U.S. patent application number 16/544312 was filed with the patent office on 2019-12-05 for beamforming training in orthogonal frequency division multiple access (ofdma) communication systems.
The applicant listed for this patent is Marvell World Trade Ltd.. Invention is credited to Liwen CHU, Jinjing JIANG, Hui-Ling LOU, Yakun SUN, Lei WANG, Hongyuan ZHANG.
Application Number | 20190373583 16/544312 |
Document ID | / |
Family ID | 56798482 |
Filed Date | 2019-12-05 |
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United States Patent
Application |
20190373583 |
Kind Code |
A1 |
CHU; Liwen ; et al. |
December 5, 2019 |
BEAMFORMING TRAINING IN ORTHOGONAL FREQUENCY DIVISION MULTIPLE
ACCESS (OFDMA) COMMUNICATION SYSTEMS
Abstract
A beamforming training packet is transmitted from a first
communication device to multiple second communication devices. A
trigger frame is generated at the first communication device to
trigger an uplink orthogonal frequency division multiple access
(OFDMA) transmission of beamforming training feedback from at least
some of the multiple second communication devices. After
transmission of the beamforming training packet by the first
communication device, the trigger frame is transmitted to the at
least some of the multiple communication devices. The uplink OFDMA
transmission is then received at the first communication device.
The uplink OFDMA transmission includes respective beamforming
training feedback packets generated based on the beamforming
training packet by respective ones of the at least some of the
multiple second communication devices. The respective beamforming
training feedback packets are simultaneously transmitted by the at
least some of the multiple second communication devices.
Inventors: |
CHU; Liwen; (San Ramon,
CA) ; ZHANG; Hongyuan; (Fremont, CA) ; WANG;
Lei; (San Diego, CA) ; SUN; Yakun; (San Jose,
CA) ; JIANG; Jinjing; (San Jose, CA) ; LOU;
Hui-Ling; (Sunnyvale, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Marvell World Trade Ltd. |
St. Michael |
|
BB |
|
|
Family ID: |
56798482 |
Appl. No.: |
16/544312 |
Filed: |
August 19, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15144543 |
May 2, 2016 |
10390328 |
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16544312 |
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14961380 |
Dec 7, 2015 |
10334571 |
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15144543 |
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62255822 |
Nov 16, 2015 |
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62244283 |
Oct 21, 2015 |
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62204164 |
Aug 12, 2015 |
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62156069 |
May 1, 2015 |
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62112894 |
Feb 6, 2015 |
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62112528 |
Feb 5, 2015 |
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62088257 |
Dec 5, 2014 |
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62156069 |
May 1, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L 27/2602 20130101;
H04W 72/005 20130101; H04L 5/0007 20130101; H04W 72/0413 20130101;
H04L 5/0037 20130101; H04W 4/06 20130101; H04L 12/1886 20130101;
H04W 84/12 20130101; H04L 5/005 20130101; H04L 5/0057 20130101;
H04L 5/0023 20130101; H04W 16/28 20130101 |
International
Class: |
H04W 72/00 20060101
H04W072/00; H04L 5/00 20060101 H04L005/00; H04L 12/18 20060101
H04L012/18; H04W 4/06 20060101 H04W004/06; H04W 16/28 20060101
H04W016/28; H04W 72/04 20060101 H04W072/04; H04W 84/12 20060101
H04W084/12; H04L 27/26 20060101 H04L027/26 |
Claims
1. A method for beamforming training in a wireless communication
network, the method comprising: transmitting, from a first
communication device, a transmission to multiple second
communication devices, wherein the transmission indicates that the
first communication device will subsequently transmit a null data
packet (NDP), wherein the multiple second communication devices
include i) a plurality of non-legacy second communication devices
and ii) a legacy second communication device, wherein the
transmission includes an NDP announcement frame that includes
multiple per-station information fields for indicating respective
second communication devices that are to provide feedback in
response to the NDP, wherein the multiple per-station information
fields are arranged in an order, wherein a first-occurring
per-station information field in the order is set to indicate an
address that has not been allocated to any communication devices in
the wireless communication network, and wherein another per-station
information field after the first-occurring per-station information
field is set to indicate an address of the legacy second
communication device; transmitting, from the first communication
device, the NDP; generating, at the first communication device, a
trigger frame to trigger an uplink orthogonal frequency division
multiple access (OFDMA) transmission of beamforming training
feedback from at least some non-legacy second communication devices
among the plurality of non-legacy second communication devices;
transmitting, with the first communication device and after
transmission of the NDP by the first communication device, the
trigger frame to the at least some non-legacy second communication
devices among the plurality of non-legacy second communication
devices; receiving, at the first communication device, the uplink
OFDMA transmission, wherein the uplink OFDMA transmission includes
respective beamforming training feedback packets generated based on
the NDP by respective ones of the at least some non-legacy second
communication devices among the plurality of non-legacy second
communication devices, and wherein the respective beamforming
training feedback packets are simultaneously transmitted by the at
least some non-legacy second communication devices among the
plurality of non-legacy second communication devices; and after
receiving the uplink OFDMA transmission, transmitting a polling
frame to trigger transmission of beamforming training feedback,
corresponding to the NDP, from the legacy second communication
device.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/144,543, now U.S. Pat. No. 10,390,328,
entitled "Beamforming Training in Orthogonal Frequency Division
Multiple Access (OFDMA) Communication Systems," filed on May 2,
2016, which is a continuation-in-part of U.S. patent application
Ser. No. 14/961,380, now U.S. Pat. No. 10,334,571, entitled
"Trigger Frame Format for Orthogonal Frequency Division Multiple
Access (OFDMA) communication," filed on Dec. 7, 2015, which claims
the benefit of U.S. Provisional Patent Application Nos.:
62/088,257, entitled "SYNC Design," filed on Dec. 5, 2014;
62/112,528, entitled "SYNC Design," filed on Feb. 5, 2015;
62/112,894, entitled "SYNC Design," filed on Feb. 6, 2015;
62/156,069, entitled "Beamforming Feedback per OFDMA," filed on May
1, 2015; No. 62/204,164, entitled "SYNC (Trigger Frame) Design,"
filed on Aug. 12, 2015; 62/244,283, entitled "OFDMA Beamforming
Feedback," filed on Oct. 21, 2015; and 62/255,822, entitled "DL
OFDMA with Broadcast RU," filed on Nov. 16, 2015. Additionally,
U.S. patent application Ser. No. 15/144,543 claims the benefit of
U.S. Provisional Patent Application No. 62/156,069, entitled
"Beamforming Feedback per OFDMA," filed on May 1, 2015. All of the
applications referenced above are hereby incorporated by reference
herein in their entireties.
