U.S. patent application number 15/910716 was filed with the patent office on 2018-07-05 for block acknowledgement with fragmentation acknowledgement signaling.
The applicant listed for this patent is QUALCOMM Incorporated. Invention is credited to Santosh Paul ABRAHAM, Alfred ASTERJADHI, Gwendolyn Denise BARRIAC, George CHERIAN, James Simon CHO, Gang DING, Guido Robert FREDERIKS, Rahul MALIK, Simone MERLIN.
Application Number | 20180191480 15/910716 |
Document ID | / |
Family ID | 56130713 |
Filed Date | 2018-07-05 |
United States Patent
Application |
20180191480 |
Kind Code |
A1 |
ASTERJADHI; Alfred ; et
al. |
July 5, 2018 |
BLOCK ACKNOWLEDGEMENT WITH FRAGMENTATION ACKNOWLEDGEMENT
SIGNALING
Abstract
Certain aspects of the present disclosure provide methods and
apparatus for using a block acknowledgement (BlockAck) frame
capable of acknowledging fragments. One example method for wireless
communications generally includes receiving a plurality of protocol
data units (PDUs) (e.g., media access control (MAC) protocol data
units (MPDUs)); determining whether each of the PDUs was
successfully received and whether each of the PDUs is associated
with a non-fragmented service data unit (SDU) (e.g., MAC service
data unit (MSDU)) or a fragmented SDU; and outputting for
transmission a BlockAck frame comprising a bitmap field indicating
a receive status for the non-fragmented and fragmented SDUs based
on the determination.
Inventors: |
ASTERJADHI; Alfred; (San
Diego, CA) ; MERLIN; Simone; (San Diego, CA) ;
CHERIAN; George; (San Diego, CA) ; ABRAHAM; Santosh
Paul; (San Diego, CA) ; BARRIAC; Gwendolyn
Denise; (Encinitas, CA) ; MALIK; Rahul; (San
Diego, CA) ; DING; Gang; (San Diego, CA) ;
FREDERIKS; Guido Robert; (Watsonville, CA) ; CHO;
James Simon; (Mountain View, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM Incorporated |
San Diego |
CA |
US |
|
|
Family ID: |
56130713 |
Appl. No.: |
15/910716 |
Filed: |
March 2, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14978039 |
Dec 22, 2015 |
9929847 |
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15910716 |
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62201516 |
Aug 5, 2015 |
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62190239 |
Jul 8, 2015 |
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62183176 |
Jun 22, 2015 |
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62096168 |
Dec 23, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 72/04 20130101;
H04L 1/1685 20130101; H04L 5/0055 20130101; H04L 1/1614
20130101 |
International
Class: |
H04L 5/00 20060101
H04L005/00; H04L 1/16 20060101 H04L001/16; H04W 72/04 20060101
H04W072/04 |
Claims
1. An apparatus for wireless communications, comprising: a receiver
configured to receive a plurality of protocol data units (PDUs); at
least one processor coupled with a memory and configured to
determine whether each of the PDUs was successfully received and
whether each of the PDUs carries a non-fragmented service data unit
(SDU) or a fragmented SDU, wherein at least one of the PDUs
comprises at least one fragmented SDU; and a transmitter configured
to transmit a block acknowledgment (BlockAck) frame comprising a
starting sequence control (SSC) field and a bitmap field indicating
a receive status for any non-fragmented SDUs and the at least one
fragmented SDU based on the determination, wherein: the bitmap
field in the BlockAck frame has a variable length, the variable
length is indicated by a value of one or more most significant bits
of a fragment number (FN) in the BlockAck frame, and the value of
the FN is indicated in the SSC field.
2. The apparatus of claim 1, wherein the at least one fragmented
SDU is received in an aggregated MPDU (A-MPDU).
3. The apparatus of claim 1, wherein a number of the non-fragmented
and fragmented SDUs that can be acknowledged by the bitmap field in
the BlockAck frame is variable.
4. The apparatus of claim 1, wherein each bit in the bitmap field
in the BlockAck frame indicates the receive status for one of the
non-fragmented SDUs or at least one of: the first fragment of one
of the fragmented SDUs, all fragments of one of the fragmented
SDUs, or a sole fragment for one of the fragmented SDUs.
5. The apparatus of claim 1, wherein the at least one processor is
further configured to participate in a negotiation, with a
transmitter of the plurality of PDUs, for one or more fragmentation
parameters used in transmitting or processing the fragmented
SDUs.
6. The apparatus of claim 5, wherein the one or more parameters
comprise at least one of: a maximum number of concurrent fragmented
transmissions supported by the apparatus or a minimum fragment
length supported by the apparatus.
7. The apparatus of claim 5, wherein the at least one processor is
further configured to provide an indication of whether
fragmentation is supported during the negotiation.
8. The apparatus of claim 5, wherein the negotiation is performed
during at least one of: a BlockAck setup or an association with the
transmitter.
9. The apparatus of claim 5, wherein the negotiation comprises
exchanging an Add Block Acknowledgment (ADDBA) Extension
Information Element (IE) in at least one of: an ADDBA request or an
ADDBA response.
10. The apparatus of claim 1, wherein a value of a least
significant bit (LSB) in the FN in the BlockAck frame indicates
whether the BlockAck frame indicates a receive status of
non-fragmented SDUs or fragmented SDUs.
11. The apparatus of claim 10, wherein a value of zero for the
value of the LSB indicates a non-fragmented SDU and a non-zero
value for the value of the LSB indicates a fragmented SDU.
12. The apparatus of claim 1, wherein each fragmented SDU comprises
four fragments.
13. An apparatus for wireless communications, comprising: a
transmitter configured to transmit a plurality of protocol data
units (PDUs), wherein: each of the PDUs carries a non-fragmented
service data unit (SDU) or a fragmented SDU, and at least one of
the PDUs comprises at least one fragmented SDU; a receiver
configured to receive a block acknowledgment (BlockAck) frame
comprising a starting sequence control (SSC) field and a bitmap
field indicating a receive status for any non-fragmented SDUs and
the at least one fragmented SDU, wherein: the bitmap field in the
BlockAck frame has a variable length, the variable length is
indicated by values of one or more most significant bits of a
fragment number (FN) in the BlockAck frame; and the value of the FN
is indicated in the SSC field; at least one processor coupled with
a memory and configured to process the bitmap field in the BlockAck
frame to determine whether the non-fragmented SDUs and the at least
one fragmented SDU were successfully received.
14. The apparatus of claim 13, wherein the at least one fragmented
SDU is transmitted in an aggregated MPDU (A-MPDU).
15. The apparatus of claim 13, wherein a number of the
non-fragmented and fragmented SDUs that can be acknowledged by the
bitmap field in the BlockAck frame is variable.
16. The apparatus of claim 13, wherein the at least one processor
is further configured to participate in a negotiation, with a
receiver, for one or more fragmentation parameters used in
transmitting or processing the fragmented SDUs.
17. The apparatus of claim 13, wherein a value of a least
significant bit (LSB) in the FN in the BlockAck frame indicates
whether the BlockAck frame indicates a receive status of
non-fragmented SDUs or fragmented SDUs.
18. The apparatus of claim 17, wherein a value of zero for the
value of the LSB indicates a non-fragmented SDU and a non-zero
value for the value of the LSB indicates a fragmented SDU.
19. The apparatus of claim 13, wherein each fragmented SDU
comprises four fragments.
20. A method for wireless communications, comprising: receiving a
plurality of protocol data units (PDUs); determining whether each
of the PDUs was successfully received and whether each of the PDUs
carries a non-fragmented service data unit (SDU) or a fragmented
SDU, wherein at least one of the PDUs comprises at least one
fragmented SDU; and transmitting a block acknowledgment (BlockAck)
frame comprising a starting sequence control (SSC) field and a
bitmap field indicating a receive status for any non-fragmented
SDUs and the at least one fragmented SDU based on the
determination, wherein: the bitmap field in the BlockAck frame has
a variable length, the variable length is indicated by a value of
one or more most significant bits of a fragment number (FN) in the
BlockAck frame, and the value of the FN is indicated in the SSC
field.
Description
CLAIM OF PRIORITY UNDER 35 U.S.C. .sctn. 119
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/978,039 (Atty. Dkt. No. 151150US), filed
Dec. 22, 2015, which claims the benefit of U.S. Provisional Patent
Application Ser. No. 62/096,168 (Atty. Dkt. No. 151150USL), filed
Dec. 23, 2014, U.S. Provisional Patent Application Ser. No.
62/183,176 (Atty. Dkt. No. 151150USL02), filed Jun. 22, 2015, U.S.
Provisional Patent Application Ser. No. 62/190,239 (Atty. Dkt. No.
151150USL03), filed Jul. 8, 2015, U.S. Provisional Patent
Application Ser. No. 62/201,516 (Atty. Dkt. No. 151150USL04), filed
Aug. 5, 2015, each assigned to the assignee hereof and hereby
expressly incorporated by reference herein.
BACKGROUND
Field of the Disclosure
[0002] Certain aspects of the present disclosure generally relate
to wireless communications and, more particularly, to using a
shortened block acknowledgement (BlockAck) frame capable of
acknowledging fragments.
Description of Related Art
[0003] Wireless communication networks are widely deployed to
provide various communication services such as voice, video, packet
data, messaging, broadcast, etc. These wireless networks may be
multiple-access networks capable of supporting multiple users by
sharing the available network resources. Examples of such
multiple-access networks include Code Division Multiple Access
(CDMA) networks, Time Division Multiple Access (TDMA) networks,
Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA
(OFDMA) networks, and Single-Carrier FDMA (SC-FDMA) networks.
[0004] In order to address the issue of increasing bandwidth
requirements that are demanded for wireless communications systems,
different schemes are being developed. Once such scheme allows
multiple user terminals to communicate with a single access point
by sharing the channel resources while achieving high data
throughputs. Multiple Input Multiple Output (MIMO) technology
represents one such approach that has emerged as a popular
technique for communication systems. MIMO technology has been
adopted in several wireless communications standards such as the
Institute of Electrical and Electronics Engineers (IEEE) 802.11
standard. The IEEE 802.11 denotes a set of Wireless Local Area
Network (WLAN) air interface standards developed by the IEEE 802.11
committee for short-range communications (e.g., tens of meters to a
few hundred meters). Another scheme to achieve greater throughput
is HEW (High Efficiency WiFi or High Efficiency WLAN) being
developed by the IEEE 802.11ax task force. The goal of this scheme
is to achieve a throughput 4.times. that of IEEE 802.11ac.
