U.S. patent application number 15/644481 was filed with the patent office on 2018-01-11 for triggered wireless access protocol with grouped multi-user transmissions.
The applicant listed for this patent is Apple Inc.. Invention is credited to Yoel BOGER, Yaniv DVORY, Christiaan A. HARTMAN, Jarkko L. KNECKT, Hay LEV, Guoqing LI, Syed A. MUJTABA, Matthew L. SEMERSKY, Oren SHANI.
Application Number | 20180014165 15/644481 |
Document ID | / |
Family ID | 60911324 |
Filed Date | 2018-01-11 |
United States Patent
Application |
20180014165 |
Kind Code |
A1 |
LI; Guoqing ; et
al. |
January 11, 2018 |
TRIGGERED WIRELESS ACCESS PROTOCOL WITH GROUPED MULTI-USER
TRANSMISSIONS
Abstract
An access point transmits a trigger frame to a set of electronic
devices in a wireless local area network (WLAN). In response to one
or more requests to send data, the access point transmits the
trigger frame, which includes information specifying an ordered
list of electronic devices in the set of electronic devices that
are allowed to transmit, and that groups the electronic devices in
the ordered list of electronic devices into a first subset of the
electronic devices and a second subset of the electronic devices.
Subsequently, the access point sequentially receives one or more
frames from the ordered list of electronic devices, where a first
group of the frames received from at least some of the first subset
of the electronic devices use single-user transmission and a second
group of frames received from at least some of the second subset of
the electronic devices use multi-user transmission.
Inventors: |
LI; Guoqing; (Campbell,
CA) ; SHANI; Oren; (Saratoga, CA) ; HARTMAN;
Christiaan A.; (San Jose, CA) ; KNECKT; Jarkko
L.; (Los Gatos, CA) ; MUJTABA; Syed A.; (Santa
Clara, CA) ; SEMERSKY; Matthew L.; (San Jose, CA)
; DVORY; Yaniv; (Kfar Saba, IL) ; LEV; Hay;
(Modi'in, IL) ; BOGER; Yoel; (Shoham, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Apple Inc. |
Cupertino |
CA |
US |
|
|
Family ID: |
60911324 |
Appl. No.: |
15/644481 |
Filed: |
July 7, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62359941 |
Jul 8, 2016 |
|
|
|
62359940 |
Jul 8, 2016 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 74/06 20130101;
H04L 5/0051 20130101; H04W 72/0446 20130101; H04L 5/0007 20130101;
H04W 84/12 20130101; H04W 88/02 20130101; H04W 4/08 20130101; H04W
74/04 20130101; H04W 88/08 20130101; H04L 5/0048 20130101; H04W
74/006 20130101 |
International
Class: |
H04W 4/08 20090101
H04W004/08; H04L 5/00 20060101 H04L005/00 |
Claims
1. An access point, comprising: one or more nodes configured to
communicatively couple to an antenna; and an interface circuit,
communicatively coupled to the one or more nodes, configured to
communicate with a set of electronic devices in a wireless local
area network (WLAN), and configured to cause the access point to:
transmit, to the set of electronic devices, a trigger frame that
includes information specifying an ordered list of electronic
devices in the set of electronic devices that are allowed to
transmit, and that groups the electronic devices in the ordered
list of electronic devices into a first subset of the electronic
devices and a second subset of the electronic devices; and receive
a sequence of frames from the ordered list of electronic devices,
wherein a first group of frames in the sequence of frames received
from one or more electronic devices of the first subset of the
electronic devices use single-user transmission and a second group
of frames in the sequence of frames received from one or more
electronic devices of the second subset of the electronic devices
use multi-user transmission.
2. The access point of claim 1, wherein lengths and/or data rates
of two or more frames of the sequence of frames received from the
first subset of the electronic devices differ from each other.
3. The access point of claim 1, wherein: the trigger frame
specifies a maximum frame duration, and the frames of the sequence
of frames have durations that are less than or equal to the maximum
frame duration.
4. The access point of claim 1, wherein: the trigger frame
comprises a media access control (MAC) header and a field following
the MAC header that includes the information specifying the ordered
list of electronic devices.
5. The access point of claim 1, wherein the information specifies
explicit triggering; and wherein the interface circuit is further
configured to cause the access point to: transmit an additional
trigger frame to one or more electronic devices in the ordered list
of electronic devices; and receive a frame in the first group of
frames or in the second group of frames in response to the
additional trigger frame.
6. The access point of claim 1, wherein the interface circuit is
further configured to cause the access point to receive from an
electronic device an indication of whether the electronic device
allows for multi-user transmission and to group the electronic
device with the first subset of the electronic devices when
multi-user transmission is not allowed and with the second subset
of the electronic devices when multi-user transmission is
allowed.
7. The access point of claim 6, wherein the indication of whether
the electronic device allows for multi-user transmission applies to
a specific target wake time (TWT) and is communicated to the access
point when negotiating the TWT with the electronic device.
8. The access point of claim 7, wherein the indication is included
in a TWT request frame received from the electronic device.
9. The access point of claim 6, wherein the indication of whether
the electronic device allows for multi-user transmission is
communicated to the access point when associating with the
electronic device and applies subsequent communications while
associated with the electronic device.
10. The access point of claim 1, wherein: the information specifies
an allocation of resource units to the second subset of the
electronic devices; and the second group of frames include data
from one or more electronic devices of the second subset of the
electronic devices using different radio frequency channels.
11. The access point of claim 1, wherein the second group of frames
use Orthogonal Frequency Division Multiple Access (OFDMA).
12. The access point of claim 11, wherein the trigger frame
specifies OFDMA allocation parameters for the second subset of the
electronic devices.
13. An electronic device, comprising: one or more nodes configured
to communicatively couple to an antenna; and an interface circuit,
communicatively coupled to the one or more nodes, configured to
communicate with an access point in a wireless local area network
(WLAN), and configured to cause the electronic device to: receive,
from the access point, a trigger frame that includes information
specifying an ordered list of electronic devices in a set of
electronic devices that are allowed to transmit, the information
including an identifier of the electronic device and an indication
of an assignment of the electronic device to a first subset of the
electronic devices or to a second subset of the electronic devices;
and transmit at least a portion of a frame to the access point,
wherein: when the electronic device is assigned to the first subset
of the electronic devices, the frame is transmitted at a temporal
position in a sequence of one or more frames from the first subset
of the electronic devices using single-user transmission; and when
the electronic device is assigned to the second subset of the
electronic devices, at least the portion of the frame is
transmitted using multi-user transmission.
14. The electronic device of claim 13, wherein the information
specifies a maximum frame duration; and wherein the interface
circuit is further configured to cause the electronic device to
select an amount of data to include in the frame and a data rate
such that the frame has a duration that is less than or equal to
the maximum frame duration.
15. The electronic device of claim 13, wherein the information
specifies explicit triggering; and wherein the interface circuit is
further configured to cause the electronic device to receive an
additional trigger frame from the access point, and to transmit the
frame in response to receipt of the additional trigger frame.
16. The electronic device of claim 13, wherein the information
specifies that each of the electronic devices in the ordered list
of electronic devices responds to the trigger frame; and wherein
the interface circuit is further configured to cause the electronic
device to transmit a null frame when there is no queued data.
17. The electronic device of claim 13, wherein the interface
circuit is further configured to cause the electronic device to
transmit the frame after another frame is transmitted by at least a
preceding electronic device in the ordered list of electronic
devices or during a time slot after an unused transmit opportunity
of at least the preceding electronic device.
18. The electronic device of claim 13, wherein the interface
circuit is further configured to cause the electronic device to
transmit an indication of whether the electronic device allows for
multi-user transmission and the electronic device is grouped by the
access point with the first subset of the electronic devices when
multi-user transmission is not allowed and with the second subset
of the electronic devices when multi-user transmission is
allowed.
19. The electronic device of claim 13, wherein: the information
specifies an allocation of resource units to the second subset of
the electronic devices; the frame includes data from the electronic
device and from one or more other electronic devices in the second
subset of the electronic devices using different frequency
channels.
20. A method for transmitting a frame, comprising: at an interface
circuit in an electronic device: receiving, from an access point, a
trigger frame that includes information specifying an ordered list
of electronic devices in a set of electronic devices that are
allowed to transmit, the information including an identifier of the
electronic device and an indication of an assignment of the
electronic device to a first subset of the electronic devices or to
a second subset of the electronic devices; and transmitting at
least a portion of a frame to the access point, wherein: when the
electronic device is assigned to the first subset of the electronic
devices the frame is transmitted at a temporal position in a
sequence of one or more frames from the first subset of the
electronic devices using single-user transmission; and when the
electronic device is assigned to the second subset of the
electronic devices, at least the portion of the frame is
transmitted using multi-user transmission.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 62/359,940, entitled "TRIGGERED WIRELESS
ACCESS PROTOCOL" filed Jul. 8, 2016, and the benefit of U.S.
Provisional Patent Application No. 62/359,941, entitled "TRIGGERED
WIRELESS ACCESS PROTOCOL" filed Jul. 8, 2016, the contents of both
of which are incorporated by reference herein in their entireties
for all purposes.
FIELD
[0002] The described embodiments relate, generally, to wireless
communications among electronic devices in a wireless local area
network (WLAN), including electronic devices and access points, and
techniques for controlling channel access by transmitting one or
more trigger frames from an access point to the electronic devices
with options for grouped multi-user transmissions from the
electronic devices to the access point.
BACKGROUND
[0003] Many wireless local area networks (WLANs), such as those
based on a communication protocol that is compatible with an
Institute of Electrical and Electronics Engineers (IEEE) 802.11
standard, also referred to as Wi-Fi, involve contention-based
distributed access systems. For example, Wi-Fi often uses
single-user transmission via enhanced distributed channel access
(EDCA). Usually, the WLANs are contention based because they
typically utilize unlicensed frequency bands or spectra, which are
unpredictable and are often subject to interference. The
unpredictability of the interference can make coordination across
multiple electronic devices, also referred to as stations (STAs),
challenging (especially for an unmanaged WLAN), and can result in
failure of a collision free period (CFP). The use of fully
distributed channel access, however, can allow for a low complexity
access point (AP) and simpler network deployment (relative to a
cellular network) of a WLAN.