[0002] Additionally, the present application is related to U.S.
patent application Ser. No. 14/961,635, now U.S. Pat. No.
10,375,679, entitled "Trigger Frame Format for Orthogonal Frequency
Division Multiple Access (OFDMA) communication," filed on Dec. 7,
2015, which is incorporated by reference herein in its
entirety.
FIELD OF THE DISCLOSURE
[0003] The present disclosure relates generally to communication
networks and, more particularly, to wireless local area networks
that utilize orthogonal frequency division multiplexing (OFDM).
BACKGROUND
[0004] When operating in an infrastructure mode, wireless local
area networks (WLANs) typically include an access point (AP) and
one or more client stations. WLANs have evolved rapidly over the
past decade. Development of WLAN standards such as the Institute
for Electrical and Electronics Engineers (IEEE) 802.11a, 802.11b,
802.11g, and 802.11n Standards has improved single-user peak data
throughput. For example, the IEEE 802.11b Standard specifies a
single-user peak throughput of 11 megabits per second (Mbps), the
IEEE 802.11a and 802.11g Standards specify a single-user peak
throughput of 54 Mbps, the IEEE 802.11n Standard specifies a
single-user peak throughput of 600 Mbps, and the IEEE 802.11ac
Standard specifies a single-user peak throughput in the gigabits
per second (Gbps) range. Future standards promise to provide even
greater throughputs, such as throughputs in the tens of Gbps
range.
[0005] These WLANs operate in either a unicast mode or a multicast
mode. In the unicast mode, the AP transmits information to one
client station at a time. In the multicast mode, the same
information is concurrently transmitted to a group of client
stations.
SUMMARY
[0006] In an embodiment, a method for beamforming training in a
wireless communication network includes transmitting, from a first
communication device, a beamforming training packet to multiple
second communication devices. The method also includes generating,
at the first communication device, a trigger frame to trigger an
uplink orthogonal frequency division multiple access (OFDMA)
transmission of beamforming training feedback from at least some of
the multiple second communication devices. The method further
includes transmitting, with the first communication device and
after transmission of the beamforming training packet by the first
communication device, the trigger frame to the at least some of the
multiple communication devices. The method additionally includes
receiving, at the first communication device, the uplink OFDMA
transmission, wherein the uplink OFDMA transmission includes
respective beamforming training feedback packets generated based on
the beamforming training packet by respective ones of the at least
some of the multiple second communication devices, and wherein the
respective beamforming training feedback packets are simultaneously
transmitted by the at least some of the multiple second
communication devices.
[0007] In another embodiment, an apparatus comprises a network
interface device having one or more integrated circuits configured
to transmit a beamforming training packet to multiple communication
devices. The one or more integrated circuits are also configured to
generate a trigger frame to trigger an uplink orthogonal frequency
division multiple access (OFDMA) transmission of beamforming
training feedback from at least some of the multiple communication
devices. The one or more integrated circuits are further configured
to, after transmission of the beamforming training, transmit the
trigger frame to the at least some of the multiple communication
devices. The one or more integrated circuits are additionally
configured to receive the uplink OFDMA transmission, wherein the
uplink OFDMA transmission includes respective beamforming training
feedback packets generated based on the beamforming training packet
by respective ones of the at least some of the multiple
communication devices, and wherein the respective beamforming
training feedback packets are simultaneously transmitted by the at
least some of the multiple communication devices.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a block diagram of an example wireless local area
network (WLAN), according to an embodiment.
[0009] FIG. 2 is a diagram of an example transmission sequence in a
WLAN, according to an embodiment;
[0010] FIG. 3 is a diagram of an example transmission sequence in a
WLAN, according to another embodiment;
[0011] FIG. 4 is a diagram of an example transmission sequence in a
WLAN, according to another embodiment;
[0012] FIG. 5A is a diagram of an announcement frame, according to
an embodiment;
[0013] FIG. 5B is a diagram of a frame body of an announcement
frame, according to an embodiment;
[0014] FIG. 5C is a diagram of per-station (per-STA) information
fields of an announcement frame, according to an embodiment;
[0015] FIG. 5D is a diagram of a per-STA information field,
according to an embodiment; and
[0016] FIG. 6 is a flow diagram of an example method for
beamforming training in a WLAN, according to an embodiment.
