U.S. patent application number 15/337579 was filed with the patent office on 2017-02-16 for sub-channel allocation in orthogonal frequency division multiplex wlan.
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 | 20170047972 15/337579 |
Document ID | / |
Family ID | 53488473 |
Filed Date | 2017-02-16 |
United States Patent
Application |
20170047972 |
Kind Code |
A1 |
CHU; Liwen ; et al. |
February 16, 2017 |
SUB-CHANNEL ALLOCATION IN ORTHOGONAL FREQUENCY DIVISION MULTIPLEX
WLAN
Abstract
A first communication device receives one or more downlink
orthogonal frequency division multiplexing (OFDM) data units
transmitted by a second communication device via one or more
respective sub-channels of an OFDM communication channel. The first
communication device identifies the one or more sub-channels of the
OFDM communication channel on which the one or more downlink OFDMA
data units were transmitted, and determines whether each of the one
or more sub-channels on which the one or more downlink OFDMA data
units were transmitted is busy. The first communication device
generates an uplink OFDM data unit for each sub-channel determined
to be not busy, and transmits each of the uplink OFDM data units to
the second communication device via the corresponding
sub-channel.
Inventors: |
CHU; Liwen; (San Ramon,
CA) ; Wang; Lei; (San Diego, CA) ; Zhang;
Hongyuan; (Fremont, CA) ; Lou; Hui-Ling;
(Sunnyvale, CA) ; Sun; Yakun; (Sunnyvale, CA)
; Jiang; Jinjing; (San Jose, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Marvell World Trade Ltd. |
St. Michael |
|
BB |
|
|
Family ID: |
53488473 |
Appl. No.: |
15/337579 |
Filed: |
October 28, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14738521 |
Jun 12, 2015 |
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15337579 |
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62011332 |
Jun 12, 2014 |
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62044838 |
Sep 2, 2014 |
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62112959 |
Feb 6, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04B 7/0413 20130101;
H04W 74/02 20130101; H04W 72/0446 20130101; H04L 5/0037 20130101;
H04L 27/2656 20130101; H04W 84/12 20130101; H04L 5/0094 20130101;
H04L 5/0023 20130101; H04L 5/0055 20130101; H04B 7/0452 20130101;
H04L 5/0053 20130101; H04L 5/0007 20130101; H04W 72/0453
20130101 |
International
Class: |
H04B 7/04 20060101
H04B007/04; H04L 5/00 20060101 H04L005/00; H04L 27/26 20060101
H04L027/26 |
Claims
1. A method for simultaneous communication with multiple
communication devices in a wireless local area network, the method
comprising: receiving, at a first communication device, one or more
downlink orthogonal frequency division multiplexing (OFDM) data
units transmitted by a second communication device via one or more
respective sub-channels of an OFDM communication channel;
identifying, by the first communication device, the one or more
sub-channels of the OFDM communication channel on which the one or
more downlink OFDMA data units were transmitted; determining, by
the first communication device, whether each of the one or more
sub-channels on which the one or more downlink OFDMA data units
were transmitted is busy; generating, by the first communication
device, an uplink OFDM data unit for each sub-channel determined to
be not busy; and transmitting each of the uplink OFDM data units to
the second communication device via the corresponding
sub-channel.
2. The method of claim 1, wherein the one or more downlink OFDM
data units comprise synchronization frames and the one or more
uplink OFDM data units comprise one or more aggregate media access
control protocol data units (A-MPDU).
3. The method of claim 2, further comprising receiving, at the
first communication device via the sub-channels on which the one or
more uplink OFDM data units were transmitted, a block
acknowledgment that indicates receipt of the one or more A-MPDUs by
the second communication device.
4. The method of claim 3, further comprising receiving, at the
first communication device, a broadcast block acknowledgment having
i) a first device identifier corresponding to the first
communication device, ii) one or more other device identifiers
corresponding to one or more other communication devices, iii) one
or more bitmaps that indicate whether each of the one or more
A-MPDUs was successfully received by the second communication
device, and iv) one or more other bitmaps corresponding to the one
or more other communication devices.
5. The method of claim 2, wherein: the synchronization frame
includes a quality of service indicator, and generating the one or
more uplink OFDM data units comprises generating the one or more
A-MPDU to include only MPDUs having the corresponding quality of
service indicator.
6. The method of claim 1, wherein the one or more downlink OFDM
data units comprise one or more A-MPDUs and the one or more uplink
OFDM data units comprise one or more acknowledgments to the one or
more A-MPDU.
7. The method of claim 1, wherein the one or more uplink OFDM data
units are a portion of an orthogonal frequency division multiple
access (OFDMA) data unit.
8. The method of claim 1, wherein: the OFDM communication channel
comprises a MIMO communication channel and the one or more
sub-channels comprise one or more space time streams of the MIMO
communication channel; and receiving the one or more downlink OFDM
data units comprises receiving the one or more downlink OFDM data
unit via the corresponding space time stream.
9. An apparatus, comprising: a network interface device associated
with a first communication device, the network interface device
having one or more integrated circuit devices configured to
receive, from a second communication device, one or more downlink
orthogonal frequency division multiplexing (OFDM) data units
transmitted by a second communication device via one or more
respective sub-channels of an OFDM communication channel, identify
the one or more sub-channels of the OFDM communication channel on
which the one or more downlink OFDMA data units were transmitted,
determine whether each of the one or more sub-channels on which the
one or more downlink OFDMA data units were transmitted is busy,
generate an uplink OFDM data unit for each sub-channel determined
to be not busy, and transmit each of the uplink OFDM data units to
the second communication device via the corresponding
sub-channel.
10. The apparatus of claim 9, wherein the one or more downlink OFDM
data units comprise one or more synchronization frames and the one
or more uplink OFDM data units comprise one or more aggregate media
access control protocol data units (A-MPDU).
11. The apparatus of claim 10, wherein the one or more integrated
circuit devices are configured to receive, via the sub-channels on
which the one or more uplink OFDM data units were transmitted, a
block acknowledgment that indicates receipt of the one or more
A-MPDUs by the second communication device.
12. The apparatus of claim 11, wherein the one or more integrated
circuit devices are configured to receive a broadcast block
acknowledgment having i) a first device identifier corresponding to
the first communication device, ii) one or more other device
identifiers corresponding to one or more other communication
devices, iii) one or more bitmaps that indicate whether each of the
one or more A-MPDUs was successfully received by the second
communication device, and iv) one or more other bitmaps
corresponding to the one or more other communication devices.
13. The apparatus of claim 10, wherein: the synchronization frame
includes a quality of service indicator, and the one or more
integrated circuit devices are configured to generate the one or
more uplink OFDM data units comprises generating the one or more
A-MPDU to include only MPDUs having the corresponding quality of
service indicator.
14. The apparatus of claim 9, wherein the one or more downlink OFDM
data units comprise one or more A-MPDUs and the one or more uplink
OFDM data units comprise one or more acknowledgments to the one or
more A-MPDU.
15. The apparatus of claim 9, wherein the one or more uplink OFDM
data units are a portion of an orthogonal frequency division
multiple access (OFDMA) data unit.
16. The apparatus of claim 9, wherein: the OFDM communication
channel comprises a MIMO communication channel and the one or more
sub-channels comprise one or more space time streams of the MIMO
communication channel; and the one or more integrated circuit
devices are configured to receive the one or more downlink OFDM
data unit via the corresponding space time stream.
17. The apparatus of claim 9, wherein the network interface device
comprises one or more transceivers.
18. The apparatus of claim 17, further comprising: one or more
antennas coupled to the one or more transceivers.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/738,521, entitled "Sub-Channel Allocation
in Orthogonal Frequency Division Multiplex WLAN," filed on Jun. 12,
2015, which claims the benefit of the following provisional
applications: U.S. Provisional Patent Application No. 62/011,332,
entitled "Bandwidth/AC Selection and Acknowledge Indication in
OFDMA, UL MU MIMO," filed on Jun. 12, 2014, U.S. Provisional Patent
Application No. 62/044,838, entitled "Bandwidth/AC Selection and
Acknowledge Indication in OFDMA, UL MU MIMO," filed on Sep. 2,
2014, and U.S. Provisional Patent Application No. 62/112,959,
entitled "Bandwidth Selection and Acknowledge Indication in OFDMA,
UL MU MIMO," filed on Feb. 6, 2015. The disclosures of all of the
applications referenced above are incorporated herein by reference
in their entireties.
FIELD OF THE DISCLOSURE
[0002] The present disclosure relates generally to communication
networks and, more particularly, to wireless local area networks
that utilize orthogonal frequency division multiplexing (OFDM).
BACKGROUND
[0003] Wireless local area networks (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.
[0004] 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 transmitted to a group of client stations
concurrently.
SUMMARY
[0005] In an embodiment, a method for simultaneous communication
with multiple communication devices in a wireless local area
network includes allocating, by a first communication device,
respective sub-channels of an orthogonal frequency division
multiplexing (OFDM) communication channel to two or more second
communication devices for simultaneous OFDM transmission to the two
or more second communication devices, including allocating a first
sub-channel to a first one of the two or more second communication
devices and a second sub-channel to a second one of the two or more
second communication devices. The method also includes generating,
by the first communication device, respective downlink OFDM data
units for the two or more second communication devices using the
corresponding allocated sub-channels. The method includes
transmitting, by the first communication device, the downlink OFDM
data units to the two or more second communication devices using
the corresponding allocated sub-channels. The method also includes
receiving, at the first communication device, at least i) a first
uplink OFDM data unit transmitted by the first one of the two or
more second communication devices in response to the corresponding
downlink OFDM data unit and ii) a second uplink OFDM data unit
transmitted by the second one of the two or more second
communication devices in response to the corresponding downlink
OFDM data unit, wherein the first uplink OFDM data unit is
transmitted from the first one of the two or more second
communication devices via the first sub-channel allocated to the
first one of the two or more second communication devices and the
second uplink OFDM data unit is transmitted from the second one of
the two or more second communication devices via the second
sub-channel allocated to the second one of the two or more second
communication devices.
[0006] In another embodiment, a method for simultaneous
communication with multiple communication devices in a wireless
local area network includes receiving, at a first communication
device from a second communication device, a downlink orthogonal
frequency division multiplexing (OFDM) data unit via an OFDM
communication channel. The method also includes identifying, by the
first communication device, a sub-channel of the OFDM communication
channel on which the downlink OFDM data unit was transmitted by the
second communication device. The method includes generating, by the
first communication device in response to the downlink OFDM data
unit, an uplink OFDM data unit to be transmitted via the
sub-channel on which the downlink OFDM data unit was transmitted.
The method also includes automatically transmitting the uplink OFDM
data unit to the second communication device via the sub-channel on
which the downlink OFDM data unit was transmitted.
[0007] In an embodiment, a method for simultaneous communication
with multiple communication devices in a wireless local area
network includes receiving, at a first communication device, one or
more downlink orthogonal frequency division multiplexing (OFDM)
data units transmitted by a second communication device via one or
more respective sub-channels of an OFDM communication channel. The
method includes identifying, by the first communication device, the
one or more sub-channels of the OFDM communication channel on which
the one or more downlink OFDMA data units were transmitted. The
method also includes determining, by the first communication
device, whether each of the one or more sub-channels on which the
one or more downlink OFDMA data units were transmitted is busy. The
method includes generating, by the first communication device, an
uplink OFDM data unit for each sub-channel determined to be not
busy. The method also includes transmitting each of the uplink OFDM
data units to the second communication device via the corresponding
sub-channel.
[0008] In yet another embodiment, an apparatus comprises a network
interface device associated with a first communication device. The
network interface device includes one or more integrated circuit
devices configured to: receive, from a second communication device,
one or more downlink orthogonal frequency division multiplexing
(OFDM) data units transmitted by a second communication device via
one or more respective sub-channels of an OFDM communication
channel; identify the one or more sub-channels of the OFDM
communication channel on which the one or more downlink OFDMA data
units were transmitted; determine whether each of the one or more
sub-channels on which the one or more downlink OFDMA data units
were transmitted is busy; generate an uplink OFDM data unit for
each sub-channel determined to be not busy; and transmit each of
the uplink OFDM data units to the second communication device via
the corresponding sub-channel.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a block diagram of an example wireless local area
network (WLAN), according to an embodiment.
[0010] FIGS. 2A, 2B, and 2C are diagrams illustrating example
orthogonal frequency division multiplexing (OFDM) sub-channel
blocks for an 80 MHz communication channel, according to an
embodiment.
[0011] FIG. 3 is a diagram of an example orthogonal frequency
division multiple access (OFDMA) data unit, according to an
embodiment.
[0012] FIG. 4 is a diagram of an example OFDMA data unit, according
to another embodiment.
[0013] FIG. 5 is an example broadcast block acknowledgment field,
according to an embodiment.
[0014] FIG. 6 is diagram illustrating a frame exchange between an
AP and multiple client stations, according to an embodiment.
[0015] FIG. 7 is a diagram illustrating various acknowledgment
types for a transmission opportunity holder, according to an
embodiment.
[0016] FIG. 8 is a diagram illustrating a block acknowledgment
during a frame exchange for a TXOP holder, according to an
embodiment.
