U.S. patent application number 11/657544 was filed with the patent office on 2008-07-31 for method and apparatus for reliable multicast communication over wireless network.
Invention is credited to Christian Maciocco, Benjamin T. Metzler, Emily H. Qi.
Application Number | 20080181159 11/657544 |
Document ID | / |
Family ID | 39644857 |
Filed Date | 2008-07-31 |
United States Patent
Application |
20080181159 |
Kind Code |
A1 |
Metzler; Benjamin T. ; et
al. |
July 31, 2008 |
Method and apparatus for reliable multicast communication over
wireless network
Abstract
Method and apparatus for reliable multicast communication over
wireless network are provided. According to embodiments of the
invention, the method includes determining a priority category for
a multicast communication to be transmitted. The method includes
designating, for the multicast communication, one of the multicast
communication recipients as a leader based on the priority category
and multicast diagnostics information received from the multicast
communication recipients. The leader is assigned to transmit to the
multicast communication source an acknowledgment frame indicating
receipt of a multicast communication frame received from the
source.
Inventors: |
Metzler; Benjamin T.;
(Beaverton, OR) ; Qi; Emily H.; (Portland, OR)
; Maciocco; Christian; (Portland, OR) |
Correspondence
Address: |
Pearl Cohen Zedek Latzer, LLP
1500 Broadway, 12th Floor
New York
NY
10036
US
|
Family ID: |
39644857 |
Appl. No.: |
11/657544 |
Filed: |
January 25, 2007 |
Current U.S.
Class: |
370/312 |
Current CPC
Class: |
H04L 47/10 20130101;
H04L 1/1829 20130101; H04W 72/1242 20130101; H04L 47/14 20130101;
H04W 28/0205 20130101; H04L 12/1868 20130101; H04L 47/2441
20130101; H04L 2001/0093 20130101; H04L 47/15 20130101; H04W 4/06
20130101; H04L 1/1607 20130101; H04L 47/2433 20130101 |
Class at
Publication: |
370/312 |
International
Class: |
H04H 20/71 20080101
H04H020/71 |
Claims
1. A method comprising: determining a priority category for a
multicast communication to be transmitted; and designating, for the
multicast communication, one of a plurality of multicast
communication recipients as a leader to transmit to a multicast
communication source an acknowledgment frame indicating receipt of
a multicast communication frame received from the multicast
communication source, wherein designating the leader is based on
the priority category and multicast diagnostics information
received from one or more of said multicast communication
recipients.
2. The method of claim 1, wherein determining the priority category
is based on a reliability requirement for the multicast
communication.
3. The method of claim 1, wherein determining the priority category
comprises determining the priority category according to a
pre-determined set of rules.
4. The method of claim 1, wherein determining the priority category
comprises determining the priority category according to traffic
assignment on the application level.
5. The method of claim 1, wherein determining the priority category
comprises determining the priority category according to analysis
of the multicast diagnostics information.
6. The method of claim 1, wherein the multicast diagnostics
information comprises received multicast frame count information
received from one or more of said multicast communication
recipients.
7. The method of claim 1, wherein designating the leader comprises
designating the leader based on one of more performance metrics of
said multicast communication recipients.
8. The method of claim 7, further comprising: re-designating
another multicast communication recipient as a new leader if one or
more of said performance metrics associated with the new leader are
larger than a corresponding performance metric associated with a
previously designated leader and an hysteresis condition is
met.
9. The method of claim 7, further comprising: re-designating
another multicast communication recipient as a new leader if one or
more of said performance metrics associated with the new leader are
smaller than a corresponding performance metric associated with a
previously designated leader and an hysteresis condition is
met.
10. A communication device comprising: a transmitter to transmit a
multicast communication to a plurality of multicast communication
recipients; and a diagnostic unit to determine a priority category
for the multicast communication and to designate one of the
multicast communication recipients as a leader based on the
priority category and multicast diagnostics information received
from one or more of said multicast communication recipients,
wherein the leader being designated to transmit an acknowledgment
frame indicating receipt of a multicast communication frame
received from the communication device.
11. The communication device of claim 10, wherein the priority
category is based on a reliability requirement for the multicast
communication.