DETAILED DESCRIPTION
[0017] In embodiments described below, a wireless network device
such as an access point (AP) of a wireless local area network
(WLAN) simultaneously transmits data to multiple client stations
and/or receives data simultaneously transmitted by multiple client
stations. In some embodiments, the AP transmits data for the
multiple clients in different orthogonal frequency division
multiplexing (OFDM) sub-channels of an orthogonal frequency
division multiple access (OFDMA) transmission. Similarly, multiple
client stations simultaneously transmit data to the AP, in
particular, each client station transmits data in a different OFDM
sub-channel of an OFDMA transmission, in an embodiment. The AP is
configured to beamform or steer transmissions to client stations,
using channel information obtained from the client stations, in
some embodiments. For example, according to an embodiment, the AP
implements an explicit beamforming technique in which the AP
transmits a beamforming training packet, or a sounding packet, that
allows each of the multiple client stations to determine or
estimate characteristics of the channel (channel information)
between the AP and the client station. In an embodiment, the AP
also transmits a trigger frame to trigger multiple client stations
to simultaneously (e.g., in respective frequency portions) transmit
feedback that includes channel information, or steering information
(e.g., a steering matrix) determined based on the channel
information, to the AP. The AP transmits the trigger frame after
transmitting the beamforming training packet, in an embodiment.
Transmitting the trigger frame after transmitting the beamforming
training packet ensures that the client stations will have
sufficient amount of time to obtain channel information and to
generate feedback based on the channel information before the
feedback is to be transmitted by the client stations to the AP, in
an embodiment.
[0018] The AP is configured to operate with client stations
according to at least a first communication protocol. The first
communication protocol is sometimes referred to herein as "high
efficiency," "high efficiency WiFi," "high efficiency WLAN," "HE,"
"HEW," or 802.11ax communication protocol. The first communication
protocol supports OFDMA communication between the AP and the client
stations. In some embodiments, different client stations in the
vicinity of the AP are configured to operate according to one or
more other communication protocols that define operation in the
same frequency band as the HE communication protocol but with
generally lower data throughputs. The lower data throughput
communication protocols (e.g., IEEE 802.11a, IEEE 802.11n, and/or
IEEE 802.11ac) are collectively referred herein as "legacy"
communication protocols. The legacy communication protocols do not
support OFDMA communication, in an embodiment.
[0019] FIG. 1 is a block diagram of an example wireless local area
network (WLAN) 10, according to an embodiment. An AP 14 includes a
host processor 15 coupled to a network interface 16. In an
embodiment, the network interface 16 includes one or more integrate
circuits (ICs) configured to operate as discussed below. The
network interface 16 includes a medium access control (MAC)
processor 18 and a physical layer (PHY) processor 20. The PHY
processor 20 includes a plurality of transceivers 21, and the
transceivers 21 are coupled to a plurality of antennas 24. Although
three transceivers 21 and three antennas 24 are illustrated in FIG.
1, the AP 14 includes other suitable numbers (e.g., 1, 2, 4, 5,
etc.) of transceivers 21 and antennas 24 in other embodiments. In
some embodiments, the AP 14 includes a higher number of antennas 24
than transceivers 21, and antenna switching techniques are
utilized. In an embodiment, the MAC processor 18 is implemented on
at least a first IC, and the PHY processor 20 is implemented on at
least a second IC. In an embodiment, at least a portion of the MAC
processor 18 and at least a portion of the PHY processor 20 are
implemented on a single IC.
[0020] In various embodiments, the MAC processor 18 and the PHY
processor 20 are configured to operate according to a first
communication protocol (e.g., a High Efficiency, HE, or 802.11ax
communication protocol). In some embodiments, the MAC processor 18
and the PHY processor 20 are also configured to operate according
to a second communication protocol (e.g., according to the IEEE
802.11ac Standard). In yet another embodiment, the MAC processor 18
and the PHY processor 20 are additionally configured to operate
according to the second communication protocol, a third
communication protocol, and/or a fourth communication protocol
(e.g., according to the IEEE 802.11a Standard and/or the IEEE
802.11n Standard).
[0021] The WLAN 10 includes a plurality of client stations 25.
Although four client stations 25 are illustrated in FIG. 1, the
WLAN 10 includes other suitable numbers (e.g., 1, 2, 3, 5, 6, etc.)
of client stations 25 in various scenarios and embodiments. At
least one of the client stations 25 (e.g., client station 25-1) is
configured to operate at least according to the first communication
protocol. In some embodiments, at least one of the client stations
25 is not configured to operate according to the first
communication protocol but is configured to operate according to at
least one of the second communication protocol, the third
communication protocol, and/or the fourth communication protocol
(referred to herein as a "legacy client station").
[0022] The client station 25-1 includes a host processor 26 coupled
to a network interface 27. In an embodiment, the network interface
27 includes one or more ICs configured to operate as discussed
below. The network interface 27 includes a MAC processor 28 and a
PHY processor 29. The PHY processor 29 includes a plurality of
transceivers 30, and the transceivers 30 are coupled to a plurality
of antennas 34. Although three transceivers 30 and three antennas
34 are illustrated in FIG. 1, the client station 25-1 includes
other suitable numbers (e.g., 1, 2, 4, 5, etc.) of transceivers 30
and antennas 34 in other embodiments. In some embodiments, the
client station 25-1 includes a higher number of antennas 34 than
transceivers 30, and antenna switching techniques are utilized. In
an embodiment, the MAC processor 28 is implemented on at least a
first IC, and the PHY processor 29 is implemented on at least a
second IC. In an embodiment, at least a portion of the MAC
processor 28 and at least a portion of the PHY processor 29 are
implemented on a single IC.