[0004] Contention-free multi-user transmission in uplink has been
proposed for inclusion in the IEEE 802.11ax standard. This approach
can dramatically change how an electronic device accesses the
communication medium. In particular, an electronic device can
transmit without contending for the communication medium. Instead,
an access point controls access to the communication medium for the
electronic device by granting transmission opportunities to the
electronic device using a trigger frame (also referred to as
`trigger-based access` or `trigger-based channel access,` e.g.,
uplink multi-user transmission). Using trigger-based uplink channel
access, an access point senses the communication medium and, as
needed, performs a backoff process on behalf of potential uplink
trigger-access-enabled electronic devices. Then, the access point
sends a trigger frame with multi-user allocation information to the
electronic devices. In response to the trigger frame, the
electronic devices send uplink traffic on allocated-resource units
in a synchronized manner in a multi-user transmission.
[0005] In principle, the use of trigger-based access and multi-user
transmission can significantly reduce contention for access to the
communication medium by the electronic devices in the WLAN.
Consequently, trigger-based access is expected to result in
improved communication performance.
[0006] Trigger-based access and multi-user transmission, however,
can significantly increase energy consumption of the electronic
devices in the WLAN. In particular, for N electronic devices
sharing a channel, the average data bandwidth may be reduced by a
factor of N and, therefore, the energy required to transmit the
data may be increased by a factor of N. Moreover, the access
overhead in the WLAN typically increases with trigger-based access
and multi-user transmission. Furthermore, this approach for
allocating shared resources can be inefficient (including wasted or
unused resource units and, more generally, suboptimal channel
utilization) and inflexible (because the electronic devices may
need to transmit over the same duration time period using identical
data rates). In addition, trigger-based access and multi-user
transmission is not backwards compatible with existing or legacy
electronic devices.
SUMMARY
[0007] Some embodiments are described that relate to an access
point that transmits a trigger frame to a set of electronic devices
in a WLAN. In particular, during operation, an interface circuit in
the access point may receive, from one or more electronic devices
in the set of electronic devices, one or more requests to send
data. In response, the interface circuit may transmit the trigger
frame including information specifying an ordered list of
electronic devices in the set of electronic devices that are
allowed to transmit, and that groups the electronic devices in the
ordered list of electronic devices into a first subset of the
electronic devices and a second subset of the electronic devices.
Subsequently, the interface circuit may sequentially receive one or
more frames from the ordered list of electronic devices, where a
first group of the frames received from at least some of the first
subset of the electronic devices use single-user transmission and a
second group of frames received from at least some of the second
subset of the electronic devices use multi-user transmission.
[0008] A frame received from a given electronic device in the first
subset of the electronic devices may have an arbitrary length and
an arbitrary data rate (e.g., the lengths and/or the data rates of
two or more of the first subset of the frames received from the
first subset of the electronic devices may be different from each
other).
[0009] The information included in the trigger frame may specify a
maximum frame duration, and the one or more frames received from
the ordered list of electronic devices may have a duration that is
less than or equal to the maximum frame duration.
[0010] Furthermore, the information specifying the ordered list of
electronic devices may be included in a field following or after a
media access control (MAC) header.
[0011] Additionally, the information may specify explicit
triggering. In these embodiments, the interface circuit may
transmit an additional trigger frame to one or more of the
electronic device in the ordered list of electronic devices, and
the interface circuit may receive a frame in the first group of
frames or in the second group of frames in response to the
additional trigger frame.
[0012] Moreover, the information may specify that each of the
electronic devices in the ordered list of electronic devices
responds to the trigger frame.
[0013] In some embodiments, the interface circuit is compatible
with an IEEE 802.11 standard that includes trigger-based channel
access, and communicates with one or more legacy electronic devices
that are not compatible with the IEEE 802.11 standard (i.e., that
do not use multi-user trigger-based channel access).
[0014] Furthermore, the interface circuit may transmit, to the
ordered list of electronic devices, a block acknowledgment.
[0015] Additionally, the information may specify allocation of
resource units to the second subset of the electronic devices, and
the second group of frames may include data from one or more of the
second subset of the electronic devices in different frequency
channels. For example, the second group of frames may use
Orthogonal Frequency Division Multiple Access (OFDMA).
[0016] Other embodiments include operation with or by the
electronic device. In particular, during operation, an interface
circuit in the electronic device may transmit, to the access point,
a request to send data. In response, the interface circuit may
receive a trigger frame that includes information specifying an
ordered list of electronic devices in the set of electronic devices
that are allowed to transmit, where the information includes an
identifier of the electronic device and assigns the electronic
device to a first subset of the electronic devices or a second
subset of the electronic devices. Subsequently, the interface
circuit may transmit at least a portion of a frame to the access
point. When the electronic device is assigned to the first subset
of the electronic devices, the frame is transmitted at a temporal
position in a sequence of one or more frames from the first subset
of the electronic devices using single-user transmission.
Alternatively, when the electronic device is assigned to the second
subset of the electronic devices, at least the portion of the frame
is transmitted using multi-user transmission.
[0017] Note that, when the electronic device is assigned to the
first subset of the electronic devices, a transmit power of the
interface circuit may be proportional to a transmit bandwidth of
the electronic device (as opposed to a number of electronic devices
in the second subset of the electronic devices).
[0018] Moreover, the information may specify a maximum frame
duration, and the interface circuit may select an amount of data to
include in the frame and a data rate such that the frame has a
duration that is less than or equal to the maximum frame
duration.
[0019] Furthermore, the information may specify explicit
triggering. In these embodiments, the interface circuit may receive
an additional trigger frame from the access point, and the
interface circuit may transmit the frame in response to the
additional trigger frame.
[0020] Additionally, the information may specify that each of the
electronic devices in the ordered list of electronic devices
responds to the trigger frame, and the interface circuit may
transmit a null frame even when there is no queued data.
[0021] Note that the interface circuit may transmit the frame after
another frame is transmitted by at least a preceding electronic
device in the ordered list of electronic devices or a time slot
after an unused transmit opportunity of at least the preceding
electronic device.
[0022] Moreover, the interface circuit may receive, from the access
point, a block acknowledgment.
[0023] Furthermore, the information may specify allocation of
resource units to the second subset of the electronic devices, and
the frame may include data from the electronic device and/or one or
more other electronic devices in the second subset of the
electronic devices in different frequency channels. For example,
the frames may use OFDMA.
[0024] Other embodiments provide an interface circuit in the access
point or the electronic device.
[0025] Other embodiments provide a computer-program product for use
with the interface circuit in the access point and/or the
electronic device. This computer-program product includes
instructions for at least some of the aforementioned operations
performed by the interface circuit in the access point or the
electronic device.
[0026] Other embodiments provide a method for transmitting a
trigger frame or a frame. The method includes at least some of the
aforementioned operations performed by the interface circuit in the
access point or the electronic device.
[0027] This Summary is provided for purposes of illustrating some
exemplary embodiments, so as to provide a basic understanding of
some aspects of the subject matter described herein. Accordingly,
it will be appreciated that the above-described features are only
examples and should not be construed to narrow the scope or spirit
of the subject matter described herein in any way. Other features,
aspects, and advantages of the subject matter described herein will
become apparent from the following Detailed Description, Figures,
and Claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The included drawings are for illustrative purposes and
serve only to provide examples of possible structures and
arrangements for the disclosed systems and techniques for
intelligently and efficiently managing communication between
multiple associated user devices. These drawings in no way limit
any changes in form and detail that may be made to the embodiments
by one skilled in the art without departing from the spirit and
scope of the embodiments. The embodiments will be readily
understood by the following detailed description in conjunction
with the accompanying drawings, where like reference numerals
designate like structural elements.
[0029] FIG. 1 is a block diagram illustrating an example of
electronic devices communicating wirelessly.
[0030] FIG. 2 is a flow diagram illustrating an example of a method
for transmitting a trigger frame using one of the electronic
devices in FIG. 1.
[0031] FIG. 3 is a flow diagram illustrating an example of a method
for transmitting a frame using one of the electronic devices in
FIG. 1.
[0032] FIG. 4 is a flow diagram illustrating an example of
communication between electronic devices, such as the electronic
devices of FIG. 1.
[0033] FIG. 5 is a drawing illustrating an example trigger frame
communicated between at least two of the electronic devices in FIG.
1.
[0034] FIGS. 6, 7, and 8 illustrate timing diagrams of example
communication between electronic devices, such as the electronic
devices of FIG. 1.
[0035] FIG. 9 is a drawing illustrating an example trigger frame
communicated between at least two of the electronic devices in FIG.
1.
[0036] FIGS. 10 and 11 illustrate timing diagrams of example
communication between electronic devices, such as the electronic
devices of FIG. 1.
[0037] FIG. 12 is a flow diagram illustrating an example of a
method for transmitting a trigger frame using one of the electronic
devices in FIG. 1.
[0038] FIG. 13 is a flow diagram illustrating an example of a
method for transmitting a frame using one of the electronic devices
in FIG. 1.
[0039] FIG. 14 is a flow diagram illustrating an example of
communication between electronic devices, such as the electronic
devices of FIG. 1.
[0040] FIGS. 15, 16, and 17 illustrate timing diagrams of example
communication between electronic devices, such as the electronic
devices of FIG. 1.
[0041] FIG. 18 is a block diagram illustrating an example of one of
the electronic devices of FIG. 1.
[0042] Table 1 provides performance information for a multi-user
trigger-based channel-access technique.
[0043] Table 2 provides performance information for a Triggered
Wi-Fi Access Protocol (TWAP).
[0044] Note that like reference numerals refer to corresponding
parts throughout the drawings. Moreover, multiple instances of the
same part are designated by a common prefix separated from an
instance number by a dash.
DETAILED DESCRIPTION
[0045] An access point may transmit a trigger frame to a set of
electronic devices in a WLAN. In particular, during operation, the
access point may receive, from one or more electronic devices in a
set of electronic devices, one or more requests to send data. In
response, the access point may transmit the trigger frame that
includes information specifying an ordered list of electronic
devices in the set of electronic devices that are allowed to
transmit, and that groups the electronic devices in the ordered
list of electronic devices into a first subset of the electronic
devices and a second subset of the electronic devices.