12. The communication device of claim 10, wherein the priority
category being determined according to a pre-determined set of
rules.
13. The communication device of claim 10, wherein the priority
category being determined according to traffic assignment on the
application level.
14. The communication device of claim 10, wherein the priority
category being determined according to analysis of the multicast
diagnostics information.
15. The communication device of claim 10, wherein the multicast
diagnostics information comprises received multicast frame count
information received from one or more of said multicast
communication recipients.
16. The communication device of claim 10, wherein the diagnostic
unit is to designate the leader based on one of more performance
metrics of said multicast communication recipients
17. The communication device of claim 10, wherein the diagnostics
unit is to re-designate another multicast communication recipient
as a new leader if one or more of said performance metrics
associated with the new leader are larger than a corresponding
performance metric associated with a previously designated leader
and an hysteresis condition is met.
18. The communication device of claim 10, wherein the diagnostics
unit is to re-designate another multicast communication recipient
as a new leader if one or more of said performance metrics
associated with the new leader are smaller than a corresponding
performance metric associated with a previously designated leader
and an hysteresis condition is met.
19. A wireless communication system comprising: at least one
communication device having: a dipole antenna to transmit wireless
communication signals; a transmitter to transmit a multicast
communication to a plurality of multicast communication recipients;
a diagnostic unit to determine a priority category for the
multicast communication and to designate one of the multicast
communication recipients as a leader based on the priority category
and multicast diagnostics information received from one or more of
said multicast communication recipients, wherein the leader being
designated to transmit an acknowledgment frame indicating receipt
of a multicast communication frame received from the communication
device.
20. The wireless communication system of claim 18, wherein the
communication device comprises a receiver to receive the
acknowledgment frame and the diagnostics information.
21. The wireless communication system of claim 18, wherein the
priority category is based on a reliability requirement for the
multicast communication.
22. An article comprising a machine-readable medium having
instructions stored thereon, which, when executed by a processor,
result in: determining a priority category for a multicast
communication to be transmitted; and designating, for the multicast
communication, one of a plurality of multicast communication
recipients as a leader to transmit to a multicast communication
source an acknowledgment frame indicating receipt of a multicast
communication frame received from the multicast communication
source, wherein designating the leader is based on the priority
category and multicast diagnostics information received from one or
more of said multicast communication recipients.
23. The article of claim 22, wherein the instructions when executed
further result in: determining the priority category according to
analysis of the multicast diagnostics information.
24. The article of claim 22, wherein the instructions when executed
further result in: designating the leader based on one of more
performance metrics of said multicast communication recipients.
Description
BACKGROUND OF THE INVENTION
[0001] Reliable multicast and broadcast of wireless communications
are gaining importance with the development in technology. In
organizations this may be exemplified by the fact multicast and
broadcast are becoming a required capability for delivery of live
conference, web training, and wireless network management. In home
networking, broadcast video streaming can be used for home
entertainment and gaming. In hospital environments, broadcast can
be used for commercial advertisement and television
broadcasting.
[0002] Existing communication protocols such as TEEE-Std 802.11,
1999 Edition (ISO/IEC 8802-11: 1999) standard do not support
reliable multicast/broadcast due to their inability to exchange
acknowledgment messages (ACK) with multiple recipients. Obtaining a
level of reliability in a multicast communication may be achieved
by designating for a given wireless network, a leader station to
respond to the multicast traffic with an ACK, thereby notifying the
multicast source that the packet was successfully delivered to at
least the leader. However, the higher reliability may cause a
longer delay or lower overall network throughput as the reliability
is achieved by the retransmission of packets in the network.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] The subject matter regarded as the invention is particularly
pointed out and distinctly claimed in the concluding portion of the
specification. The invention, however, both as to organization and
method of operation, together with objects, features and advantages
thereof, may best be understood by reference to the following
detailed description when read with the accompanied drawings in
which:
[0004] FIG. 1 is a schematic block diagram of an exemplary wireless
communication system according to some embodiments of the
invention; and
[0005] FIG. 2 is a schematic flow-chart diagram of a method of
multicast communication according to some embodiments of the
invention.
