U.S. patent application number 14/277613 was filed with the patent office on 2014-11-20 for access point response to ps-poll.
This patent application is currently assigned to QUALCOMM Incorporated. The applicant listed for this patent is QUALCOMM Incorporated. Invention is credited to James Simon Cho, Shu Du, Guido Robert Frederiks, Sandip HomChaudhuri, Arunkumar Jayaraman, Zhanfeng Jia, Alireza Raissinia, Jibing Wang.
Application Number | 20140341098 14/277613 |
Document ID | / |
Family ID | 51895715 |
Filed Date | 2014-11-20 |
United States Patent
Application |
20140341098 |
Kind Code |
A1 |
Cho; James Simon ; et
al. |
November 20, 2014 |
ACCESS POINT RESPONSE TO PS-POLL
Abstract
Methods, systems, and devices are described for power
conservation in a wireless communications system through efficient
transmissions and acknowledgements of information between an AP and
a station. The time between a determination by a station to enter a
power saving mode and entering network sleep mode by the station
may be reduced through a transmission, by an AP, of an MPDU to the
station successive to an SIFS after transmission of an
acknowledgement to the station of a PS-Poll frame from the station.
The time to enter a power saving mode by a station may also be
reduced through transmission of A-MPDUs in which a last MPDU of the
A-MPDU has an indicator bit cleared to indicate no additional data
is to be transmitted. An AP may prevent a retransmission of an MPDU
to the station in the absence of an acknowledgement from the
station, to further enhance efficiency.
Inventors: |
Cho; James Simon; (Mountain
View, CA) ; Jayaraman; Arunkumar; (San Jose, CA)
; Frederiks; Guido Robert; (Aptos, CA) ; Jia;
Zhanfeng; (Belmont, CA) ; Du; Shu; (Milpitas,
CA) ; Raissinia; Alireza; (Monte Sereno, CA) ;
Wang; Jibing; (San Diego, CA) ; HomChaudhuri;
Sandip; (San Jose, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM Incorporated |
San Diego |
CA |
US |
|
|
Assignee: |
QUALCOMM Incorporated
San Diego
CA
|
Family ID: |
51895715 |
Appl. No.: |
14/277613 |
Filed: |
May 14, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61823863 |
May 15, 2013 |
|
|
|
Current U.S.
Class: |
370/311 |
Current CPC
Class: |
H04W 52/0216 20130101;
Y02D 70/142 20180101; H04W 52/0206 20130101; Y02D 70/144 20180101;
H04L 1/08 20130101; Y02D 70/1262 20180101; Y02D 70/22 20180101;
Y02D 30/70 20200801; H04W 84/12 20130101; H04W 52/0238 20130101;
H04W 72/02 20130101; H04W 52/0235 20130101 |
Class at
Publication: |
370/311 |
International
Class: |
H04W 52/02 20060101
H04W052/02; H04L 1/08 20060101 H04L001/08 |
Claims
1. A method for wireless communications, comprising: receiving a
power save poll (PS-Poll) frame from a station; transmitting an
acknowledgement to the station that the PS-Poll frame is received
following a short interframe space (SIFS); and transmitting a media
access control (MAC) protocol data unit (MPDU) to the station
responsive to the PS-Poll frame successive to an SIFS after
transmission of the acknowledgement to the station.
2. The method of claim 1, further comprising: receiving an
acknowledgement from the station that the MPDU is received; and
assuming the station has gone to network sleep.
3. The method of claim 2, further comprising limiting a number of
retransmissions of the MPDU to the station in the absence of the
acknowledgement from the station that the MPDU is received.
4. The method of claim 3, further comprising: assuming that the
station has gone to network sleep following transmitting the
limited number of retransmissions.
5. The method of claim 1, wherein transmitting the MPDU comprises:
determining that more data is to be transmitted to the station than
is included in the MPDU; setting an indicator bit in the MPDU to
indicate that more data is to be transmitted to the station; and
assuming the station has gone to network sleep following
transmission of the MPDU.
6. The method of claim 5, wherein assuming the station has gone to
sleep comprises: receiving an acknowledgement from the station that
the MPDU is received; and assuming the station has gone to network
sleep.
7. The method of claim 5, further comprising: receiving a second
PS-Poll frame from the station; and transmitting a second MPDU to
the station responsive to the second PS-Poll frame including the
more data.
8. The method of claim 7, wherein transmitting the second MPDU
comprises: determining that no additional data is to be transmitted
to the station following transmission of the MPDU; setting an
indicator bit in the MPDU to indicate that no more data is to be
transmitted to the station; and assuming the station has gone to
network sleep following transmission of the MPDU.
9. The method of claim 1, wherein the MPDU comprises an aggregated
MPDU (A-MPDU) comprising a plurality of aggregated MPDUs, each of
the aggregated MPDUs comprising an indicator bit to indicate
whether more data is to be transmitted to the station.
10. The method of claim 9, further comprising: receiving a block
acknowledgement (BA) from the station that each MPDU of the A-MPDU
is successfully received; assuming the station has gone to network
sleep; receiving a second PS-Poll frame from the station; and
transmitting a second MPDU to the station with the indicator bit
cleared to indicate no additional data is to be transmitted.
11. The method of claim 1, wherein the MPDU comprises an aggregated
media access control protocol data unit (A-MPDU) comprising a
plurality of aggregated MPDUs to the station responsive to the
PS-Poll frame, the plurality of aggregated MPDUs comprising at
least a first MPDU and a last MPDU each comprising an indicator bit
to indicate whether more data is to be transmitted to the station,
and wherein the indicator bit of the first MPDU is set to indicate
more data and the indicator bit of the last MPDU is cleared to
indicate no additional data is to be transmitted.
12. The method of claim 11, wherein the acknowledgement to the
station is transmitted prior to transmitting the A-MPDU.
13. The method of claim 12, wherein the A-MPDU is transmitted
successive to an SIFS after transmission of the acknowledgement to
the station.
14. The method of claim 11, further comprising: receiving a block
acknowledgement (BA) from the station that the A-MPDU is received
and indicating that at least one MPDU of the A-MPDU was not
successfully received; and assuming the station has gone to network
sleep.
15. The method of claim 14, further comprising: receiving a second
PS-Poll frame from the station; and transmitting a second A-MPDU to
the station comprising at least one MPDU including data from the at
least one MPDU not successfully received.
16. The method of claim 14, wherein the BA comprises a starting
sequence number of MPDUs and a bitmap indicating successful
reception of a plurality of MPDUs sequenced prior to the starting
sequence number.
17. The method of claim 11, further comprising: determining that a
block acknowledgement (BA) is not received from the station;
determining that more data is to be transmitted to the station that
is included in the A-MPDU; adding at least one additional MPDU to
the A-MPDU to generate a second A-MPDU; and transmitting the second
A-MPDU to the station.
18. An apparatus for wireless communications, comprising: a
receiver configured to receive a power save poll (PS-Poll) frame
from a station; a transmitter configured to transmit an
acknowledgement to the station that the PS-Poll frame is received
following a short interframe space (SIFS), and to transmit a media
access control (MAC) protocol data unit (MPDU) to the station
responsive to the PS-Poll frame successive to an SIFS after
transmission of the acknowledgement to the station.
19. The apparatus of claim 18, wherein the receiver is further
configured to receive an acknowledgement from the station that the
MPDU is received, the apparatus further comprising: a power save
communicator configured to assume the station has gone to network
sleep following transmission of the MPDU.
20. The apparatus of claim 19, wherein the power save communicator
is further configured to limit a number of retransmissions of the
MPDU to the station in the absence of the acknowledgement from the
station that the MPDU is received.
21. The apparatus of claim 20, wherein the power save communicator
is further configured to assume the station has gone to network
sleep following the limited number of retransmissions.
22. The apparatus of claim 18, further comprising a power save
communicator configured to: determine that more data is to be
transmitted to the station than is included in the MPDU; and set an
indicator bit in the MPDU to indicate that more data is to be
transmitted to the station.
23. The apparatus of claim 22, wherein: the receiver is further
configured to receive a second PS-Poll frame from the station; and
the transmitter is further configured to transmit a second MPDU to
the station responsive to the second PS-Poll frame including the
more data.
24. The apparatus of claim 23, wherein the power save communicator
is further configured to: determine that no additional data is to
be transmitted to the station following transmission of the MPDU;
setting an indicator bit in the MPDU to indicate that no more data
is to be transmitted to the station; and assuming the station has
gone to network sleep following transmission of the MPDU.
25. The apparatus of claim 18, wherein the MPDU comprises an
aggregated media access control protocol data unit (A-MPDU)
comprising a plurality of aggregated MPDUs to the station
responsive to the PS-Poll frame, the plurality of aggregated MPDUs
comprising at least a first MPDU and a last MPDU each comprising an
indicator bit to indicate whether more data is to be transmitted to
the station, and wherein the indicator bit of the first MPDU is set
to indicate more data and the indicator bit of the last MPDU is
cleared to indicate no additional data is to be transmitted.
26. An apparatus for wireless communications, comprising: means for
receiving a power save poll (PS-Poll) frame from a station; means
for transmitting an acknowledgement to the station that the PS-Poll
frame is received following a short interframe space (SIFS); and
means for transmitting a media access control (MAC) protocol data
unit (MPDU) to the station responsive to the PS-Poll frame
successive to an SIFS after transmission of the acknowledgement to
the station.
27. The apparatus of claim 26, further comprising: means for
receiving an acknowledgement from the station that the MPDU is
received; and means for assuming the station has gone to network
sleep.
28. The apparatus of claim 26, wherein the means for transmitting
the MPDU is configured to: determine that more data is to be
transmitted to the station than is included in the MPDU; set an
indicator bit in the MPDU to indicate that more data is to be
transmitted to the station; and assume the station has gone to
network sleep following transmission of the MPDU.
29. The apparatus of claim 26, wherein the MPDU comprises an
aggregated media access control protocol data unit (A-MPDU)
comprising a plurality of aggregated MPDUs to the station
responsive to the PS-Poll frame, the plurality of aggregated MPDUs
comprising at least a first MPDU and a last MPDU each comprising an
indicator bit to indicate whether more data is to be transmitted to
the station, and wherein the indicator bit of the first MPDU is set
to indicate more data and the indicator bit of the last MPDU is
cleared to indicate no additional data is to be transmitted.
30. A computer program product for wireless communications, the
computer program product comprising a non-transitory
computer-readable medium storing instructions executable by a
processor to: receive a power save poll (PS-Poll) frame from a
station; transmit an acknowledgement to the station that the
PS-Poll frame is received following a short interframe space
(SIFS); and transmit a media access control (MAC) protocol data
unit (MPDU) to the station responsive to the PS-Poll frame
successive to an SIFS after transmission of the acknowledgement to
the station.
Description
CROSS REFERENCES
[0001] The present application for patent claims priority to U.S.
Provisional Patent Application No. 61/823,863 by Cho et al.,
entitled "SIFS Response to PS-Poll," filed May 15, 2013, assigned
to the assignee hereof, and expressly incorporated by reference
herein. The present application is related to copending Application
No. 133029U1 by Cho et al., entitled "ACCESS POINT RESPONSE TO
PS-POLL," assigned to the assignee hereof, and expressly
incorporated by reference herein. The present application is also
related to copending Application No. 133029U3, by Sun et al.,
entitled "ACCESS POINT-AIDED COEXISTENCE/CONCURRENCY AT MOBILE
DEVICES," assigned to the assignee hereof, and expressly
incorporated by reference herein.
BACKGROUND
[0002] Wireless communications networks are widely deployed to
provide various communication services such as voice, video, packet
data, messaging, broadcast, and the like. These wireless networks
may be multiple-access networks capable of supporting multiple
users by sharing the available network resources.
[0003] A wireless communications network may include a number of
network devices such as access points (APs) that can support
communication for a number of wireless devices. A wireless device
may communicate with a network device bi-directionally. For
example, in a wireless local area network (WLAN), a station (STA)
may communicate with an associated AP via downlink and uplink. The
downlink (or forward link) refers to the communication link from
the AP to the station, and the uplink (or reverse link) refers to
the communication link from the station to the AP.
[0004] In WLANs, there may be cases in which a station may desire
to enter a power saving mode in which transmissions between an AP
and station are reduced, allowing the station to power off a
component(s), such as radio components, and thereby reduce power
consumption. Existing power saving techniques may, in some cases,
result in relatively long periods of time between a determination
by a station to enter a power saving mode and the powering off of
related components, because of related network signaling to notify
and confirm power saving mode with an AP. Therefore, power
conservation techniques are desirable that are simple to implement
and have relatively short time periods between a determination to
enter a power save mode by a station and the station entering a
power conservation mode.
SUMMARY
[0005] Various methods, systems, devices, and apparatuses are
described for wireless communications that may provide efficient
transmissions and acknowledgments of information between an AP and
a station. The time between a determination by a station to enter a
power saving mode and entering network sleep mode by the station
may be reduced through a transmission, by an AP, of a media access
control (MAC) protocol data unit (MPDU) to the station successive
to a short interframe space (SIFS) after transmission of an
acknowledgment to the station of a PS-Poll frame from the station.
