U.S. patent application number 15/891253 was filed with the patent office on 2018-06-14 for methods and apparatus for multiple user uplink.
The applicant listed for this patent is QUALCOMM Incorporated. Invention is credited to Gwendolyn Denise Barriac, Simone Merlin, Hemanth Sampath, Sameer Vermani.
Application Number | 20180167324 15/891253 |
Document ID | / |
Family ID | 52583116 |
Filed Date | 2018-06-14 |
United States Patent
Application |
20180167324 |
Kind Code |
A1 |
Merlin; Simone ; et
al. |
June 14, 2018 |
METHODS AND APPARATUS FOR MULTIPLE USER UPLINK
Abstract
A method for wireless communication is provided. The method
comprises transmitting a first wireless message comprising a
request for a first user terminal to transmit uplink data and an
indication of at least one requested operational parameter. The
method also comprises receiving a second wireless message from an
access point in response to the first wireless message, the second
wireless message indicating whether a plurality of user terminals
including the first user terminal is selected to transmit uplink
data, the second wireless message indicating at least one
operational parameter for transmission of uplink data based on the
at least one requested operational parameter.
Inventors: |
Merlin; Simone; (San Diego,
CA) ; Barriac; Gwendolyn Denise; (Encinitas, CA)
; Sampath; Hemanth; (San Diego, CA) ; Vermani;
Sameer; (San Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM Incorporated |
San Diego |
CA |
US |
|
|
Family ID: |
52583116 |
Appl. No.: |
15/891253 |
Filed: |
February 7, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14469306 |
Aug 26, 2014 |
9923822 |
|
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15891253 |
|
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|
61871269 |
Aug 28, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L 1/1861 20130101;
H04L 47/14 20130101; H04W 74/08 20130101; H04W 28/24 20130101; H04W
72/042 20130101; H04W 74/04 20130101; H04L 1/0008 20130101; H04L
47/805 20130101; H04W 72/0453 20130101; H04B 7/0452 20130101; H04L
5/0007 20130101; H04L 1/1858 20130101; H04L 5/0037 20130101; H04B
7/2621 20130101; H04W 72/121 20130101; H04L 1/1621 20130101; H04L
5/0055 20130101; H04W 52/50 20130101; H04L 47/24 20130101; H04W
74/085 20130101; H04L 5/0044 20130101; H04W 74/008 20130101; H04W
28/06 20130101; H04L 2001/0093 20130101; H04L 47/72 20130101; H04L
1/1607 20130101; H04L 1/1854 20130101; H04W 72/0413 20130101; H04W
74/006 20130101; H04L 1/0031 20130101; H04N 7/17309 20130101; H04L
5/003 20130101; H04W 72/12 20130101; H04W 72/1289 20130101; H04W
72/1284 20130101; H04W 52/146 20130101; H04L 5/0005 20130101; H04L
47/12 20130101; H04W 72/0446 20130101 |
International
Class: |
H04L 12/801 20130101
H04L012/801; H04W 74/08 20090101 H04W074/08; H04B 7/26 20060101
H04B007/26; H04L 1/18 20060101 H04L001/18; H04L 5/00 20060101
H04L005/00; H04B 7/0452 20170101 H04B007/0452; H04W 74/04 20090101
H04W074/04; H04W 74/00 20090101 H04W074/00; H04W 72/12 20090101
H04W072/12; H04W 72/04 20090101 H04W072/04; H04W 52/14 20090101
H04W052/14; H04L 12/851 20130101 H04L012/851 |
Claims
1. A method for wireless communication, comprising: transmitting,
by a first user terminal, at a transmission power level, a first
wireless message comprising a request for the first user terminal
to transmit uplink data, an indication based on at least the
transmission power level, and an indication of at least one
requested operational parameter; and receiving by the first user
terminal, a second wireless message from an access point in
response to the first wireless message, the second wireless message
indicating which first user terminals of a plurality of user
terminals including the first user terminal is selected to transmit
the uplink data, indicating a transmit power for use by the first
user terminal to transmit the uplink data, and indicating at least
one operational parameter for transmission of the uplink data based
on the at least one requested operational parameter.
2. The method of claim 1, wherein the first wireless message
comprises a data frame.
3. The method of claim 1, wherein the indication based on at least
the transmission power level is a TX power field.
4. The method of claim 1, wherein the at least one requested
operational parameter comprises a transmission time for the uplink
data.
5. The method of claim 1, wherein the indication based on at least
the transmission power level can be used by the access point to
adapt the indication of the transmit power for use by the first
user terminal to transmit the uplink data.
6. The method of claim 1, wherein the second wireless message
comprises a trigger frame.
7. The method of claim 1, wherein the indication of the transmit
power for use by the first user terminal to transmit the uplink
data is based on the transmission power level of the first wireless
message.
8. The method of claim 1, wherein the indication of the transmit
power for use by the first user terminal to transmit the uplink
data is a Power Adjustment field.
9. The method of claim 8, wherein the Power Adjustment field
indicates a power backoff value.
10. The method of claim 1, further comprising transmitting the
uplink data by the first user terminal in an uplink multiuser
multiple-input multiple-output (UL-MU-MIMO) transmission.
11. The method of claim 10, wherein transmitting the uplink data is
performed concurrently with another user terminal of the plurality
of user terminals selected to transmit uplink data.
12. A device for wireless communication, comprising: a transmitter
configured to transmit, at a transmission power level, a first
wireless message comprising a request for a first user terminal to
transmit uplink data, an indication based on at least the
transmission power level, and an indication of at least one
requested operational parameter; and a receiver configured to
receive a second wireless message from an access point in response
to the first wireless message, the second wireless message
indicating which user terminals of a plurality of user terminals
including the first user terminal is selected to transmit the
uplink data, indicating a transmit power for use by the first user
terminal to transmit the uplink data, and indicating at least one
operational parameter for transmission of the uplink data based on
the at least one requested operational parameter.
13. The device of claim 12, wherein the at least one requested
operational parameter comprises a transmission time for the uplink
data.
14. The device of claim 13, wherein the transmission time indicates
a time duration for an uplink multiuser multiple-input
multiple-output transmission opportunity.
15. The device of claim 13, wherein the transmission time indicates
a time duration required for the first user terminal to transmit
the uplink data at a planned modulation and coding scheme.