[0017] FIG. 9 is a frame exchange between an AP and a plurality of
client stations that includes an uplink transmission of data from
the plurality client stations to the AP, according to an
embodiment.
[0018] FIG. 10 is a frame exchange between an AP and a plurality of
client stations that includes uplink OFDMA transmission of data
from the plurality client stations to the AP, according to another
embodiment.
[0019] FIG. 11 is a frame exchange between an AP and a plurality of
client stations that includes uplink OFDMA transmission of data
from the plurality client stations to the AP, according to another
embodiment.
[0020] FIG. 12 is a frame exchange between an AP and a plurality of
client stations that includes uplink OFDMA transmission of data
from the plurality client stations to the AP, according to another
embodiment.
[0021] FIG. 13 is a frame exchange between an AP and a plurality of
client stations that includes uplink OFDMA transmission of data
from the plurality client stations the AP, according to an
embodiment.
[0022] FIG. 14 is a frame exchange between an AP and a plurality of
client stations that includes uplink OFDMA transmission of data
from the plurality client stations the AP, according to an
embodiment.
[0023] FIG. 15 is a frame exchange between an AP and a plurality of
client stations that includes uplink OFDMA transmission of data
from the plurality client stations the AP, according to an
embodiment.
[0024] FIG. 16 is a frame exchange between an AP and a plurality of
client stations that includes uplink OFDMA transmission of data
from the plurality client stations the AP, according to another
embodiment.
[0025] FIG. 17 is a frame exchange between an AP and a plurality of
client stations that includes downlink OFDMA transmission of data
from the AP to the plurality client stations, according to an
embodiment.
[0026] FIG. 18 is a frame exchange between an AP and a plurality of
client stations that includes downlink OFDMA transmission of data
from the AP to the plurality client stations, according to an
embodiment.
[0027] FIG. 19 is a frame exchange between an AP and a plurality of
client stations that includes downlink OFDMA transmission of data
from the AP to the plurality client stations, according to an
embodiment.
[0028] FIG. 20 is a frame exchange between an AP and a plurality of
client stations that includes downlink OFDMA transmission of data
from the AP to the plurality client stations, according to an
embodiment.
[0029] FIG. 21 is a frame exchange between an AP and a plurality of
client stations that includes downlink OFDMA transmission of data
from the AP to the plurality client stations, according to an
embodiment.
[0030] FIG. 22 is a frame exchange between an AP and a plurality of
client stations that includes uplink OFDMA transmission of data
with selected traffic identifiers, according to an embodiment.
[0031] FIG. 23 is a frame exchange between an AP and a plurality of
client stations that includes downlink OFDMA transmission of data
with selected traffic identifiers, according to an embodiment.
[0032] FIG. 24 is a frame exchange between an AP and a plurality of
client stations that includes both uplink OFDMA transmission of
data and downlink OFDMA transmission of data with selected traffic
identifiers, according to an embodiment.
[0033] FIG. 25 is a diagram illustrating example uplink OFDMA
parameters for an OFDMA group of client stations, and
communications between an AP and client stations of the OFDMA group
that occur during time periods defined by the OFDMA parameters,
according to an embodiment.
[0034] FIG. 26 is a flow diagram of an example method that is
implemented by an AP in a WLAN, according to an embodiment.
[0035] FIG. 27 is a flow diagram of another example method that is
implemented by an AP in a WLAN, according to another
embodiment.
[0036] FIG. 28 is a flow diagram of an example method for
simultaneous communication with multiple communication devices in a
wireless local area network, according to an embodiment.
DETAILED DESCRIPTION
[0037] In embodiments described below, a wireless network device
such as an access point (AP) of a wireless local area network
(WLAN) simultaneously transmits independent data streams to
multiple client stations and/or receives independent data streams
simultaneously transmitted by multiple client stations. In
particular, the AP transmits data for the multiple clients in
different sub-channels of an orthogonal frequency division
multiplexing (OFDM) communication channel, in various embodiments.
In an embodiment, the sub-channels indicate bandwidth in an
orthogonal frequency division multiple access (OFDMA) transmission,
in an embodiment. In another embodiment, the sub-channels are space
time streams of a multiuser multiple input, multiple output
(MU-MIMO) communication channel. Similarly, multiple client
stations simultaneously transmit data to the AP, in particular,
each client station transmits data in a different OFDM sub-channel,
in various embodiments.
[0038] 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 WiFi," "high efficiency WLAN," "HEW" communication
protocol, or 802.11ax communication protocol. In an embodiment, the
first communication protocol supports OFDMA communication between
the AP and the client stations. In an embodiment, the first
communication protocol supports MU-MIMO 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 HEW 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. In
another embodiment, the legacy communication protocols do not
support MU-MIMO communication.
[0039] In an embodiment, client stations that are configured to
operate according to the HEW communication protocol generally
support OFDMA communication and/or MU-MIMO communication initiated
by the AP. In some embodiments, client stations that are configured
to operate according to the HEW communication protocol optionally
support OFDMA communication and/or MU-MIMO communication initiated
by the client stations.
[0040] 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. The network
interface 16 includes a medium access control (MAC) processing unit
18 and a physical layer (PHY) processing unit 20. The PHY
processing unit 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 different numbers (e.g., 1, 2, 4, 5, etc.) of
transceivers 21 and antennas 24 in other embodiments.
[0041] The WLAN 10 includes a plurality of client stations 25.
Although four client stations 25 are illustrated in FIG. 1, the
WLAN 10 includes different numbers (e.g., 1, 2, 3, 5, 6, etc.) of
client stations 25 in various scenarios and embodiments. Two or
more of the client stations 25 are configured to receive
corresponding data streams that are transmitted simultaneously by
the AP 14. Additionally, two or more of the client stations 25 are
configured to transmit corresponding data streams to the AP 14 such
that the AP 14 simultaneously receives the data streams.
[0042] A client station 25-1 includes a host processor 26 coupled
to a network interface 27. The network interface 27 includes a MAC
processing unit 28 and a PHY processing unit 29. The PHY processing
unit 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 different numbers (e.g., 1, 2,
4, 5, etc.) of transceivers 30 and antennas 34 in other
embodiments.
[0043] In an embodiment, one or more of the client stations 25-2,
25-3, and 25-4 has a structure the same as or similar to the client
station 25-1. In these embodiments, the client stations 25
structured like 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.
[0044] According to an embodiment, the client station 25-4 is a
legacy client station that is not enabled to receive a data stream
that is simultaneously transmitted by the AP 14 with other
independent data streams as part of an OFDMA transmission or as
part of a MU-MIMO transmission to multiple client stations 25.
Similarly, according to an embodiment, the legacy client station
25-4 is not enabled to transmit a data stream that to the AP 14 as
part of OFDMA transmission or as part of a MU-MIMO transmission
from multiple client stations 25. According to an embodiment, the
legacy client station 25-4 includes a PHY processing unit that is
generally capable of receiving a data stream that is simultaneously
transmitted by the AP 14 with other independent data streams that
are intended for other client stations 25. But the legacy client
station 25-4 includes a MAC processing unit that is not enabled
with MAC layer functions that support receiving the data stream
that is simultaneously transmitted by the AP 14 with other
independent data streams that are intended for other client
stations 25. According to an embodiment, the legacy client station
25-4 includes a PHY processing unit that is generally capable of
transmitting a data stream to the AP 14 at the same time that other
client stations 25 transmit data to the AP 14. But the legacy
client station 25-4 includes a MAC processing unit that is not
enabled with MAC layer functions that support transmitting a data
stream to the AP 14 at the same time that other client stations 25
transmit data to the AP 14.
[0045] In an embodiment, the AP 14 and the client stations 25
contend for communication medium using carrier sense multiple
access with collision avoidance (CSMA/CA) protocol or another
suitable medium access protocol. Further, in an embodiment, the AP
14 or a client station 25 dynamically selects a bandwidth for a
transmission based on channels available for the transmission. In
an embodiment, communication between the AP 14 and a legacy client
station (e.g., the legacy client station 25-4) occur in a primary
channel of the WLAN 10, or in a wider channel that includes the
primary channel of the WLAN 10. For example, the legacy
communication protocol requires that each transmission includes the
primary channel, in an embodiment. On the other hand, communication
between the AP 14 and a non-legacy client station 25 (e.g., the
client station 25-1) can occur in one or more communication
channels that do not include the primary channel, in an embodiment.
For example, the non-legacy communication protocol, such as the HEW
communication protocol, allows communication between the AP and the
client stations to occur in a communication channel that does not
include the primary channel, in an embodiment.
[0046] In an embodiment, the AP 14 is configured to simultaneously
transmit different OFDM units to different client stations 25 by
forming an OFDMA data unit that includes the different OFDM data
units modulated in respective sub-channel blocks of the OFDMA data
unit. In an embodiment, the AP 14 allocates different sub-channels
to different client stations and forms the OFDMA data unit that
includes OFDM data units directed to by modulating the different
client stations in sub-channel blocks corresponding to the
sub-channels assigned to the client stations. In an embodiment,
when the one or more client stations include a legacy client
station, the AP assigns a channel that includes a primary channel
of the WLAN 10 to the legacy client station, and assigns one or
more non-primary communication channels of the WLAN 10 to one or
more non-legacy client stations. When the one or more client
stations do not include any legacy client stations, the AP assigns
the primary and the non-primary communication channels in any
suitable manner to the one or more client stations, in various
embodiments.
[0047] In an embodiment, the AP 14 is configured to simultaneously
transmit different OFDM units to different client stations 25 by
transmitting the different OFDM data units via different space time
streams of a MU-MIMO communication channel. In an embodiment, the
AP 14 allocates different sub-channels (i.e., space time streams)
to different client stations and forms the OFDM data units and
modulates the different OFDM data units to the space time streams
corresponding to the sub-channels assigned to the client stations.
In an embodiment, when the one or more client stations include a
legacy client station, the AP assigns a channel that includes a
primary channel of the WLAN 10 to the legacy client station, and
assigns one or more non-primary communication channels of the WLAN
10 to one or more non-legacy client stations. When the one or more
client stations do not include any legacy client stations, the AP
assigns the primary and the non-primary communication channels in
any suitable manner to the one or more client stations, in various
embodiments.
[0048] FIGS. 2A, 2B, and 2C are diagrams illustrating example OFDM
sub-channel blocks for an 80 MHz communication channel, according
to an embodiment. In FIG. 2A, the communication channel is
partitioned into four contiguous OFDM sub-channel blocks, each
having a bandwidth of 20 MHz. The OFDM sub-channel blocks include
independent data streams for four client stations. In FIG. 2B, the
communication channel is partitioned into two contiguous OFDM
sub-channel blocks, each having a bandwidth of 40 MHz. The OFDM
sub-channel blocks include independent data streams for two client
stations. In FIG. 2C, the communication channel is partitioned into
three contiguous OFDM sub-channel blocks. Two OFDM sub-channel
blocks each have a bandwidth of 20 MHz. The remaining OFDM
sub-channel block has a bandwidth of 40 MHz. The OFDM sub-channel
blocks include independent data streams for three client stations.
In some embodiments, a sub-channel has a bandwidth that is less
than 20 MHz, for example, 10 MHz, 2 MHz, or another suitable
bandwidth.
[0049] Although in FIGS. 2A, 2B, and 2C, the OFDM sub-channel
blocks are contiguous across the communication channel, in other
embodiments the OFDM sub-channel blocks are not contiguous across
the communication channel (i.e., there are one or more gaps between
the OFDM sub-channel blocks). In an embodiment, each gap is at
least as wide as one of the OFDM sub-channel blocks. In another
embodiment, at least one gap is less than the bandwidth of an OFDM
sub-channel block. In another embodiment, at least one gap is at
least as wide as 1 MHz. In an embodiment, different OFDM
sub-channel blocks are transmitted in different channels defined by
the IEEE 802.11a and/or 802.11n Standards. In one embodiment, the
AP includes a plurality of radios and different OFDM sub-channel
blocks are transmitted using different radios.
[0050] FIG. 3 is a diagram of an example OFDMA data unit 300,
according to an embodiment. The OFDMA data unit 300 includes a
plurality of OFDM data unit 302-1, 302-2 and 302-3. In an
embodiment, the AP 14 transmits the OFDM data units 302-1, 302-2,
302-3 to different client stations 25 via respective OFDM
sub-channels within the OFDMA data unit 300. In another embodiment,
different client stations 25 transmit respective OFDM data units
302-1, 302-2, 302-3 to the AP 14 in respective OFDM sub-channels
within the OFDMA data unit 300. In this embodiment, The AP 14
receives the OFDM data units 302-1, 302-2, 302-3 from the client
stations 25 via respective OFDM sub-channels of within the OFDMA
data unit 300, in this embodiment.