Subsequently, the access point may sequentially receive one or more
frames from the ordered list of electronic devices, where a first
group of the frames received from at least some of the first subset
of the electronic devices use single-user transmission and a second
group of frames received from at least some of the second subset of
the electronic devices use multi-user transmission. After receiving
a last frame from the ordered list of electronic devices or after
an unused last transmit opportunity for the ordered list of
electronic devices, the access point may transmit a block
acknowledgment (BA) to the ordered list of electronic devices.
[0046] By specifying and selectively triggering the ordered list of
electronic devices, this communication technique may significantly
reduce the transmit power of the electronic devices in the WLAN
relative to many existing channel-access techniques, e.g., based
solely on OFDMA. In addition, the communication technique may
ensure efficient channel utilization (by eliminating or eliminating
wasted or unused bandwidth), reduced overhead, increased
flexibility (e.g., the electronic devices in the ordered list of
electronic devices may transmit different amounts of data and/or
may use different data rates), and/or may be backwards compatible
with existing/legacy electronic devices that do not use multi-user
trigger-based channel access. In the process, the communication
technique may reduce contention in the WLAN by facilitating
trigger-based channel access and may improve the communication
performance in the WLAN. Consequently, the communication technique
may improve the user experience when using the access point or one
of the electronic devices, and thus may increase customer
satisfaction and retention.
[0047] Note that the communication technique may be used during
wireless communication between electronic devices in accordance
with a communication protocol, such as: an IEEE 802.11 standard
(which is sometimes referred to as Wi-Fi). For example, the
communication technique may be used with IEEE 802.11ax, which is
used as an illustrative example in the discussion that follows.
However, this communication technique may also be used with a wide
variety of other communication protocols, and in access points and
electronic devices (such as portable electronic devices or mobile
devices) that can incorporate multiple different radio access
technologies (RATs) to provide connections through different
wireless networks that offer different services and/or
capabilities.
[0048] In particular, an electronic device can include hardware and
software to support a wireless personal area network (WPAN)
according to a WPAN communication protocol, such as those
standardized by the Bluetooth.RTM. Special Interest Group (in
Kirkland, Wash.) and/or those developed by Apple (in Cupertino,
Calif.) that are referred to as an Apple Wireless Direct Link
(AWDL). Moreover, the electronic device can communicate via: a
wireless wide area network (WWAN), a wireless metro area network
(WMAN) a WLAN, near-field communication (NFC), a cellular-telephone
or data network (such as using a third generation (3G)
communication protocol, a fourth generation (4G) communication
protocol, e.g., Long Term Evolution (LTE), LTE Advanced (LTE-A), a
fifth generation (5G) communication protocol, or other present or
future developed advanced cellular communication protocol) and/or
another communication protocol. In some embodiments, the
communication protocol includes a peer-to-peer communication
technique.
[0049] The electronic device, in some embodiments, can also operate
as part of a wireless communication system, which can include a set
of client devices, which can also be referred to as stations
(STAs), client devices, or client electronic devices,
interconnected to an access point, e.g., as part of a WLAN, and/or
to each other, e.g., as part of a WPAN and/or an `ad hoc` wireless
network, such as a Wi-Fi direct connection. In some embodiments,
the client device can be any electronic device that is capable of
communicating via a WLAN technology, e.g., in accordance with a
WLAN communication protocol. Furthermore, in some embodiments, the
WLAN technology can include a Wi-Fi (or more generically a WLAN)
wireless communication subsystem or radio, and the Wi-Fi radio can
implement an IEEE 802.11 technology, such as one or more of: IEEE
802.11a; IEEE 802.11b; IEEE 802.11g; IEEE 802.11-2007; IEEE
802.11n; IEEE 802.11-2012; IEEE 802.11ac; IEEE 802.11ax, or other
present or future developed IEEE 802.11 technologies.
[0050] In some embodiments, the electronic device can act as a
communications hub that provides access to a WLAN and/or to a WWAN
and, thus, to a wide variety of services that can be supported by
various applications executing on the electronic device. Thus, the
electronic device may include an `access point` that communicates
wirelessly with other electronic devices (such as using Wi-Fi), and
that provides access to another network (such as the Internet) via
IEEE 802.3 (which is sometimes referred to as `Ethernet`).
[0051] Additionally, it should be understood that the electronic
devices described herein may be configured as multi-mode wireless
communication devices that are also capable of communicating via
different 3G and/or second generation (2G) RATs. In these
scenarios, a multi-mode electronic device or user equipment (UE)
can be configured to prefer attachment to LTE networks offering
faster data rate throughput, as compared to other 3G legacy
networks offering lower data rate throughputs. For example, in some
implementations, a multi-mode electronic device is configured to
fall back to a 3G legacy network, e.g., an Evolved High Speed
Packet Access (HSPA+) network or a Code Division Multiple Access
(CDMA) 2000 Evolution-Data Only (EV-DO) network, when LTE and LTE-A
networks are otherwise unavailable.
[0052] In accordance with various embodiments described herein, the
terms `wireless communication device,` `electronic device,` `mobile
device,` `mobile station,` `wireless station,` `wireless access
point,` `station,` `access point` and `user equipment` (UE) may be
used herein to describe one or more consumer electronic devices
that may be capable of performing procedures associated with
various embodiments of the disclosure.
[0053] We now describe the communication technique. FIG. 1 presents
a block diagram 100 illustrating an example of electronic devices
communicating wirelessly. In particular, one or more electronic
devices 110 (such as a smartphone, a laptop computer, a notebook
computer, a tablet, or another such electronic device, which is
sometimes referred to as a `primary electronic device`) and access
point 112 may communicate wirelessly in a WLAN using an IEEE 802.11
communication protocol. Thus, electronic devices 110 may be
associated with access point 112. For example, electronic devices
110 and access point 112 may wirelessly communicate while:
detecting one another by scanning wireless channels, transmitting
and receiving beacons or beacon frames on wireless channels,
establishing connections (for example, by transmitting connect
requests), and/or transmitting and receiving packets or frames
(which may include the request and/or additional information, such
as data, as payloads). Note that access point 112 may provide
access to a network, such as the Internet, via an Ethernet
protocol, and may be a physical access point or a virtual or
`software` access point that is implemented on a computer or an
electronic device.
[0054] As described further below with reference to FIG. 18,
electronic devices 110 and access point 112 may include subsystems,
such as a networking subsystem, a memory subsystem, and a processor
subsystem. In addition, electronic devices 110 and access point 112
may include radios 114 in the networking subsystems. More
generally, electronic devices 110 and access point 112 can include
(or can be included within) any electronic devices with networking
subsystems that enable electronic devices 110 and access point 112
to wirelessly communicate with another electronic device. This can
include transmitting beacons on wireless channels to enable the
electronic devices to make initial contact with or to detect each
other, followed by exchanging subsequent data/management frames
(such as connect requests) to establish a connection, configure
security options (e.g., IPSec), transmit and receive packets or
frames via the connection, etc.
[0055] As can be seen in FIG. 1, wireless signals 116 (represented
by a jagged line) are communicated by radios 114-1 and 114-2 in
electronic device 110-1 and access point 112, respectively. For
example, as noted previously, electronic device 110-1 and access
point 112 may exchange packets using a Wi-Fi communication protocol
in a WLAN. For example, one or more of electronic devices 110
(which are sometimes referred to as a `set of electronic devices`)
may transmit one or more frames to access point 112 that include
one or more requests that indicate that at least a subset of
electronic devices 110 have uplink data. As illustrated further
below with reference to FIGS. 2-4, in response access point 112 may
transmit a trigger frame to the one or more of electronic devices
110. This trigger frame may include information specifying an
ordered list of electronic devices in the one or more of electronic
devices 110 that are allowed to transmit. For example, the
information specifying the ordered list of electronic devices (such
as identifiers of the electronic devices in the ordered list of
electronic devices) may be included in dedication information bytes
in a field following a MAC header.
[0056] In response to the trigger frame, the one or more of
electronic devices 110 in the ordered list of electronic devices
(such as electronic device 110-1) may sequentially transmit one or
more frames to access point 112 at temporal positions or access
opportunities that correspond to or are based on the ordered list
of electronic devices. For example, a given electronic device in
the ordered list of electronic devices may transmit a frame in a
sequences of one or more frames after another frame is transmitted
by a preceding electronic device in the ordered list of electronic
devices. Alternatively, the given electronic device may transmit a
frame in the sequence of one or more frames during a time slot
after an unused transmit opportunity of the preceding electronic
device in the ordered list of electronic devices.
[0057] In this trigger-based channel-access technique, the given
electronic device may select a data rate and a length of the frame
that it transmits in response to the trigger frame. For example,
the information in the trigger frame may specify a maximum frame
duration, and the frame from or transmitted by the given electronic
device may have a duration that is less than or equal to the
maximum frame duration. Thus, the lengths and/or the data rates of
two or more of the frames received from the ordered list of
electronic devices may be different from each other.
[0058] Moreover, the information in the trigger frame may specify
explicit triggering. In these embodiments, access point 112 may
transmit an additional trigger frame to the given electronic device
in the ordered list of electronic devices. In response, the given
electronic device may transmit the frame.
[0059] Furthermore, the information in the trigger frame may
specify that each of the electronic devices in the ordered list of
electronic devices may responds to the trigger frame (e.g., by
transmitting a frame). Therefore, access point 112 may receive a
frame in the frames from each of the electronic devices in the
ordered list of electronic devices. However, in other embodiments,
the electronic devices in the ordered list of electronic devices
may only transmit at their corresponding access opportunities
(which are indirectly specified by the ordered list of electronic
devices) if they have uplink or queued data.
[0060] After the last electronic device in the ordered list of
electronic devices has transmitted a frame or had an access
opportunity, access point 112 may transmit a block acknowledgment
to the ordered list of electronic devices. However, in other
embodiments access point 112 transmits an acknowledgment to each of
the electronic devices in the ordered list of electronic device
after these electronic devices transmit a frame.
[0061] Note that access point 112 and at least some of electronic
devices 110 may be compatible with an IEEE 802.11 standard that
includes trigger-based channel access (such as IEEE 802.11ax).