Transmission of the MPDU after the SIFS following the
acknowledgment may reduce the time associated with random backoffs
following an acknowledgment of the AP, and may reduce or eliminate
the time associated with queue delay, other traffic, or collisions
of traffic with another station(s). The time to enter a power
saving mode by a station may also be reduced through transmission
of aggregated MPDUs (A-MPDUs), with initial MPDUs of an A-MPDU
having an indicator bit set to indicate more data and a last MPDU
of the A-MPDU having its indicator bit cleared to indicate no
additional data is to be transmitted. Efficiencies may further be
enhanced through an AP preventing a retransmission of an MPDU to
the station in the absence of an acknowledgement from the station
that the MPDU is received.
[0006] According to an aspect of the disclosure, a method for
wireless communications. The method generally includes receiving a
power save poll (PS-Poll) frame by the access point from a station,
transmitting a media access control (MAC) protocol data unit (MPDU)
to the station responsive to the PS-Poll frame, determining if an
acknowledgment of the MPDU is received from the station, and
preventing a retransmission of the MPDU to the station in the
absence of the acknowledgement from the station that the MPDU is
received. In some examples, a data transmission rate for the
station may remain unadjusted in the absence of the acknowledgement
from the station that the MPDU is received. In other examples the
data transmission rate for the station may remain unadjusted in the
absence of the acknowledgement from the station that the MPDU is
received for a set number of retransmissions and may be adjusted
following the set number of retransmissions. Additionally or
alternatively, the access point may receive an acknowledgment from
the station to one of the MPDU retransmissions, and adjust the data
transmission rate for the station responsive to the MPDU
retransmission acknowledgement. Such an adjustment may include, for
example, updating a rate adaptation table responsive to the
unacknowledged MPDU transmission(s).
[0007] In some examples, the method may also include determining
that the acknowledgment is not received due to a channel condition
of a transmission channel, and adjusting the data transmission rate
for the station responsive to the channel condition. In some
examples, the access point may, additionally or alternatively,
assume that the station has gone to network sleep following
transmitting a limited number of retransmissions. In further
examples, the access point may transmit, prior to transmitting the
MPDU, an acknowledgment to the station that the PS-Poll frame is
received.
[0008] The method of claim 1, wherein the MPDU comprises an
aggregated media access control protocol data unit (A-MPDU)
comprising a plurality of aggregated MPDUs to the station
responsive to the PS-Poll frame, the plurality of aggregated MPDUs
comprising at least a first MPDU and a last MPDU each comprising an
indicator bit to indicate whether more data is to be transmitted to
the station, and wherein the indicator bit of the first MPDU is set
to indicate more data and the indicator bit of the last MPDU is
cleared to indicate no additional data is to be transmitted.
[0009] In some examples, the method may further include
transmitting, prior to transmitting the A-MPDU, an acknowledgment
to the station that the PS-Poll frame is received following a short
interframe space (SIFS). The A-MPDU may be transmitted successive
to an SIFS after transmission of the acknowledgment to the station.
In some examples, the method may include receiving a block
acknowledgment (BA) from the station that the A-MPDU is received
and indicating that an MPDU of the A-MPDU was not successfully
received; and assuming the station has gone to network sleep. The
method may further include receiving a second PS-Poll frame from
the station; and transmitting a second A-MPDU to the station
comprising at least one MPDU including data from the MPDU(s) not
successfully received. The BA may include a starting sequence
number of MPDUs and a bitmap indicating successful reception of a
plurality of MPDUs sequenced prior to the starting sequence
number.
[0010] In some examples, the method may include determining that a
block acknowledgment (BA) is not received from the station;
determining that additional data is to be transmitted to the
station that is included in the A-MPDU; adding at least one
additional MPDU to the A-MPDU to generate a second A-MPDU; and
transmitting the second A-MPDU to the station.
[0011] Another aspect of the disclosure provides another method for
wireless communications. The method generally includes receiving a
power save poll (PS-Poll) frame from a station, transmitting an
acknowledgment to the station that the PS-Poll frame is received
following a short interframe space (SIFS), and transmitting a media
access control (MAC) protocol data unit (MPDU) to the station
responsive to the PS-Poll frame successive to an SIFS after
transmission of the acknowledgment to the station. In some
examples, the access point may also receive an acknowledgment from
the station that the MPDU is received, and assume the station has
gone to network sleep. In some examples, the method may also
include limiting a number of retransmissions of the MPDU to the
station in the absence of the acknowledgement from the station that
the MPDU is received, or assuming that the station has gone to
network sleep following transmitting the limited number of
retransmissions.
[0012] In some examples, the AP may determine that more data is to
be transmitted to the station than is included in the MPDU, an
indicator bit may be set in the MPDU to indicate that more data is
to be transmitted to the station, and the AP may assume the station
has gone to network sleep following transmission of the MPDU. The
assuming may include, for example, receiving an acknowledgment from
the station that the MPDU is received, and assuming the station has
gone to network sleep. The access point may receive a second
PS-Poll frame from the station, and transmit a second MPDU to the
station responsive to the second PS-Poll including the more data.
In some examples, transmitting the second MPDU may include
determining that no additional data is to be transmitted to the
station following transmission of the MPDU, setting an indicator
bit in the MPDU to indicate that no more data is to be transmitted
to the station, and assuming the station has gone to network sleep
following transmission of the MPDU. The MPDU may include, for
example, an aggregated MPDU (A-MPDU) comprising a number of
aggregated MPDUs, each of the aggregated MPDUs having an indicator
bit to indicate whether more data is to be transmitted to the
station. The method may further include, receiving a block
acknowledgment (BA) from the station that each MPDU of the A-MPDU
is successfully received, assuming the station has gone to network
sleep, receiving a second PS-Poll frame from the station, and
transmitting a second MPDU to the station with the indicator bit
cleared to indicate no additional data is to be transmitted.
[0013] In some examples, the MPDU includes an aggregated media
access control protocol data unit (A-MPDU) comprising a plurality
of aggregated MPDUs to the station responsive to the PS-Poll frame,
the plurality of aggregated MPDUs comprising at least a first MPDU
and a last MPDU each comprising an indicator bit to indicate
whether more data is to be transmitted to the station, and wherein
the indicator bit of the first MPDU is set to indicate more data
and the indicator bit of the last MPDU is cleared to indicate no
additional data is to be transmitted. The acknowledgement to the
station may be transmitted prior to transmitting the A-MPDU. The
A-MPDU may be transmitted successive to an SIFS after transmission
of the acknowledgement to the station.
[0014] In some examples, a block acknowledgement (BA) may be
received from the station, the BA indicating that the A-MPDU is
received and that an MPDU of the A-MPDU was not successfully
received. It may then be assumed that the station has gone to
network sleep. In additional or alternative examples, a second
PS-Poll frame may be received from the station; and a second A-MPDU
may be transmitted to the station comprising at least one MPDU
including data from the MPDU(s) not successfully received. The BA
may include a starting sequence number of MPDUs and a bitmap
indicating successful reception of a plurality of MPDUs sequenced
prior to the starting sequence number.
[0015] In some examples, the method may further include determining
that a block acknowledgement (BA) is not received from the station;
determining that more data is to be transmitted to the station that
is included in the A-MPDU; adding at least one additional MPDU to
the A-MPDU to generate a second A-MPDU; and transmitting the second
A-MPDU to the station.
[0016] A further aspect of the disclosure provides another method
for wireless communications. The method generally includes
receiving a power save poll (PS-Poll) frame from a station, and
transmitting an aggregated media access control protocol data unit
(A-MPDU) that includes a number of aggregated MPDUs to the station
responsive to the PS-Poll frame. The number of aggregated MPDUs can
include at least a first MPDU and a last MPDU each comprising an
indicator bit to indicate whether more data is to be transmitted to
the station, and the indicator bit of the first MPDU is set to
indicate more data and the indicator bit of the last MPDU is
cleared to indicate no additional data is to be transmitted. The
method may also include, in some examples, transmitting, prior to
transmitting the A-MPDU, an acknowledgment to the station that the
PS-Poll frame is received following a short interframe space
(SIFS). The A-MPDU may be transmitted, for example, following an
SIFS after transmission of the acknowledgment to the station.
[0017] In some examples, the method may also include receiving a
block acknowledgment (BA) from the station that the A-MPDU is
received and indicating that an MPDU of the A-MPDU was not
successfully received, and assuming the station has gone to network
sleep. Following receipt of the BA, the method may also include
receiving a second PS-Poll frame from the station, and transmitting
a second A-MPDU to the station comprising at least one MPDU
including data from the MPDU(s) not successfully received. The BA
may include, for example, a starting sequence number of MPDUs and a
bitmap indicating successful reception of a plurality of MPDUs
sequenced prior to the starting sequence number. In some examples,
the method may also include determining that a BA is not received
from the station, determining that more data is to be transmitted
to the station that is included in the A-MPDU, adding at least one
additional MPDU to the A-MPDU to generate a second A-MPDU, and
transmitting the second A-MPDU to the station.
[0018] Another aspect of the disclosure provides an apparatus for
wireless communications. The apparatus generally includes means for
receiving a power save poll (PS-Poll) frame from a station, means
for transmitting a media access control (MAC) protocol data unit
(MPDU) to the station responsive to the PS-Poll frame; means for
determining if an acknowledgment of the MPDU is received from the
station, and means for preventing a retransmission of the MPDU to
the station in the absence of the acknowledgement from the station
that the MPDU is received.
[0019] Another aspect of the disclosure provides an apparatus for
wireless communications. The apparatus generally includes means for
receiving a power save poll (PS-Poll) frame from a station, means
for transmitting an acknowledgment to the station that the PS-Poll
frame is received following a short interframe space (SIFS), and
means for transmitting a media access control (MAC) protocol data
unit (MPDU) to the station responsive to the PS-Poll frame
successive to an SIFS after transmission of the acknowledgment to
the station.
[0020] Another aspect of the disclosure provides another apparatus
for wireless communications. The apparatus generally includes means
for receiving a power save poll (PS-Poll) frame from a station, and
means for transmitting an aggregated media access control protocol
data unit (A-MPDU) including a number of aggregated MPDUs to the
station responsive to the PS-Poll frame, the aggregated MPDUs
including at least a first MPDU and a last MPDU each having an
indicator bit to indicate whether more data is to be transmitted to
the station, and the indicator bit of the first MPDU set to
indicate more data and the indicator bit of the last MPDU cleared
to indicate no additional data is to be transmitted.
[0021] In a further aspect, the disclosure provides another
apparatus for wireless communications. The apparatus generally
includes a receiver module configured to receive a PS-Poll frame
from a station, a transmitter module configured to transmit a media
access control (MAC) protocol data unit (MPDU) to the station
responsive to the PS-Poll frame, and a power save communications
module configured to determine if an acknowledgment of the MPDU is
received from the station and prevent a retransmission of the MPDU
to the station in the absence of the acknowledgement from the
station that the MPDU is received.
[0022] In yet a further aspect, the disclosure provides another
apparatus for wireless communications. The apparatus generally
includes a receiver configured to receive a power save poll
(PS-Poll) frame from a station, and a transmitter configured to
transmit an acknowledgment to the station that the PS-Poll frame is
received following a short interframe space (SIFS), and to transmit
a media access control (MAC) protocol data unit (MPDU) to the
station responsive to the PS-Poll frame successive to an SIFS after
transmission of the acknowledgment to the station.
[0023] In still a further aspect, the disclosure provides another
apparatus for wireless communications. The apparatus generally
includes a receiver configured to receive a power save poll
(PS-Poll) frame from a station, and a transmitter configured to
transmit an aggregated media access control protocol data unit
(A-MPDU) including a number of aggregated MPDUs to the station
responsive to the PS-Poll frame, the number of aggregated MPDUs
including at least a first MPDU and a last MPDU each having an
indicator bit to indicate whether more data is to be transmitted to
the station, and wherein the indicator bit of the first MPDU is set
to indicate more data and the indicator bit of the last MPDU is
cleared to indicate no additional data is to be transmitted.
[0024] In another aspect, the disclosure provides a device for
wireless communications. The device generally includes a processor
and a memory in electronic communication with the processor. The
memory embodying instructions executable by the processor to
receive a power save poll (PS-Poll) frame from a station, transmit
a media access control (MAC) protocol data unit (MPDU) to the
station responsive to the PS-Poll frame, determine if an
acknowledgment of the MPDU is received from the station, and
prevent a retransmission of the MPDU to the station in the absence
of the acknowledgement from the station that the MPDU is
received.
[0025] Another aspect of the disclosure provides another device for
wireless communications. The device generally includes a processor
and a memory in electronic communication with the processor. The
memory embodying instructions executable by the processor to
receive a power save poll (PS-Poll) frame from a station, transmit
an acknowledgment to the station that the PS-Poll frame is received
following a short interframe space (SIFS), and transmit a media
access control (MAC) protocol data unit (MPDU) to the station
responsive to the PS-Poll frame successive to a SIFS after
transmission of the acknowledgment to the station.
[0026] Still a further aspect of the disclosure provides a device
for wireless communications. The device generally includes a
processor and a memory in electronic communication with the
processor. The memory embodying instructions executable by the
processor to receive a power save poll (PS-Poll) frame from a
station, and transmit an aggregated media access control protocol
data unit (A-MPDU) including a number of aggregated MPDUs to the
station responsive to the PS-Poll frame, the number of aggregated
MPDUs including at least a first MPDU and a last MPDU each
including an indicator bit to indicate whether more data is to be
transmitted to the station, and wherein the indicator bit of the
first MPDU is set to indicate more data and the indicator bit of
the last MPDU is cleared to indicate no additional data is to be
transmitted.