SUMMARY
[0005] The systems, methods, and devices of the disclosure each
have several aspects, no single one of which is solely responsible
for its desirable attributes. Without limiting the scope of this
disclosure as expressed by the claims which follow, some features
will now be discussed briefly. After considering this discussion,
and particularly after reading the section entitled "Detailed
Description," one will understand how the features of this
disclosure provide advantages that include improved communications
in a wireless network.
[0006] Certain aspects of the present disclosure generally relate
to using a shortened block acknowledgement (BlockAck) frame capable
of acknowledging fragments. The shortened BlockAck frame may
include a bitmap field having a shorter length than that of a basic
BlockAck frame (e.g., <128 octets).
[0007] Certain aspects of the present disclosure provide a method
for wireless communications by an apparatus. The method generally
includes receiving a plurality of protocol data units (PDUs),
determining whether each of the PDUs was successfully received and
whether each of the PDUs is associated with a non-fragmented
service data unit (SDU) or a fragmented SDU, and outputting for
transmission a shortened BlockAck frame comprising a bitmap field
indicating a receive status for the non-fragmented and fragmented
SDUs based on the determination.
[0008] Certain aspects of the present disclosure provide an
apparatus for wireless communications. The apparatus generally
includes a processing system configured to receive a plurality of
PDUs, to determine whether each of the PDUs was successfully
received and whether each of the PDUs is associated with a
non-fragmented SDU or a fragmented SDU, and to output for
transmission a shortened BlockAck frame comprising a bitmap field
indicating a receive status for the non-fragmented and fragmented
SDUs based on the determination.
[0009] Certain aspects of the present disclosure provide an
apparatus for wireless communications. The apparatus generally
includes means for receiving a plurality of PDUs, means for
determining whether each of the PDUs was successfully received and
whether each of the PDUs is associated with a non-fragmented SDU or
a fragmented SDU, and means for outputting for transmission a
shortened BlockAck frame comprising a bitmap field indicating a
receive status for the non-fragmented and fragmented SDUs based on
the determination.
[0010] Certain aspects of the present disclosure provide a
non-transitory computer-readable medium for wireless
communications. The medium has instructions stored thereon, which
are executable (e.g., by an apparatus, such as a computer
processor) to receive a plurality of PDUs, to determine whether
each of the PDUs was successfully received and whether each of the
PDUs is associated with a non-fragmented SDU or a fragmented SDU,
and to output for transmission a shortened BlockAck frame
comprising a bitmap field indicating a receive status for the
non-fragmented and fragmented SDUs based on the determination.
[0011] Certain aspects of the present disclosure provide a wireless
node. The wireless node generally includes at least one antenna, a
receiver, a processing system, and a transmitter. The receiver is
generally configured to receive a plurality of PDUs via the at
least one antenna. The processing system is generally configured to
determine whether each of the PDUs was successfully received and
whether each of the PDUs is associated with a non-fragmented DU or
a fragmented SDU. The transmitter is generally configured to
transmit a shortened BlockAck frame comprising a bitmap field
indicating a receive status for the non-fragmented and fragmented
SDUs based on the determination.
[0012] Certain aspects of the present disclosure provide a method
for wireless communications by an apparatus. The method generally
includes outputting a plurality of PDUs for transmission, wherein
each of the PDUs is associated with a non-fragmented SDU or a
fragmented SDU, receiving a shortened BlockAck frame comprising a
bitmap field indicating a receive status for the non-fragmented and
fragmented SDUs, and processing the bitmap field in the shortened
BlockAck frame to determine whether the non-fragmented and
fragmented SDUs were successfully received.
[0013] Certain aspects of the present disclosure provide an
apparatus for wireless communications. The apparatus generally
includes a processing system configured to output a plurality of
PDUs for transmission, wherein each of the PDUs is associated with
a non-fragmented SDU or a fragmented SDU, to receive a shortened
BlockAck frame comprising a bitmap field indicating a receive
status for the non-fragmented and fragmented SDUs, and to process
the bitmap field in the shortened BlockAck frame to determine
whether the non-fragmented and fragmented SDUs were successfully
received.
[0014] Certain aspects of the present disclosure provide an
apparatus for wireless communications. The apparatus generally
includes means for outputting a plurality of PDUs for transmission,
wherein each of the PDUs is associated with a non-fragmented SDU or
a fragmented SDU, means for receiving a shortened BlockAck frame
comprising a bitmap field indicating a receive status for the
non-fragmented and fragmented SDUs, and means for processing the
bitmap field in the shortened BlockAck frame to determine whether
the non-fragmented and fragmented SDUs were successfully
received.
[0015] Certain aspects of the present disclosure provide a
non-transitory computer-readable medium for wireless
communications. The medium has instructions stored thereon, which
are executable (e.g., by an apparatus, such as a processing system)
to output a plurality of PDUs for transmission, wherein each of the
PDUs is associated with a non-fragmented SDU or a fragmented SDU,
to receive a shortened BlockAck frame comprising a bitmap field
indicating a receive status for the non-fragmented and fragmented
SDUs, and to process the bitmap field in the shortened BlockAck
frame to determine whether the non-fragmented and fragmented SDUs
were successfully received.
[0016] Certain aspects of the present disclosure provide a wireless
node. The wireless node generally includes at least one antenna, a
receiver, a processing system, and a transmitter. The transmitter
is generally configured to transmit a plurality of PDUs via the at
least one antenna, wherein each of the PDUs is associated with a
non-fragmented SDU or a fragmented SDU. The receiver is generally
configured to receive a shortened BlockAck frame comprising a
bitmap field indicating a receive status for the non-fragmented and
fragmented SDUs. The processing system is generally configured to
process the bitmap field in the shortened BlockAck frame to
determine whether the non-fragmented and fragmented SDUs were
successfully received.
[0017] To the accomplishment of the foregoing and related ends, the
one or more aspects comprise the features hereinafter fully
described and particularly pointed out in the claims. The following
description and the annexed drawings set forth in detail certain
illustrative features of the one or more aspects. These features
are indicative, however, of but a few of the various ways in which
the principles of various aspects may be employed, and this
description is intended to include all such aspects and their
equivalents.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 illustrates an example wireless communications
network, in accordance with certain aspects of the present
disclosure.
[0019] FIG. 2 is a block diagram of an example access point (AP)
and user terminals, in accordance with certain aspects of the
present disclosure.
[0020] FIG. 3 is a block diagram of an example wireless device, in
accordance with certain aspects of the present disclosure.
[0021] FIG. 4 illustrates using a shortened block acknowledgment
(Block Ack or BA) frame capable of acknowledging one or more
fragments in an aggregated media access control (MAC) protocol data
unit (A-MPDU), in accordance with certain aspects of the present
disclosure.
[0022] FIG. 5 illustrates a shortened BlockAck frame having a
variable-length bitmap field, in accordance with certain aspects of
the present disclosure.
[0023] FIG. 6 illustrates a shortened BlockAck frame having a
constant-length bitmap field, in accordance with certain aspects of
the present disclosure.
[0024] FIG. 7 is a flow diagram of example operations for
outputting a shortened BlockAck frame for transmission, in
accordance with certain aspects of the present disclosure.
[0025] FIG. 7A illustrates example means capable of performing the
operations shown in FIG. 7.
[0026] FIG. 8 is a flow diagram of example operations for using a
shortened BlockAck frame for acknowledging fragmented and
non-fragmented service data units (SDUs), in accordance with
certain aspects of the present disclosure.
[0027] FIG. 8A illustrates example means capable of performing the
operations shown in FIG. 8.
[0028] FIG. 9 is a table of example BlockAck frame variant
encoding, in accordance with certain aspects of the present
disclosure.
[0029] FIG. 10 illustrates an example exchange using fragmentation,
in accordance with aspects of the present disclosure.
[0030] FIG. 11 illustrates an example information element (IE), in
accordance with certain aspects of the present disclosure.
[0031] FIG. 12 illustrates an example exchange using fragmentation,
in accordance with aspects of the present disclosure.
[0032] FIGS. 13A and 13B illustrate example exchanges using
fragmentation, in accordance with aspects of the present
disclosure.
[0033] FIGS. 14A and 14B illustrate example exchanges using
fragmentation, in accordance with aspects of the present
disclosure.
[0034] To facilitate understanding, identical reference numerals
have been used, where possible, to designate identical elements
that are common to the figures. It is contemplated that elements
disclosed in one embodiment may be beneficially utilized on other
embodiments without specific recitation.
DETAILED DESCRIPTION
[0035] Aspects of the present disclosure provide techniques for
allowing data units to be sent as multiple fragments that may be
collectively or separately acknowledged. As will be described in
greater detail below, such fragmentation may result in efficient
use of uplink and downlink resources. In some cases, fragmentation
parameters may be negotiated to achieve certain objectives, such as
reducing the amount of memory and processing resources used by both
originating and receiving devices to process fragmented
transmissions.
[0036] Various aspects of the disclosure are described more fully
hereinafter with reference to the accompanying drawings. This
disclosure may, however, be embodied in many different forms and
should not be construed as limited to any specific structure or
function presented throughout this disclosure. Rather, these
aspects are provided so that this disclosure will be thorough and
complete, and will fully convey the scope of the disclosure to
those skilled in the art. Based on the teachings herein one skilled
in the art should appreciate that the scope of the disclosure is
intended to cover any aspect of the disclosure disclosed herein,
whether implemented independently of or combined with any other
aspect of the disclosure. For example, an apparatus may be
implemented or a method may be practiced using any number of the
aspects set forth herein. In addition, the scope of the disclosure
is intended to cover such an apparatus or method which is practiced
using other structure, functionality, or structure and
functionality in addition to or other than the various aspects of
the disclosure set forth herein. It should be understood that any
aspect of the disclosure disclosed herein may be embodied by one or
more elements of a claim.
[0037] The word "exemplary" is used herein to mean "serving as an
example, instance, or illustration." Any aspect described herein as
"exemplary" is not necessarily to be construed as preferred or
advantageous over other aspects.
[0038] Although particular aspects are described herein, many
variations and permutations of these aspects fall within the scope
of the disclosure. Although some benefits and advantages of the
preferred aspects are mentioned, the scope of the disclosure is not
intended to be limited to particular benefits, uses, or objectives.
