U.S. patent application number 17/101810 was filed with the patent office on 2021-04-29 for managing high volumes of space-time-streams in next generation extremely high throughput (eht) wi-fi systems.
The applicant listed for this patent is QUALCOMM Incorporated. Invention is credited to Jialing Li Chen, Bin Tian, Lochan Verma, Sameer Vermani, Lin Yang.
Application Number | 20210126700 17/101810 |
Document ID | / |
Family ID | 1000005329174 |
Filed Date | 2021-04-29 |
United States Patent
Application |
20210126700 |
Kind Code |
A1 |
Vermani; Sameer ; et
al. |
April 29, 2021 |
MANAGING HIGH VOLUMES OF SPACE-TIME-STREAMS IN NEXT GENERATION
EXTREMELY HIGH THROUGHPUT (EHT) WI-FI SYSTEMS
Abstract
This disclosure provides systems, methods, and apparatuses,
including computer programs encoded on computer storage media, for
managing high volumes of space-time-streams in Wi-Fi systems. An
access point (AP) may transmit packets including long training
field (LTF) sections using a number of space-time-streams greater
than eight. Mobile stations (STAs) in the system may or may not be
capable of processing this number of streams. The AP may modulate
an LTF section using a matrix with dimensions smaller than the
number of streams by using tone-interleaving or by performing
modulation with separate matrices in time and frequency. In some
other implementations, the AP may split the antennas for
transmission into groups, each group transmitting either different
packets in a subset of streams or a same packet in a subset of
tones. In further implementations, the AP may combine multiple
space-time-streams into a super stream that supports reception at
different types of STAs.
Inventors: |
Vermani; Sameer; (San Diego,
CA) ; Tian; Bin; (San Diego, CA) ; Chen;
Jialing Li; (San Diego, CA) ; Yang; Lin; (San
Diego, CA) ; Verma; Lochan; (Danville, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM Incorporated |
San Diego |
CA |
US |
|
|
Family ID: |
1000005329174 |
Appl. No.: |
17/101810 |
Filed: |
November 23, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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16154574 |
Oct 8, 2018 |
10848233 |
|
|
17101810 |
|
|
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|
62572168 |
Oct 13, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L 5/0048 20130101;
H04L 5/0044 20130101; H04J 2011/0009 20130101; H04J 11/003
20130101; H04W 84/12 20130101; H04L 27/2613 20130101; H04B 7/0691
20130101; H04B 7/0891 20130101; H04L 25/0204 20130101; H04L 5/0023
20130101 |
International
Class: |
H04B 7/08 20060101
H04B007/08; H04L 5/00 20060101 H04L005/00; H04B 7/06 20060101
H04B007/06; H04W 84/12 20060101 H04W084/12; H04L 27/26 20060101
H04L027/26; H04J 11/00 20060101 H04J011/00 |
Claims
1. A method for wireless communication, comprising: identifying a
number of space-time-streams for transmission of null data packet
(NDP) information in a set of tones, the NDP information comprising
a long training field (LTF) section that comprises orthogonal
frequency division multiplexing (OFDM) symbols; determining that
the number of space-time-streams is greater than a threshold number
of streams; transmitting a first subset of the NDP information
corresponding to a first subset of antennas, wherein a number of
the first subset of antennas is less than or equal to the threshold
number of streams; and transmitting a second subset of the NDP
information corresponding to a second subset of antennas, wherein a
number of the second subset of antennas is less than or equal to
the threshold number of streams.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application for Patent is a continuation of U.S.
patent application Ser. No. 16/154,574 filed Oct. 8, 2018, entitled
"Managing High Volumes of Space-Time-Streams In Next Generation
Extremely High Throughput (EHT) Wi-Fi Systems", which claims the
benefit of U.S. Provisional Patent Application No. 62/572,168 filed
Oct. 13, 2017, entitled "Managing High Volumes of
Space-Time-Streams in Next Generation Wi-Fi Systems," and assigned
to the assignee hereof. The disclosure of the prior Application is
considered part of and is incorporated by reference in this Patent
Application.
TECHNICAL FIELD
[0002] This disclosure relates to wireless communications, and more
specifically to a next generation extremely high throughput (EHT)
Wi-Fi system supporting a high volume of space-time-streams, such
as sixteen space-time-streams.
DESCRIPTION OF THE RELATED TECHNOLOGY
[0003] Wireless communications systems are widely deployed to
provide various types of communication content such as voice,
video, packet data, messaging, broadcast, and so on. These systems
may be multiple-access systems capable of supporting communication
with multiple users by sharing the available system resources (such
as time, frequency, and power). A wireless network, for example a
wireless local area network (WLAN) or Wi-Fi (i.e., Institute of
Electrical and Electronics Engineers (IEEE) 802.11) network may
include an access point (AP) that may communicate with one or more
stations (STAs) or mobile devices. The AP may be coupled to a
network, such as the Internet, and may enable a mobile device to
communicate via the network (or communicate with other devices
coupled to the AP). A wireless device may communicate with a
network device bi-directionally. For example, in a WLAN, a STA may
communicate with an associated AP via downlink and uplink
transmissions. The downlink (or forward link) may refer to the
communication link from the AP to the STA, and the uplink (or
reverse link) may refer to the communication link from the STA to
the AP.
SUMMARY
[0004] The systems, methods, and devices of this disclosure each
have several innovative aspects, no single one of which is solely
responsible for the desirable attributes disclosed herein.
[0005] One innovative aspect of the subject matter described in
this disclosure can be implemented in a method of wireless
communication. The method can include identifying a number of
space-time-streams for transmission of null data packet (NDP)
information in a set of tones, the NDP information containing a
long training field (LTF) section that includes orthogonal
frequency division multiplexing (OFDM) symbols, and determining
that the number of space-time-streams is greater than a threshold
number of streams. The method can further include transmitting a
first subset of the NDP information corresponding to a first subset
of antennas, where a number of the first subset of antennas is less
than or equal to the threshold number of streams, and transmitting
a second subset of the NDP information corresponding to a second
subset of the antennas, where a number of the second subset of
antennas is less than or equal to the threshold number of
streams.
[0006] Another innovative aspect of the subject matter described in
this disclosure can be implemented in an apparatus for wireless
communication. The apparatus can include means for identifying a
number of space-time-streams for transmission of NDP information in
a set of tones, the NDP information containing an LTF section that
includes OFDM symbols, and means for determining that the number of
space-time-streams is greater than a threshold number of streams.
The apparatus can further include means for transmitting a first
subset of the NDP information corresponding to a first subset of
antennas, where a number of the first subset of antennas is less
than or equal to the threshold number of streams, and means for
transmitting a second subset of the NDP information corresponding
to a second subset of the antennas, where a number of the second
subset of antennas is less than or equal to the threshold number of
streams.
[0007] Another innovative aspect of the subject matter described in
this disclosure can be implemented in another apparatus for
wireless communication. The apparatus can include a processor,
memory in electronic communication with the processor, and
instructions stored in the memory. The instructions can be operable
to cause the processor to identify a number of space-time-streams
for transmission of NDP information in a set of tones, the NDP
information containing an LTF section that includes OFDM symbols,
and determine that the number of space-time-streams is greater than
a threshold number of streams. The instructions can be further
operable to cause the processor to transmit a first subset of the
NDP information corresponding to a first subset of antennas, where
a number of the first subset of antennas is less than or equal to
the threshold number of streams, and transmit a second subset of
the NDP information corresponding to a second subset of the
antennas, where a number of the second subset of antennas is less
than or equal to the threshold number of streams.
[0008] Another innovative aspect of the subject matter described in
this disclosure can be implemented in a non-transitory
computer-readable medium for wireless communication. The
non-transitory computer-readable medium can include instructions
operable to cause a processor to identify a number of
space-time-streams for transmission of NDP information in a set of
tones, the NDP information containing an LTF section that includes
OFDM symbols, and determine that the number of space-time-streams
is greater than a threshold number of streams. The instructions can
be further operable to cause the processor to transmit a first
subset of the NDP information corresponding to a first subset of
antennas, where a number of the first subset of antennas is less
than or equal to the threshold number of streams, and transmit a
second subset of the NDP information corresponding to a second
subset of the antennas, where a number of the second subset of
antennas is less than or equal to the threshold number of
streams.
[0009] In some implementations, the first subset of the NDP
information can correspond to a first NDP and the second subset of
the NDP information can correspond to a second NDP different from
the first NDP. In some other implementations, the first subset of
the NDP information and the second subset of the NDP information
can both correspond to a same NDP, where the first subset of the
NDP information may be transmitted in a first subset of the set of
tones and the second subset of the NDP information may be
transmitted in a second subset of the set of tones.
[0010] In some implementations, transmitting the first subset of
the NDP information and transmitting the second subset of the NDP
information may further involve transmitting the first subset of
the NDP information and the second subset of the NDP information to
a station (STA), where the threshold number of streams may be based
on a capability of the STA. In some implementations, the capability
of the STA includes at least one of a total number of
space-time-streams the STA can process for a single NDP and a
number of LTFs the STA can process for the single NDP.
[0011] In some implementations, both the first subset of antennas
and the second subset of antennas can include at least one shared
antenna. In some implementations, the method, apparatuses, and
non-transitory computer-readable medium can include operations,
features, means, or instructions for mitigating a phase offset
between the first subset of the NDP information and the second
subset of the NDP information based on the at least one shared
antenna serving as a phase reference.
[0012] Another innovative aspect of the subject matter described in
this disclosure can be implemented in a method for wireless
communication. The method can include identifying a number of
space-time-streams for transmission of a packet, the packet
containing an LTF section that includes one or more OFDM symbols.
The method can further include selecting an orthogonal matrix for
modulation of the LTF section, where the size of a first and a
second dimension of the orthogonal matrix is less than the number
of space-time-streams used for transmission. Additionally, the
method can include modulating the LTF section over the
space-time-streams using the selected orthogonal matrix, and
transmitting the packet including the modulated LTF section over a
set of tones using the identified space-time-streams.
[0013] Another innovative aspect of the subject matter described in
this disclosure can be implemented in an apparatus for wireless
communication. The apparatus can include means for identifying a
number of space-time-streams for transmission of a packet, the
packet containing an LTF section that includes one or more OFDM
symbols. The apparatus can further include means for selecting an
orthogonal matrix for modulation of the LTF section, where a size
of a first and a second dimension of the orthogonal matrix is less
than the number of space-time-streams. Additionally, the apparatus
can include means for modulating the LTF section over the
space-time-streams using the selected orthogonal matrix and means
for transmitting the packet including the modulated LTF section
over a set of tones using the identified space-time-streams.
