Note: Descriptions are shown in the official language in which they were submitted.
CA 02588013 2011-02-10
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BROADCAST/MULTICAST DATA IN A WIRELESS NETWORK
BACKGROUND
Growth in demand for WLANs is driving the development of new technology to
provide higher throughput. To a greater extent this growth is due to the
increased number of
users and applications desiring wireless transmission and to a lesser extent
to the emergence
of new applications needing higher transmission rates along a single
connection between
two points. The former requires higher aggregate throughput. The latter
requires increased
link throughput. The present application relates to MAC-based approaches for
increasing
aggregate throughput of a wireless network (i.e. a WLAN or a wireless mesh
network) by
enabling the simultaneous transmission on multiple channels, and specifically
with the way
broadcast and multicast data can be transmitted.
The MAC protocol distinguishes between two logical channel functions, the
Control
Channel (CC) and the Data Channel (DC). Stations exchange control and
management
frames on the control channel. The data channels carry data traffic.
Reservations for
transmission on the various data channels are made by exchanging control
frames on the
control channel. This control channel is used by each node for time
reservations on data
channel(s) and for acknowledgements. The control channel does not change
dynamically
(fast).
Data channel(s) are the channels used by nodes to transmit data traffic. Each
node
may transmit always on the same data channel(s), or it may select a channel to
transmit on
demand (dynamic channel assignment).
As extensions of the legacy RTS and CTS messages, the CC- RTS and CC-CTS are
used to reserve a data channel for the time it takes to transmit a
Transmission Opportunity
(TXOP). A TXOP (transmit opportunity) is a sequence of frames transmitted
between a pair
of nodes following a single contention for the channel. A Source node is the
node initiating
the TXOP, and the Destination node is the node receiving the TXOP. Data
traffic can be
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transmitted only on a data channel that is idle. The particular data channel
selected for
transmission of the TXOP is indicated in a special field on the CC-RTS/CC-CTS.
A CC-RTS frame is the frame used by a node initiating a TXOP. A CC-CTS frame
is used by a node accepting a TXOP. If acknowledgement of receipt of
transmission is
desired, it can be sent either on the data channel or on the control channel.
An
acknowledgement on the control channel, known as the CC-ACK, identifies the
individual
frame in a sequence of frames that were received successfully (similar to
802.11e Group
Ack).
A node with frames to transmit to a neighbor sets its data radio to transmit
on a
permissible data channel, sends a CC-RTS on the control channel to the
destination node,
and waits for a CC-CTS, which contains the acceptance or denial of the channel
reservation
request for the selected/assigned data channel.
If the destination node receives the CC-RTS, it sends a CC-CTS. The CC-CTS
will
contain a zero in the Reservation Duration field if the destination node does
not accept the
reservation request in the CC-RTS. A CC-CTS is not sent if the Reservation
Duration field
or the Number of Frames field contains a zero in the CC-RTS.
If the destination node accepts the reservation request in the CC-RTS, the
destination
node sets a data radio to receive on the data channel assigned/selected by the
source node. If
the destination node receives the same CC-RTS in the SIFS plus tx time, it
sends another
CC-CTS and waits for a time interval equal to SIFS plus CC-CTS tx duration. If
the CC-
CTS has not arrived at the source node by the expiration of SIFS plus CC-RTS
tx duration
plus CC-CTS tx duration, it transmits within SIFS another CC-RTS on the
control channel.
If the CC-CTS is received within a time interval comprising the SIFS plus the
CC-
RTS tx duration plus the CC-CTS tx duration by the source node, and the
Reservation
Duration field has a zero value, the source node sends a CC-RTS to the
destination node
with the Reservation Duration field set to zero. If the CC-CTS is received
within a time
interval equal to the SIFS plus the CC-RTS tx duration plus the CC-CTS tx
duration by the
source node, and the Reservation Duration field has been changed to a longer
value, the
source node sends a CC-RTS to the destination node with the Number of frames
set to zero.
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If the CC-CTS has arrived within the time interval equal to the SIFS plus the
CC-RTS tx
duration plus the CC-CTS tx duration at the source node, and the Reservation
Duration field
has a non-zero value, the source node transmits the frame(s) in the TXOP.
The CC-RTS/CC-CTS exchange may be defined so that it can reserve multiple data
channels, or the control channel and one or more data channels, for the same
time interval.
The CCC protocol can be expanded to allow for several channels to be reserved
at once for
the communication between two nodes. For instance, the sending node may
reserve a data
channel and the control channel for the transmission data. The data may be
split into two
streams to be transmitted simultaneously to the destination node one two
independent radios.
This would double the data rate between two nodes. In this scenario, the node
needs two
radios. Alternatively, two data channels may be reserved at once by the
transmitting node.
The two channels may be adjacent and a single broader bandwidth radio would be
used to
transmit and receive. If the two channels are not adjacent, two independent
data radios
would each transmit a portion of the data.
Two multi-channel MAC protocols are examined. One protocol requires at least
two
radios per device: one radio, the 'control radio', is dedicated to the control
channel, and the
remaining radios, called 'data radios', are tuned to data channels. Whereas
the control radio
may be used for control and data traffic, only data traffic may be sent
through the data
radio(s). We refer to this protocol as the 'multi-radio protocol'. The nodes
in a wireless
network employing a multi-radio protocol are referred to as 'multi-radio
nodes'.
The second protocol does not require a node to have a dedicated control radio.
The
same radio is switched between control and data channels. The nodes in a
wireless network
employing a single-radio protocol are referred to as 'single-radio nodes'.
When both single-radio and multi-radio nodes comprise a wireless network,
referred
to as a 'mixed network', additional known measures can be taken to allow for
the co-
existence of the two types of nodes.
