U.S. patent application number 10/880367 was filed with the patent office on 2009-03-19 for direct link relay in a wireless network.
This patent application is currently assigned to Globespan Virata Incorporated. Invention is credited to Menzo Wentink.
Application Number | 20090073913 10/880367 |
Document ID | / |
Family ID | 34556030 |
Filed Date | 2009-03-19 |
United States Patent
Application |
20090073913 |
Kind Code |
A9 |
Wentink; Menzo |
March 19, 2009 |
Direct link relay in a wireless network
Abstract
Disclosed herein are exemplary techniques for power conservation
in a wireless network. A wireless device identifies another
wireless device suitable to act as a relay node. Uplink information
is transmitted to the other wireless device, which is in turn
relayed to an access point for transmission to its destination.
Downlink information may be transmitted directly from the access
point to the wireless device. The use of a relay node may reduce
transmit power consumption as the relay node may be closer to, or
support a higher transmit rate, than the access point with which
the wireless device is associated.
Inventors: |
Wentink; Menzo; (Utrecht,
NL) |
Correspondence
Address: |
THOMAS, KAYDEN, HORSTEMEYER & RISLEY, LLP
600 GALLERIA PARKWAY, S.E.
STE 1500
ATLANTA
GA
30339-5994
US
|
Assignee: |
Globespan Virata
Incorporated
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20050094588 A1 |
May 5, 2005 |
|
|
Family ID: |
34556030 |
Appl. No.: |
10/880367 |
Filed: |
June 30, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10353391 |
Jan 29, 2003 |
6791962 |
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10880367 |
Jun 30, 2004 |
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60515701 |
Oct 31, 2003 |
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60388569 |
Jun 12, 2002 |
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Current U.S.
Class: |
370/315 |
Current CPC
Class: |
H04W 52/48 20130101;
Y02D 70/142 20180101; Y02D 70/326 20180101; H04W 88/04 20130101;
H04W 40/10 20130101; H04W 52/0258 20130101; H04W 52/04 20130101;
Y02D 30/70 20200801 |
Class at
Publication: |
370/315 |
International
Class: |
H04Q 7/00 20060101
H04Q007/00 |
Claims
1. In a wireless network comprising an access point communicating
with at least a first wireless device and a second wireless device,
a method comprising: receiving, at the first wireless device,
uplink information from the second wireless device via a direct
wireless link between the first and second wireless device, wherein
a destination of the uplink information includes a networked device
communicable with the access point; and relaying at least a portion
of the uplink information from the first wireless device to the
access point for transmission to the networked device.
2. The method as in claim 1, further comprising: receiving, at the
second wireless device, downlink information directly from the
access point, the downlink information having the second wireless
device as a destination.
3. The method as in claim 1, wherein relaying at least a portion of
the uplink information comprises: identifying, at the first
wireless device, the destination of the uplink information; and
transmitting at least a portion of the uplink information for
reception by the access point when the first wireless device is not
the destination of the uplink information.
4. The method as in claim 1, wherein the uplink information
received from the second wireless device includes at least one
frame having a header with a network address of the second wireless
device as a source address, a network address of the first wireless
device as an intermediate recipient address; and a network address
of the networked device as a destination address; and wherein
relaying at least a portion of the uplink information to the access
point includes modifying the header of the at least one frame to
have a network address of the access point as the intermediate
recipient address and relaying the at least one frame to the access
point.
5. The method as in claim 1, further comprising: determining that a
first transmit power necessary to transmit the uplink information
from the second wireless device to the first wireless device via
the direct wireless link is less than a second transmit power
necessary to transmit the uplink information from the second
wireless device directly to the access point.
6. In a wireless network comprising an access point communicating
with to a plurality of wireless devices, a method comprising:
identifying a first wireless device capable of relaying at least a
portion of uplink information from a second wireless device to the
access point, the uplink information having as a destination a
networked device communicable with the access point; establishing a
direct wireless link between the first wireless device and the
second wireless device; and transmitting at least a portion of the
uplink information from the second wireless device to the first
wireless device via the direct wireless link for relay to the
access point.
7. The method as in claim 6, further comprising relaying at least a
portion of the uplink information to the access point.