[0014] Another innovative aspect of the subject matter described in
this disclosure can be implemented in another apparatus for
wireless communication. The apparatus may include a processor,
memory in electronic communication with the processor, and
instructions stored in the memory. The instructions can be operable
to cause the processor to identify a number of space-time-streams
for transmission of a packet, the packet containing an LTF section
that includes one or more OFDM symbols. The instructions can be
further operable to cause the processor to select an orthogonal
matrix for modulation of the LTF section, where a size of a first
and a second dimension of the orthogonal matrix is less than the
number of space-time-streams. Additionally, the instructions can be
operable to cause the processor to modulate the LTF section over
the space-time-streams using the selected orthogonal matrix, and
transmit the packet including the modulated LTF section over a set
of tones using the identified space-time-streams.
[0015] Another innovative aspect of the subject matter described in
this disclosure can be implemented in a non-transitory
computer-readable medium for wireless communication. The
non-transitory computer-readable medium can include instructions
operable to cause a processor to identify a number of
space-time-streams for transmission of a packet, the packet
containing an LTF section that includes one or more OFDM symbols.
The instructions can further be operable to cause the processor to
select an orthogonal matrix for modulation of the LTF section,
where a size of a first and a second dimension of the orthogonal
matrix is less than the number of space-time-streams. Additionally,
the instructions can be operable to cause the processor to modulate
the LTF section over the space-time-streams using the selected
orthogonal matrix, and transmit the packet including the modulated
LTF section over a set of tones using the identified
space-time-streams.
[0016] In some implementations, modulating the LTF section over the
space-time-streams using the selected orthogonal matrix may include
operations, features, means, or instructions for spreading the
space-time-streams over the one or more OFDM symbols of the LTF
section using the selected orthogonal matrix.
[0017] In some implementations, modulating the LTF section over the
space-time-streams using the selected orthogonal matrix may include
operations, features, means, or instructions for modulating, for a
first subset of the set of tones, the LTF section over a first
subset of the space-time-streams using the selected orthogonal
matrix and modulating, for a second subset of the set of tones, the
LTF section over a second subset of the space-time-streams using a
second orthogonal matrix. In some implementations, modulating the
LTF section over the first subset of the space-time-streams using
the selected orthogonal matrix and modulating the LTF section over
the second subset of the space-time-streams using the second
orthogonal matrix may include operations, features, means, or
instructions for spreading the first subset of the
space-time-streams over the one or more OFDM symbols of the LTF
section for the first subset of the set of tones using the selected
orthogonal matrix and spreading the second subset of the
space-time-streams over the one or more OFDM symbols of the LTF
section for the second subset of the set of tones using the second
orthogonal matrix. Additionally, in some implementations, the first
subset of the space-time-streams and the second subset of the
space-time-streams are spread such that a STA receiving the packet
interpolates the spread first subset of the space-time-streams and
the spread second subset of the space-time-streams to determine the
first subset of the space-time-streams over the one or more OFDM
symbols of the LTF section for the second subset of the set of
tones and the second subset of the space-time-streams over the one
or more OFDM symbols of the LTF section for the first subset of the
set of tones.
[0018] In some implementations, both the first subset of the
space-time-streams and the second subset of the space-time-streams
include at least one shared space-time-stream. Additionally, or
alternatively, in some implementations, the selected orthogonal
matrix and the second orthogonal matrix may be the same.
[0019] In some implementations, the method, apparatuses, and
non-transitory computer-readable medium can include operations,
features, means, or instructions for grouping the set of tones into
a set of tone blocks, selecting a third orthogonal matrix for
modulation of the space-time-streams within each of the set of tone
blocks, and modulating, for each of the set of tone blocks, the
space-time-streams using the selected third orthogonal matrix to
obtain orthogonal signals in neighboring tones of the set of tones.
In some implementations, modulating the space-time-streams using
the selected third orthogonal matrix can include operations,
features, means, or instructions for spreading the
space-time-streams over the set of tones using the selected third
orthogonal matrix. In some implementations, a first dimension of
the selected third orthogonal matrix multiplied by the first
dimension of the selected orthogonal matrix may be greater than or
equal to the number of space-time-streams, where the first
dimension of the selected third orthogonal matrix may be less than
the number of space-time-streams.
[0020] In some implementations, the LTF section can include a
compressed LTF section and the set of tones can include a number of
tones that is less than a number of tones corresponding to an
uncompressed LTF section.
[0021] Another innovative aspect of the subject matter described in
this disclosure can be implemented in a method of wireless
communication. The method can include identifying a number of
space-time-streams for transmission of a packet and determining
that the number of the space-time-streams is greater than a
threshold number of space-time-streams. The method can further
include combining a number of the space-time-streams to form one or
more super streams, where a total number of the one or more super
streams and any remaining uncombined space-time-streams is less
than or equal to the threshold number of streams, and transmitting
the packet over a set of tones using the one or more super streams
and the remaining uncombined space-time-streams.
[0022] Another innovative aspect of the subject matter described in
this disclosure can be implemented in an apparatus for wireless
communication. The apparatus can include means for identifying a
number of space-time-streams for transmission of a packet and means
for determining that the number of the space-time-streams is
greater than a threshold number of space-time-streams. The
apparatus can further include means for combining a number of the
space-time-streams to form one or more super streams, where a total
number of the one or more super streams and any remaining
uncombined space-time-streams is less than or equal to the
threshold number of streams, and means for transmitting the packet
over a set of tones using the one or more super streams and the
remaining uncombined space-time-streams.
[0023] Another innovative aspect of the subject matter described in
this disclosure can be implemented in another apparatus for
wireless communication. The apparatus can include a processor,
memory in electronic communication with the processor, and
instructions stored in the memory. The instructions can be operable
to cause the processor to identify a number of space-time-streams
for transmission of a packet and determine that the number of the
space-time-streams is greater than a threshold number of
space-time-streams. The instructions can be further operable to
cause the processor to combine a number of the space-time-streams
to form one or more super streams, where a total number of the one
or more super streams and any remaining uncombined
space-time-streams is less than or equal to the threshold number of
streams, and transmit the packet over a set of tones using the one
or more super streams and the remaining uncombined
space-time-streams.
[0024] Another innovative aspect of the subject matter described in
this disclosure can be implemented in a non-transitory
computer-readable medium for wireless communication. The
non-transitory computer-readable medium can include instructions
operable to cause a processor to identify a number of
space-time-streams for transmission of a packet and determine that
the number of the space-time-streams is greater than a threshold
number of space-time-streams. The instructions can be further
operable to cause the processor to combine a number of the
space-time-streams to form one or more super streams, where a total
number of the one or more super streams and any remaining
uncombined space-time-streams is less than or equal to the
threshold number of streams, and transmit the packet over a set of
tones using the one or more super streams and the remaining
uncombined space-time-streams.
[0025] In some implementations, each of the one or more super
streams may be designed such that a first type of STAs receive the
super stream as a single space-time-stream and a second type of
STAs receive the super stream as a set of separate
space-time-streams. In these implementations, the first type of
STAs can include STAs capable of receiving a total number of
space-time-streams equal to or less than the threshold number of
space-time-streams and the second type of STAs can include STAs
capable of receiving a total number of space-time-streams greater
than the threshold number of space-time-streams.
[0026] In some implementations, the packet can include an LTF
section. In these implementations, the method, apparatuses, and
non-transitory computer-readable medium can include operations,
features, means, or instructions for selecting an orthogonal matrix
for modulation of the LTF section, where each row of the selected
orthogonal matrix corresponds to a super stream, an uncombined
space-time-stream, or a set of combined space-time-streams.
[0027] In some implementations, a first row of the selected
orthogonal matrix can correspond to a set of combined
space-time-streams. In these implementations, the method,
apparatuses, and non-transitory computer-readable medium can
include operations, features, means, or instructions for spreading
a first space-time-stream of the set of combined space-time-streams
over the LTF section for a first subset of the set of tones using
the first row of the selected orthogonal matrix and spreading a
second space-time-stream of the set of combined space-time-streams
over the LTF section for a second subset of the set of tones using
the first row of the selected orthogonal matrix.
[0028] Another innovative aspect of the subject matter described in
this disclosure can be implemented in a method of wireless
communication. The method can include identifying a number of
space-time-streams for transmission of NDP information in a set of
tones, the NDP information containing an LTF section that includes
one or more OFDM symbols, and determining that the number of the
space-time-streams is greater than a threshold number of streams.
The method can further include grouping the set of tones into a
number of tone blocks, modulating an NDP including the NDP
information across the one or more OFDM symbols of the LTF section
using a first orthogonal matrix and across each of the tone blocks
using a second orthogonal matrix, and transmitting the modulated
NDP over the set of tones using the identified
space-time-streams.
[0029] Another innovative aspect of the subject matter described in
this disclosure can be implemented in an apparatus for wireless
communication. The apparatus can include means for identifying a
number of space-time-streams for transmission of NDP information in
a set of tones, the NDP information containing an LTF section that
includes one or more OFDM symbols, and means for determining that
the number of the space-time-streams is greater than a threshold
number of streams. The apparatus can include further means for
grouping the set of tones into a number of tone blocks, means for
modulating an NDP including the NDP information across the one or
more OFDM symbols of the LTF section using a first orthogonal
matrix and across each of the tone blocks using a second orthogonal
matrix, and means for transmitting the modulated NDP over the set
of tones using the identified space-time-streams.
[0030] Another innovative aspect of the subject matter described in
this disclosure can be implemented in another apparatus for
wireless communication. The apparatus can include a processor,
memory in electronic communication with the processor, and
instructions stored in the memory. The instructions can be operable
to cause the processor to identify a number of space-time-streams
for transmission of NDP information in a set of tones, the NDP
information containing an LTF section that includes one or more
OFDM symbols, and determine that the number of the
space-time-streams is greater than a threshold number of streams.
The instructions can be further operable to cause the processor to
group the set of tones into a number of tone blocks, modulate an
NDP including the NDP information across the one or more OFDM
symbols of the LTF section using a first orthogonal matrix and
across each of the tone blocks using a second orthogonal matrix,
and transmit the modulated NDP over the set of tones using the
identified space-time-streams.
[0031] Another innovative aspect of the subject matter described in
this disclosure can be implemented in a non-transitory
computer-readable medium for wireless communication. The
non-transitory computer-readable medium can include instructions
operable to cause a processor to identify a number of
space-time-streams for transmission of NDP information in a set of
tones, the NDP information containing an LTF section that includes
one or more OFDM symbols, and determine that the number of the
space-time-streams is greater than a threshold number of streams.
The instructions can be further operable to cause the processor to
group the set of tones into a number of tone blocks, modulate an
NDP including the NDP information across the one or more OFDM
symbols of the LTF section using a first orthogonal matrix and
across each of the tone blocks using a second orthogonal matrix,
and transmit the modulated NDP over the set of tones using the
identified space-time-streams.