[0051] Each of the OFDM data units 302-1, 302-2, 302-3 conforms to
a communication protocol that defines OFDMA communication, such as
the HEW communication protocol, in an embodiment. In an embodiment
in which the OFDMA data unit 300 corresponds to a downlink OFDMA
data unit, the OFDMA data unit 300 is generated by the AP 14 such
that each OFDM data unit 302 is transmitted to a respective client
station 25 via a respective sub-channel of the WLAN 10 allocated
for downlink transmission of the OFDMA data unit 300 to the client
station. Similarly, an embodiment in which the OFDMA data unit 300
corresponds to an uplink OFDMA data unit, the AP 14 receives the
OFDM data units 302 via respective sub-channels of the WLAN 10
allocated for uplink transmission of the OFDM data units 302 from
the client stations, in an embodiment. For example, the OFDM data
unit 302-1 is transmitted via a first 20 MHZ sub-channel of the
WLAN 10, the OFDM data unit 302-2 is transmitted via a second 20
MHz sub-channel of the WLAN 10, and the OFDM data unit 302-3 is
transmitted via a 40 MHz sub-channel of the WLAN 10, in the
illustrated embodiment.
[0052] In an embodiment, each of the OFDM data units 302 includes a
preamble including one or more legacy short training fields (L-STF)
304, one or more legacy long training fields (L-LTF) 306, one or
more legacy signal fields (L-SIG) 308, one or more first high
efficiency WLAN signal field (HEW-SIG-A) 310, N HEW long training
fields (HEW-LTF) and a second HEW signal field (HEW-SIGB) 314.
Additionally, each OFDM data unit 302 includes a high efficiency
WLAN data portion (HEW-DATA) 318. In an embodiment, each L-LSF
field 306, each L-LTF field 308, each L-SIG field 310 and each
HEW-SIGA field 312 occupies a smallest bandwidth supported by the
WLAN 10 (e.g., 20 MHz). In an embodiment, if an OFDM data unit 302
occupies a bandwidth that is greater than the smallest bandwidth of
the WLAN 10, then each L-LSF field 306, each L-LTF field 308, each
L-SIG field 310 and each HEW-SIGA field 312 is duplicated in each
smallest bandwidth portion of the OFDM data unit 302 (e.g., in each
20 MHz portion of the data unit 302). On the other hand, each
HEW-STF field 312, each HEW-LTF field 314, each HEW-SIGB field 316
and each HEW data portion 318 occupies an entire bandwidth of the
corresponding OFDM data unit 302, in an embodiment. For example,
the OFDM data unit 302-3 occupies 40 MHz, wherein L-LSF field 306,
the L-LTF field 308, L-SIG field 310 and HEW-SIGA fields 312 is
duplicated in the upper and the lower 20 MHz bands of the OFDM data
unit 302-3, while each of the HEW-STF field 312, each of the
HEW-LTF fields 314, each of the HEW-SIGB field 316 and each of the
HEW data portion 318 occupies the entire 40 MHz bandwidth of the
data unit 302, in the illustrated embodiment.
[0053] In an embodiment, padding is used in one or more of the OFDM
data units 302 to equalize lengths of the OFDM data units 302.
Accordingly, the length of each of the OFDM data units 302
correspond to the length of the OFDMA data unit 302, in this
embodiment. Ensuring that the OFDM data units 302 are of equal
lengths synchronizes transmission of acknowledgment frames by
client stations 25 that receive the data units 302, in an
embodiment. In an embodiment, each of one or more of the OFDM data
units 302 is an aggregate MAC service data units (A-MPDU) (e.g., a
very high throughput (VHT) A-MPDU, an HEW MPDU, or another suitable
aggregated data unit), which is in turn included in a PHY protocol
data unit (PPDU). In another embodiment, each of one or more of the
OFDM data units 302 is a single MPDU (e.g., a VHT MPDU, an HEW
MPDU, or another suitable non-aggregated data unit) which is in
turn included in a PPDU. In an embodiment, padding (e.g.,
zero-padding) within one or more of the A-MPDUs 302 or single MPDUs
302 is used to equalize the lengths of the data units 302, and to
synchronize transmission of acknowledgement frames corresponding to
the OFDMA data unit 300.
[0054] FIG. 4 is a diagram of an example OFDMA data unit 350,
according to another embodiment. The OFDMA data unit 350 is similar
to the OFDMA data unit 300 of FIG. 3 except that the OFDMA data
unit 350 includes an OFDMA data unit 302-4 formatted according to a
legacy communication protocol that does not support OFDMA
communication (e.g., the IEEE 802.11ac Standard).
[0055] In an embodiment, the AP 14 forms OFDMA groups of client
stations 25, and informs the client stations 25 that the client
stations 25 are members of particular OFDMA groups. For example, in
an embodiment, the AP assigns a group number to an OFDMA group of
client stations 25, and transmits a management or a control frame
that signals the group ID number to the client stations 25 that
belong to the OFDMA group. For example, the management or control
frame includes the group ID number and a respective unique
identifier of each of the client stations 25 that belongs to the
group, in an embodiment. In an embodiment, the AP 14 allocates
respective OFDM sub-channels to client stations 25 that belong to
an OFDMA group, and provides channel allocation information to the
client stations 25 of the OFDMA group. In an embodiment, the AP 14
allocates respective OFDM sub-channels to client stations 25
dynamically without pre-defining an OFDMA group. The client
stations 25 of the OFDMA group subsequently receive data in the
respective OFDM sub-channels allocated to the client stations 25
when the data is transmitted to the client stations 25 in an OFDMA
transmission from the AP 14 to the client stations 25, in an
embodiment and/or scenario. In another embodiment and/or scenario,
the client stations 25 of the OFDMA group subsequently transmit
respective data as part of an OFDMA transmission to the AP 14 by
transmitting the data in the respective OFDM sub-channels allocated
to the client stations 25 by the AP 14.
[0056] FIG. 5 is an example broadcast block acknowledgment field
500, according to an embodiment. In an embodiment, the broadcast
block acknowledgment field 500 is included in an acknowledgment
frame that the AP 14 transmits to client stations 25 in response to
receipt of respective aggregate media access control protocol data
units (A-MPDUs) from the client stations 25. The broadcast block
acknowledgment field 500 includes a plurality of association
identifier (AID) subfields 502 and a corresponding plurality of
bitmap subfields 504. In an embodiment, the AID subfields 502
include as many subfields as there are client stations 25 assigned
to an OFDMA group and each of the client stations has a
corresponding bitmap subfield 504. In another embodiment, the AID
subfields 502 include as many subfields as there are client
stations 25 that have transmitted respective A-MPDUs prior to the
acknowledgment frame. For example, as shown in FIG. 5, the AID
subfields 502 include a first AID (AID1) subfield 502-1, a second
AID (AID2) subfield 502-2, and a third AID (AID3) subfield 502-3
with corresponding first bitmap (BM1) subfield 504-1, second bitmap
(BM2) subfield 504-2, and third bitmap (BM3) subfield 504-3. In one
embodiment, the broadcast block acknowledgment field 500 is
generated by the host processor 15 (e.g., by a management
processing unit of the host processor 15). In another embodiment,
at least one of the AID subfields 502, and/or information included
therein, are generated at least in part by the MAC processing unit
18. The bitmap subfield 504 includes a bitmap having as many bits
as MPDUs transmitted by the corresponding client station 25. For
example, in an embodiment, a client station 25 transmits an A-MPDU
having six MPDUs to the AP 14 and, in response, the AP 14 transmits
an acknowledgment frame having a bitmap subfield 504 with a size of
six bits. In this embodiment, each bit of the bitmap indicates
whether the corresponding MPDU was successfully received.
[0057] FIG. 6 is diagram illustrating a frame exchange 600 between
an AP (e.g., the AP 14) and multiple client stations (e.g.,
multiple client stations 25), according to an embodiment. During a
time t1, the AP 14 transmits an OFDMA data unit 602 directed to a
plurality of client stations. In an embodiment, the AP 14 uses a
medium access procedure or backoff procedure to determine when to
transmit the downlink OFDMA data unit 602. In an embodiment, the
backoff procedure is an enhanced distributed channel access (EDCA)
backoff procedure (e.g., shared with single user EDCA traffic). In
an embodiment, the backoff procedure is a backoff procedure
specific to OFDMA. The OFDMA data unit 602 occupies an 80 MHz
channel, in the illustrated embodiment. In an embodiment, the data
unit 602 is the same as or similar to the data unit 300 of FIG. 3.
In an embodiment, prior to transmission of the OFDMA data unit 602,
the AP 14 conducts a suitable channel assessment procedure, such as
a carrier sense multiple access with collision avoidance procedure
(CSMA/CA) procedure, and based on the channel assessment procedure
determines a bandwidth available for transmission by the AP 14. In
an embodiment, the OFDM channel includes the primary channel of the
WLAN 10 and one or more secondary channels of the WLAN 10. For
example, the AP 14 determines that the primary 20 MHz channel and
three secondary 20 MHz channels of the WLAN 10 are available for 80
MHz transmission by the AP 14, in the illustrated embodiment.
[0058] In an embodiment, the OFDMA data unit 602 includes a
plurality of OFDM data units 604 directed to respective client
stations 25, each OFDM data unit 604 transmitted in a respective
sub-channel of the WLAN 10 to a particular client station 25. In
particular, a first OFDM data unit 604-1 is directed to a first
client station STA1 (e.g., the client station 25-1), a second OFDM
data unit 604-2 is directed to a second client station STA2 (e.g.,
the client station 25-2), and a third OFDM data unit 604-3 is
directed to a third client station STA3 (e.g., the client station
25-3), in the illustrated embodiment. In an embodiment, the first
OFDM data unit 604-1 occupies the highest 20 MHz sub-channel of the
80 MHz channel, the second OFDM data unit 604-2 occupies the second
highest 20 MHz sub-channel of the 80 MHz channel, and the third
OFDM data unit 604-3 is transmitted in a 40 MHZ sub-channel that
includes the lowest two 20 MHZ sub-channels of the 80 MHz
channel.
[0059] In an embodiment, the preamble of the OFDMA data unit 600 is
transmitted in each of the 20 MHz sub-channels occupied by the
OFDMA data unit 602. In an embodiment, the preamble of the OFDMA
data unit 600 includes a channel allocation field (e.g., in a
signal field of the preamble such as the HEW-SIGA field of the
preamble) that indicates to the client stations 25 to which the
OFDMA data unit 600 is directed that the client station 25 are
intended recipients of different portions of the OFDMA data unit
600. An example of a channel allocation field is described in U.S.
patent application Ser. No. 14/538,573, entitled "Medium Access
Control for Multi-Channel OFDM in a Wireless Local Area Network,"
filed on Nov. 11, 2014, the disclosure of which is hereby
incorporated herein by reference in its entirety.
[0060] Each of the client stations 25 receives the channel
allocation field in the primary channel of the WLAN 10 (e.g., in
the lowest 20 MHz channel) and determines, based on the channel
allocation field, which channel of the WLAN 10 includes data
directed to the client station 25, respectively, in an embodiment.
The client stations 25 tune to the appropriate sub-channels
indicated in the channel allocation field and receive data directed
to the client stations 25 via the respective sub-channels allocated
to the client station 25. During a time t2, in an embodiment,
client stations 25 that successfully receive data in the respective
sub-channels allocated to the client stations 25 transmit
respective acknowledgement (ACK or BlkAck) frames 606 to the AP 14.
In an embodiment, each client station 25 transmits its
acknowledgement (ACK or BlkAck) frame 606 in the respective
sub-channel allocated to the client station 25. In an embodiment,
the AP 14 allocates a sub-channel for the acknowledgment to be
transmitted from each client station that is different from a
sub-channel allocated for downlink OFDMA transmissions to the
corresponding client station. In an embodiment, the AP 14
synchronizes transmission of the ACK frames 606 from the client
stations 25 by ensuring that the OFDM data units 604-1, 604-2,
604-3 are of equal length. For example, the AP adds padding bits
(e.g., bits having predetermined values such as zero bits or one
bits) to data bits in one or more of the data units 604 to equalize
lengths of the data units 604, in an embodiment. For example, in an
embodiment in which the OFDM data units 604-1, 604-2, 604-3 are
A-MPDUs, and the AP 14 utilizes A-MPDU padding in one or more of
the data units 604-1, 604-2, 604-3 to ensure that the data units
604-1, 604-2, 604-3 are of the same length. As another example, in
an embodiment in which the OFDM data units 604-1, 604-2, 604-3 are
MPDUs, and the AP 14 utilizes MPDU padding in one or more of the
data units 604-1, 604-2, 604-3 to ensure that the data units 604-1,
604-2, 604-3 are of the same length.
[0061] In another embodiment, the ACK frames 606 are not
simultaneously transmitted by the client stations 25. For example,
transmission of the ACK frames 506 is staggered among the client
stations 25, in an embodiment. For example, the AP provides to the
client stations 25 indications of different specific times at which
to transmit their respective ACK frames 606, or a specific order in
which to transmit their respective ACK frames 606, and the client
stations 25 transmit the ACK frames 606 at the specific times or in
the specific order indicated by the AP, in an embodiment.
[0062] In an embodiment, the ACK frames 606 are block
acknowledgement (BlkAck) frames that indicate successful or
unsuccessful reception of a plurality of data units, such as of a
plurality of data units aggregated in the corresponding A-MPDU 602.
Generally speaking, as used herein, the terms "acknowledgement
frame" and "ACK frame" are used interchangeably and encompass both
an acknowledgement frame that acknowledges successful or
unsuccessful receipt of a single data unit, and a block
acknowledgement frame that acknowledges successful or unsuccessful
receipt of multiple data units (e.g., multiple data units
transmitted as parts of an aggregated data unit).