8. The method as in claim 6, wherein the uplink information from
the second wireless device includes at least one frame having a
header with a network address of the second wireless device as a
source address, a network address of the first wireless device as
an intermediate recipient address, and a network address of the
networked device as a destination address; and wherein relaying at
least a portion of the uplink information to the access point
includes modifying the header to have a network address of the
access point as the intermediate recipient address.
9. The method as in claim 6, further comprising: determining that a
first transmit power necessary to transmit the uplink information
from the second wireless device directly to the access point is
greater than a second transmit power necessary to transmit the
uplink information from the second wireless device to a selected
wireless device of the plurality of wireless devices.
10. The method as in claim 9, further comprising: receiving, at the
second wireless device, a relay node discovery frame from one or
more of the plurality of wireless devices, the relay node discovery
frame identifying the corresponding wireless device as available to
relay frames to the access point and having an associated transmit
power used to transmit the relay node discovery frame; determining
a path loss for the corresponding wireless device from the received
relay node discovery frame, wherein the path loss is based at least
in part on a difference between the transmit power associated with
the relay node discovery frame and a received power of the relay
node discovery frame; and selecting a wireless device as the first
wireless device based at least in part on a comparison of the path
losses.
11. The method as in claim 10, wherein the wireless device having
the lowest path loss is selected.
12. The method as in claim 6, wherein a first transmit power
necessary to transmit the uplink information from the second
wireless device to the first wireless device via the direct
wireless link is less than a second transmit power necessary to
transmit the uplink information from the second wireless device
directly to the access point.
13. A wireless device comprising: a transceiver adapted to receive
uplink information from another wireless device via a direct
wireless link with the other wireless device, wherein the uplink
information has as a destination a networked device communicable
with an access point; and the transceiver further adapted to
transmit at least a portion of the uplink information to the access
point for transmission to the networked device.
14. The wireless device as in claim 13, wherein means for relaying
at least a portion of the uplink information comprise: means for
identifying the destination of the uplink information; and wherein
the transceiver is adapted to transmit at least a portion of the
uplink information for reception by the access point when the
wireless device is not the destination of the uplink
information.
15. The wireless device as in claim 13, wherein the uplink
information received from the other wireless device includes at
least one frame having a header with a network address of the other
wireless device as a source address, a network address of the
wireless device as an intermediate recipient address; and a network
address of the networked device as a destination address; and
wherein the means for relaying at least a portion of the uplink
information to the access point includes means for modifying the
header of the at least one frame to have a network address of the
access point as the intermediate address.
16. The wireless device as in claim 13, wherein a first transmit
power necessary to transmit the uplink information from the other
wireless device to the wireless device via the direct wireless link
is less than a second transmit power necessary to transmit the
uplink information from the other wireless device directly to the
access point.
17. The wireless device as in claim 13, further comprising at least
one processor operably connected to the transceiver; and wherein:
the transceiver comprises executable instructions adapted to
manipulate the at least one processor to receive, via the
transceiver, the uplink information from the other wireless device
via the direct wireless link with the other wireless device; and
wherein the transceiver is further adapted for relaying at least a
portion of the uplink information to the access point comprise
executable instructions adapted to manipulate at least one
processor to relay, via the transceiver, at least a portion of the
uplink information to the access point for transmission to the
networked device.
18. The wireless device as in claim 13, further comprising means
for transmitting a relay node discovery frame for reception by one
or more other wireless devices, the relay node discovery frame
representing that the wireless device is available to relay frames
and including an indication of a transmit power used to transit the
relay node discovery frame.
19. A wireless device comprising: a transceiver; circuit means for
identifying another wireless device capable of relaying at least a
portion of uplink information from the wireless device to an access
point, the uplink information having a networked device operably
connected to the access point as a destination; communication means
for establishing a direct wireless link with the other wireless
device; and transmitter means for transmitting, via the
transceiver, the uplink information to the other wireless device
via the direct wireless link for relay to the access point.