[0032] Details of one or more implementations of the subject matter
described in this disclosure are set forth in the accompanying
drawings and the description below. Other features, aspects, and
advantages will become apparent from the description, the drawings
and the claims. Note that the relative dimensions of the following
figures may not be drawn to scale.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] FIGS. 1 and 2 show examples of wireless communications
systems that support high volumes of space-time-streams.
[0034] FIG. 3 shows an example of techniques for performing long
training field (LTF) modulation in a wireless communications system
that supports high volumes of space-time-streams.
[0035] FIG. 4 shows an example of techniques for transmitting a
null data packet (NDP) in a wireless communications system that
supports high volumes of space-time-streams.
[0036] FIG. 5 shows an example of space-time-stream and super
stream transmissions in a wireless communications system that
supports high volumes of space-time-streams.
[0037] FIG. 6 shows a block diagram of an example system including
an access point (AP) that supports high volumes of
space-time-streams.
[0038] FIGS. 7-10 show flowcharts illustrating example methods for
managing high volumes of space-time-streams in Next Generation
Wi-Fi systems.
[0039] Like reference numbers and designations in the various
drawings indicate like elements.
DETAILED DESCRIPTION
[0040] The following description is directed to certain
implementations for the purposes of describing the innovative
aspects of this disclosure. However, a person having ordinary skill
in the art will readily recognize that the teachings herein can be
applied in a multitude of different ways. The described
implementations may be implemented in any device, system or network
that is capable of transmitting and receiving RF signals according
to any of the IEEE 16.11 standards, or any of the IEEE 802.11
standards, the Bluetooth.RTM. standard, code division multiple
access (CDMA), frequency division multiple access (FDMA), time
division multiple access (TDMA), Global System for Mobile
communications (GSM), GSM/General Packet Radio Service (GPRS),
Enhanced Data GSM Environment (EDGE), Terrestrial Trunked Radio
(TETRA), Wideband-CDMA (W-CDMA), Evolution Data Optimized (EV-DO),
1.times.EV-DO, EV-DO Rev A, EV-DO Rev B, High Speed Packet Access
(HSPA), High Speed Downlink Packet Access (HSDPA), High Speed
Uplink Packet Access (HSUPA), Evolved High Speed Packet Access
(HSPA+), Long Term Evolution (LTE), AMPS, or other known signals
that are used to communicate within a wireless, cellular or
internet of things (IOT) network, such as a system utilizing 3G, 4G
or 5G, or further implementations thereof, technology.
[0041] Techniques are disclosed for wireless devices to support a
high volume of space-time-streams (for example, greater than eight
space-time-streams). In a wireless communications system, an access
point (AP) may perform spatial multiplexing to improve throughput
to one or more mobile stations (STAs). According to these
techniques, the AP may identify a number of space-time-streams,
which may alternatively be referred to as spatial streams or,
simply, streams, for spatial multiplexing, and may transmit a
packet to one or more STAs using the identified streams. The packet
may include at least a long training field (LTF) section for the
purposes of channel estimation, the LTF section including one or
more orthogonal frequency division multiplexing (OFDM) symbols.
Additionally, the AP may perform a modulation process prior to
transmitting the packet in order to improve separation of the
space-time-streams at a receiving STA.
[0042] An AP may perform modulation during the LTF section using
one or more P matrices, which may be examples of square orthogonal
matrices. A first dimension of each P matrix may correspond to LTF
symbols or indices, while the second dimension may correspond to
space-time-streams. In some implementations, an AP may select a
P-matrix for modulation with dimensions smaller than the number of
space-time-streams being transmitted. The AP may perform the
modulation process on the LTF section using the selected
P-matrix.
[0043] In some implementations, the AP may modulate the LTF section
with the smaller P-matrix using tone-interleaving. For example, the
AP may modulate the LTF section over a subset of the
space-time-streams in a first set of tones using the P-matrix. The
AP may additionally modulate the LTF section over a second subset
of the space-time-streams in a second set of tones (for example,
either using the same P-matrix or a different P-matrix). In other
implementations, the AP may modulate space-time-streams over the
LTF symbols with the smaller P-matrix and use a second orthogonal
matrix for modulating the space-time-streams over frequency to
ensure orthogonality. For example, the AP may modulate the LTF
section across OFDM symbols using the selected P-matrix, and may
select the same or a different orthogonal matrix for modulating
across blocks of frequency tones. In some other implementations,
rather than selecting a smaller P-matrix, the AP may be configured
to select a P-matrix equal in size to the number of
space-time-streams (for example, the AP may use a 16.times.16
P-matrix for modulating sixteen LTF symbols over sixteen
space-time-streams).
[0044] Additionally, or alternatively, the AP may manage STAs with
lesser sounding capabilities than the number of space-time-streams.
For example, some types of STAs may not be configured to process
spatial multiplexing with a high volume of space-time-streams (such
as sixteen streams) during the sounding process. In some
implementations, and AP may employ dual/tone-interleaved NDP
approaches or frequency-domain orthogonal matrix modulation
approaches. In some implementations, an AP transmitting a packet,
such as a null data packet (NDP), with a high volume of
space-time-streams to such a STA may transmit some of the NDP
information in a first NDP using a first set of antennas and some
of the NDP information in a second NDP using a second set of
antennas. In some other implementations, the AP may transmit a
single NDP, but may transmit the NDP in a first set of tones using
a first set of antennas and in a second set of tones using a second
set of antennas. These two sets of tones may be interleaved in the
frequency domain. Antennas, as referred to above, may be examples
of physical antennas, antenna ports, or virtual antennas. In yet
other implementations, the AP may modulate the LTF section of the
NDP in the time domain using a first orthogonal matrix and in the
frequency domain using a second orthogonal matrix.
[0045] In some wireless communications systems, the AP may transmit
packets both to the types of STAs not configured to process spatial
multiplexing with a high volume of space-time-streams and to the
types of STAs configured to process spatial multiplexing with a
high volume of space-time-streams. In some implementations, STAs
capable of processing up to eight space-time-streams or eight LTFs
in sounding may be referred to as "legacy" STAs, while STAs capable
of processing up to sixteen space-time-streams or sixteen LTFs in
sounding--that is, a high volume of space-time-streams or LTFs--may
be referred to as extremely high throughput (EHT) STAs or Next
Generation STAs. In such systems, the AP may perform aggregation of
space-time-streams into super streams, and may reduce the number of
LTFs corresponding to a high number of streams by implementing a
number of super-stream techniques. For example, in some
implementations, the AP may share a channel estimation resource
(e.g., a row of a P-matrix) during modulation between different
streams across tones. Such streams that share a channel estimation
resource may constitute a super-stream. STAs not configured for the
high volume of space-time-streams may receive each super stream as
if it is a single space-time-stream, while STAs configured for the
high volume of space-time-streams may separately receive each
space-time-stream contained within a super stream. In some
implementations, the AP may utilize downlink multi-user,
multiple-input, multiple-output (DL MU-MIMO) techniques to transmit
a high volume of spatial streams to STAs with lesser reception
capabilities. In some other implementations, super streams may be
implemented for uplink transmissions as well. STAs configured to
support the high volume of space-time-streams may transmit to an AP
in one or more super streams, where each super stream includes
multiple space-time-streams transmitted in the uplink. STAs not
configured to support the high volume of space-time-streams may
transmit simultaneously (for example, using single
space-time-streams), and may not identify the presence of the
multiple streams within each uplink super stream.
[0046] Particular implementations of the subject matter described
in this disclosure can be implemented to realize one or more of the
following potential advantages. Specifically, the proposed
techniques allow for an AP to transmit packets to one or more STAs
using a high volume of space-time-streams (for example, greater
than eight space-time-streams). Transmitting using a high volume of
space-time-streams increases spatial multiplexing, resulting in an
improved spectral efficiency. An AP configured to perform the
proposed techniques may therefore increase the number of bits it
can transmit in given time and frequency intervals, increasing
network throughputs and reducing latency in the Next Generation
Wi-Fi system. Additionally, the proposed techniques allow for an AP
using the high volume of space-time-streams to transmit
simultaneously to STAs with different capabilities. For example,
the AP may utilize its full spatial multiplexing capability, even
in systems including STAs not configured to support the high volume
of spatial streams (for example, by implementing super streams).
This may improve the usage rate of the space-time-streams and allow
the AP to efficiently utilize the channel, regardless of the
configurations of the receiving STAs. Another potential advantage
of the proposed techniques is the ability for an AP or STA to use a
P-matrix of a smaller dimension than the number of
space-time-streams in a downlink or uplink packet, which may lead
to easier implementations (e.g., implementations that are less
complex with respect to processing or memory resources).
[0047] FIG. 1 shows an example of a wireless communications system
100 that supports high volumes of space-time-streams. The system
may be an example of a wireless local area network (WLAN) (such as
a Next Generation, Next Big Thing (NBT), Ultra-High Throughput
(UHT) or EHT Wi-Fi network) configured in accordance with various
aspects of the present disclosure. As described herein, the terms
Next Generation, NBT, UHT, and EHT may be considered synonymous and
may each correspond to a Wi-Fi network supporting a high volume of
space-time-streams (with one non-limiting example including sixteen
streams). The wireless communications system 100 may include an AP
105 and multiple associated STAs 115, which may represent devices
such as mobile stations, personal digital assistant (PDAs), other
handheld devices, netbooks, notebook computers, tablet computers,
laptops, display devices (such as TVs, computer monitors, etc.),
printers, etc. The AP 105 and the associated STAs 115 may represent
a basic service set (BSS) or an extended service set (ESS). The
various STAs 115 in the network may communicate with one another
through the AP 105 or directly via device-to-device (D2D)
communication. Also shown is a coverage area 110 of the AP 105,
which may represent a basic service area (BSA) of the wireless
communications system 100. An extended network station (not shown)
associated with the wireless communications system 100 may be
connected to a wired or wireless distribution system that may allow
multiple APs 105 to be connected in an ESS. In some
implementations, an AP 105 may transmit to one or more STAs 115
using a high volume of space-time-streams (for example, greater
than eight space-time-streams, which also may be referred to as
spatial streams or, simply, streams). The AP 105 may perform
modulation and transmission to manage this high volume of
space-time-streams, as well as to support both STAs 115 that
support high volumes of streams and STAs 115 that do not support
high volumes of streams.