With the multi-radio protocol, each node maintains a channel-specific NAV to
avoid
collisions. The NAV tracks the length of time for which a control or data
channel is
reserved. The NAV is the time period the node must refrain from transmitting
on the
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CA 02588013 2011-02-10
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channel, and is updated when a node receives a reservation request or a
response to the
reservation request. The NAV of a data channel is based on the value of the
Reservation
Duration field of the CC-RTS/CC-CTS. NAV-setting frames received on the data
channels
also update the data channel NAVs.
With a single-radio protocol, it is not possible to maintain NAV solely based
on the
NAV setting frames received on the control and data channels because there is
no dedicated
radio on the control channel. To make up for the lost NAV information,
requirements to
release all channels periodically force the NAV of all channels (either
implicitly or
explicitly) to be reset to zero. For the same reason, the control channel and
any data
channels shared by both single-radio and multi-radio nodes must be released
periodically in
a mixed network.
SUMMARY
This invention addresses the problem of sending broadcast/multicast data to a
collection of nodes in a wireless network employing a multi-channel protocol.
With
wireless LANs that access a single channel, broadcast and multicast data are
simply sent on
that channel. Under a multi-channel MAC protocol, different options and
limitations exist.
With a multi-radio protocol, broadcast/multicast data may be sent on both the
control
channel and a data channel. With a single-radio protocol special precautions
must be taken
to ensure that all nodes will receive the broadcast/multicast data.
Embodiments of the invention provide mechanisms and techniques that provide a
method and apparatus for efficiently transmitting broadcast/multicast data in
a wireless
network.
In one particular embodiment of a method of transmitting broadcast/multicast
data in
a wireless network, the wireless network includes a plurality of multi-radio
nodes, and the
network further includes a control channel and at least one data channel. The
method
includes tuning one radio of each of the multi-radio nodes to the control
channel, and
transmitting the broadcast/multicast data to a plurality of nodes on the
control channel.
CA 02588013 2011-02-10
In another embodiment of a method of transmitting broadcast/multicast data in
a
wireless network, the wireless network includes a plurality of multi-radio
nodes, and the
network further includes a control channel and at least one data channel. The
method
includes tuning one radio of each of the multi-radio nodes to the control
channel, selecting a
5 data channel for broadcast/multicast data transmission, and transmitting
the
broadcast/multicast data on the selected data channel.
In another particular embodiment of a method of transmitting
broadcast/multicast
data in a wireless network, the wireless network having a control channel and
at least one
data channel, wherein the plurality of nodes includes at least one single-
radio node. The
method includes releasing, by all nodes of the network, the control channel
and all the data
channels accessible by single-radio nodes for a predetermined time at a start
of a period.
The method further includes tuning, by all nodes of the network, to the
control channel for
the predetermined time at the start of a period and assigning
broadcast/multicast
transmissions higher access priority; and thus transmitting
broadcast/multicast data before
unicast data can be transmitted on the control channel at the start of a
period P. The method
further includes assigning broadcast/multicast reservations higher access
priority; and thus
transmitting broadcast/multicast reservations before unicast reservations for
data channels
can be transmitted on the control channel at the start of a period P.
In another particular embodiment of a method of transmitting
broadcast/multicast
data in a wireless network, the network includes a plurality of multi-radio
nodes and/or
single-radio nodes, and the network further includes a control channel and at
least one data
channel that is accessible by both the single-radio and multi-radio nodes. The
method
includes releasing, by all nodes of the network, the control channel and the
data channels
accessible by the single-radio nodes at a predetermined time at a start of a
period. The
method further includes tuning, by all nodes of the network, to the control
channel at a
predetermined time at the start of a period. Additionally, the method includes
setting a timer
for a channel (NAY) which, if set, prevents the node from transmitting on the
channel, at the
predetermined time at a start of a period. The NAY of all data channels
accessible by
single-radio nodes is set to a constant value (CS) at the predetermined time
at a start of a
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period, and the NAV of the control channel is set to zero at the predetermined
time at a start
of a period. The method also includes not permitting transmission of unicast
data on the
control channel for a specified window (BW) at the start of a period.
Additionally, the
method includes reserving a data channel for a broadcast/multicast
transmission by
assigning higher priority to the transmission on the control channel of the
frames for such
reservation than the reservation frames of unicast data, thus enabling the
reservation
information to be received by all single-radio nodes before tuning their radio
to another
channel.
Other embodiments include a computer readable medium having computer readable
code thereon for transmitting broadcast/multicast data in a wireless network
including a
plurality of multi-radio nodes, the wireless network having a control channel
and at least one
data channel. The computer readable medium includes instructions for tuning
one radio of
each of said multi-radio nodes to the control channel and instructions for
transmitting
broadcast/multicast data to a plurality of nodes on the control channel.
Another embodiment includes a computer readable medium having computer
readable code thereon for transmitting broadcast/multicast data in a wireless
network, the
wireless network including a plurality of multi-radio nodes, and the network
further
including a control channel and at least one data channel. The computer
readable medium
includes instructions for tuning one radio of each of the multi-radio nodes to
the control
channel, instructions for selecting a data channel for broadcast/multicast
data transmission,
and instructions for transmitting the broadcast/multicast data on the selected
data channel.
Another particular embodiment includes a computer readable medium having
computer readable code thereon for transmitting broadcast/multicast data in a
wireless
network having a control channel and at least one data channel, wherein the
plurality of
nodes includes at least one single-radio node. The computer readable medium
includes
instructions for releasing, by all nodes of the network, the control channel
and all the data
channels accessible by single-radio nodes for a predetermined time at a start
of a period.