16. A method for wireless communication, comprising: receiving a
first wireless message comprising a request for a first user
terminal to transmit uplink data, an indication based on at least a
transmission power level of the first wireless message, and an
indication of at least one requested operational parameter;
determining a transmit power for use by the first user terminal to
transmit the uplink data; and transmitting a second wireless
message in response to the first wireless message, the second
wireless message indicating which user terminals of a plurality of
user terminals including the first user terminal is selected to
transmit uplink data, indicating the transmit power, and indicating
at least one operational parameter for transmission of the uplink
data based on the at least one requested operational parameter.
17. The method of claim 16, wherein the at least one operational
parameter indicates a number of spatial streams to employ for
uplink transmission.
18. The method of claim 16, wherein the at least one operational
parameter indicates a channel for uplink transmissions.
19. A device for wireless communication, comprising: a receiver
configured to: receiving a first wireless message comprising a
request for a first user terminal to transmit uplink data, an
indication based on at least a transmission power level of the
first wireless message, and an indication of at least one requested
operational parameter, determining a transmit power for use by the
first user terminal to transmit the uplink data; and a transmitter
configured to transmit a second wireless message in response to the
first wireless message, the second wireless message indicating
which user terminals of a plurality of user terminals including the
first user terminal is selected to transmit the uplink data,
indicating the transmit power, and at least one operational
parameter for transmission of the uplink data based on the at least
one requested operational parameter.
20. The device of claim 19, wherein the at least one operational
parameter indicates a traffic identifier for uplink transmissions.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation application of pending
U.S. patent application Ser. No. 14/469,306, filed Aug. 26, 2014,
and entitled "METHODS AND APPARATUS FOR MULTIPLE USER UPLINK,"
which claims the benefit of U.S. Provisional Application No.
61/871,269 filed Aug. 28, 2013, and entitled "METHODS AND APPARATUS
FOR MULTIPLE USER UPLINK." The content of each of these prior
applications is considered part of this application, and is hereby
incorporated 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 multiple user uplink communication in a wireless
network.
BACKGROUND
[0003] In many telecommunication systems, communications networks
are used to exchange messages among several interacting
spatially-separated devices. Networks may be classified according
to geographic scope, which could be, for example, a metropolitan
area, a local area, or a personal area. Such networks may 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] In order to address the issue of increasing bandwidth
requirements that are demanded for wireless communications systems,
different schemes are being developed to allow multiple user
terminals to communicate with a single access point by sharing the
channel resources while achieving high data throughputs. With
limited communication resources, it is desirable to reduce the
amount of traffic passing between the access point and the multiple
terminals. For example, when multiple terminals send uplink
communications to the access point, it is desirable to minimize the
amount of traffic to complete the uplink of all transmissions.
Thus, there is a need for an improved protocol for uplink
transmissions from multiple terminals.
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 for wireless
communication.
[0009] The method comprises transmitting a first wireless message
comprising a request for a first user terminal to transmit uplink
data and an indication of at least one requested operational
parameter. The method also comprises receiving a second wireless
message from an access point in response to the first wireless
message, the second wireless message indicating whether a plurality
of user terminals including the first user terminal is selected to
transmit uplink data, the second wireless message indicating at
least one operational parameter for transmission of uplink data
based on the at least one requested operational parameter.
[0010] Another aspect of the disclosure provides a device for
wireless communication. The device comprises a transmitter
configured to transmit a first wireless message comprising a
request for a first user terminal to transmit uplink data and an
indication of at least one requested operational parameter. The
device also comprises a receiver configured to receive a second
wireless message from an access point in response to the first
wireless message, the second wireless message indicating whether a
plurality of user terminals including the first user terminal is
selected to transmit uplink data, the second wireless message
indicating at least one operational parameter for transmission of
uplink data based on the at least one requested operational
parameter.
[0011] Another aspect of the disclosure provides a method for
wireless communication. The method comprises receiving a first
wireless message comprising a request for a first user terminal to
transmit uplink data and an indication of at least one requested
operational parameter. The method also comprises transmitting a
second wireless message in response to the first wireless message,
the second wireless message indicating whether a plurality of user
terminals including the first user terminal is selected to transmit
uplink data, the second wireless message indicating at least one
operational parameter for transmission of uplink data based on the
at least one requested operational parameter.
[0012] Another aspect of the disclosure provides a device for
wireless communication. The device comprises a receiver configured
to receive a first wireless message comprising a request for a
first user terminal to transmit uplink data and an indication of at
least one requested operational parameter. The device also
comprises a transmitter configured to transmit a second wireless
message in response to the first wireless message, the second
wireless message indicating whether a plurality of user terminals
including the first user terminal is selected to transmit uplink
data, the second wireless message indicating at least one
operational parameter for transmission of uplink data based on the
at least one requested operational parameter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 illustrates a multiple-access multiple-input
multiple-output system with access points and user terminals.
[0014] FIG. 2 illustrates a block diagram of the access point 110
and two user terminals 120m and 120x in a multiple-input
multiple-output system.
[0015] FIG. 3 illustrates various components that may be utilized
in a wireless device that may be employed within a wireless
communication system.
[0016] FIG. 4 shows a time diagram of an example frame exchange of
an uplink multi-user multiple-input multiple-output
communication.
[0017] FIG. 5 shows a time sequence diagram of another example
frame exchange of an uplink multi-user multiple-input
multiple-output communication.
[0018] FIG. 6 shows a time sequence diagram of another example
frame exchange of an uplink multi-user multiple-input
multiple-output communication.
[0019] FIG. 7 is a time sequence diagram showing, a multi-user
multiple-input multiple-output communications including a user
terminal sending a request message to an AP to request and
initialize an UL-MU-MIMO transmission.
[0020] FIG. 8 shows a time sequence diagram of uplink multi-user
multiple-input multiple-output communication.
[0021] FIG. 9 shows a diagram of an example of a clear to transmit
frame format.
[0022] FIG. 10 shows a diagram of a request message sent by a user
terminal to request transmission of uplink data
[0023] FIG. 11 shows a diagram of a request to transmit frame.
[0024] FIG. 12 shows a flow chart of a method for requesting
transmission of uplink data.
DETAILED DESCRIPTION
[0025] Various aspects of the novel systems, apparatuses, and
methods are described more fully hereinafter with reference to the
accompanying drawings. The teachings disclosure may, 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 may be implemented or a
method may 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 may be embodied by one or more elements of a claim.
[0026] 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.