[0027] Another aspect of the disclosure provides a computer program
product for wireless communications. The computer program product
generally includes a non-transitory computer-readable medium
storing instructions executable by a processor to receive a power
save poll (PS-Poll) frame from a station, transmit a media access
control (MAC) protocol data unit (MPDU) to the station responsive
to the PS-Poll frame, determine if an acknowledgment of the MPDU is
received from the station, and prevent a retransmission of the MPDU
to the station in the absence of the acknowledgement from the
station that the MPDU is received.
[0028] Another aspect of the disclosure provides another computer
program product for wireless communications. The computer program
product generally includes a non-transitory computer-readable
medium storing instructions executable by a processor to receive a
power save poll (PS-Poll) frame from a station, transmit an
acknowledgment to the station that the PS-Poll frame is received
following a short interframe space (SIFS), and transmit a media
access control (MAC) protocol data unit (MPDU) to the station
responsive to the PS-Poll frame successive to an SIFS after
transmission of the acknowledgment to the station.
[0029] Still a further aspect of the disclosure provides another
computer program product for wireless communications. The computer
program product generally includes a non-transitory
computer-readable medium storing instructions executable by a
processor to receive a power save poll (PS-Poll) frame from a
station, and transmit an aggregated media access control protocol
data unit (A-MPDU) including a number of aggregated MPDUs to the
station responsive to the PS-Poll frame, the number of aggregated
MPDUs including at least a first MPDU and a last MPDU each
including an indicator bit to indicate whether more data is to be
transmitted to the station, and wherein the indicator bit of the
first MPDU is set to indicate more data and the indicator bit of
the last MPDU is cleared to indicate no additional data is to be
transmitted.
[0030] The foregoing has outlined rather broadly the features and
technical advantages of examples according to the disclosure in
order that the detailed description that follows may be better
understood. Additional features and advantages will be described
hereinafter. The conception and specific examples disclosed may be
readily utilized as a basis for modifying or designing other
structures for carrying out the same purposes of the present
disclosure. Such equivalent constructions do not depart from the
spirit and scope of the appended claims. Features which are
believed to be characteristic of the concepts disclosed herein,
both as to their organization and method of operation, together
with associated advantages will be better understood from the
following description when considered in connection with the
accompanying figures. Each of the figures is provided for the
purpose of illustration and description only, and not as a
definition of the limits of the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] A further understanding of the nature and advantages of the
present disclosure may be realized by reference to the following
drawings. In the appended figures, similar components or features
may have the same reference label. Further, various components of
the same type may be distinguished by following the reference label
by a dash and a second label that distinguishes among the similar
components. If only the first reference label is used in the
specification, the description is applicable to any one of the
similar components having the same first reference label
irrespective of the second reference label.
[0032] FIG. 1 shows a diagram that illustrates an example of a
wireless local area network (WLAN) that supports power conservation
modes according to various embodiments;
[0033] FIG. 2 shows a diagram that illustrates an example of a
frame exchange between an AP and a station entering a power save
mode according to various embodiments;
[0034] FIG. 3 shows a diagram that illustrates another example of
an exchange between an AP and a station entering a power save mode
according to various embodiments;
[0035] FIG. 4 shows a diagram that illustrates an example of
transmissions between an AP and a station entering a power save
mode according to various embodiments;
[0036] FIG. 5 shows a diagram that illustrates another example of
transmissions between an AP and a station entering a power save
mode according to various embodiments;
[0037] FIG. 6 shows a diagram that illustrates another example of
transmissions between an AP and a station entering a power save
mode according to various embodiments;
[0038] FIG. 7 shows a diagram that illustrates another example of
transmissions between an AP and a station entering a power save
mode according to various embodiments;
[0039] FIG. 8 shows a diagram that illustrates another example of
transmissions between an AP and a station entering a power save
mode according to various embodiments;
[0040] FIG. 9 is a flowchart of an example of operations related to
entering power save mode for a station according to various
embodiments;
[0041] FIG. 10 is a flowchart of an example of operations related
to entering power save mode for an AP according to various
embodiments;
[0042] FIG. 11 shows a block diagram that illustrates an example of
a power saving mode architecture according to various
embodiments;
[0043] FIG. 12 shows a block diagram that illustrates an example of
a station architecture according to various embodiments;
[0044] FIG. 13 shows a block diagram that illustrates an example of
an AP architecture according to various embodiments;
[0045] FIG. 14 is a flowchart of an example of a method for power
conservation in a wireless communication system according to
various embodiments;
[0046] FIG. 15 is a flowchart of an example of another method for
power conservation in a wireless communication system according to
various embodiments;
[0047] FIG. 16 is a flowchart of an example of yet another method
for power conservation in a wireless communication system according
to various embodiments;
[0048] FIGS. 17A-D show diagrams that illustrate examples of
coexisting communications at a mobile device;
[0049] FIG. 18 shows a diagram that illustrates an example of
transmissions between a station and an AP for taking into
consideration scheduling information of other coexisting Tx/Rx
activities on the station;
[0050] FIG. 19 shows a timing diagram that illustrates an approach
for deriving timing information related to coexisting/interfering
Tx/Rx activities on a station;
[0051] FIG. 20A shows a diagram that illustrates how a coexistence
station may be at a disadvantage when competing for WLAN medium
with a non-coexistence or regular station in the same BSS;
[0052] FIG. 20B shows a diagram that illustrates how adjusting the
size of an A-MPDU to the non-coexistence station(s) may improve
throughput for the coexistence station and fairness to the
coexistence station;
[0053] FIG. 21 shows a diagram that illustrates an example of
transmissions between a coexistence station and an AP and
transmissions between a non-coexistence or regular station and the
AP;
[0054] FIG. 22 shows a block diagram that illustrates an example of
a device that may be used to implement various embodiments for
dealing with coexistence interference;
[0055] FIG. 23 shows a diagram that illustrates a station that may
be used to implement various embodiments for dealing with
coexistence interference;
[0056] FIG. 24 shows a diagram that illustrates AP that may be used
to implement various embodiments for dealing with coexistence
interference;
[0057] FIG. 25 is a flowchart of an example of a method for dealing
with coexistence interference; and
[0058] FIG. 26 is a flowchart of an example of another method for
dealing with coexistence interference.
DETAILED DESCRIPTION
[0059] Described examples are directed to methods, systems,
devices, and apparatuses for power conservation in a wireless
communications system that may enhance power conservation through
efficient transmissions and acknowledgements of information between
an AP and a station. The time between a determination by a station
to enter a power saving mode and entering network sleep mode by the
station may be reduced through a transmission, by an AP, of a media
access control (MAC) protocol data unit (MPDU) to the station
successive to a short interframe space (SIFS) after transmission of
an acknowledgement to the station of a PS-Poll frame from the
station. Transmission of the MPDU after the SIFS following the
acknowledgement may reduce the time associated with random backoffs
following an acknowledgement of the AP, and may reduce or eliminate
the time associated with queue delay, other traffic, or collisions
of traffic with another station(s). The time to enter a power
saving mode by a station may also be reduced through transmission
of aggregated MPDUs (A-MPDUs), with initial MPDUs of an A-MPDU
having an indicator bit set to indicate more data and a last MPDU
of the A-MPDU having its indicator bit cleared to indicate no
additional data is to be transmitted. Efficiencies may further be
enhanced through an AP preventing a retransmission of an MPDU to
the station in the absence of an acknowledgement from the station
that the MPDU is received. In addition to power savings, examples
described may also provide, for example, a more efficient usage of
the overall wireless medium, thus enhancing medium resources
available for other devices, providing a higher throughput, lower
wait times for devices to access the medium, and may reduce the
amount of collisions in the medium.
[0060] The power conservation techniques presented herein are
generally described in connection with WLANs for simplicity. A WLAN
(or Wi-Fi network) may refer to a network that is based on the
protocols described in the various IEEE 802.11 standards (e.g.,
802.11a/g, 802.11n, 802.11ac, 802.11ah, etc.). The same or similar
techniques, however, may be used for various other wireless
communications systems such as cellular wireless systems,
peer-to-peer wireless communications, ad hoc networks, satellite
communications systems, and other systems. The terms "system" and
"network" may be used interchangeably.
[0061] Thus, the following description provides examples, and is
not limiting of the scope, applicability, or configuration set
forth in the claims. Changes may be made in the function and
arrangement of elements discussed without departing from the spirit
and scope of the disclosure. Various examples may omit, substitute,
or add various procedures or components as appropriate. For
instance, the methods described may be performed in an order
different from that described, and various steps may be added,
omitted, or combined. Also, features described with respect to
certain examples may be combined in other examples.
[0062] As used herein, the term "successive to" refers to a second
transmission that immediately follows a first transmission. For
example, an MPDU that is transmitted "successive to an SIFS after
transmission of an acknowledgement" means that the MPDU is
transmitted immediately following an SIFS period that immediately
follows the termination of the acknowledgement.
[0063] Referring first to FIG. 1, a WLAN 100 or Wi-Fi network is
shown that is configured to provide enhanced power conservation.
The WLAN 100 includes an AP 105 and multiple associated stations
115. In this example, there are shown seven (7) stations or STAs
115, which are identified as STA.sub.--1, STA.sub.--2, STA.sub.--3,
STA.sub.--4, STA.sub.--5, STA.sub.--6, and STA.sub.--7. The WLAN
100, however, may have more or fewer stations 115 than those shown
in FIG. 1 since the number shown is simply for illustrative
purposes. The AP 105 and the associated stations 115 may represent
a basic service set (BSS). The various stations 115 in the BSS are
able to communicate with one another through the AP 105. Also shown
is a coverage area 120 of the AP 105, which may represent a basic
service area (BSA) of the WLAN 100. Although not shown in FIG. 1,
the BSS associated with the WLAN 100 is typically connected to a
wired or wireless distribution system (DS) that allows multiple APs
to be connected in an extended service set.
[0064] The AP 105 is configured to communicate bi-directionally
with each of the stations 115 using transmissions 130. The
transmissions 130 may include downlink transmissions (e.g., beacon
frames) that are sent from the AP 105 to a station 115 as well as
uplink transmissions (e.g., acknowledgements or ACK frames) that
are sent from a station 115 to the AP 105. Typically, the AP 105 is
configured to broadcast its downlink transmissions to the stations
115 that are within the coverage area 120. In situations where a
station 115 does not expect to actively transmit or receive data,
it may be beneficial for the station 115 to power down certain of
its components, such as radio components, in order to reduce power
consumption of the station. Various wireless standards, such as the
802.11 standards, define a power-save mode for stations 115. In
power-save mode, a station 115 may choose to enter a network sleep
mode for a beacon interval(s)s, waking periodically to receive
beacon frames that include a delivery traffic indication message
(DTIM). In some implementations, a DTIM may be transmitted
periodically in beacon frames, such as, for example, every other
beacon frame, and a station 115 in network sleep mode may awaken to
receive every other beacon frame but otherwise remain asleep and
may thereby reduce power consumption. To initiate a power-save
mode, a station 115 may transmit a notification to the AP 105, so
that the AP 105 will know how to handle data traffic destined for
the station 115. In some examples, the AP 105 and a station of the
stations 115 may be configured to implement communications related
to entry of a power save mode by the station.
[0065] With reference now to FIG. 2, an example 200 of
transmissions between a station and an AP, such as between a
station 115 and AP 105 of FIG. 1, according to traditional power
saving mode techniques is described. In this example, a station at
some point determines that it should enter into a power save mode.
Such a determination may be made, for example, based on a state of
a transmit data queue of the station, recent activity of the
station, or power saving preferences set for the station, to name
but a few examples. After the station has entered power save mode,
it may determine that there is data pending for it at the AP. Such
a determination may be based on, for example, a "TIM bit" which may
be set in the beacon sent out by the AP. In order to retrieve that
data, but still remaining in a Wi-Fi protocol based power save
state, the station may transmit a power-save polling (PS-Poll)
frame 205 to the AP. The AP, following a short interframe space
(SIFS) 210 may transmit an acknowledgement 215 that acknowledges
the receipt of the PS-Poll frame. Following a DCF interframe space
(DIFS) and a random backoff (RBO) 220, the AP may transmit a single
MPDU 225 in response to the PS-Poll frame 205. Following an SIFS
230, the station may transmit an acknowledgement 235 that the MPDU
225 was received.
[0066] At this point, the AP assumes that the station has gone back
into a network sleep mode, and the station may go into network
sleep mode. According to various implementations, the duration of
the DIFS and RBO on average is approximately 110 .mu.sec.
Additionally, other factors may also cause delays in a station
entering network sleep mode. For example, queue delays within the
AP may result in a delay of the transmission of MPDU 225 by the AP,
and reception of MPDU 225 by the STA. Such a queue delay may occur,
for example, when another station receives an MPDU or an aggregated
MPDU (A-MPDU) from the AP, which was queued to be transmitted
before the MPDU 225. Such a queue delay may result in a delayed
entry by the station into network sleep mode, and thus result in
increased power consumption relative to a case that experiences no
queue delay. Another factor that may delay a station from entering
network sleep mode is traffic from another station that may be
transmitted following lower RBO. The AP would then be delayed in
transmitting MPDU 225, which would in turn delay the station from
entering network sleep mode. A further factor that may delay a
station from entering network sleep mode is a collision between the
AP transmitted MPDU 225 and a transmission of another station. Such
a situation results in a retransmission of the MPDU 225 following
an increased RBO, potentially with a reduced data rate. Thus, such
a situation may also delay the station from entering network sleep
mode.