The computer readable medium further includes instructions for tuning, by all
nodes of the
network, to the control channel for the predetermined time at the start of a
period and
CA 02588013 2011-02-10
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assigning broadcast/multicast transmissions higher access priority; and thus
transmitting
broadcast/multicast data before unicast data can be transmitted on the control
channel at the
start of a period P. The computer readable medium further includes
instructions for
assigning broadcast/multicast reservations higher access priority; and thus
transmitting
broadcast/multicast reservations before unicast reservations for data channels
can be
transmitted on the control channel at the start of a period P.
In another particular embodiment a computer readable medium having computer
readable code thereon for of transmitting broadcast/multicast data in a
wireless network, the
network including a plurality of multi-radio nodes and/or single-radio nodes,
and the
network further including a control channel and at least one data channel that
is accessible
by both the single-radio and multi-radio nodes. The computer readable medium
includes
instructions for releasing, by all nodes of the network, the control channel
and the data
channels accessible by the single-radio nodes at a predetermined time at a
start of a period.
The computer readable medium further includes instructions for tuning, by all
nodes of the
network, to the control channel at a predetermined time at the start of a
period.
Additionally, the computer readable medium includes instructions for setting a
timer for a
channel (NAV) which, if set, prevents the node from transmitting on the
channel, at the
predetermined time at a start of a period. The NAV of all data channels
accessible by
single-radio nodes is set to a constant value (CS) at the predetermined time
at a start of a
period, and the NAV of the control channel is set to zero at the predetermined
time at a start
of a period. The computer readable medium also includes instructions for not
permitting
transmission of unicast data on the control channel for a specified window
(BW) at the start
of a period. Additionally, the computer readable medium includes instructions
for reserving
a data channel for a broadcast/multicast transmission by assigning higher
priority to the
transmission on the control channel of the frames for such reservation than
the reservation
frames of unicast data, thus enabling the reservation information to be
received by all single-
radio nodes before tuning their radio to another channel. In a particular
embodiment of this
invention, prioritization of the reservation frames for a broadcast/multicast
transmission on a
data channel can be achieved by various previously described methods.
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Still other embodiments include a node (a single-radio node or a multi-radio
node),
configured to process all the method operations disclosed herein as
embodiments of the
invention. In such embodiments, the node includes a memory system, a
processor,
communications interface in an interconnection mechanism connecting these
components.
The memory system is encoded with a process that provides transmitting
broadcast/multicast
data in a wireless network as explained herein that when performed (e.g. when
executing) on
the processor, operates as explained herein within the computerized device to
perform all of
the method embodiments and operations explained herein as embodiments of the
invention.
Thus any computerized device that performs or is programmed to perform
processing
explained herein is an embodiment of the invention.
Still another embodiment of the invention includes a Basic Service Set
(BSS)/mesh
wireless network. The wireless network includes an access point (AP) and a
plurality of
stations, at least one of the stations in communication with the AP via a
wireless
communication path including a control channel. Within the wireless network
the AP and
the at least one station communicate by way of a Common Control Channel (CCC)
protocol
wherein a BSS serving channel is utilized as the control channel for the CCC
protocol.
Other arrangements of embodiments of the invention that are disclosed herein
include software programs to perform the method embodiment steps and
operations
summarized above and disclosed in detail below. More particularly, a computer
program
product is one embodiment that has a computer-readable medium including
computer
program logic encoded thereon that when performed in a computerized device
provides
associated operations providing transmitting broadcast/multicast data in a
wireless network
as explained herein. The computer program logic, when executed on at least one
processor
with a computing system, causes the processor to perform the operations (e.g.,
the methods)
indicated herein as embodiments of the invention. Such arrangements of the
invention are
typically provided as software, code and/or other data structures arranged or
encoded on a
computer readable medium such as an optical medium (e.g., CD-ROM), floppy or
hard disk
or other a medium such as firmware or microcode in one or more ROM or RAM or
PROM
chips or as an Application Specific Integrated Circuit (ASIC) or as
downloadable software
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images in one or more modules, shared libraries, etc. The software or firmware
or other
such configurations can be installed onto a computerized device to cause one
or more
processors in the computerized device to perform the techniques explained
herein as
embodiments of the invention. Software processes that operate in a collection
of
computerized devices, such as in a group of data communications devices or
other entities
can also provide the system of the invention. The system of the invention can
be distributed
between many software processes on several data communications devices, or all
processes
could run on a small set of dedicated computers, or on one computer alone.
It is to be understood that the embodiments of the invention can be embodied
strictly
as a software program, as software and hardware, or as hardware and/or
circuitry alone, such
as within a data communications device. The features of the invention, as
explained herein,
may be employed in data communications devices and/or software systems for
such devices
such as those manufactured by Avaya Inc. of Lincroft, New Jersey.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing will be apparent from the following more particular description
of
preferred embodiments of the invention, as illustrated in the accompanying
drawings in
which like reference characters refer to the same parts throughout the
different views. The
drawings are not necessarily to scale, emphasis instead being placed upon
illustrating the
principles of the invention.
