., AP5, STA5, AP6). Thus, the AP1 can
determine that the AP5 and the AP6 are potentially interfering
devices which are detected by the AP1 but not visible or detected
by STA1 (e.g., within RTS defer range 701 and outside CTS defer
range 702).
[0095] In various embodiments, estimated transmit power level can
be based on a transmit power control (TPC) information element (IE)
included in a beacon. For example, the AP1 can receive beacons from
the AP5 and the AP6. Each beacon can include an IE including TCP
information indicative of a transmit power level to reach each
respective AP. In various embodiments, other mechanisms for
estimating or determining a transmit power level can be used.
[0096] In various embodiments, potentially interfering devices can
include devices producing (or capable of producing, or likely to
produce) acknowledgement (ACK) interference. For example, as shown
in FIG. 7, the AP6 can be a potentially interfering device. In
various embodiments herein, transmission power level can be
adjusted based on the entirety, or a subset, of actually or
potentially interfering devices.
[0097] In an embodiment, the method shown in FIG. 8 can be
implemented in a wireless device that can include a determining
circuit, a setting circuit, and a transmitting circuit. Those
skilled in the art will appreciate that a wireless device can have
more components than the simplified wireless device described
herein. The wireless device described herein includes only those
components useful for describing some prominent features of
implementations within the scope of the claims.
[0098] The determining circuit can be configured to determine the
interference level. In an embodiment, the receiving circuit can be
configured to implement block 810 of the flowchart 800 (FIG. 8).
The determining circuit can include one or more of the receiver 212
(FIG. 2), the transceiver 214 (FIG. 2), the antenna 216 (FIG. 2),
the DSP 220 (FIG. 2), the processor 204 (FIG. 2), the signal
detector 218 (FIG. 2), and the memory 206 (FIG. 2). In some
implementations, means for determining can include the determining
circuit.
[0099] The setting circuit can be configured to set the
transmission power level for the message reserving the wireless
medium. In an embodiment, the setting circuit can be configured to
implement block 820 of the flowchart 800 (FIG. 8). The setting
circuit can include one or more of the transmitter 210 (FIG. 2),
the transceiver 214 (FIG. 2), the processor 206 (FIG. 2), the DSP
220 (FIG. 2), and the memory 204 (FIG. 2). In some implementations,
means for setting can include the setting circuit.
[0100] The transmitting circuit can be configured to transmit the
message reserving the wireless medium. In an embodiment, the
transmitting circuit can be configured to implement block 830 of
the flowchart 800 (FIG. 8). The transmitting circuit can include
one or more of the transmitter 210 (FIG. 2), the transceiver 214
(FIG. 2), and the antenna 216 (FIG. 2). In some implementations,
means for transmitting can include the transmitting circuit.
[0101] FIG. 9 shows a flowchart 900 for an exemplary method of
wireless communication that can be employed within the wireless
communication system 100 of FIG. 1. The method can be implemented
in whole or in part by the devices described herein, such as the
wireless device 202 shown in FIG. 2. Although the illustrated
method is described herein with reference to the wireless
communication system 100 discussed above with respect to FIG. 1,
the wireless device 202 discussed above with respect to FIG. 2, and
the wireless communication system 700 discussed above with respect
to FIG. 7, a person having ordinary skill in the art will
appreciate that the illustrated method can be implemented by
another device described herein, or any other suitable device.
Although the illustrated method is described herein with reference
to a particular order, in various embodiments, blocks herein can be
performed in a different order, or omitted, and additional blocks
can be added.
[0102] First, at block 910, the wireless device 202 scans for
neighboring basic service sets. For example, the AP1 can scan for
neighboring basic service sets by listening for beacons from
wireless devices within the neighboring basic service sets. The AP1
can receive beacons from the AP5 and the AP6. In some embodiments,
the beacons can include IEs indicating TCP information. Thus, the
AP1 can estimate a transmission power level to reach each of the
AP5 and the AP6.
[0103] Next, at block 920, the wireless device 202 transmits a
querying message to an intended recipient of data transmission. For
example, the AP1 can transmit a beacon request to the STA1. The
STA1 can receive beacons from the AP1, the AP2, and the AP3. Thus,
the STA1 can identify one or more of the AP1, the AP2, and the AP3
to the AP1. The wireless device 202 can receive a query response
from the intended data recipient. The query response may include a
list of devices from which it has received beacons from (e.g.,
detected devices).
[0104] Then, at block 930, the wireless device 202 identifies one
or more devices included in a neighboring BSS, but not visible to
the intended data recipient. For example, the AP1 can subtract the
set of APs visible to or detected by the STA1 from the set of APs
visible to or detected by the AP1. Thus, the AP1 can identify the
AP5 and the AP6 as potential jammers (e.g., devices within RTS
defer range 701 and outside CTS defer range 702).
[0105] Subsequently, at block 940, the wireless device 202 orders
the identified devices based on an estimated transmit power level
to reach each device. For example, the AP1 can determine transmit
power levels to reach each of AP5 and AP6 (for example, based on
their beacons as discussed above). AP6 can be associated with a
first transmit power level and the AP5 can be associated with a
second transmit power level, higher than the first level. Thus, the
transmit power level of AP6 can be placed first in a vector and the
transmit power level of AP5 can be placed second in the vector.
Additional APs not shown can be similarly ordered.