[0023] According to an embodiment, the client station 25-4 is a
legacy client station, i.e., the client station 25-4 is not enabled
to receive and fully decode a data unit that is transmitted by the
AP 14 or another client station 25 according to the first
communication protocol. Similarly, according to an embodiment, the
legacy client station 25-4 is not enabled to transmit data units
according to the first communication protocol. On the other hand,
the legacy client station 25-4 is enabled to receive and fully
decode and transmit data units according to the second
communication protocol, the third communication protocol, and/or
the fourth communication protocol.
[0024] In an embodiment, one or both of the client stations 25-2
and 25-3, has a structure that is the same as or similar to the
client station 25-1. In an embodiment, the client station 25-4 has
a structure similar to the client station 25-1. In these
embodiments, the client stations 25 structured the same as or
similar to the client station 25-1 have the same or a different
number of transceivers and antennas. For example, the client
station 25-2 has only two transceivers and two antennas (not
shown), according to an embodiment.
[0025] In various embodiments, the MAC processor 18 and the PHY
processor 20 of the AP 14 are configured to generate data units
conforming to the first communication protocol and having formats
described herein. In an embodiment, the MAC processor 18 is
configured to implement MAC layer functions, including MAC layer
functions of the first communication protocol. In an embodiment,
the PHY processor 20 is configured to implement PHY functions,
including PHY functions of the first communication protocol. For
example, in an embodiment, the MAC processor 18 is configured to
generate MAC layer data units such as MPDUs, MAC control frames,
etc., and provide the MAC layer data units to the PHY processor 20.
In an embodiment, the PHY processor 20 is configured to receive MAC
layer data units from the MAC processor 18 and encapsulate the MAC
layer data units to generate PHY data units such as PHY protocol
data units (PPDUs) for transmission via the antennas 24. Similarly,
in an embodiment, the PHY processor 20 is configured to receive PHY
data units that were received via the antennas 24, and extract MAC
layer data units encapsulated within the PHY data units. In an
embodiment, the PHY processor 20 provides the extracted MAC layer
data units to the MAC processor 18, which processes the MAC layer
data units.
[0026] The transceiver(s) 21 is/are configured to transmit the
generated data units via the antenna(s) 24. Similarly, the
transceiver(s) 21 is/are configured to receive data units via the
antenna(s) 24. The MAC processor 18 and the PHY processor 20 of the
AP 14 are configured to process received data units conforming to
the first communication protocol and having formats described
hereinafter and to determine that such data units conform to the
first communication protocol, according to various embodiments.
[0027] In various embodiments, the MAC processor 28 and the PHY
processor 29 of the client device 25-1 are configured to generate
data units conforming to the first communication protocol and
having formats described herein. In an embodiment, the MAC
processor 28 is configured to implement MAC layer functions,
including MAC layer functions of the first communication protocol.
In an embodiment, the PHY processor 29 is configured to implement
PHY functions, including PHY functions of the first communication
protocol. For example, in an embodiment, the MAC processor 28 is
configured to generate MAC layer data units such as MPDUs, MAC
control frames, etc., and provide the MAC layer data units to the
PHY processor 29. In an embodiment, the PHY processor 29 is
configured to receive MAC layer data units from the MAC processor
28 and encapsulate the MAC layer data units to generate PHY data
units such as PPDUs for transmission via the antennas 34.
Similarly, in an embodiment, the PHY processor 29 is configured to
receive PHY data units that were received via the antennas 34, and
extract MAC layer data units encapsulated within the PHY data
units. In an embodiment, the PHY processor 29 provides the
extracted MAC layer data units to the MAC processor 28, which
processes the MAC layer data units.
[0028] The transceiver(s) 30 is/are configured to transmit the
generated data units via the antenna(s) 34. Similarly, the
transceiver(s) 30 is/are configured to receive data units via the
antenna(s) 34. The MAC processor 28 and the PHY processor 29 of the
client device 25-1 are configured to process received data units
conforming to the first communication protocol and having formats
described hereinafter and to determine that such data units conform
to the first communication protocol, according to various
embodiments.
[0029] FIG. 2 is a diagram of an example transmission sequence 200
in a WLAN, such as the WLAN 10 of FIG. 1, according to an
embodiment, in which an AP, such as the AP 14, performs beamforming
training with multiple client stations, such as multiple ones of
the client stations 25. The AP 14 transmits an announcement frame
202 to multiple client stations 25. The announcement frame 202 is a
downlink (DL) frame because the announcement frame 204 is
transmitted in the downlink direction from the AP 14 to the client
stations 25, in an embodiment. In an embodiment, the announcement
frame 202 identifies client stations 25 that are to participate in
the beamforming training. For example, the announcement frame 204
includes a respective identifier, such as an association identifier
(AID) or a partial AID (PAID), associated with each client station
25 that is an intended participant of the beamforming training, in
an embodiment. In an embodiment, the announcement frame 202 is a
null data packet announcement (NDPA) frame. In an embodiment, the
announcement frame 202 is a broadcast control frame that occupies
the entire bandwidth of the communication channel in which the
beamforming training is being performed. Thus, for example, in an
embodiment in which the beamforming training is being performed in
an 80 MHz-wide communication channel, the announcement frame 202
occupies an 80 MHz bandwidth. As another example, in an embodiment
in which the beamforming training is being performed in a 40
MHz-wide communication channel, the announcement frame 202 occupies
a 40 MHz bandwidth. In another embodiment, in which the beamforming
training is being performed in a communication channel of another
suitable width, the announcement frame 202 occupies a corresponding
bandwidth of the other suitable width.