Figure 1 shows a multi-radio network environment having unicast traffic;
Figure 2 shows a multi-radio network environment having short multicast
traffic
transmitted on the control channel;
Figure 3 shows a multi-radio network environment having long multicast traffic
transmitted on the control channel;
Figure 4 shows a multi-radio network environment having long multicast traffic
transmitted on a traffic channel;
Figure 5 shows a multi-radio network environment having long multicast traffic
transmitted on a traffic channel;
CA 02588013 2011-02-10
Figure 6 shows a timing diagram of multiple periods for data transmission in a
network;
Figure 7 shows a timing diagram for three different traffic;
Figure 8 shows a single-radio network environment having short multicast
traffic
5 transmitted on the control channel;
Figure 9 shows a single-radio network environment having short multicast
traffic
transmitted on a traffic channel;
Figure 10 shows a single-radio network environment having short multicast
traffic
transmitted on a traffic channel;
10 Figure 11 shows a single-radio network environment having short
multicast traffic
transmitted on a traffic channel;
Figure 12 shows a single-radio network environment having long multicast
traffic
transmitted on the control channel;
Figure 13 shows a single-radio network environment having long unicast traffic
transmitted on a traffic channel;
Figure 14 shows a single-radio network environment having long multicast
traffic
transmitted on a traffic channel;
Figure 15 shows a single-radio network environment having long unicast traffic
transmitted on a traffic channel;
Figure 16 shows a flow diagram of a first particular embodiment of method of
transmitting multicast/broadcast data in a network having multi-radio nodes;
Figure 17 shows a flow diagram of a second particular embodiment of method of
transmitting multicast/broadcast data in a network having multi-radio nodes;
Figures 18A and 18B shows a flow diagram of a particular embodiment of method
of
transmitting multicast/broadcast data in a network having single-radio nodes;
Figure 19 shows a flow diagram of a particular embodiment of method of
transmitting multicast/broadcast data in a network having multi-radio nodes
and single-radio
nodes;
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CA 02588013 2011-02-10
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Figure 20 illustrates an example computer system architecture for a node that
performs transmitting of broadcast/multicast data in a wireless network in
accordance with
embodiments of the invention;
Figure 21 depicts a block diagram of a multi-channel BSS under CCC MAC using a
control channel and two data channels;
Figure 22 depicts a block diagram of a multi-channel BSS under CCC MAC using a
control channel and three data channels;
Figure 23 depicts a flow diagram of a particular embodiment of method of
transmitting data in a Basic Service Set (BSS)/Mesh wireless network; and
Figure 24 depicts a flow diagram of a particular embodiment of method of
transmitting data in an Independent Basic Service Set (IBSS)/Mesh wireless
network.
DETAILED DESCRIPTION
A method, apparatus and software for providing efficient transmission of
broadcast/multicast data in a network with single-radio nodes, multi-radio
nodes and a
combination of single-radio nodes and multi-radio nodes is presented.
Broadcast/multicast data is data sent to several destinations that can be
transmitted
simultaneously, thereby leaving channels available for use by others.
Broadcast data
comprises data that is sent to all node of the network, whereas multicast
traffic varies with
respect to the recipient list and amount of traffic. Examples of broadcast
data include
change of control channel, probe request, notice of power down and the like.
As stated
above, multicast data is data directed to multiple recipients and examples
include Internet
radio/music, group gaming, corporate data distribution and the like.
Broadcast/multicast
data can be either short data or long data. Different rules apply to the
transmission of
different types of multicast, and these rules vary with the protocol.
In order to properly perform transmission of broadcast/multicast data, a
control channel is
required. The node transmitting broadcast/multicast data must be able to
access a channel to
transmit the data, and the nodes must be tuned to that channel when data is
transmitted.
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CA 02588013 2011-02-10
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The common control channel provides a way for the transmitting and receiving
nodes to coordinate when and what channel a multicast transmission occurs on.
For multi-
radio nodes, all nodes have a radio dedicated to the common control channel.
Referring now to Figure 1, a timing diagram including multi-radio nodes
transmitting unicast data is shown. The timing diagram includes a control
channel and four
data traffic (MT) channels, designated traffic channels 1-4. The reservations
for the unicast
traffic (CC-RTS/CC-CTS) that occur on the control channel and allow for
efficient use of
the data channels is shown. Note that, for the unicast traffic there is very
little wasted
bandwidth, as the control channel and the data channels are nearly always
being utilized at
their maximum capacity.
For environments that utilize broadcast/multicast data, and which includes
multi-
radio nodes, all the nodes have at least two radios, with one of the radios
dedicated to the
common control channel. A reservation request is achieved with a CC-RTS
addressed to a
group, and no CC-CTS response is required. The destination address indicates
either a
group of nodes (multicast) or all the nodes associated with the network
(broadcast), and no
acknowledgement is required. Data (unicast/multicast/broadcast) can be
transmitted on
either traffic channels or the control channel. The choice of which channel to
use for data
transmission depends on MTXOP length. Transmission of long MTX0Ps on the
control
channel reduces utilization of MT channels as reservations for MT channels
cannot be made.
Short frames can be transmitted on control channel without reservation, or
with legacy
RTS/CTS. Figure 2 shows a timing diagram wherein a short broadcast of
multicast data
occurs on the control channel. The control radio is available to hear the
broadcast/multicast
data. All nodes have a radio dedicated to control channel. Short MTX0Ps (e.g.
network
signaling) can be transmitted on control channel without reservation, or with
legacy
RTS/CTS. Since the broadcast is a short broadcast, there is little or no
impact on the
reservations of the traffic channels, and the use of the available bandwidth
is efficient.
Referring now to Figure 3, transmission of long MTX0Ps on the control channel
reduces utilization of MT channels as reservations for MT channels cannot be
made. As
compared to Figure 2, the utilization of the data channels is not as optimal,
as the reservation
CA 02588013 2011-02-10
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13
of the channels has to wait until the multicast data transmission on the
control channel
completes. This reduces the efficiency of this type of operation as some
amount of
bandwidth is underutilized.
Referring now to Figures 4 and Figure 5, transmission of long MTX0Ps on a MT
channel leaves the control channel available for transmissions or reservations
for other MT
channels. In Figure 5,the node using traffic channel 3 has two data radios. To
transmit long
broadcast/multicast MTX0Ps on a MT channel, all nodes involved in transmission
must
have a MT radio/channel free. nodes that hear the reservation of a MT channel
for a
broadcast/multicast involving them tune a MT radio to the selected MT channel.