[0027] Wireless network technologies may include various types of
wireless local area networks (WLANs). A WLAN may be used to
interconnect nearby devices together, employing widely used
networking protocols. The various aspects described herein may
apply to any communication standard, such as Wi-Fi or, more
generally, any member of the IEEE 802.11 family of wireless
protocols.
[0028] In some aspects, wireless signals may 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 may be used for Internet access,
sensors, metering, smart grid networks, or other wireless
applications. Advantageously, aspects of certain devices
implementing this particular wireless protocol may consume less
power than devices implementing other wireless protocols, may be
used to transmit wireless signals across short distances, and/or
may be able to transmit signals less likely to be blocked by
objects, such as humans.
[0029] In some implementations, a WLAN includes various devices
which are the components that access the wireless network. For
example, there may 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 may 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 may also be used as an
AP.
[0030] The techniques described herein may 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 may utilize sufficiently
different directions to simultaneously transmit data belonging to
multiple user terminals. A TDMA system may 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 may 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
may also be called tones, bins, etc. With OFDM, each sub-carrier
may be independently modulated with data. An OFDM system may
implement IEEE 802.11 or some other standards known in the art. An
SC-FDMA system may 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 may implement 3GPP-LTE (3rd Generation
Partnership Project Long Term Evolution) or other standards.
[0031] The teachings herein may 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 may comprise an
access point or an access terminal.
[0032] An access point ("AP") may 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
("ESS"), Radio Base Station ("RBS"), or some other terminology.
[0033] A station "STA" may 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
may 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 may 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.
[0034] FIG. 1 is a diagram that illustrates a multiple-access
multiple-input multiple-output (MIMO) system 100 with access points
and user terminals. For simplicity, only one access point 110 is
shown in FIG. 1. An access point is generally a fixed station that
communicates with the user terminals and may also be referred to as
a base station or using some other terminology. A user terminal or
STA may be fixed or mobile and may also be referred to as a mobile
station or a wireless device, or using some other terminology. The
access point 110 may communicate with one or more user terminals
120 at any given moment on the downlink and uplink. The downlink
(i.e., forward link) is the communication link from the access
point to the user terminals, and the uplink (i.e., reverse link) is
the communication link from the user terminals to the access point.
A user terminal may also communicate peer-to-peer with another user
terminal. A system controller 130 couples to and provides
coordination and control for the access points.
[0035] While portions of the following disclosure will describe
user terminals 120 capable of communicating via Spatial Division
Multiple Access (SDMA), for certain aspects, the user terminals 120
may also include some user terminals that do not support SDMA.
Thus, for such aspects, the AP 110 may be configured to communicate
with both SDMA and non-SDMA user terminals. This approach may
conveniently allow older versions of user terminals ("legacy"
stations) that do not support SDMA to remain deployed in an
enterprise, extending their useful lifetime, while allowing newer
SDMA user terminals to be introduced as deemed appropriate.
[0036] The system 100 employs multiple transmit and multiple
receive antennas for data transmission on the downlink and uplink.
The access point 110 is equipped with N.sub.ap antennas and
represents the multiple-input (MI) for downlink transmissions and
the multiple-output (MO) for uplink transmissions. A set of K
selected user terminals 120 collectively represents the
multiple-output for downlink transmissions and the multiple-input
for uplink transmissions. For pure SDMA, it is desired to have
N.sub.ap<K<1 if the data symbol streams for the K user
terminals are not multiplexed in code, frequency or time by some
means. K may be greater than N.sub.ap if the data symbol streams
can be multiplexed using TDMA technique, different code channels
with CDMA, disjoint sets of sub-bands with OFDM, and so on. Each
selected user terminal may transmit user-specific data to and/or
receive user-specific data from the access point. In general, each
selected user terminal may be equipped with one or multiple
antennas (i.e., N.sub.ut.gtoreq.1). The K selected user terminals
can have the same number of antennas, or one or more user terminals
may have a different number of antennas.
[0037] The SDMA system 100 may be a time division duplex (TDD)
system or a frequency division duplex (FDD) system. For a TDD
system, the downlink and uplink share the same frequency band. For
an FDD system, the downlink and uplink use different frequency
bands. The MIMO system 100 may also utilize a single carrier or
multiple carriers for transmission. Each user terminal may be
equipped with a single antenna (e.g., in order to keep costs down)
or multiple antennas (e.g., where the additional cost can be
supported). The system 100 may also be a TDMA system if the user
terminals 120 share the same frequency channel by dividing
transmission/reception into different time slots, where each time
slot may be assigned to a different user terminal 120.
[0038] FIG. 2 illustrates a block diagram of the access point 110
and two user terminals 120m and 120x in MIMO system 100. The access
point 110 is equipped with N.sub.t antennas 224a through 224ap. The
user terminal 120m is equipped with N.sub.ut,m antennas 252.sub.ma
through 252.sub.mu, and the user terminal 120x is equipped with
N.sub.ut,x antennas 252.sub.xa through 252.sub.xu. The access point
110 is a transmitting entity for the downlink and a receiving
entity for the uplink. The user terminal 120 is a transmitting
entity for the uplink and a receiving entity for the downlink. As
used herein, a "transmitting entity" is an independently operated
apparatus or device capable of transmitting data via a wireless
channel, and a "receiving entity" is an independently operated
apparatus or device capable of receiving data via a wireless
channel. In the following description, the subscript "dn" denotes
the downlink, the subscript "up" denotes the uplink, N.sub.up user
terminals are selected for simultaneous transmission on the uplink,
and Nan user terminals are selected for simultaneous transmission
on the downlink. N.sub.up may or may not be equal to N.sub.dn, and
N.sub.up and N.sub.dn may be static values or may change for each
scheduling interval. Beam-steering or some other spatial processing
technique may be used at the access point 110 and/or the user
terminal 120.
[0039] On the uplink, at each user terminal 120 selected for uplink
transmission, a TX data processor 288 receives traffic data from a
data source 286 and control data from a controller 280. The TX data
processor 288 processes (e.g., encodes, interleaves, and modulates)
the traffic data for the user terminal based on the coding and
modulation schemes associated with the rate selected for the user
terminal and provides a data symbol stream. A TX spatial processor
290 performs spatial processing on the data symbol stream and
provides N.sub.ut,m transmit symbol streams for the N.sub.ut,m
antennas. Each transmitter unit ("TMTR") 254 receives and processes
(e.g., converts to analog, amplifies, filters, and frequency
upconverts) a respective transmit symbol stream to generate an
uplink signal. N.sub.ut,m transmitter units 254 provide N.sub.ut,m
uplink signals for transmission from N.sub.ut,m antennas 252, for
example to transmit to the access point 110.