[0030] After transmitting the announcement frame 202, the AP 14
transmits a beamforming training packet 204, such as a null data
packet (NDP), to sound the communication channel. The beamforming
training packet 204 is a DL packet, in an embodiment. The
beamforming training packet 204 occupies the bandwidth of the
communication channel in which the beamforming training is being
performed (i.e., the communication channel being sounded), in an
embodiment. The beamforming training packet 204 includes one or
more training signals, such as one or more training fields (e.g.,
long training fields (LTFs)), that allow each of the multiple
client stations 25 to estimate the channel between the AP 14 and
the client station 25, in an embodiment. In an embodiment, the AP
14 initiates transmission of the beamforming training packet 204
upon expiration of a predetermined time interval after the end of
transmission of the announcement frame 202. In an embodiment, the
predetermined time interval is a time interval corresponding to a
short inter-frame space (SIFS) defined by the first communication
protocol (e.g., IEEE 802.11ax) and/or by a legacy communication
protocol (e.g., the IEEE 802.11n/ac). In another embodiment, the
predetermined time interval is a suitable time interval different
from SIFS time interval. In another embodiment, the predetermined
time interval is a suitable time interval different from a SIFS
time interval.
[0031] After transmitting the beamforming training packet 204, the
AP 14 transmits a trigger frame 206 to trigger transmission of
beamforming feedback from at least some of the multiple client
stations 25, which are participating in the beamforming training,
to the AP 14. The trigger frame 206 is a DL frame, in an
embodiment. In an embodiment, the AP 14 initiates transmission of
the trigger frame 206 upon expiration of a predetermined time
interval after the end of transmission of the beamforming training
packet 204. In an embodiment, the predetermined time interval is a
time interval corresponding to the SIFS time interval defined by
the first communication protocol (e.g., IEEE 802.11ax) and/or by a
legacy communication protocol (e.g., the IEEE 802.11n/ac). In
another embodiment, the predetermined time interval is a suitable
time interval different from a SIFS time interval. In an
embodiment, the trigger frame 206 triggers the at least some of the
multiple client stations 25 to transmit respective feedback packets
simultaneously, using different frequency portions of an uplink
OFDMA transmission from the at least some of the client stations 25
to the AP 14. The trigger frame 206 includes one or more fields for
specifying one or more of i) a trigger type (e.g., that the trigger
frame 206 is a beamforming trigger, ii) one or more PHY parameters
that are to be utilized for transmission of feedback, iv) resource
unit allocations indicating which frequency portions correspond
with which client stations, etc., according to various embodiments.
The trigger frame 206 has a suitable format, such as a format
described in U.S. patent application Ser. No. 14/961,380 (Attorney
Docket No. MP6128) and/or U.S. patent application Ser. No.
14/961,635 (Attorney Docket No. MP6558), or another suitable
format, according to various embodiments.
[0032] In response to receiving the trigger frame 206, the at least
some of the multiple client stations 25 triggered by the trigger
frame 206 transmit beamforming feedback (e.g., feedback packets) in
an OFDMA transmission 208 to the AP 14. The OFDMA transmission 208
is an uplink (UL) transmission because OFDMA transmission 208 is
transmitted in the uplink direction from the client stations 25 to
the AP 14, in an embodiment. In an embodiment, each client station
25 initiates transmission of the feedback (e.g., a feedback packet)
upon expiration of a predetermined time interval, such as, for
example, a time interval corresponding to SIFS, after completion of
reception of the trigger frame 206. Because, in the transmission
sequence 200, the beamforming training packet 204 is transmitted by
the AP 14 before the trigger frame 206 is transmitted by the AP 14,
the client stations 25 have sufficient amount of time to perform
channel estimation based on the beamforming training packet 204,
and to generate the feedback based on the channel estimation, in an
embodiment. Accordingly, transmission of the feedback packets by
the client stations 25 as parts of the uplink OFDMA transmission
208 can begin upon expiration of a relatively short time interval
after the end of reception of the trigger frame 204 by the client
stations 25, such as the time interval corresponding to SIFS, in an
embodiment.
[0033] FIG. 3 is a diagram of an example transmission sequence 300
in a WLAN, such as the WLAN 10 of FIG. 1, according to an
embodiment, in which an AP, such as the AP 14, performs beamforming
training with multiple client stations, such as multiple ones of
the client stations 25. The transmission sequence 300 is similar to
the transmission sequence 200 of FIG. 2 except that the
announcement frame 202 in the transmission sequence 200 is replaced
with an announcement frame 302. Unlike the announcement frame 202
which occupies an entire bandwidth of the channel in which the
beamforming training is being performed, the announcement frame 302
is a duplicate frame that is duplicated in each of a plurality of
subchannels of the channel in which the beamforming training is
being performed. Thus, for example, in an embodiment in which the
beamforming training is being performed in an 80 MHz-wide
communication channel, the announcement frame 202 is duplicated in
each of four 20 MHz-wide subchannels of the 80 MHz-wide
communication channel, in an embodiment. As another example, in an
embodiment in which the beamforming training is being performed in
a 40 MHz-wide communication channel, the announcement frame 202 is
duplicated in each of two 20 MHz-wide subchannels of the 40
MHz-wide communication channel, in an embodiment. The announcement
frame 202 is duplicated in another suitable number of subchannels
of the communication channel in which the beamforming training is
being performed, in another embodiment.