[0067] With reference now to FIG. 3, an example 300 of
transmissions between a station and an AP, such as between a
station 115 and AP 105 of FIG. 1, according to various examples is
described. In this example, a station makes a determination to
enter into a power save mode. As mentioned above, such a
determination may be made based on a number of factors at the
station. After the station has entered power save mode, it may
determine that there is data pending for it at the AP, similarly as
described above with respect to FIG. 2. In order to retrieve that
data while maintaining a power save state, the station may transmit
a PS-Poll frame 205-a to the AP. The AP, following SIFS 210-a may
transmit an acknowledgement 215-a that acknowledges the receipt of
the PS-Poll frame, also similarly as described with respect to FIG.
2. Following a DIFS and RBO 220-a, the AP may transmit a single
MPDU 225-a in response to the PS-Poll frame 205-a. Following an
SIFS 230-a, the station may transmit an acknowledgement 305 that
the MPDU 225-a was received.
[0068] Circumstances may arise, however, which may prevent the
acknowledgement 305 from being received at the AP. For example,
interference may result in the AP being unable to properly receive
the acknowledgement 305. The station, however, having sent the
acknowledgement 305 may enter into network sleep mode. The AP,
following a timeout period 315, may retransmit MPDU 225-a. The
station, having entered network sleep mode, does not receive the
retransmitted MPDU 225-a, and the AP thus does not receive an
acknowledgement again. The AP, in this example, retransmits MPDU
225-a after period 310, which is an increased backoff period with
respect to period 310. According to the example of FIG. 3, the
station again would not transmit an acknowledgement, resulting in
the AP again retransmitting the MPDU 225-a following period 320
which has an increased backoff period as compared to period
315.
[0069] According to some examples, the AP may discontinue sending
retransmissions of the MPDU following a limited number of MPDUs
after the PS-Poll frame. Such a limit on retransmissions may save
some network and AP resources, as compared to implementations where
retransmissions are attempted until an acknowledgement is received.
Additionally, according to some examples, a data transmission rate
for the station may remain unadjusted in the absence of the
acknowledgement from the station that the MPDU is received, based
on the assumption that the station may be in sleep mode. In some
other cases, the AP may transmit at unadjusted data rate for a
limited number of attempts, and then adjust the data rate for a
subsequent transmission(s) of an MPDU. In some examples, the AP and
station may communicate on a busy or noisy channel, which may
result in the station being unable to receive transmissions at the
unchanged rate, and it may be determined that the lack of an
acknowledgement is a result of the channel conditions or is a
result of a collision with another station(s) communicating with
the AP. In such cases, the retransmission of MPDU 225-a may be
performed using an adjusted data rate or with a different backoff
period applied. Adjusting the data transmission rate may be
accomplished, for example, through an update to a rate adaptation
table at the AP.
[0070] With reference now to FIG. 4, an example 400 of
transmissions between a station and an AP, such as between a
station 115 and AP 105 of FIG. 1, according to power saving
techniques of various examples is described. In this example, a
station determines that it should enter into a power save mode.
Such a determination may be made as discussed above, according to
factor(s) at the station. After the station has entered power save
mode, it may determine that there is data pending for it at the AP,
similarly as described above with respect to FIG. 2. In order to
retrieve that data while maintaining a power save state, the
station may transmit a PS-Poll frame 405 to the AP. The AP,
following SIFS 410 may transmit an acknowledgement 415 that
acknowledges the receipt of the PS-Poll frame. In the example of
FIG. 4, instead of waiting for a DCF interframe space (DIFS) and a
random backoff (RBO) periods, the AP waits only for an SIFS 420,
and transmits MPDU 425. That is, the AP transmits MPDU 425
successive to SIFS 420 without waiting for the DIFS and RBO times
after the transmission of the acknowledgement 415 to the station.
Following another SIFS 430, the station may transmit an
acknowledgement 435 that the MPDU 425 was received. At this point,
the AP assumes that the station has gone to network sleep mode, and
the station may go into network sleep mode. During the time that
the AP is transmitting acknowledgement 415, a module of the AP may
prepare the MPDU 425 for transmission such that the MPDU 425 is set
to be transmitted successive to SIFS 420. In such a manner, the
time for the station to enter network sleep is reduced, thus
enhancing power savings at the station. In cases where the DIFS and
RBO times are reduced, the station may enter network sleep mode,
according to some examples, approximately 100 .mu.s sooner.
However, in cases where additional delay may be present, such as
queue delays, other traffic delays, and/or collision delays, the
time for the station to enter network sleep may be more
significantly reduced, thus further enhancing power savings.
[0071] In some examples, an AP may have additional data in its
buffered data queue to be transmitted to the station than may be
transmitted in a single MPDU. With reference now to FIG. 5, another
example 500 of transmissions between a station and an AP, such as
between a station 115 and AP 105 of FIG. 1, according to power
saving techniques of various examples is described. In this
example, a station determines that it should enter into a power
save mode. Such a determination may be made as discussed above,
according to factor(s) at the station. After the station has
entered power save mode, it may determine that there is data
pending for it at the AP, similarly as described above with respect
to FIG. 2. In order to retrieve that data while maintaining a power
save state, the station may transmit a PS-Poll frame 505 to the AP.
The AP, following SIFS 510 may transmit an acknowledgement 515 that
acknowledges the receipt of the PS-Poll frame. In the example of
FIG. 5, the AP waits only for the SIFS 520, and transmits MPDU 525.
The MPDU 525 may include an indicator bit to indicate that more
data is to be transmitted to the station following the transmission
of the MPDU 525. Such an indicator bit may be referred to as a
"more bit" and may be set or cleared based on the status of the
buffered data queue at the AP.
[0072] Following an SIFS 530, the station may transmit an
acknowledgement 535 that the MPDU 525 was received. At this point,
the AP assumes that the station has gone to network sleep mode,
although the station, based on the more bit of the MPDU 525, may
not enter into sleep mode. In the example of FIG. 5, the station,
following period 540, transmits a second PS-Poll frame 545. The AP,
following SIFS 550 may transmit an acknowledgement 555 that
acknowledges the receipt of the second PS-Poll frame 545. The AP
again waits only for the SIFS 560, and transmits MPDU 565. If the
buffered data queue at the AP does not include any additional data
for the station, the more bit of MPDU 565 may be cleared. Following
an SIFS 570, the station may transmit an acknowledgement 575 that
the MPDU 565 was received. At this point, the AP assumes that the
station has gone to network sleep mode, and the station may go into
network sleep mode.
[0073] In some examples, rather than transmitting a single MPDU, an
AP may transmit an aggregated MPDU (A-MPDU). Such an A-MPDU may
include multiple MPDUs transmitted sequentially by the AP. With
reference now to FIG. 6, another example 600 of transmissions
between a station and an AP, such as between a station 115 and AP
105 of FIG. 1, according to power saving techniques of various
examples is described. In this example, a station determines that
it should enter into a power save mode. Such a determination may be
made as discussed above, according to factor(s) at the station.
After the station has entered power save mode, it may determine
that there is data pending for it at the AP, similarly as described
above with respect to FIG. 2. In order to retrieve that data while
maintaining a power save state, the station may transmit a PS-Poll
frame 605 to the AP. The AP, following an SIFS 610 may transmit an
acknowledgement 615 that acknowledges the receipt of the PS-Poll
frame. In the example of FIG. 6, the AP waits only for the SIFS
620, and transmits an A-MPDU 625. The A-MPDU 625 may include a
number of MPDUs 630, 635, 640 transmitted sequentially from the AP.
In the example of FIG. 6, the first two MPDUs 630, 635 of A-MPDU
625 have a more bit that is set, and the last MPDU 640 has a more
bit which is cleared to indicate that no more data is to be
transmitted by the AP to the station following the transmission of
the A-MPDU 625. In other examples, all of the more bits of A-MPDU
625 may be set to indicate that the buffered data queue at the AP
still contains additional data, which the AP could send to the STA
when the STA request it to do so, with, for example, a PS-POLL
frame.
[0074] Following an SIFS 645, the station may transmit a block
acknowledgement (BA) 650 indicating which MPDUs 630, 635, 640 of
A-MPDU 625 are properly received. Such a BA 650 may include,
according to some implementations, a starting MPDU sequence number
and a bitmap of a predefined number of prior sequence numbers, with
bits of the bitmap set or cleared to indicate which sequence
numbers have been properly received at the station. In the example
of FIG. 6, the BA 650 may indicate that MPDU 635 was not received.
At this point, the AP assumes that the station has gone to network
sleep mode, although the station, based on a status of its receive
queue indicating that MPDU 635 was not properly received, may not
enter into sleep mode. In the example of FIG. 6, the station,
following period 655, transmits a second PS-Poll frame 660. The AP,
following SIFS 665 may transmit an acknowledgement 670 that
acknowledges the receipt of the second PS-Poll frame 660. The AP
again waits only for the SIFS 675, and transmits MPDU 680. MPDU 680
may contain data initially attempted to be transmitted in MPDU 635.
If the buffered data queue at the AP does not include any
additional data for the station, the more bit of MPDU 680 may not
be set. Following an SIFS 685, the station may transmit an
acknowledgement 690 that the MPDU 680 was received. At this point,
the AP assumes that the station has gone to network sleep mode, and
the station may go into network sleep mode knowing that there is no
more data pending at the AP.
[0075] In some cases, the AP may not properly receive a BA from a
station, and may retransmit an A-MPDU following a random backoff
period. Similarly as discussed above with respect to FIG. 3, if,
after a limited number of re-transmits, no BA is received the AP
may in some examples assume that the station was asleep and makes
no change to the rate table. In some examples, however, additional
data may be received at the AP for transmission to the station.
According to some examples, additional MPDUs may be added to a
re-transmitted A-MPDU. With reference now to FIG. 7, an example 700
of retransmissions between a station and an AP that may include
additional MPDUs is described. Such transmissions may be between,
for example, a station 115 and AP 105 of FIG. 1. In this example, a
station initially determines that it should enter into a power save
mode. After the station has entered power save mode, it may
determine that there is data pending for it at the AP, similarly as
described above with respect to FIG. 2. In order to retrieve that
data while maintaining a power save state, the station may transmit
a PS-Poll frame 705 to the AP. The AP, following an SIFS 710 may
transmit an acknowledgement 715 that acknowledges the receipt of
the PS-Poll frame. In the example of FIG. 7, the AP waits only for
the SIFS 720, and transmits an A-MPDU 725. The A-MPDU 725 may
include a number of MPDUs 730, 735, 740 transmitted sequentially
from the AP. In the example of FIG. 7, the first two MPDUs 730, 735
of A-MPDU 725 have a more bit that is set, and the last MPDU 740
has a more bit this is cleared, to indicate that no more data is to
be transmitted to the station following the transmission of the
A-MPDU 725.
[0076] Following an SIFS 745, the station may transmit a BA 750
indicating which MPDUs 730, 735, 740 of A-MPDU 725 are properly
received. In the example of FIG. 7, the BA 750 may indicate that
MPDU 735 was not received. Circumstances may arise, however, which
may prevent the BA 750 from being received at the AP. For example,
interference may result in the AP being unable to properly receive
the BA 750. The AP, in the example of FIG. 7, may have received
additional data for the station. In such a case, the AP, following
a timeout period 755, may transmit A-MPDU 760. The A-MPDU 760 may
include retransmissions of MPDUs 730, 735, and 740 transmitted
sequentially from the AP, as well as MPDU 765, which includes the
additional data received at the AP. In other examples, BA 750 may
be properly received by the AP, but the station may send another
PS-Poll frame to the AP in order to retrieve the missing frame as
indicated by the BA, at which point the AP may add MPDU 765 in the
subsequent A-MPDU. In the example of FIG. 7, the first three MPDUs
730, 735, and 740 of A-MPDU 760 have a more bit that is set, and
the last MPDU 765 has a more bit this is cleared, indicate that
more data is to be transmitted to the station following the
transmission of the A-MPDU 760. Following an SIFS 770, the station
may transmit a BA 775 that the A-MPDU 760 was received. At this
point, the AP assumes that the station has gone to network sleep
mode, and the station may go into network sleep mode. In some
cases, the BA 775 may indicate that one of MPDUs 730, 735, 740, and
765 were not properly received, at which point the station may
transmit another PS-Poll frame in a similar manner as discussed
above with respect to FIG. 6.
[0077] In some implementations, a station may not be configured to
recognize that different MPDUs in an A-MPDU may contain different
values for more bits. In some examples, an AP may recognize that
the station does not have such capability, and may always set the
more bits in an A-MPDU to the same value. With reference now to
FIG. 8, another example 800 of A-MPDU transmissions between a
station and an AP, such as between a station 115 and AP 105 of FIG.