[0040] N.sub.up user terminals may be scheduled for simultaneous
transmission on the uplink. Each of these user terminals may
perform spatial processing on its respective data symbol stream and
transmit its respective set of transmit symbol streams on the
uplink to the access point 110.
[0041] At the access point 110, N.sub.up antennas 224a through
224.sub.ap receive the uplink signals from all N.sub.up user
terminals transmitting on the uplink. Each antenna 224 provides a
received signal to a respective receiver unit ("RCVR") 222. Each
receiver unit 222 performs processing complementary to that
performed by transmitter unit 254 and provides a received symbol
stream. An RX spatial processor 240 performs receiver spatial
processing on the N.sub.up received symbol streams from N.sub.up
receiver units 222 and provides N.sub.up recovered uplink data
symbol streams. The receiver spatial processing may be performed in
accordance with the channel correlation matrix inversion (CCMI),
minimum mean square error (MMSE), soft interference cancellation
(SIC), or some other technique. Each recovered uplink data symbol
stream is an estimate of a data symbol stream transmitted by a
respective user terminal. An RX data processor 242 processes (e.g.,
demodulates, deinterleaves, and decodes) each recovered uplink data
symbol stream in accordance with the rate used for that stream to
obtain decoded data. The decoded data for each user terminal may be
provided to a data sink 244 for storage and/or a controller 230 for
further processing.
[0042] On the downlink, at the access point 110, a TX data
processor 210 receives traffic data from a data source 208 for Nan
user terminals scheduled for downlink transmission, control data
from a controller 230, and possibly other data from a scheduler
234. The various types of data may be sent on different transport
channels. TX data processor 210 processes (e.g., encodes,
interleaves, and modulates) the traffic data for each user terminal
based on the rate selected for that user terminal. The TX data
processor 210 provides N.sub.dn downlink data symbol streams for
the N.sub.th, user terminals. A TX spatial processor 220 performs
spatial processing (such as a precoding or beamforming) on the
N.sub.dn downlink data symbol streams, and provides N.sub.up
transmit symbol streams for the N.sub.up antennas. Each transmitter
unit 222 receives and processes a respective transmit symbol stream
to generate a downlink signal. N.sub.up transmitter units 222 may
provide N.sub.up downlink signals for transmission from N.sub.up
antennas 224, for example to transmit to the user terminals
120.
[0043] At each user terminal 120, N.sub.ut,m antennas 252 receive
the N.sub.up downlink signals from the access point 110. Each
receiver unit 254 processes a received signal from an associated
antenna 252 and provides a received symbol stream. An RX spatial
processor 260 performs receiver spatial processing on N.sub.ut,m
received symbol streams from N.sub.ut,m receiver units 254 and
provides a recovered downlink data symbol stream for the user
terminal 120. The receiver spatial processing may be performed in
accordance with the CCMI, MMSE, or some other technique. An RX data
processor 270 processes (e.g., demodulates, deinterleaves and
decodes) the recovered downlink data symbol stream to obtain
decoded data for the user terminal.
[0044] At each user terminal 120, a channel estimator 278 estimates
the downlink channel response and provides downlink channel
estimates, which may include channel gain estimates, SNR estimates,
noise variance and so on. Similarly, a channel estimator 228
estimates the uplink channel response and provides uplink channel
estimates. Controller 280 for each user terminal typically derives
the spatial filter matrix for the user terminal based on the
downlink channel response matrix H.sub.dn,m for that user terminal.
Controller 230 derives the spatial filter matrix for the access
point based on the effective uplink channel response matrix
H.sub.up,eff. The controller 280 for each user terminal may send
feedback information (e.g., the downlink and/or uplink
eigenvectors, eigenvalues, SNR estimates, and so on) to the access
point 110. The controllers 230 and 280 may also control the
operation of various processing units at the access point 110 and
user terminal 120, respectively.
[0045] FIG. 3 illustrates various components that may be utilized
in a wireless device 302 that may be employed within the wireless
communication system 100. The wireless device 302 is an example of
a device that may be configured to implement the various methods
described herein. The wireless device 302 may implement an access
point 110 or a user terminal 120.
[0046] The wireless device 302 may include a processor 304 which
controls operation of the wireless device 302. The processor 304
may also be referred to as a central processing unit (CPU). Memory
306, which may include both read-only memory (ROM) and random
access memory (RAM), provides instructions and data to the
processor 304. A portion of the memory 306 may also include
non-volatile random access memory (NVRAM). The processor 304 may
perform logical and arithmetic operations based on program
instructions stored within the memory 306. The instructions in the
memory 306 may be executable to implement the methods described
herein.
[0047] The processor 304 may comprise or be a component of a
processing system implemented with one or more processors. The one
or more processors may 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.
[0048] The processing system may 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 may 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.
[0049] The wireless device 302 may also include a housing 308 that
may include a transmitter 310 and a receiver 312 to allow
transmission and reception of data between the wireless device 302
and a remote location. The transmitter 310 and receiver 312 may be
combined into a transceiver 314. A single or a plurality of
transceiver antennas 316 may be attached to the housing 308 and
electrically coupled to the transceiver 314. The wireless device
302 may also include (not shown) multiple transmitters, multiple
receivers, and multiple transceivers.
[0050] The wireless device 302 may also include a signal detector
318 that may be used in an effort to detect and quantify the level
of signals received by the transceiver 314. The signal detector 318
may detect such signals as total energy, energy per subcarrier per
symbol, power spectral density and other signals. The wireless
device 302 may also include a digital signal processor (DSP) 320
for use in processing signals.
[0051] The various components of the wireless device 302 may be
coupled together by a bus system 322, which may include a power
bus, a control signal bus, and a status signal bus in addition to a
data bus.
[0052] Certain aspects of the present disclosure support
transmitting an uplink (UL) signal from multiple UTs to an AP. In
some embodiments, the UL signal may be transmitted in a multi-user
MIMO (MU-MIMO) system. Alternatively, the UL signal may be
transmitted in a multi-user FDMA (MU-FDMA) or similar FDMA system.