However, access point 112 and at least this subset of electronic
devices 110 may also communicate with one or more legacy electronic
devices that are not compatible with the IEEE 802.11 standard
(i.e., that do not use multi-user trigger-based channel access). As
described further below, the communication technique may also be
implemented using a legacy electronic device.
[0062] In addition, note that the transmit power of the electronic
devices in the ordered list of electronic devices may be
proportional to a transmit bandwidth of these electronic device (as
opposed to being proportional or scaling as a number of electronic
devices N in the ordered list of electronic devices).
[0063] In some embodiments, the information in the ordered list of
electronic devices may group the electronic devices in the ordered
list of electronic devices into a first subset of the electronic
devices and a second subset of the electronic devices.
Subsequently, access point 112 may sequentially receive one or more
frames from the ordered list of electronic devices. A first group
of one or more frames received from at least some of the first
subset of the electronic devices use single-user transmission and a
second group of one or more frames received from at least some of
the second subset of the electronic devices use multi-user
transmission (such as OFDMA). In these embodiments, the transmit
power of the first subset of the electronic devices may be
proportional to the transmit bandwidth of these electronic
devices.
[0064] In these ways, the communication technique may allow
electronic devices 110 and access point 112 to reduce contention in
the WLAN and to improve communication performance. These
capabilities may improve the user experience when using electronic
devices 110.
[0065] In the described embodiments, processing a packet or frame
in one of electronic devices 110 and access point 112 includes:
receiving wireless signals 116 encoding a packet or a frame;
decoding/extracting the packet or frame from received wireless
signals 116 to acquire the packet or frame; and processing the
packet or frame to determine information contained in the packet or
frame (such as data in the payload).
[0066] In general, the communication via the WLAN in the
communication technique may be characterized by a variety of
communication-performance metrics. For example, the
communication-performance metric may include: a received signal
strength (RSS), a data rate, a data rate for successful
communication (which is sometimes referred to as a `throughput`), a
latency, an error rate (such as a retry or resend rate), a
mean-square error of equalized signals relative to an equalization
target, inter-symbol interference, multipath interference, a
signal-to-noise ratio (SNR), a width of an eye pattern, a ratio of
number of bytes successfully communicated during a time interval
(such as 1-10 s) to an estimated maximum number of bytes that can
be communicated in the time interval (the latter of which is
sometimes referred to as the `capacity` of a communication channel
or link), and/or a ratio of an actual data rate to an estimated
data rate (which is sometimes referred to as `utilization`).
[0067] Although we describe the network environment shown in FIG. 1
as an example, in alternative embodiments, different numbers and/or
types of electronic devices may be present. For example, some
embodiments may include more or fewer electronic devices. As
another example, in other embodiments, different electronic devices
can be transmitting and/or receiving packets or frames.
[0068] FIG. 2 presents a flow diagram 200 illustrating an example
method for transmitting a trigger frame in accordance with some
embodiments. This method may be performed by an access point (and,
more generally, an electronic device), such as an interface circuit
in access point 112 in FIG. 1. During operation, the access point
optionally receives, from a set of electronic devices (which may
include one or more electronic devices), one or more requests to
send data (operation 210). The access point may transmit the
trigger frame (operation 212) that includes information specifying
an ordered list of electronic devices in the set of electronic
devices that are allowed to transmit. Note that the trigger frame
may be generated in response to the one or more requests to send
data and/or as a periodic opportunity to transmit without a
corresponding request. Subsequently, the access point may
sequentially receive one or more frames (operation 214) from the
ordered list of electronic devices.
[0069] In some embodiments, the access point optionally performs
one or more additional operations (operation 216). For example, the
information in the trigger frame may specify explicit triggering.
In these embodiments, the access point may optionally transmit an
additional trigger frame to a given electronic device in the
ordered list of electronic devices, and the access point may
optionally receive a frame in the frames in response to the
additional trigger frame. Alternatively or additionally, the
information in the trigger frame may optionally specify that each
of the electronic devices in the ordered list of electronic devices
responds to the trigger frame, and the access point may optionally
receive a frame in the frames from each of the electronic devices
in the ordered list of electronic devices.
[0070] Note that the access point may optionally transmit, to the
ordered list of electronic devices, a block acknowledgment after
receiving the last frame or after the last access opportunity
specified by the ordered list of electronic devices. Alternatively,
with the explicit triggering, the access point may optionally
transmit an acknowledgment to the given electronic device in the
ordered list of electronic devices after receiving a frame from the
given electronic device.
[0071] FIG. 3 presents a flow diagram 300 illustrating an example
method for transmitting a frame in accordance with some
embodiments. This method may be performed by an electronic device,
such as an interface circuit in electronic device 110-1 in FIG. 1.
During operation, the electronic device optionally transmits, to an
access point, a request to send data (operation 310). The
electronic device may receive a trigger frame (operation 312) that
includes information specifying an ordered list of electronic
devices in the set of electronic devices that are allowed to
transmit, where the information includes an identifier of the
electronic device. Subsequently, the electronic device may transmit
a frame to the access point (operation 314), where the frame is
transmitted at a temporal position (such as a time slot) in a
sequence of one or more frames from the ordered list of electronic
devices. In particular, the electronic device may transmit the
frame after another frame is transmitted by a preceding electronic
device in the ordered list of electronic devices or during a time
slot after an unused transmit opportunity of the preceding
electronic device.
[0072] In some embodiments, the electronic device optionally
performs one or more additional operations (operation 316). For
example, the information in the trigger frame may specify explicit
triggering. In these embodiments, the electronic device may
optionally receive an additional trigger frame, and the electronic
device may optionally transmit the frame in response to the
additional trigger frame. Alternatively or additionally, the
information in the trigger frame may optionally specify that each
of the electronic devices in the ordered list of electronic devices
responds to the trigger frame, and the electronic device may
optionally transmit a null frame even when there is no queued or
uplink data.
[0073] Note that the electronic device may optionally receive, from
the access point, a block acknowledgment after the last frame in
the sequence is transmitted by one of the ordered list of
electronic devices or after the last access opportunity specified
by the ordered list of electronic devices. Alternatively, with the
explicit triggering, the electronic device may optionally receive
an acknowledgment after receiving the frame from the electronic
device.
[0074] In some embodiments of the method illustrated in the flow
diagram 200 of FIG. 2 and/or the flow diagram 300 of FIG. 3, there
may be additional or fewer operations. Moreover, the order of the
operations may be changed, and/or two or more operations may be
combined into a single operation.
[0075] In some embodiments, at least some of the operations in the
method illustrated in the flow diagram 200 of FIG. 2 and/or the
flow diagram 300 of FIG. 3 are performed by interface circuits in
the access point or the electronic device. For example, at least
some of the operations may be performed by firmware executed by an
interface circuit, such as firmware associated with a MAC layer, as
well as one or more circuits in a physical layer in the interface
circuit.
[0076] The communication techniques are further illustrated in FIG.
4, which presents a flow diagram 400 illustrating an example of
communication between electronic devices 110 and access point 112.
In particular, interface circuits 410 in electronic devices 110 may
optionally transmit one or more requests 412 that indicate that at
least a subset of electronic devices 110 have uplink or queued
data. In response to receiving the one or more requests 412, an
interface circuit 414 in access point 112 may transmit trigger
frame 416 that includes information 418 specifying an ordered list
of electronic devices that are allowed to transmit.
[0077] After receiving trigger frame 416, electronic devices in the
ordered list of electronic devices (such as electronic devices
110-1 and 110-2) may transmit a sequence of one or more frames 422
in a sequence specified by the ordered list of electronic devices.
Moreover, interface circuit 414 may receive the one or more frames
422, and then may transmit a block acknowledgment (BA) 426 to the
electronic devices in the ordered list of electronic devices.
[0078] In embodiments where the information in trigger frame 416
specifies explicit triggering, interface circuit 414 may transmit
additional trigger frames 420 to the electronic devices in the
ordered list of electronic devices, and interface circuit 414 may
receive the one or more frames 422 in response to the additional
trigger frames 420. Furthermore, in these embodiments, instead of
block acknowledgment 426 interface circuit 414 may transmit
acknowledgments (ACK) 424 to the electronic devices in the ordered
list of electronic devices.
[0079] As described further below, the information may also specify
that the electronic devices in the ordered list of electronic
devices all transmit a frame in frames 422 in response to trigger
frame 416. Alternatively, the electronic devices in the ordered
list of electronic devices may transmit at their respective
temporal positions in the sequence of one or more frames 422 (which
is based on the ordered list of electronic devices) if they have
queued or uplink data. For example, interface circuit 410-2 may
transmit one of frames 422 after interface circuit 410-1 transmits
another of frames 422 because electronic device 110-1 may precede
electronic device 110-2 in the ordered list of electronic devices.
However, if interface circuit 410-1 does not use its transmit or
access opportunity, interface circuit 410-1 may transmit during a
subsequent time slot after the unused transmit opportunity.
Representative Embodiments
[0080] We now describe embodiments of the communication technique.
In contention-based channel-access techniques (such as EDCA), each
of the electronic devices in the WLAN independently contends for
the communication channel. However, as the number of electronic
devices in the WLAN increases (i.e., as the congestion increases),
the probability of a collision during channel access increases
exponentially.
[0081] In contrast, in previously proposed trigger-based
channel-access techniques with multi-user uplink transmission, an
access point may initiate the transmission by the electronic
devices. In particular, the access point may contend for the
communication channel on behalf of the electronic devices. When the
access point gains access, it may transmit a trigger frame to the
electronic devices. This high-efficiency trigger frame may specify
resource-unit allocation (or chunks of bandwidth) in OFDMA that
effectively splits or divides the available bandwidth among the
electronic devices. In response, the triggered electronic devices
simultaneously access the shared channel without collisions, and
simultaneously transmit their data using their allocated resource
units in OFDMA. Then, the access point acknowledges the received
frames using either a downlink multi-user block-acknowledgment
frame or a new frame that is sometimes referred to as a
`multi-station block acknowledgment` or an `m-STA BA.`
[0082] While these previously proposed trigger-based channel-access
techniques can address the high collision rate in congested
channels, there are some drawbacks. In particular, the previously
proposed trigger-based channel-access techniques often require new
physical layer capability to support multi-user uplink or downlink
communication. Moreover, unused resource units typically cannot be
used by other electronic devices and, thus, are wasted (i.e., there
is bandwidth loss). Stated differently, all the electronic devices
are allocated a chunk of bandwidth (or resource units) even when
they have no uplink data to transmit.