1, according to power saving techniques of various examples is
described. In this example, a station determines that it should
enter into a power save mode. After the station has entered power
save mode, it may determine that there is data pending for it at
the AP, similarly as described above with respect to FIG. 2. In
order to retrieve that data while maintaining a power save state,
the station may transmit a PS-Poll frame 805 to the AP. The AP,
following an SIFS 810 may transmit an acknowledgement 815 that
acknowledges the receipt of the PS-Poll frame. In the example of
FIG. 8, the AP waits only for the SIFS 820, and transmits an A-MPDU
825. The A-MPDU 825 may include a number of MPDUs 830, 835, 840
transmitted sequentially from the AP. In the example of FIG. 8, the
buffered data queue of AP may be empty following the transmission
of MPDU 840, but the AP may recognize that the station is not
configured to recognize different values of more bits in A-MPDU
825. Thus, each of the MPDUs 830, 835 and 840 of A-MPDU 825 has a
more bit that is set. Following an SIFS 845, the station may
transmit a BA 850 indicating that all MPDUs 830, 835, 840 of A-MPDU
825 are properly received. At this point, the AP assumes that the
station has gone to network sleep mode, although the station, based
on the value of the more bits of A-MPDU 825, may not enter into
sleep mode. In the example of FIG. 8, the station, following period
855, transmits a second PS-Poll frame 860. The AP, following SIFS
865 may transmit an acknowledgement 870 that acknowledges the
receipt of the second PS-Poll frame 860. The AP again waits only
for the SIFS 875, and transmits a null data frame 880 having a more
bit that is not set. Following an SIFS 885, the station may
transmit an acknowledgement 890 that the null data frame 880 was
received. At this point, the AP assumes that the station has gone
to network sleep mode, and the station may go into network sleep
mode.
[0078] With reference now to FIG. 9, a flow diagram of a method 900
for power conservation at a station is discussed in accordance with
various examples. The method 900 may be implemented using, for
example, the stations 115 of FIG. 1. At block 905, the station
transmits a PS-Poll frame. At block 910, the station determines if
an acknowledgement of the PS-Poll frame is received. If an
acknowledgement is not received, the station may transmit the
PS-Poll frame again, as indicated at block 905. If the station does
receive an acknowledgement, the station then determines if an MPDU
or A-MPDU is received. If an MPDU or A-MPDU is not received within
a timeout period, the station may transmit another PS-Poll frame,
as indicated at block 905, or in some examples may simply enter
network sleep mode. If an MPDU or A-MPDU is received at block 915,
the station determines an ACK policy, which can be ACK or BA,
according to block 920. For a single MPDU, this is typically ACK,
and for A-MPDU this is typically BA, but not always. In the case of
the acknowledgement policy being an ACK policy, an acknowledgement
may be transmitted, according to block 925. In the case of a BA
policy, the station may transmit a BA, according to block 930. At
block 935, the station determines if the re-order queue at the
station is empty. If the re-order queue is not empty, operations
continue at block 905. If the re-order queue is empty, the station
determines if an MPDU more bit was set in the received MPDU or more
bit was set in the last received MPDU of the A-MPDU, as indicated
at block 940. If the more bit was set, operations may continue at
block 905. Similarly, as discussed above, in some configurations, a
station may be able to identify if a more bit is set or cleared in
different MPDUs of an A-MPDU. If it is determined that the more bit
is not set, the station enters network sleep mode, as indicated at
block 945.
[0079] Turning now to FIG. 10, a flow diagram of a method 1000 for
power conservation at an AP is discussed in accordance with various
examples. The method 1000 may be implemented using, for example,
the APs 105 of FIG. 1. At block 1005, the AP receives a PS-Poll
frame. At block 1010, the AP transmits an acknowledgement of the
PS-Poll frame. The AP then determines, at block 1015, whether the
buffered data queue for the station is empty. If the buffered data
queue is empty, the AP transmits a null frame with the more bit
cleared following an SIFS period after transmission of the
acknowledgement, as indicated at block 1020. At block 1025, the AP
determines if an acknowledgement is received. If an acknowledgement
is not received, the AP station may retransmit, at block 1030, the
null frame a limited number of times, similarly as discussed above.
If an acknowledgement is received at block 1025, the AP may assume
that the station is asleep, as indicated at block 1035. If, at
block 1015, the buffered data queue is not empty, the AP, at block
1040, determines if more data is present after an A-MPDU is
transmitted to the station. If more data is present, the AP may
transmit an A-MPDU with more bits set for each MPDU of the A-MPDU,
as indicated at block 1045. In some examples, the AP may also
determine that the station may not be configured to distinguish
that different MPDUs of an A-MPDU may have different values for a
more bit, and may set all of the more bits of the MPDUs of the
A-MPDU. If it is determined that the buffered data queue will be
empty following transmission of an A-MPDU, the AP may transmit an
A-MPDU with the more bit of the last MPDU cleared, as indicated at
block 1050. As noted above, in cases where a station may not
recognize different more bit values in an A-MPDU, block 1055 may be
skipped. At block 1055, it is determined whether a BA is received
for all of the MPDUs. If a BA is received, the AP may assume that
the station is asleep, according to block 1035. If the BA is not
received, the AP may retransmit the A-MPDU a limited number of
times, as indicated at block 1060. Retransmissions may be performed
in a similar manner as discussed above, for example.
[0080] With reference now to FIG. 11, a block diagram illustrates a
device 1100 that may be used in power conservation of various
examples. The device 1100 may be an example of various aspects of
the APs 105 or stations 115 described with reference to FIG. 1. The
device 1100, or portions of it, may also be a processor. The device
1100 may include a receiver 1110, a power save mode module 1115,
and/or a transmitter 1120. Each of these components may be in
communication with each other. The device 1100, through the
receiver 1110, the power save mode module 1115, and/or the
transmitter 1120, may be configured to transmit and receive
transmissions for entering a power save mode, similarly as
discussed above with respect to FIGS. 2-10.
[0081] Turning to FIG. 12, a diagram 1200 is shown that illustrates
a station 115-b configured for power conservation according to
various examples. The station 115-b may have various other
configurations and may be included or be part of a personal
computer (e.g., laptop computer, netbook computer, tablet computer,
etc.), a cellular telephone, a PDA, a digital video recorder (DVR),
an internet appliance, a gaming console, an e-readers, etc. The
station 115-b may have an internal power supply (not shown), such
as a small battery, to facilitate mobile operation. The station
115-b may be an example of the stations 115 of FIG. 1.
[0082] The station 115-b may include a processor 1205, a memory
1210, a transceiver 1225, antennas 1230, and a power manager 1220.
The power manager 1220 may be an example of the power save mode
module 1115 of FIG. 11. Each of these components may be in
communication with each other, directly or indirectly, over a
bus(es) for example.
[0083] The memory 1210 may include random access memory (RAM) and
read-only memory (ROM). The memory 1210 may store
computer-readable, computer-executable software (SW) code 1215
containing instructions that are configured to, when executed,
cause the processor 1205 to perform various functions described
herein for power conservation. Alternatively, the software code
1215 may not be directly executable by the processor 1205 but be
configured to cause the computer (e.g., when compiled and executed)
to perform functions described herein.
[0084] The processor 1205 may include an intelligent hardware
device, e.g., a central processing unit (CPU), a microcontroller,
an application-specific integrated circuit (ASIC), etc. The
processor 1205 may process information received through the
transceiver 1225 and/or to be sent to the transceiver 1225 for
transmission through the antennas 1230. The processor 1205 may
handle, alone or in connection with the power manager 1220, various
aspects for entering into a network sleep mode.
[0085] The transceiver 1225 may be configured to communicate
bi-directionally with APs 105 in FIG. 1. The transceiver 1225 may
be implemented as a transmitter(s) and a separate receiver(s). The
transceiver 1225 may include a modem configured to modulate packets
and provide the modulated packets to the antennas 1230 for
transmission, and to demodulate packets received from the antennas
1230. While the station 115-b may include a single antenna, there
may be examples in which the station 115-b may include multiple
antennas 1230.
[0086] The components of the station 115-b may be configured to
implement aspects discussed above with respect to FIGS. 2-10, and
those aspects may not be repeated here for the sake of brevity.
Moreover, the components of the station 115-b may be configured to
implement aspects discussed below with respect to FIGS. 14-16, and
those aspects may not be repeated here also for the sake of
brevity.
[0087] Turning to FIG. 13, a diagram 1300 is shown that illustrates
an access point or AP 105-b configured for power conservation
according to various examples. In some examples, the AP 105-b may
be an example of the APs 105 of FIG. 1. The AP 105-b may include a
processor 1310, a memory 1320, a transceiver 1330, antennas 1340,
and a power save communicator 1345. The power save communicator
1345 may be an example of the power save mode module 1115 of FIG.
11. In some examples, the AP 105-b may also include one or both of
an AP communicator 1380 and a network communicator 1385. Each of
these components may be in communication with each other, directly
or indirectly, over a bus(es) 1315.
[0088] The memory 1320 may include RAM and ROM. The memory 1320 may
also store computer-readable, computer-executable software (SW)
code 1325 containing instructions that are configured to, when
executed, cause the processor 1310 to perform various functions
described herein for entry of a power save mode by a station, for
example. Alternatively, the software code 1325 may not be directly
executable by the processor 1310 but be configured to cause the
computer, e.g., when compiled and executed, to perform functions
described herein.
[0089] The processor 1310 may include an intelligent hardware
device, e.g., a CPU, a microcontroller, an ASIC, etc. The processor
1310 may process information received through the transceiver 1330,
the AP communicator 1380, and/or the network communicator 1385. The
processor 1310 may also process information to be sent to the
transceiver 1330 for transmission through the antennas 1340, to the
AP communicator 1380, and/or to the network communicator 1385. The
processor 1310 may handle, alone or in connection with power save
communicator 1345, various aspects related to power save mode
communications as discussed above.
[0090] The transceiver 1330 may include a modem configured to
modulate packets and provide the modulated packets to the antennas
1340 for transmission, and to demodulate packets received from the
antennas 1340. The transceiver 1330 may be implemented as a
transmitter(s) and a separate receiver(s). The transceiver 1330 may
be configured to communicate bi-directionally, via the antennas
1340, with a station(s) 115 as illustrated in FIG. 1 or FIG. 12,
for example. The AP 105-b may typically include multiple antennas
1340 (e.g., an antenna array). The AP 105-b may communicate with a
core network 1305 through the network communicator 1385. The AP
105-b may communicate with other APs, such as the access point
105-i and the access point 105-j, using an AP communicator
1380.
[0091] According to the architecture of FIG. 13, the AP 105-b may
further include a communications manager 1350. The communications
manager 1350 may manage communications with stations and/or other
devices as illustrated in the WLAN 100 of FIG. 1, for example. The
communications manager 1350 may be in communication with some or
all of the other components of the AP 105-b via the bus or buses
1315. Alternatively, functionality of the communications manager
1350 may be implemented as a component of the transceiver 1330, as
a computer program product, and/or as a controller element(s) of
the processor 1310.
[0092] The components of the AP 105-b may be configured to
implement aspects discussed above with respect to FIGS. 2-10, and
those aspects may not be repeated here for the sake of brevity.
Moreover, the components of the AP 105-b may be configured to
implement aspects discussed below with respect to FIGS. 14-16 and
those aspects may not be repeated here also for the sake of
brevity.
[0093] Turning next to FIG. 14, a flow diagram is described for a
method 1400 for power conservation in accordance with various
examples. The method 1400 may be implemented using, for example,
the APs 105 of FIG. 1 or 13; or the device 1100 of FIG. 11, for
example. At block 1405, the AP may receive a power save poll
(PS-Poll) frame from a station. At block 1410, the AP may transmit
a MPDU to the station responsive to the PS-Poll frame. At block
1415, the AP determines if an acknowledgement of the MPDU is
received from the station. Finally, the AP may prevent a
retransmission of the MPDU to the station in the absence of the
acknowledgement from the station that the MPDU is received.
[0094] Turning next to FIG. 15, a flow diagram is described for a
method 1500 for power conservation in accordance with various
examples. The method 1500 may be implemented using, for example,
the APs 105 of FIG. 1 or 13; or the device 1100 of FIG. 11, for
example. At block 1505, the AP receives a power save poll (PS-Poll)
frame from a station. The AP then may transmit an acknowledgement
to the station that the PS-Poll frame is received following a short
interframe space (SIFS), according to block 1510. At block 1515,
the AP transmits an MPDU to the station responsive to the PS-Poll
frame successive to an SIFS after transmission of the
acknowledgement to the station.
[0095] Turning next to FIG. 16, a flow diagram is described for a
method 1600 for power conservation in accordance with various
examples. The method 1600 may be implemented using, for example,
the APs 105 of FIG. 1 or 13; or the device 1100 of FIG. 11, for
example. At block 1605, the AP receives a power save poll (PS-Poll)
frame from a station. In response to the PS-Poll frame, the AP, at
block 1610, transmits an A-MPDU comprising a plurality of
aggregated MPDUs to the station, the plurality of aggregated MPDUs
comprising a first MPDU and a last MPDU each comprising an
indicator bit to indicate that more data is to be transmitted to
the station, and wherein the indicator bit of the first MPDU is set
to indicate more data and the indicator bit of the last MPDU is
cleared to indicate no additional data is to be transmitted.
[0096] According to another aspect of this disclosure, described
examples are directed to methods, systems, devices, and apparatuses
to enable a WLAN access point (AP) to schedule packet transmissions
to (or from) a mobile device taking into consideration the schedule
of various other coexisting transmission/reception (Tx/Rx)
activities on the mobile device. Various embodiments may increase
throughput at the mobile device. Various embodiments also may
benefit other stations associated with the same AP.