Specifically, FIGS. 4-8 illustrate uplink MU-MIMO (UL-MU-MIMO)
transmissions 410A and 410B that would apply equally to UL-FDMA
transmissions. In these embodiments, UL-MU-MIMO or UL-FDMA
transmissions can be sent simultaneously from multiple STAs to an
AP and may create efficiencies in wireless communication.
[0053] An increasing number of wireless and mobile devices put
increasing stress on bandwidth requirements that are demanded for
wireless communications systems. With limited communication
resources, it is desirable to reduce the amount of traffic passing
between the AP and the multiple STAs. For example, when multiple
terminals send uplink communications to the access point, it is
desirable to minimize the amount of traffic to complete the uplink
of all transmissions. Thus, embodiments described herein support
utilizing communication exchanges, scheduling and certain frames
for increasing throughput of uplink transmissions to the AP.
[0054] FIG. 4 is a time sequence diagram 400 showing an example of
an UL-MU-MIMO protocol 400 that may be used for UL communications.
As shown in FIG. 4, in conjunction with FIG. 1, the AP 110 may
transmit a clear to transmit (CTX) message 402 to the user
terminals 120 indicating which user terminals 120 may participate
in the UL-MU-MIMO scheme, such that a particular UT 120 knows to
start an UL-MU-MIMO transmission. In some embodiments, the CTX
message may be transmitted in a payload portion of a physical layer
convergence protocol (PLCP) protocol data units (PPDUs). An example
of a CTX frame structure is described more fully below with
reference to FIG. 10.
[0055] Once a user terminal 120 receives a CTX message 402 from the
AP 110 where the user terminal is listed, the user terminal 120 may
transmit the UL-MU-MIMO transmission 410. In FIG. 4A, STA 120A and
STA 120B transmit UL-MU-MIMO transmissions 410A and 410B,
respectively, containing physical layer convergence protocol (PLCP)
protocol data units (PPDUs). Upon receiving the UL-MU-MIMO
transmissions 410A and 410B, the AP 110 may transmit block
acknowledgments (BAs) 470 to the user terminals 120A and 120B.
[0056] Not all APs 110 or user terminals 120 may support UL-MU-MIMO
or UL-FDMA operation. A capability indication from a user terminal
120 may be indicated in a high efficiency wireless (HEW) capability
element that is included in an association request or probe request
and may include a bit indicating capability, the maximum number of
spatial streams a user terminal 120 can use in a UL-MU-MIMO
transmission, the frequencies a user terminal 120 can use in a
UL-FDMA transmission, the minimum and maximum power and granularity
in the power backoff, and the minimum and maximum time adjustment a
user terminal 120 can perform.
[0057] A capability indication from an AP 110 may be indicated in a
HEW capability element that is included in an association response,
beacon or probe response and may include a bit indicating
capability, the maximum number of spatial streams a single user
terminal 120 can use in a UL-MU-MIMO transmission, the frequencies
a single user terminal 120 can use in a UL-FDMA transmission, the
required power control granularity, and the required minimum and
maximum time adjustment a user terminal 120 should be able to
perform.
[0058] In one embodiment, capable user terminals 120 may send a
request message to a capable AP to be part of the UL-MU-MIMO (or
UL-FDMA) protocol. In one aspect, an AP 110 may respond by granting
the under terminal 120 the use of the UL-MU-MIMO feature or the AP
110 may deny the user terminal's request. The AP 110 may grant the
use of the UL-MU-MIMO and the user terminal 120 may expect a CTX
message 402 at a variety of times. Additionally, once a user
terminal 120 is enabled to operate the UL-MU-MIMO feature, the user
terminal 120 may be subject to following a certain operation mode.
The user terminal 120 and the AP 110 may support multiple operation
modes and the AP 110 may indicate to the user terminal 120 which
mode to use in a HEW capability element, a management frame, or in
an operation element. In one aspect, a user terminal 120 may change
the operation mode and parameters dynamically during operation by
sending a different operating element to the AP 110. In another
aspect the AP 110 may switch the operation mode dynamically during
operation by sending an updated operating element or a management
frame to the user terminal 120, or by sending the updated operating
element or the updated management frame in a beacon. In another
aspect, the operation mode may be determined by the AP 110 in the
setup phase and may be determined per user terminal 120 or for a
group of user terminals 120. In another aspect the operation mode
may be specified per traffic identifier (TID).
[0059] In some operation modes of UL-MU-MIMO transmissions, a user
terminal 120 may receive a CTX message from an AP 110 and
immediately send a response to the AP 110. The response may be in
the form of a clear to send (CTS) message or another type of
message. The requirement to send the CTS message may be indicated
in the CTX message or the requirement may be indicated in the setup
phase of the communication between the AP 110 and the user terminal
120.
[0060] FIG. 5 is a time sequence diagram 500 that, in conjunction
with FIG. 1, shows an example of an operation mode of UL-MU-MIMO
transmissions between an AP 110 and user terminals 120A and 120B.
As shown in FIG. 5, UT 120A may transmit a CTS message 408A and UT
120B may transmit a CTS message 408B in response to receiving the
CTX message 402 from the AP 110. The modulation and coding scheme
(MCS) of the CTS message 408A and the CTS message 408B may be based
on the MCS of the received CTX message 402. In this embodiment, the
CTS message 408A and the CTS message 408B contain the same amount
of bits and the same scrambling sequence so that they may be
transmitted to the AP 110 at the same time. A duration field of the
CTS messages 408A and 408B may be based on a duration field in the
CTX by removing the time for the CTX PPDU. The user terminal 120A
may send an UL-MU-MIMO transmission 410A to the AP 110 according to
the CTX message 402 and the user terminal 120B may also send an
UL-MU-MIMO transmission 410B to the AP 110 according to the CTX
message 402. The AP 110 may then send an acknowledgment (ACK)
message 475 to the user terminals 120A and 120B. In some aspects,
the ACK message 475 may include serial ACK messages sent to each
user terminal 120 or the ACK message 475 may include BAs. In some
aspects the ACKs 475 may be polled. This embodiment of FIG. 5 may
improve transmission efficiency by providing concurrent
transmission of CTS messages 408 from multiple user terminals 120
to an AP 110, compared to sequential transmission, thereby saving
time and reducing the possibility of interference.