20. The wireless device as in claim 19, wherein the means for
identifying the other wireless device include: Receiver means for
estimating a first transmit power necessary to transmit the uplink
information from the wireless device directly to the access point;
first circuit means for estimating a second transmit power
necessary to transmit the uplink information from the wireless
device to a selected wireless device of one or more other wireless
devices; and second circuit means for identifying the selected
wireless device as capable of relaying at least a portion of the
uplink information when the second transmit power is less than the
first transmit power.
21. The wireless device as in claim 20, further comprising:
receiver means for receiving a relay node discovery frame from one
or more other wireless devices, the relay node discovery frame
identifying the corresponding wireless device as available to relay
frames to the access point and including an indication of a
transmit power used to transmit the relay node discovery frame;
third circuit means for determining a path loss for at least one of
the one or more received relay node discovery frames, wherein the
path loss is based at least in part on a difference between the
transmit power indicated by the relay node discovery frame and a
received power of the relay node discovery frame; and fourth
circuit means for selecting a wireless device from the one or more
other wireless devices based at least in part on a comparison of
the path losses.
22. The method as in claim 21, wherein the other wireless device
having the lowest path loss is selected.
23. The method as in claim 19, wherein a first transmit power
necessary to transmit the uplink information from the wireless
device to the other wireless device via the direct wireless link is
less than a second transmit power necessary to transmit the uplink
information from the wireless device directly to the access
point.
24. The wireless device as in claim 19, further comprising at least
one processor operably connected to the transceiver, and wherein:
the means for receiving the uplink information comprise executable
instructions adapted to manipulate the at least one processor to
receive, via the transceiver, the uplink information from the other
wireless device via the direct wireless link with the other
wireless device; and the means for relaying at least a portion of
uplink information comprise executable instructions adapted to
manipulate the at least one processor to relay, via the
transceiver, at least a portion of the uplink information to the
access point for transmission to the networked device.
25. A wireless system comprising: a first wireless device; and a
second wireless device in communication with to an access point;
wherein the first wireless device is adapted to: identify the
second wireless device as capable of relaying at least a portion of
uplink information to the access point, the uplink information
having a networked device operably connected to the access point as
a destination; and transmit the uplink information to the second
wireless device via a direct wireless link between the first and
second wireless devices; and wherein the second wireless device is
adapted to relay at least a portion of the uplink information to
the access point for transmission to the networked device.
26. The wireless system as in claim 25, wherein the first wireless
device is further adapted to receive downlink information directly
from the access point, the downlink information having the first
wireless device as a destination.
27. The wireless system as in claim 25, wherein the second wireless
device is adapted to relay at least a portion of the uplink
information by: identifying, at the second wireless device, the
destination of the uplink information; and transmitting at least a
portion of the uplink information for reception by the access point
when the second wireless device is not the destination of the
uplink information.
28. The wireless system as in claim 25, wherein the uplink
information received from the first wireless device includes at
least one frame having a header with a network address of the first
wireless device as a source address, a network address of the
second wireless device as an intermediary address; and a network
address of the networked device as a destination address; and
wherein relaying at least a portion of the uplink information to
the access point includes modifying the header to have a network
address of the access point as the intermediary address.
29. The wireless system as in claim 25, wherein a first transmit
power necessary to transmit the uplink information from the first
wireless device to the second wireless device via the direct
wireless link is less than a second transmit power necessary to
transmit the uplink information from the first wireless device
directly to the access point.
30. The wireless system as in claim 25, wherein first wireless
device is adapted to identify the second wireless device by:
estimating a first transmit power necessary to transmit the uplink
information from the first wireless device directly to the access
point; estimating a second transmit power necessary to transmit the
uplink information from the first wireless device to a selected
wireless device of the plurality of wireless devices; and
identifying the selected wireless device as capable of relaying at
least a portion of the uplink information when the second transmit
power is less than the first transmit power.