[0006] It will be appreciated that, for simplicity and clarity of
illustration, elements shown in the figures have not necessarily
been drawn to scale. For example, the dimensions of some of the
elements may be exaggerated relative to other elements for clarity.
Further, where considered appropriate, reference numerals may be
repeated among the figures to indicate corresponding or analogous
elements.
DETAILED DESCRIPTION OF THE INVENTION
[0007] In the following detailed description, numerous specific
details are set forth in order to provide a thorough understanding
of the invention. However, it will be understood by those of
ordinary skill in the art that the invention may be practiced
without these specific details. In other instances, well-known
methods, procedures, components, units and/or circuits have not
been described in detail so as not to obscure the invention.
[0008] Embodiments of the invention may provide a method for
dynamic adaptation of a leader node assignment for broadcast and
multicast traffic in a wireless network through the use of network
characterization and traffic type. According to embodiments of the
invention, the method may include assigning each multicast stream
an independent leader based on the characteristics of the traffic
stream and the distribution requirement for the particular type of
traffic.
[0009] Embodiments of the invention may be used in a variety of
applications. Some embodiments of the invention may be used in
conjunction with various devices and systems, for example, a
transmitter, a receiver, a transceiver, a transmitter-receiver, a
wireless communication station, a wireless communication device, a
wireless Access Point (AP), a modem, a wireless modem, a Personal
Computer (PC), a desktop computer, a mobile computer, a laptop
computer, a notebook computer, a tablet computer, a server
computer, a handheld computer, a handheld device, a Personal
Digital Assistant (PDA) device, a handheld PDA device, a network, a
wireless network, a Local Area Network (LAN), a Wireless LAN
(WLAN), a Metropolitan Area Network (MAN), a Wireless MAN (WMAN), a
Wide Area Network (WAN), a Wireless WAN (WWAN), devices and/or
networks operating in accordance with existing IEEE 802.11,
802.11a, 802.11b, 802.11e, 802.11g, 802.11 h, 802.11i, 802.11n,
802.16, 802.16d, 802.16e standards and/or future versions and/or
derivatives and/or Long Term Evolution (LTE) of the above
standards, a Personal Area Network (PAN), a Wireless PAN (WPAN),
units and/or devices which are part of the above WLAN and/or PAN
and/or WPAN networks, one way and/or two-way radio communication
systems, cellular radio-telephone communication systems, a cellular
telephone, a wireless telephone, a Personal Communication Systems
(PCS) device, a PDA device which incorporates a wireless
communication device, a Multiple Input Multiple Output (MIMO)
transceiver or device, a Single Input Multiple Output (SIMO)
transceiver or device, a Multiple Input Single Output (MISO)
transceiver or device, a Multi Receiver Chain (MRC) transceiver or
device, a transceiver or device having "smart antenna" technology
or multiple antenna technology, or the like. Some embodiments of
the invention may be used in conjunction with one or more types of
wireless communication signals and/or systems, for example, Radio
Frequency (RF), Infra Red (IR), Frequency-Division Multiplexing
(FDM), Orthogonal FDM (OFDM), Time-Division Multiplexing (TDM),
Time-Division Multiple Access (TDMA), Extended TDMA (E-TDMA),
General Packet Radio Service (GPRS), Extended GPRS, Code-Division
Multiple Access (CDMA), Wideband CDMA (WCDMA), CDMA 2000,
Multi-Carrier Modulation (MDM), Discrete Multi-Tone (DMT),
Bluetooth.RTM., ZigBee.TM., or the like. Embodiments of the
invention may be used in various other apparatuses, devices,
systems and/or networks.
[0010] Although the scope of the present invention is not limited
in this respect, the wireless communications technologies may
include radio frequency (RF) and infrared. Non-limiting examples of
RF wireless standards are protocols, such as, for example,
Bluetooth, IEEE-Std 802.11a, IEEE-Std 802.11b, 1999 edition,
IEEE-Std 802.11 g and HomeRF. Non-limiting examples of infrared
light signals are protocols, such as, for example, InfraRed Data
Association (IrDA) standard.