[0034] In an embodiment, the announcement frame 302 has a format
the same as or similar to a beamforming announcement frame defined
by a legacy communication protocol, such as the IEEE 802-11n/ac
Standard. In an embodiment, a legacy communication device is
configured to receive, decode, and at least partially understand
information included in the announcement frame 302. Such format of
the announcement frame 302 allows one or more legacy client
stations, such as the legacy client station 25-4, along with one or
more non-legacy client stations, such as the client stations 25-1,
25-2, 15-3, to participate in the beamforming training, in an
embodiment. In an embodiment, however, such format of the
announcement frame 302 is used even when the plurality of client
stations that are intended participants of the beamforming training
being announced by the announcement frame does not include any
legacy client stations.
[0035] FIG. 4 is a diagram of an example transmission sequence 400
in a WLAN, such as the WLAN 10 of FIG. 1, according to an
embodiment, in which an AP, such as the AP 14, performs beamforming
training with multiple client stations, such as multiple ones of
the client stations 25. The transmission sequence 400 is similar to
the transmission sequence 300 of FIG. 3, except that the
transmission sequence 400 includes transmission of feedback by a
legacy client station, such as the legacy client station 25-4, in
an embodiment. For example, the multiple client stations 25 that
are participating in the beamforming training include a legacy
client station that is not configured to operate according to the
first communication protocol, in an embodiment. The legacy client
station is not configured for OFDMA communication, in an
embodiment.
[0036] In an embodiment, in the scenario illustrated in FIG. 4, the
announcement frame 302 identifies the legacy client station among
the multiple client stations that are intended participants in the
beamforming training being announced by the announcement frame 302.
The legacy client station is able to receive and decode the
announcement frame 302 and to determine, based on the announcement
frame 302, that the legacy client station is to participate in the
beamforming training being announced by the announcement frame 302,
in an embodiment. The legacy client station then receives the
beamforming training packet 204, transmitted by the AP 14 to the
multiple of client stations 25 that include the legacy client
station, and generates feedback based on the beamforming training
packet 204, in an embodiment.
[0037] The trigger frame 206 triggers at least some of the
non-legacy client stations to transmit feedback from at least some
of non-legacy client stations 25 of the plurality of client
stations 25 that are participating in the beamforming training
announced by the announcement frame 302, in an embodiment. After
receiving the uplink OFDMA transmission 208 that includes
respective feedback packets from the at least some of the
non-legacy client stations 25 triggered by the trigger frame 302,
the AP 14 transmits a poll frame 410. The poll frame 410 is a
duplicate frame that is duplicated in each of a plurality of
subchannels of the communication channel in which the beamforming
training is being performed, in an embodiment. In an embodiment,
the poll frame 410 has a beamforming feedback poll frame format
defined by the legacy communication protocol according to which the
legacy client station is configured to operate, such the IEEE
802.11n/ac Standard. In an embodiment, the AP 14 initiates
transmission of the poll frame 410 upon expiration of a
predetermined time interval, such as for example a time interval
corresponding to SIFS, after completion of reception of the OFDMA
transmission 208.
[0038] In response to receiving the poll frame 410, the legacy
client station transmits a feedback packet 412 to the AP 14. In an
embodiment, if more than one client legacy station is participating
in the beamforming training, the AP 14 transmits additional poll
frames after receiving the BF feedback 412 from the legacy client
station polled by the poll frame 410. Thus, for example, the
transmission sequence 400 includes one or more additional frame
exchanges 410, 412 via which the AP 14 obtains feedback from one or
more additional In an embodiment, the one or more additional poll
frames transmitted by the AP 14 trigger, one by one, trigger
additional legacy client station(s) to transmit feedback packets to
the AP 14 as defined by the by the legacy communication protocol
according to which the legacy client stations are configured to
operate, such the IEEE 802.11n/ac Standard.
[0039] FIG. 5A is a block diagram of an announcement frame 500,
according to an embodiment. In an embodiment, the announcement
frame 500 corresponds to the announcement frame 202 of FIG. 2 or
the announcement frame 302 of FIGS. 3 and 4. The announcement frame
500 includes a plurality of fields, including a frame control field
502, a duration/ID field 504, a first address field (e.g., a
receiver address (RA) field) 506, a second address field (e.g., a
transmitter address (TA) field) 508, a frame body field 510 and a
frame check field 512.
[0040] In an embodiment, the duration/ID field 504 includes an
indication of a duration until the end of a transmission
opportunity (TXOP) for the beamforming training initiated by the
announcement frame 500. The first address field (RA field) 506
includes a broadcast MAC address to indicate that the announcement
frame 500 is being broadcast to a plurality of client stations 25,
in an embodiment. The second address field (TA field) 508 includes
the address of the AP 14, in an embodiment. In an embodiment, the
frame body 510 includes identifies client station 25 that are to
participate in the beamforming training procedure, and also
indicates beamforming control information to the identified client
statins 25. Referring to FIG. 5B, in an embodiment, the frame body
510 includes a sounding token field 520 and per-STA information
fields 522. The frame body 510 also includes padding bits 524, in
some embodiments and scenarios. In an embodiment, padding bits 524
include one or more bits to ensure that the frame body 510 includes
a number of bits that is an integer multiple of an octet. In
another embodiment, padding bits 524 include one or more bits to
provide sufficient time for a receiving device (e.g., a client
station) to generate the uplink transmission being triggered by the
trigger frame 500. In some embodiments and/or scenarios, the frame
body 510 omits the padding bits 524.
