U.S. patent application number 15/355495 was filed with the patent office on 2017-03-09 for devices for reduced overhead paging.
The applicant listed for this patent is QUALCOMM Incorporated. Invention is credited to Santosh Paul Abraham, Alfred Asterjadhi, Simone Merlin, Zhi Quan, Hemanth Sampath, Menzo Wentink.
Application Number | 20170070973 15/355495 |
Document ID | / |
Family ID | 46755109 |
Filed Date | 2017-03-09 |
United States Patent
Application |
20170070973 |
Kind Code |
A1 |
Merlin; Simone ; et
al. |
March 9, 2017 |
DEVICES FOR REDUCED OVERHEAD PAGING
Abstract
A method for reduced overhead paging by an access point is
described. The method includes assigning at least one paging
identifier to at least one station. The method also includes
partitioning a paging identifier space into paging identifier sets.
The method further includes generating a paging message based on at
least one of the paging identifier sets and the at least one paging
identifier. The method additionally includes sending the paging
message.
Inventors: |
Merlin; Simone; (San Diego,
CA) ; Sampath; Hemanth; (San Diego, CA) ;
Abraham; Santosh Paul; (San Diego, CA) ; Wentink;
Menzo; (Breukelen, NL) ; Quan; Zhi; (San
Diego, CA) ; Asterjadhi; Alfred; (San Diego,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM Incorporated |
San Diego |
CA |
US |
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|
Family ID: |
46755109 |
Appl. No.: |
15/355495 |
Filed: |
November 18, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13572427 |
Aug 10, 2012 |
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15355495 |
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61523033 |
Aug 12, 2011 |
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61552444 |
Oct 27, 2011 |
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61552661 |
Oct 28, 2011 |
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61591493 |
Jan 27, 2012 |
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61598200 |
Feb 13, 2012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 74/002 20130101;
H04W 88/02 20130101; H04W 88/08 20130101; H04W 84/12 20130101; H04W
76/11 20180201; H04W 74/02 20130101; H04W 68/02 20130101; H04W
74/06 20130101; H04W 68/025 20130101 |
International
Class: |
H04W 68/02 20060101
H04W068/02; H04W 74/00 20060101 H04W074/00; H04W 76/02 20060101
H04W076/02 |
Claims
1. A method for wireless communication by an access point,
comprising: determining a transmission schedule for a first
plurality of stations, wherein the first plurality of stations is
selected from a second plurality of stations; and determining a
duration of a reserved time interval that is reserved for
transmission.
2. The method of claim 1, wherein the paging message is associated
with at least one paging identifier of a plurality of paging
identifiers, wherein each of the plurality of paging identifiers is
associated with at least one station of the first plurality of
stations.
3. The method of claim 2, further comprising transmitting the
paging message to at least one of the second plurality of
stations.
4. The method of claim 1, further comprising communicating the
duration of the reserved time interval to at least one of the
second plurality of stations.
5. A method for wireless communication by an access point,
comprising: determining a reserved time interval; and setting the
reserved time interval for at least one paged station by setting a
network allocation vector.
5. A method for wireless communication by a station, comprising
determining a schedule for transmitting a polling message to an
access point, wherein the schedule is based on at least one paging
identifier.
7. The method of claim 6, wherein the schedule comprises a time at
which the station transmits the polling message.
8. The method of claim 6, wherein the schedule comprises a time at
which the station begins contention for a communication channel to
transmit the polling message.
9. The method of claim 6, wherein the schedule comprises a counter,
which the station counts down before transmission of a transmit
polling message while a communication channel is idle.
10. The method of claim 6, wherein the schedule is based on a hash
function of the station first paging identifier.
11. The method of claim 6, further comprising obtaining information
relative to a time interval reserved for transmission by a
plurality of stations selected from a set of stations.
12. The method of claim 11, further comprising performing a
determination as to whether to send a polling message to the access
point, wherein the determination is based on the first paging
identifier and the information relative to the reserved time
interval.