[0011] Although embodiments of the invention are not limited in
this regard, discussions utilizing terms such as, for example,
"processing," "computing," "calculating," "determining,"
"establishing", "analyzing", "checking", or the like, may refer to
operation(s) and/or process(es) of a computer, a computing
platform, a computing system, or other electronic computing device,
that manipulate and/or transform data represented as physical
(e.g., electronic) quantities within the computer's registers
and/or memories into other data similarly represented as physical
quantities within the computer's registers and/or memories or other
information storage medium that may store instructions to perform
operations and/or processes.
[0012] Although embodiments of the invention are not limited in
this regard, the terms "plurality" and "a plurality" as used herein
may include, for example, "multiple" or "two or more". The terms
"plurality" or "a plurality" may be used throughout the
specification to describe two or more components, devices,
elements, units, parameters, or the like. For example, "a plurality
of stations" may include two or more stations.
[0013] Although embodiments of the invention are not limited in
this regard, the term "multicast/broadcast" as used herein may
include, for example, multicast communication, broadcast
communication, wireless multicast communication, wired multicast
communication, wireless broadcast communication, wired broadcast
communication, multicast communication over the Internet or over a
global communication network, broadcast communication over the
Internet or over a global communication network, multicast
communication using TCP/IP, broadcast communication using TCP/IP,
web-cast communication (e.g., using the World Wide Web), and/or
other types of communication, e.g., non-unicast communication.
[0014] Reference is now made to FIG. 1, which schematically
illustrates a block diagram of an exemplary wireless communication
system 100 able to utilize multicast/broadcast communication
according to a demonstrative embodiment of the invention. System
100 may include one or more wireless communication stations, for
example, stations 101, 102, 103 and 104. System 100 may include a
wireless Access Point (AP) 105. Stations 101-104 may be referred to
as multicast/broadcast recipient devices and AP 105 may be referred
to as multicast/broadcast source device.
[0015] In some embodiments, stations 101-104 and AP 105 may
communicate using a shared access medium 190, for example, through
wireless communication links 191-195, respectively. In some
embodiments, stations 101-104 and AP 105 may be able to communicate
in accordance with a wireless communication standard or protocol,
for example, as defined by IEEE-Std 802.11, 1999 Edition (ISO/IEC
8802-11: 1999) standard, IEEE 802.16 standard, or the like.
[0016] According to some embodiments, for example, AP 105 may
transmit data intended to be received by more that one station
using multicast or broadcast. For example, AP 105 may use multicast
to transmit data to a group of stations of system 100, may use
broadcast to transmit data to substantially all possible listening
devices of system 100, may utilize a limited broadcast mechanism
based on a network segment, may utilize a direct broadcast
mechanism to transmit data to host devices of system 100, or the
like. In some embodiments, the multicast/broadcast may be over a
wireless mesh network, an ad-hoc network, a Basic Service Set
(BSS), an Independent BSS (IBSS), an infrastructure network, or the
like.
[0017] Station 101 may include, for example, a processor 111, an
input unit 112, an output unit 113, a memory unit 114, a storage
unit 115, and a modem having a transmitter 120 and a receiver 130.
Station 101 may optionally include other suitable hardware
components and/or software components. In some embodiments, the
components of station 101 may be enclosed in, for example, a common
housing, packaging, or the like.
[0018] Processor 111 may include, for example, a Central Processing
Unit (CPU), a Digital Signal Processor (DSP), a microprocessor, a
host processor, a controller, a plurality of processors or
controllers, a chip, a microchip, one or more circuits, circuitry,
a logic unit, an Integrated Circuit (IC), an Application-Specific
IC (ASIC), or any other suitable multi-purpose or specific
processor or controller. Processor 111 may, for example, process
signals and/or data transmitted and/or received by station 101.
[0019] Input unit 112 may include, for example, a keyboard, a
keypad, a mouse, a touch-pad, a stylus, a microphone, or other
suitable pointing device or input device. Output unit 113 may
include, for example, a Cathode Ray Tube (CRT) monitor or display
unit, a Liquid Crystal Display (LCD) monitor or display unit, a
screen, a monitor, a speaker, or other suitable display unit or
output device.