31. The wireless system as in claim 25, wherein the second wireless
device is further adapted to transmit a relay node discovery frame
for reception by the first wireless device, the relay node
discovery frame identifying the second wireless device as available
to relay frames to the access point and including an indication of
a transmit power used to transmit the relay node discovery frame;
and wherein the first wireless device is further adapted to:
determine a path loss for the relay node discovery frame, wherein
the path loss is based at least in part on a difference between the
transmit power indicated by the relay node discovery frame and a
received power of the relay node discovery frame; and select the
second wireless device based at least in part on a comparison of
the path loss to path losses of one or more other wireless devices.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present invention claims benefit of U.S. Patent
Application No. 60/515,701 (Client Reference: GV 297; Attorney
Docket No.: 56162.000497) filed Oct. 31, 2003 and entitled
"Location Awareness in Wireless Networks," the entirety of which is
incorporated by reference herein.
[0002] U.S. patent application Ser. No. ______ (Client Reference:
GV 317; Attorney Docket No.: 56162.000517) filed concurrently
herewith and entitled "Event-Based Multichannel Direct Link," U.S.
patent application Ser. No. ______ (Client Reference: GV 319;
Attorney Docket No.: 56162.000519) filed concurrently herewith and
entitled "Piggyback Ack Link Margin Frames," U.S. patent
application Ser. No. ______ (Client Reference: GV 320; Attorney
Docket No.: 56162.000520) filed concurrently herewith and entitled
"Time-Scheduled Multichannel Direct Link," all claiming benefit of
U.S. Provisional Application No. 60/515,701 (Client Reference: GV
297; Attorney Docket No.: 56162.000497) filed Oct. 31, 2003, the
entireties of which are incorporated by reference herein.
[0003] The entirety of U.S. patent application Ser. No. 10/353,391
filed Jan. 29, 2003 and entitled "Direct Link Protocol In Wireless
Local Area" is also incorporated by reference herein.
FIELD OF THE INVENTION
[0004] The present invention relates generally to power management
in wireless networks and more particularly to economizing transmit
power consumption used by a wireless device.
BACKGROUND OF THE INVENTION
[0005] Various wireless standards, such as Institute of Electrical
and Electronics Engineers (IEEE) standards 802.11a/b/c/e/g/i
(referred to collectively as IEEE 802.11), provide for wireless
connectivity between wireless devices, such as, for example,
between a wireless station and an access point connected to an
infrastructure network. These wireless standards typically provide
processes for managing the power consumption of the wireless
devices in an attempt to minimize the power consumed by the
wireless devices, which at times may rely on battery sources for
power having a limited supply of power.
[0006] One technique frequently used to minimize the power
consumption of a wireless device includes increasing the
transmission rate (also referred to as the physical rate) of the
wireless device. It will be appreciated that increasing the
transmission rate reduces the power consumption as the time needed
to transmit information is reduced, thereby reducing the duration
that the antenna of the wireless device is active while
transmitting the signal representative of the information. However,
the maximum transmission rate supportable between wireless devices
may be limited for any number of reasons, such as, for example, the
distance between wireless devices, the presence of noise or other
interference, the individual capabilities of the wireless devices,
and the like.
[0007] In addition to, or instead of, implementing the maximum
supportable transmission rate between wireless devices, a reduction
in the transmit power used by a wireless device may be performed to
further reduce the power consumption of the wireless device. The
degree to which the transmit power of a transmitting wireless
station may be reduced generally is related to the link margin of a
receiving wireless device, where the link margin typically
represents a ratio of the actual received signal power to the
minimum received signal power desired or acceptable by the
receiving station. Thus, the transmitting station, in theory, could
reduce its transmit power by an amount up to the link margin of the
receiving wireless device without violating the minimum received
signal power requirement of the receiving wireless device. However,
even if taking the link margin into account, the degree to which
the transmit power may be reduced is still dependent largely on the
distance between the wireless devices.
[0008] Accordingly, improved techniques for economizing the
transmit power of a transmitting wireless device would be
advantageous.
SUMMARY OF THE INVENTION
[0009] The present invention mitigates or solves the
above-identified limitations in known solutions, as well as other
unspecified deficiencies in known solutions. A number of advantages
associated with the present invention are readily evident to those
skilled in the art, including economy of design and resources,
transparent operation, cost savings, etc.
[0010] The present invention is directed to a method including
receiving, at the first wireless device, uplink information from
the second wireless device via a direct wireless link between the
first and second wireless device, wherein a destination of the
uplink information includes a networked device communicable with
the access point, and relaying at least a portion of the uplink
information from the first wireless device to the access point for
transmission to the networked device in a wireless network.