Rather, aspects of the disclosure are intended to be broadly
applicable to different wireless technologies, system
configurations, networks, and transmission protocols, some of which
are illustrated by way of example in the figures and in the
following description of the preferred aspects. The detailed
description and drawings are merely illustrative of the disclosure
rather than limiting, the scope of the disclosure being defined by
the appended claims and equivalents thereof.
[0039] The techniques described herein may be used for various
broadband wireless communication systems, including communication
systems that are based on an orthogonal multiplexing scheme.
Examples of such communication systems include Spatial Division
Multiple Access (SDMA) system, Time Division Multiple Access (TDMA)
system, Orthogonal Frequency Division Multiple Access (OFDMA)
system, and Single-Carrier Frequency Division Multiple Access
(SC-FDMA) system. An SDMA system may utilize sufficiently different
directions to simultaneously transmit data belonging to multiple
user terminals. A TDMA system may allow multiple user terminals to
share the same frequency channel by dividing the transmission
signal into different time slots, each time slot being assigned to
different user terminal. An OFDMA system utilizes orthogonal
frequency division multiplexing (OFDM), which is a modulation
technique that partitions the overall system bandwidth into
multiple orthogonal sub-carriers. These sub-carriers may also be
called tones, bins, etc. With OFDM, each sub-carrier may be
independently modulated with data. An SC-FDMA system may utilize
interleaved FDMA (IFDMA) to transmit on sub-carriers that are
distributed across the system bandwidth, localized FDMA (LFDMA) to
transmit on a block of adjacent sub-carriers, or enhanced FDMA
(EFDMA) to transmit on multiple blocks of adjacent sub-carriers. In
general, modulation symbols are sent in the frequency domain with
OFDM and in the time domain with SC-FDMA.
[0040] The teachings herein may be incorporated into (e.g.,
implemented within or performed by) a variety of wired or wireless
apparatuses (e.g., nodes). In some aspects, a wireless node
implemented in accordance with the teachings herein may comprise an
access point or an access terminal.
[0041] An access point ("AP") may comprise, be implemented as, or
known as a Node B, Radio Network Controller ("RNC"), evolved Node B
(eNB), Base Station Controller ("BSC"), Base Transceiver Station
("BTS"), Base Station ("BS"), Transceiver Function ("TF"), Radio
Router, Radio Transceiver, Basic Service Set ("BSS"), Extended
Service Set ("ESS"), Radio Base Station ("RBS"), or some other
terminology.
[0042] An access terminal ("AT") may comprise, be implemented as,
or known as a subscriber station, a subscriber unit, a mobile
station (MS), a remote station, a remote terminal, a user terminal
(UT), a user agent, a user device, user equipment (UE), a user
station, or some other terminology. In some implementations, an
access terminal may comprise a cellular telephone, a cordless
telephone, a Session Initiation Protocol ("SIP") phone, a wireless
local loop ("WLL") station, a personal digital assistant ("PDA"), a
handheld device having wireless connection capability, a Station
("STA"), or some other suitable processing device connected to a
wireless modem. Accordingly, one or more aspects taught herein may
be incorporated into a phone (e.g., a cellular phone or smart
phone), a computer (e.g., a laptop), a tablet, a portable
communication device, a portable computing device (e.g., a personal
data assistant), an entertainment device (e.g., a music or video
device, or a satellite radio), a global positioning system (GPS)
device, or any other suitable device that is configured to
communicate via a wireless or wired medium. In some aspects, the AT
may be a wireless node. Such wireless node may provide, for
example, connectivity for or to a network (e.g., a wide area
network such as the Internet or a cellular network) via a wired or
wireless communication link.
An Example Wireless Communication System
[0043] FIG. 1 illustrates a wireless communications system 100 in
which aspects of the disclosure may be performed. For example, a
user terminal 120 (or a processing system therein) may receive a
plurality of protocol data units (PDUs), determine whether each of
the PDUs was successfully received (e.g., from the access point
110) and whether each of the PDUs is associated with a
non-fragmented service data unit (SDU) or a fragmented SDU; and
output for transmission a shortened block acknowledgment (BlockAck)
frame comprising a bitmap field indicating a receive status for the
non-fragmented and fragmented SDUs based on the determination.
[0044] The system 100 may be, for example, a multiple-access
multiple-input multiple-output (MIMO) system with access points and
user terminals. For simplicity, only one access point 110 is shown
in FIG. 1. An access point is generally a fixed station that
communicates with the user terminals and may also be referred to as
a base station or some other terminology. A user terminal may be
fixed or mobile and may also be referred to as a mobile station, a
wireless device, or some other terminology. Access point 110 may
communicate with one or more user terminals 120 at any given moment
on the downlink and uplink. The downlink (i.e., forward link) is
the communication link from the access point to the user terminals,
and the uplink (i.e., reverse link) is the communication link from
the user terminals to the access point. A user terminal may also
communicate peer-to-peer with another user terminal.
[0045] A system controller 130 may provide coordination and control
for these APs and/or other systems. The APs may be managed by the
system controller 130, for example, which may handle adjustments to
radio frequency power, channels, authentication, and security. The
system controller 130 may communicate with the APs via a backhaul.
The APs may also communicate with one another, e.g., directly or
indirectly via a wireless or wireline backhaul.
[0046] While portions of the following disclosure will describe
user terminals 120 capable of communicating via Spatial Division
Multiple Access (SDMA), for certain aspects, the user terminals 120
may also include some user terminals that do not support SDMA.
Thus, for such aspects, an AP 110 may be configured to communicate
with both SDMA and non-SDMA user terminals. This approach may
conveniently allow older versions of user terminals ("legacy"
stations) to remain deployed in an enterprise, extending their
useful lifetime, while allowing newer SDMA user terminals to be
introduced as deemed appropriate.
[0047] The system 100 employs multiple transmit and multiple
receive antennas for data transmission on the downlink and uplink.
The access point 110 is equipped with N.sub.ap antennas and
represents the multiple-input (MI) for downlink transmissions and
the multiple-output (MO) for uplink transmissions. A set of K
selected user terminals 120 collectively represents the
multiple-output for downlink transmissions and the multiple-input
for uplink transmissions. For pure SDMA, it is desired to have
N.sub.ap.gtoreq.K.gtoreq.1 if the data symbol streams for the K
user terminals are not multiplexed in code, frequency or time by
some means. K may be greater than N.sub.ap if the data symbol
streams can be multiplexed using TDMA technique, different code
channels with CDMA, disjoint sets of subbands with OFDM, and so on.
Each selected user terminal transmits user-specific data to and/or
receives user-specific data from the access point. In general, each
selected user terminal may be equipped with one or multiple
antennas (i.e., N.sub.ut.gtoreq.1). The K selected user terminals
can have the same or different number of antennas.
[0048] The system 100 may be a time division duplex (TDD) system or
a frequency division duplex (FDD) system. For a TDD system, the
downlink and uplink share the same frequency band. For an FDD
system, the downlink and uplink use different frequency bands. The
system 100 may also utilize a single carrier or multiple carriers
for transmission. Each user terminal may be equipped with a single
antenna (e.g., in order to keep costs down) or multiple antennas
(e.g., where the additional cost can be supported). The system 100
may also be a TDMA system if the user terminals 120 share the same
frequency channel by dividing transmission/reception into different
time slots, each time slot being assigned to different user
terminal 120.
[0049] FIG. 2 illustrates a block diagram of a system 100 in which
aspects of the present disclosure may be performed. For example,
the access point 110 (or a processing system therein) may output a
plurality of PDUs for transmission, wherein each of the PDUs is
associated with a non-fragmented SDU or a fragmented SDU; receive a
shortened BlockAck frame comprising a bitmap field (e.g., a Block
Ack bitmap field) indicating a receive status for the
non-fragmented and fragmented SDUs; and process the bitmap field in
the shortened BlockAck frame to determine whether the
non-fragmented and fragmented SDUs were successfully received.
[0050] The system 100 may be, for example, a MIMO system with
access point 110 and two user terminals 120m and 120x. The access
point 110 is equipped with N.sub.ap antennas 224a through 224ap.
User terminal 120m is equipped with N.sub.ut,m antennas 252ma
through 252mu, and user terminal 120x is equipped with N.sub.ut,x
antennas 252xa through 252xu. The access point 110 is a
transmitting entity for the downlink and a receiving entity for the
uplink. Each user terminal 120 is a transmitting entity for the
uplink and a receiving entity for the downlink. As used herein, a
"transmitting entity" is an independently operated apparatus or
device (e.g., an AP or STA) capable of transmitting data via a
wireless channel, and a "receiving entity" is an independently
operated apparatus or device (e.g., an AP or STA) capable of
receiving data via a wireless channel. In the following
description, the subscript "dn" denotes the downlink, the subscript
"up" denotes the uplink, N.sub.up user terminals are selected for
simultaneous transmission on the uplink, N.sub.dn user terminals
are selected for simultaneous transmission on the downlink,
N.sub.up may or may not be equal to N.sub.dn, and N.sub.up and
N.sub.dn may be static values or can change for each scheduling
interval. The beam-steering or some other spatial processing
technique may be used at the access point and user terminal.
[0051] On the uplink, at each user terminal 120 selected for uplink
transmission, a transmit (TX) data processor 288 receives traffic
data from a data source 286 and control data from a controller 280.
The controller 280 may be coupled with a memory 282. TX data
processor 288 processes (e.g., encodes, interleaves, and modulates)
the traffic data for the user terminal based on the coding and
modulation schemes associated with the rate selected for the user
terminal and provides a data symbol stream. A TX spatial processor
290 performs spatial processing on the data symbol stream and
provides N.sub.ut,m transmit symbol streams for the N.sub.ut,m
antennas. Each transmitter unit (TMTR) 254 receives and processes
(e.g., converts to analog, amplifies, filters, and frequency
upconverts) a respective transmit symbol stream to generate an
uplink signal. N.sub.ut,m transmitter units 254 provide N.sub.ut,m
uplink signals for transmission from N.sub.ut,m antennas 252 to the
access point.
[0052] N.sub.up user terminals may be scheduled for simultaneous
transmission on the uplink. Each of these user terminals performs
spatial processing on its data symbol stream and transmits its set
of transmit symbol streams on the uplink to the access point.