[0061] FIG. 6 is a time sequence diagram 600 that, in conjunction
with FIG. 1, shows an example of an operation mode of UL-MU-MIMO
transmissions. In this embodiment, user terminals 120A and 120B may
receive a CTX message 402 from an AP 110. The CTX message 402 may
indicate a time (T) 406 after the end of the PPDU carrying the CTX
message 402 for the user terminals 120A and 120B to transmit
UL-MU-MIMO transmissions. The T 406 may be a short interframe space
(SIFS), a point interframe space (PIFS), or another time. The T may
include time offsets as indicated by the AP 110 in the CTX message
402 or via a management frame. The SIFS and PIFS time may be fixed
in a standard or may be indicated by the AP 110 in the CTX message
402 or in a management frame. The T 406 may improve synchronization
between the AP110 and the user terminals 120A and 120B and it may
allow the user terminals 120A and 120B sufficient time to process
the CTX message 402, or other messages, before sending their
UL-MU-MIMO transmissions.
[0062] In some circumstances, a user terminal 120 may have uplink
data to upload to the AP 110 but the user terminal 120 may not have
received a CTX message 402 or another message indicating that the
user terminal 120 may start an UL-MU-MIMO transmission. In certain
UL-MU-MIMO operation modes, the user terminals 120 may not transmit
data outside of an UL-MU-MIMO transmission opportunity (TXOP)
(e.g., after receiving a CTX message). In certain operation modes,
the user terminals 120 may transmit a request message to the AP 110
to initialize a UL-MU-MIMO transmission and may then transmit the
uplink data to the AP 110 during the subsequent UL-MU-MIMO TXOP, if
for example, they are instructed to do so in a CTX message. The
request message In some operation modes, the request message may be
the only message type that a user terminal 120 may use to initiate
a UL-MU-MIMO TXOP. In some embodiments, the user terminal 120 may
not transmit outside of an UL-MU-MIMO TXOP other than by sending a
request message.
[0063] FIG. 7 is a time sequence diagram 700 showing, in
conjunction with FIG. 1, a UL-MU-MIMO communications including a
user terminal 120A sending a request message 701 to the AP 110 to
request and initialize an UL-MU-MIMO transmission. The request
message 701 sent to the AP 110 by the user terminal 120A may
include information regarding UL-MU-MIMO transmissions. In other
embodiments, the user terminal 120B may send the request message
701. As shown in FIG. 7, the AP 110 may respond to the request
message 701 with a trigger frame message 702 (e.g., CTX 402)
granting transmission of uplink data to the user terminal 120A
immediately following the trigger frame 702. The trigger frame 402
may also grant a UL-MU-MIMO TXOP 730 to user terminal 120A and user
terminal 120B for concurrently sending a UL-MU-MIMO transmission
410B with a UL-MU-MIMO transmission 410A, both transmissions 410A
and 410B immediately following the trigger frame 702.
[0064] The request message 701 requesting a UL-MU-MIMO TXOP may
comprise an request-to-send (RTS), a data frame, a quality of
service (QoS) null frame, a power save (PS) poll, or a request to
transmit (RTX) frame, the frame indicating that the user terminal
120 has uplink data to transmit to the AP 110. In embodiments where
the request message 701 comprises a data frame or a QoS null frame,
bits 8-15 of the QoS control field may indicate a non-empty queue.
The user terminal 120 may determine in the setup phase which data
frames (e.g., RTS, data frame, QoS Null frame, PS-poll) will
trigger a UL-MU-MIMO transmission.
[0065] In another aspect, the AP 110 may respond to the request
message 701 with a CTS that grants a single-user (SU) UL TXOP. In
another aspect, the AP 110 may respond to the request message 701
with a frame (e.g., ACK or CTX with a special indication) that
acknowledges the reception of the request message 701 but does not
grant an immediate UL-MU-MIMO TXOP. In another aspect, the AP 110
may respond with a frame that acknowledges the reception of the
request message 701, does not grant an immediate UL-MU-MIMO TXOP,
but grants a delayed UL-MU-MIMO TXOP and may identify the time that
the TXOP is granted. In this embodiment, the AP 110 may send a CTX
message 402 to start the UL-MU-MIMO at the granted time.
[0066] In another aspect, the AP 110 may respond to the request
message 701 with an ACK or other response signal which does not
grant the user terminal 120 an UL-MU-MIMO transmission but
indicates that the user terminal 120 shall wait for a time (T)
before attempting another transmission (e.g., sending another
request message). In this aspect the time (T) may be indicated by
the AP 110 in the setup phase or in the response signal. In another
aspect an AP 110 and a user terminal 120 may agree on a time which
the user terminal 120 may transmit a request message 701 or any
other request for a UL-MU-MIMO TXOP.
[0067] In another operation mode, user terminals 120 may transmit
request messages 701 for UL-MU-MIMO transmissions 410 in accordance
with regular contention protocol. In another aspect, the contention
parameters for user terminals 120 using UL-MU-MIMO are set to a
different value than for other user terminals that are not using
the UL-MU-MIMO feature. In this embodiment, the AP 110 may indicate
the value of the contention parameters in a beacon, in an
association response or through a management frame. In another
aspect, the AP 110 may provide a delay timer that prevents a user
terminal 120 from transmitting for a certain amount of time after
each successful UL-MU-MIMO TXOP or after each request message 701.
The timer may be restarted after each successful UL-MU-MIMO TXOP.
In one aspect, the AP 110 may indicate the delay timer to user
terminals 120 in the setup phase or the delay timer may be
different for each user terminal 120. In another aspect, the AP 110
may indicate the delay timer in the CTX message 402 or the delay
timer may be dependent on the order of the user terminals 120 in
the CTX message 402, and may be different for each terminal.
[0068] In another operational mode, the AP 110 may indicate a time
interval during which the user terminals 120 are allowed to
transmit a UL-MU-MIMO transmission. In one aspect, the AP 110
indicates a time interval to the user terminals 120 during which
the user terminals are allowed to send a request message 701. In
this aspect, the user terminals 120 may use regular contention
protocol. In another aspect, the user terminals may not initiate a
UL-MU-MIMO transmission during the time interval but the AP 110 may
send a CTX or other message to the user terminals to initiate the
UL-MU-MIMO transmission.
[0069] FIG. 8 is a message timing diagram 800 showing multi-user
uplink communication. The message exchange shows communication of
wireless messages between an AP 110 and three user terminals
120A-C. The message exchange may indicate that each of the user
terminals 120A-C may transmit a request message (REQ) 802A-C to the
AP 110 requesting a UL-MU-MIMO TXOP. As described above, each of
the request messages 802A-C may indicate that the transmitting user
terminal 120A-C has data available to be transmitted to the AP
110.