[0011] A further aspect of the present invention is a method
including identifying a first wireless device capable of relaying
at least a portion of uplink information from a second wireless
device to the access point, the uplink information having as a
destination a networked device communicable with the access point
establishing a direct wireless link between the first wireless
device and the second wireless device, and transmitting at least a
portion of the uplink information from the second wireless device
to the first wireless device via the direct wireless link for relay
to the access point in a wireless network.
[0012] A further aspect of the present invention is a wireless
device including a transceiver adapted to receive uplink
information from another wireless device via a direct wireless link
with the other wireless device, wherein the uplink information has
as a destination a networked device communicable with an access
point, and the transceiver further adapted to transmit at least a
portion of the uplink information to the access point for
transmission to the networked device.
[0013] A further aspect of the present invention is a wireless
device including a transceiver, circuit means for identifying
another wireless device capable of relaying at least a portion of
uplink information from the wireless device to an access point, the
uplink information having a networked device operably connected to
the access point as a destination, communication means for
establishing a direct wireless link with the other wireless device;
and transmitter means for transmitting, via the transceiver, the
uplink information to the other wireless device via the direct
wireless link for relay to the access point.
[0014] A further aspect of the present invention is a wireless
system including a first wireless device and a second wireless
device in communication with to an access point. Also, the first
wireless device is adapted to identify the second wireless device
as capable of relaying at least a portion of uplink information to
the access point, the uplink information having a networked device
operably connected to the access point as a destination, and
transmit the uplink information to the second wireless device via a
direct wireless link between the first and second wireless devices.
Also, the second wireless device is adapted to relay at least a
portion of the uplink information to the access point for
transmission to the networked device.
[0015] Still further features and advantages of the present
invention are identified in the ensuing description, with reference
to the drawings identified below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The purpose and advantages of the present invention will be
apparent to those of ordinary skill in the art from the following
detailed description in conjunction with the appended drawings in
which like reference characters are used to indicate like elements,
and in which:
[0017] FIG. 1 is a schematic diagram illustrating an exemplary
wireless system in which various uplink relay techniques may be
advantageously implemented in accordance with at least one
embodiment of the present invention.
[0018] FIG. 2 is a schematic diagram illustrating the exemplary
wireless system of FIG. 1 in greater detail in accordance with at
least one embodiment of the present invention.
[0019] FIG. 3 is a flow diagram illustrating an exemplary method
for relaying uplink information in accordance with at least one
embodiment of the present invention.
[0020] FIG. 4 is a flow diagram illustrating an exemplary method
for identifying a suitable relay node in accordance with at least
one embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0021] The following description is intended to convey a thorough
understanding of the present invention by providing a number of
specific embodiments and details involving the minimization of the
transmit power used by a wireless device by relaying frames to an
access point via another wireless device. It is understood,
however, that the present invention is not limited to these
specific embodiments and details, which are exemplary only. It is
further understood that one possessing ordinary skill in the art,
in light of known systems and methods, would appreciate the use of
the invention for its intended purposes and benefits in any number
of alternative embodiments, depending upon specific design and
other needs.
[0022] For ease of illustration, the various techniques of the
present invention are discussed below in the context of IEEE
802.11-based wireless networking. However, those skilled in the
art, using the teachings provided herein, may advantageously
implement the disclosed techniques in other wireless networks.
Accordingly, reference to techniques and components specific to
IEEE 802.11, such as an 802.11-specific frame format, applies also
to the equivalent technique or component in other wireless network
standards unless otherwise noted.
[0023] Referring now to FIG. 1, an exemplary system 100 employing
one or more frame relay techniques disclosed herein is illustrated
in accordance with at least one embodiment of the present
invention. System 100 incorporates a general wireless network
topology described in IEEE 802.11 and other wireless standards
wherein one or more wireless devices are associated with at least
one access point 106. The wireless devices 101 and 103 include
devices enabled to communicate wirelessly using one or more
protocols. Such protocols may include, for example, the IEEE 802.11
protocols (802.11a/b/e/g/i), etc. Examples of wireless-enabled
devices may include notebook (or "laptop") computers, handheld
computers, desktop computers, workstations, servers, portable
digital assistants (PDAs), cellular phones, etc. In the illustrated
example, the wireless devices include a power conserving node (PCN)
102 and a relay node 104.