[0020] Memory unit 114 may include, for example, a Random Access
Memory (RAM), a Read Only Memory (ROM), a Dynamic RAM (DRAM), a
Synchronous DRAM (SD-RAM), a Flash memory, a volatile memory, a
non-volatile memory, a cache memory, a buffer, a short term memory
unit, a long term memory unit, or other suitable memory units or
storage units. Storage unit 115 may include, for example, a hard
disk drive, a floppy disk drive, a Compact Disk (CD) drive, a
CD-ROM drive, or other suitable removable or non-removable storage
units. Memory unit 114 and/or storage unit 115 may, for example,
store data transmitted and/or received by station 101.
[0021] Transmitter 120 may include, for example, a wireless Radio
Frequency (RF) transmitter able to transmit wireless RF signals,
e.g., through an antenna 121. Receiver 130 may include, for
example, a wireless RF receiver able to receive wireless RF
signals, e.g., through an antenna 131. In some embodiments, for
example, transmitter 120 and/or receiver 130 may be implemented
using a transceiver or a transmitter-receiver, using modem 125,
using a Network Interface Card (NIC), or one or more units able to
perform separate or integrated functions of transmitting and/or
receiving wireless communication signals, blocks, frames,
transmission streams, packets, messages and/or data.
[0022] Antenna 121 and/or antenna 131 may include an internal
and/or external RF antenna, for example, a dipole antenna, a
monopole antenna, an omni-directional antenna, an end fed antenna,
a circularly polarized antenna, a micro-strip antenna, a diversity
antenna, or any other type of antenna suitable for transmitting
and/or receiving wireless communication signals, blocks, frames,
transmission streams, packets, messages and/or data. In some
embodiments, optionally, antenna 121 and antenna 131 may be
implemented using a common or single antenna, e.g., a
transmit/receive antenna, or using a common set of transmit/receive
antennas.
[0023] In some embodiments, station 101 or one or more of stations
101-104 may include, for example, a management and control unit 141
and a diagnostics unit 142. Management unit 141 may perform
operations related to the multicast/broadcast communication, for
example, to exchange protocol messages with regard to "leader"
assignment, to manage the diagnostics unit 142, or to perform other
operations related to the multicast/broadcast communication in
accordance with some embodiments of the invention. The
multicast/broadcast management unit 141 and/or the diagnostics unit
142 may optionally be implemented, for example, using separate
components or units, using an integrated or combined unit, using
hardware component(s), using software component(s), as part of
processor 111, as part of modem 125, or the like.
[0024] Diagnostics unit 142 may perform analysis operations and may
generate diagnostics information to be transmitted to AP 105. The
diagnostic information generated by diagnostics unit 142 of station
101 may include, but not limited to, a received multicast/broadcast
frame count, received channel power indicator (RCPI) associated
with one or more received multicast/broadcast frames (e.g., with
the latest received or most recently received multicast/broadcast
frame), received signal-to-noise indicator (RSNI) associated with
one or more received multicast/broadcast frames (e.g., with the
most recently received multicast/broadcast frame) or quality
indicators associated with one or more received multicast frames or
with the incoming multicast/broadcast transmission. It should be
understood that embodiments of the invention are not limited to the
above-mentioned diagnostic information and that are metrics may be
reported by diagnostic unit 142 to AP 105.
[0025] In accordance with some embodiments of the invention, one or
more of stations 101-104 may transmit the diagnostics information
to AP 105, for example, periodically, at pre-defined time
intervals, upon demand, autonomously, when a pre-defined condition
is met, in response to a triggering event, or the like.
[0026] AP 105 may include, for example, antennae 160 and 170, a
processor 162, a transmitter 164 and a receiver 166. Although the
scope of the present invention is not limited in this respect,
antennae 160 and 170 may be omni-directional antennae, monopole
antennae, dipole antennae, end fed antennae, circularly polarized
antennae, micro-strip antennae, diversity antennae, GPS antennae or
the like. The two antennae may be different, e.g.; one may be a
dipole and the other end fed. In some embodiments, transmitter 164
may be coupled to antenna 160 and receiver 166 coupled to antenna
170. In other embodiments of this invention, transmitter 164 and
receiver 166 may both be coupled to a single antenna 160.