13. A method for wireless communication by a station, comprising:
obtaining information relative to a time interval reserved for
transmission by a plurality of stations selected from a second
plurality of stations; and performing a determination as to whether
to send a polling message to an access point, wherein the
determination is based on the first paging identifier and the
information relative to the reserved time interval.
14. The method of claim 13, wherein the determination comprises
determining whether the station is scheduled for transmission to
the access point.
15. The method of claim 13, wherein if the determination is to send
a polling message, the method further comprises transmitting a
message to the access point during the reserved time interval.
16. The method of claim 13, wherein if the determination is not to
send a polling message, the method further comprises waiting until
expiration of the reserved time interval.
17. The method of claim 16, wherein, upon expiration of the
reserved time interval, the method further comprises transmitting a
message to the access point.
18. The method of claim 13, wherein transmitting the message is
based on the result of a contention with one or more devices.
19. The method of claim 17, wherein transmitting the message is
based on the result of a contention with one or more devices.
20. The method of claim 13, wherein a contention comprises
assigning to a device a time slot to access the medium.
21. The method of claim 13, wherein a contention comprises
assigning to a device a value to be used for random back-off.
22. The method of claim 13, wherein a contention comprises
assigning to a device a deterministic back-off value.
23. The method of claim 6, wherein the schedule indicates an order,
wherein the order is randomized.
24. The method of claim 6, wherein the station is paged if the at
least one paging identifier is within a given range of paging
identifiers.
25. An access point configured for wireless communication,
comprising: a processor; memory in electronic communication with
the processor; instructions stored in the memory, the instructions
being executable to: determine a transmission schedule for a first
plurality of stations, wherein the first plurality of stations is
selected from a second plurality of stations; and determine a
duration of a reserved time interval that is reserved for
transmission.
26. The access point of claim 25, wherein the paging message is
associated with at least one paging identifier of a plurality of
paging identifiers, wherein each of the plurality of paging
identifiers is associated with at least one station of the first
plurality of stations.
27. The access point of claim 26, wherein the instructions are
further executable to transmit the paging message to at least one
of the second plurality of stations.
28. The access point of claim 25, wherein the instructions are
further executable to communicate the duration of the reserved time
interval to at least one of the second plurality of stations.
29. An access point configured for wireless communication,
comprising: a processor; memory in electronic communication with
the processor; instructions stored in the memory, the instructions
being executable to: determine a reserved time interval; and set
the reserved time interval for at least one paged station by
setting a network allocation vector.
30. A station configured for wireless communication, comprising: a
processor; memory in electronic communication with the processor;
instructions stored in the memory, the instructions being
executable to: determine a schedule for transmitting a polling
message to an access point, wherein the schedule is based on at
least one paging identifier.
31. The station of claim 30, wherein the schedule comprises a time
at which the station transmits the polling message.
32. The station of claim 30, wherein the schedule comprises a time
at which the station begins contention for a communication channel
to transmit the polling message.
33. The station of claim 30, wherein the schedule comprises a
counter, which the station counts down before transmission of a
transmit polling message while a communication channel is idle.
34. The station of claim 30, wherein the schedule is based on a
hash function of the station first paging identifier.
35. The station of claim 30, wherein the instructions are further
executable to obtain information relative to a time interval
reserved for transmission by a plurality of stations selected from
a set of stations.
36. The station of claim 35, wherein the instructions are further
executable to perform a determination as to whether to send a
polling message to the access point, wherein the determination is
based on the first paging identifier and the information relative
to the reserved time interval.
37. A station configured for wireless communication, comprising: a
processor; memory in electronic communication with the processor;
instructions stored in the memory, the instructions being
executable to: obtain information relative to a time interval
reserved for transmission by a plurality of stations selected from
a second plurality of stations; and perform a determination as to
whether to send a polling message to an access point, wherein the
determination is based on the first paging identifier and the
information relative to the reserved time interval.