[0097] Tx/Rx activities coexisting with WLAN communications on the
mobile device may include, for example, Long Term Evolution (LTE)
and Bluetooth (BT). Additionally or alternatively, the coexisting
Tx/Rx activities may include WLAN communications (e.g., Wi-Fi
concurrency), such as when the mobile device accesses the Internet
via the AP and concurrently communicates with another device, for
example, in a peer-to-peer (P2P) network.
[0098] In one example, a WLAN AP may learn interference information
(e.g., schedule, timing, etc.) from a coexisting radio at the
mobile device (e.g., station). The AP may learn the interference
information from the mobile device explicitly reporting to the AP.
The device may report time windows with interference and a pattern
of the windows, for example, using a proprietary signaling frame or
an existing unscheduled automatic power save delivery (U-APSD)
action frame (e.g., add traffic stream (ATS) frame). The device may
notify the AP of the time windows during which the station is not
available for receiving packets. The AP and mobile device may set
up a BlockACK session to enable aggregated media access control
(MAC) protocol data unit (A-MPDU) transmissions from the AP to the
device. The device may send a trigger frame (e.g., PS-Poll) after
the channel becomes available. In response, the AP may send an
acknowledgment (ACK) followed by an A-MPDU with a size (e.g., # of
sub-frames) adjusted according to the interference information.
Thus, the size of the A-MPDU may be adjusted dynamically to fit the
Wi-Fi time window that exists before the next interference window.
The AP also may adjust the A-MPDU sizes to other non-coexistence
stations using the interference information. Further, the AP may
fragment the A-MPDU (or MPDU) using the interference
information.
[0099] The scheduling techniques presented herein are generally
described in connection with WLANs for simplicity. The same or
similar techniques, however, may be used for various other wireless
communications systems such as cellular wireless systems,
peer-to-peer wireless communications, ad hoc networks, satellite
communications systems, and other systems. The terms "system" and
"network" may be used interchangeably.
[0100] Referring to FIG. 17A, an example 1700-a of coexisting
communications at a mobile device is depicted. In this example, the
mobile device may be a station 115 and may communicate with a WLAN
AP 105, such as described above with respect to FIG. 1. As shown,
the mobile device may communicate concurrently with the AP and
another device via Wi-Fi (WLAN) and BT, respectively. BT
communications 1705 and WLAN communications 1710 are illustrated in
FIG. 17A as employing time division duplexing (TDD) on the mobile
device. Alternatively or additionally, frequency division duplexing
(FDD) may be employed to avoid mutual interference between WLAN and
BT.
[0101] FIG. 17B illustrates an example 1700-b of coexisting
communications at a mobile device. As above, the mobile device may
be a station 115 and may communicate with a WLAN AP 105, such as
described above with respect to FIG. 1. In this example, the mobile
device may communicate concurrently with the AP and another device
via Wi-Fi (WLAN) and LTE, respectively. LTE uplink (UL)
communications 1715 and LTE downlink (DL)/WLAN communications 1720
are illustrated in FIG. 17B as employing TDD on the mobile device
to avoid mutual interference between WLAN and LTE.
[0102] FIG. 17C illustrates an example 1700-c of coexisting
communications at a mobile device. As above, the mobile device may
be a station 115 and may communicate with a WLAN AP 105, such as
described above with respect to FIG. 1. In this example, the mobile
device may communicate concurrently with the AP via Wi-Fi (WLAN) to
access the Internet and with another device via Wi-Fi over a P2P
network or tunneled direct link setup (TDLS). WLAN communications
1725 on channel a may retrieve video and/or audio data from the
Internet and P2P/TDLS communications 1730 on channel b may send the
data to a displaying television. The WLAN communications 1725 and
the P2P/TDLS communications 1730 are illustrated in FIG. 17C as
employing TDD on the mobile device because the Wi-Fi cannot be
active on both channels a and b at the same time.
[0103] FIG. 17D illustrates an example 1700-d of coexisting
communications at a mobile device. As above, the mobile device may
be a station 115 and may communicate with a WLAN AP 105, such as
described above with respect to FIG. 1. In this example, the mobile
device may communicate using social Wi-Fi. The mobile device may
have to tune to a discovery channel, e.g., channel a, periodically
to perform communications 1735 for discovering other devices or to
be discovered by other devices. When not in a discovery mode, the
mobile device may perform social Wi-Fi (WLAN) communications 1740
on channel b. The discovery communications 1735 and the social
Wi-Fi communications 1740 are illustrated in FIG. 17D as employing
TDD on the mobile device because the Wi-Fi cannot be active on both
channels a and b at the same time. Thus, the discovery time
intervals (e.g., discovery windows) may be considered to be time
windows during which the mobile device is not available for social
Wi-Fi communications.
[0104] Existing solutions for coexisting communications at a mobile
device, such as the coexisting communications depicted in FIGS.
17A-D, may not fully utilize the capacity of the WLAN radio of the
mobile device. For example, a coexistence solution may involve a
power save poll (PS-POLL) being sent from the mobile device to the
AP when the mobile device is available to receive data via WLAN.
The AP may respond to the PS-POLL by sending data to the mobile
device. However, the AP may be able to deliver only one packet upon
each PS-POLL. Overhead associated with the PS-POLL and potential
processing delay at the AP may significantly limit WLAN
throughput.
[0105] Another coexistence solution may involve a clear-to-send
(CTS) signal, such as CTS-to-self. The CTS signal may block the
entire basic service set (BSS), blocking transmissions from all
other devices (e.g., stations) in the BSS. Such blocking may
degrade the overall performance of the BSS.
[0106] When the CTS-based solution is used, the mobile device may
explicitly disable A-MPDU to conservatively avoid collisions
between AP's A-MPDU transmissions and BT activities on the mobile
device, for example. As A-MPDU transmissions are employed to
increase throughput, the foregoing existing solutions may be
unsatisfactory or unsuitable.
[0107] With reference now to FIG. 18, an example 1800 of
transmissions between a station (STA) and an AP, such as between a
station 115 and AP 105 of FIG. 1, according to one approach for
taking into consideration scheduling information of other
coexisting Tx/Rx activities on the STA is illustrated. In this
example, the STA at some point determines interference information
(e.g., schedule, timing, etc.) regarding the coexisting Tx/Rx
activities on the STA. The interference information may include
information on time windows with interference from the coexisting
Tx/Rx activities, pattern(s) of the interference time windows, etc.
The STA may be considered to not be available for Wi-Fi during
interference time windows.
[0108] The interference information may be provided to the AP by
the STA using propriety signaling frames or leveraging unscheduled
automatic power save delivery (U-APSD). For example, the STA may
use an add traffic stream (ATS) frame 1805 to notify the AP of the
time windows during which the STA is not available for receiving
packets. The ATS frame 1805 may be referred to as a coexistence
action frame in the context of this disclosure. In response to the
ATS frame, the AP may transmit an acknowledgment (ACK) frame 1810-a
to the STA. The STA and the AP may set up a BlockACK session to
enable data transmissions, such as MPDU or A-MPDU transmissions,
from the AP to the STA.
[0109] As noted above, the interference information provided to the
AP via the ATS frame 1805 may indicate time windows 1815 with
interference and a pattern of the windows, for example. The
predefined field of the ATS frame 1805 are capable of providing
limited information to the AP. However, the ATS frame includes an
additional field for providing vendor-specific information. This
additional field may be used to provide additional interference
information to the AP. Examples of additional interference
information may include an estimated duration and/or interference
level of each time window (e.g., interference time window) during
which Wi-Fi at the STA is not available, and/or clock drift between
the coexisting radios (e.g., WLAN and BT or LTE).
[0110] A simple periodic pattern of interference time windows 1815
is illustrated in FIG. 18 for clarity, with a period 1820. Also for
simplicity, the interference time windows 1815 are illustrated as
having a same duration 1825.
[0111] After the ATS frame 1805 has been transmitted by the STA and
acknowledged by the AP, a first interference time window 1815-a may
occur, during which the STA may be considered to be unavailable for
Wi-Fi communications. After the first interference time window
1815-a, the STA may transmit a first trigger frame (e.g., a
PS-Poll) 1830-a to the AP to indicate that the STA is ready to
receive data from the AP. The AP may send an ACK frame 1810-b in
response, and then transmit data 1835-a as a first A-MPDU, for
example. Using the interference information received via the ATS
frame 1805 from the STA, the AP may adjust a size (e.g., number of
sub-frames) of the outgoing A-MPDU 1835-a so that the A-MPDU 1835-a
may be successfully delivered within an available time window
before a subsequent interference time window 1815-b occurs. The STA
may transmit an ACK frame 1810-c in response upon successfully
receiving the first A-MPDU 1835-a.
[0112] Additionally or alternatively, the AP may fragment the
A-MPDU 1835 (or an MPDU) using the interference information if the
available time window is not long enough to fit the entire A-MPDU.
Such interference-information aware fragmentation may enable the
STA to operate robustly (e.g., good Wi-Fi throughput) even when
channel conditions are poor (e.g., such that not even a single
packet may be transmitted successfully). For example, poor
conditions may cause the AP to drop its physical layer (PHY) data
rate due to WLAN transmission failures (e.g., caused by coexistence
interference), which may lower overall network performance.
Adjusting the number of sub-frames in an A-MPDU and/or fragmenting
an A-MPDU as described herein may increase successful WLAN
transmissions by avoiding interference time windows and potential
collisions that would otherwise result. In particular, adjusting
the fragmentation size may help at least some data to be
transmitted successfully. Thus, the approaches described herein may
help to avoid the AP dropping its PHY rate, the potential increase
in collisions/transmission failures resulting from the AP dropping
its PHY rate, the potential further lowering of the APs PHY rate in
response to the increase in collisions/transmission failures, and
so on, which eventually may render the Wi-Fi link of the AP
unusable.
[0113] The AP may not be able to completely avoid overlapping
between A-MPDU transmissions and interference time windows using
the interference information, for example, due to a lack of
fine-grained timing control of outgoing frames by the AP. In such
case, the AP may calculate which part(s) of the A-MPDU may get
corrupted by the overlapping interference and may ignore the
part(s) in PHY rate control/adaptation. Such calculation may be
using the actual transmission time of the A-MPDU and the actual
start of the overlapping interference time window.
[0114] As illustrated in FIG. 18, the STA may send a second trigger
frame 1830-b to the AP after the second interference time window
1815-b to indicate that the STA is ready to receive further data
from the AP. The AP may send an ACK frame 1810-d in response, and
then transmit data 1835-b as a second A-MPDU, for example. Using
the interference information received via the ATS frame 1805 from
the STA, the AP may adjust a size of the outgoing A-MPDU 1835-b so
that the A-MPDU 1835-b may be successfully delivered within an
available time window before a subsequent interference time window
1815-c occurs.
[0115] As shown, the adjusted size of the second A-MPDU 1835-b may
differ from the adjusted size of the first A-MPDU 1835-a. In this
example, the second A-MPDU 1835-b may be larger because the
available time window before the subsequent interference time
window 1815-c occurs is longer due to the second trigger frame
1830-b being sent sooner after the second interference time window
1815-b, as compared to the timing of the first trigger frame 1830-a
after the first interference time window 1815-a. This is only one
example of dynamically adjusting the size of an A-MPDU to fit the
available non-interference time window. In practice, lengths of the
available non-interference time windows may vary, for example,
based on the duration 1825 of the preceding interference time
window 1815 and the timing of the next interference time window
1815.
[0116] Special handling may be needed for retransmissions. If a
retransmission of a packet to the STA cannot be performed in time
because Wi-Fi will become unavailable, it may be desirable to avoid
having the packet cause head-of-the-line blocking. When packets to
other STAs can be transmitted, the packet to the STA may be
buffered and the retry count of the packet for any later
transmission may be remembered.
[0117] The approach described above with respect to FIG. 18
involves the STA determining interference information regarding the
coexisting Tx/Rx activities on the STA and the STA transmitting the
determined interference information to the AP. Additionally or
alternatively, the AP may determine interference information of the
STA by estimating the interference information implicitly, such as
described below.
[0118] In some embodiments, the STA may be configured to attempt to
stop the AP from transmitting packets to the STA when Wi-Fi is not
available at the STA for receiving packets. The STA may transmit
CTS frames and/or power save control frames (e.g., PS-Poll frames,
QoS-Null frames, etc.) to attempt to stop the AP from transmitting
packets to the STA. A pattern of such frames may be used by the AP
to estimate whether the STA has an active coexistence radio, as
well as to estimate information regarding the time windows during
which Wi-Fi is unavailable for the STA. Using such estimated
interference information, the AP may attempt to deliver data (e.g.,
MPDUs and/or A-MPDUs) to the STA. Such an approach may be employed,
for example, when the AP has a relatively high confidence level
regarding the estimated interference information or as long as the
transmitted data is acknowledged by the STA as having been received
successfully.
[0119] FIG. 19 shows a timing diagram 1900 that illustrates an
approach for deriving timing information to be included, for
example, in the ATS frame 1805 discussed above with respect to FIG.