[0063] In an embodiment, the bandwidth of acknowledgment 606 is not
wider than the bandwidth of downlink OFDMA transmission 602, and in
each 20 MHz channel occupied by the downlink OFDMA transmission
602, there is at least one sub-channel for transmission of the
acknowledgment.
[0064] In some embodiments, the AP 14 transmits a control frame,
such as a scheduling frame, to the client stations 25 prior to
transmission of an OFDMA data unit to the client stations 25. In an
embodiment, the control frame that the AP 14 transmits to the
client stations 25 prior to transmission of an OFDMA data unit to
the client stations 25 is a legacy (e.g., an IEEE 802.11 a or an
IEEE 802.11 g) duplicate control frame that is replicated in each
smallest bandwidth band (e.g., each 20 MHz band) of the WLAN 10. In
an embodiment, the AP 14 transmits the control frame at the
beginning of a transmission opportunity (TXOP) to inform the client
stations 25 whether the client stations 25 are to receive data from
the AP 14 and/or are to transmit data to the AP 14 during the TXOP.
The control frame includes downlink and/or uplink channel
allocation information that indicates to the client stations 25
that are to receive and/or transmit data which sub-channels to use
for reception and/or transmission of data, in an embodiment. In an
embodiment, the downlink channel allocation information is carried
in a downlink PHY signal field (e.g., a SIG field). In one such
embodiment, a separate control frame is omitted. In an embodiment,
the client stations 25 are configured to determine their respective
downlink sub-channels based on downlink channel allocation
information included in the control frame and to subsequently
simultaneously receive, via the downlink sub-channels, data from
the AP 14 with the other client stations 25 as part of a downlink
OFDMA transmission from the AP 14. Similarly, the client stations
25 are configured to determine their respective uplink channels
based on uplink channel allocation information included in the
control frame and to subsequently simultaneously transmit data to
the AP 14 with the other client stations 25 as part of an uplink
OFDMA transmission to the AP 14, in an embodiment.
[0065] In at least some embodiments in which the AP 14 transmits a
control frame to the client stations 25 to signal downlink channel
allocation to the client stations 25 for a downlink OFDMA
transmission to the client stations 25, such channel allocation
information need not be included in a preamble of each of the OFDM
data unit transmitted as part of the OFDMA transmission. In one
such embodiment, the preamble of each data unit in an OFDMA
transmission is generally the same as a preamble used for regular
OFDM transmission to single client station 25. For example, with
reference to FIGS. 3 and 4, the signal field 310 of each of the
data units 302 is the same as a HEW-SIGA field of a data unit
transmitted as a regular transmission to a single client station
25. In another embodiment, the preamble of each OFDM data unit
included in the OFDMA transition is substantially the same as a
preamble used for regular OFDM transmission to single client
station 25, but includes an indication that the OFDM data unit is
part of an OFDMA transmission to multiple client stations 25. For
example, with reference to FIGS. 3 and 4, one or more bits of the
signal field 310 is/are set to indicate that the OFDM data units
302 are part of an OFDMA transmission, in an embodiment.
[0066] FIG. 7 is a diagram illustrating various acknowledgment
types during single user frame exchanges 700, 710, and 720 for a
transmission opportunity (TXOP) holder using enhanced distributed
channel access (EDCA), according to an embodiment. The frame
exchanges 700, 710, and 720 are "single user" in that each includes
a transmission of an A-MPDU from a single access point (e.g., the
AP 14) to a single client station (e.g., client station 25-1). In
an embodiment, an AP 14 obtains a TXOP and transmits one or more
A-MPDUs to a client station 25. In the embodiment shown in FIG. 7,
each frame exchange 700, 710, and 720 is performed within a TXOP of
the AP 14. In an embodiment, the TXOP holder (e.g., the AP 14)
indicates the acknowledgment type (e.g., Normal Acknowledgment,
Implicit Block Acknowledgment, No Acknowledgment, No Explicit
Acknowledgment, Block Acknowledgment) through an Acknowledgment
Policy in a header of at least some of its transmitted frames, for
example, in a Quality of Service (QoS) control field.
[0067] The frame exchange 700 illustrates a Block Acknowledgment
where the client station 25 does not provide an immediate
acknowledgment to frames received from the AP 14. In the embodiment
shown in FIG. 7, during the frame exchange 700, the AP 14 transmits
a first A-MPDU 702 and a second A-MPDU 704 in a downlink (DL)
direction to the client station 25 (STA1). In an embodiment, the
client station 25 waits for receipt of a block acknowledgment
request (BAR) 706 from the AP 14 before sending a block
acknowledgment 708 to the AP 14. The frame exchange 710 illustrates
an Implicit Block Acknowledgment where the client station 25
transmits a block acknowledgment 714 in response to and upon
receipt of an A-MPDU 712. The frame exchange 720 illustrates a
Normal Acknowledgment where the client station 25 transmits an
acknowledgment 724 in response to and upon receipt of a very high
throughput (VHT) single MPDU or MPDU 722.
[0068] In some embodiments and/or scenarios, the AP 14 selects one
or more quality of service indicators (e.g., traffic classes or
access categories) for a frame exchange. In some embodiments, the
AP 14 selects the quality of service indicator based on a medium
access procedure used to trigger the frame exchange. In an
embodiment, the block acknowledgment allows the AP 14 to select
frames having different traffic classes (TC) and/or frames intended
for different receiver addresses (RA) for inclusion within a same
A-MPDU. In an embodiment, the AP 14 selects data frames with a same
access category (AC) to be encapsulated within an A-MPDU. In an
embodiment, responding frames (e.g., the acknowledgments 708, 714,
and 724) have a same bandwidth as a preceding frame which elicits
the responding frame (e.g., the block acknowledgment request 706,
the A-MPDU 712, or the A-MPDU 722), with the exception of clear to
send (CTS) frames which may have a smaller bandwidth than a
preceding request to send (RTS) frame. When transmitting a frame,
the TXOP holder uses a bandwidth that is not wider than i) a
preceding frame or ii) the elicited acknowledgment when a duplicate
frame was not previously transmitted. Otherwise, the TXOP holder
uses a bandwidth that is not wider than a preceding duplicate CTS
frame.
[0069] FIG. 8 is a diagram illustrating a block acknowledgment
during a frame exchange 800 for a TXOP holder using EDCA, according
to an embodiment. In an embodiment, the frame exchange 800 is a
"multi-user" in that an access point (e.g., the AP 14) performs a
multi-user multiple input, multiple output (MU-MIMO) transmission
804 having separate OFDM data units 806-1 and 806-2 intended for
two client stations STA1 and STA2 (e.g., client stations 25-1 and
25-2). In an embodiment, the AP 14 obtains a TXOP and
simultaneously transmits a first A-MPDU 806-1 to the client station
25-1 and transmits a second A-MPDU 806-2 to the client station 25-2
using different sub-channels (i.e., space time streams) of a
MU-MIMO communication channel. In the embodiment shown in FIG. 8,
the MU-MIMO transmission 804 includes data frames from a same
access category (AC). In the simultaneously transmitted A-MPDUs
806-1 and 806-2, data frames from a same AC are encapsulated in
each A-MPDU by the AP 14, in an embodiment. In some embodiments,
when TXOP sharing is allowed, data frames from different ACs are
encapsulated in different A-MPDUs within the TXOP. In one such
embodiment, the MPDUs from a primary AC have higher priority to be
transmitted. When TXOP sharing is not allowed, data frames from the
primary AC can be encapsulated in different A-MPDUs.
[0070] In the embodiment shown in FIG. 8, the A-MPDU 806-1
corresponds to an indication of an Implicit Block Acknowledgment
and the A-MPDU 806-2 corresponds to an indication of a Block
Acknowledgment. Based on the indication of the Implicit Block
Acknowledgment, the client station 25-1 transmits a block
acknowledgment 810 to the AP 14 in response to and upon receipt of
the A-MPDU 806-1. The client station 25-2, based on the indication
of the Block Acknowledgment, waits for receipt of a block
acknowledgment request (BAR) 820 from the AP 14 before sending a
block acknowledgment 830 to the AP 14. The block acknowledgment
830, in some embodiments, is transmitted using a same bandwidth as
the original MU-MIMO transmission 804. For example, in an
embodiment, the MU-MIMO transmission 804 occupies a bandwidth of 40
MHz (e.g., 2.times.20 MHz sub-channels) and the block
acknowledgment 830 is duplicated across a same bandwidth.
[0071] FIG. 9 is a diagram illustrating a frame exchange 900
between an AP (e.g., AP 14) and a plurality of client stations
(e.g., client stations 25) that includes an uplink transmission of
data from the plurality of client stations to the AP, according to
an embodiment. In some embodiments, the uplink transmission
includes a MU-MIMO data transmission. In some embodiments, the
uplink transmission includes an OFDMA data transmission.
[0072] During a time t1, the AP 14 transmits an uplink scheduling
frame 904 to a plurality of client stations 25. In an embodiment,
the time t1 begins at the beginning of a TXOP 902 obtained by
(e.g., based on a suitable channel assessment procedure, such as
CSMA/CA), or scheduled for (e.g., through a target wake time (TWT)
service period), the AP 14. In an embodiment, the uplink scheduling
frame 904 provides, to the plurality of client stations 25, MU-MIMO
uplink scheduling information to be used for transmission of an
uplink OFDM data unit during the TXOP 902 via an allocated space
time stream. In an embodiment, the uplink scheduling frame 904
includes MU-MIMO scheduling information, for example, one or more
identifiers of space time streams for the client stations. In an
embodiment, the scheduling frame 904 further indicates, to each of
the client stations STA1 and STA2 a length or duration to be used
for transmission of an uplink data unit during the TXOP 902. In
another embodiment, the uplink scheduling frame 904 provides, to
the plurality of client stations 25, OFDMA uplink scheduling
information to be used for transmission of an uplink OFDM data unit
during the TXOP 902 via a sub-channel of the OFDM communication
channel. In an embodiment, the uplink scheduling frame 904 includes
OFDMA scheduling information, for example, one or more identifiers
of transmission bandwidth for the client stations. In an
embodiment, the scheduling frame 904 further indicates, to each of
the client stations STA1 and STA2 a length or duration to be used
for transmission of an uplink data unit during the TXOP 902.
[0073] In an embodiment, the scheduling frame 904 is a
synchronization (SYNC) frame, control frame, trigger frame, or
other suitable frame. In an embodiment, the scheduling frame 904 is
a non-data packet (NDP) frame that omits a payload. In one
embodiment in which the scheduling frame 904 in an NDP frame, MAC
layer information, e.g., receiver address, transmitter address,
etc., is included in a signal field of a PHY preamble of the
scheduling frame 904. In an embodiment and/or scenario, the uplink
scheduling frame 904 is duplicated in each smallest bandwidth
portion (e.g., in each 20 MHz) of the entire bandwidth of the TXOP
902. In another embodiment and/or scenario, the scheduling frame
904 occupies the entire bandwidth of the TXOP 902, for example when
each of the client stations 25 to which the scheduling frame 904 is
transmitted is capable of operating in the entire bandwidth of the
TXOP 902. In another embodiment and/or scenario, the uplink
scheduling frame 904 is duplicated in every bandwidth portion of
the entire bandwidth of the TXOP 902 so as to allow each client
station 25 to which the scheduling frame 904 is transmitted to
receive and decode the scheduling frame 904, according to
capabilities of the client stations 25 to which the scheduling
frame 904 is directed. For example, if the entire bandwidth of the
TXOP is 160 MHz, but at least one of the client stations 25 to
which the scheduling frame 904 is directed is capable to operate
with a maximum bandwidth of 80 MHz, then the scheduling frame 904
occupies 80 MHz and is duplicated in each 80 MHz portion of the
entire bandwidth of the TXOP (i.e., in the lower 80 MHz portion and
the upper 80 MHz portion), in an embodiment.
[0074] The scheduling frame 904 indicates different sub-channels
allocated for uplink transmission by the client stations, in
various embodiments. While only two client stations STA1 and STA2
are shown in FIG. 9, the scheduling frame 904 indicates
sub-channels allocated for three, four, or another suitable number
of client stations in other embodiments and/or scenarios. In an
embodiment, the scheduling frame 904 indicates a first space time
stream allocated to STA1 and a second space time stream allocated
to STA2 for a MU-MIMO transmission. In another embodiment, the
scheduling frame 904 indicates a first 20 MHz bandwidth of a 40 MHz
OFDM communication channel allocated to STA1 and a second 20 MHz
bandwidth of the 40 MHz OFDM communication channel allocated to
STA2 for an OFDMA transmission. In other embodiments, the AP 14
allocates other suitable combinations of sub-channels to the client
stations. In an embodiment, the AP 14 allocates an equal number of
sub-channels to each client station. In another embodiment, the AP
14 allocates an unequal number of sub-channels to the client
stations. In one such embodiment, the AP 14 allocates a 20 MHz
sub-channel to a first client station and a 60 MHz sub-channel
(e.g., three separate 20 MHz sub-channels) to a second client
station.