38. The station of claim 37, wherein the determination comprises
determining whether the station is scheduled for transmission to
the access point.
39. The station of claim 37, wherein if the determination is to
send a polling message, the instructions are further executable to
transmit a message to the access point during the reserved time
interval.
40. The station of claim 37, wherein if the determination is not to
send a polling message, the instructions are further executable to
wait until expiration of the reserved time interval.
41. The station of claim 40, wherein, upon expiration of the
reserved time interval, the instructions are further executable to
transmit a message to the access point.
42. The station of claim 39, wherein transmitting the message is
based on the result of a contention with one or more devices.
43. The station of claim 40, wherein transmitting the message is
based on the result of a contention with one or more devices.
44. The station of claim 37, wherein a contention comprises
assigning to a device a time slot to access the medium.
45. The station of claim 37, wherein a contention comprises
assigning to a device a value to be used for random back-off.
46. The station of claim 37, wherein a contention comprises
assigning to a device a deterministic back-off value.
47. The station of claim 30, wherein the schedule indicates an
order, wherein the order is randomized.
48. The station of claim 30, wherein the station is paged if the at
least one paging identifier is within a given range of paging
identifiers.
49. An apparatus configured for wireless communication, comprising:
means for determining a transmission schedule for a first plurality
of stations, wherein the first plurality of stations is selected
from a second plurality of stations; and means for determining a
duration of a reserved time interval that is reserved for
transmission.
50. An apparatus configured for wireless communication, comprising:
means for determining a reserved time interval; and means for
setting the reserved time interval for at least one paged station
by setting a network allocation vector.
51. An apparatus configured for wireless communication, comprising:
means for determining a schedule for transmitting a polling message
to an access point, wherein the schedule is based on at least one
paging identifier.
52. An apparatus configured for wireless communication, comprising:
means for obtaining information relative to a time interval
reserved for transmission by a plurality of apparatuses selected
from a second plurality of apparatuses; and means for performing a
determination as to whether to send a polling message to an access
point, wherein the determination is based on the first paging
identifier and the information relative to the reserved time
interval.
53. A computer-program product for wireless communication, the
computer-program product comprising a non-transitory
computer-readable medium having instructions thereon, the
instructions comprising: code for causing an access point to
determine a transmission schedule for a first plurality of
stations, wherein the first plurality of stations is selected from
a second plurality of stations; and code for causing the access
point to determine a duration of a reserved time interval that is
reserved for transmission.
54. A computer-program product for wireless communication, the
computer-program product comprising a non-transitory
computer-readable medium having instructions thereon, the
instructions comprising: code for causing an access point to
determine a reserved time interval; and code for causing the access
point to set the reserved time interval for at least one paged
station by setting a network allocation vector.
55. A computer-program product for wireless communication, the
computer-program product comprising a non-transitory
computer-readable medium having instructions thereon, the
instructions comprising: code for causing a station to determine a
schedule for transmitting a polling message to an access point,
wherein the schedule is based on at least one paging
identifier.
56. A computer-program product for wireless communication, the
computer-program product comprising a non-transitory
computer-readable medium having instructions thereon, the
instructions comprising: code for causing a station to obtain
information relative to a time interval reserved for transmission
by a plurality of stations selected from a second plurality of
stations; and code for causing the station to perform a
determination as to whether to send a polling message to an access
point, wherein the determination is based on the first paging
identifier and the information relative to the reserved time
interval.
Description
RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 13/572,427 filed Aug. 10, 2012, which is related to and
claims priority from U.S. Provisional Patent Application Ser. No.
61/523,033 filed Aug. 12, 2011, for "SYSTEMS AND METHODS FOR LOW
OVERHEAD PAGING," U.S. Provisional Patent Application Ser. No.