[0048] Although not shown in FIG. 1, a STA 115 may be located at
the intersection of more than one coverage area 110 and may
associate with more than one AP 105. A single AP 105 and an
associated set of STAs 115 may be referred to as a BSS. An ESS is a
set of connected BSSs. A distribution system (not shown) may be
used to connect APs 105 in an ESS. In some implementations, the
coverage area 110 of an AP 105 may be divided into sectors (also
not shown). The wireless communications system 100 may include APs
105 of different types (such as metropolitan area APs, home network
APs, etc.) with varying and overlapping coverage areas 110. The AP
105 may communicate with one or more STAs 115 within the coverage
area 110 corresponding to the AP 105. For example, the AP 105 may
communicate with a STA 115 over a communication link 120, where
transmissions from the AP 105 to the STA 115 may be referred to as
downlink transmissions and transmissions from the STA 115 to the AP
105 may be referred to as uplink transmissions. Additionally, two
STAs 115 also may communicate directly via a direct wireless link
125 regardless of whether both STAs 115 are in the same coverage
area 110. Examples of direct wireless links 125 may include Wi-Fi
Direct connections, Wi-Fi Tunneled Direct Link Setup (TDLS) links,
and other group connections. STAs 115 and APs 105 may communicate
according to the WLAN radio and baseband protocol for physical and
MAC layers from IEEE 802.11 and versions including, but not limited
to, 802.11b, 802.11g, 802.11a, 802.11n, 802.11ac, 802.11ad,
802.11ah, 802.11ax, and subsequent versions. In some other
implementations, peer-to-peer connections or ad hoc networks may be
implemented within the wireless communications system 100.
[0049] In some implementations, a STA 115 (or an AP 105) may be
detectable by a central AP 105, but not by other STAs 115 in the
coverage area 110 of the central AP 105. For example, one STA 115
may be at one end of the coverage area 110 of the central AP 105
while another STA 115 may be at the other end. Thus, both STAs 115
may communicate with the AP 105, but may not receive the
transmissions of the other. This may result in colliding
transmissions for the two STAs 115 in a contention-based
environment (such as an environment or system supporting
carrier-sense multiple access with collision avoidance (CSMA/CA))
because the STAs 115 may not refrain from transmitting on top of
each other. A STA 115 whose transmissions are not identifiable, but
that is within the same coverage area 110 may be known as a hidden
node. CSMA/CA may be supplemented by the exchange of a
request-to-send (RTS) packet transmitted by a sending STA 115 (or
AP 105) and a clear-to-send (CTS) packet transmitted by the
receiving STA 115 (or AP 105). This may alert other devices within
range of the sender and receiver not to transmit for the duration
of the primary transmission. Thus, RTS/CTS may help mitigate a
hidden node problem.
[0050] The various systems and methods described may provide means
to support a high volume of space-time-streams present in Wi-Fi
communications. In some wireless communications systems 100, an AP
105 may transmit a packet containing an LTF section using a given
number of streams, where a STA 115 may receive and further decode
the packet. For improved spectral efficiency, the AP 105 may
transmit using up to sixteen streams (and, correspondingly using up
to sixteen LTFs), which may be referred to as a high volume of
space-time-streams. In some implementations, the AP 105 may
modulate the LTF section using a square orthogonal matrix with
dimensions smaller than the number of streams or LTF indices. For
example, the AP 105 may store an 8.times.8 matrix in memory for
packet modulation and may use this 8.times.8 matrix for modulating
when transmitting with any number of space-time-streams. Using a
smaller P-matrix for modulation may allow the AP 105 to store fewer
matrices in memory, and may support backwards compatibility with
STAs 115 or other APs 105 that do not support a high volume of
space-time-streams.
[0051] In some implementations, a STA 115 receiving the packet may
be unable to process a large number of space-time-streams (for
example, greater than eight space-time-streams) due to one or more
capabilities of the STA 115. In these implementations, the AP 105
may modulate the LTF section using an orthogonal matrix with
dimensions less than the number of tone-interleaved streams, or by
utilizing separate matrices to modulate the LTF over for example,
time and frequency resources. Additionally, or alternatively, the
AP 105 may identify subsets of antennas to sound in separate
attempts, where each group of antennas may transmit the packet
across different subsets of tones. The AP 105 may further combine
the number of space-time-streams to create a super stream to
support reception at various different types of STAs 115. For
example, implementing super streams may allow for the AP 105 to
obtain the spectral efficiency benefits provided by a high volume
of space-time-streams even in a wireless communications system 100
where some STAs 115 are incapable of processing this high volume of
space-time-streams.
[0052] FIG. 2 shows an example of a wireless communications system
200 that supports high volumes of space-time-streams. The wireless
communications system 200 may be an example of a Next Generation or
EHT Wi-Fi system, and may include an AP 105-a, a STA 115-a, and a
coverage area 110-a, which may be examples of the corresponding
components described with respect to FIG. 1. The AP 105-a may
transmit a packet 210 on the downlink 205 to the STA 115-a using a
number of space-time-streams. The packet may include an LTF section
215.
[0053] Some configurations of wireless communications systems (for
example, "legacy" systems) may support up to eight
space-time-streams or spatial streams for simultaneous
communication, which may represent the total number of streams
across all users or STAs 115-a served by a same AP 105. However,
some Next Generation or EHT Wi-Fi systems, such as a wireless
communications system 200, may support configurations to manage a
higher volume of space-time-streams (that is, higher than the
legacy systems). For example, the wireless communications system
200 may include support for a number of space-time-streams larger
than eight (such as sixteen space-time-streams). The AP 105-a, the
STA 115-a, or both may include capabilities for processing up to
sixteen space-time-streams at a same instant in time (for example,
during a same transmission time interval (TTI)).
[0054] To communicate information contained in the packet 210 to
the STA 115-a, the AP 105-a may employ methods to modulate the LTF
section 215 prior to transmission. The modulation process for the
LTF section 215 may be part of a larger modulation procedure for
the entire packet 210. The LTF section 215 may span one or more
OFDM symbols and may include information used for initial channel
estimation at the STA 115-a. For example, the LTF section 215 may
include a number of long training symbols (i.e., LTF symbols) and a
cyclic prefix. A STA 115-a receiving the LTF section 215 may use
the repeated long training symbols for frequency offset estimation,
channel estimation, etc. The AP 105-a may select an orthogonal
matrix (for example, a P-matrix) to modulate the LTF section 215
over a number of space-time-streams. This modulation process may
involve spreading each space-time-stream over the time and
frequency resources allocated for the LTF section 105-a. One
example of a 6.times.6 P-matrix may be an orthogonal discrete
Fourier transform (DFT) matrix used in signal processing
methods:
P 6 .times. 6 = [ 1 - 1 1 1 1 - 1 1 - w 1 w 2 w 3 w 4 - w 5 1 - w 2
w 4 w 6 w 8 - w 10 1 - w 3 w 6 w 9 w 12 - w 15 1 - w 4 w 8 w 12 w
16 - w 20 1 - w 5 w 10 w 15 w 20 - w 25 ] ##EQU00001##
[0055] In the above example, the constant w may be defined as w=exp
(-j2.pi./6). The dimensions of the P-matrix may be based on the
number of LTF indices and the number of space-time-streams. For
example, each column of the matrix may correspond to an LTF index,
and each row of the matrix may correspond to a space-time-stream.
The DFT P-matrix may multiply the frequency-domain LTF sequence for
the LTF section 215 to obtain LTF sequences spread across the
time-domain for each of the space-time-streams. A STA 115-a
receiving the LTF symbols (for example, for all of the spatial
streams) may separate the different spatial streams based on the
orthogonality of the P-matrix used for modulation.
[0056] An AP 105-a configured to use higher volumes of
space-time-streams may store P-matrices to manage these higher
numbers of streams. For example, an AP 105-a in a Next Generation
or EHT Wi-Fi system may store a variety of orthogonal matrices (for
example, a 10.times.10 matrix, a 12.times.12 matrix, a 14.times.14
matrix, a 16.times.16 matrix, etc.) for handling larger numbers of
space-time-streams. These larger P-Matrices extended for higher
dimensions may be commonly defined across EHT wireless
communications systems 200. In some implementations, these matrices
may be composed of smaller P-matrices as sub-components. In one
example, a 12.times.12 P-matrix may be constructed using
constituent 6.times.6 orthogonal P-matrices, such that:
P 1 .times. 2 .times. 1 .times. 2 = [ P 6 .times. 6 P 6 .times. 6 P
6 .times. 6 - P 6 .times. 6 ] . ##EQU00002##
[0057] In another example, a 16.times.16 matrix may be constructed
using 8.times.8 orthogonal P-matrices as building blocks:
P 1 .times. 6 .times. 1 .times. 6 = [ P 8 .times. 8 P 8 .times. 8 P
8 .times. 8 - P 8 .times. 8 ] . ##EQU00003##
[0058] Additional higher-dimensional matrices (for example,
matrices larger than 8.times.8) may be constructed using similar
methods. For example, an AP 105-a may store a 10.times.10 matrix, a
14.times.14 matrix, or both constructed by performing
element-by-element multiplication on existing (that is, smaller)
matrices or on arrays. One example of code for constructing such a
10.times.10 P-matrix includes:
z=exp(jmath*2*pi/10);
first row=[1 -1 1 1 1 -1 1 1 1 -1];
vector=[1 z z{circumflex over ( )}2 z{circumflex over ( )}3
z{circumflex over ( )}4 z{circumflex over ( )}5 z{circumflex over (
)}6 z{circumflex over ( )}7 z{circumflex over ( )}8 z{circumflex
over ( )}9];
P=[first row; first row.*vector; first row.*(vector.{circumflex
over ( )}2); first row.*(vector.{circumflex over ( )}3); first
row.*(vector.{circumflex over ( )}4); first
row.*(vector.{circumflex over ( )}5); first
row.*(vector.{circumflex over ( )}6); first
row.*(vector.{circumflex over ( )}7); first
row.*(vector.{circumflex over ( )}8); first
row.*(vector.{circumflex over ( )}9);],
where the "first row" array can include any values and the P-matrix
may maintain orthogonality (although an array of all "1 s" may
result in a spectral line) and ".*" corresponds to the
element-by-element multiplication operation. In this example, the
code may result in a 10.times.10 orthogonal P-matrix based on the
dimensions of the first row and the number of rows specific by the
variable P. Other mathematical operations may be performed on
smaller P-matrices or arrays to produce new matrices with desired
dimensions for storage at the APs 105, the STAs 115, or both. Each
constituent matrix may be an example of an orthogonal DFT matrix or
may contain different characteristic entries to avoid creating
spectral lines or channel interferences.