[0083] Furthermore, the access point usually needs to maintain the
buffer status of the electronic devices. Additionally, all of the
addressed electronic devices typically need to transmit for exact
same duration and at a data rate chosen by the access point. In
particular, because there is one OFDMA frame, the access point may
dictate the data rate and the duration (i.e., the length in bytes)
to all the electronic devices. This approach is in contrast to
current approaches in which the electronic devices determine these
parameters. Note that the management of rate adaptation for all the
electronic devices may be problematic if the link is
asymmetric.
[0084] If a data packet does not fit in the specified duration,
then an electronic device may have to cut or divide the data packet
to fit in a frame in real time (such as after the trigger frame and
during the short inter-frame space (SIFS). This is sometimes
referred to as `dynamic fragmentation.` Alternatively, the
electronic device may have to pad the frame, which results in more
bandwidth loss.
[0085] Furthermore, the previously proposed trigger-based
channel-access techniques often have large access overhead for a
single transmit opportunity (TXOP) transmission, such as
approximately 15% for a 1-ms duration uplink physical layer
convergence protocol (PLCP) protocol data unit (PPDU). In addition,
the energy consumption to transmit may be significantly increased,
such as proportionally to the number of electronic devices sharing
the full bandwidth allocation. This is because the transmit time is
increased because there is less bandwidth available because of the
sharing among the addressed electronic devices.
[0086] For example, if an access point triggers N electronic
devices (such as five electronic devices, 1 to 5) and provides an
acknowledgment using a multi-electronic device block-acknowledgment
frame, the access and protocol overhead may include: one EDCA
access, one high-efficiency trigger frame, two SIFS, and one
multi-electronic device block-acknowledgment frame (or uplink
multi-user block acknowledgment). In this example, the average data
bandwidth per electronic device is the maximum bandwidth divided by
N. Moreover, the energy to transmit per bit is N times more
expensive (for the same modulation coding scheme in a single-user
transmission). Consequently, the previously proposed trigger-based
channel-access techniques can be inefficient.
[0087] The trigger-based channel-access technique in the present
communication technique may provide several advantages relative to
the previously proposed trigger-based channel-access techniques.
Notably, the communication technique may allow implementation on
legacy hardware. Moreover, the communication technique may improve
interoperability and may provide fairness with legacy devices
(i.e., the communication technique may be backwards compatible).
Furthermore, the communication technique may provide efficient
channel utilization (including low protocol overhead and efficient
bandwidth utilization). For example, the communication technique
may avoid padding or the use of dummy frames. Additionally, in the
communication technique the transmit power may be proportional to
actual electronic-device transmit bandwidth and may not be related
to the number of electronic devices sharing the bandwidth. (Note
that the trigger frame may use high priority so that it shortens
the duration of the EDCA. This may be useful when there is high
congestion and/or high density such that multiple electronic
devices are competing for the channel access. In addition, note
that during time when the access point has reserved the channel
with a Network Allocation Vector (NAV), the access point may access
the channel more quickly. Thus, the communication technique may
provide efficient channel utilization in congested communication
channels managed by a central device, such as an access point.
[0088] In particular, the communication technique provides a
trigger-based channel-access technique, which may also be referred
to as a Triggered Wi-Fi Access Protocol (TWAP), for an access point
to send a trigger frame. TWAP may provide an alternative solution
to trigger-based channel access than the previously proposed
trigger-based channel-access techniques that involve multi-user
high-efficiency uplink transmissions.
[0089] During the communication technique, an access point may send
a trigger frame. This trigger frame may include a network
allocation vector or NAV duration. Moreover, the trigger frame may
include information that specifies an ordered list of electronic
devices (such as the association identifiers of the electronic
devices in the ordered list of electronic devices) that are allowed
to send a PPDU of any length and data rate selected by the
electronic devices. Thus, in the communication technique there may
not be dynamic fragmentation or padding required to fit into the
current transmit opportunity (i.e., the NAV).
[0090] After receiving the trigger frame and waiting a Short
Inter-Frame Space (SIFS) time, the first addressed electronic
device may be allowed to send an uplink PPDU. Alternatively if the
designated electronic device has nothing to send (or is in doze
state or a low-power mode), the electronic device may remain
silent.
[0091] Then, the second addressed electronic device may access the
air or the communication channel a SIFS time after the transaction
by the first electronic device (including an acknowledgment) or a
Point Coordination Function (PCF) Inter-frame Space (PIFS) time
(i.e., the SIFS plus one slot) following the trigger frame if the
first electronic device did not use its opportunity to
transmit.
[0092] Moreover, the third (and subsequent) addressed electronic
devices can access the air or the communication channel a SIFS time
after the transaction by the previous electronic device (including
an acknowledgement) or a slot time after the previous unused
transmit opportunity.
[0093] Furthermore, once the last addressed electronic device has
transmitted (or timed out), the access point might send a
contention free-end (CF-End) frame to end the current transmit
opportunity (if it was not fully used).
[0094] We now describe the format of the trigger frame and examples
of the communication technique in more detail. FIG. 5 presents a
drawing illustrating a trigger frame 500 communicated between at
least two of the electronic devices in FIG. 1, such as access point
112 and electronic device 110-1. In particular, trigger frame 500
may include: frame control 510 (which, e.g., may be 2B), duration
512 (which, e.g., may be 2B and may specify the NAV), a receive
address (RA) 514 (such as broadcast), a transmit address (TA) 516,
which, e.g., may be 6B and may specify the basic service set
identifier (BSSID) of the access point, the uplink (UL) PPDU
maximum duration 518 (which, e.g., may be 2B and may have units of
microseconds), trigger options 520 (which, e.g., may be 1B), an
association identifier (AID) list length 522 (which, e.g., may be
1B) and AID list 524 (which, e.g., may have a variable length).
While example lengths in bytes are provided, any/all of the lengths
may be modified in other implementations, and one or more fields
may be added, removed, or modified in other trigger frame
implementations.
[0095] Trigger frame 500 may be a new control frame. Note that it
may not include allocation of resource units. Instead, it may
specify an ordered list of electronic devices (AID list 524) that
are addressed (such as electronic devices 1, 3 and 5) that can use
uplink communication using time-domain multiple access in the order
specified in AID list 524. These electronic devices can use any
data rate do long as it fits in the UL PPDU maximum duration 518.
The purpose of AID list 524 is to advertise a sorted list of AIDs
that are selected to use the current TXOP allocated by the access
point.
[0096] Note that, if non-zero, the UL PPDU maximum duration 518
defines the maximum allowed duration for UL PPDU frames. However,
if the UL PPDU maximum duration 518 is zero, the PPDU duration is
limited by the NAV. Moreover, trigger options 520 may specify
several optional TWAP settings or parameters. For example, an
explicit trigger value of `1` may specify explicit triggering.
During explicit triggering, the electronic devices in AID list 524
may be expected to transmit only following an explicit trigger from
the access point in the TXOP. Otherwise, the electronic devices can
transmit according to their order in AID list 524. Furthermore, a
UL required value of `1` may specify that the electronic devices in
AID list 524 are expected to transmit even if they have no data to
send (in these embodiments a quality-of-service or QoS null frame
may be sent). Otherwise, electronic devices without data can skip
their transmission opportunity. Additionally, an m-STA BA value of
`1` may specify that the access point may acknowledge
electronic-device UL data using a single m-STA BA frame at the end
of the TWAP TXOP. Otherwise, an immediate acknowledge may follow
each UL PPDU from each of the electronic devices in AID list
524.
[0097] We now describe several access protocol examples. During the
communication technique, in response to one or more electronic
devices sending requests that specify bandwidth and latency, the
access point may transmit a trigger frame with an ordered list of
electronic devices. These electronic devices may transmit at their
sequential times if they have uplink or queued data. Otherwise, an
electronic device may not transmit. When that occurs, the next
electronic device in the ordered list of electronic devices may
wait at least one slot before transmitting. Note that the NAV may
be up to 32 ms by standard. In order to maintain firmness with
other devices on the channel, a typical value of up to 8 ms may be
used. If there is not enough time for an electronic device (such as
the last electronic device in the ordered list of electronic
devices) to transmit, this electronic device may not transmit
anything. Instead, the electronic device may wait to transmit in
response to the next trigger frame.
[0098] FIG. 6 presents a timing diagram 600 illustrating an example
of communication between access point 112 and electronic devices
110 in FIG. 1. In this example, the access point may trigger at
least three electronic devices (1 to 3), all of which may have
uplink traffic. Each triggered device transmits in its designated
slot. In FIG. 6, note that m-STA BA equals `0` (i.e., no multi-STA
BA will be transmitted, instead individual BAs will be sent) and
explicit Trigger equals `0` (i.e., the frames will not be
separately triggered).
[0099] FIG. 7 presents a timing diagram 700 illustrating an example
of communication between access point 112 and electronic devices
110 in FIG. 1. In this example, the access point may trigger, e.g.,
five electronic devices (1 to 5), but only electronic devices 2 and
5 have uplink traffic. In FIG. 7, m-STA BA equals `0,` explicit
trigger equals `0` and required equals `0` (i.e., each electronic
device is not required to transmit even when it has no data). Each
device transmits in its designated order, after an unused slot
associated with the preceding device. Because the ordered list of
electronic devices completes transmission in less than the allotted
time, the access point may truncate the NAV.
[0100] FIG. 8 presents a timing diagram 800 illustrating an example
of communication between access point 112 and electronic devices
110 in FIG. 1. In this example, the access point may trigger three
electronic devices (1 to 3), all of which may have uplink traffic.