18. Timing information in the notification from the STA to the AP
may be derived from the timing synchronization function (TSF) clock
for WLAN and the clock for the coexisting radio at the STA. On the
STA, the WLAN radio and the BT (or LTE) radio typically run on
different clocks. The BT clock may run independently from the STA
TSF clock and timing of BT activities are derived from the BT
clock. In order to derive the timing information to be reported to
the AP, the timing of BT activities based on the STA TSF clock may
be determined.
[0120] The timing diagram 1900 includes a timeline 1905 for the BT
clock of the STA, a timeline 1910 for the TSF clock of the STA, and
a timeline 1915 for the TSF clock of the AP. BT time windows
(representing BT activities) 1920-a, 1920-b, 1920-c and 1920-d are
shown as occurring at times t.sub.1, t.sub.3, t.sub.4 and t.sub.5,
respectively, based on the BT clock. When an ATS frame 1925 is
prepared at time t.sub.2 on the BT clock (time T.sub.1' on the TSF
clock of the STA), a time offset to the next BT time window is set
according to the BT clock as t.sub.3-t.sub.2, where t.sub.3 is the
start of next BT time window 1920-b based on the BT clock.
Accordingly, the start time of the BT window 1920-b based on the
TSF clock will be T.sub.1'+t.sub.3-t.sub.2. The interval between BT
time windows 1920 may be calculated based on BT clock only. As
noted above, the STA TSF clock (for WLAN) may be synchronized with
the AP TSF clock, for example, using AP beacons. The difference
between the STA TSF clock and the AP TSF clock is typically very
small (e.g., less than 25 .mu.s). A guard time may be set that is
greater than or equal to the absolute value of T.sub.1'-T.sub.1,
for example, to account for this difference.
[0121] In addition to dynamically adjusting the size of A-MPDUs
sent to the mobile device/station having coexisting/concurrent
communications as described above, various embodiments may have the
AP adjust the size of A-MPDUs sent to another mobile device/STA
that does not have coexisting/concurrent communications. The AP may
use the interference information provided to the AP from the
coexistence station and/or implicitly determine by the AP, such as
described above, to guide the adjustment of the size of A-MPDUs
sent to the non-coexistence station.
[0122] Adjusting the size of A-MPDUs sent to the non-coexistence
station(s) may improve overall throughput, and also may improve
fairness with respect to the coexistence station. As illustrated in
the diagram 2000-a of FIG. 20A, the coexistence station (STA-c) may
be at a disadvantage when competing for the WLAN medium with a
non-coexistence or regular station (STA-r) in the same BSS.
[0123] The STA-c may have interference time windows 2005-a, 2005-b,
etc., for example, due to concurrently active radios. When the
Wi-Fi radio of the STA-c becomes available at the end of the first
interference time window 2005-a, there may be an ongoing
transmission 2010 of data to the STA-r. At the end of the ongoing
transmission 2010, the STA-r may send an ACK frame 2015 to the AP.
The AP may recognize and respond to a trigger frame (e.g., PS-Poll)
2020 only after the ACK frame 2015 is received by the AP. Thus, the
ongoing transmission 2010 postpones a transmission 2025 of data
(e.g., following an ACK frame 2030 from the AP to the STA-c) from
the AP to the STA-c and thus limits throughput for the STA-c, for
example, by allowing for a relatively small adjusted-sized A-MPDU
for the transmission 2025 (e.g., with time for an ACK frame 2035
from the STA-c to the AP) before the next interference time window
2005-b occurs. It should be understood that this problem may be
exacerbated by the ever increasing WLAN devices and traffic in a
network, which often may be the case in places such as airports,
coffee shops, bookstores, libraries, etc.
[0124] Having the AP adjust the A-MPDU size to the non-coexistence
station(s) may improve throughput for the coexistence station and
fairness to the coexistence station. An example of this approach is
illustrated in the diagram 2000-b of FIG. 20B. As in FIG. 20A, the
coexistence station STA-c may have interference time windows
2005-a, 2005-b, etc. In this example, however, when the AP sends a
transmission 2010-a to the STA-r, the AP may adjust the size of the
A-MPDU (e.g., shortened as compared to the A-MPDU size of the
transmission 2010 in FIG. 20A) so that the transmission 2010-a
stops around the time when the Wi-Fi radio of the STA-c is going to
become available.
[0125] Accordingly, an ACK frame 2015-a at the end of the
transmission 2010-a may be sent by the STA-r to the AP sooner than
in the example of FIG. 20A. Thus, the AP may recognize and respond
to a trigger frame 2020-a sooner than in the example of FIG. 20A,
and sends a transmission 2025-a of data (e.g., following an ACK
frame 2030-a from the AP to the STA-c) to the STA-c. As shown, the
available time window for the transmission 2025-a before the next
interference time window 2005-b occurs may allow for a larger
adjusted-sized A-MPDU for the transmission 2025-a (as compared to
the available time window for the transmission 2025 in FIG. 20A).
The shortened A-MPDU size may give the STA-c a better opportunity
to gain access to the medium.
[0126] The foregoing examples illustrate how the AP may manage
downlink traffic, which may be the most common scenario. However,
the AP may control the parameters of a BlockACK session even for
uplink traffic to help a coexistence station gain its share of the
medium. If a non-coexistence station blocks transmissions from/to a
coexistence station more often that is acceptable (e.g., greater
than a threshold number of times and/or number of times within a
certain time interval), the AP may reduce the size of the A-MPDU or
may even disable the BlockACK for the transmissions from the
non-coexistence station to the AP.
[0127] With reference now to FIG. 21, an example 2100 of
transmissions between a coexistence station STA-c and an AP and
transmissions between a non-coexistence or regular station STA-r
and the AP according to one embodiment is illustrated. This
embodiment may implement an algorithm that employs the following
information: interference information (e.g., schedule of
interfering Tx and/or Rx activities at the coexistence station;
whether there is any pending data for the coexistence station at
the AP; whether the coexistence station has been bypassed for its
turn based on the scheduling policy of the AP; and, a list of
non-coexistence stations. Thus, according to the embodiment
illustrated in FIG. 21, whether a transmission to the STA-c has
been delayed due to interference. If so, the AP may transmit to
some other STA, such as the STA-r during the interference and may
give a priority for the medium to the STA-c right after the
interference has ended.
[0128] The STA-c may have interference time windows 2105-a, 2105-b,
etc., for example, due to concurrently active radios. Although not
shown, interference information for the STA-c may be provided to
the AP by the STA and/or may be derived implicitly by the AP, such
as described above. After a first transmission 2110 of data to the
STA-r and a corresponding ACK frame 2115 from the STA-r to the AP,
the STA-c may have its turn to use the medium (e.g., based on the
scheduling policy of the AP, such as round-robin, by access class,
etc.).
[0129] However, because the Wi-Fi radio of the STA-c may be
unavailable due to the first interference time window 2105-a, there
may be only a small time window to send data to the STA-c. When the
time window is too small for at least k (e.g., with a default value
of 1) packet transmissions to the STA-c, allowing transmissions to
other STAs (e.g., STA-r) from the AP may provide a better
utilization of the medium rather than waiting for the STA-c to
become available for reception (e.g., waiting for the interference
time window to transpire). Thus, because the transmission of data
waiting at the AP for the STA-c may be delayed, the AP may bypass
the turn of the STA-c and set a flag, denoted 2120 in FIG. 21, to
indicate that the STA-c has been bypassed due to the interference
schedule of the STA-c.
[0130] The AP may choose a random regular station (e.g., STA-r) if
multiple regular stations have data pending at the AP, which may
avoid favoring one particular regular station. In this example, a
transmission 2125 to the STA-r, including a corresponding ACK frame
2130 from the STA-r to the AP may occur and end slightly after the
first interference time window 2105-a. For example, even though
there may be ten sub-frames of data waiting at the AP for the
STA-r, the AP may adjust the size (e.g., truncate) the A-MPDU of
the transmission 2125 to include only two sub-frames, denoted by
2135, so that the transmission 2125 ends soon after the first
interference time window 2105-a. This may allow the STA-c to detect
the end of this communication (transmission 2125 and ACK frame
2130) between the AP and the STA-r and to compete for the medium
relatively soon thereafter (e.g., almost immediately).
[0131] If the AP knows when the interference is over (e.g., with a
certain degree of accuracy, the AP may begin transmitting data to
the STA-c right after the transmission 2125 to the STA-r is
completed (e.g., acknowledged by the STA-r). If the AP does not
know the end time of the first interference time window 2105-a, the
STA-c may employ a trigger (TRG) frame 2140 to notify the AP that
first interference time window 2105-a has ended and the STA-c is
ready to receive data from the AP. In such case, the STA-c may
compete for the medium using the trigger frame 2140 with a wait
time T (either fixed or dynamically set) that is shorter than a
distributed inter-frame space DIFS plus a random backoff. T may be
based on DIFS, reduced inter-frame space (RIFS) or short
inter-frame space (SIFS). In some embodiments, a default value for
T may be the SIFS. The shorter the wait time T, the greater the
chance that the STA-c may win the medium time for the AP.
[0132] After the STA-c wins the medium time using the trigger frame
2120-a as shown in FIG. 21, the AP may transmit an ACK frame 2130
followed by a transmission 2025 of data to the STA-c. As discussed
above, the size of an A-MPDU of the transmission 2025 may be
adjusted to fit the available time window before the next
interference time window 2025-b of the STA-c so that the
transmission 2025 may be successfully completed.
[0133] Upon receiving an ACK frame 2155 from the STA-c indicating
that the transmission 2150 was received successfully, the AP may
clear the flag, denoted 2160 in FIG. 21, that was previously set to
indicate that the STA-c had been bypassed. After the flag is
cleared, a transmission to the STA-r that occurs during the
interference time window 2105-b may not be adjusted (e.g.,
truncated) by the AP based on the interference information, for
example, because the STA-c successfully received the transmission
2150.
[0134] Use of the flag may be modified, as appropriate or desired,
based on certain conditions. For example, if a transmission to the
STA-c fails, the flag may remain set. Also for example, if the
STA-c fails, for a certain number of times (e.g., with a default
value being 1), to utilize the medium time allocated to the STA-c,
the AP may clear the flag.
[0135] In the case of multiple coexistence stations in the BSS, the
AP may track collisions between trigger frames from the coexistence
stations. Using such collision information, the AP may backoff the
waiting time T for all but one of the coexistence stations. The one
of the coexistence stations may be determined randomly, for
example, to provide random access to the medium for the multiple
coexistence stations.
[0136] Using an order of bypassing, the AP may set different wait
time (T) values for the multiple coexistence stations. The
different T values may establish a priority for the coexistence
stations, such as by setting the T values in accordance with the
order with the first bypassed coexistence station having a shortest
T value, and so on. The setting of the different T values may
involve sending non-standard messages to the multiple coexistence
stations. However, the overhead associated with such messages may
be reduced by adjusting (e.g., shortening) only the T value for the
first bypassed coexistence station and leaving the T value(s) for
the other coexistence station(s) at a default value. As the flags
are successively removed, the next coexistence station in line may
have its T value adjusted.
[0137] In addition to dynamically adjusting the size of A-MPDUs
sent to the mobile device/station having coexisting/concurrent
communications and/or adjusting the size of A-MPDUs sent to another
mobile device/STA that does not have coexisting/concurrent
communications, the AP may be configured to identify certain
sub-frames errors using the interference information. Sub-frame
errors, such as those at the end of an A-MPDU which are corrupted
by the scheduled interference, may be predicted using the
interference information. For example, based on the actual
transmission time and configuration, the AP may find that the last
three sub-frames overlap with the interference time window.
[0138] The AP may handle (e.g., resolve, avoid, render innocuous,
etc.) the predicted sub-frame errors by treating the errors in rate
control. For example, the AP may ignore errors of the last three
sub-frames when calculating the packet error rate, which is used in
determining the PHY rate for transmissions to the mobile
device/station.
[0139] With reference now to FIG. 22, a block diagram 2200
illustrates a device 2205 that may be used to implement various
embodiments of the approaches for dealing with coexistence
interference as described herein. The device 2205 may be an example
of various aspects of the APs 105 or stations 115 described with
reference to FIG. 1. The device 2205, or portions thereof, may also
be a processor. The device 2205 may include a receiver 2210, a
coexistence interference manager 2215, and/or a transmitter 2220.
Each of these components may be in communication with each other.
The device 2205, through the receiver 2210, the coexistence
interference manager 2215, and/or the transmitter 2220, may be
configured to perform the various operations (e.g., determining
interference information, transmit/receive interference
information, adjusting a size of an A-MPDU (or MPDU),
receive/transmit A-MPDUs (or MPDUs), identify sub-frame errors,
etc.) described herein. The receiver 2210, the coexistence
interference manager 2215, and/or the transmitter 2220 also may be
configured to cooperate with other components (e.g., a rate
adaptation controller--not shown) of the device 2205 to carry out
the various operations described herein, such as discussed above
with respect to FIGS. 18-21. Either alone or in combination with
each other and/or other components not shown, the foregoing
components of the device 2205 may be examples of means for
performing the various operations described herein.
[0140] Turning to FIG. 23, a diagram 2300 is shown that illustrates
a station 115-c that may be used to implement various embodiments
of the approaches for dealing with coexistence interference as
described herein. The station 115-c may have various other
configurations and may be included or be part of a personal
computer (e.g., laptop computer, netbook computer, tablet computer,
etc.), a cellular telephone, a PDA, a digital video recorder (DVR),
an internet appliance, a gaming console, an e-readers, etc. The
station 115-c may have an internal power supply (not shown), such
as a small battery, to facilitate mobile operation. The station
115-c may be an example of the stations 115 of FIG. 1.