[0027] AP 105 may further include a multicast/broadcast management
and control unit 152 able to perform operations related to
management of the multicast/broadcast communication, for example,
to analyze the incoming multicast/broadcast diagnostics
information, to select or re-select leader station(s), to monitor
the incoming multicast/broadcast diagnostics information, to
monitor the received (or expected to be received)
multicast/broadcast acknowledgment frames, to activate or
de-activate (or otherwise modify) a multicast/broadcast
acknowledgment scheme, or the like. The multicast/broadcast
management unit 152 may optionally be implemented, for example,
using separate components or units, using an integrated or combined
unit, using hardware component(s), using software component(s), as
part of a processor or a modem of AP 105, or the like.
[0028] According to embodiments of the present invention, AP 105
may include a diagnostics unit 154 able to perform analysis and
characterization of a communication transmitted by AP 105 to a
plurality of stations via multicast or broadcast and to perform
analysis operations related to diagnostics information received
from one or more of stations 101-104, and the like. The analysis
may include determining the traffic reliability characterization of
the stream. For example, one transmission may be a commercial or
advertisement and it may be acceptable that most, but not all,
stations receive the traffic, and one may be an emergency multicast
message or network management message and it may be desirable that
a maximal number of stations receive the traffic.
[0029] The analysis and characterization may be done through
various means including, but not limited to, information technology
(IT) based set of rules, application level traffic assignment, and
an automated heuristic analysis of multicast traffic streams based
on established patterns and/or network conditions.
[0030] According to embodiments of the present invention,
diagnostics unit 154 may further select the most suitable
diagnostic metric for assigning a "leader" station according to the
type of the traffic stream transmitted by AP 105. For example, for
a multicast of a video stream a first diagnostic metric may be
selected and for a data stream a different diagnostic metric may be
selected. In some situations, it may be crucial the information be
transmitted as quickly as possible so that the data's latency is an
important measure. For other multicasts, accuracy may be most
important such that the frame loss rate and the signal's S/N ratio
may be the relevant metrics.
[0031] In accordance with some embodiments of the invention, for a
given multicast, diagnostic unit 154 may select a leader station
among all multicast/broadcast recipients according to the selected
diagnostic metric based on the characterization of the multicast
communication and the diagnostics information received from the
multicast/broadcast recipients (stations 101-104).
[0032] In some embodiments, one of stations 101-104 may be
designated (e.g., by AP 105) to operate as a "leader" station
(e.g., an acknowledger station, an acknowledgement sender station,
a confirming station, a designated station, an assigned station, a
selected station, a selectively designated station, an appointed
station, an elected station, a representative station, a
representative recipient station, or the like) for a selected
multicast, based on the metrics associated with that multicast.
[0033] In a demonstrative embodiment, for example, station 101 may
be designated as leader station, whereas stations 102-104 may not
be designated as leader stations--for a given multicast. The leader
station 101 may, for example, exchange protocol messages with AP
105. For example, when the leader station 101 receives a
multicast/broadcast frame from AP 105, the leader station 101 may
transmit an acknowledgment (ACK) packet or message to AP 105.
However, station 104 may be designated as leader for the next
multicast by the AP 105. This may be due, in part or completely, to
the fact different sets of metrics are used for the two
transmissions, to some physical change in the environment between
the two broadcasts, to the difference in the quality of the two
multicasts, some combination of factors, or other set of factors
not mentioned.
[0034] Reference is additionally made to FIG. 2, which is a
schematic flow-chart diagram of a method of multicast communication
according to some exemplary embodiments of the invention. This
procedure, as illustrated, may be performed for each multicast or
broadcast. Operations of the method may be implemented, for
example, by system 100 of FIG. 1, by any or all of stations 101-104
of FIG. 1, by AP 105 of FIG. 1, and/or by other suitable units,
devices, and/or systems.
[0035] As indicated at box 210, the method may include performing
analysis and characterization of a communication transmitted by AP
105 to a plurality of stations via multicast or broadcast and
determining the traffic reliability characterization of the stream.