[0075] During a time t2, the plurality of client stations 25
transmit respective OFDM data units 908 to the AP 14. Time t2 at
each client station 25 begins upon expiration of a predetermined
time interval, such as for example a time interval corresponding to
a short inter-frame space (SIFS), after completion of reception, of
the scheduling frame 904 at the client station 25, in an
embodiment. In another embodiment, a predetermined time period that
is greater than SIFS is defined, and time t2 at each client station
25 begins upon expiration of a predetermined time interval
corresponding to the predetermined time interval greater than SIFS.
For example, a predetermined time period that is greater than SIFS
and less than point coordination function (PCF) interframe space
(PIFS) is defined. The greater predetermined time interval may
provide sufficient time for the client stations 25 to decode the
scheduling frame 904 and to prepare for uplink transmission based
on the uplink scheduling information provided by the scheduling
frame 904, in at least some embodiments. Additionally or
alternatively, the scheduling frame 904 includes one or more
padding bits at the end of the scheduling frame 904 to provide
sufficient time for the client stations 25 to prepare for uplink
transmission based on the uplink scheduling information provided by
the scheduling frame 904, in some embodiments. For example, a MAC
header included in the scheduling frame 904 indicates a length of a
valid payload, wherein the one or more padding bits follow the
valid payload, in an embodiment. Further, a signal field of a PHY
preamble of the scheduling frame 904 includes an indication of the
entire length of the scheduling frame 904, which includes the one
or more padding bits at the end of the scheduling frame 904, in an
embodiment.
[0076] In an embodiment, each client station 25 transmits its OFDM
data unit 908 during the time t2 in a respective sub-channel,
allocated to the client station 25, as indicated in the scheduling
frame 904. In an embodiment, the length or duration of each of the
OFDM data units 908 corresponds to the length or duration indicated
in the scheduling frame 904.
[0077] During a time t3, the AP 14 transmits respective ACK frames
910 and 912 to the client stations 25 (STA1 and STA2) acknowledging
receipt of the OFDM data units 908 from the client stations 25.
Time t3 begins upon expiration of a predetermined time interval,
such as for example a time interval corresponding to a short
inter-frame space (SIFS), after completion of reception of the OFDM
data units 908 at the AP 14, in an embodiment. In an embodiment,
the AP 14 transmits the ACK frames 910 and 912 to the client
stations 25, as parts of a MU-MIMO transmission to the client
stations 25, in the respective sub-channels allocated to the client
stations 25 indicated in the scheduling frame 904 (e.g., in a same
bandwidth as the corresponding scheduling frame). In another
embodiment, the AP 14 transmits the ACK frames 910 and 912 to the
client stations 25 as parts of an OFDMA transmission to the client
stations 25 in the respective sub-channels allocated to the client
stations 25 indicated in the scheduling frame 904. In some
embodiments, an acknowledgment policy indicates whether an
acknowledgment to an uplink OFDM data unit is required or optional
and whether the acknowledgment should be sent in response to the
receipt of the OFDM data unit or delayed. In an embodiment, the AP
14 determines an order in which acknowledgments are to be
transmitted in response to receipt of the uplink OFDM data units
from the client stations. In some embodiments, the ACK frames 910
and 912 are duplicated in each smallest bandwidth portion (e.g., in
each 20 MHz) of the entire bandwidth of the TXOP 902. For example,
in an embodiment, the AP transmits a legacy OFDM data unit as the
ACK frames 910 and 912.
[0078] In an embodiment, the AP 14 is configured to transmit a
broadcast acknowledgement frame 960 instead of the ACK frames 910
and 912. FIG. 9 illustrates a TXOP 952 of the AP 14, during which
the AP transmits a scheduling frame 954 and receives uplink OFDM
data units 958 from the client stations 25. The TXOP 952 is
generally similar to the TXOP 902, except that the AP 14 transmits
a broadcast acknowledgement frame 960 that includes respective
acknowledgements for the client stations 25 and omits the ACK
frames 910 and 912. In an embodiment, the broadcast acknowledgment
frame 960 includes the broadcast block acknowledgment field 500, as
described above with respect to FIG. 5. In some embodiments, the AP
14 performs more than one frame exchange during a TXOP. In the
embodiment shown in FIG. 9, the TXOP 952 includes a first frame
exchange (i.e., scheduling frame 954, uplink OFDM data units 958,
and broadcast acknowledgment frame 960) and a second frame
exchange. The second frame exchange includes a scheduling frame
964, an uplink OFDM data unit 968, and a block acknowledgment frame
970.
[0079] In some embodiments, the client station 25 is configured to
respond to a scheduling frame without determining whether the
sub-channel indicated in the scheduling frame is busy during a time
period between the receipt of the scheduling frame and the
transmission of the uplink OFDM data unit. In other embodiments,
the client station 25 is configured to determine whether the
allocated sub-channel is busy. In an embodiment, the client station
is allocated one sub-channel and in response to a determination
that the one sub-channel is busy, the client station omits
transmitting the uplink OFDM data unit. In an embodiment, when at
least one 20 MHz channel that covers the client station's
sub-channel is busy, the sub-channel of the client station is
determined to be busy. In other embodiments, the client station is
allocated a primary 20 MHz channel and at least one additional
sub-channel is allocated to the STA. In another embodiment, when at
least a portion of the client station's sub-channel is determined
to be busy (e.g., a 20 MHz bandwidth portion is busy within a 40
MHz sub-channel), the client station omits transmitting uplink OFDM
data units on only those sub-channels which are determined to be
busy. In some embodiments, the client station 25 determines whether
a primary channel or sub-channel of a communication channel is busy
using a network access allocation (NAV) timer. In some embodiments,
the client station 25 determines whether a non-primary channel is
busy based on an idle period corresponding to a point coordination
function (PCF) interframe space (PIFS) between the receipt of the
scheduling frame and the transmission of the uplink OFDM data unit.
Other interframe spaces can also be used for an idle/busy
determination. In an embodiment, a client station makes an
idle/busy determination in an entire bandwidth of a trigger frame
(e.g., the synchronization frame 904). If the determination result
is busy, the client station will not transmit the uplink OFDMA
frames.
[0080] In an embodiment, the uplink OFDM data unit 908 acts as an
acknowledgment of the scheduling frame 904. In one such embodiment,
the AP 14 determines whether the scheduling frame 904 was
transmitted correctly based upon whether an uplink OFDM data unit
is received after transmission of the scheduling frame 904. In an
embodiment, for example, when the AP 14 receives the uplink OFDM
data unit from at least one client station that responds to a first
scheduling frame of a TXOP, the AP continues to use the TXOP for
frame exchanges. In another embodiment, when the AP does not
receive an uplink OFDM data unit in response to the scheduling
frame, the AP does not send downlink OFDM data units for the
remainder of the TXOP to those client stations that did not
respond.
[0081] In an embodiment, the total bandwidth of the uplink OFDMA
transmission is determined based on the bandwidth of the trigger
frame. In one such embodiment, the sub-channel of a client station
does not include a 20 MHz channel that is not covered by the
bandwidth of the trigger frame. In an embodiment, in each 20 MHz
channel that is covered by the transmission of the trigger frame,
there is at least one sub-channel allocated to a client
station.
[0082] FIG. 10 is a frame exchange between an AP 14 and a plurality
of client stations 25 that includes uplink OFDMA transmission of
data from the plurality client stations 25 to the AP 14, according
to another embodiment. In some embodiments, the AP uses the backoff
procedure to determine when to transmit the uplink scheduling frame
1002. In an embodiment, the backoff procedure use the EDCA backoff
procedure (shared with single user EDCA traffic). In an embodiment,
the backoff procedure is a backoff procedure specific to OFDMA.
During a time t1, the AP 14 transmits an uplink scheduling frame
1002 to a plurality of client stations 25. In an embodiment, the
uplink scheduling frame 1002 is generally similar to the uplink
scheduling frame 904. In an embodiment, the time t1 begins at the
beginning of a TXOP obtained by (e.g., based on a suitable channel
assessment procedure, such as CSMA/CA), or scheduled for (e.g.
through a target wake time (TWT) service period), the AP 14. In an
embodiment, the uplink scheduling frame 1002 provides, to the
plurality of client stations 25, OFDMA uplink scheduling
information to be used for transmission of an uplink OFDMA data
unit during the TXOP. In an embodiment, the scheduling frame 1002
further indicates, to each of the client stations STA1, STA2, STA3,
a length or duration to be used for transmission of an uplink data
unit during the TXOP.
[0083] In an embodiment and/or scenario, the uplink scheduling
frame 1002 is duplicated in each smallest bandwidth portion (e.g.,
in each 20 MHz) of the entire bandwidth of the TXOP. In another
embodiment and/or scenario, the scheduling frame 1002 occupies the
entire bandwidth of the TXOP, for example when each of the client
stations 25 to which the scheduling frame 1002 is transmitted is
capable of operating in the entire bandwidth of the TXOP. In
another embodiment and/or scenario, the uplink scheduling frame
1002 is duplicated in every bandwidth portion of the entire
bandwidth of the TXOP so as to allow each client station 25 to
which the scheduling frame 1002 is transmitted to receive and
decode the scheduling frame 1002, according to capabilities of the
client stations 25 to which the scheduling frame 1002 is
directed.
[0084] The scheduling frame 1002 indicates respective sub-channels
allocated for uplink OFDMA transmission by three client stations
STA1, STA2 and STA3, in the illustrated embodiment. For example,
the scheduling frame 1002 indicates channel allocation within an 80
MHz channel, and indicates that (i) the highest 20 MHz sub-channel
of the 80 MHz channel is allocated to STA2, (ii) the second highest
20 MHz sub-channel of the 80 MHz channel is allocated to STA1 and
(iii) a 40 MHz sub-channel that includes the second lowest 20 MHz
sub-channel and the lowest 20 MHz sub-channel is allocated to STA0,
in an embodiment.
[0085] During a time t2, the plurality of client stations 25
transmit respective OFDM data units 1006 that collectively form an
OFDMA data unit 1004 to the AP 14. The OFDM data units 1006 are
generally similar to uplink OFDM data unit 908, except that the
client station STA1 does not respond to the scheduling frame 1002,
for example, because the client station STA1 does not receive the
trigger frame correctly or detects a busy medium in its allocated
sub-channel. In an embodiment, each client station 25 transmits its
OFDM data unit 1006 during the time t2 in a respective sub-channel,
allocated to the client station 25, as indicated in the scheduling
frame 1002. In an embodiment, the length or duration of each of the
OFDM data units 1006 corresponds to the length or duration
indicated in the scheduling frame 1002.
[0086] During a time t3, the AP 14 transmits respective ACK frames
1008 to the client stations 25 (STA0, STA2) acknowledging receipt
of the OFDM data units 1006 from the client stations 25. The ACK
frames 1008 are generally similar to the ACK frames 910 and 912, in
an embodiment. In another embodiment, the AP 14 transmits a
broadcast acknowledgement frame that includes respective
acknowledgements for the client stations 25 (STA0, STA2). In an
embodiment, the AP 14 transmits the ACK frames 1008 to the client
stations 25, as parts of an OFDMA transmission to the client
stations 25, in the respective sub-channels allocated to the client
stations 25 indicated in the scheduling frame 1002. In an
embodiment, a negative acknowledgment (NAK) is transmitted to STA1
because the AP did not receive uplink frames from STA1 in t2. In an
embodiment, the NAK is a Quality of Service (QoS) Null frame or an
MPDU Delimiter. In an embodiment, without bandwidth protection
provided by a request to send/clear to send (RTS/CTS) exchange, the
scheduling frame determines a bandwidth of a frame exchange and
subsequent frame exchanges within a TXOP. In the illustrated
embodiment, the AP 14 transmits the ACK frames 1008 to each of the
plurality of client stations, including the NAK to the client
station STA1, in order to maintain the entire bandwidth (e.g., 80
MHz, including the 20 MHz allocated to STA1) of the communication
channel. In the illustrated embodiment, the client station STA1
transmits an uplink OFDM data unit without determining whether the
sub-channel indicated in the scheduling frame 1012 is busy.
[0087] In the illustrated embodiment of FIG. 10, the AP 14
transmits an additional scheduling frame 1012 during a same TXOP as
the 1002. The scheduling frame 1012 indicates respective
sub-channels allocated for uplink OFDMA transmission by the three
client stations STA0, STA1 and STA2, in an embodiment. For example,
the AP 14 makes additional attempts to use the second highest 20
MHz sub-channel to determine whether the sub-channel is no longer
busy.
[0088] FIG. 11 is a frame exchange 1100 between an AP and a
plurality of client stations that includes uplink OFDMA
transmission of data from the plurality client stations to the AP,
according to another embodiment. The frame exchange 1100 is
generally similar to the frame exchange 1000, except that a
scheduling frame 1112 is transmitted within a same TXOP after a
scheduling frame 1102 allocates a total bandwidth that is less than
the scheduling frame 1102. In the embodiment shown, the highest and
the second highest 20 MHz sub-channels of the 80 MHz channel are
not allocated by the scheduling frame 1112.
[0089] FIG. 12 is a frame exchange 1200 between an AP and a
plurality of client stations that includes uplink OFDMA
transmission of data from the plurality client stations to the AP,
according to another embodiment. The frame exchange 1200 is
generally similar to the frame exchange 1000, except that the
sub-channel allocated to the client station STA1 is not used for
the client station STA1 in the following OFDMA transmission when
the AP 14 does not receive frames in the first uplink frame
exchange from the client station STA1 in its cub-channel. In the
illustrated embodiment, the second highest 20 MHz sub-channel
allocated to the client station STA1 is not used during the TXOP.