[0141] The station 115-c may include a processor 2305, a memory
2310, transceiver(s) 2325, antennas 2330, and a coexistence
interference manager 2320. The coexistence interference manager
2320 may be an example of the coexistence interference manager 2215
of FIG. 22. Each of these components may be in communication with
each other, directly or indirectly, over a bus(es) for example. The
coexistence interference manager 2320 may be a computer program
product and/or a controller element(s) of the processor 2305.
[0142] The memory 2310 may include random access memory (RAM) and
read-only memory (ROM). The memory 2310 may store
computer-readable, computer-executable software (SW) code 2315
containing instructions that are configured to, when executed,
cause the processor 2305 to perform the various functions described
herein for dealing with coexistence interference. Alternatively,
the software code 2315 may not be directly executable by the
processor 2305 but may be configured to cause the computer (e.g.,
when compiled and executed) to perform functions described
herein.
[0143] The processor 2305 may include an intelligent hardware
device, e.g., a central processing unit (CPU), a microcontroller,
an application-specific integrated circuit (ASIC), etc. The
processor 2305 may process information received through the
transceiver 2325 and/or to be sent to the transceiver 2325 for
transmission through the antennas 2330. The processor 2305 may
handle, alone or in connection with the coexistence interference
manager 2320, various aspects for dealing with coexistence
interference.
[0144] The transceiver(s) 2325 may be configured to communicate
bi-directionally with APs 105 in FIG. 1. The transceiver(s) 2325
may be implemented as a transmitter(s) and a separate receiver(s),
for example, to operate the station 115-c in accordance with
different radio access technologies (e.g., WLAN, BT, LTE, etc.).
The transceiver(s) 2325 may include a modem configured to modulate
packets and provide the modulated packets to the antennas 2330 for
transmission, and to demodulate packets received from the antennas
2330. While the station 115-c may include a single antenna, there
may be examples in which the station 115-c may include multiple
antennas 2330.
[0145] The components of the station 115-c may be configured to
implement aspects discussed above with respect to FIGS. 18-21, and
those aspects may not be repeated here for the sake of brevity.
Moreover, the components of the station 115-c may be configured to
implement aspects discussed below with respect to FIG. 25, and
those aspects may not be repeated here also for the sake of
brevity. Thus, either alone or in combination with each other
and/or other components not shown, the foregoing components of the
station 115-c may be examples of means for performing the various
operations associated with the stations as described herein.
[0146] Turning to FIG. 24, a diagram 2400 is shown that illustrates
an access point or AP 105-c that may be used to implement various
embodiments of the approaches for dealing with coexistence
interference as described herein. In some examples, the AP 105-c
may be an example of the APs 105 of FIG. 1. The AP 105-c may
include a processor 2410, a memory 2420, a transceiver 2430,
antennas 2440, a coexistence interference manager 2445 and/or an
A-MPDU generator 2450. The A-MPDU generator 2450 and/or the
coexistence interference manager 2445 may be an example of the
coexistence interference manager 2215 of FIG. 22. In some examples,
the AP 105-c may also include one or both of an AP communicator
2480 and a network communicator 2485. Each of these components may
be in communication with each other, directly or indirectly, over a
bus(es) 2415.
[0147] The memory 2420 may include RAM and ROM. The memory 2420 may
also store computer-readable, computer-executable software (SW)
code 2425 containing instructions that are configured to, when
executed, cause the processor 2410 to perform various functions
described herein for dealing with coexistence interference.
Alternatively, the software code 2425 may not be directly
executable by the processor 2410 but may be configured to cause the
computer, e.g., when compiled and executed, to perform functions
described herein.
[0148] The processor 2410 may include an intelligent hardware
device, e.g., a CPU, a microcontroller, an ASIC, etc. The processor
2410 may process information received through the transceiver 2430,
the AP communicator 2480, and/or the network communicator 2485. The
processor 2410 may also process information to be sent to the
transceiver 2430 for transmission through the antennas 2440, to the
AP communicator 2480, and/or to the network communicator 2485. The
processor 2410 may handle, alone or in connection with the A-MPDU
generator 2450 and/or the coexistence interference manager 2445,
various aspects related to coexistence interference as discussed
above and further below.
[0149] The transceiver 2430 may include a modem configured to
modulate packets and provide the modulated packets to the antennas
2440 for transmission, and to demodulate packets received from the
antennas 2440. The transceiver 2430 may be implemented as a
transmitter(s) and a separate receiver(s). The transceiver 2430 may
be configured to communicate bi-directionally, via the antennas
2440, with a station(s) 115 as illustrated in FIG. 1 or FIG. 23,
for example. The AP 105-c may typically include multiple antennas
2440 (e.g., an antenna array). The AP 105-c may communicate with a
core network 2405 through the network communicator 2485. The AP
105-c may communicate with other APs, such as an access point 105-k
and an access point 105-m, using the AP communicator 2480.
[0150] According to the architecture of FIG. 24, the AP 105-c may
further include a communications manager 2455. The communications
manager 2455 may manage communications with stations and/or other
devices as illustrated in the WLAN 100 of FIG. 1, for example. The
communications manager 2455 may be in communication with some or
all of the other components of the AP 105-c via the bus or buses
2415. Alternatively, functionality of the communications manager
2455 may be implemented as a component of the transceiver 2430, as
a computer program product, and/or as a controller element(s) of
the processor 2410.
[0151] The components of the AP 105-c may be configured to
implement aspects discussed above with respect to FIGS. 18-21, and
those aspects may not be repeated here for the sake of brevity.
Moreover, the components of the AP 105-c may be configured to
implement aspects discussed below with respect to FIG. 26 and those
aspects may not be repeated here also for the sake of brevity.
Thus, either alone or in combination with each other and/or other
components not shown, the foregoing components of the AP 105-c may
be examples of means for performing the various operations
associated with the APs as described herein.
[0152] Turning next to FIG. 25, a flow diagram is described for a
method 2500 for dealing with coexistence interference in accordance
with various examples. The method 2500 may be implemented using,
for example, the stations 115 of FIG. 1 or 23; or the device 2300
of FIG. 23, for example. At block 2505, the station may determine
interference information relating to activity by an interfering
radio thereof. This operation may be performed by the coexistence
interference manager 2320 of FIG. 23 or the coexistence
interference manager 2215 of FIG. 22, for example.
[0153] At block 2510, the station may report (e.g., transmit) the
determined interference information to an access point (AP). This
operation may be performed by the coexistence interference manager
2320 in conjunction with the processor 2305, the memory 2310 and/or
the transceiver(s) 2325 of FIG. 23 or the coexistence interference
manager 2215 in conjunction with the transmitter 2220 of FIG. 22,
for example.
[0154] Then, at block 2515, the station may receive an MPDU (or
A-MPDU) from the AP, which may have adjusted a size of the MPDU (or
A-MPDU) using the determined interference information. This
operation may be performed by the transceiver(s) 2325 in
conjunction with the processor 2305, and/or a communications
manager (not shown) of FIG. 23 or the receiver 2210 in conjunction
with a communications manager (not shown) of FIG. 22, for
example.
[0155] Turning next to FIG. 26, a flow diagram is described for a
method 2600 for dealing with coexistence interference in accordance
with various examples. The method 2600 may be implemented using,
for example, the APs 105 of FIG. 1 or 24; or the device 2205 of
FIG. 22, for example. At block 2605, the may determine interference
information of a station relating to activity by an interfering
radio of the station. This operation may be performed by receiving
the interference information from the station and/or by implicitly
determining (e.g., estimating) the interference information, such
as described above. Thus, this operation may be performed by the
coexistence interference manager 2445 in conjunction with the
communications manager 2455, the processor 2410, the memory 2420
and/or the transceiver 2430 of FIG. 24, or the coexistence
interference manager 2215 in conjunction with the receiver 2210 of
FIG. 22.
[0156] At block 2310, the AP may adjust a size of an MPDU (or
A-MPDU) using the determined interference information. This
operation may be performed by generating the MPDU (or A-MPDU) with
a desired number of sub-frames and/or fragmenting the MPDU (or
A-MPDU), such as described above. Thus, this operation also may be
performed by the coexistence interference manager 2445 and/or the
A-MPDU generator 2450 in conjunction with the processor 2410 and/or
the memory 2420 of FIG. 24, or the coexistence interference manager
2215 of FIG. 22.
[0157] Then, at block 2615, the AP may transmit the size-adjusted
MPDU (or A-MPDU) to the station in accordance with the determined
interference information. This operation may be performed, for
example, in response to a triggering frame received by the AP from
the station, or may be performed using the AP's knowledge of the
end of a preceding transmission to a different station, such as
described above. Thus, this operation also may be performed by the
coexistence interference manager 2445 and/or the A-MPDU generator
2450 in conjunction with the communications manager 2455 and/or
transceiver 2430 of FIG. 24, or the coexistence interference
manager 2215 in conjunction with a communications manager (not
shown) and/or the transmitter 2220 of FIG. 22, for example.
[0158] The methods described above with respect to FIGS. 25 and 26
are only examples of method that may be employed to deal with
coexistence interference of a station. As such, various
modifications of the operations may be made and/or additional
operations may be added to achieve other methods in accordance with
this disclosure.
[0159] The detailed description set forth above in connection with
the appended drawings describes exemplary examples and does not
represent the only examples that may be implemented or that are
within the scope of the claims. The term "exemplary" when used in
this description means "serving as an example, instance, or
illustration," and not "preferred" or "advantageous over other
examples." The detailed description includes specific details for
the purpose of providing an understanding of the described
techniques. These techniques, however, may be practiced without
these specific details. In some instances, well-known structures
and devices are shown in block diagram form in order to avoid
obscuring the concepts of the described examples.
[0160] Information and signals may be represented using any of a
variety of different technologies and techniques. For example,
data, instructions, commands, information, signals, bits, symbols,
and chips that may be referenced throughout the above description
may be represented by voltages, currents, electromagnetic waves,
magnetic fields or particles, optical fields or particles, or any
combination thereof.
[0161] The various illustrative blocks and modules described in
connection with the disclosure herein may be implemented or
performed with a general-purpose processor, a digital signal
processor (DSP), an application specific integrated circuit (ASIC),
a field programmable gate array (FPGA) or other programmable logic
device, discrete gate or transistor logic, discrete hardware
components, or any combination thereof designed to perform the
functions described herein. A general-purpose processor may be a
microprocessor, but in the alternative, the processor may be any
conventional processor, controller, microcontroller, or state
machine. A processor may also be implemented as a combination of
computing devices, e.g., a combination of a DSP and a
microprocessor, multiple microprocessors, a microprocessor(s) in
conjunction with a DSP core, or any other such configuration.
[0162] The functions described herein may be implemented in
hardware, software executed by a processor, firmware, or any
combination thereof. If implemented in software executed by a
processor, the functions may be stored on or transmitted over as an
instruction(s) or code on a computer-readable medium. Other
examples and implementations are within the scope and spirit of the
disclosure and appended claims. For example, due to the nature of
software, functions described above can be implemented using
software executed by a processor, hardware, firmware, hardwiring,
or combinations of any of these. Features implementing functions
may also be physically located at various positions, including
being distributed such that portions of functions are implemented
at different physical locations. Also, as used herein, including in
the claims, "or" as used in a list of items prefaced by "at least
one of" indicates a disjunctive list such that, for example, a list
of "at least one of A, B, or C" means A or B or C or AB or AC or BC
or ABC (i.e., A and B and C).
[0163] Computer-readable media includes both computer storage media
and communication media including any medium that facilitates
transfer of a computer program from one place to another. A storage
medium may be any available medium that can be accessed by a
general purpose or special purpose computer. By way of example, and
not limitation, computer-readable media can comprise RAM, ROM,
EEPROM, CD-ROM or other optical disk storage, magnetic disk storage
or other magnetic storage devices, or any other medium that can be
used to carry or store desired program code means in the form of
instructions or data structures and that can be accessed by a
general-purpose or special-purpose computer, or a general-purpose
or special-purpose processor. Also, any connection is properly
termed a computer-readable medium. For example, if the software is
transmitted from a website, server, or other remote source using a
coaxial cable, fiber optic cable, twisted pair, digital subscriber
line (DSL), or wireless technologies such as infrared, radio, and
microwave, then the coaxial cable, fiber optic cable, twisted pair,
DSL, or wireless technologies such as infrared, radio, and
microwave are included in the definition of medium. Disk and disc,
as used herein, include compact disc (CD), laser disc, optical
disc, digital versatile disc (DVD), floppy disk and blu-ray disc
where disks usually reproduce data magnetically, while discs
reproduce data optically with lasers. Combinations of the above are
also included within the scope of computer-readable media.
[0164] The previous description of the disclosure is provided to
enable a person skilled in the art to make or use the disclosure.
Various modifications to the disclosure will be readily apparent to
those skilled in the art, and the generic principles defined herein
may be applied to other variations without departing from the
spirit or scope of the disclosure. Throughout this disclosure the
term "example" or "exemplary" indicates an example or instance and
does not imply or require any preference for the noted example.
Thus, the disclosure is not to be limited to the examples and
designs described herein but is to be accorded the widest scope
consistent with the principles and novel features disclosed
herein.
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