Each triggered electronic device transmits in its designated slot,
and a multi-STA BA (m-STA BA) is transmitted after the last uplink
transmission. In FIG. 8, note that m-STA BA equals `1` and explicit
Trigger equals `0.`
[0101] We now describe the explicit trigger packet format. The
purpose of the explicit trigger frame is to trigger a particular
electronic device during the TWAP TXOP as an option to overcome
potential hidden node issues where some of the electronic devices
in the ordered list of electronic devices are unable to hear one or
more other electronic devices in the ordered list. FIG. 9 presents
a drawing illustrating a trigger frame 900 communicated between two
or more of the electronic devices in FIG. 1, such as access point
112 and electronic device 110-1. While explicit trigger frame 900
has the same format as trigger frame 500, the values in some of the
fields are different. In particular, receive address 514 may be the
MAC address of the electronic device, AID list length 522 may be
`1` (specifying a single electronic device), and AID list 524 may
include the AID of the electronic device.
[0102] FIG. 10 presents a timing diagram 1000 illustrating an
example of communication between access point 112 and electronic
devices 110 in FIG. 1. In this example, the access point may
trigger three electronic devices (1 to 3), only electronic devices
1 and 3 may have uplink traffic. In particular, the electronic
devices may be triggered one-by-one by the access point. This
approach may eliminate the need for the electronic devices to count
slots/transmit times (instead, this is handled by the access
point). In FIG. 10, note that m-STA BA equals `1,` explicit Trigger
equals `1` and required equals `0.`
[0103] Note that if the transmission takes a fixed duration, then
electronic devices that are not addressed can go to sleep
immediately. Otherwise, if the transmission is shorter than maximum
time and an electronic device has gone to Doze, then the electronic
device may sleep until the end of the reserved time and the
electronic device may not be available to receive transmissions
from the access point.
[0104] FIG. 11 presents a timing diagram 1100 illustrating an
example of communication between access point 112 and electronic
devices 110 in FIG. 1. In this example, the access point may
trigger three electronic devices (1 to 3), all of which may have
uplink traffic. In FIG. 11, note that m-STA BA equals `1,` explicit
Trigger equals `1` and required equals `1.`
[0105] The communication technique may be implemented on legacy
devices, i.e., using legacy hardware. In particular, following a
TWAP Trigger frame, each addressed electronic device may configure
its air access parameters to: arbitration inter-frame spacing
(AIFS) equal to SIFS plus (N-1) times slot, where N equals the AID
order in the ordered list of electronic devices (starting from
one); and the contention window (CW) equal to `0` (always draw back
off equal to `0`). Following a receive frame during a TXOP without
explicit triggering, each addressed electronic device may configure
its air access parameters to: AIFS equal to SIFS plus (R-1) times
slot, where R equals the AID order in the ordered list of
electronic devices from here or this point; and the CW equal to `0`
(always draw back off equal to `0`). For example, for the fifth
electronic device in the ordered list of electronic devices, AIFS
equals SIFS plus four slots.
[0106] Alternatively, with explicit triggering, an addressed
electronic device waits for the access point to transmit a trigger
(which is simpler, but has higher overhead). In particular, the
TXOP obtained for the first trigger frame (when NAV is not set) may
use EDCA access to enable random and fair access to all electronic
devices in the area. EDCA parameters may be good for the access
point, but some backoff calculation should be included. When the
access point has reserved a duration for its transmissions, the
access point may access the channel after a SIFS or PIFS, if it
does not receive response. Thus the channel access overhead may be
reduced and transmission time use may be efficient, i.e., the
reserved transmission time may be used as efficiently as
possible.
[0107] Tables 1 and 2, respectively, provide a comparison of the
performance of multi-user trigger-based channel access (MU-TBCA)
and TWAP. In these examples, there are N electronic devices, with
20 MHz bandwidth, a number of spatial streams of `1,` User Datagram
Protocol (UDP) transmit BE, maximum throughput (modulation coding
scheme of 7 and 0.8 .mu.s guard interval, m-STA BA equal to `0` and
explicit trigger equal to `0.` Note that for TWAP, the TXOP per
electronic device is 1000 .mu.s. In addition, the TWAP throughput
gain is because of the increased BW relative to OFDMA.
TABLE-US-00001 TABLE 1 Bandwidth (MHz) 20 20 20 RU tones 242 106 52
N STAs 1 2 4 EDCA access overhead (.mu.s) 104 104 104 Trigger
overhead (+SIFS) (.mu.s) 100 100 100 PPDU duration (.mu.s) 852 1852
3852 Block acknowledgment overhead 48 48 48 (+SIFS) (.mu.s) Total
Overhead (N STAs) (.mu.s) 252 252 252 Physical layer rate (Mbps) 86
37.5 17.6 Throughput per STA (Mbps) 66.4 33 16.5 Transmit power
penalty ratio 1 2.29 4.89
TABLE-US-00002 TABLE 2 Bandwidth (MHz) 20 20 20 RU tones 242 106 52
N STAs 1 2 4 EDCA access overhead (.mu.s) 104 104 104 Trigger
overhead (+SIFS) (.mu.s) 100 100 100 PPDU duration (.mu.s) 852 1852
3852 Block acknowledgment overhead 48 48 48 (+SIFS) (.mu.s) Total
Overhead (N STAs) (.mu.s) 252 252 252 Physical layer rate (Mbps) 86
37.5 17.6 Throughput per STA(Mbps) 66.4 34.7 18.3 TWAP throughput
gain (%) 0 5 11
Additional Embodiments
[0108] FIG. 12 illustrates a flow diagram 1200 of an example method
for transmitting a trigger frame in accordance with some
embodiments. This method may be performed by an access point (and,
more generally, an electronic device), such as an interface circuit
in access point 112 in FIG. 1. During operation, the access point
optionally receives, from a set of electronic devices (which may
include one or more electronic devices), one or more requests to
send data (operation 1210). The access point may transmit the
trigger frame (operation 1212) that includes information specifying
an ordered list of electronic devices in the set of electronic
devices that are allowed to transmit, and that groups the
electronic devices in the ordered list of electronic devices into a
first subset of the electronic devices and a second subset of the
electronic devices. Subsequently, the access point may sequentially
receive one or more frames (operation 1214) from the ordered list
of electronic devices, where a first group of the frames received
from at least some of the first subset of the electronic devices
use single-user transmission and a second group of frames received
from at least some of the second subset of the electronic devices
use multi-user transmission.
[0109] Note that a frame received from a given electronic device in
the first subset of the electronic devices may have an arbitrary
length, e.g., up to a maximum threshold, and an arbitrary data rate
(i.e., the lengths and/or the data rates of two or more of the
first subset of the frames received from the first subset of the
electronic devices may be different from each other).
[0110] In some embodiments, the access point optionally performs
one or more additional operations (operation 1216). For example,
the information in the trigger frame may specify explicit
triggering. In these embodiments, the access point may optionally
transmit an additional trigger frame to one or more of the
electronic devices in the ordered list of electronic devices, and
the access point may optionally receive a frame in the first group
of frames or the second group of frames in response to the
additional trigger frame. Alternatively or additionally, the
information in the trigger frame may optionally specify that each
of the electronic devices in the ordered list of electronic devices
responds to the trigger frame.
[0111] Moreover, the information may optionally specify a maximum
frame duration, and the one or more frames may have a duration that
is less than or equal to the maximum frame duration. Furthermore,
the information may optionally specify allocation of resource units
to the second subset of the electronic devices, and the second
group of frames may include data from one or more of the second
subset of the electronic devices in different frequency channels.
For example, the second group of frames may use OFDMA.
[0112] Note that the access point may optionally transmit, to the
ordered list of electronic devices, a block acknowledgment after
receiving the last frame or after the last access opportunity
specified by the ordered list of electronic devices. Alternatively,
with the explicit triggering, the access point may optionally
transmit an acknowledgment to a given electronic device in the
ordered list of electronic devices after receiving a frame from the
given electronic device.
[0113] FIG. 13 presents a flow diagram 1300 illustrating an example
method for transmitting a frame in accordance with some
embodiments. This method may be performed by an electronic device,
such as an interface circuit in electronic device 110-1 in FIG. 1.
During operation, the electronic device optionally transmits, to an
access point, a request to send data (operation 1310). The
electronic device may receive a trigger frame (operation 1312) that
includes information specifying an ordered list of electronic
devices in the set of electronic devices that are allowed to
transmit, where the information includes an identifier of the
electronic device and assigns the electronic device to a first
subset of the electronic devices or a second subset of the
electronic devices. Subsequently, the electronic device may
transmit at least a portion of a frame to the access point
(operation 1314). When the electronic device is assigned to the
first subset of the electronic devices, the frame may be
transmitted at a temporal position (such as a time slot) in a
sequence of one or more frames from the first subset of the
electronic devices using single-user transmission. Alternatively,
when the electronic device is assigned to the second subset of the
electronic devices, at least the portion of the frame (such as a
particular frequency channel or resource unit) may be transmitted
using multi-user transmission. In particular, the electronic device
may transmit the frame after another frame is transmitted by at
least a preceding electronic device in the ordered list of
electronic devices or during a time slot after an unused transmit
opportunity of at least the preceding electronic device.
[0114] In some embodiments, the electronic device optionally
performs one or more additional operations (operation 1316). For
example, the information in the trigger frame may specify explicit
triggering. In these embodiments, the electronic device may
optionally receive an additional trigger frame, and the electronic
device may optionally transmit the frame in response to the
additional trigger frame. Alternatively or additionally, the
information in the trigger frame may optionally specify that each
of the electronic devices in the ordered list of electronic devices
responds to the trigger frame, and the electronic device may
optionally transmit a null frame even when there is no queued or
uplink data.
[0115] Note that the electronic device may optionally receive, from
the access point, a block acknowledgment after the last frame in
the sequence is transmitted by at least one of the ordered list of
electronic devices or after the last access opportunity specified
by the ordered list of electronic devices. Alternatively, with the
explicit triggering, the electronic device may optionally receive
an acknowledgment after receiving the frame from the electronic
device.
[0116] Moreover, note that, when the electronic device is assigned
to the first subset of the electronic devices, a transmit power of
the interface circuit in the electronic device may be proportional
to a transmit bandwidth of the electronic device (as opposed to a
number of electronic devices in the second subset of the electronic
devices). Furthermore, the information may optionally specify a
maximum frame duration, and the electronic device may optionally
select an amount of data to include in the frame and a data rate
such that the frame has a duration that is less than or equal to
the maximum frame duration.