[0059] The number of high volume matrices--for example, matrices
with dimensions greater than 8.times.8--stored by the AP 105-a may
be limited by an LTF overhead wastage threshold. For example, if
the AP 105-a stores one P-matrix larger than 8.times.8, such as a
16.times.16 matrix, the AP 105-a transmits a full set of sixteen
LTF symbols for any number of space-time-streams greater than eight
streams. In this example, if the AP 105-a transmits using ten
space-time-streams, the AP 105-a may experience an LTF overhead
wastage of six LTFs, as a full set of sixteen LTF symbols is used
for ten space-time-streams in order to support modulation by the
16.times.16 orthogonal matrix. Alternatively, if the AP 105-a
stores a 10.times.10 matrix in addition to the 16.times.16 matrix,
the AP 105-a may use additional memory resources for storing the
additional matrix, but may reduce the LTF overhead wastage by
transmitting ten LTFs when transmitting using ten
space-time-streams. In this way, the AP 105-a may experience a
tradeoff between the number of P-matrices stored in memory and the
LTF overhead wastage, where a greater number of stored P-matrices
results in less LTF overhead wastage but greater memory usage. As
such, in some implementations, AP 105-a may store multiple
P-matrices, including both small P-matrices (that is, P-matrices
with dimensions 8.times.8 or smaller) and large P-matrices (that
is, P-matrices with dimensions larger than 8.times.8). For example,
an AP 105-a may store P-matrices including P.sub.2.times.2,
P.sub.4.times.4, P.sub.6.times.6, P.sub.8.times.8,
P.sub.10.times.10, P.sub.12.times.12, P.sub.14.times.14, and
P.sub.16.times.16.
[0060] In some implementations, an AP 105-a may use a P-matrix for
modulation such that each dimension of the P-matrix is less than
the total number of space-time-streams. For example, rather than
store high volume P-matrices with dimensions greater than
8.times.8, the AP 105-a may use smaller P-matrices, such as an
8.times.8 orthogonal P-matrix, to modulate LTFs for high volume
space-time-stream transmissions. The AP 105-a may modulate the LTF
section 215 over the space-time-streams using the selected P-matrix
and may transmit the modulated LTF 215 over a set of tones
corresponding to the space-time-streams. To handle modulation of
the LTF section 215 with a P-matrix that has dimensions smaller
than the number of space-time-streams, the AP 105-a may use one or
more modulation techniques as described below with reference to
FIGS. 3 and 4.
[0061] FIG. 3 shows an example of techniques for performing LTF
modulation in a wireless communications system 300 that supports
high volumes of space-time-streams. The wireless communications
system 300 may be an example of a Next Generation or EHT Wi-Fi
system, and may include an AP 105-b, a STA 115-b, and a coverage
area 110-b, which may be examples of the corresponding components
described with respect to FIGS. 1 and 2. The AP 105-b may transmit
a packet on the downlink 305 to the STA 115-b using a number of
space-time-streams. The AP 105-b may use a first LTF modulation
technique 310-a, a second LTF modulation technique 310-b, or a
combination thereof to modulate an LTF section of the packet for
transmission. In the first LTF modulation technique 310-a, the AP
105-b may use a first P-matrix 315-a to modulate a first group of
space-time-streams across the LTF symbols over a first set of
frequency tones 320 and may use a second P-matrix 315-b to modulate
a second group of space-time-streams across the LTF symbols over a
second set of frequency tones 320. The first and second sets of
frequency tones 320 may be interleaved. In the second LTF
modulation technique 310-b, the AP 105-b may modulate the
space-time-streams across symbols in the time domain using a first
P-matrix 315-a and may modulate the space-time-streams across
frequency tones 320 in the frequency domain using a third P-matrix
315-c.
[0062] In some implementations, an AP 105-b and a STA 115-b may
utilize a smaller P-matrix 315 for estimating a channel with a
larger number of space-time-streams (for example, an AP 105-b may
modulate an LTF section with sixteen space-time-streams using a
P-matrix 315 with dimensionality less than 16.times.16). In a first
LTF modulation technique 310-a, the AP 105-b may modulate and
transmit different groups of streams on different frequency tones
320. In one implementation, the first LTF modulation technique
310-a may be an example of a tone-interleaving process, where the
AP 105-b may switch between or select certain tones for certain
space-time-streams to support a higher number of space time streams
in a network. The AP 105-b may modulate stream groups using
multiple orthogonal P-matrices 315, such as P-matrix 315-a and
P-matrix 315-b, which in some implementations may be examples of
the same matrix. In the first LTF modulation technique 310-a, AP
105-b may separate the total number of space-time-streams (for
example, sixteen streams) into stream sets each containing a number
of streams less than or equal to the size of the P-matrix 315 for
modulation (for example, a first set of streams 1-8 and second set
of streams 9-16 if P-matrices 315-a and 315-b are at least
8.times.8). The AP 105-b may identify a number of frequency tones
320 for transmission of the packet and may use a tone interleaving
technique to transmit the sixteen streams with less than sixteen
corresponding LTFs (for example, eight LTFs and an 8.times.8
P-matrix may be used for sixteen space-time-streams). In an
example, the AP 105-b modulates streams 1-8 using the P-matrix
315-a over the odd frequency tones 320 and modulates streams 9-16
using the P-matrix 315-b over the even tones and transmits these
subsets of space-time-streams on the alternating frequency tones
320.
[0063] A receiving STA 115-b may receive the packet with the
modulated LTFs, and may use interpolation to determine the channel
for every stream on every frequency tone 320. For example, the STA
115-b may use interpolation or another estimation technique to
estimate the channel for streams 1-8 on the even tones and for
streams 9-16 on the odd tones. In some implementations, the
interpolation process may involve the STA 115-b averaging values
for corresponding alternate tones to determine a value for an
intermediate frequency tone 320. For example, for the first
space-time-stream, the STA 115-b may average two odd frequency
tones 320 to estimate the channel associated with the even
frequency tone 320 between the two odd frequency tones 320.
[0064] In a second LTF modulation technique 310-b, modulating an
LTF section in both time and frequency may provide separation
between space-time-streams on adjacent tones without tone
interleaving. An AP 105-b may apply an orthogonal code over time
resources using a P-matrix 315-a. Additionally, the AP 105-b may
apply an orthogonal code over frequency resources (for example,
frequency tones 320) using a P-matrix 315-c to separate spatial
streams over tone blocks. While P-matrices 315-a and 315-c may each
have smaller dimensions than the number of space-time-streams, in
combination the P-matrices 315 may modulate the larger number of
streams (for example, sixteen streams). P-matrix 315-a and P-matrix
315-c may be the same matrix or may be different matrices. In one
example, the AP 105-b may use a P-matrix 315-a of one size (for
example, an 8.times.8 P-matrix) to modulate across OFDM symbols and
a P-matrix 315-c of another size different than P-matrix 315-a (for
example, a 2.times.2 P-matrix) to modulate across frequency tones
320. That is, the AP 105-b may spread the space-time-streams over
blocks of tones using the P-matrix 315-c to separate the streams
across the full set of frequency resources and may modulate the
space-time-streams across the time resources (for example, the LTF
symbols) using the P-matrix 315-a. The AP 105-b may differentiate a
larger number of streams than the number of LTFs by modulating the
LTFs across both OFDM symbols and across blocks of frequency tones
320 using two P-matrices 315. In some implementations, the product
of the dimensions of the selected P-matrices 315-a and 315-c may be
greater than or equal to the number of space-time-streams, which
may allow for differentiating the full set of space-time-streams
during the second LTF modulation technique 310-b.
[0065] In some implementations, the AP 105-b may utilize LTF
compression techniques in addition to LTF modulation techniques
310. For example, the AP 105-b may use shorter or compressed LTFs
(for example, 1.times. or 2.times.LTFs) in a packet for
transmission. The AP 105-b may transmit these short LTFs across a
smaller number of tones. As compared to transmitting an
uncompressed LTF, the AP 105-b may transmit 2.times.LTFs on one
half the tones of the uncompressed LTF and may transmit
1.times.LTFs on one quarter of the tones of the uncompressed LTF.
In further examples, the AP 105-b may use other sizes of compressed
LTFs in packet transmissions over other specified tones. A STA
115-b receiving a compressed LTF may perform additional
interpolation as compared to a STA 115-b receiving an uncompressed
LTF to estimate the channel across the full set of frequency tones
320. In some implementations, the amount of interpolation performed
by the STA 115-b may increase as the LTF compression factor
increases. In one specific example, the AP 105-b may implement the
first LTF modulation technique 310-a for modulating 2x LTFs using
sixteen space-time-streams across half a set of frequency tones
320, where subsets of the streams are interleaved in this half set
of frequency tones 320. In this example, a receiving STA 115-b may
interpolate to estimate the channel for the interleaved frequency
tones 320 for each space-time-stream based on the first LTF
modulation technique 310-a. Additionally, the receiving STA 115-b
may interpolate to estimate the channel for the other half set of
frequency tones 320 based on the LTF compression.
[0066] In some wireless communications systems 300, a STA 115-b may
transmit a packet with an LTF section on the uplink to the AP
105-b. For example, the STA 115-b may transmit the packet in a
multi-user (MU) multiple-input, multiple-output (MIMO) system. In
some implementations of this uplink MU-MIMO LTF design, the LTF
section may be long (for example, longer than an LTF threshold
length), which may impact the reliability and accuracy of carrier
phase tracking. Phase tracking may occur on a per-STA 115 or per-AP
105 basis. In transmissions involving long LTF sections, a STA
115-b may implement a method involving tone-interleaved LTFs or
other LTF modulation techniques 310 similar to those described
above with respect to downlink 305 transmissions from the AP
105-b.
[0067] In some implementations, the wireless communications system
300 may implement a number of cyclic shift delays (CSDs) for signal
transmission and per-stream orthogonality. CSDs may reduce
correlation and improve diversity between space-time-streams and
may result in improved automatic gain control (AGC) settings at a
receiving device. An AP 105-b may use a CSD table to determine
signal timing, where each table value corresponds to a time
interval T.sub.CS,VHT.sub.(n) (for example, a certain number of
nanoseconds (ns)) that the AP 105-b may delay a transmission for
the corresponding space-time-stream. The AP 105-b may store such a
CSD table in memory and may identify values from the CSD table for
transmissions (for example, physical layer convergence protocol
(PLCP) protocol data unit (PPDU) transmissions) using multiple
spatial streams. The CSD values in the table may be determined such
that the spatial streams are de-coupled and have timing diversity
better than some threshold timing diversity (for example, at least
50 ns). A CSD value may relate to the number of total
space-time-streams present in a system or may be constant for a
given space-time-stream index no matter the number of
space-time-streams in the system. Multiple CSD tables may be
constructed for various numbers of space-time-streams based on
measurements, simulations, optimizations, or other techniques. An
example of a CSD table constructed for transmission of up to eight
total space-time-streams is given below:
TABLE-US-00001 TABLE 1 T.sub.CS, VHT(n) values for the modulated
fields of a PPDU Total number of space- time-streams Cyclic Shift
for space-time-stream n (ns) (N.sub.STS, total) 1 2 3 4 5 6 7 8 1 0
-- -- -- -- -- -- -- 2 0 -400 -- -- -- -- -- -- 3 0 -400 -200 -- --
-- -- -- 4 0 -400 -200 -600 -- -- -- -- 5 0 -400 -200 -600 -350 --
-- -- 6 0 -400 -200 -600 -350 -650 -- -- 7 0 -400 -200 -600 -350
-650 -100 -- 8 0 -400 -200 -600 -350 -650 -100 -750
Table 1 may be an example of a CSD table for a legacy system, with
support for up to eight space-time-streams. Similar tables may
exist for systems supporting a larger number of space-time-streams
(for example, up to sixteen space-time-streams in an EHT system).