[0053] At access point 110, N.sub.ap antennas 224a through 224ap
receive the uplink signals from all N.sub.up user terminals
transmitting on the uplink. Each antenna 224 provides a received
signal to a respective receiver unit (RCVR) 222. Each receiver unit
222 performs processing complementary to that performed by
transmitter unit 254 and provides a received symbol stream. An RX
spatial processor 240 performs receiver spatial processing on the
N.sub.ap received symbol streams from N.sub.ap receiver units 222
and provides N.sub.up recovered uplink data symbol streams. The
receiver spatial processing is performed in accordance with the
channel correlation matrix inversion (CCMI), minimum mean square
error (MMSE), soft interference cancellation (SIC), or some other
technique. Each recovered uplink data symbol stream is an estimate
of a data symbol stream transmitted by a respective user terminal.
An RX data processor 242 processes (e.g., demodulates,
deinterleaves, and decodes) each recovered uplink data symbol
stream in accordance with the rate used for that stream to obtain
decoded data. The decoded data for each user terminal may be
provided to a data sink 244 for storage and/or a controller 230 for
further processing. The controller 230 may be coupled with a memory
232.
[0054] On the downlink, at access point 110, a TX data processor
210 receives traffic data from a data source 208 for N.sub.dn user
terminals scheduled for downlink transmission, control data from a
controller 230, and possibly other data from a scheduler 234. The
various types of data may be sent on different transport channels.
TX data processor 210 processes (e.g., encodes, interleaves, and
modulates) the traffic data for each user terminal based on the
rate selected for that user terminal. TX data processor 210
provides N.sub.dn downlink data symbol streams for the N.sub.dn
user terminals. A TX spatial processor 220 performs spatial
processing (such as a precoding or beamforming, as described in the
present disclosure) on the N.sub.dn downlink data symbol streams,
and provides N.sub.ap transmit symbol streams for the N.sub.ap
antennas. Each transmitter unit 222 receives and processes a
respective transmit symbol stream to generate a downlink signal.
N.sub.ap transmitter units 222 providing N.sub.ap downlink signals
for transmission from N.sub.ap antennas 224 to the user terminals.
The decoded data for each user terminal may be provided to a data
sink 272 for storage and/or a controller 280 for further
processing.
[0055] At each user terminal 120, N.sub.ut,m antennas 252 receive
the N.sub.ap downlink signals from access point 110. Each receiver
unit 254 processes a received signal from an associated antenna 252
and provides a received symbol stream. An RX spatial processor 260
performs receiver spatial processing on N.sub.ut,m received symbol
streams from N.sub.ut,m receiver units 254 and provides a recovered
downlink data symbol stream for the user terminal. The receiver
spatial processing is performed in accordance with the CCMI, MMSE
or some other technique. An RX data processor 270 processes (e.g.,
demodulates, deinterleaves and decodes) the recovered downlink data
symbol stream to obtain decoded data for the user terminal.
[0056] At each user terminal 120, a channel estimator 278 estimates
the downlink channel response and provides downlink channel
estimates, which may include channel gain estimates, SNR estimates,
noise variance and so on. Similarly, at access point 110, a channel
estimator 228 estimates the uplink channel response and provides
uplink channel estimates. Controller 280 for each user terminal
typically derives the spatial filter matrix for the user terminal
based on the downlink channel response matrix H.sub.dn,m for that
user terminal. Controller 230 derives the spatial filter matrix for
the access point based on the effective uplink channel response
matrix H.sub.up,eff. Controller 280 for each user terminal may send
feedback information (e.g., the downlink and/or uplink
eigenvectors, eigenvalues, SNR estimates, and so on) to the access
point. Controllers 230 and 280 also control the operation of
various processing units at access point 110 and user terminal 120,
respectively.
[0057] FIG. 3 illustrates various components that may be utilized
in a wireless device 302 that may be employed within the system
100. The wireless device 302 is an example of a device that may be
configured to implement the various methods described herein. For
example, the wireless device may implement operations 700 or 800
illustrated in FIGS. 7 and 8, respectively. The wireless device 302
may be an access point 110 or a user terminal 120.
[0058] The wireless device 302 may include a processor 304 which
controls operation of the wireless device 302. The processor 304
may also be referred to as a central processing unit (CPU). Memory
306, which may include both read-only memory (ROM) and random
access memory (RAM), provides instructions and data to the
processor 304. A portion of the memory 306 may also include
non-volatile random access memory (NVRAM). The processor 304
typically performs logical and arithmetic operations based on
program instructions stored within the memory 306. The instructions
in the memory 306 may be executable to implement the methods
described herein.
[0059] The wireless device 302 may also include a housing 308 that
may include a transmitter 310 and a receiver 312 to allow
transmission and reception of data between the wireless device 302
and a remote node. The transmitter 310 and receiver 312 may be
combined into a transceiver 314. A single or a plurality of
transmit antennas 316 may be attached to the housing 308 and
electrically coupled to the transceiver 314. The wireless device
302 may also include (not shown) multiple transmitters, multiple
receivers, and multiple transceivers.
[0060] The wireless device 302 may also include a signal detector
318 that may be used in an effort to detect and quantify the level
of signals received by the transceiver 314. The signal detector 318
may detect such signals as total energy, energy per subcarrier per
symbol, power spectral density and other signals. The wireless
device 302 may also include a digital signal processor (DSP) 320
for use in processing signals.
[0061] The various components of the wireless device 302 may be
coupled together by a bus system 322, which may include a power
bus, a control signal bus, and a status signal bus in addition to a
data bus.
Example Shortened Block Acknowledgement
[0062] As noted above, aspects of the present disclosure provide
techniques for sending data units using fragmentation, which may
result in efficient use of uplink and downlink resources. As used
herein, the term fragmentation generally refers to the process of
partitioning a data unit, such as a MAC service data unit (MSDU) or
MAC management protocol data unit (MMPDU), into smaller data units
(e.g., MPDUs) for transmission.
[0063] In some cases, the fragment length may be the same for all
fragments except for the last, which may be smaller than the others
to just accommodate a remaining portion. Additionally, the length
of each fragment (except for the last fragment), may be an even
number of octets. The length of each fragment may be limited to
never exceed a certain fragmentation threshold (e.g., with the
threshold specified by a parameter dot11FragmentationThreshold in
IEEE 802.11). In some cases, for example, if security encapsulation
is invoked, the fragment length may exceed this threshold due to
encapsulation overhead. Once a fragment is transmitted for the
first time, the frame body content and length may be fixed until
the fragment is successfully delivered to a recipient station
(STA).
[0064] Defragmentation generally refers to the process of
reassembling an MSDU/MMPDU from its constituent fragments.
Reassembly is generally performed by combining fragments in order
of fragment number (FN) subfield. A mechanism may be utilized to
identify a last fragment. For example, a fragment with the More
Fragments bit equal to 0 indicates the last fragment for this
particular MSDU/MMPDU, based on its sequence number (SN).
[0065] In certain wireless communications systems, such as IEEE
802.11ax (also known as high efficiency wireless (HEW) or high
efficiency wireless local area network (WLAN)), data rates of 750
kbps and lower are being proposed (e.g., MCS0 in 2.5 MHz), which
suggests the use of fragmentation. In multi-user (MU) operation,
where an AP communicates with multiple STAs, the AP may allocate
resources by sending a trigger frame that provides the resource
allocations per-STA for the rest of the granted transmission
opportunity (TXOP).
[0066] In an effort to fully use the allocated resource, the STA
may fragment the MSDU on-the-fly. The fragment length and the
number of fragments may be determined once the STA knows the
allocated resource for its current transmission. The fragmentation
threshold (that controls the length of fragments) may be changed
dynamically every MSDU to fully use the granted TXOP. In certain
embodiments, the fragmentation threshold may control the length of
each fragment of the same MSDU. The first fragment may be
transmitted during the allocated resource in the granted TXOP. The
remaining n-1 fragments may be queued for transmission in
subsequent TXOPs. This baseline method generates multiple
fragments, each of which are carried in an MPDU. The lower the
payload of the fragment, the larger the number of fragments (i.e.,
the higher the impact of the PHY/MAC/security overhead).
[0067] To remove some of the PHY overhead, it may be useful to
allow aggregated MPDU (A-MPDU) aggregation of fragments (with other
fragments or full MPDUs), although this adds some overhead from
A-MPDU delimiters and padding. As an example, such aggregation of
fragments may be performed in an effort to efficiently fill a low
data rate allocation (e.g., efficiently filling an allocation may
entail 2000 bytes of data: a 1500B non-fragmented MSDU plus a 500B
fragment of another, fragmented MSDU). As another example, A-MPDU
aggregation of fragments may be done to efficiently transmit the
remaining fragment of an MSDU in a subsequent transmit opportunity
(TXOP). Retransmission in a subsequent TXOP may entail fragment
aggregation. Once a packet has been fragmented and transmitted, it
should be retransmitted in the same manner; otherwise, reassembly
(defragmentation) is complicated. For certain aspects, an A-MPDU
may contain non-fragmented MSDUs and at most one fragment of an
MSDU (i.e., an A-MSDU cannot contain more than one fragment of the
same MSDU).
[0068] FIG. 4 illustrates an example aggregation of fragment MPDUs
in an A-MPDU 420, in accordance with certain aspects of the present
disclosure. In the illustrated example, MSDUs 410 with sequence
numbers 1 and 5 (SN=1 and SN=5) are unfragmented, while MSDU 410
with sequence number 2 (SN=2) is fragmented, with three fragments
shown, with fragment numbers 1, 2, and 3 (FN=1, FN=2, and FN=3). As
illustrated, a more fragment flag (MF) may be set to 1 in the first
two fragments to indicate there are more fragments to come, while
MF is set to 0 in the third fragment, indicating the last
fragment.
[0069] Such fragment aggregation may be allowed without changing
the basics of the immediate BlockAck procedure (e.g., each MSDU 410
may occupy one location of the BlockAck buffer and fragment MPDUs
occupy independent buffers) and the fragmentation/defragmentation
procedure. However, the basic BlockAck frame, capable of
acknowledging up to 64 MSDUs having up to 16 fragments each, has a
bitmap field with a length of 128 octets. A compressed BlockAck may
be used that acknowledges up to 64 MSDUs and has a bitmap field
with a length of only 8 octets. While shorter than a normal
BlockAck frame (e.g., defined by a standard), this type of
compressed BlockAck frame does not acknowledge fragmented MSDUs or
fragments thereof.
[0070] To address this, aspects of the present disclosure provide a
BlockAck frame capable of acknowledging fragmented and
non-fragmented MSDUs, but having a reduced size compared to a basic
BlockAck frame. In some cases, shortened or "compressed" BlockAck
frame may reduce overhead and be capable of acknowledging
fragmented MSDUs without significant changes in signaling of the
basic BlockAck frame.