[0024] The access point 106 may be connected to an infrastructure
network 108 or other network, such as, for example, the Internet, a
local area network (LAN), a wide area network (WAN), and the like.
Thus, nodes 102 and 104 may communicate with one or more networked
devices on an infrastructure network via the access point 106.
Moreover, the nodes 102 and 104 may communicate with each other via
the access point 106 or, as discussed in greater detail below, via
a wireless direct link 110 between the nodes 102 and 104. Exemplary
techniques for establishing and maintaining a wireless direct link
are described, for example, in U.S. Pat. Application No.
60/515,701, the entirety of which is incorporated by reference
herein.
[0025] In conventional systems, a wireless device sends uplink
information (e.g., a set of one or more frames) to another
networked device by transmitting the uplink information to an
access point. The access point then transmits the uplink
information to its intended destination. If the intended network
device is within the basic service set (BSS) of the access point,
the access point may wirelessly transmit the frame to the network
device. Alternatively, if the networked device is located on the
infrastructure network to which the access point is connected, the
access point may provide the frame to the infrastructure network
for routing to the intended networked device.
[0026] However, by transmitting uplink information from a wireless
device directly to an access point, the transmitting wireless
device often consumes more power than necessary during the uplink
transmission. To illustrate, the distance between the wireless
device and the access point may require considerable transmit power
to successfully transmit the uplink information. Additionally, the
access point may have a lower maximum transmission rate than that
available to the wireless device. As a result, it may take longer
to transmit the uplink information, therefore consuming more power
in the process.
[0027] Accordingly, the present invention provides a technique for
reducing the transmit power of a transmitting wireless device. In
at least one embodiment, the PCN 102 identifies and selects a
suitable relay node 104 for use in relaying uplink information 122
(e.g., one or more frames) to the access point 106, where the relay
node 104 may be closer to the PCN 102, may have less interference,
and/or is capable of supporting a higher transmit rate than the
access point 106, thus reducing the transmit power consumed by the
PCN 102. After identifying and selecting a suitable relay node 104,
a direct wireless link 112 may be established between the PCN 102
and the relay node 104 and the direct wireless link 112 may be used
to provide the uplink information 122 to the relay node 104 for
relay to the access point 106. The relay node 104 may modify the
uplink information 122 (e.g., by changing media access control
(MAC) addresses in the frame headers) and transmit the modified
uplink information 124 to the access point 106 using, for example,
a conventional device-to-access point wireless link 112. However,
because conserving transmit power at the access point 106 typically
is not a serious issue and because the power consumed in receiving
downlink information 126 is substantially constant regardless of
the distance and/or transmit rate, the PCN 102 may receive the
downlink information 126 directly from the access point 106 via the
conventional wireless link 114. The downlink information 126 may
have the the PCN 102 as a destination. However, in certain
instances, it may be preferable to relay the downlink information
126 from the access point 106 to the PCN 102 via the relay node 104
or one or more other wireless device.
[0028] Thus, by transmitting uplink information 122 to a relay node
104 that is closer (or having less interference) than the access
point 106, or capable of supporting a higher transmit rate, the PCN
102 consumes less transmit power than if the uplink information 122
were to be transmitted directly to the access point 106 via a
conventional device-to-access point wireless link 112. The
exemplary relay techniques are described in greater detail with
reference to FIGS. 2-4.
[0029] Referring now to FIGS. 2-4, exemplary configurations of the
PCN 102 and relay node 104, as well as an exemplary method 300 of
their operation, are illustrated in accordance with at least one
embodiment of the present invention. Although PCN 102 is described
herein as the transmitting device and relay node 104 is described
as the relaying device, the PCN 102 may act as a relay node for
relay node 104 or another wireless device and the relay node may
act as a PCN. Accordingly, those skilled in the art will appreciate
that a wireless device may implement some or all of the features of
both the PCN 102 and the relay node 104 such that the wireless
device is enabled to both identify, select and use one or more
relay nodes to conserve transmit power, as well as relay uplink
information for another wireless device.