[0106] Thereafter, at block 950, the wireless device 202 sets the
transmission power level for an RTS to the lowest estimated
transmit power level. For example, the AP1 can set RTS transmission
power level to the first transmit power level associated with the
AP6.
[0107] Next, at block 960, the wireless device 202 performs RTS/CTS
and/or data transmission. For example, the AP1 can transmit the RTS
at the first transmit power level, the STA1 can transmit the CTS,
and the AP1 can transmit data to the STA1 as discussed above with
respect to FIG. 6.
[0108] Then, at block 970, the wireless device 202 can measure the
PER of the data transmission. For example, the AP1 can measure the
PER of the data transmission to the STA1, and can compare the
measured PER to a threshold value. In various embodiments, the
threshold can be preset or dynamically determined. If the PER is
less than or equal to the threshold, the wireless device 202 can
proceed to maintain the currently set RTS transmission power level
at block 980.
[0109] Alternatively, if the PER is greater than the threshold, the
wireless device 202 can proceed to block 990. At block 990, the
wireless device 202 sets RTS transmission power level to the next
highest estimated transmit power in the ordered vector. For
example, the AP1 can set the RTS transmit power level to the second
transmit power associated with the AP5. Where the wireless system
includes additional APs not shown, blocks 960-990 can be repeated
in a similar manner for each new transmission power level.
Accordingly, the wireless device 202 can modulate RTS transmission
power level to increase likelihood of excluding ACK interference
(e.g., AP6) while decreasing the likelihood of silencing exposed
terminals (e.g., AP5).
[0110] A person/one having ordinary skill in the art would
understand that information and signals can be represented using
any of a variety of different technologies and techniques. For
example, data, instructions, commands, information, signals, bits,
symbols, and chips that can be referenced throughout the above
description can be represented by voltages, currents,
electromagnetic waves, magnetic fields or particles, optical fields
or particles, or any combination thereof.
[0111] Various modifications to the implementations described in
this disclosure can be readily apparent to those skilled in the
art, and the generic principles defined herein can be applied to
other implementations without departing from the spirit or scope of
this disclosure. Thus, the disclosure is not intended to be limited
to the implementations shown herein, but is to be accorded the
widest scope consistent with the claims, the principles and the
novel features disclosed herein. The word "exemplary" is used
exclusively herein to mean "serving as an example, instance, or
illustration." Any implementation described herein as "exemplary"
is not necessarily to be construed as preferred or advantageous
over other implementations.
[0112] Certain features that are described in this specification in
the context of separate implementations also can be implemented in
combination in a single implementation. Conversely, various
features that are described in the context of a single
implementation also can be implemented in multiple implementations
separately or in any suitable sub-combination. Moreover, although
features can be described above as acting in certain combinations
and even initially claimed as such, one or more features from a
claimed combination can in some cases be excised from the
combination, and the claimed combination can be directed to a
sub-combination or variation of a sub-combination.
[0113] As used herein, a phrase referring to "at least one of" a
list of items refers to any combination of those items, including
single members. As an example, "at least one of: a, b, or c" is
intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c.
[0114] The various operations of methods described above can be
performed by any suitable means capable of performing the
operations, such as various hardware and/or software component(s),
circuits, and/or module(s). Generally, any operations illustrated
in the Figures can be performed by corresponding functional means
capable of performing the operations.
[0115] The various illustrative logical blocks, modules and
circuits described in connection with the present disclosure can be
implemented or performed with a general purpose processor, a
digital signal processor (DSP), an application specific integrated
circuit (ASIC), a field programmable gate array signal (FPGA) or
other programmable logic device (PLD), discrete gate or transistor
logic, discrete hardware components or any combination thereof
designed to perform the functions described herein. A general
purpose processor can be a microprocessor, but in the alternative,
the processor can be any commercially available processor,
controller, microcontroller or state machine. A processor can 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.
[0116] In one or more aspects, the functions described can be
implemented in hardware, software, firmware, or any combination
thereof. If implemented in software, the functions can 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 can 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 web site, 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. Thus, in some aspects computer readable medium can comprise
non-transitory computer readable medium (e.g., tangible media). In
addition, in some aspects computer readable medium can comprise
transitory computer readable medium (e.g., a signal). Combinations
of the above should also be included within the scope of
computer-readable media.
[0117] The methods disclosed herein comprise one or more steps or
actions for achieving the described method. The method steps and/or
actions can be interchanged with one another without departing from
the scope of the claims. In other words, unless a specific order of
steps or actions is specified, the order and/or use of specific
steps and/or actions can be modified without departing from the
scope of the claims.
[0118] Further, it should be appreciated that modules and/or other
appropriate means for performing the methods and techniques
described herein can be downloaded and/or otherwise obtained by a
user terminal and/or base station as applicable. For example, such
a device can be coupled to a server to facilitate the transfer of
means for performing the methods described herein. Alternatively,
various methods described herein can be provided via storage means
(e.g., RAM, ROM, a physical storage medium such as a compact disc
(CD) or floppy disk, etc.), such that a user terminal and/or base
station can obtain the various methods upon coupling or providing
the storage means to the device. Moreover, any other suitable
technique for providing the methods and techniques described herein
to a device can be utilized.
[0119] While the foregoing is directed to aspects of the present
disclosure, other and further aspects of the disclosure can be
devised without departing from the basic scope thereof, and the
scope thereof is determined by the claims that follow.
* * * * *