In such examples, the CSDs for the first eight streams may be based
on Table 1 or may include values different than those given in
Table 1. In some implementations, a CSD reference table may follow
a nested structure, where for each incremental total number of
space-time-streams, the cyclic shifts for each stream may be the
same as for the previous total number of space-time-streams, with
one additional cyclic shift value for the additional stream.
Additionally, the CSD table may contain alternating large and small
values for the space-time-streams (where "large" and "small" are in
comparison to the other CSD values), which may serve to maintain
cyclic shift separation between adjacent streams.
[0068] One example CSD table supporting sixteen space-time-streams
is given below. This example follows a nested structure, so the
cyclic shift values for the first eight spatial streams are given
by Table 1. Additionally, this example follows steps--or cyclic
shift diversity thresholds--of 50 ns and a maximum cyclic shift
value of 800 ns. The cyclic shift values for the additional streams
may be determined such that the CSDs are a certain threshold away
from the existing stream CSDs and the other additional stream CSDs.
In an example, a new stream cyclic shift value may be an average
calculated from values of other cyclic shift values. The additional
values for the CSD table supporting a high volume of
space-time-streams may be calculated using any averaging or
numerical optimization methods or simulations to maximize
performance of the spatial streams. In a system supporting sixteen
space-time-streams, a nested CSD table may include the following
table entries corresponding to the cyclic shifts for
space-time-streams 9-16:
TABLE-US-00002 TABLE 2 Additional T.sub.CS, VHT(n) values for
Space-Time-Streams 9-16 Space-Time-Stream n 9 10 11 12 13 14 15 16
Cyclic Shift -250 -550 -300 -450 -50 -700 -150 -500 (in ns)
These CSD table values are given as examples. It is to be
understood that many other permutations of the new CSD table
entries are possible and depending on the implementation,
performance benefits may vary.
[0069] Additionally, or alternatively, the AP 105-b and the STA
115-b supporting a high volume of space-time-streams (for example,
up to sixteen streams) may communicate using modified signals as
compared to legacy systems (for example, systems supporting up to
eight space-time-streams). For example, the AP 105-b may allocate
additional bits to the High Efficiency Signal A Field (HE-SIG-A) to
support the additional space-time-streams. The AP 105-b may further
introduce additional rows for a spatial configuration field
encoding for the High Efficiency Signal B Field (HE-SIG-B). In some
implementations, the AP 105-b may maintain support for a lower
number of users in a MU-MIMO system despite the additional
space-time-streams. For example, the AP 105-b may support
transmitting to up to eight users (that is, different STAs 115)
using sixteen spatial streams for MU-MIMO transmissions.
[0070] FIG. 4 shows an example of techniques for transmitting an
NDP in a wireless communications system 400 that supports high
volumes of space-time-streams. The wireless communications system
400 may be an example of a Next Generation or EHT Wi-Fi system, and
may include an AP 105-c, a STA 115-c, and a STA 115-d, which may be
examples of the corresponding devices described with respect to
FIGS. 1-3. The AP 105-c may transmit a null data packet
announcement (NDPA) 405, one or more NDPs 410, and a trigger frame
415. Each STA 115 may transmit a beam forming (BF) report 420. For
example, STA 115-c may transmit BF report 420-a and STA 115-d may
transmit BF report 420-b. The AP 105-c may include a total number
of antennas or antenna ports for transmitting NDPs 410 on
space-time-streams. However, some STAs 115 may not be configured to
receive the number of streams that the AP 105-c is transmitting. To
manage this, the AP 105-c may transmit the one or more NDPs 410
using a first technique 430-a, a second technique 430-b, or a third
technique 430-c. In the first technique 430-a, the AP 105-c may
transmit a first NDP 410-a using a first group of antennas 425-a
and a second NDP 410-b using a second group of antennas 425-b. In
the second technique 430-b, the AP 105-c may transmit a single NDP
410, where the AP 105-c may transmit the single NDP 410 on a first
set of streams in a first set of tones using a first group of
antennas 425-a and on a second set of streams in a second set of
tones using a second group of antennas 425-b. As discussed above,
the antennas may refer to physical antennas or logical antenna
ports. In the third technique 430-c, the AP 105-c may modulate the
NDP 410 across LTF symbols using a first P-matrix 435-a and may
modulate across pairs or groups of adjacent frequency tones using a
second P-matrix 435-b. Each of the first technique 430-a, the
second technique 430-b, and the third technique 430-c may support
STAs 115 that may not process the full number of LTFs or streams in
sounding.
[0071] In some implementations, NDPs 410 may remain unchanged for
systems supporting high volumes of space-time-streams as compared
to systems supporting lower volumes of space-time-streams, such as
eight space-time-streams. In some other implementations, the NDP
410 format may change based on the numbers of space-time-streams
used for transmission. The increased volume of space-time streams
may have implications for other signaling processes, such as the
production of BF reports 420. In some implementations, a BF report
420 may include additional components or additional supported
angles based on the larger number of spatial streams. These new
angles may be used for rotation for other feedback configurations
(for example, for higher dimensioned matrices) and may be sent or
indicated in BF feedback by a STA 115 or AP 105. Additionally, or
alternatively, other fields may be modified due to the high volume
of supported space-time-streams, such as a number of columns (nc)
sub-field, which may include an additional bit to indicate the
larger number of supported streams.
[0072] In the wireless communications system 400, the AP 105-c may
manage a number of STAs 115 with different sounding capabilities.
For example, one set of STAs, including STA 115-c, may not be
configured to process spatial multiplexing with a high volume of
space-time-streams or corresponding LTFs (for example, sixteen
space-time-streams or sixteen LTFs), while another set of STAs 115,
including STA 115-b (which may be an example of an EHT Wi-Fi
device) may support processing the full number of
space-time-streams or LTFs. An AP 105-c may employ a number of
techniques 430 to support communication with STAs 115 capable of
processing up to eight spatial streams while efficiently
communicating with STAs 115 capable of processing up to sixteen
spatial streams. In this way, the AP 105-c may accommodate STAs 115
with lesser sounding capabilities while communicating using
improved spatial multiplexing and spectral efficiency with STAs 115
supporting greater sounding capabilities.
[0073] In a first technique 430-a, the AP 105-c may contain a set
of antennas--that is, physical antennas or logical antenna
ports--to transmit information to a STA 115-c. The AP 105-c may
perform a sounding process to transmit a sequence of NDPs 410-a and
410-b, where each NDP 410 contains a number of LTFs within the
sounding capability of the STA 115-c. During the sounding process,
the AP 105-c may sound a first group of antennas 425-a of the total
set of antennas to transmit the first NDP 410-a in a first attempt
and may sound a second group of antennas 425-b of the total set of
antennas to transmit a second NDP 410-b in a second attempt. This
first group of antennas 425-a and second group of antennas 425-b
may overlap (for example, share at least one same antenna between
the two groups) or may be mutually exclusive. For example, if the
AP 105-c utilizes sixteen space-time-streams (and, corresponding,
sixteen LTFs), and the STA 115-c is capable of processing eight
space-time-streams or LTFs, the AP 105-c may transmit two NDPs 410
each containing eight of the sixteen LTFs. In such implementations,
the receiving STA 115-c may stitch the two channel components
together to determine the sixteen LTFs. In some implementations,
the different groups of antennas 425-a and 425-b may have different
automatic gain control (AGC) states as processed by STA 115-c, for
example, due to transmitting the NDPs 410 in different attempts.
The STA 115-c may calibrate out or otherwise mitigate any
differences in the AGC states in order to stitch the channel
components. Additionally, or alternatively, the AP 105-c may freeze
the phase for transmission of the different NDPs 410 to remove or
mitigate any phase offset across the groups of antennas 425
transmitting the NDPs 410 at different times. This also may improve
reception and stitching of the two channel components at the
receiving STA 115-c.
[0074] In a second technique 430-b, the AP 105-c may perform
tone-interleaving using a single NDP 410 over different sets of
tones to support sounding a higher number of streams than the
number of LTFs (for example, sixteen streams with eight LTFs). The
AP 105-c may modulate a transmission using an orthogonal P-matrix
or multiple P-matrices. The AP 105-c may transmit the NDP 410 on a
first set of tones using a first subset of antennas 425-a and may
further transmit the NDP 410 on a second set of tones using a
second subset of antennas 425-b. In some implementations, the first
and second set of tones may be half of the total number of tones
used for transmission and may be interleaved in the frequency
domain. In some implementations, the first subset of antennas 425-a
and the second subset of antennas 425-b may contain one or more
shared antennas for improved reception and stitching at the
receiving STA 115-c. For example, antennas shared between the first
and second subsets of antennas 425 may serve as phase references
for the receiving STA 115-c.
[0075] In a third technique 430-c, the AP 105-c may use an
orthogonal code (for example, an orthogonal cover code (OCC) or
some other orthogonal code, such as a P-matrix) for frequency
domain modulation in addition to an orthogonal P-matrix 435-a used
for time domain modulation. In one implementation, the AP 105-c may
use one P-matrix 435-a of one size (for example, an 8.times.8
P-matrix) for modulation across LTF symbols in the time domain and
may use a second P-matrix 435-b of another size (for example, a
2.times.2 P-matrix) for modulation across adjacent tones in the
frequency domain. This may allow a STA 115-c capable of receiving 8
space-time-streams or LTFs to differentiate sixteen
space-time-streams.
[0076] FIG. 5 shows an example of space-time-stream and super
stream transmissions in a wireless communications system 500 that
supports managing high volumes of space-time-streams. The wireless
communications system 500 may be an example of a Next Generation or
EHT Wi-Fi system, and may include an AP 105-d and a STA 115-e,
which may be examples of the devices described with respect to
FIGS. 1-4. The AP 105-d may transmit one or more packets (such as
an NDP) to the STA 115-e in space-time-streams 505. The AP 105-d
may combine some space-time-streams 505 to form super streams 510.
If the STA 115-e is configured for a high volume of streams (for
example, greater than eight streams), the STA 115-e may detect and
receive all of the space-time-streams 505. If the STA 115-e is not
configured for a high volume of streams, the STA 115-e may detect
the super streams 510 as if they are space-time-streams 505, so
that, as illustrated, the STA 115-e may detect and receive eight
space-time-streams 505, rather than the full ten transmitted
space-time-streams 505.