[0117] Additionally, the information may optionally specify
allocation of resource units to the second subset of the electronic
devices, and the frame may optionally include data from the
electronic device and/or one or more other electronic devices in
the second subset of the electronic devices in different frequency
channels. For example, the frame may use OFDMA.
[0118] In some embodiments of the methods illustrated by the flow
diagram 1200 of FIG. 12 and/or the flow diagram 1300 of FIG. 13,
there may be additional or fewer operations. Moreover, the order of
the operations may be changed, and/or two or more operations may be
combined into a single operation.
[0119] In some embodiments, at least some of the operations of the
methods illustrated by the flow diagram 1200 of FIG. 12 and/or the
flow diagram 1300 of FIG. 13 are performed by interface circuits in
the access point or the electronic device. For example, at least
some of the operations may be performed by firmware executed by an
interface circuit, such as firmware associated with a MAC layer, as
well as one or more circuits in a physical layer in the interface
circuit.
[0120] The communication techniques are further illustrated in FIG.
14, which presents a flow diagram 1400 illustrating an example of
communication between electronic devices 110 and access point 112.
In particular, interface circuits 1410 in electronic devices 110
may optionally transmit one or more requests 1412 that indicate
that at least a subset of electronic devices 110 have uplink or
queued data. In response to receiving the one or more optional
requests 1412, an interface circuit 1414 in access point 112 may
transmit trigger frame 1416 that includes information 1418
specifying an ordered list of electronic devices that are allowed
to transmit, and that groups electronic devices 110 in the ordered
list of electronic devices into a first subset of the electronic
devices and a second subset of the electronic devices. The trigger
frame 1416 can identify, e.g., one or more devices that transmitted
a request and/or one or more electronic devices based on a
period.
[0121] After receiving trigger frame 1416, electronic devices in
the first subset of the electronic devices (such as electronic
devices 110-1 and 110-2) may transmit a sequence of one or more
frames 1422 in a sequence specified by the ordered list of
electronic devices using single-user transmission (in which one
member of the first subset of the electronic devices transmits at a
given time). Moreover, electronic devices in the second subset of
the electronic devices (such as, in an alternate embodiment,
electronic devices 110-1 and 110-2) may transmit at least a portion
of one or more frames, such as data in a frequency channel or
resource unit in frame 1424, individually or in conjunction with
each other using multi-user transmission (in which electronic
devices 110-1 and/or 110-2 transmit portions of the one or more
frames 1424 concurrently).
[0122] After interface circuit 1414 receives the one or more frames
1422 and/or 1424, then interface circuit 1414 may transmit a block
acknowledgment 1428 to the electronic devices in the ordered list
of electronic devices.
[0123] In embodiments where the information in trigger frame 1416
specifies explicit triggering, interface circuit 1414 may transmit
additional trigger frames 1420 to the electronic devices in the
ordered list of electronic devices, and interface circuit 1414 may
receive the one or more frames 1422 and/or 1424 in response to the
additional trigger frames 1420. Furthermore, in these embodiments,
interface circuit 1414 may transmit acknowledgments 1426 to the
electronic devices in the ordered list of electronic devices
instead of block acknowledgment 1428.
[0124] As described further below, the information may also specify
that the electronic devices in the ordered list of electronic
devices all transmit a frame in frames 1422 and/or 1424 in response
to trigger frame 1416. Alternatively, the electronic devices in the
ordered list of electronic devices may transmit at their respective
temporal positions in the sequence of one or more frames 1422
and/or 1424 (which is based on the ordered list of electronic
devices) if they have queued or uplink data. For example, interface
circuit 1410-2 may transmit one of frames 1422 after interface
circuit 1410-1 transmits another of frames 1422 because electronic
device 110-1 may precede electronic device 110-2 in the first
subset of the electronic devices. However, if interface circuit
1410-1 does not use its transmit or access opportunity, interface
circuit 1410-1 may transmit during a subsequent time slot after the
unused transmit opportunity.
Representative Additional Embodiments
[0125] We now describe additional embodiments of the communication
technique. In some of these additional embodiments, an electronic
device may be allowed to report its restriction, request or
preference on how it want the access point to schedule its channel
access. In particular, the electronic device may indicate whether
or not it does not want to be scheduled with other electronic
devices, i.e., whether or not a trigger frame may allocate all of
the bandwidth to this electronic device if the access point decides
to schedule transmission for this electronic device.
[0126] Alternatively, the electronic device may define the minimum
channel width, duration and number of spatial streams (NSS) for its
scheduled uplink transmissions. For example, the electronic device
may request half of the bandwidth.
[0127] In general, one or more restrictions provided by an
electronic device may be in use by the access point at a given
time.
[0128] When a restriction is set, the access point may schedule
smaller or fewer resources for the electronic device. Note that
this restriction may be applied to all the communication operations
performed with the electronic device, during a target wake-up time
(TWT) window or at times other than a TWT window. If the
restriction is applied to all the communication operations or
during the entire operation of the electronic device, then an
indication specifying the restriction may be exchanged between the
electronic device and the access point during association.
[0129] For example, a Transmission Operation Mode Indication (TOMI)
may be used to convey the restriction for the entire operation of
the electronic device. Alternatively or additionally, a new
information element (IE) or a new field may be defined to indicate
the restriction from the electronic device. When the restriction
only applies to the TWT window, then the indication may be conveyed
or communication through the TWT negotiation. For example, some
reserved bits in a TWT request frame may be used for this
purpose.
[0130] Thus, a restriction may indicate whether or not the
electronic device is willing to share the bandwidth or not, and if
yes how much it is willing to share.
[0131] In some of the additional embodiments, some of the
electronic devices (i.e., the second subset) are able to use OFDMA,
while other electronic devices (i.e., the first subset) prefer to
use the whole bandwidth during their transmissions. In these
embodiments, the trigger frame exchanged between the access point
and the electronic devices may include an order of the electronic
devices, and a grouping of the electronic devices in the frame
exchange sequence to the first subset that uses single-user
transmission and the second subset that uses multi-user
transmission. For example, the trigger frame may indicate:
(electronic device 1, single user), (electronic device 2,
electronic device 3, OFDMA allocation parameters), (electronic
device 4, electronic device 5, OFDMA allocation parameters), and
(electronic device 6, single user).
[0132] FIG. 15 presents a timing diagram 1500 illustrating an
example of communication between electronic devices, such as the
electronic devices of FIG. 1. In particular, electronic devices 1
and 6 are in the first subset of the electronic devices, and
electronic device 2, 3, 4 and 5 are in the second subset of the
electronic devices.
[0133] Because there may be hidden nodes, in some embodiments the
access point may transmit an additional trigger frame before each
or some electronic device's transmission. The additional frame may
be a clear-to-send (CTS). Moreover, because CTS is a control frame
that only has one address field, it may be set to an address of the
STA that is allowed to transmit (instead of the address of the
access point). More generally, the additional trigger frame may be
a trigger frame that includes the address of a particular
electronic device that is allowed to transmit. FIG. 16 presents a
timing diagram 1600 illustrating an example of communication
between electronic devices, such as the electronic devices of FIG.
1, with the explicit triggering.
[0134] Furthermore, in some embodiments a short trigger frame (Tf)
is used to implement polling during a TWT window. Note that the
short trigger frame may be used in addition to or separately from
the trigger frame described previously (which is sometimes referred
to as a `sequential trigger frame`). Thus, short Trigger frame may
be used in TWT schedule and/or the TWT schedule may be signaled to
start with the trigger frame or with short trigger frame in the TWT
setup. Note that the short trigger frame may reduce transmission
overhead. FIG. 17 presents a timing diagram illustrating an example
of communication between electronic devices, such as the electronic
devices of FIG. 1, with the short trigger frame during a TWT
window.
[0135] The access point or the electronic device may define the
duration of each PPDU transmission or frame. Thus, the duration may
be the maximum duration or a specified duration for a particular
electronic device. Note that the duration may be defined on a
frame-by-frame basis. When the access point defines the duration,
the duration may be specified by the information in the trigger
frame.
[0136] Similarly, the access point or the electronic device may
define a modulation coding scheme used by the electronic device
during each PPDU transmission or frame. Note that the modulation
coding scheme may be changed on a frame-by-frame basis. When the
access point defines the modulation coding scheme, the modulation
coding scheme may be specified by the information in the trigger
frame.
[0137] Furthermore, the access point or the electronic device may
define a number of spatial streams (NSS) in multiple input multiple
output (MIMO) that may be used by the electronic device during each
PPDU transmission or frame. Note that the NSS may be changed on a
frame-by-frame basis. When the access point defines the NSS, the
NSS may be specified by the information in the trigger frame.
[0138] In summary, in some embodiments of the communication
technique the electronic device provides an indication to the
access point regarding its multi-user transmission restriction. For
example, the electronic device may indicate that it is not allowed
to be grouped with other electronic devices in a multi-user or an
OFDMA transmission. Alternatively, the electronic device may
indicate that it is ok to be grouped with other electronic devices
in a multi-user or an OFDMA transmission. The indication can be
applied to either entire operation, to a TWT window or to times
other than a TWT window.
[0139] Moreover, in some embodiments the trigger frame specifies a
first subset of the electronic devices that use single-user
transmission and a second subset of the electronic devices that use
multi-user transmissions in addition to the ordered list of
electronic devices. Furthermore, to better protect each electronic
device's transmissions, the frame exchange sequence may include an
additional trigger frame.
[0140] We now describe embodiments of an electronic device. FIG. 18
presents a block diagram of an electronic device 1800 (which may be
an access point, another electronic device, such as a station or a
legacy electronic device) in accordance with some embodiments. This
electronic device includes processing subsystem 1810, memory
subsystem 1812, and networking subsystem 1814. Processing subsystem
1810 includes one or more devices configured to perform
computational operations. For example, processing subsystem 1810
can include one or more microprocessors, application-specific
integrated circuits (ASICs), microcontrollers, programmable-logic
devices, and/or one or more digital signal processors (DSPs).