[0070] After receiving each of request messages 802A-C, the AP 110
may respond with a message indicating that the AP 110 has received
each of the request messages 802A-C from the user terminals 120A-C.
As shown in FIG. 8, the AP 110 may transmit ACK messages 803A-C in
response to each of the request messages 802A-C. In some
embodiments, the AP 110 may transmit a trigger frame (TF) message
(e.g., a CTX message) indicating that each of the request messages
802A-C has been received but that the AP 110 has not granted a
transmission opportunity for the user terminals 120A-C to uplink
data. In FIG. 8, after sending the last ACK message 803C, the AP
110 may transmit a TF message 804. In some aspects, the TF message
804 is transmitted to at least the user terminals 120A-C. In some
aspects, the TF message 804 is a broadcast message. The TF message
804 may indicate which user terminals are granted permission to
transmit data to the AP 110 during a transmission opportunity. The
TF message 804 may also indicate a starting time of the
transmission opportunity and a duration of the transmission
opportunity. For example, the TF message 804 may indicate that the
user terminals 120A-C should set their network allocation vectors
to be consistent with NAV 812.
[0071] At a time indicated by the TF message 804, the three user
terminals 120A-C transmit data 806A-C to the AP 110. The data
806a-c are transmitted at least partially concurrently during the
transmission opportunity. The transmissions of data 806A-C may
utilize uplink multi-user multiple input, multiple output
transmissions (UL-MU-MIMO) or uplink frequency division multiple
access (UL-FDMA).
[0072] In some aspects, user terminals 120A-C may transmit padded
data such that the transmissions of each user terminal transmitting
during a transmission opportunity are of equal duration or
approximately equal duration. In the message exchange of FIG. 8,
the user terminal 120A may transmit pad data 808A, the user
terminal 120C may not transmit pad data, and the user terminal 120C
may transmit pad data 808c. The transmission of pad data ensures
that the transmissions from each of the UTs 120A-C complete at
approximately the same time. This may provide for a more equalized
transmission power over the entire duration of the transmission,
thereby optimizing AP 110 receiver efficiencies.
[0073] After the AP 110 receives the data transmissions 806A-C from
the user terminals 120A-C, the AP 110 may transmit acknowledgment
messages 810A-C to each of the user terminals 120A-C. In some
aspects, the acknowledgments messages 810A-C may be transmitted at
least partially concurrently using either DL-MU-MIMO or
DL-FDMA.
[0074] FIG. 9 shows a diagram of an example of a CTX frame 900
format. The CTX frame 900 may be configured as a trigger frame. In
this embodiment, the CTX frame 900 is a control frame that includes
a frame control (FC) field 905, a duration field 910, a receiver
address field 914, a transmitter address (TA) field 915, a control
(CTRL) field 920, a PPDU duration field 925, a UT info field 930,
and a frame check sequence (FCS) field 980. The FC field 905
indicates a control subtype or an extension subtype. The duration
field 910 indicates to any receiver of the CTX frame 900 to set the
network allocation vector (NAV). In some embodiments the RA 914
field identifies a group of UTs through a multicast MAC address.
The TA field 915 indicates the transmitter address or a BSSID. The
CTRL field 920 is a generic field that may include information
regarding the format of the remaining portion of the frame (e.g.,
the number of UT info fields and the presence or absence of any
subfields within a UT info field), indications for rate adaptation
for the user terminals 120, indication of allowed TID, and
indication that a CTS must be sent immediately following the CTX
frame 900. The CTRL field 920 may also indicate if the CTX frame
900 is being used for UL-MU-MIMO or for UL FDMA or both, indicating
whether a Nss or Tone allocation field is present in the UT Info
field 930. Alternatively, the indication of whether the CTX is for
UL-MU-MIMO or for UL FDMA can be based on the value of the subtype.
Note that UL-MU-MIMO and UL FDMA operations can be jointly
performed by specifying to a UT both the spatial streams to be used
and the channel to be used, in which case both fields are present
in the CTX; in this case, the Nss indication is referred to a
specific tone allocation. The PPDU duration 925 field indicates an
uplink duration for the following uplink transmission (e.g.,
UL-MU-MIMO PPDU). The AP 110 may determine the duration of the
following Mu-MIMO PPDU that the user terminals 120 are allowed to
send based on estimated TX time fields received in at least one
message requesting to transmit uplink data from the user terminals
120. The UT Info 930 field contains information regarding a
particular UT and may include a per-user terminal 120 set of
information (see the UT Info 1 field 930 through the UT Info N
field 975). The UT Info 930 field may include an AID or MAC address
field 932 which identifies a user terminal, a number of spatial
streams field (Nss) 935 field which indicates the number of spatial
streams a user terminal may use (e.g., in a UL-MU-MIMO system), a
Time Adjustment 936 field which indicates a time that a UT should
adjust its transmission compared to the reception of a trigger
frame (the CTX in this case), a Power Adjustment 938 field which
indicates a power backoff value a UT should take from a declared
transmit power, a Tone Allocation 940 field which indicates the
tones or frequencies a UT may use (in a UL-FDMA system), an Allowed
TID 942 field which indicates the allowable TID, an Allowed TX Mode
944 field which indicates the allowed TX modes, and a MCS 946 field
which indicates the MCS the UT should use. A user terminal 120
receiving a CTX with a Allowed TID 942 indication may be allowed to
transmit data only of that TID, data of the same or higher TID,
data of the same or lower TID, any data, or only data of that TID
first, then if no data is available, data of other TIDs. The FCS
980 field indicates the carries an FCS value used for error
detection of the CTX frame 900.
[0075] FIG. 10 shows a diagram of a request message 701 sent by a
user terminal 120 to request transmission of uplink data. The
request message 701 may comprise a request to transmit uplink data
1010. The request to transmit uplink data 1010 may comprise a
request for a UL-MU-MIMO TXOP. The request to transmit uplink data
1010 may comprise a frame indicating to the AP 110 that the user
terminal 120 has uplink data buffered to send. For example, the
request to transmit uplink data 1010 may comprise an RTS, PS-poll,
QoS null, data, or management frame set to indicate more data. In
some embodiments, a data frame or QoS Null frame may have bits 8-15
of the QoS control frame set to indicate more data. The user
terminal 120 and the AP 110 may determine during setup which frames
may indicate the request to transmit uplink data 1010. In other
embodiments, the user terminal 120 may send single user uplink data
and may indicate a request for an UL-MU-MIMO TXOP by setting bits
in the QoS control frame of its data packet.