[0077] The AP 105-d may transmit a high volume of
space-time-streams (for example, greater than eight
space-time-streams) in a wireless communications system 500
containing STAs 115 that are not equipped to support a high volume
of streams based on one or more capabilities of the STAs 115. In
some implementations, the AP 105-d may transmit a high volume of
streams by implementing super-streaming techniques, which may group
or combine a number of space-time-streams 505 into super streams
510 to accommodate the legacy STAs 115 capable of receiving up to a
threshold number of streams (for example, eight space-time-streams)
while still transmitting with more streams than the threshold
number of streams. In some other implementations, super-streaming
techniques may include reducing the number of LTFs corresponding to
a high volume of space time streams. If a STA 115-e is configured
to support a high volume of streams, the STA 115-e may detect and
receive each of the multiple space-time-streams 505 within super
stream 510 separately, or as individual streams. In some other
implementations, where the STA 115-e is unable to support a high
volume of streams, the STA 115-e may detect and receive a super
stream 510 as a single space-time-stream 505. In some
implementations, an AP 105-d transmitting, for example, sixteen
space-time-streams 505 may transmit eight super streams 510, where
each super stream 510 contains two single space-time-streams 505.
This may result in some STAs 115 receiving sixteen streams for a
single transmission while other STAs receive a different number of
streams due to the different capabilities of the STAs 115. In some
other implementations, an AP 105-d may transmit ten
space-time-streams 505 including two super streams 510, where each
super stream 510 contains two of the space-time-streams 505. This
may result in a subset of the STAs 115 in the wireless
communications system 500 detecting ten streams (the ten
space-time-streams 505) while a different subset of STAs 115 may
detect eight streams (the two super streams 510 and the six
uncombined space-time-streams 505).
[0078] In some implementations, STAs 115 and APs 105 may implement
super streams 510 in uplink and downlink transmissions, such as
MU-MIMO LTF transmissions. In some implementations, an AP 105 may
transmit a packet in a downlink MU-MIMO system to a STA 115, which
may not be configured to support a high volume of space-time
streams. In one implementation, some STAs 115 served by an AP 105
may support up to sixteen total space time streams, while another
STA 115 served by AP 105 may support reception of eight total space
time streams. In order to transmit for example, twelve space time
streams in a downlink MU-MIMO transmission, AP 105 may transmit
four singular space time streams along with four super streams each
consisting of two singular space-time streams. In this example,
STAs 115 supporting a high volume of space time streams may receive
the transmission as containing twelve total space time streams,
while the STA 115 with lesser reception capabilities may receive
the transmission as containing eight total space time streams.
[0079] The STAs 115 may use a P-matrix for LTF modulation and
transmission across tones. The AP 105-d may allocate a row of the
P-matrix (e.g., a channel estimation resource) to a STA 115-e,
where the STA 115-e is configured for a lower volume of streams.
For STAs 115 supporting a higher volume of streams, the AP 105-d
may allocate some rows of the P-matrix such that the rows shift
during modulation between different streams across tones. For
example, an EHT STA 115 may rotate a row of the P-matrix between
space-time-streams from tone-to-tone, generating two streams from a
single row of the P-matrix. The AP 105-d receiving the two streams
may perform interpolation to estimate the channel for the
in-between tones. For example, if the EHT STA 115 modulates streams
1-6 on a first tone and streams 7-12 on a second tone, the AP 105-d
may interpolate LTF values for streams 7-12 on the first tone and
interpolate LTF values for streams 1-6 on the second tone. In
another example, APs 105-d may share the same row of the
P-matrix.
[0080] FIG. 6 shows a block diagram of an example system 600
including an AP 605 that supports high volumes of
space-time-streams. The AP 605 may be an example of a wireless
device configured to operate in a Next Generation or EHT Wi-Fi
system. The AP 605 may include components for bi-directional voice
and data communications including components for transmitting and
receiving communications, such as a processor 620, a memory 625,
software 630, a transceiver 635, an antenna 640, and an
input/output (I/O) controller 645. These components may be in
electronic communication via one or more buses, such as a bus 610.
The transceiver 635 may include a space-time-stream packet module
615 configured to implement one or more of the techniques described
with respect to FIGS. 1-5, in cooperation with the processor 620, a
memory 625, software 630, antenna 640, and I/O controller 645.
[0081] The space-time-stream packet module 615 may perform a number
of operations for managing high volumes of space-time-streams. For
example, the space-time-stream packet module 615 may handle
transmitting packets to different types of STAs 115, where some
STAs 115 in the system 600 are capable of processing up to eight
space-time-streams and other STAs 115 in the system 600 are capable
of processing more than eight space-time-streams. For example, the
first type of STAs 115 may be referred to as "legacy" STAs, and the
second type of STAs 115 may be referred to as "EHT" STAs and may
process up to sixteen space-time-streams (i.e., a "high volume" of
space-time-streams). In some implementations, in addition or
alternative to having a limit on space-time-stream processing
capabilities, a STA 115 may have similar limits on processing LTFs
in sounding. For example, legacy STAs may support processing up to
eight LTFs in sounding, while EHT STAs may support processing up to
sixteen LTFs in sounding.
[0082] In a first example, the space-time-stream packet module 615
may identify a number of space-time-streams for transmission of NDP
information in a set of tones, where the number of
space-time-streams is greater than a threshold number of streams.
This threshold number of streams may be based on the different
capabilities of STAs 115 in the system 600. For example, the
threshold number of streams may be equal to eight streams, where a
subset of the STAs 115 support processing more than the threshold
number of streams and another subset of STAs 115 support processing
less than or equal to the threshold number of streams. The
space-time-stream packet module 615, via the transceiver 635 and
antennas 640, may transmit a first subset of the NDP information
using a first subset of the antennas 640, such as half of the
antennas 640, and may transmit a second subset of the NDP
information using a second subset of the antennas 640, such as the
other half of the antennas 640.
[0083] In a second example, the space-time-stream packet module 615
may identify the number of space-time-streams for transmission of a
packet, where the number of space-time-streams is greater than the
threshold number of streams. This packet may include an LTF section
spanning one or more OFDM symbols. The space-time-stream packet
module 615 may select an orthogonal matrix for modulation of the
LTF section. In some implementations, the orthogonal matrix may be
selected from a lookup table in the memory 625. A size of the first
dimension and the second dimension of the matrix may be less than
the identified number of space-time-streams. The space-time-stream
packet module 615 may modulate the LTF section over the
space-time-streams using the selected orthogonal matrix--that is,
the space-time-stream packet module 615 may spread the
space-time-streams over the OFDM symbols of the LTF section using
the selected orthogonal matrix. The space-time-stream packet module
615 may use tone-interleaving with interpolation or separate
matrices in time and frequency to fully spread the signal using a
matrix with dimensions smaller than the number of
space-time-streams. The space-time-stream packet module 615, via
the transceiver 635 and antenna(s) 640, may transmit the packet
including the modulated LTF section over a set of tones using the
space-time-streams.
[0084] In a third example, the space-time-stream packet module 615
may identify the number of space-time-streams for transmission of a
packet, where the number of space-time-streams is greater than the
threshold number of streams. The space-time-stream packet module
615 may combine some of the space-time-streams to form one or more
super streams and obtain a total number of streams equal to or less
than the threshold number of streams. For example, if the
space-time-stream packet module 615 identifies ten streams, but the
threshold number of streams is eight, the space-time-stream packet
module 615 may form two super streams composed of two
space-time-streams each. The space-time-stream packet module 615,
via the transceiver 635 and antenna(s) 640, may transmit the packet
over a set of tones using the super streams and space-time-streams.
Legacy STAs 115 may receive each super stream as a single
space-time-stream, while EHT STAs 115 may receive each super stream
as its component space-time-streams. Accordingly, in the example
given above, a legacy STA 115 may identify eight streams while an
EHT STA 115 may identify ten streams for the same transmission
based on these super streams.
[0085] In a fourth example, the space-time-stream packet module 615
may identify the number of space-time-streams for transmission of
NDP information in a set of tones. This NDP information may include
an LTF section spanning one or more OFDM symbols. The
space-time-stream packet module 615 may determine that the number
of space-time-streams is greater than the threshold number of
space-time-streams and may group the set of tones into tone blocks.
The space-time-stream packet module 615 may modulate an NDP
containing the NDP information across the OFDM symbols of the LTF
section using a first orthogonal matrix and across each of the tone
blocks using a second orthogonal matrix. In some implementations,
these matrices may be selected from a lookup table in the memory
625. The space-time-stream packet module 615, via the transceiver
635 and antenna(s) 640, may transmit the modulated NDP over the set
of tones using the space-time-streams. The space-time-stream packet
module 615 may operate as described above in a single example, or
in any combination of the examples.
[0086] The processor 620 may include an intelligent hardware
device, such as a general-purpose processor, a digital signal
processor (DSP), a central processing unit (CPU), a
microcontroller, an application-specific integrated circuit (ASIC),
a field-programmable gate array (FPGA), a programmable logic
device, a discrete gate or transistor logic component, a discrete
hardware component, or some combination of these components. The
processor 620 may be configured to execute computer-readable
instructions stored in a memory to perform various functions, such
as the functions described with respect to the space-time-stream
packet module 615.
[0087] The memory 625 may include random access memory (RAM) and
read-only memory (ROM). The memory 625 may store computer-readable,
computer-executable code or software 630 including instructions
that, when executed, cause the processor to perform various
functions described herein. In some implementations, the memory 625
may contain, among other things, a basic input/output system (BIOS)
which may control basic hardware or software operation such as the
interaction with peripheral components or devices.
[0088] The transceiver 635 may communicate bi-directionally, via
one or more antennas 640 or antenna ports, wired, or wireless links
as described above. For example, the transceiver 635 may represent
a wireless transceiver and may communicate bi-directionally with
another wireless transceiver. The transceiver 635 also may include
a modem to modulate the packets and provide the modulated packets
to the antennas 640 for transmission, and to demodulate packets
received from the antennas 640. The antennas 640 may transmit
packets, such as NDPs, to STAs 115 or other APs 105 within the
system 600.
[0089] The I/O controller 645 may manage input and output signals
for the AP 605. The I/O controller 645 also may manage peripherals
not integrated into the AP 605. In some implementations, the I/O
controller 645 may represent a physical connection or port to an
external peripheral. In some other implementations, the I/O
controller 645 may be implemented as part of a processor 620. A
user may interact with the AP 605 via the I/O controller 645 or via
hardware components controlled by the I/O controller 645.
[0090] The AP 605 may include alternative or additional components
to those described above. For example, the AP 605 may include a
network communications manager, an inter-station communications
manager, or any combination of these or any other AP 605
components.