[0141] Memory subsystem 1812 includes one or more devices for
storing data and/or instructions for processing subsystem 1810 and
networking subsystem 1814. For example, memory subsystem 1812 can
include dynamic random access memory (DRAM), static random access
memory (SRAM), a read-only memory (ROM), flash memory, and/or other
types of memory. In some embodiments, instructions for processing
subsystem 1810 in memory subsystem 1812 include: one or more
program modules or sets of instructions (such as program module
1822 or operating system 1824), which may be executed by processing
subsystem 1810. For example, a ROM can store programs, utilities or
processes to be executed in a non-volatile manner, and DRAM can
provide volatile data storage, and may store instructions related
to the operation of electronic device 1800. Note that the one or
more computer programs may constitute a computer-program mechanism,
a computer-readable storage medium or software. Moreover,
instructions in the various modules in memory subsystem 1812 may be
implemented in: a high-level procedural language, an
object-oriented programming language, and/or in an assembly or
machine language. Furthermore, the programming language may be
compiled or interpreted, e.g., configurable or configured (which
may be used interchangeably in this discussion), to be executed by
processing subsystem 1810. In some embodiments, the one or more
computer programs are distributed over a network-coupled computer
system so that the one or more computer programs are stored and
executed in a distributed manner.
[0142] In addition, memory subsystem 1812 can include mechanisms
for controlling access to the memory. In some embodiments, memory
subsystem 1812 includes a memory hierarchy that includes one or
more caches coupled to a memory in electronic device 1800. In some
of these embodiments, one or more of the caches is located in
processing subsystem 1810.
[0143] In some embodiments, memory subsystem 1812 is coupled to one
or more high-capacity mass-storage devices (not shown). For
example, memory subsystem 1812 can be coupled to a magnetic or
optical drive, a solid-state drive, or another type of mass-storage
device. In these embodiments, memory subsystem 1812 can be used by
electronic device 1800 as fast-access storage for often-used data,
while the mass-storage device is used to store less frequently used
data.
[0144] Networking subsystem 1814 includes one or more devices
configured to couple to and communicate on a wired and/or wireless
network (i.e., to perform network operations), including: control
logic 1816, an interface circuit 1818 and a set of antennas 1820
(or antenna elements) in an adaptive array that can be selectively
turned on and/or off by control logic 1816 to create a variety of
optional antenna patterns or `beam patterns.` (While FIG. 18
includes set of antennas 1820, in some embodiments electronic
device 1800 includes one or more nodes, such as nodes 1808, e.g., a
pad, which can be coupled to set of antennas 1820. Thus, electronic
device 1800 may or may not include set of antennas 1820.) For
example, networking subsystem 1814 can include a Bluetooth.TM.
networking system, a cellular networking system (e.g., a 3G/4G/5G
network such as UMTS, LTE, etc.), a universal serial bus (USB)
networking system, a networking system based on the standards
described in IEEE 802.11 (e.g., a Wi-Fi.RTM. networking system), an
Ethernet networking system, and/or another networking system.
[0145] Networking subsystem 1814 includes processors, controllers,
radios/antennas, sockets/plugs, and/or other devices used for
coupling to, communicating on, and handling data and events for
each supported networking system. Note that mechanisms used for
coupling to, communicating on, and handling data and events on the
network for each network system are sometimes collectively referred
to as a `network interface` for the network system. Moreover, in
some embodiments a `network` or a `connection` between the
electronic devices does not yet exist. Therefore, electronic device
1800 may use the mechanisms in networking subsystem 1814 for
performing simple wireless communication between the electronic
devices, e.g., transmitting advertising or beacon frames and/or
scanning for advertising frames transmitted by other electronic
devices.
[0146] Within electronic device 1800, processing subsystem 1810,
memory subsystem 1812, and networking subsystem 1814 are coupled
together using bus 1828 that facilitates data transfer between
these components. Bus 1828 may include an electrical, optical,
and/or electro-optical connection that the subsystems can use to
communicate commands and data among one another. Although only one
bus 1828 is shown for clarity, different embodiments can include a
different number or configuration of electrical, optical, and/or
electro-optical connections among the subsystems.
[0147] In some embodiments, electronic device 1800 includes a
display subsystem 1826 for displaying information on a display,
which may include a display driver and the display, such as a
liquid-crystal display, a multi-touch touchscreen, etc. Display
subsystem 1826 may be controlled by processing subsystem 1810 to
display information to a user (e.g., information relating to
incoming, outgoing, or an active communication session).
[0148] Electronic device 1800 can also include a user-input
subsystem 1830 that allows a user of the electronic device 1800 to
interact with electronic device 1800. For example, user-input
subsystem 1830 can take a variety of forms, such as: a button,
keypad, dial, touch screen, audio input interface, visual/image
capture input interface, input in the form of sensor data, etc.
[0149] Electronic device 1800 can be (or can be included in) any
electronic device with at least one network interface. For example,
electronic device 1800 may include: a cellular telephone or a
smartphone, a tablet computer, a laptop computer, a notebook
computer, a personal or desktop computer, a netbook computer, a
media player device, an electronic book device, a MiFi.RTM. device,
a smartwatch, a wearable computing device, a portable computing
device, a consumer-electronic device, an access point, a router, a
switch, communication equipment, test equipment, as well as any
other type of electronic computing device having wireless
communication capability that can include communication via one or
more wireless communication protocols.
[0150] Although specific components are used to describe electronic
device 1800, in alternative embodiments, different components
and/or subsystems may be present in electronic device 1800. For
example, electronic device 1800 may include one or more additional
processing subsystems, memory subsystems, networking subsystems,
and/or display subsystems. Additionally, one or more of the
subsystems may not be present in electronic device 1800. Moreover,
in some embodiments, electronic device 1800 may include one or more
additional subsystems that are not shown in FIG. 18. Also, although
separate subsystems are shown in FIG. 18, in some embodiments some
or all of a given subsystem or component can be integrated into one
or more of the other subsystems or component(s) in electronic
device 1800. For example, in some embodiments program module 1822
is included in operating system 1824 and/or control logic 1816 is
included in interface circuit 1818.
[0151] Moreover, the circuits and components in electronic device
1800 may be implemented using any combination of analog and/or
digital circuitry, including: bipolar, PMOS and/or NMOS gates or
transistors. Furthermore, signals in these embodiments may include
digital signals that have approximately discrete values and/or
analog signals that have continuous values. Additionally,
components and circuits may be single-ended or differential, and
power supplies may be unipolar or bipolar.
[0152] An integrated circuit (which is sometimes referred to as a
`communication circuit`) may implement some or all of the
functionality of networking subsystem 1814. This integrated circuit
may include hardware and/or software mechanisms that are used for
transmitting wireless signals from electronic device 1800 and
receiving signals at electronic device 1800 from other electronic
devices. Aside from the mechanisms herein described, radios are
generally known in the art and hence are not described in detail.
In general, networking subsystem 1814 and/or the integrated circuit
can include any number of radios. Note that the radios in
multiple-radio embodiments function in a similar way to the
described single-radio embodiments.
[0153] In some embodiments, networking subsystem 1814 and/or the
integrated circuit include a configuration mechanism (such as one
or more hardware and/or software mechanisms) that configures the
radio(s) to transmit and/or receive on a given communication
channel (e.g., a given carrier frequency). For example, in some
embodiments, the configuration mechanism can be used to switch the
radio from monitoring and/or transmitting on a given communication
channel to monitoring and/or transmitting on a different
communication channel. (Note that `monitoring` as used herein
includes receiving signals from other electronic devices and
possibly performing one or more processing operations on the
received signals).
[0154] In some embodiments, an output of a process for designing
the integrated circuit, or a portion of the integrated circuit,
which includes one or more of the circuits described herein may be
a computer-readable medium such as, for example, a magnetic tape or
an optical or magnetic disk. The computer-readable medium may be
encoded with data structures or other information describing
circuitry that may be physically instantiated as the integrated
circuit or the portion of the integrated circuit. Although various
formats may be used for such encoding, these data structures are
commonly written in: Caltech Intermediate Format (CIF), Calma GDS
II Stream Format (GDSII) or Electronic Design Interchange Format
(EDIF). Those of skill in the art of integrated circuit design can
develop such data structures from schematic diagrams of the type
detailed above and the corresponding descriptions and encode the
data structures on the computer-readable medium. Those of skill in
the art of integrated circuit fabrication can use such encoded data
to fabricate integrated circuits that include one or more of the
circuits described herein.
[0155] While the preceding discussion used a Wi-Fi communication
protocol as an illustrative example, in other embodiments a wide
variety of communication protocols and, more generally, wireless
communication techniques may be used. Thus, the communication
technique may be used in a variety of network interfaces.
Furthermore, while some of the operations in the preceding
embodiments were implemented in hardware or software, in general
the operations in the preceding embodiments can be implemented in a
wide variety of configurations and architectures. Therefore, some
or all of the operations in the preceding embodiments may be
performed in hardware, in software or both. For example, at least
some of the operations in the communication technique may be
implemented using program module 1822, operating system 1824 (such
as a driver for interface circuit 1818) or in firmware in interface
circuit 1818. Alternatively or additionally, at least some of the
operations in the communication technique may be implemented in a
physical layer, such as hardware in interface circuit 1818. In some
embodiments, the communication technique is implemented, at least
in part, in a MAC layer and/or in a physical layer in interface
circuit 1818.
[0156] Furthermore, in general, the communication technique may be
used to facilitate scheduled channel access in time and/or
frequency in conjunction with multi-user multiple input multiple
output (MU-MIMO) and/or OFDMA.
[0157] In the preceding description, we refer to `some
embodiments.` Note that `some embodiments` describes a subset of
all of the possible embodiments, but does not always specify the
same subset of embodiments.
[0158] The foregoing description is intended to enable any person
skilled in the art to make and use the disclosure, and is provided
in the context of a particular application and its requirements.
Moreover, the foregoing descriptions of embodiments of the present
disclosure have been presented for purposes of illustration and
description only. They are not intended to be exhaustive or to
limit the present disclosure to the forms disclosed. Accordingly,
many modifications and variations will be apparent to practitioners
skilled in the art, and the general principles defined herein may
be applied to other embodiments and applications without departing
from the spirit and scope of the present disclosure. Additionally,
the discussion of the preceding embodiments is not intended to
limit the present disclosure. Thus, the present disclosure is not
intended to be limited to the embodiments shown, but is to be
accorded the widest scope consistent with the principles and
features disclosed herein.
* * * * *