[0076] The request message 701 may also comprise requested
operational parameters 1020 for transmitting uplink data. The
requested operational parameters 1020 may comprise operational
parameters for the user terminal 120 to employ for UL-MU-MIMO
transmissions. For example, the requested operational parameters
1020 may indicate an operating mode for when the user terminal 120
may transmit a request message 701, an estimated transmission time
for the uplink data, a buffer status indicating the number of bytes
pending for transmission, management information, user terminal
operating modes, a contention parameter, a number of spatial
streams the user terminal 120 may employ for uplink data
transmission, a time adjustment compared to the reception of the
trigger frame for the uplink transmission, a power backoff value
for the user terminal 120 to take from a declared transmit power,
tones, frequencies, or channels, for the user terminal 120 to
employ in transmission, an allowable TID, allowed TX modes, an MCS
that the user terminal 120 may employ for uplink transmissions,
transmission power parameters, and per TID queue information. In
one embodiment, the request to transmit uplink data 1010 may
comprise a QoS null frame and the requested operational parameters
1020 may include transmission power information and per TID queue
information which may be inserted in two bytes of a sequence
control and a QoS control field of the QoS null frame. The request
message 701 may also comprise a request-to-transmit (RTX) frame
specifically formatted to contain the request to transmit uplink
data 1010 and the requested operating parameters 1020 as further
described below with reference to FIG. 11.
[0077] As described above, the AP 110 may send the trigger frame
(e.g., CTX message 402) in response to receiving the request
message 701 from the user terminal 120. The trigger frame may
comprise operational parameters for the user terminal 120 to employ
for uplink transmissions. The AP 110 may determine the operational
parameters indicated in the trigger frame based on the requested
operational parameters 1020 received from the user terminal 120. In
some embodiments, before an UL-MU-MIMO communication can take
place, an AP 110 may collect information from the user terminals
120 that are participating in the UL-MU-MIMO communication. The AP
110 may optimize the collection of information from the user
terminals 120 by scheduling the UL transmissions from the user
terminals 120.
[0078] FIG. 11 shows a diagram of a request-to-transmit (RTX) frame
1100. The RTX frame 1100 may include a frame control (FC) field
1110, an optional duration field 1115, a transmitter
address/allocation identifier (TA/AID) field 1120, a receiver
address/basic service set identifier (RA/BSSID) field 1125, a TID
field 1130, an estimated transmission (TX) time field 1135, a
buffer status field 140, a UT operating mode field 1145, and a TX
power field 1150. The FC field 1110 may indicate a control subtype
or an extension subtype. The duration field 1115 may indicate to
any receiver of the RTX frame 1100 to set the network allocation
vector (NAV). In one aspect, the RTX frame 1100 may not have a
duration field 1115. The TA/AID field 1120 may indicate a source
address, which may be an AID or a full MAC address. The RA/BSSID
field 1125 may indicate the RA or BSSID. In one aspect, the RTX
frame 1100 may not contain a RA/BSSID field 1125. The TID field
1130 may indicate an access category (AC) for which a user terminal
has data. The estimated TX time field 1135 may indicate a time
requested for the uplink transmission (e.g., UL-TXOP) based on an
amount of time required for a user terminal 120 to send all the
data in its buffer at the current planned MCS. The buffer status
field 1140 may indicate a number of bytes pending at the user
terminal 120 for uplink transmission. The UT operating mode field
1145 may indicate set management information or operating modes for
the user terminal 120. The TX power field 1150 may indicate the
power at which the RTX frame 1100 is being transmitted and may be
used by the AP 110 to estimate the link quality and adapt the power
backoff indication in a CTX frame.
[0079] In other embodiments, the RTX frame 1100 may comprise fields
indicating a contention parameter, a number of spatial streams, a
time adjustment for the uplink transmission, a power backoff value,
tones, frequencies, or channels, for transmission, an allowable
TID, allowed TX modes, an MCS, transmission power parameters, or
per TID queue information as discussed above with reference to the
requested operational parameters 1020 of FIG. 10. In other
embodiments, the RTX frame 1100 may further include any parameter
that a user terminal 120 may use for transmitting uplink data.
[0080] FIG. 12 shows a flow chart 1200 of a method for requesting
transmission of uplink data. At block 201, the method may transmit
a first wireless message comprising a request for a first user
terminal to transmit uplink data and an indication of at least one
requested operational parameter. At block 1202, the method may
receive a second wireless message indicating whether a plurality of
user terminals including the first user terminal is selected to
transmit uplink data. The first message may be received from an
access point in response to the first wireless message. The second
wireless message may indicate at least one operational parameter
for transmission of uplink data based on the at least one requested
operational parameter.
[0081] 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.
[0082] 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.
[0083] 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.
[0084] The various operations of methods described above may 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 may be performed by corresponding functional means
capable of performing the operations.
[0085] The various illustrative logical blocks, modules and
circuits described in connection with the present disclosure may be
implemented or performed with a general purpose processor, a
digital signal processor (DSP), an application specific integrated
circuit (ASIC), a field programmable gate array 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 may be a microprocessor, but in the alternative,
the processor may be any commercially available processor,
controller, microcontroller or state machine. A processor may also
be implemented as a combination of computing devices, e.g., a
combination of a DSP and a microprocessor, a plurality of
microprocessors, one or more microprocessors in conjunction with a
DSP core, or any other such configuration.
[0086] In one or more 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. Thus, in some aspects computer readable medium may comprise
non-transitory computer readable medium (e.g., tangible media). In
addition, in some aspects computer readable medium may comprise
transitory computer readable medium (e.g., a signal). Combinations
of the above should also be included within the scope of
computer-readable media.
[0087] The methods disclosed herein comprise one or more steps or
actions for achieving the described method. The method steps and/or
actions may be interchanged with one another without departing from
the scope of the claims. In other words, unless a specific order of
steps or actions is specified, the order and/or use of specific
steps and/or actions may be modified without departing from the
scope of the claims.
[0088] 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.
[0089] While the foregoing is directed to aspects of the present
disclosure, other and further aspects of the disclosure may be
devised without departing from the basic scope thereof, and the
scope thereof is determined by the claims that follow.
* * * * *