This may, in some embodiments of the invention, include assigning a
priority category to each type of multicast/broadcast traffic.
[0036] As indicated at box 220, the method may include determining
an appropriate performance metric or metrics, based on the
characterization of a given multicast or broadcast, e.g.; emergency
broadcasts may be assigned the highest priority category and the
appropriate metric for such broadcasts may be the frame loss rate
(FLR). Once the performance metric has been selected, an initial
threshold value may be set, e.g.; for emergency broadcasts, the
leader may be the station with the lowest FLR and so the FLR
threshold may initially be set to 100% so that all responding
stations have a better--lower--FLR. In cases where the selected
performance metric is to be maximized, the initial value for the
threshold may be set at the minimal possible value so that all
responding stations have a better--higher--value.
[0037] Later, an initial leader may be selected by choosing the
station initially having the lowest FLR. Note that, if FLR is used,
the value each station--any or all of stations 101-104 in this
embodiment--actually reports to the AP 105 may be frame count. AP
105 may determine FLR from frame count because the AP 105 "knows"
how may frames were broadcast.
[0038] In some embodiments of the invention and for some metrics,
it may be desirable to set up an hysteresis condittion (text box
220). Otherwise, as some metrics may change very rapidly, the
designated leader may be constantly varying. Thus, rather than
setting the current performance threshold used for designating the
leader as the leader's prior performance, it may be beneficial to
adjust the threshold upward a certain percentage--from the leader's
prior metric, e.g.; if the metric is one to be maximized, the
threshold may be set at 20% greater than the leader's prior
measured performance and, if the metric is to be minimized, the
threshold may be set at 10% lower than the leader's prior
performance.
[0039] According to other embodiments of the invention, the
threshold may simply be set equal to the current leader's current
performance or the threshold may be a fixed value determined by the
type of multicast/broadcast or a requirement associated with the
multicast/broadcast.
[0040] As indicated at box 230, the method may optionally include,
for example, the AP 105 receiving multicast/broadcast diagnostics
information generated by stations 101-104 or other
multicast/broadcast recipients and calculating a selected
performance metric based on the received information, for each
reporting station. The diagnostics information may include, for
example, received multicast/broadcast frame count, received signal
strength indicator, packet error rate, signal to noise ratio,
measured latency, measured jitter, or other information and may or
may not be limited to metrics used in determining the chosen
performance metric for the multicast/broadcast.
[0041] AP 105 may calculate or estimate a different performance
metric or set of performance metrics for each type of
multicast/broadcast; for example, a FLR associated with a station,
an average FLR per station, an average received signal-to-noise
(SNR) per station, an average received signal strength per station
(RSSI), an average latency per station, an average jitter per
station, or the like, and/or any combination of the metrics
mentioned and any other sorts of metrics as may be deemed useful
for particular types of transmissions.
[0042] According to embodiments of the present invention, the
method may include, for example, assigning as a leader the
best-performing station associated the best-performance metric. AP
105 may then periodically analyze the diagnostics information
received from station 101-104 and based on comparison between the
performance metrics of the stations and the leader using the chosen
hysteresis value may decide whether a leader re-assignment is
required. If the leader's performance begins to drop significantly,
as pre-defined by a specific amount or percentage, some embodiments
of the invention may initiate a new leader selection loop, as
described in boxes 240-260.
[0043] As indicated by diamond block 240, if the selected
performance metric is one to be maximized, AP 105 may check whether
the performance metric of an unassigned station, for example
station 103, is greater than the performance metrics of the leader
and that the hysteresis condition is met. If so, then station 103
is assigned as the new leader by AP 105 (box 250). If not, then the
current leader station, station 101 may remain the leader (box
260).
[0044] Likewise, if the selected performance metric is one to be
minimized, AP 105 may check whether the performance metric of an
unassigned station, for example station 103, is smaller than the
performance metrics of the leader and that the hysteresis condition
is met. If so, then station 103 is assigned as the new leader by AP
105 (box 250). If not, then the current leader station, station 101
may remain the leader (box 260).