[0071] In some cases, a recipient may select a type of Block Ack
Frame on a per A-MPDU basis. After receiving an A-MPDU, according
to this option, the recipient may generate a BlockAck frame that is
either a modified version of the compressed BlockAck frame (one
type of shortened BlockAck frame) or a basic BlockAck Frame. The
shortened BlockAck frame (labeled "Compressed BlockAck*" in FIG. 4)
may have the same length as a compressed BlockAck (32 octets with
an 8-octet bitmap). However, each bit in the shortened frame's
bitmap may indicate the receive status of a non-fragment (A-)MSDU
and one of the following: (1) the first fragment of the fragmented
MSDU; (2) all the fragments of the MSDU; or (3) the sole fragment
of the MSDU that is contained in the A-MPDU that elicited the
BlockAck frame. If a basic BlockAck frame is selected instead, this
frame has a length of 152 octets and a bitmap having a length of
128 octets. Each bit in the basic frame's bitmap indicates the
receive status of each MPDU (fragment or non-fragment) within the
receive block acknowledgment window.
[0072] In some cases, the originator may receive a shortened
BlockAck frame with partial information, which may occur when: (1)
there is no receive status indication for fragments other than the
first fragment of a given sequence number (SN); (2) there is an
unsuccessful receive status indication for at least one of the
fragments of a given SN (i.e., bit set to 0 for the SN); or (3)
there is no receive status for the sole fragment contained in the
A-MPDU that elicited the BlockAck frame. If the originator receives
a shortened BlockAck frame with partial information, then the
originator may either solicit a basic BlockAck frame by sending a
block acknowledgement request (BAR) frame or retransmit all the
fragments of the MSDU that had an unsuccessful receive status.
[0073] One disadvantage with a recipient selecting the type of
Block Ack frame is that a basic BlockAck frame may be generated as
a response in certain situations. The frequency of this happening
may depend on the number of fragments included in an A-MPDU. Rather
than use either a modified version of the compressed BlockAck frame
(32 octets) or the basic BlockAck frame (152 octets), other options
are described below for a shortened BlockAck frame having a reduced
length compared to the basic BlockAck frame, but whose information
content is not as limited as the modified version of the compressed
BlockAck frame.
[0074] As illustrated in FIG. 5, in some cases, a shortened
BlockAck frame 500 having a variable-length bitmap field 510 may be
used. This bitmap size may be dependent on a number of fragments
and may be variable, for example, between 8 and 128 octets, for
example. The shortened BlockAck frame may be used, for example, to
acknowledge 64 (A-)MSDUs and fragments up to the Fragment Number
(FN) subfield in the Block Ack Starting Sequence Control (SSC)
field 520 in the shortened BlockAck frame. FIG. 5 illustrates how
an originator and recipient may track or "keep score" of which
MSDUs/fragments have been successfully acknowledged. As will be
described in greater detail below, in some cases, parameter may be
negotiated to limit the memory overhead required for such tracking.
For example, an originator and recipient may negotiate a maximum
number of fragmented transmissions that may be handled concurrently
and/or a timer value used to flush fragments (if not all fragments
of a fragmented transmission are successfully received, even
successfully received fragments may be discarded).
[0075] The value of a Fragment Number subfield in the Block Ack SSC
field may indicate the number of fragments per sequence number (SN)
contained in the BlockAck bitmap field. When FN=0, non-fragmented
MSDUs and the first fragment of fragmented MSDUs may be
acknowledged by the shortened BlockAck frame. For other aspects,
when FN=0, at most one fragment of each fragmented MSDU that is
contained in the A-MPDU that elicited the shortened BlockAck frame
(or contained in the A-MPDU that was transmitted between two
A-MPDUs that elicited shortened BlockAck frames) and non-fragmented
MSDUs may be acknowledged by the shortened BlockAck frame. If up to
64 MSDUs may be acknowledged, this leads to a BlockAck bitmap field
having a length of 8 octets, which is the same length as the
BlockAck bitmap field in a compressed BlockAck frame. When FN=N,
non-fragment MSDUs and up to N+1 fragments of fragmented MSDUs may
be acknowledged, leading to a bitmap field length of 8*(N+1)
octets. In the worst case (e.g., where 64 MSDUs have 16 fragments),
the "shortened" BlockAck frame having a variable-length bitmap
field may be the same length as a basic BlockAck frame (152 Octets,
with a bitmap field length of 128 octets).
[0076] As illustrated in FIG. 6, in some cases, a shortened
BlockAck frame 600 having a fixed (e.g., constant-length) bitmap
field may be used for fragment-dependent signaling. In some cases,
the length of the bitmap field for the shortened BlockAck frame may
be 8 octets, and the length of the shortened BlockAck frame may be
the same as that of a compressed BlockAck frame (32 octets).
[0077] Similar to the case described above with reference to FIG.
5, a value of the Fragment Number subfield in the Block Ack SSC
field may indicate the number of fragments per SN contained in the
BlockAck bitmap field. When FN=0, non-fragmented MSDUs and the
first fragment of fragmented MSDUs may be acknowledged by the
shortened BlockAck frame. For other aspects, when FN=0, at most one
fragment of each fragmented MSDU that is contained in the A-MPDU
that elicited the shortened BlockAck frame (or contained in the
A-MPDU that was transmitted between two A-MPDUs that elicited
shortened BlockAck frames) and non-fragmented MSDUs may be
acknowledged by the shortened BlockAck frame. With a bitmap field
having a length of 8 octets, for example, up to 64 (A-)MSDUs may be
acknowledged. When FN=N, non-fragment MSDUs and up to N+1 fragments
of fragmented MSDUs may be acknowledged.
[0078] With a constant-length bitmap field, however, the shortened
BlockAck frame may acknowledge up to ceil(M/(N+1)) (A-)MSDUs, where
M is the fixed bitmap length in bits (e.g., M=64 bits=8 octets). In
other words, the number of MSDUs that may be acknowledged by each
shortened BlockAck frame with a constant-length bitmap field varies
according to the FN. In some cases, only a portion of the fragments
of the last MSDU may be acknowledged.
[0079] In some cases, for this option (i.e., at least one MSDU in
the A-MPDU is fragmented in 16 fragments) only up to 4 MSDUs can be
acknowledged (if M=64). If the number of fragments is lower, then
more MSDUs can be acknowledged.
[0080] Note that while the description above refers to the use of a
Fragment Number subfield (FN) in the Block Ack SSC field, a person
having ordinary skill in the art will realize that any such field
or subfield that is contained in the BlockAck frame itself may be
used to provide the above-described signaling (e.g., the traffic
identifier information (TID_INFO) subfield in the BA control
field). For example, the shortened BlockAck frame may be defined as
a multi-fragment BlockAck frame.
[0081] As will be described in greater detail below, a particular
variant of a BlockAck frame may be distinguished from the other
frame formats, for example, by using a reserved combination of the
Multi-TID, Compressed Bitmap, and Group Cast Retries (GCR)
subfields of the BA Control field.
[0082] For certain aspects, the TID_INFO field for a Multi-Fragment
BlockAck frame may indicate the number of MSDUs that can be
acknowledged with the frame (e.g., in units of 8 or 16, etc.),
making it possible to dynamically vary the BlockAck bitmap field as
a function of the MSDUs that can be acknowledged. For example, if
the TID_INFO is 0 and the FN is 0, then the bitmap field may be 1
octet in length and carries acknowledgement information for 8 MSDUs
and the first fragment of the MDSUs.
[0083] FIG. 7 is a flow diagram of example operations 700 for
outputting a shortened BlockAck frame for transmission, in
accordance with certain aspects of the present disclosure. The
operations 700 may be performed, for example, by an apparatus
(e.g., AP 110, user terminal 120, or wireless device 302, or a
processing system therein).
[0084] The operations 700 begin, at block 702, with the apparatus
receiving a plurality of protocol data units (PDUs) (e.g., from
another apparatus, which may be a user terminal 120 or AP 110). The
plurality of PDUs may comprise a plurality of media access control
(MAC) protocol data units (MPDUs). The plurality of MPDUs may
comprise an aggregated MPDU (A-MPDU), for example.
[0085] At block 704, the apparatus determines whether each of the
PDUs was successfully received. The apparatus also determines
whether each of the PDUs is associated with a non-fragmented
service data unit (SDU) or a fragmented SDU at block 704. For
certain aspects, at least one of the PDUs comprises a fragment of
one of the fragmented SDUs.
[0086] At block 706, the apparatus outputs a shortened block
acknowledgment (BlockAck) frame for transmission. The shortened
BlockAck frame includes a bitmap field indicating a receive status
for the non-fragmented and fragmented SDUs based on the
determination at block 704. In other words, the bits in the bitmap
field are populated according to the determination at block 704
(e.g., a logic "1" may indicate that an SDU or a fragment thereof
was successfully received, whereas a logic "0" may indicate the SDU
or fragment thereof was not successfully received). For certain
aspects, the non-fragmented and fragmented SDUs include
non-fragmented and fragmented MAC service data units (MSDUs).
[0087] According to certain aspects, the operations 700 may further
involve the apparatus receiving a block acknowledgement request
after outputting the shortened BlockAck frame for transmission at
block 706. In this case, the apparatus may output for transmission
a basic BlockAck frame in response to the block acknowledgement
request. A bitmap field in the basic BlockAck frame may indicate
the receive status for the non-fragmented SDUs and each fragment of
the fragmented SDUs based on the determination at block 704.
[0088] According to certain aspects, the operations 700 may further
involve the apparatus selecting the shortened BlockAck frame over a
basic BlockAck frame before the outputting at block 706.
[0089] According to certain aspects, the operations 700s further
involve the apparatus outputting for transmission another shortened
BlockAck frame before the receiving at block 702. In this case, the
plurality of PDUs may comprise an A-MPDU, the non-fragmented and
fragmented SDUs include non-fragmented and fragmented MSDUs, and
the A-MPDU may include at most one fragment for each of the
fragmented MSDUs.
[0090] FIG. 8 is a flow diagram of example operations 800 for using
a shortened BlockAck frame for acknowledging fragmented and
non-fragmented service data units (SDUs) (e.g., MSDUs), in
accordance with certain aspects of the present disclosure. The
operations 800 may be performed, for example, by an apparatus
(e.g., AP 110, wireless device 302, or user terminal 120, or a
processing system therein).