[0030] In the illustrated example of FIG. 2, the PCN 102 includes
at least a transceiver 204A for transmitting and/or receiving
signals, one or more processors 206A and protocol stacks 208A for
processing and otherwise preparing information for transmission via
the transceiver 204A, as well as for processing information
received via the transceiver 204A. The PCN 102 further may include
a power conservation module 210 for identifying and selecting a
suitable relay node (e.g., relay node 104) for relaying uplink
information 122, establishing and/or maintaining a direct link 110
with the identified relay node, and/or managing the transmission of
the uplink information 122 to the selected relay node via the
direct link 110. The power conservation module 210 may be
implemented as software, hardware, firmware, or a combination
thereof. To illustrate, the power conservation module 210 may be
implemented as a software component of the protocol stack 208A, as
a separate software program or module executed by the processor
206A, or as a software or hardware component implemented as part of
the transceiver 204A.
[0031] As with the PCN 102, the relay node 104 includes a
transceiver 204B for transmitting and/or receiving signals to and
from other wireless devices and a processor 206B and protocol stack
208B for processing received information and information to be
transmitted. The relay node 104 further may include a relay module
212 for relaying uplink information from the PCN 102, as well as
for identifying itself to the PCN 102 as a relay node as discussed
below with reference to FIG. 4. The relay module 212 may be
implemented as software, hardware, firmware, or a combination
thereof, and may be implemented as a part of the transceiver 204B,
the protocol stack 208B, a software program or module executed by
the processor 206B, as a separate hardware or software component,
and the like.
[0032] As noted above, a conventional wireless device typically
transmits uplink information directly to an access point. However,
the access point may be at a significant distance and/or may have a
relatively low supported receive rate. Thus, to economize power
consumption when transmitting the uplink information, in at least
one embodiment, the PCN 102 is adapted to identify a relay node
suitable to relay uplink information from the PCN 102 to the access
point 106 at step 302 of method 300 (FIG. 3). Generally, a relay
node is suitable if the transmission of uplink information 122 to
the relay node consumes less power at the PCN 102 than the
transmission of the uplink information 122 directly to access point
106. Factors which may be considered by the PCN 102 in determining
the suitability of a relay node include the distance/interference
between the PCN 102 and the relay node in comparison with the
distance/interference between the PCN 102 and the access point 106,
the maximum receive rate supported by the relay node in comparison
with the maximum receive rate supported by the access point 106
(subject to the maximum transmit rate supported by the PCN 102),
and the like. An exemplary method for identifying and selecting a
suitable relay node is discussed below with reference to FIG.
4.
[0033] Once a suitable relay node 104 is selected, a direct
wireless link 110 may be established between the PCN 102 and the
relay node 104 at step 304. Any of a variety of techniques for
establishing a direct wireless link may be implemented, such as by
using the Direct Link Protocol (DLP) technique described in U.S.
patent application Ser. No. 10/353,391 referred to above and
incorporated by reference above. The direct wireless link 110 may
be initiated by either the PCN 102 or the relay node 104.
[0034] At step 306, the uplink information 122 (FIG. 1) may be
transmitted to the relay node 104 via the direct wireless link 110.
For ease of discussion, the uplink information 122 is illustrated
as a data frame 222 including a header 224 and payload 232, where
the header 224 has, for example, a source address field 226, an
intermediary address field 228 and a destination address field 230.
The address fields 226-230 may include any of a variety of address
formats used to route frames, such as, for example, a media access
control (MAC) address or an Internet Protocol (IP) address. In at
least one embodiment, the source address field 226, the
intermediary address field 228, and the destination address field
230 respectively include the address A of the PCN 102, the address
B of the relay node 104, and the address C of the networked device
for which the frame 222 is intended (i.e., the destination of the
frame 222). The networked device may include a device on the
network 108 or other network, another wireless device in the BSS
serviced by the access point 106, and the like.
[0035] At step 308, the frame 222 is received by the transceiver
204B of the relay node 104 and provided to the processor 206B, the
protocol stack 208B and/or the relay module 212 for processing.