In another embodiment, the unused sub-channel is allocated to
another client station for a remainder of the TXOP.
[0090] FIG. 13 is a frame exchange 1300 between an AP and a
plurality of client stations that includes uplink OFDMA
transmission of data from the plurality client stations the AP,
according to an embodiment. The frame exchange 1300 is generally
similar to the frame exchange 1200, except that when the AP 14 does
not receive an uplink OFDM data unit on a sub-channel 1305
allocated to a client station, the AP 14 does not use the allocated
sub-channel for a remainder of the TXOP.
[0091] FIG. 14 is a frame exchange 1400 between an AP and a
plurality of client stations that includes uplink OFDMA
transmission of data from the plurality client stations the AP,
according to an embodiment. The frame exchange 1400 is generally
similar to the frame exchange 1000 of FIG. 10, except that in the
frame exchange 1400, a scheduling frame 1402 indicates
noncontiguous channel allocation to a plurality of client stations
25. In an embodiment, prior to transmitting the scheduling frame
1402, the AP 14 detects that a particular sub-channel 1401 is
currently not available (e.g., busy). For example, the AP 14
detects that the second highest 20 MHz sub-channel of the 80 MHz
channel is busy, while the remaining 20 MHz sub-channels of the 80
MHz are available. Then, during a time t1, the AP 14 transmits the
scheduling frame 1402 on each of the available sub-channels of the
80 MHz channel. The scheduling frame 1402 is similar to the
scheduling frame 902 except that the scheduling frame 1402
indicates channels allocated to STA0 and STA2, but not STA1, in the
illustrated embodiment. In particular, the scheduling frame 1402
indicates that (i) the highest 20 MHz sub-channel of the 80 MHz
channel is allocated to STA2, and (ii) a 40 MHz sub-channel that
includes the second lowest 20 MHz sub-channel and the lowest 20 MHz
sub-channel is allocated to STA0, in the illustrated
embodiment.
[0092] In an embodiment, during a time t2, stations STA0 and STA2
transmit respective OFDM data units 1404 that collectively form an
OFDMA data unit to the AP 14. In an embodiment, the client stations
STA0 and STA2 transmit their respective OFDM data units 1404 in a
respective non-contiguous sub-channels allocated to the client
stations STA0 and STA2, as indicated in the scheduling frame 1402.
During a time t3, the AP 14 transmits respective ACK frames 1408 to
the client stations SAT0 and STA2 acknowledging successful receipt
of the OFDM data units 1404 from the client stations STA0 and STA2,
in an embodiment. The AP transmits the ACK frame 1408 to the client
stations STA0 and STA2, as parts of an OFDMA transmission to the
client stations STA0 and STA2, in the respective non-contiguous
sub-channels allocated to the client stations STA0 and STA2, in an
embodiment. In another embodiment, the AP 14 transmits a broadcast
acknowledgement frame that includes respective acknowledgements for
the client stations 25 (STA0 and STA2).
[0093] While an 80 MHz communication channel is allocated to the
client stations in the illustrated embodiment, the AP 14 selects
other sub-channel allocations (e.g., 60 MHz, 100 MHz, 120 MHz, 140
MHz, etc.) in other embodiments and/or scenarios. In an embodiment,
the AP 14 selects contiguous blocks of 40 MHz, 80 MHz, or 160 MHz
for an uplink MU-MIMO transmission. In some embodiments, a physical
layer clear channel assessment (PHY-CCA) provides an idle/busy
indication for each 20 MHz sub-channel of a communication channel.
In an embodiment, the PHY-CCA is redefined to provide at least some
sub-channel allocations.
[0094] FIG. 15 is a frame exchange 1500 between an AP and a
plurality of client stations that includes uplink OFDMA
transmission of data from the plurality client stations the AP,
according to an embodiment. The frame exchange 1500 is generally
similar to the frame exchange 1000 of FIG. 10, except that in the
frame exchange 1500, the total bandwidth of the OFDMA transmission
is not one of 20/40/80/160/80+80 MHz. In an embodiment, prior to
transmitting the scheduling frame 1502, the AP 14 detects that a
particular sub-channel 1501 is currently not available (e.g.,
busy). For example, the AP 14 detects that the highest 20 MHz
sub-channel of the 80 MHz channel is busy, while the remaining 20
MHz sub-channels of the 80 MHz are available. Then, during a time
t1, the AP 14 transmits the scheduling frame 1502 on each of the
available sub-channels of the 80 MHz channel. The scheduling frame
1502 is similar to the scheduling frame 902 except that the
scheduling frame 1502 indicates channels allocated to STA0 and
STA1, but not STA2, in the illustrated embodiment. In particular,
the scheduling frame 1502 indicates that (i) the second highest 20
MHz sub-channel of the 80 MHz channel is allocated to STA1, and
(ii) a 40 MHz sub-channel that includes the second lowest 20 MHz
sub-channel and the lowest 20 MHz sub-channel is allocated to STA0,
in the illustrated embodiment.
[0095] FIG. 16 is a frame exchange 1600 between an AP and a
plurality of client stations that includes uplink OFDMA
transmission of data from the plurality client stations the AP,
according to another embodiment. In the frame exchange 1600, the AP
14 determines that a primary sub-channel 1601 of an OFDM
communication channel is busy. In an embodiment, the frame exchange
1600 occurs during a scheduled service period. In this embodiment,
the AP 14 determines an availability of the sub-channel 1601 of the
OFDM communication channel based on an idle state during a point
coordination function interframe space (PIFS). In an embodiment,
the AP 14 performs the frame exchange 1600 using only the
sub-channels determined to be not busy.
[0096] FIG. 17 is a frame exchange 1700 between an AP 14 and a
plurality of client stations (STA1 and STA2) that includes downlink
OFDMA transmission 1704 of data from the AP to the plurality client
stations, according to an embodiment. In an embodiment, the AP 14
obtains a TXOP 1702 and simultaneously transmits a first downlink
A-MPDU 1703-1 to the client station STA1 and transmits a second
downlink A-MPDU 1703-2 to the client station STA2 using different
sub-channels (i.e., tone blocks) of an OFDMA communication channel.
In some embodiments, an acknowledgment policy indicates whether an
acknowledgment to an uplink OFDM data unit is required or optional
and whether the acknowledgment should be sent in response to the
receipt of the OFDM data unit or delayed. In an embodiment, the AP
14 determines an order in which acknowledgments are to be
transmitted in response to receipt of the uplink OFDM data units
from the client stations. In the embodiment shown in FIG. 17, the
first downlink A-MPDU 1703-1 corresponds to an indication of an
Implicit Block Acknowledgment and the second downlink A-MPDU 1703-2
corresponds to an indication of a Block Acknowledgment.
[0097] Based on the indication of the Implicit Block
Acknowledgment, the client station STA1 transmits a block
acknowledgment 1708 to the AP 14 in response to and upon receipt of
the second downlink A-MPDU 1703-2. In an embodiment, the client
station STA1 automatically transmits the block acknowledgment 1708
after a short interframe space (SIFS) period from the receipt of
the second downlink A-MPDU 1703-2. The client station STA2, based
on the indication of the Block Acknowledgment, waits for receipt of
a block acknowledgment request (BAR) 1710 from the AP 14 before
sending a block acknowledgment 1712 to the AP 14, in an embodiment.
The BAR 1710, in some embodiments, is transmitted using a same
bandwidth as the original OFDMA transmission 1704. For example, in
an embodiment, the OFDMA transmission 1704 occupies a bandwidth of
40 MHz (e.g., 2.times.20 MHz sub-channels) and the BAR 1710 is
duplicated across a same bandwidth. In various embodiments, the
client stations STA1 and STA2 transmit the block acknowledgments
1708 and 1712 to occupy a same sub-channel allocated for the
corresponding A-MPDU. In an embodiment, the client station
transmits the block acknowledgment using a transmission bandwidth
equal to the smaller of i) the OFDMA aggregated bandwidth and ii) a
smallest bandwidth that the client station is capable of
transmitting. In another embodiment, the client station transmits
the block acknowledgment using a transmission bandwidth equal to
n*20 MHz, where n is a smallest integer value such that the block
acknowledgment occupies the same bandwidth as the downlink
A-MPDU.
[0098] In some embodiments, the BAR 1710 and acknowledgment frames
1708 and 1712 are duplicated in each smallest bandwidth portion
(e.g., in each 20 MHz) of the entire bandwidth of the TXOP 1702.
For example, in an embodiment, the AP transmits a legacy OFDM data
unit as the BAR 1710 and the client stations transmit legacy OFDM
data units as the acknowledgment frames 1708 and 1712. In some
embodiments, the AP 14 allocates different sub-channels to
different client stations within a same TXOP.
[0099] FIG. 18 is a frame exchange 1800 between an AP 14 and a
plurality of client stations STA0, STA1, STA2 that includes
downlink OFDMA transmission of data from the AP to the plurality
client stations, according to an embodiment. The frame exchange
1800 includes frame exchanges 1801, 1811, and 1821 that occur
during a TXOP of the AP 14. During the frame exchange 1801, the AP
14 transmits a downlink OFDMA data unit 1802 (e.g., including
A-MPDUs) to the plurality of client stations STA2, STA1, and STA0.
In an embodiment, the downlink OFDMA data unit 1802 is generally
similar to the OFDMA data unit 602. In the embodiment illustrated
in FIG. 18, the AP 14 receives a block acknowledge 1804 (e.g., an
uplink OFDMA data unit) that does not include a block acknowledge
from the client station STA1 on a sub-channel 1805. In some
embodiments, the AP 14 allocates sub-channels based on the response
(e.g., block acknowledgments) to a previously transmitted downlink
OFDM data unit. In an embodiment, the AP 14 determines that the
sub-channel 1805 is busy or unavailable to the client station STA1
based on the omitted block acknowledgment. In an embodiment, when
the AP does not receive an uplink OFDM data unit in response to the
downlink OFDMA data unit, the AP does not send downlink OFDM data
units for the remainder of the TXOP to those client stations that
did not respond.
[0100] In an embodiment, the AP 14 transmits a downlink OFDMA data
unit having a non-contiguous sub-channel allocation. In an
embodiment, for example, based on the determination that an
acknowledgment to the previous OFDM data unit was not received, the
AP 14 transmits a downlink OFDMA data unit 1812 that omits an OFDM
data unit on the sub-channel 1805 during the frame exchange 1811.
In an embodiment, the AP 14 allocates the sub-channel 1805 to
another client station during the frame exchange 1821. In the
embodiment shown in FIG. 18, the AP 14 allocates the sub-channel
1805 to the client station STA2 during the frame exchange 1821.
[0101] FIG. 19 is a frame exchange 1900 between an AP and a
plurality of client stations STA0 and STA2 that includes downlink
OFDMA transmission of data from the AP to the plurality client
stations STA0 and STA2, according to an embodiment. In some
embodiments, the AP 14 determines whether sub-channels allocated
for a downlink OFDMA transmission are busy prior to the
transmission. The frame exchange 1900 is generally similar to the
frame exchange 1800, except that the AP 14 determines that a
sub-channel 1901 is busy, for example, as described above with
respect to FIG. 14. The AP 14 transmits a downlink OFDMA data unit
1902 that omits an OFDM data unit on the sub-channel 1901 during
the frame exchange 1900. In some embodiments, the AP 14 does not
send downlink OFDM data units on the sub-channel 1901 (e.g., the
busy sub-channels) for the remainder of the TXOP.
[0102] While an 80 MHz communication channel is allocated to the
client stations in the illustrated embodiment of FIG. 19, the AP 14
selects other sub-channel allocations (e.g., 60 MHz, 100 MHz, 120
MHz, 140 MHz, etc.) in other embodiments and/or scenarios. In an
embodiment, the AP 14 selects contiguous blocks of 40 MHz, 80 MHz,
or 160 MHz for an uplink MU-MIMO transmission. In some embodiments,
a physical layer clear channel assessment (PHY-CCA) provides an
idle/busy indication for each 20 MHz sub-channel of a communication
channel. In an embodiment, the PHY-CCA is redefined to provide at
least some sub-channel allocations.
[0103] FIG. 20 is a frame exchange 2000 between an AP 14 and a
plurality of client stations STA0 and STA1 that includes downlink
OFDMA transmission of data from the AP to the plurality client
stations STA0 and STA1, according to an embodiment. The frame
exchange 2000 is generally similar to the frame exchange 1900,
except that the AP 14 determines that a sub-channel 2001 is busy,
for example, as described above with respect to FIG. 14. The AP 14
transmits a downlink OFDMA data unit 2002 that omits an OFDM data
unit on the highest sub-channel 2001 during the frame exchange
1900. In some embodiments, the AP 14 does not send downlink OFDM
data units on the sub-channel 2001 (e.g., the busy sub-channels)
for the remainder of the TXOP. In the embodiment shown in FIG. 20,
the highest 20 MHz sub-channel of the 80 MHz channel is determined
to be busy, the second highest 20 MHz sub-channel is allocated to
the client station STA1, and a 40 MHz sub-channel that includes the
second lowest 20 MHz sub-channel and the lowest 20 MHz sub-channel
is allocated to STA0.