[0091] The operations 800 begin, at block 802, with the apparatus
outputting a plurality of protocol data units (PDUs) for
transmission. Each of the PDUs is associated with a non-fragmented
SDU or a fragmented SDU. For certain aspects, at least one of the
PDUs is a fragment of one of the fragmented SDUs. The plurality of
PDUs may comprise a plurality of media access control (MAC)
protocol data units (MPDUs). The plurality of MPDUs may comprise an
aggregated MPDU (A-MPDU), for example.
[0092] At block 804, the apparatus receives a shortened block
acknowledgment (BlockAck) frame comprising a bitmap field
indicating a receive status for the non-fragmented and fragmented
SDUs. The apparatus processes the bitmap field in the shortened
BlockAck frame, at block 806, to determine whether the
non-fragmented and fragmented SDUs were successfully received.
[0093] This particular variant of a BlockAck frame may be
distinguished from the other frame formats, for example, by using a
reserved combination of the Multi-TID, Compressed Bitmap, and Group
Cast Retries (GCR) subfields of the BA Control field. As an
example, the settings in the 6.sup.th row of table 900 in FIG. 9
may be used to indicate that the frame is a multi-fragment BlockAck
frame. For example a Multi-Fragment BlockAck frame may be
identified by setting the Multi-TID, Compressed Bitmap, and GCR
values to all 1s, and the FN described above may, for example,
either be indicated in the TID_INFO field of the BA Control field
or in the FN subfield of the BlockAck SSC field
[0094] According to certain aspects, the operations 800 may further
involve the apparatus outputting a block acknowledgement request
for transmission. This request may be output after the processing
at block 806, for example, where the processing indicated that at
least one of the non-fragmented and fragmented SDUs was not
successfully received. The apparatus may also receive a basic
BlockAck frame in response to the block acknowledgement request.
The bitmap field in the basic BlockAck frame may indicate the
receive status for each of the non-fragmented SDUs and each
fragment of the fragmented SDUs.
[0095] According to certain aspects, after the processing at block
806 (which indicated that at least one of the fragmented SDUs was
not successfully received, for example), the operations 800 may
further involve the apparatus outputting for retransmission
fragments of the at least one of the fragmented SDUs.
[0096] As noted above, the bitmap field in the shortened BlockAck
frame has a shorter length than a bitmap field in a basic BlockAck
frame. In other words, the bitmap field in the shortened BlockAck
frame may have a length less than 128 octets.
[0097] As described with reference to FIG. 6, the bitmap field in
the shortened BlockAck frame has a fixed length (e.g., 8 octets).
In this case, a number of the non-fragmented and fragmented SDUs
that can be acknowledged by the bitmap field in the shortened
BlockAck frame may be variable. For example, the number of the
non-fragmented and fragmented SDUs may be up to ceil(M/(N+1)),
where M is the fixed length in bits and where the bitmap field in
the shortened BlockAck frame can indicate the receive status for up
to N+1 fragments for the fragmented SDUs. The shortened BlockAck
frame may include a starting sequence control (SSC) field, and N
may be a fragment number (FN) indicated by the SSC field.
[0098] In certain embodiments, both N and M can be signaled in the
BlockAck frame itself. In such embodiments, any reserved field that
precedes the BlockAck Bitmap field can be used for this purpose. In
one example, the Fragment Number subfield can be used to signal
these values, wherein 0 or more bits of the Fragment Number
indicate the length of the BlockAck Bitmap field (which could take
values that are multiples of an octet (e.g., 2 Octets, 4 octets, 8
Octets 32 octets representing the value of M in bytes). In some
cases, 0 or more of the remaining bits of the Fragment Number could
represent the value of N or a function of N (e.g., those remaining
bits could indicate values of 0, 2, 4, 8 fragments). Any of the
bits of the Fragment Number can be used for this purpose. As an
example, the 2 MSBs of the Fragment Number field can indicate the
value of the BlockAck Bitmap and the 2 LSBs of the Fragment Number
can indicate the value of the Fragment Number. In this example, a
value of the 2 MSBs equal to 0 could indicate a BlockAck Bitmap
field size of 8 bytes (to be backward compatible with previous
versions of the standard), a value equal to 1 could indicate 2
Octets, a value of 2 could indicate 32 Octets, and a value of 3
could indicate for example 128 Octets. Similarly, a value of the 2
LSBs equal to 0 could indicate no fragments (to be backward
compatible as previously mentioned), for example, while a value of
1 could indicate 2 fragments, a value of 2 could indicate 4
fragments, and a value of 3 could indicate 16 fragments. In
general, any combination of the values of the Fragment Number
subfield can be used to indicate the size of the BlockAck Bitmap
length and/or the number of fragments that are being acknowledged,
as well.
[0099] As described with reference to FIG. 5, the bitmap field in
the shortened BlockAck frame has a variable length. In this case,
the variable length may be indicated by an FN in the shortened
BlockAck frame. The shortened BlockAck frame may include an SSC
field, and the FN may be indicated by the SSC field. For certain
aspects, the FN=0, and each bit in the bitmap field in the
shortened BlockAck frame may indicate the receive status for one of
the non-fragmented SDUs or the first fragment of one of the
fragmented SDUs. The bitmap field in the shortened BlockAck frame
may have a length of 8 octets, for example. For certain aspects,
the FN is a positive integer, and each bit in the bitmap field in
the shortened BlockAck frame may indicate the receive status for
one of the non-fragmented SDUs or each fragment of one of the
fragmented SDUs. In this case, the FN=N, and the bitmap field in
the shortened BlockAck frame may have a length of up to 8*(N+1)
octets, for example.
[0100] According to certain aspects, each bit in the bitmap field
in the shortened BlockAck frame may indicate the receive status for
one of the non-fragmented SDUs or the first fragment of one of the
fragmented SDUs. For other aspects, each bit in the bitmap field in
the shortened BlockAck frame may indicate the receive status for
one of the non-fragmented SDUs or collectively all fragments of one
of the fragmented SDUs.
[0101] As noted above, in some cases, a particular variant of a
BlockAck frame may be distinguished from other frame formats by
using a reserved combination of various fields, such as the
Multi-TID, Compressed Bitmap, and Group Cast Retries (GCR)
subfields of the BA Control field.
[0102] Referring to FIG. 9, as an example, the settings in the
6.sup.th row of table 900 may be used to indicate that the frame is
a multi-fragment BlockAck frame. As illustrated, a Multi-Fragment
BlockAck frame may be identified by setting the Multi-TID,
Compressed Bitmap, and GCR values to all 1s, and the FN described
above may, for example, either be indicated in the TID_INFO field
of the BA Control field or in the FN subfield of the BlockAck SSC
field.
[0103] As illustrated in the example exchange 1000 of FIG. 10, the
techniques for fragmentation presented herein may provide an
efficient way of using allocated resources in MU transmissions 1020
initiated by a trigger frame 1010 sent by an AP. Such fragmentation
may provide a means of providing feedback via a compressed Block
Ack frame 1030 (in effect, closing the UL link) for limited range
devices. In some cases, a block acknowledgement (Block Ack)
protocol may also be provided that allows fragments to be carried
in A-MPDUs when sent in MU mode. Such a protocol may help simplify
the generation of fragments at an originating device, while
reducing memory requirements at both the recipient and originating
devices (e.g., by limiting the amount of memory required to keep
track of which data units/fragments have been received). In some
cases, compressed BlockAck frames 1010 may be used to acknowledge
received fragments sent in an A-MPDU (which may be considered a
form of an enhanced HT-Immediate Block Ack protocol).
[0104] As noted above, in some cases, STAs may negotiate
fragmentation during BA setup. In other words,
fragmentation-related parameters may be exchanged during a
fragment-enabled BA session. In some cases, this negotiation may be
performed during association (when a station associates with an
AP). Regarding fragment generation at the originator, fragments may
be carried in A-MPDUs under various restrictions specified by the
recipient. These restrictions may include, for example, a maximum
number (Max #) of concurrent fragmented MSDU/MMPDUs and a maximum
number of fragments per MSDU/MMPDU. In some cases, only one
fragment per MSDU shall be carried in an A-MPDU. In some cases,
there may be no restriction (or dependency) to the length of the
fragments.
[0105] Fragment acknowledgement at the recipient may be as follows.
The recipient may keep full-state information for fragmented
MSDU/MMPDUs for the duration of the receive timer. It may be noted
that, in some cases, fragmented MSDUs may be discarded after the
receive timer has expired and the MSDU may be considered as having
not been successfully received even if some fragments were
successfully received. The recipient may respond with a compressed
BA, in response to an eliciting A-MPDU that contains fragments. In
the compressed BA, each bit in the BA Bitmap indicates the receipt
status of either a fragment of the MSDU or the full MSDU. According
to certain aspects, A-MSDUs may be carried, without fragmentation,
within a single QoS data frame.
[0106] A STA may be configured to support concurrent reception of
fragments of some number of transmissions, for example, at least 3
MSDUs or MMPDUs. In some cases, however, a STA receiving more than
three fragmented frames may experience a significant increase in
the number of frames discarded. Therefore, the STA may be
configured to maintain a Receive Timer for each MSDU/MMPDU being
received (e.g., min. 3), and fragments may be discarded if the
timer exceeds a specified value (e.g., a
dot11MaxReceiveLifetime).
[0107] As noted above, there may be tradeoffs to consider when
deciding whether or not to use fragmentation. For example, in some
cases, fragments may not be allowed to be sent in A-MPDUs, except
when VHT Single MPDUs. Further, in such an exceptional case,
fragments may only be allowed for those TIDs for which an
HT-immediate or HT-delayed Block Ack session is not configured.
Fragmentation may be beneficial because it may increase reliability
when channel characteristics/OBSS activity limit reception
reliability, may increase medium efficiency in consideration of the
available duration of granted TXOPs, and may allow efficient use of
the allocated resources in an MU transmission. However, in some
cases, fragmentation may lead to an increased number of MSDUs being
discarded. For example, an MSDU may be dropped when the receive
MSDU timer expires, even if only one fragment is missing. This may
lead to increased memory requirements at the transmitter and
receiver as the transmitter and receiver needs to keep track of the
payload contents and length for each fragment and partial-state
operation during the Block Ack session may not be employed by the
receiver. Fragmentation may also lead to an increase in overhead,
as each fragment may require its own A-MPDU/MAC/Security headers
(e.g., fragmenting 1500 Bytes in 16 fragments could add at least
450 Bytes of overhead).
[0108] In some cases, devices may negotiate the use of
fragmentation during a block acknowledgement (BA) setup procedure.