If a MT
radio is not available, a node that is involved in a broadcast/multicast
abandons the MTXOP
on a MT radio. To complete any interrupted MTX0Ps, new reservations are made
on the
control channel when the broadcast/multicast completes. As can be seen by
having long
multicast data transmission take place on a data channel instead of the
control channel the
efficiency is improved, since there is no need to wait before additional
reservations can be
made on the control channel for data channels.
Table 1 shows the preferred channel to use for data transmission depending on
the
type of data, the number of radios at the nodes, and the length of the data
transmission.
TABLE 1
MTXOP Length
Distribution # Radios
Long Short
2 or Control
Unicast more MT channel channel
Broadcast/ MT channel or
multicast Control
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A network may include only single-radio nodes, and may also be utilized for
providing broadcast/multicast data transmission. For this type of environment
all nodes
release all channels at the start of a period, referred to as a multi-channel
target beacon
transmission times (MTBTT) and tune to the control channel. All transmissions
must
complete by next MTBTT. At MTBTT, each node sets NAVs of all data channels
(DC) set
to predetermined constant value (CS) and sets the NAV of the common control
channel to
zero. All pending multicast data at a node is placed in a MTXOP. Figure 6
depicts a timing
diagram showing periods (P) each having a start point (MTBTT). Each period
also includes
a CS time period and a BW time period, explained in more detail below.
A multicast MTXOP will be transmitted either on the control channel or on a MT
channel. An node does not transmit a MTXOP containing data traffic on the
control channel
during a time period BW immediately following MTBTT. The multicast data MTXOP
is
transmitted first, before any reservations for MT channels can occur and
before radios are
retuned to MT channels. In a situation where there is no multicast data, CC-
RTS/CC-CTS
reservations for data traffic transmission start at CS following MTBTT. This
is shown in the
three scenarios depicted in Figure 7.
Figure 8 shows a timing diagram for a network having single-radio nodes
wherein a
short multicast is transmitted on the control channel. It can be seen that the
multicast data is
transmitted first, then followed by traffic transmission on the remaining data
channels and
on the control channel.
Figure 9 shows a timing diagram for a network having single-radio nodes
wherein a
short multicast is transmitted on a traffic channel. Again, the multicast data
is transmitted
first, then followed by data transmission on the control channel in the same
period and on
data channels during the next periods.
Figure 10 shows a timing diagram for a network having single-radio nodes
wherein
a short multicast is transmitted on a traffic channel without the use of the
BW (the window
of time where only reservations for MT channels are permitted on the control
channel).
Again, the multicast data is transmitted first, then followed by data
transmission on the
control channel in the same period and on data channels during the following
periods.
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CA 02588013 2011-02-10
Figure 11 shows a timing diagram for a network having single-radio nodes
wherein a
short multicast is transmitted on a traffic channel with the use of an
adjustable BW. The
multicast data is transmitted first, then followed by data transmission on the
control channel
in the same period and on data channels during the following periods.
5 Figure 12 shows a timing diagram for a network having single-radio
nodes wherein a
long multicast is transmitted on a traffic channel with the use of a BW. The
multicast data is
transmitted first, then followed by data transmission on the traffic channels
in the same
period and on the control channel and data channels during the following
periods. Because
the long broadcast/multicast is performed on the control channel, the
remaining nodes
10 cannot reserve data channels until after the multicast/broadcast
transmission completes.
Figure 13 shows a timing diagram for a network having single-radio nodes
wherein
a long unicast is transmitted on a traffic channel with the use of a BW. Other
unicast
transmissions occur on the control channel and on traffic channels.
Figure 14 shows a timing diagram for a network having single-radio nodes
wherein
15 a long multicast is transmitted on a traffic channel with the use of a
BW. The multicast data
is transmitted first, then followed by data transmission on the control
channel and data
channels in the same period and on the control channel and data channels
during the
following periods. Data traffic can occur on another traffic channel while the
multicast data
is being transmitted on a particular traffic channel.
Figure 15 shows a timing diagram for a network having single-radio nodes
wherein
a long broadcast is transmitted on a traffic channel with the use of a BW. The
broadcast
data is transmitted first, then followed by data transmission on the control
channel and data
channels during the following periods.
For unicast data, nodes are expected to hear a reservation if they have not
retuned
radio for another transmission since the last MTBTT. A reservation for unicast
data is made
with CC-RTS/CC-CTS on control channel. Acknowledgements for single-radio nodes
occur
either on traffic channel or on control channel (CC-ACK), and acknowledgements
for multi-
radio nodes occur on control channel (CC-ACK).
CA 02588013 2011-02-10
16
For the network having single-radio nodes, one broadcast/multicast MXTOP per
period is performed. All nodes hear the reservation, as the first MTXOP after
MTBTT is for
broadcast/multicast data. A reservation request is achieved with a CC-RTS
addressed a
group, no CC-CTS response required. The destination address indicates either a
group of
nodes (multicast) or all the nodes associated with the network (broadcast). No
acknowledgement is required
BW is the window ( a time period) where only reservations for MT channels are
permitted on the control channel. The transmission of data on the control
channel is limited
outside BW. nodes involved in a broadcast/multicast on a MT channel are not
allowed to
use MT channels until after next MTBTT. Such nodes can access the control
channel, but
only outside BW. To increase their access to a channel, such nodes can ignore
BW in the
period in which they are involved in a broadcast/multicast.
Table 2 shows the preferred channel to use for data transmission depending on
the
type of data, the number of radios at the nodes, and the length of the data
transmission.