61/552,444, filed Oct. 27, 2011, for "Systems and methods for low
overhead paging," U.S. Provisional Patent Application Ser. No.
61/552,661 filed Oct. 28, 2011, for "SYSTEMS AND METHODS FOR LOW
OVERHEAD PAGING," U.S. Provisional Patent Application Ser. No.
61/591,493, filed Jan. 27, 2012, for "SYSTEMS AND METHODS FOR LOW
OVERHEAD PAGING," and U.S. Provisional Patent Application Ser. No.
61/598,200, filed Feb. 13, 2012, for "SYSTEMS AND METHODS FOR LOW
OVERHEAD PAGING."
TECHNICAL FIELD
[0002] The present disclosure relates generally to electronic
devices. More specifically, the present disclosure relates to
devices for reduced overhead paging.
BACKGROUND
[0003] In the last several decades, the use of electronic devices
has become common. In particular, advances in electronic technology
have reduced the cost of increasingly complex and useful electronic
devices. Cost reduction and consumer demand have proliferated the
use of electronic devices such that they are practically ubiquitous
in modern society. As the use of electronic devices has expanded,
so has the demand for new and improved features of electronic
devices. More specifically, electronic devices that perform
functions faster, more efficiently or with higher quality are often
sought after.
[0004] Some electronic devices (e.g., cellular phones, smart
phones, computers, etc.) communicate with other electronic devices.
These electronic devices may be referred to as communication
devices. These electronic devices may generate and transmit data to
other electronic devices. For example, a laptop computer may format
data into packets and wirelessly transmit the packets to an access
point.
[0005] In many telecommunication systems, communications networks
are used to exchange messages among several interacting spatially
separated devices. Networks may be classified according to
geographic scope, which could be, for example, a metropolitan area,
a local area, or a personal area. Such networks would be designated
respectively as a wide area network (WAN), metropolitan area
network (MAN), local area network (LAN), wireless local area
network (WLAN), or personal area network (PAN). Networks also
differ according to the switching/routing technique used to
interconnect the various network nodes and devices (e.g. circuit
switching vs. packet switching), the type of physical media
employed for transmission (e.g. wired vs. wireless), and the set of
communication protocols used (e.g. Internet protocol suite, SONET
(Synchronous Optical Networking), Ethernet, etc.).
[0006] Wireless networks are often preferred when the network
elements are mobile and thus have dynamic connectivity needs, or if
the network architecture is formed in an ad hoc, rather than fixed,
topology. Wireless networks employ intangible physical media in an
unguided propagation mode using electromagnetic waves in the radio,
microwave, infra-red, optical, etc., frequency bands. Wireless
networks advantageously facilitate user mobility and rapid field
deployment when compared to fixed wired networks.
[0007] Some aspects of network control may require overhead
signaling. However, known approaches to network control may be
inefficient, often requiring excess amounts of bandwidth, time
and/or power to operate. As can be observed from this discussion,
systems and methods that improve network control efficiency may be
beneficial.
SUMMARY
[0008] A method for reduced overhead paging by an access point is
described. The method includes assigning at least one paging
identifier to at least one station. The method also includes
partitioning a paging identifier space into paging identifier sets.
The method further includes generating a paging message based on at
least one of the paging identifier sets and the at least one paging
identifier. The method additionally includes sending the paging
message.
[0009] At least one of the paging identifier sets may include a
continuous interval of multiple paging identifiers. The paging
message may include an explicit identifier that identifies at least
one of the paging identifier sets. At least one paging identifier
set may be implicitly identified by a sequence number associated
with the paging message.
[0010] At least one paging identifier set may be implicitly
identified by a time at which the paging message is sent. The at
least one paging identifier may be addressed relative to at least
one of the paging identifier sets. A relative position of the at
least one paging identifier may be assigned through a specific
management message. A relative position in the at least one paging
identifier set may represent an offset corresponding to the at
least one paging identifier.