In such cases, an Add Block Acknowledgement (ADDBA) Extension IE in
an ADDBA Request and/or response may indicate the use of
fragmentation. For example, in such case, an originator may set a
No-Fragmentation field in ADDBA Extension element of ADDBA Request
to indicate certain parameters.
[0109] FIG. 11 illustrates an example of such an ADDBA Extension
element format 1100 that may be included in an ADDBA request or
response. As illustrated, the format 1100 may have a
Fragmentation/No-Fragmentation Field 1110. In some cases, this
field may be set to a value to indicate whether or not an apparatus
intends to transmit fragments (e.g., 0 to indicate it intends to
transmit fragments, and to 1 to indicate it does not intend to
transmit fragments).
[0110] In some cases, the recipient (or originator) may
additionally specify (e.g., as part of a negotiation) various other
fragmentation parameters. For example, a recipient may specify a
maximum number of fragmented MSDUs (F-MSDUs) that can be supported
concurrently (with fragments for each tracked concurrently). As
illustrated, this value may be specified in a field 1120 (e.g.,
represented as 6 bits) containing the maximum number of concurrent
fragmented MSDU/MMPDUs that are supported. This parameter may
determine how many bits in the BA Bitmap will be maintained at full
state by the receiver. The recipient may also specify the receive
timer (e.g., represented as 8 bits in a field 1130 of a response)
that represents a period after which fragments are discarded (e.g.,
further attempts to reassemble a fragmented MMPDU or MSDU are
terminated). This parameter may help control memory overhead, by
limiting how long full state is maintained for a given fragmented
MSDU. In some cases, a dynamic fragmentation field (e.g.,
represented by a single bit in a field of the response) may
indicate the dynamic fragmentation mode (e.g., "0" to indicate
support for up to 2 dynamic length fragments per MSDU/MMPDU, or "1"
to indicate support for up to 16 dynamic length fragments per
MSDU/MMPDU).
[0111] In some cases, various other parameters related to
fragmentation may also be negotiated. As an example, a (receiving)
device may indicate allowance (of an originator) to fragment
A-MSDUs. For example, during negotiation, a receiving device may
use a bit to indicate whether the receiving device supports
reception of fragmented A-MSDUs. In some cases, a receiving device
may also specify a minimum length of fragments during negotiation.
In such cases, all fragments but for a last fragment may be
required to be at least the specified minimum length.
[0112] In some cases, what may be considered a relatively
simplified version of a fragmentation mechanism may also be used.
In this case, peer STAs may use a baseline fragmentation mechanism
and may negotiate a baseline Block Ack mechanism where the
negotiation parameters described above are to be applied.
[0113] In some cases, a transmitter may be allowed to aggregate at
most one fragment in an A-MPDU. In such cases, on the receiver
side, upon reception of an A-MPDU that contains a single MPDU that
solicits a response, the receiving device may respond with an Ack
frame (regardless of whether the MPDU contains a fragment or a full
MSDU). On the other hand, upon reception of an A-MPDU containing
more than one MPDU that solicits a response, the receiving device
may respond with a BlockAck frame, wherein the BlockAck frame could
be a compressed BlockAck, a multi-TID BlockAck, multi-STA BlockAck
or a GCR BlockAck frame that additionally contains an indication
for indicating the receipt status of the fragment included in the
soliciting PPDU. For example, the receiving device may set a bit in
the BlockAck frame for a fragment contained in the A-MPDU that is
received successfully. Any reserved bit which is currently unused
may be used for this purpose (e.g., an unused bit of a Fragment
Number may be used for this purpose).
[0114] In certain embodiments the transmitter may include more than
one fragment in an A-MPDU, in which case the recipient may respond
with a control response frame that acknowledges the multiple
fragments according to the teachings herein.
[0115] Upon reception of a BlockAck Request (BAR), a receiving
device may respond with the appropriate response frame. For
example, the receiving device may respond with a compressed
BlockAck if no fragments have been received for a corresponding
BlockAck window. In some cases, the BAR itself may indicate that it
solicits a compressed BlockAck. In some cases, the receiving device
may respond with a basic (not compressed) BlockAck, for example, if
at least one fragment is received (or the BAR itself specifies a
basic BlockAck is solicited).
[0116] As noted above, during a fragment-enabled BA session, the
originator may fragment MSDUs and carry them in an A-MPDU. The
recipient may respond acknowledging the A-MPDU with a shortest BA
(e.g., the shortest BA frame may be the C-BlockAck frame). For
efficient use of allocated UL/DL resources, in some cases, one
fragment in an A-MPDU may be enough.
[0117] There may be trade-offs when allowing more than one fragment
per A-MPDU. For example, while more than one fragment per A-MPDU
may provide flexibility to fragment any MSDU in any number of
fragment per-TID, doing so may increase processing overhead. For
example, both recipient and originator may need to maintain a
Receive Timer for each MSDU (e.g., during which all fragments need
to be successfully received or they are flushed). In addition, the
recipient may need to store the payload for each fragment of each
MSDU that is fragmented as fragments are not delivered to upper
layers but stored locally until MSDU is derived. This approach may
also increase the likelihood of discarded MSDUs due to receive
timer expiration (e.g., even if only one fragment is missing) and
result in increased implementation complexity due to additional
fragmentation/defragmentation procedures, as well as increased
overhead as each added fragment requires its own MPDU
delimiter/MAC/security headers.
[0118] As illustrated in the example exchange 1200 of FIG. 12, in
some cases, an originator may decide to use fragmentation
"on-the-fly" whenever it determines fragmentation will result in
efficient use of resources. In the illustrated example, two MSDUs
1210 may not be fragmented (Data 1 and Data 2) while a third may be
fragmented (e.g., in up to 2 fragments for Dyn. Frag.=0 or up to 16
fragments for Dyn. Frag.=1). The first fragment 1220 (of Data 3
labeled Frag 3.0) may be used to efficiently fill the allocated
resource. In either case, there may be no length restriction for
any of the fragments. As noted above, in some cases, only one
fragment of an MSDU/MMPDU may be transmitted in the A-MPDU.
[0119] The rest of the fragments of the frame may be scheduled for
transmission in successive TXOPs. The Recipient may respond (using
resources of an UL allocation) to an eliciting frame that contains
a fragment with either of the following: an Ack frame if the
fragment is carried in a (VHT Single) MPDU or a compressed BlockAck
frame if the fragment is carried in an A-MPDU. Each bit in a bitmap
1240 may acknowledge receipt status of non-fragment MSDUs or of the
fragment of the MSDU that is carried in the eliciting A-MPDU. As
illustrated, the AP may send an ACK frame 1250 acknowledging
receipt of the BlockAck frame 1230.
[0120] Fragmentation in this manner may be beneficial as an
Originator may efficiently fill the allocated resources using the
first fragment to fill resource that cannot be filled with full
MSDU/MMPDU. Further, a receiver may not need significant memory to
support fragmentation (as only a limited amount of resources are
required to store fragments and the number of concurrently
supported fragmented transmissions may be limited).
[0121] In some cases, an MSDU may be fragmented in 2 parts, and
delivered in order which may be easily processed by receiver. For
example, the payload of the first fragment is stored in the same
buffer location of the MSDU. Upon reception of the second fragment,
the MSDU may be immediately constructed. Once constructed, the MSDU
may be sent to higher layer and the memory may be released for
other MSDUs. This may also reduce the number of discarded frames
due to fragmentation is reduced as: 2 fragments are expected to be
exchanged in a few TXOPs (e.g., 2 or more). This approach may make
it easier for the originator to make sure that Receive Timer does
not expire. The use of 2 fragments may also reduce overhead due to
fragmentation, which generally increases with the number of
fragments (with 2 fragments this overhead is minimal).
[0122] FIGS. 13A and 13B illustrate example exchanges 1300A and
1300B using fragmentation with 2-fragment BA exchanges, in
accordance with aspects of the present disclosure. As illustrated
in FIG. 13A, MSDUs 1210 may not be fragmented (Data 1 and Data 2),
while an MSDU for Data 3 may be fragmented. In this example, when
reception of a first fragment (a first fragment of Data3 labeled
Frag 3.0) is not acknowledged (e.g., is negatively acknowledged in
a compressed BA frame), the transmitter will transmit the FULL
original MPDU (Data 3) in the next TXOP. In some cases, a RETRY bit
may NOT be set for the full MPDU transmission (or re-transmission),
even if only a fragment of the MPDU was previously transmitted. As
illustrated in FIG. 13B, if the entire MPDU (for Data 3) does NOT
entirely fit in the TXOP, the transmitter may be allowed to
re-fragment the MPDU (with the first fragment of the re-fragmented
MPDU labeled as Frag 3.0') and determine a new boundary between the
two fragments (again, the RETRY bit may not be set).
[0123] FIGS. 14A and 14B illustrate other example exchanges 1400A
and 1400B using fragmentation with 2-fragment BA exchanges, in
accordance with aspects of the present disclosure. As illustrated
in FIG. 14A, after a first transmission, a BA is not successfully
received (e.g., it may be corrupted). In case of a re-transmission
where again MPDU for Data3 needs to be fragmented, the first
fragment (Frag 3.0) may be allowed to be resized (with the resized
fragment labeled as Frag 3.0') to make it smaller or larger, which
may help manage varying TXOP times. On the other hand, as
illustrated in FIG. 14B, if there is enough time in the TXOP, MPDU
3 may not need to be fragmented at all (and the entire MPDU for
Data 3 may be sent unfragmented).
[0124] As presented herein, fragmentation may be enabled for MU
operation using BA negotiation procedure between originator and
recipient. This approach may enable the recipient to signal its
capabilities to the transmitter and signal various parameters
(e.g., signaling Receive Timer for minimizing # of frames discarded
due to fragmentation, Max # of F-MSDUs for which full state BA
score is maintained, and Dynamic-length fragmentation selection).
This approach may help increase flexibility of fragmentation, by
allowing fragments to have dynamic lengths and carried in A-MPDUs,
while still using existing compressed BlockAck frames to
acknowledge frames during the fragment enabled BlockAck
session.