TABLE 2
# Radios MTXOP Length
Distribution
Long Short
Unicast/ 1 Control
multicast MT channel channel
1 Control
Broadcast Control channel
A mixed network includes both single-radio nodes and multi-radio nodes. Nodes
may broadcast/multicast data on the control channel or on a shared MT channel
(channel
accessible by both single-radio and multi-radio nodes). All nodes release
control channel at
MTBTT. At MTBTT, nodes reset NAV of the common control channel to zero. All
nodes
CA 02588013 2011-02-10
17
release any shared MT channels at MTBTT. All single-radio nodes release all MT
channels
at MTBTT. At MTBTT, single-radio nodes reset NAVs of released MT channels to
CS. A
single-radio node shall not transmit a MTXOP containing data traffic on the
control channel
during a window BW immediately following MTBTT. All nodes can hear the
broadcast/multicast reservation. The reservation for a broadcast/multicast
will be made
before any single-radio node reservations for MT channels.
When broadcast/multicast is transmitted on control channel, multi-radio nodes
may
reserve MT channels any time, single-radio nodes may reserve MT channels after
broadcast/multicast ends. To transmit broadcast/multicast on a shared MT
channel, all
nodes must have one MT radio available. A single-radio node does not transmit
at the time
of a broadcast/multicast reservation. A multi-radio node may do one of the
following: if all
MT radios of a multi-radio node are busy, the transmission on one MT radio
must complete
by MTBTT, or the MTXOP on one MT radio of a multi-radio node is interrupted
when a
broadcast/ multicast reservation involving the node is made
Following the reservation, nodes involved in broadcast/multicast tune a radio
to
selected MT channel. Multi-radio nodes may reserve MT channels any time.
Single-radio
nodes not involved in a multicast may reserve MT channels after multicast
ends. Single-
radio nodes involved in multicast may not reserve MT channels before next
MTBTT.
Table 3 shows the preferred channel to use for data transmission depending on
the
type of data, the number of radios at the nodes, and the length of the data
transmission.
TABLE 3
# Radios MTXOP Length
. Distribution
Long Short
any
Unicast MT channel Control channel
Broadcast/ any MT channel or
multicast I control channel Control channel
-
CA 02588013 2011-02-10
18
Flow charts of particular embodiments of the presently disclosed methods are
depicted in Figures 16-19. The rectangular elements are herein denoted
"processing blocks"
and represent computer software instructions or groups of instructions.
Alternatively, the
processing blocks represent steps performed by functionally equivalent
circuits such as a
digital signal processor circuit or an application specific integrated circuit
(ASIC). The flow
diagrams do not depict the syntax of any particular programming language.
Rather, the flow
diagrams illustrate the functional information one of ordinary skill in the
art requires to
fabricate circuits or to generate computer software to perform the processing
required in
accordance with the present invention. It should be noted that many routine
program
elements, such as initialization of loops and variables and the use of
temporary variables are
not shown. It will be appreciated by those of ordinary skill in the art that
unless otherwise
indicated herein, the particular sequence of steps described is illustrative
only and can be
varied without departing from the spirit of the invention. Thus, unless
otherwise stated the
steps described below are unordered meaning that, when possible, the steps can
be
performed in any convenient or desirable order.
Referring now to Figure 16, a method 200 of transmitting broadcast/multicast
data in
a wireless network including a plurality of multi-radio nodes, the wireless
network having a
control channel and at least one data channel is shown. The method begins with
processing
block 202 which discloses tuning one radio of each of the multi-radio nodes to
the control
channel.
Processing block 204 states transmitting the broadcast/multicast data on the
control
channel. Processing block 206 recites the broadcast data is transmitted to all
nodes of the
wireless network and wherein the multicast data is transmitted to a plurality
of nodes of the
wireless network.
Referring now to Figure 17, a method 210 of transmitting broadcast/multicast
data in
a wireless network including a plurality of multi-radio nodes, the wireless
network having a
control channel and at least one data channel is shown. The method begins with
processing
CA 02588013 2011-02-10
19
block 212 which discloses tuning one radio of each of the multi-radio nodes to
the control
channel.
Processing block 214 recites selecting a channel for broadcast/multicast data
transmission. This may include, as recited in processing block 216 selecting a
channel
based on a length of the broadcast/multicast data, wherein broadcast/multicast
data having a
short length is broadcast on the control channel and wherein
broadcast/multicast data having
a long length is broadcast on one of the control channel and a data channel.
Processing continues with processing block 218 which discloses transmitting
the
broadcast/multicast data on the selected channel. Processing block 220 states
a node hearing
a reservation for a data channel for a broadcast/multicast data transmission
tunes a data radio
to the selected data channel. Processing block 222 recites assigning a higher
priority to the
transmission on the control channel of the frames for a reservation than the
reservation
frames of unicast data.
Referring now to Figures 18A and 18B, a particular embodiment of a method 250
of
providing broadcast/multicast data in a wireless network including a plurality
of single-radio
nodes, the wireless network having a control channel and at least one data
channel, is
shown. Processing begins with processing block 252 which discloses releasing,
by all nodes
of the network, the control channel and all the data channels accessible by
the single-radio
nodes for a predetermined time at a start of a period.
Processing block 254 states tuning, by all nodes of the network, to the
control
channel for the predetermined time at the start of a period. This is followed
by processing
block 256 which recites setting a timer for a channel (NAV) for all data
channels accessible
by single-radio nodes to a constant value (CS) beginning at the predetermined
time.
Processing block 258 discloses setting a timer (NAV) for the control channel
to zero at the
predetermined time.
Processing continues with processing block 260 which shows transmitting
reservations for unicast data after reservations for broadcast/multicast data
on the control
channel at the start of the period.
-- -
CA 02588013 2011-02-10
Processing block 262 discloses assigning broadcast/multicast transmissions
higher
access priority, and thus transmitting broadcast/multicast data before unicast
data can be
transmitted on the control channel at the start of a period P.
Processing block 264 states assigning broadcast/multicast reservations higher
access
5 priority, and thus transmitting broadcast/multicast reservations before
unicast data can be
transmitted on the control channel at the start of a period P.