[0041] FIG. 5C is a diagram of the per-STA information fields 522,
according to an embodiment. The per-STA information fields 522
includes a plurality of subfields 530, each subfield 530
corresponding to a particular client station or to a particular
client station 25, in an embodiment. As illustrated in FIG. 5D,
each per-STA information field 530 includes an STAID subfield 532
and a feedback control information subfield 534. In an embodiment,
the STAID subfield 532 identifies a particular client station 25
that is an intended participant in the beamforming training
procedure. In an embodiment, the STAID subfield 532 is the same as
or similar to the STAID subfield 702-4 described above with respect
to FIG. 7A. The feedback control information subfield 534 indicates
feedback information such as a feedback type, a beamforming
bandwidth (e.g., a bandwidth of the beamforming training packet
that follows the announcement frame 500), an Nc index that
indicates a number of columns in a feedback matrix to be provided
by the corresponding client station 25 to the AP 14, etc., in an
embodiment.
[0042] In an embodiment in which a legacy client station is a
participant in the beamforming training, such as the embodiment
described above with reference to FIG. 4, the legacy client station
is configured to automatically transmit feedback after reception of
a beamforming training packet, such as the beamforming training
packet 204, if the legacy client station is identified by the
per-STA information subfield 530-2 corresponding to STA0. For
example, the legacy communication protocol according to which the
legacy client station is configured to operate specifies that the
client station that is identified as STA0 in a beamforming
announcement frame should automatically transmit its feedback upon
expiration of a predetermined time interval (e.g., SIFS) after
reception of a beamforming training packet that follows the
beamforming announcement frame, in an embodiment. In an embodiment,
the AP 14 is configured to suppress automatic transmission of
feedback by the legacy client station to avoid collision of the
feedback with the trigger frame 206. For example, the AP 14 is
configured to set the per-STA information subfield 530-2
corresponding to STA0 to a reserved value (e.g., 0), or a value of
an STAID that is not associated with any client station 25 in the
WLAN 10, in an embodiment.
[0043] FIG. 6 is a flow diagram of an example method 600 for
beamforming training in a wireless communication network, according
to an embodiment. In some embodiments, the method 600 is
implemented by the AP 14 (FIG. 1). For example, in some
embodiments, the network interface device 16 (e.g., the PHY
processor 20 and/or the MAC processor 18) is configured to
implement the method 600. In other embodiments, another suitable
network interface device is configured to implement the method
600.
[0044] At block 602, a beamforming training packet is transmitted
to multiple communication devices. In an embodiment, the
beamforming training packet 204 of FIGS. 2, 3, 4 is transmitted. In
another embodiment, another suitable beamforming training packet is
transmitted. In an embodiment, the beamforming training packet
includes one or more training fields that allow the multiple
communication devices to obtain measures of respective
communication channels associated with the communication
devices.
[0045] At block 604, a trigger frame is generated. In an
embodiment, the trigger frame 206 of FIGS. 2, 3, 4, is generated.
In another embodiment, another suitable trigger frame is generated.
In an embodiment, the trigger frame is generated to trigger an
uplink OFDMA transmission from at least some of the multiple
communication devices. In an embodiment, the trigger frame includes
information to indicate respective frequency portions of the uplink
OFDMA transmission, the respective frequency portions corresponding
with respective ones of the at least some of the multiple
communication devices.
[0046] At block 606, after the beamforming training packet is
transmitted at block 602, the trigger frame generated at block 606
is transmitted to the at least some of the multiple communication
devices.
[0047] At block 608, the uplink OFDMA transmission is received. In
an embodiment, the uplink OFDMA transmission includes respective
beamforming training feedback packets from respective ones of the
at least some of the multiple communication devices. In an
embodiment, the respective beamforming training feedback packets
are simultaneously transmitted by the at least some of the multiple
communication devices. In an embodiment, the respective beamforming
feedback packets are transmitted, by the at least some of the
multiple communication device, in the respective frequency portions
corresponding with the at least some of the multiple communication
devices.
[0048] In an embodiment, each of the multiple communication devices
receives the beamforming training packet transmitted at block 602,
and generates beamforming feedback based on the received
beamforming training packet. Each of the at least some of the
multiple communication devices being triggered by the trigger frame
transmitted at block 606 receives the trigger frame and determines,
based on the received trigger frame, that the communication device
is being triggered to transmit the feedback generated based on the
beamforming training packet transmitted at block 602, in an
embodiment. In response to receiving the trigger frame, each of the
at least some of the multiple communication devices transmits the
feedback generated based on the beamforming training packet
transmitted at block 602, in an embodiment. In an embodiment,
because the trigger frame is transmitted at block 606 after the
beamforming training packet is transmitted at block 602, each of
the at least some multiple communication devices that is to
transmit the feedback in response to receiving the trigger frame at
block 606 has sufficient amount of time to generate the feedback
based on the beamforming training packet transmitted at block 602
and to transmit the feedback upon expiration of a relatively short
time interval after receiving the trigger frame transmitted at
block 606. For example, each of the at least some of the multiple
communication devices transmits the feedback upon expiration of a
time interval corresponding to SIFS after receiving the trigger
frame, in an embodiment.
[0049] In an embodiment, a method for beamforming training in a
wireless communication network includes transmitting, from a first
communication device, a beamforming training packet to multiple
second communication devices. The method also includes generating,
at the first communication device, a trigger frame to trigger an
uplink orthogonal frequency division multiple access (OFDMA)
transmission of beamforming training feedback from at least some of
the multiple second communication devices. The method further
includes transmitting, with the first communication device and
after transmission of the beamforming training packet by the first
communication device, the trigger frame to the at least some of the
multiple communication devices. The method additionally includes
receiving, at the first communication device, the uplink OFDMA
transmission, wherein the uplink OFDMA transmission includes
respective beamforming training feedback packets generated based on
the beamforming training packet by respective ones of the at least
some of the multiple second communication devices, and wherein the
respective beamforming training feedback packets are simultaneously
transmitted by the at least some of the multiple second
communication devices.