[0104] FIG. 21 is a frame exchange 2100 between an AP 14 and a
plurality of client stations STA0 and STA2 that includes downlink
OFDMA transmission of data from the AP 14 to the plurality client
stations STA0 and STA2, according to an embodiment. The frame
exchange 2100 is generally similar to the frame exchange 2000,
except that the AP 14 determines that a primary sub-channel 2101 of
a communication channel is busy during a scheduled service period,
for example, as described above with respect to FIG. 14. In an
embodiment, the AP 14 determines an availability of the sub-channel
2101 of the communication channel during the scheduled service
period based on an idle state during a point coordination function
interframe space (PIFS).
[0105] FIG. 22 is a frame exchange 2200 between an AP 14 and a
plurality of client stations STA1, STA2, and STA3 that includes
uplink OFDMA transmission of data with selected traffic
identifiers, according to an embodiment. The frame exchange 2200 is
generally similar to the frame exchange 900, except that the AP 14
selects a traffic class (TC) and/or an access category (AC) for
A-MPDUs, in an embodiment. The frame exchange 2200 includes a
scheduling frame 2202, an uplink OFDMA data unit 2204, and a block
acknowledgment 2206. In various embodiments and/or scenarios,
different stations transmit uplink OFDM data units having different
traffic classes and/or access categories within a same uplink
transmission. In an embodiment, the AP 14 selects data frames with
a same access category to be encapsulated within an A-MPDU.
[0106] In some embodiments, the AP 14 selects a primary access
category or traffic class (e.g., a primary AC/TC) for each client
station and provides an indication of the selected AC/TC within the
scheduling frame 2202. In an embodiment, the indication of the
selected AC/TC is included in a PHY SIG field or a control frame.
In an embodiment, for example, the scheduling frame 2202 includes
i) an identifier for each of the client stations STA1, STA2, and
STA3, ii) an indication of sub-channels on which each client
station should transmit for the OFDMA data unit 2204, and iii) an
indication of a traffic identifier that corresponds to the primary
AC/TC. In some embodiments, each client station has a different
traffic identifier, for example, the AP 14 selects traffic
identifiers TID1, TID3, and TID5 for the client stations STA1,
STA2, and STA3, respectively. In an embodiment, this TC allocation
is used in an uplink OFDMA exchange in a scheduled service period
(TWT service period) and EDCA TXOP. In some embodiments, all client
stations have a same traffic identifier, for example, the AP 14
selects traffic identifiers TID1 for the client stations STA1,
STA2, and STA3. In one embodiment, this TC allocation is used in an
uplink OFDMA exchange in an EDCA TXOP.
[0107] In an embodiment, the client station selects frames having
the primary AC/TC for transmission in the uplink OFDMA data unit
2204. In an embodiment, the client station selects frames from an
AC/TC different from the primary AC/TC if no frames from the
primary AC/TC are available (e.g., buffered for transmission). In
other embodiments, the scheduling frame 2202 does not include a
primary AC/TC and the client station selects the AC/TC for its own
uplink OFDM data unit of the OFDMA transmission 2204.
[0108] FIG. 23 is a frame exchange 2300 between an AP 14 and a
plurality of client stations STA1, STA2, and STA3 that includes
downlink OFDMA transmission of data with selected traffic
identifiers, according to an embodiment. The frame exchange 2300 is
generally similar to the frame exchange 1700, except that the AP 14
selects a traffic class and/or an access category for A-MPDUs, in
an embodiment. In an embodiment, the AP 14 selects traffic
identifiers TID0, TID7, and TID5 for the client stations STA1,
STA2, and STA3, respectively, and generates OFDM data units 2302-1,
2302-2, and 2302-3 having frames with the corresponding traffic
identifier. In an embodiment, this TC allocation is used in a
downlink OFDMA exchange in a scheduled service period (TWT service
period) and an EDCA TXOP. In some embodiments, all client stations
have a same traffic identifier, for example, the AP 14 selects the
traffic identifier TID1 for the client stations STA1, STA2, and
STA3. In one embodiment, this TC allocation is used in a downlink
OFDMA exchange in an EDCA TXOP.
[0109] FIG. 24 is a frame exchange 2400 between an AP 14 and a
plurality of client stations STA1, STA2, and STA3 that includes
both uplink OFDMA transmission of data and downlink OFDMA
transmission of data with selected traffic identifiers, according
to an embodiment. In some embodiments, the AP 14 provides an
indication of different traffic classes for both downlink OFDMA
data units and uplink OFDMA data units within a same TXOP. In the
embodiment shown in FIG. 24, the frame exchange 2400 includes a
downlink OFDMA data unit 2402, an uplink OFDMA data unit 2404, and
a block acknowledgment 2406. In an embodiment, the AP 14 generates
the OFDMA data unit 2402 to include i) an A-MPDU having a primary
AC/TC for each client station, as described above with respect to
FIG. 23, and ii) an indication of a primary AC/TC for a subsequent
OFDMA transmission by each client station. In an embodiment, each
client station generates an OFDM data unit of the uplink OFDMA data
unit 2404 to include MPDUs having the primary AC/TC indicated by
the OFDMA data unit 2402. In an embodiment, the AP 14 selects a
first primary AC/TC for the downlink OFDMA data unit 2402 and a
second primary AC/TC for the uplink OFDMA data unit 2404 where the
first primary AC/TC is different from the second primary AC/TC.
[0110] FIG. 25 is a diagram illustrating example uplink OFDMA
parameters 2500 for an OFDMA group of client stations, and
communications between an AP and client stations of the OFDMA group
that occur during time periods defined by the OFDMA parameters,
according to an embodiment. The example uplink OFDMA parameters
1500 in FIG. 25 include a start time parameter 1502 that indicates
a start of communications between the AP 14 and the client stations
25 of the OFDMA group, a service period 2504 that defines a time
duration of communications between the AP 14 and the client
stations 25 of the OFDMA group, and a scheduling interval 2506 that
defines an interval between two consecutive service periods for
communications between the AP 14 and the client stations 25 of the
OFDMA group. In the embodiment of FIG. 25, the service period 2504
includes a frame exchange between the AP 14 and the client stations
25 in the OFDMA group, in which an uplink OFDMA data unit is
transmitted from the client stations 25 in the OFDMA group to the
AP 14. For example, the service period 2504 includes the frame
exchange 900 of FIG. 9 or another suitable frame exchange as
described herein, in an embodiment. In various embodiments and/or
scenarios, at the beginning of a scheduled service period, the AP
starts a downlink OFDMA frame exchange or uplink frame exchange if
the AP 14 determines that the medium is idle for PIFS or after a
backoff procedure specific to the scheduled service period.
[0111] FIG. 26 is a flow diagram 2600 of an example method for
simultaneous communication with multiple communication devices in a
wireless local area network, according to an embodiment. In an
embodiment, the method 2600 is implemented by an AP in the WLAN,
according to an embodiment. With reference to FIG. 1, the method
2600 is implemented by the network interface 16 of the AP 14. For
example, the method 2600 is implemented by the MAC processing unit
18 and/or by the PHY processing unit 20 of the network interface
16, in an embodiment. In other embodiments, the method 2600 is
implemented by other components of the AP 14, or is implemented by
a suitable communication device other than the AP 14.
[0112] At block 2602, respective sub-channels of an orthogonal
frequency division multiplexing (OFDM) communication channel are
allocated to two or more second communication devices for
simultaneous OFDM transmission to the two or more second
communication devices. In an embodiment, a first sub-channel is
allocated to a first one of the two or more second communication
devices and a second sub-channel is allocated to a second one of
the two or more second communication devices.
[0113] At block 2604, respective downlink OFDM data units for the
two or more second communication devices using the corresponding
allocated sub-channels are generated. At block 2606, the downlink
OFDM data units are transmitted to the two or more second
communication devices using the corresponding allocated
sub-channels.
[0114] At block 2608, at least a first uplink OFDM data unit is
received from the first one of the two or more second communication
devices and a second uplink OFDM data unit is received from the
second one of the two or more second communication devices. The
first uplink OFDM data unit is transmitted from the first one of
the two or more second communication devices via the first
sub-channel allocated to the first one of the two or more second
communication devices in response to the corresponding downlink
OFDM data unit. The second uplink OFDM data unit is transmitted
from the second one of the two or more second communication devices
via the second sub-channel allocated to the second one of the two
or more second communication devices in response to the
corresponding downlink OFDM data unit.
[0115] FIG. 27 is a flow diagram 2700 of an example method for
simultaneous communication with multiple communication devices in a
wireless local area network, according to an embodiment. In an
embodiment, the method 2700 is implemented by a client station in
the WLAN, according to an embodiment. With reference to FIG. 1, the
method 2700 is implemented by the host processor 26 of the client
station 25-1. For example, the method 2700 is implemented by the
MAC processing unit 28 and/or by the PHY processing unit 29 of the
network interface 27, in an embodiment. In other embodiments, the
method 2700 is implemented by other components of the AP 14, or is
implemented by a suitable communication device other than the AP
14.
[0116] At block 2702, a downlink orthogonal frequency division
multiplexing (OFDM) data unit is received by a first communication
device from a second communication device via an OFDM communication
channel.
[0117] At block 2704, a sub-channel of the OFDM communication
channel on which the downlink OFDM data unit was transmitted by the
second communication device is identified.
[0118] At block 2706, an uplink OFDM data unit to be transmitted
via the sub-channel on which the downlink OFDM data unit was
transmitted is generated by the first communication device in
response to the downlink OFDM data unit.
[0119] At block 2708, the uplink OFDM data unit is automatically
transmitted to the second communication device via the sub-channel
on which the downlink OFDM data unit was transmitted.
[0120] FIG. 28 is a flow diagram 2800 of an example method for
simultaneous communication with multiple communication devices in a
wireless local area network, according to an embodiment. In an
embodiment, the method 2800 is implemented by a client station in
the WLAN, according to an embodiment. With reference to FIG. 1, the
method 2800 is implemented by the host processor 26 of the client
station 25-1. For example, the method 2800 is implemented by the
MAC processing unit 28 and/or by the PHY processing unit 29 of the
network interface 27, in an embodiment. In other embodiments, the
method 2800 is implemented by other components of the AP 14, or is
implemented by a suitable communication device other than the AP
14.
[0121] At block 2802, one or more downlink orthogonal frequency
division multiplexing (OFDM) data units are received by a first
communication device. The downlink OFDM data units are transmitted
by a second communication device via one or more respective
sub-channels of an OFDM communication channel.
[0122] At block 2804, the one or more sub-channels of the OFDM
communication channel on which the one or more downlink OFDMA data
units were transmitted are identified by the first communication
device.
[0123] At block 2806, a determination is made whether each of the
one or more sub-channels on which the one or more downlink OFDMA
data units were transmitted is busy. At block 2808, an uplink OFDM
data unit is generated for each sub-channel determined to be not
busy. At block 2810, each of the uplink OFDM data units is
transmitted to the second communication device via the
corresponding sub-channel.
[0124] Further aspects of the present invention relate to one or
more of the following clauses.
[0125] In an embodiment, a method for simultaneous communication
with multiple communication devices in a wireless local area
network includes: allocating, by a first communication device,
respective sub-channels of an orthogonal frequency division
multiplexing (OFDM) communication channel to two or more second
communication devices for simultaneous OFDM transmission to the two
or more second communication devices, including allocating a first
sub-channel to a first one of the two or more second communication
devices and a second sub-channel to a second one of the two or more
second communication devices; generating, by the first
communication device, respective downlink OFDM data units for the
two or more second communication devices using the corresponding
allocated sub-channels; transmitting, by the first communication
device, the downlink OFDM data units to the two or more second
communication devices using the corresponding allocated
sub-channels; and receiving, at the first communication device, at
least i) a first uplink OFDM data unit transmitted by the first one
of the two or more second communication devices in response to the
corresponding downlink OFDM data unit and ii) a second uplink OFDM
data unit transmitted by the second one of the two or more second
communication devices in response to the corresponding downlink
OFDM data unit, wherein the first uplink OFDM data unit is
transmitted from the first one of the two or more second
communication devices via the first sub-channel allocated to the
first one of the two or more second communication devices and the
second uplink OFDM data unit is transmitted from the second one of
the two or more second communication devices via the second
sub-channel allocated to the second one of the two or more second
communication devices.
[0126] In other embodiments, the method includes any suitable
combination of one or more of the following features.
[0127] The downlink OFDM data units include synchronization frames
and the uplink OFDM data units include aggregate media access
control protocol data units (A-MPDUs).
[0128] The synchronization frames include respective quality of
service indicators, and each of the A-MPDUs includes two or more
frames having the corresponding quality of service indicator.
[0129] The downlink OFDM data units are A-MPDUs and the uplink OFDM
data units are corresponding acknowledgments to the A-MPDUs.
[0130] Generating the downlink OFDM data units includes generating
a downlink orthogonal frequency division multiple access (OFDMA)
data unit that includes the downlink OFDM data units for the two or
more second communication devices, and receiving the first uplink
OFDM data unit and the second uplink OFDM data unit includes
receiving an uplink OFDMA data unit that includes the first uplink
OFDM data unit and the second uplink OFDM data unit.