[0045] According to embodiments of the invention, each time the
decision is made to assign a leader and a potential leader has been
identified, the management and control unit 152 of AP 105 may
transmit a multicast/broadcast leader assignment request to
management and control unit 141 of station 101. In response,
management unit 141 may transmit a multicast/broadcast leader
assignment response to management unit 152 of AP 105. Diagnostics
unit 152 of AP 105 may transmit a multicast/broadcast diagnostics
information request to diagnostics unit 142 of station 101. In
response, diagnostics unit 142 of station 101 may transmit a
multicast/broadcast diagnostics information report (or other
suitable response) to the diagnostics unit 154 of AP 105.
[0046] In some embodiments, optionally, communication between AP
105 and/or station 101 (e.g., ACK packet or message, request to
designate as leader, response to the request to designate as
leader, or the like) may utilize a request-to-send (RTS) mechanism,
a clear-to-send (CTS) mechanism, a RTS/CTS mechanism, or other
suitable protocol mechanisms.
[0047] In some embodiments, leader station 101 may transmit a
notification to AP 105--at any time during
broadcasts/multicasts--to indicate that leader station 101 is about
to disconnect (e.g., move out, log off, or otherwise leave or exit)
from a wireless network common to AP 105 and leader station 101, or
that AP 105 has already disconnected from such wireless network. In
response, the AP 105 may designate another station as "leader" for
the remainder of the multicast, for example, based on diagnostics
information received from one or more of the stations 102-104 that
remain in the wireless network.
[0048] In some embodiments, a "leader"--based multicast/broadcast
acknowledgment scheme may, for example, increase the reliability of
multicast/broadcast communication, increase overall network
performance, increase overall network throughput. Some embodiments
may, for example, provide a link level reliability indicator to a
multicast/broadcast communication source. Embodiments of the
invention may allow additional and/or other benefits or
advantages.
[0049] Some embodiments of the invention may be implemented by
software, by hardware, or by any combination of software and/or
hardware as may be suitable for specific applications or in
accordance with specific design requirements. Embodiments of the
invention may include units and/or sub-units, which may be separate
of each other or combined together, in whole or in part, and may be
implemented using specific, multi-purpose or general processors or
controllers, or devices as are known in the art. Some embodiments
of the invention may include buffers, registers, stacks, storage
units and/or memory units, for temporary or long-term storage of
data or in order to facilitate the operation of a specific
embodiment.
[0050] Some embodiments of the invention may be implemented, for
example, using a machine-readable medium or article which may store
an instruction or a set of instructions that, if executed by a
machine, for example, by system 100 of FIG. 1, by station 101 of
FIG. 1, by processor 111 of FIG. 1, or by other suitable machines,
cause the machine to perform a method and/or operations in
accordance with embodiments of the invention. Such machine may
include, for example, any suitable processing platform, computing
platform, computing device, processing device, computing system,
processing system, computer, processor, or the like, and may be
implemented using any suitable combination of hardware and/or
software. The machine-readable medium or article may include, for
example, any suitable type of memory unit (e.g., memory unit 114 or
storage unit 115), memory device, memory article, memory medium,
storage device, storage article, storage medium and/or storage
unit, for example, memory, removable or non-removable media,
erasable or non-erasable media, writeable or re-writeable media,
digital or analog media, hard disk, floppy disk, Compact Disk Read
Only Memory (CD-ROM), Compact Disk Recordable (CD-R), Compact Disk
Re-Writeable (CD-RW), optical disk, magnetic media, various types
of Digital Versatile Disks (DVDs), a tape, a cassette, or the like.
The instructions may include any suitable type of code, for
example, source code, compiled code, interpreted code, executable
code, static code, dynamic code, or the like, and may be
implemented using any suitable high-level, low-level,
object-oriented, visual, compiled and/or interpreted programming
language, e.g., C, C++, Java, BASIC, Pascal, Fortran, Cobol,
assembly language, machine code, or the like.
[0051] Other operations or sets of operations may be used in
accordance with embodiments of the invention.
[0052] While certain features of the invention have been
illustrated and described herein, many modifications,
substitutions, changes, and equivalents may occur to those skilled
in the art. It is, therefore, to be understood that the appended
claims are intended to cover all such modifications and changes as
fall within the true spirit of the invention.
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