Processing block 266 discloses the plurality of nodes includes at least one
single-
radio node and wherein the single-radio nodes can reserve data channels after
a
broadcast/multicast transmission completes. Processing block 268 discloses the
plurality of
10 nodes includes at least one multi-radio node and wherein the multi-radio
node can reserve a
data channel at any time.
Processing block 270 recites a node refraining from transmitting unicast data
traffic
on the control channel during a time period (BW) following a start of said
period, thus
enabling reservations for data channels to be transmitted on the control
channel before
15 unicast data traffic can be transmitted on the control channel at the
start of said period.
As described in processing block 272 the transmitting broadcast/multicast data
comprises transmitting broadcast/multicast data on one of the control channel
and a data
channel.
Processing block 274 discloses a node refraining from transmitting data
traffic on the
20 control channel during a time period (BW) following a start of the
period. Processing
block 276 states when there is no multicast/broadcast data to transmit, then
permitting
reservations for data traffic transmission beginning after the CS expires.
Referring now to Figure 19, a particular embodiment of a method 300 of
providing
broadcast/multicast data in a wireless network including a mix of single-radio
nodes and
multi-radio nodes, the wireless network having a control channel and at least
one data
channel, is shown. Processing begins with processing block 302 which discloses
releasing,
by all nodes of the network, the control channel and the at least one data
channel for a
predetermined time at a start of a period.
CA 02588013 2011-02-10
21
Processing block 302 states tuning, by all nodes of the network, to the
control
channel for the predetermined time at the start of a period. This is followed
by processing
block 304 which recites setting a timer for a channel (NAV) which, if set,
prevents the node
from transmitting on the channel, of all of the data channels accessible by
single-radio nodes
to a constant value (CS) beginning at the predetermined time. Processing block
308
discloses setting a timer for a channel (NAV) which, if set, prevents the node
from
transmitting on the channel, of the control channel to zero at the
predetermined time.
Processing continues with processing block 310 which discloses a node
refraining
from transmitting unicast data on the control channel during a time period
(BW) following a
start of the period. Processing block 312 recites reserving a data channel for
a
broadcast/multicast transmission by assigning higher priority to the
transmission on the
control channel of the frames for such reservation than the reservation frames
of unicast
data. This enables the reservation information to be received by all single-
radio nodes
before tuning their radio to another channel.
Figure 20 illustrates example architectures of a computer system 340 that is
configured as a node (single-radio or multi-radio). The node 340 may be any
type of
computerized system such as a personal computer, workstation, portable
computing device,
mainframe, server or the like. In this example, the system includes an
interconnection
mechanism 341 that couples a memory system 342, a processor 343, and a
communications
interface 344. The communications interface 344 allows the computer system 340
to
communicate with external devices or systems.
The memory system 342 may be any type of computer readable medium that is
encoded with an application 345-A that represents software code such as data
and/or logic
instructions (e.g., stored in the memory or on another computer readable
medium such as a
disk) that embody the processing functionality of embodiments of the invention
as explained
above. The processor 343 can access the memory system 342 via the
interconnection
mechanism 341 in order to launch, run, execute, interpret or otherwise perform
the logic
CA 02588013 2011-02-10
22
instructions of the applications 345-A in order to produce a corresponding
process 345-B.
In other words, the process 345-B represents one or more portions of the
application 345-A
performing within or upon the processor 213 in the computer system.
It is to be understood that embodiments of the invention include the
applications
(i.e., the un-executed or non-performing logic instructions and/or data)
encoded within a
computer readable medium such as a floppy disk, hard disk or in an optical
medium, or in a
memory type system such as in firmware, read only memory (ROM), or, as in this
example,
as executable code within the memory system 212 (e.g., within random access
memory or
RAM). It is also to be understood that other embodiments of the invention can
provide the
applications operating within the processor 213 as the processes. While not
shown in this
example, those skilled in the art will understand that the computer system may
include other
processes and/or software and hardware components, such as an operating
system, which
have been left out of this illustration for ease of description of the
invention.
A BSS network can utilize the CCC protocol even when the BSS includes a legacy
AP and one or more legacy stations. The BSS can include a collection of
stations wherein
one station is designated as an AP that talk to all other stations and is in
communication with
a Distribution Service System (DSS) which is the means used by the stations to
communicate outside the BSS. The serving channel of the BSS is utilized as the
control
channel and another channel (preferable a high throughput channel) is used as
a channel that
links the two stations (e.g. 802.11n stations). Alternately an Independent
Basic Service Set
(IBSS) can be used, the IBSS comprising a collection of stations that can
communicate with
each other as an ad-hoc network. The IBSS does not utilize an AP and
communication is
done in a peer-to-peer method. The IBSS established a channel that the
stations use to
communicate, and this channel is used as the control channel of the CCC
protocol. Two
stations can communicate with each other on a different channel using the
control channel to
signal to each other the channel to use for data transmissions.
Referring now to Figure 21, a first example of a multi-radio BSS/mesh wireless
network environment 400 utilizing the CCC protocol is shown. The environment
400
includes an Access Point (AP) 402, shown in communication with a WIFI Phone
404 by
CA 02588013 2011-02-10
23
way of a communication channel 420. In this example the communication channel
420 is a
Control Channel in accordance with the CCC protocol. Stations (e.g. WIFI phone
404)
reserve time on the control channel 420 by exchanging CC-RTS/CC-CTS on the
control
channel 420. AP 402 is also shown in communication with Laptop 412 by way of
the
control channel 420. The AP 402 can be a legacy AP utilizing the CCC protocol
to
communicate with other stations. Also utilizing the control channel for
communication sis
PDA 418, which is in communication with Desktop 416. The AP 402, WIFI phone
404 and
ODA 418 have one radio, and therefore use the control channel for making
reservations and
for exchanging data.