[0050] In other embodiments, the method includes any suitable
combination of one or more of the following features.
[0051] Transmitting the trigger frame comprises transmitting the
trigger frame upon expiration of a first predetermined time
interval after transmission of the beamforming training packet.
[0052] The first predetermined time interval corresponds to a short
inter-frame spacing (SIFS) time interval.
[0053] The trigger frame causes the second communication devices to
transmit the respective beamforming training feedback packets upon
expiration of a second predetermined time interval after reception
of the trigger frame by the second communication devices.
[0054] The second predetermined time interval corresponds to a
short inter-frame spacing (SIFS) time interval.
[0055] The trigger frame includes information to indicate
respective frequency portions of the uplink OFDMA transmission, the
respective frequency portions corresponding with respective ones of
the at least some of the multiple second communication devices.
[0056] The respective beamforming training feedback packets
simultaneously transmitted by the least some of the multiple second
communication devices are transmitted in the respective frequency
portions corresponding with the at least some of the multiple
second communication devices.
[0057] The method further comprises, prior to transmitting the
beamforming packet, transmitting, with the first communication
device, an announcement frame to the multiple second communication
devices, wherein the announcement frame identifies the multiple
second communication devices.
[0058] The announcement frame occupies an entire bandwidth of the
communication channel.
[0059] The announcement frame is duplicated in each of a plurality
of subchannels of the communication channel.
[0060] The multiple second communication devices include a legacy
communication device that is not configured for OFDMA
communication.
[0061] The method further comprises, after receiving the uplink
OFDMA transmission, transmitting a polling frame to trigger
transmission of feedback from the legacy communication device.
[0062] The method further comprises including, in the announcement
frame, an indication to suppress automatic feedback by the legacy
second communication device.
[0063] In another embodiment, an apparatus comprises a network
interface device having one or more integrated circuits configured
to transmit a beamforming training packet to multiple communication
devices. The one or more integrated circuits are also configured to
generate a trigger frame to trigger an uplink orthogonal frequency
division multiple access (OFDMA) transmission of beamforming
training feedback from at least some of the multiple communication
devices. The one or more integrated circuits are further configured
to, after transmission of the beamforming training, transmit the
trigger frame to the at least some of the multiple communication
devices. The one or more integrated circuits are additionally
configured to receive the uplink OFDMA transmission, wherein the
uplink OFDMA transmission includes respective beamforming training
feedback packets generated based on the beamforming training packet
by respective ones of the at least some of the multiple
communication devices, and wherein the respective beamforming
training feedback packets are simultaneously transmitted by the at
least some of the multiple communication devices.
[0064] In other embodiments, the apparatus includes any suitable
combination of one or more of the following features.
[0065] The one or more integrated circuits are configured to
transmit the trigger frame upon expiration of a first predetermined
time interval after transmission of the beamforming training
packet.
[0066] The first predetermined time interval corresponds to a short
inter-frame spacing (SIFS) time interval.
[0067] The trigger frame causes the second communication devices to
transmit the respective beamforming training feedback packets upon
expiration of a second predetermined time interval after reception
of the trigger frame by the multiple communication devices.
[0068] The second predetermined time interval corresponds to a
short inter-frame spacing (SIFS) time interval.
[0069] The trigger frame includes information to indicate
respective frequency portions of the uplink OFDMA transmission, the
respective frequency portions corresponding with respective ones of
the at least some of the multiple communication devices.
[0070] The respective beamforming training feedback packets
simultaneously transmitted by the least some of the multiple
communication devices are transmitted in the respective frequency
portions corresponding with the at least some of the multiple
communication devices.
[0071] The one or more integrated circuits are further configured
to, prior to transmitting the beamforming packet, transmit an
announcement frame to the multiple communication devices, wherein
the announcement frame identifies the multiple communication
devices.
[0072] The announcement frame occupies an entire bandwidth of the
communication channel.
[0073] The announcement frame is duplicated in each of a plurality
of subchannels of the communication channel.
[0074] The multiple communication devices include a legacy
communication device that is not configured for OFDMA
communication, and wherein the method further comprises, after
receiving the uplink OFDMA transmission, transmitting a polling
frame to trigger transmission of feedback from the legacy
communication device.
[0075] The one or more integrated circuits are further configured
to include in the announcement frame an indication to suppress
automatic feedback by the legacy second communication device.
[0076] At least some of the various blocks, operations, and
techniques described above may be implemented utilizing hardware, a
processor executing firmware instructions, a processor executing
software instructions, or any combination thereof. When implemented
utilizing a processor executing software or firmware instructions,
the software or firmware instructions may be stored in any computer
readable memory such as on a magnetic disk, an optical disk, or
other storage medium, in a RAM or ROM or flash memory, processor,
hard disk drive, optical disk drive, tape drive, etc. The software
or firmware instructions may include machine readable instructions
that, when executed by one or more processors, cause the one or
more processors to perform various acts.
[0077] When implemented in hardware, the hardware may comprise one
or more of discrete components, an integrated circuit, an
application-specific integrated circuit (ASIC), a programmable
logic device (PLD), etc.
[0078] While the present invention has been described with
reference to specific examples, which are intended to be
illustrative only and not to be limiting of the invention, changes,
additions and/or deletions may be made to the disclosed embodiments
without departing from the scope of the invention.
* * * * *