[0131] The OFDM communication channel includes a multiple input,
multiple output (MIMO) communication channel. Transmitting the
downlink OFDM data units to the two or more second communication
devices includes transmitting the downlink OFDM data units via the
MIMO communication channel, the first sub-channel corresponding to
a first space time stream of the MIMO communication channel and the
second sub-channel corresponding to a second space time stream of
the MIMO communication channel. Receiving the first uplink OFDM
data unit and the second uplink OFDM data unit includes receiving
the first uplink OFDM data unit via the first space time stream and
receiving the second uplink OFDM data unit via the second space
time stream. The first uplink OFDM data unit and the second uplink
OFDM data unit are transmitted simultaneously from the first one of
the two or more second communication devices and the second one of
the two or more second communication devices, respectively.
[0132] The method further includes: determining an availability of
each sub-channel of the OFDM communication channel based on an idle
state during a point coordination function interframe space (PIFS),
and selecting the sub-channels of the OFDM communication channel
for allocation based on the determined idle state.
[0133] In another embodiment, a first communication device includes
a network interface device configured to: allocate respective
sub-channels of an orthogonal frequency division multiplexing
(OFDM) communication channel to two or more second communication
devices for simultaneous OFDM transmission to the two or more
second communication devices, the sub-channels including a first
sub-channel allocated to a first one of the two or more second
communication devices and a second sub-channel allocated to a
second one of the two or more second communication devices,
generate respective downlink OFDM data units for the two or more
second communication devices using the corresponding allocated
sub-channels, transmit the downlink OFDM data units to the two or
more second communication devices using the corresponding allocated
sub-channels, and receive, in response to the downlink OFDM data
units, at least a first uplink OFDM data unit from the first one of
the two or more second communication devices and a second uplink
OFDM data unit from the second one of the two or more second
communication devices, wherein the first uplink OFDM data unit is
transmitted from the first one of the two or more second
communication devices via the first sub-channel allocated to the
first one of the two or more second communication devices and the
second uplink OFDM data unit is transmitted from the second one of
the two or more second communication devices via the second
sub-channel allocated to the second one of the two or more second
communication devices.
[0134] The downlink OFDM data units include synchronization frames
and the uplink OFDM data units include aggregate media access
control protocol data units (A-MPDUs).
[0135] The synchronization frames include respective quality of
service indicators, and each of the A-MPDUs includes two or more
frames having the corresponding quality of service indicator.
[0136] The downlink OFDM data units are A-MPDUs and the uplink OFDM
data units are corresponding acknowledgments to the A-MPDUs.
[0137] The network interface is configured to: generate a downlink
orthogonal frequency division multiple access (OFDMA) data unit
that includes the downlink OFDM data units for the two or more
second communication devices, and receive an uplink OFDMA data unit
that includes the first uplink OFDM data unit and the second uplink
OFDM data unit.
[0138] The OFDM communication channel includes a multiple input,
multiple output (MIMO) communication channel, and the network
interface is configured to transmit the downlink OFDM data units
via the MIMO communication channel, the first sub-channel
corresponding to a first space time stream of the MIMO
communication channel and the second sub-channel corresponding to a
second space time stream of the MIMO communication channel, and
receive the first uplink OFDM data unit via the first space time
stream and the second uplink OFDM data unit via the second space
time stream, and the first uplink OFDM data unit and the second
uplink OFDM data unit are transmitted simultaneously from the first
one of the two or more second communication devices and the second
one of the two or more second communication devices,
respectively.
[0139] In an embodiment, a method for simultaneous communication
with multiple communication devices in a wireless local area
network includes: receiving, at a first communication device from a
second communication device, a downlink orthogonal frequency
division multiplexing (OFDM) data unit via an OFDM communication
channel, identifying, by the first communication device, a
sub-channel of the OFDM communication channel on which the downlink
OFDM data unit was transmitted by the second communication device,
generating, by the first communication device in response to the
downlink OFDM data unit, an uplink OFDM data unit to be transmitted
via the sub-channel on which the downlink OFDM data unit was
transmitted, automatically transmitting the uplink OFDM data unit
to the second communication device via the sub-channel on which the
downlink OFDM data unit was transmitted.
[0140] Automatically transmitting the uplink OFDM data unit
includes transmitting the uplink OFDM data unit after a short
interframe space (S IFS) time interval from receipt of the downlink
OFDM data unit without determining whether the sub-channel is busy
between the receipt of the downlink OFDM data unit and the
transmission of the uplink OFDM data unit.
[0141] The downlink OFDM data unit includes a synchronization frame
and the uplink OFDM data unit includes an aggregate media access
control protocol data unit (A-MPDU).
[0142] The method further includes: receiving, at the first
communication device via the sub-channel on which the downlink OFDM
data unit was transmitted, a block acknowledgment that indicates
receipt of the A-MPDU by the second communication device.
[0143] The method further includes receiving, at the first
communication device, a broadcast block acknowledgment having i) a
first device identifier corresponding to the first communication
device, ii) one or more other device identifiers corresponding to
one or more other communication devices, iii) a first bitmap that
indicates whether each MPDU in the A-MPDU was successfully received
by the second communication device, and iv) one or more other
bitmaps corresponding to the one or more other communication
devices.
[0144] The synchronization frame includes a quality of service
indicator, and generating the uplink OFDM data unit includes
generating the A-MPDU to include two or more MPDUs having the
corresponding quality of service indicator.
[0145] The downlink OFDM data unit includes an A-MPDU and the
uplink OFDM data unit includes an acknowledgment to the A-MPDU.
[0146] The uplink OFDM data unit is a portion of an orthogonal
frequency division multiple access (OFDMA) data unit.
[0147] The OFDM communication channel includes a MIMO communication
channel and the sub-channel includes a space time stream of the
MIMO communication channel. Receiving the downlink OFDM data unit
includes receiving the downlink OFDM data unit via the space time
stream.
[0148] In another embodiment, a first communication device includes
a network interface device configured to: receive, from a second
communication device, a downlink orthogonal frequency division
multiplexing (OFDM) data unit via an OFDM communication channel,
identify a sub-channel of the OFDM communication channel on which
the downlink OFDM data unit was transmitted by the second
communication device, generate, in response to the downlink OFDM
data unit, an uplink OFDM data unit to be transmitted via the
sub-channel on which the downlink OFDM data unit was transmitted,
and automatically transmit the uplink OFDM data unit to the second
communication device via the sub-channel on which the downlink OFDM
data unit was transmitted.
[0149] The network interface is configured to automatically
transmit the uplink OFDM data unit a short interframe space (S IFS)
time interval after receipt of the downlink OFDM data unit without
determining whether the sub-channel is busy between the receipt of
the downlink OFDM data unit and the transmission of the uplink OFDM
data unit.
[0150] The downlink OFDM data unit includes a synchronization frame
and the uplink OFDM data unit includes an aggregate media access
control protocol data unit (A-MPDU).
[0151] The network interface is configured to receive, via the
sub-channel on which the downlink OFDM data unit was transmitted, a
block acknowledgment that indicates receipt of the A-MPDU by the
second communication device.
[0152] The network interface is configured to receive a broadcast
block acknowledgment having i) a first device identifier
corresponding to the first communication device, ii) one or more
other device identifiers corresponding to one or more other
communication devices, iii) a first bitmap that indicates whether
each MPDU in the A-MPDU was successfully received by the second
communication device, and iv) one or more other bitmaps
corresponding to the one or more other communication devices.
[0153] The synchronization frame includes a quality of service
indicator, and the network interface is configured to generate the
A-MPDU to include two or more MPDUs having the corresponding
quality of service indicator.
[0154] The downlink OFDM data unit includes an A-MPDU and the
uplink OFDM data unit includes an acknowledgment to the A-MPDU.
[0155] The uplink OFDM data unit is a portion of an orthogonal
frequency division multiple access (OFDMA) data unit, and wherein
the OFDMA data unit further includes another OFDM data unit
simultaneously transmitted by a third communication device with the
uplink OFDM data unit.
[0156] The OFDM communication channel includes a MIMO communication
channel and the sub-channel includes a space time stream of the
MIMO communication channel. The network interface is configured to
receive the downlink OFDM data unit via the space time stream.
[0157] In an embodiment, a method for simultaneous communication
with multiple communication devices in a wireless local area
network includes: receiving, at a first communication device, one
or more downlink orthogonal frequency division multiplexing (OFDM)
data units transmitted by a second communication device via one or
more respective sub-channels of an OFDM communication channel;
identifying, by the first communication device, the one or more
sub-channels of the OFDM communication channel on which the one or
more downlink OFDMA data units were transmitted; determining, by
the first communication device, whether each of the one or more
sub-channels on which the one or more downlink OFDMA data units
were transmitted is busy; generating, by the first communication
device, an uplink OFDM data unit for each sub-channel determined to
be not busy; and transmitting each of the uplink OFDM data units to
the second communication device via the corresponding
sub-channel.
[0158] The one or more downlink OFDM data units include
synchronization frames and the one or more uplink OFDM data units
include one or more aggregate media access control protocol data
units (A-MPDU).
[0159] The method further includes: receiving, at the first
communication device via the sub-channels on which the one or more
uplink OFDM data units were transmitted, a block acknowledgment
that indicates receipt of the one or more A-MPDUs by the second
communication device.
[0160] The method further includes: receiving, at the first
communication device, a broadcast block acknowledgment having i) a
first device identifier corresponding to the first communication
device, ii) one or more other device identifiers corresponding to
one or more other communication devices, iii) one or more bitmaps
that indicate whether each of the one or more A-MPDUs was
successfully received by the second communication device, and iv)
one or more other bitmaps corresponding to the one or more other
communication devices.
[0161] The synchronization frame includes a quality of service
indicator, and generating the one or more uplink OFDM data units
includes generating the one or more A-MPDU to include only MPDUs
having the corresponding quality of service indicator.
[0162] The one or more downlink OFDM data units include one or more
A-MPDUs and the one or more uplink OFDM data units include one or
more acknowledgments to the one or more A-MPDU.
[0163] The one or more uplink OFDM data units are a portion of an
orthogonal frequency division multiple access (OFDMA) data
unit.
[0164] The OFDM communication channel includes a MIMO communication
channel and the one or more sub-channels include one or more space
time streams of the MIMO communication channel. Receiving the one
or more downlink OFDM data units includes receiving the one or more
downlink OFDM data unit via the corresponding space time
stream.
[0165] In another embodiment, a first communication device includes
a network interface device configured to: receive, from a second
communication device, one or more downlink orthogonal frequency
division multiplexing (OFDM) data units transmitted by a second
communication device via one or more respective sub-channels of an
OFDM communication channel, identify, by the first communication
device, the one or more sub-channels of the OFDM communication
channel on which the one or more downlink OFDMA data units were
transmitted, determine, by the first communication device, whether
each of the one or more sub-channels on which the one or more
downlink OFDMA data units were transmitted is busy; generate, by
the first communication device, an uplink OFDM data unit for each
sub-channel determined to be not busy, and transmit each of the
uplink OFDM data units to the second communication device via the
corresponding sub-channel.
[0166] The one or more downlink OFDM data units include one or more
synchronization frames and the one or more uplink OFDM data units
include one or more aggregate media access control protocol data
units (A-MPDU).
[0167] The network interface is configured to receive, via the
sub-channels on which the one or more uplink OFDM data units were
transmitted, a block acknowledgment that indicates receipt of the
one or more A-MPDUs by the second communication device.
[0168] The network interface is configured to receive a broadcast
block acknowledgment having i) a first device identifier
corresponding to the first communication device, ii) one or more
other device identifiers corresponding to one or more other
communication devices, iii) one or more bitmaps that indicate
whether each of the one or more A-MPDUs was successfully received
by the second communication device, and iv) one or more other
bitmaps corresponding to the one or more other communication
devices.
[0169] The synchronization frame includes a quality of service
indicator, and the network interface is configured to generate the
one or more uplink OFDM data units includes generating the one or
more A-MPDU to include only MPDUs having the corresponding quality
of service indicator.
[0170] The one or more downlink OFDM data units include one or more
A-MPDUs and the one or more uplink OFDM data units include one or
more acknowledgments to the one or more A-MPDU.
[0171] The one or more uplink OFDM data units are a portion of an
orthogonal frequency division multiple access (OFDMA) data
unit.
[0172] The OFDM communication channel includes a MIMO communication
channel and the one or more sub-channels include one or more space
time streams of the MIMO communication channel. The network
interface is configured to receive the one or more downlink OFDM
data unit via the corresponding space time stream.
[0173] 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
tangible, non-transitory computer readable memory such as a
magnetic disk, an optical disk, a RAM, a ROM, a flash memory, a
tape drive, etc. The software or firmware instructions may include
machine readable instructions that, when executed by one or more
processors, cause one or more processors to perform various
acts.
[0174] When implemented in hardware, the hardware may comprise one
or more of discrete components, one or more integrated circuits, an
application-specific integrated circuit (ASIC), a programmable
logic device (PLD), etc.
[0175] 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.
* * * * *