Also shown in environment 400 are other stations such as DVD Player 406, HDTV
408 and Camcorder 410. The devices have two radios, and use one radio for the
control
channel and the other radio for first data channel 422. DVD player 406, HDTV
408, and
Camcorder 422 reserve time on first data channel 422 by exchanging CC-RTS/CC-
CTS on
the control channel. Since the DVD player 406, HDTV 408, and Camcorder 422
have at
least two radios, one radio is tuned to the control channel and the other
radio or radios
transmits/receives data on the data channel. A device may have multiple data
radios for
higher node throughput. The Control channel can serve data channels of diverse
PHYs
(11a/g/n). Also shown is printer 414 which has two or more radios and as such
can
communicate with Laptop 412 and/or Desktop 416 by way of second data channel
424.
Referring now to Figure 22 a second example of a multi-radio BSS/mesh wireless
network environment 450 utilizing the CCC protocol is shown. The environment
450
includes an Access Point (AP) 452, shown in communication with a WIFI Phone
454 by
way of a communication channel 480. WiFi phone 454 is a single radio device.
In this
example the communication channel 480 is a Control Channel in accordance with
the CCC
protocol. Stations (e.g. WIFI phone 454) reserve time on the control channel
480 by
exchanging CC-RTS/CC-CTS on the control channel 480. Also having a single
radio is
Personal Digital Assistant (PDA) 468. PDA 468 is also in communication with
Desktop 466
CA 02588013 2011-02-10
24
by way of control channel 480. The AP 452 can be a legacy AP utilizing the CCC
protocol
to communicate with other stations. The WIFI phone 404 and PDA 418 have one
radio,
and therefore use the control channel for making reservations and for
exchanging data.
Also shown in environment 450 are other stations such as PVR 456, HDTV 482 and
Camcorder 460. The PVR is also in communication with AP 452 by way of first
data
channel 482. These devices have two radios, and use one radio for the control
channel and
the other radio for first data channel 482. PVR 456, HDTV 458, and Camcorder
460 reserve
time on first data channel 482 by exchanging CC-RTS/CC-CTS on the control
channel.
Since the PVR 456, HDTV 408, and Camcorder 422 have at least two radios, one
radio is
tuned to the control channel and the other radio or radios transmits/receives
data on the data
channel. A device may have multiple data radios for higher node throughput.
The Control
channel can serve data channels of diverse PHYs (11a/g/n).
Environment 450 additionally includes printer 464 which has two or more radios
and
as such can communicate with Laptop 462 and/or Desktop 466 by way of second
data
channel 484. Desktop 466 can communicate with AP 452 by way of third data
channel 486.
Third data channel 486 is also utilized by Multimedia games device 472 to
communicate
with AP 452 and is further utilized by Camera 474 for communication with
Desktop 466.
MP3 player 476 uses third data channel 486 for communications with Desktop
466. In this
environment, the WiFi phone 454 and the PDA 468 have a single radio, AP 452
has three
radios and the other devices have two radios.
Referring now to Figure 23, a particular embodiment of a method 500 of
transmitting
data in a Basic Service Set (BSS)/mesh wireless network, is shown. The method
begins
with processing block 502 which discloses providing an access point (AP). As
shown in
processing block 504 the AP comprises a legacy AP. As further shown in
processing block
506, the AP includes at least one radio.
Processing continues with processing block 508 which states providing a
plurality of
stations, at least one of the stations in communication with the AP, and at
least two of the
stations in direct communication with each other via a wireless communication
path
-
CA 02588013 2011-02-10
including a control channel. The term direct communication is used (here and
below) to
describe that the two station talk to each other without the intervention of
the AP.
Processing block 510 recites at least one the plurality of stations comprises
a legacy station.
Processing block 512 discloses wherein at least one of the plurality of
stations includes at
5 least one radio.
Processing block 514 states communicating between the at least two stations by
way
of a Common Control Channel (CCC) protocol wherein a BSS serving channel is
utilized as
the control channel for the CCC protocol. As shown in processing block 516 a
data channel
may be utilized by at least two of the group comprising the AP and the
plurality of stations.
10 Referring now to Figure 24,a particular embodiment of a method 550 of
transmitting
data in an Independent Basic Service Set (IBSS)/mesh wireless network is
shown. The
method 550 begins with processing block 552 which discloses providing a
plurality of
stations, at least one of the plurality of stations in direct communication
with another of the
plurality of stations via a wireless communication path including a control
channel. This
15 can include, as shown in processing block 554, wherein at least one of
the plurality of
stations comprises a legacy station. Further, as shown in processing block
556, at least one
of the plurality of stations includes at least one radio.
Processing continues with processing block 558 which recites communicating by
the
at least one of the plurality of stations by way of a Common Control Channel
(CCC)
20 protocol wherein the channel established by the IBSS for communication
is utilized as the
control channel for the CCC protocol. Processing block 560 discloses using a
data channel,
and wherein the data channel is utilized by at least two of the plurality of
stations.
Having described preferred embodiments of the invention it will now become
apparent to those of ordinary skill in the art that other embodiments
incorporating these
25 concepts may be used. Additionally, the software included as part of the
invention may be
embodied in a computer program product that includes a computer useable
medium. For
example, such a computer usable medium can include a readable memory device,
such as a
hard drive device, a CD-ROM, a DVD-ROM, or a computer diskette, having
computer
CA 02588013 2011-02-10
26
readable program code segments stored thereon. The computer readable medium
can also
include a communications link, either optical, wired, or wireless, having
program code
segments carried thereon as digital or analog signals. Accordingly, it is
submitted that that
the invention should not be limited to the described embodiments but rather
should be
limited only by the spirit and scope of the appended claims.