[0125] The various operations of methods described above may be
performed by any suitable means capable of performing the
corresponding functions. The means may include various hardware
and/or software component(s) and/or module(s), including, but not
limited to a circuit, an application specific integrated circuit
(ASIC), or processor. Generally, where there are operations
illustrated in figures, those operations may have corresponding
counterpart means-plus-function components with similar numbering.
For example, operations 700 and 800 illustrated in FIGS. 7 and 8
correspond to means 700A and 800A illustrated in FIGS. 7A and 8A,
respectively.
[0126] For example, means for transmitting may comprise a
transmitter (e.g., the transmitter unit 222) and/or the antenna(s)
224 of the access point 110 illustrated in FIG. 2, a transmitter
(e.g., the transmitter unit 254) and/or the antenna(s) 252 of the
user terminal 120 portrayed in FIG. 2, or the transmitter 310
and/or antenna(s) 316 depicted in FIG. 3. Means for receiving may
comprise a receiver (e.g., the receiver unit 222) and/or the
antenna(s) 224 of the access point 110 illustrated in FIG. 2, a
receiver (e.g., the receiver unit 254) and/or the antenna(s) 252 of
the user terminal 120 shown in FIG. 2, or the receiver 312 and/or
antenna(s) 316 depicted in FIG. 3. Means for processing, means for
generating, means for outputting, and/or means for determining may
comprise a processing system, which may include one or more
processors (e.g., capable of implementing the algorithm or
operations 700 and 800), such as the RX data processor 242, the TX
data processor 210, and/or the controller 230 of the access point
110 illustrated in FIG. 2, the RX data processor 270, the TX data
processor 288, and/or the controller 280 of the user terminal 120
illustrated in FIG. 2 or the processor 304 and/or the DSP 320
portrayed in FIG. 3.
[0127] In some case, rather than actually transmitting a packet (or
frame), a device may have an interface to output a packet for
transmission. For example, a processor may output a packet, via a
bus interface, to an RF front end for transmission. Similarly,
rather than actually receiving a packet (or frame), a device may
have an interface to obtain a packet received from another device.
For example, a processor may obtain (or receive) a packet, via a
bus interface, from an RF front end for reception.
[0128] According to certain aspects, such means may be implemented
by processing systems configured to perform the corresponding
functions by implementing various algorithms (e.g., in hardware or
by executing software instructions). These algorithms may include,
for example, an algorithm for receiving a plurality of PDUs, an
algorithm for determining whether each of the PDUs was successfully
received and whether each of the PDUs is associated with a
non-fragmented SDU or a fragmented SDU, and an algorithm for
outputting for transmission a shortened BlockAck frame comprising a
bitmap field indicating a receive status for the non-fragmented and
fragmented SDUs based on the determination. As another example,
these algorithms may include an algorithm for outputting a
plurality of PDUs for transmission, wherein each of the PDUs is
associated with a non-fragmented SDU or a fragmented SDU; an
algorithm for receiving a shortened BlockAck frame comprising a
bitmap field indicating a receive status for the non-fragmented and
fragmented SDUs; and an algorithm for processing the bitmap field
in the shortened BlockAck frame to determine whether the
non-fragmented and fragmented SDUs were successfully received.
[0129] As used herein, the term "determining" encompasses a wide
variety of actions. For example, "determining" may include
calculating, computing, processing, deriving, investigating,
looking up (e.g., looking up in a table, a database or another data
structure), ascertaining and the like. Also, "determining" may
include receiving (e.g., receiving information), accessing (e.g.,
accessing data in a memory) and the like. Furthermore,
"determining" may include resolving, selecting, choosing,
establishing and the like.
[0130] As used herein, a phrase referring to "at least one of" a
list of items refers to any combination of those items, including
single members. As an example, "at least one of: a, b, or c" is
intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any
combination with multiples of the same element (e.g., a-a, a-a-a,
a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or
any other ordering of a, b, and c).
[0131] The various illustrative logical blocks, modules and
circuits described in connection with the present disclosure 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 (PLD), 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 commercially available 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, a plurality of
microprocessors, one or more microprocessors in conjunction with a
DSP core, or any other such configuration.
[0132] The steps of a method or algorithm described in connection
with the present disclosure may be embodied directly in hardware,
in a software module executed by a processor, or in a combination
of the two. A software module may reside in any form of storage
medium that is known in the art. Some examples of storage media
that may be used include random access memory (RAM), read only
memory (ROM), flash memory, EPROM memory, EEPROM memory, registers,
a hard disk, a removable disk, a CD-ROM and so forth. A software
module may comprise a single instruction, or many instructions, and
may be distributed over several different code segments, among
different programs, and across multiple storage media. A storage
medium may be coupled to a processor such that the processor can
read information from, and write information to, the storage
medium. In the alternative, the storage medium may be integral to
the processor.
[0133] The methods disclosed herein comprise one or more steps or
actions for achieving the described method. The method steps and/or
actions may be interchanged with one another without departing from
the scope of the claims. In other words, unless a specific order of
steps or actions is specified, the order and/or use of specific
steps and/or actions may be modified without departing from the
scope of the claims.
[0134] The functions described may be implemented in hardware,
software, firmware, or any combination thereof. If implemented in
hardware, an example hardware configuration may comprise a
processing system in a wireless node. The processing system may be
implemented with a bus architecture. The bus may include any number
of interconnecting buses and bridges depending on the specific
application of the processing system and the overall design
constraints. The bus may link together various circuits including a
processor, machine-readable media, and a bus interface. The bus
interface may be used to connect a network adapter, among other
things, to the processing system via the bus. The network adapter
may be used to implement the signal processing functions of the PHY
layer. In the case of a user terminal 120 (see FIG. 1), a user
interface (e.g., keypad, display, mouse, joystick, etc.) may also
be connected to the bus. The bus may also link various other
circuits such as timing sources, peripherals, voltage regulators,
power management circuits, and the like, which are well known in
the art, and therefore, will not be described any further.
[0135] The processor may be responsible for managing the bus and
general processing, including the execution of software stored on
the machine-readable media. The processor may be implemented with
one or more general-purpose and/or special-purpose processors.
Examples include microprocessors, microcontrollers, DSP processors,
and other circuitry that can execute software. Software shall be
construed broadly to mean instructions, data, or any combination
thereof, whether referred to as software, firmware, middleware,
microcode, hardware description language, or otherwise.
Machine-readable media may include, by way of example, RAM (Random
Access Memory), flash memory, ROM (Read Only Memory), PROM
(Programmable Read-Only Memory), EPROM (Erasable Programmable
Read-Only Memory), EEPROM (Electrically Erasable Programmable
Read-Only Memory), registers, magnetic disks, optical disks, hard
drives, or any other suitable storage medium, or any combination
thereof. The machine-readable media may be embodied in a
computer-program product. The computer-program product may comprise
packaging materials.
[0136] In a hardware implementation, the machine-readable media may
be part of the processing system separate from the processor.
However, as those skilled in the art will readily appreciate, the
machine-readable media, or any portion thereof, may be external to
the processing system. By way of example, the machine-readable
media may include a transmission line, a carrier wave modulated by
data, and/or a computer-readable storage medium with instructions
stored thereon separate from the wireless node, all of which may be
accessed by the processor through the bus interface. Alternatively,
or in addition, the machine-readable media, or any portion thereof,
may be integrated into the processor, such as the case may be with
cache and/or general register files.
[0137] The processing system may be configured as a general-purpose
processing system with one or more microprocessors providing the
processor functionality and external memory providing at least a
portion of the machine-readable media, all linked together with
other supporting circuitry through an external bus architecture.
Alternatively, the processing system may be implemented with an
ASIC (Application Specific Integrated Circuit) with the processor,
the bus interface, the user interface in the case of an access
terminal), supporting circuitry, and at least a portion of the
machine-readable media integrated into a single chip, or with one
or more FPGAs (Field Programmable Gate Arrays), PLDs (Programmable
Logic Devices), controllers, state machines, gated logic, discrete
hardware components, or any other suitable circuitry, or any
combination of circuits that can perform the various functionality
described throughout this disclosure. Those skilled in the art will
recognize how best to implement the described functionality for the
processing system depending on the particular application and the
overall design constraints imposed on the overall system.
[0138] The machine-readable media may comprise a number of software
modules. The software modules include instructions that, when
executed by an apparatus such as a processor, cause the processing
system to perform various functions. The software modules may
include a transmission module and a receiving module. Each software
module may reside in a single storage device or be distributed
across multiple storage devices. By way of example, a software
module may be loaded into RAM from a hard drive when a triggering
event occurs. During execution of the software module, the
processor may load some of the instructions into cache to increase
access speed. One or more cache lines may then be loaded into a
general register file for execution by the processor. When
referring to the functionality of a software module below, it will
be understood that such functionality is implemented by the
processor when executing instructions from that software
module.
[0139] If implemented in software, the functions may be stored or
transmitted over as one or more instructions or code on a
computer-readable medium. Computer-readable media include 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 computer. By way of example, and not limitation, such
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 in the form of instructions or data
structures and that can be accessed by a computer. 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 (IR), 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.RTM. disc where disks usually
reproduce data magnetically, while discs reproduce data optically
with lasers. Thus, in some aspects computer-readable media may
comprise non-transitory computer-readable media (e.g., tangible
media). In addition, for other aspects computer-readable media may
comprise transitory computer-readable media (e.g., a signal).
Combinations of the above should also be included within the scope
of computer-readable media.
[0140] Thus, certain aspects may comprise a computer program
product for performing the operations presented herein. For
example, such a computer program product may comprise a
computer-readable medium having instructions stored (and/or
encoded) thereon, the instructions being executable by one or more
processors to perform the operations described herein. For certain
aspects, the computer program product may include packaging
material.
[0141] Further, it should be appreciated that modules and/or other
appropriate means for performing the methods and techniques
described herein can be downloaded and/or otherwise obtained by a
user terminal and/or base station as applicable. For example, such
a device can be coupled to a server to facilitate the transfer of
means for performing the methods described herein. Alternatively,
various methods described herein can be provided via storage means
(e.g., RAM, ROM, a physical storage medium such as a compact disc
(CD) or floppy disk, etc.), such that a user terminal and/or base
station can obtain the various methods upon coupling or providing
the storage means to the device. Moreover, any other suitable
technique for providing the methods and techniques described herein
to a device can be utilized.
[0142] It is to be understood that the claims are not limited to
the precise configuration and components illustrated above. Various
modifications, changes and variations may be made in the
arrangement, operation and details of the methods and apparatus
described above without departing from the scope of the claims.
* * * * *