[0091] FIG. 7 shows a flowchart illustrating an example method 700
for managing high volumes of space-time-streams in Next Generation
Wi-Fi systems. The operations of the method 700 may be implemented
by an AP 105 or its components as described herein. For example,
the operations of method 700 may be implemented by a
space-time-stream packet module 615 as described with reference to
FIG. 6.
[0092] At block 705 the AP 105 may identify a number of
space-time-streams for transmission of a packet, the packet
including an LTF section that contains one or more OFDM symbols. At
block 710 the AP 105 may select an orthogonal matrix for modulation
of the LTF section, where a size of a first and a second dimension
of the orthogonal matrix is less than the number of
space-time-streams. In some implementations, the size of the matrix
may be based on a number of LTF indices, on a number of
space-time-streams, or on a maximum supported matrix size. For
example, the matrix may be an example of an 8.times.8 orthogonal
matrix stored in the memory of the AP 105. At block 715 the AP 105
may modulate the LTF section over the space-time-streams using the
selected orthogonal matrix. For example, the AP 105, using a
modulator, may spread the space-time-streams over the OFDM symbols
of the LTF section using the selected orthogonal matrix. In some
implementations, the AP 105 may additionally perform interpolation
or frequency spreading to fully modulate the LTF section. At block
720 the AP 105 may transmit, via one or more antennas and using a
transmitter or transceiver, the packet including the modulated LTF
section over a set of tones using the space-time-streams.
[0093] FIG. 8 shows a flowchart illustrating an example method 800
for managing high volumes of space-time-streams in Next Generation
Wi-Fi systems. The operations of the method 800 may be implemented
by an AP 105 or its components as described herein. For example,
the operations of the method 800 may be implemented by a
space-time-stream packet module 615 as described with reference to
FIG. 6.
[0094] At block 805 the AP 105 may identify a number of
space-time-streams for transmission of NDP information in a set of
tones, the NDP information including an LTF section that contains
OFDM symbols. At block 810 the AP 105 may determine that the number
of space-time-streams is greater than a threshold number of
streams. In some implementations, the determination may be
implicit, and may be based on the system in which the AP 105
operates. For example, if the AP 105 operates within a system
supporting both legacy and EHT STAs 115--that is, STAs 115 that
support processing for different numbers of space-time-streams,
LTFs, or both--the AP 105 may implicitly perform the following
functions. At block 815 the AP 105 may transmit, using a
transmitter or transceiver, a first subset of the NDP information
corresponding to a first subset of antennas, where a number of the
first subset of antennas is less than or equal to the threshold
number of streams. At block 820 the AP 105 may transmit, using the
transmitter or transceiver, a second subset of the NDP information
corresponding to a second subset of the antennas, where a number of
the second subset of antennas is less than or equal to the
threshold number of streams.
[0095] FIG. 9 shows a flowchart illustrating an example method 900
for managing high volumes of space-time-streams in Next Generation
Wi-Fi systems. The operations of the method 900 may be implemented
by an AP 105 or its components as described herein. For example,
the operations of the method 900 may be may be implemented by a
space-time-stream packet module 615 as described with reference to
FIG. 6.
[0096] At block 905 the AP 105 may identify a number of
space-time-streams for transmission of NDP information in a set of
tones, the NDP information including an LTF section that contains
one or more OFDM symbols. At block 910 the AP 105 may determine
(implicitly or explicitly) that the number of the
space-time-streams is greater than a threshold number of streams.
The threshold number of streams may be based on the capabilities of
STAs 115 in the system. At block 915 the AP 105 may group the set
of tones into a number of tone blocks. At block 920 the AP 105 may
modulate an NDP including the NDP information across the one or
more OFDM symbols of the LTF section using a first orthogonal
matrix and across each of the number of tone blocks using a second
orthogonal matrix. These orthogonal matrices may be stored in the
memory of the AP 105. In one example, the first orthogonal matrix
is an 8.times.8 orthogonal matrix and the second orthogonal matrix
is a 2.times.2 orthogonal matrix. At block 925 the AP 105 may
transmit the modulated NDP over the set of tones using the number
of space-time-streams. The AP 105 may perform this transmission
using a transmitter or transceiver and one or more antennas or
antenna ports.
[0097] FIG. 10 shows a flowchart illustrating an example method
1000 for managing high volumes of space-time-streams in Next
Generation Wi-Fi systems. The operations of the method 1000 may be
implemented by an AP 105 or its components as described herein. For
example, the operations of the method 1000 may be implemented by a
space-time-stream packet module 615 as described with reference to
FIG. 6.
[0098] At block 1005 the AP 105 may identify a number of
space-time-streams for transmission of a packet. At block 1010 the
AP 105 may determine (implicitly or explicitly) that the number of
the space-time-streams is greater than a threshold number of
space-time-streams. In some implementations, this determination may
be based on the capabilities of different STAs 115 serviced by the
AP 105. At block 1015 the AP 105 may combine a number of the
space-time-streams to form one or more super streams, where a total
number of the one or more super streams and any remaining
uncombined space-time-streams is less than or equal to the
threshold number of streams. For example, if the AP 105 determines
to transmit the packet using sixteen space-time-streams, but a
subset of the STAs 115 (legacy STAs) receiving the
space-time-streams support up to eight space-time-streams, the AP
105 may instead transmit the packet using eight super streams,
where each super stream contains two space-time-streams. At block
1020 the AP 105 may transmit the packet over a set of tones using
the one or more super streams and the remaining uncombined
space-time-streams. For example, the AP 105 may transmit the super
streams and space-time-streams using a transmitter or transceiver
and any number of antennas or antenna ports. A legacy STA 115
supporting eight streams receiving the packet may identify eight
streams (for example, the eight super streams), while an EHT STA
115 supporting sixteen streams receiving the packet may identify
sixteen streams (for example, the sixteen space-time-streams making
up the super streams).
[0099] As used herein, a phrase referring to "at least one of" a
list of items refers to any combination of those items, including
single members. As an example, "at least one of: a, b, or c" is
intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c.
[0100] The various illustrative logics, logical blocks, modules,
circuits and algorithm processes described in connection with the
implementations disclosed herein may be implemented as electronic
hardware, computer software, or combinations of both. The
interchangeability of hardware and software has been described
generally, in terms of functionality, and illustrated in the
various illustrative components, blocks, modules, circuits and
processes described above. Whether such functionality is
implemented in hardware or software depends upon the particular
application and design constraints imposed on the overall
system.
[0101] The hardware and data processing apparatus used to implement
the various illustrative logics, logical blocks, modules and
circuits described in connection with the aspects disclosed herein
may be implemented or performed with a general purpose single- or
multi-chip processor, a DSP, an ASIC, an FPGA or other programmable
logic device, discrete gate or transistor logic, discrete hardware
components, or any combination thereof designed to perform the
functions described herein. A general-purpose processor may be a
microprocessor, or, any conventional processor, controller,
microcontroller, or state machine. A processor also may be
implemented as a combination of computing devices, such as a
combination of a DSP and a microprocessor, a number of
microprocessors, one or more microprocessors in conjunction with a
DSP core, or any other such configuration. In some implementations,
particular processes and methods may be performed by circuitry that
is specific to a given function.
[0102] In one or more aspects, the functions described may be
implemented in hardware, digital electronic circuitry, computer
software, firmware, including the structures disclosed in this
specification and their structural equivalents thereof, or in any
combination thereof. Implementations of the subject matter
described in this specification also can be implemented as one or
more computer programs, i.e., one or more modules of computer
program instructions, encoded on a computer storage media for
execution by, or to control the operation of, data processing
apparatus.
[0103] If implemented in software, the functions may be stored on
or transmitted over as one or more instructions or code on a
computer-readable medium. The processes of a method or algorithm
disclosed herein may be implemented in a processor-executable
software module which may reside on a computer-readable medium.
Computer-readable media includes both computer storage media and
communication media including any medium that can be enabled to
transfer a computer program from one place to another. A storage
media may be any available media that may be accessed by a
computer. By way of example, and not limitation, such
computer-readable media may include RAM, ROM, electrically erasable
programmable ROM (EEPROM), compact disc ROM (CD-ROM) or other
optical disk storage, magnetic disk storage or other magnetic
storage devices, or any other medium that may be used to store
desired program code in the form of instructions or data structures
and that may be accessed by a computer. Also, any connection can be
properly termed a computer-readable medium. Disk and disc, as used
herein, includes compact disc (CD), laser disc, optical disc,
digital versatile disc (DVD), floppy disk, and Blu-ray disc where
disks usually reproduce data magnetically, while discs reproduce
data optically with lasers. Combinations of the above also may be
included within the scope of computer-readable media. Additionally,
the operations of a method or algorithm may reside as one or any
combination or set of codes and instructions on a machine readable
medium and computer-readable medium, which may be incorporated into
a computer program product.
[0104] Various modifications to the implementations described in
this disclosure may be readily apparent to those skilled in the
art, and the generic principles defined herein may be applied to
other implementations without departing from the spirit or scope of
this disclosure. Thus, the claims are not intended to be limited to
the implementations shown herein, but are to be accorded the widest
scope consistent with this disclosure, the principles and the novel
features disclosed herein.
[0105] Additionally, a person having ordinary skill in the art will
readily appreciate, the terms "upper" and "lower" are sometimes
used for ease of describing the figures, and indicate relative
positions corresponding to the orientation of the figure on a
properly oriented page, and may not reflect the proper orientation
of any device as implemented.
[0106] Certain features that are described in this specification in
the context of separate implementations also can be implemented in
combination in a single implementation. Conversely, various
features that are described in the context of a single
implementation also can be implemented in multiple implementations
separately or in any suitable subcombination. Moreover, although
features may be described above as acting in certain combinations
and even initially claimed as such, one or more features from a
claimed combination can in some implementations be excised from the
combination, and the claimed combination may be directed to a
subcombination or variation of a subcombination.
[0107] Similarly, while operations are depicted in the drawings in
a particular order, this may not be understood as requiring that
such operations be performed in the particular order shown or in
sequential order, or that all illustrated operations be performed,
to achieve desirable results. Further, the drawings may
schematically depict one more example processes in the form of a
flow diagram. However, other operations that are not depicted can
be incorporated in the example processes that are schematically
illustrated. For example, one or more additional operations can be
performed before, after, simultaneously, or between any of the
illustrated operations. In certain circumstances, multitasking and
parallel processing may be advantageous. Moreover, the separation
of various system components in the implementations described above
may not be understood as requiring such separation in all
implementations, and it may be understood that the described
program components and systems can generally be integrated together
in a single software product or packaged into multiple software
products. Additionally, other implementations are within the scope
of the following claims. In some implementations, the actions
recited in the claims can be performed in a different order and
still achieve desirable results.
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