Part of this processing may include determining whether the relay
node 104 is the destination of the frame 222 or whether the relay
node 104 is to act as an intermediary for the frame 222.
Accordingly, the relay module 212 (or protocol stack 208B) may
compare the address in the destination address field 230 with the
address of the relay node 104. If the comparison reveals that the
relay node 104 is not the destination of the frame 222, the relay
node 104 may prepare to relay the frame 222 to the access point
106. As part of this processing, the relay module 212 may modify
the header 224 by replacing the address B of the relay node 104 in
the intermediary address field 228 with the address D of the access
point 106. At step 310, resulting modified header 234 and the
payload 232 may be transmitted to the access point 106 as a
modified frame 244 via the device-to-access point link 112. Upon
receipt of the modified frame 244, the access point 106 may process
the frame 244 as necessary and forward it to the intended networked
device (e.g., a device on network 108), as indicated by address C
in the destination address field 230.
[0036] Referring now to FIG. 4, an exemplary implementation of step
302 of method 300 (FIG. 3) for identifying a wireless device that
is suitable to act as a relay node for another wireless device is
illustrated in accordance with at least one embodiment of the
present invention. Step 302 begins at substep 402, the relay module
212 or one or more potential relay nodes 104 may initiate the
broadcast of a relay node discovery frame 214 (illustrated with
reference to FIG. 2). The relay node discovery frame 214 may
include a broadcast or multicast address M in destination address
field 216 and the address B of the relay node 104 in the source
address field 218. Moreover, the relay node discovery frame 214 may
include an indication of the transmit power (e.g., a value in
decibels (dB)) used to broadcast the frame 214, where this
indication may be stored in a header or payload 220 of the relay
node discovery frame 214. The payload 220 may further include an
indication of a maximum transmit rate supported by the relay node
104.
[0037] Upon receipt of a relay node discovery frame 214 from a
relay node 104, the power conservation module 210 of the PCN 102
may determine the received signal strength of the frame 214 as it
is received by the transceiver 204A. At substep 404, the power
conservation module 210 may determine a path loss associated with
the relay node 104, where the path loss represents the difference
between the transmit power of the relay node discovery frame 214
(as indicated in the frame 214) and the received signal strength.
An identifier associated with the relay node 104 (e.g., the address
of the relay node), its corresponding path loss and its maximum
supportable transmit rate may be added to a list or table
maintained by the power conservation module 210. The list or table
may be updated upon reception of subsequent relay node discovery
frames 214 from the relay node 104.
[0038] At substep 406, the power conservation module 210 determines
whether there is a relay node available to relay uplink information
122 and further whether it would require less transmit power to use
this relay node than it would to transmit the uplink information
122 directly to the access point 106. Accordingly, the power
conservation module 210 may determine and compare the quality of
link between the PCN 102 and the access point 106 to the quality of
one or more direct links (established or to be established) between
the PCN 102 and one or more relay nodes 104. In at least one
embodiment, the quality of a link is based at least in part on the
path loss, the maximum supported transmit rate, or a combination
thereof. If more than one relay node 104 is maintained in the list
or database of relay nodes, the power conservation module 210 may
select a relay node having the highest link quality for comparison
with the access point's link quality.
[0039] If the power conservation module 210 determine that less
transmit power would be consumed by transmitting directly to the
access point 106 at substep 406, the uplink information 122 may be
transmitted directly to the access point 106 via the link 114 (FIG.
1) at substep 408. However, if the power conservation module 210
determines that transmit power would be conserved by relaying
uplink information via a selected relay node 104, at substep 410 a
direct wireless link 110 may be established between the PCN 102 and
the selected relay node 104 (if not already established) and the
uplink information 122 may be transmitted to the selected relay
node 104 via the direct wireless link 110 for relay to the access
point 106 as described above.
[0040] Other embodiments, uses, and advantages of the invention
will be apparent to those skilled in the art from consideration of
the specification and practice of the invention disclosed herein.
The specification and drawings should be considered exemplary only,
and the scope of the invention is accordingly intended to be
limited only by the following claims and equivalents thereof.
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