[0011] Absolute addressing may be utilized to identify the at least
one paging identifier in at least one paging identifier set.
Absolute addressing may include a local address, a global address
or a paging identifier.
[0012] No explicit indication may be used to address the at least
one paging identifier in at least one paging identifier set. All
stations corresponding to the at least one paging identifier set
may be implicitly paged when the paging message indicates the at
least one paging identifier set. One bit may indicate whether all
stations corresponding to the at least one paging identifier set
are paged. All stations corresponding to a given range of paging
identifiers may be paged.
[0013] The access point may be an access point in accordance with
Institute of Electrical and Electronics Engineers (IEEE) 802.11
specifications.
[0014] The method may include compressing the paging message to
obtain a compressed paging message. Sending the paging message may
include transmitting the compressed paging message to the at least
one station.
[0015] The method may include scheduling a transmission by one or
more stations of the at least one station. The method may include
generating the at least one paging message based on the scheduling
of the one or more stations of the at least one station.
[0016] The paging message may include a bitmap element. The method
may include defining at least one sub-bitmap element. The method
may also include including a variable length bitmap into the at
least one sub-bitmap element.
[0017] The method may include compressing the bitmap to obtain
running length sequences based at least in part on the bitmap. The
method may include assigning a different association identifier.
The method may include assigning an association identifier to the
at least one station.
[0018] The paging message may include one or more of the group
consisting of an equipment identifier field, a length field, a
control field, an offset field and a bitmap. The paging message may
include an offset, a length and/or a bitmap.
[0019] A method for reduced overhead paging by a station is also
described. The method includes determining at least one paging
identifier assigned to the station. The method also includes
determining at least one paging identifier set corresponding to the
at least one paging identifier. The method further includes
determining whether a paging message corresponds to the station
based on the at least one paging identifier set. The method
additionally includes determining whether the station is paged if
the paging message corresponds to the station.
[0020] The method may include setting the station to an awake state
if the station is paged. Determining whether the paging message
corresponds to the station may be based on whether an explicit
identifier identifies the at least one paging identifier set
corresponding to the at least one paging identifier. Determining
whether the paging message corresponds to the station may be based
on whether the at least one paging identifier set is implicitly
identified by a sequence number associated with the paging message.
Determining whether the paging message corresponds to the station
may be based on whether the at least one paging identifier set is
implicitly identified by a time at which the paging message is
sent.
[0021] The station may be paged if the at least one paging
identifier is addressed relative to at the least one paging
identifier set. A relative position of the at least one paging
identifier may be assigned through a specific management message. A
relative position in the at least one paging identifier set may
represent an offset corresponding to the at least one paging
identifier. The station may be paged if absolute addressing
identifies the at least one paging identifier in the at least one
paging identifier set.
[0022] Absolute addressing may include a local address, a global
address or a paging identifier. No explicit indication may be used
to address the at least one paging identifier in at least one
paging identifier set. The station may be paged implicitly if the
at least one paging identifier set corresponds to the station. The
paging message may include one bit that indicates whether the
station corresponding to the at least one paging identifier set is
paged.
[0023] The station may be paged if the at least one paging
identifier is within a given range of paging identifiers. The
station may be a station in accordance with Institute of Electrical
and Electronics Engineers (IEEE) 802.11 specifications.
[0024] The method may include receiving at least one compressed
paging message from an access point. The method may also include
reconstructing the paging message from the compressed paging
message.
[0025] The paging message may be associated with the at least one
paging identifier of the at least one paging identifier set. Each
of the at least one paging identifier may be associated with at
least one station of a set of stations.
[0026] The method may include selecting a first paging identifier
from a plurality of paging identifiers that are included in the
paging message. The method may also include transmitting a request
to an access point indicating selection of the first paging
identifier.
[0027] A method for wireless communication by a station is also
described. The method includes preparing a polling message
comprising a token number. The token number corresponds to the
token number in one or more paging messages and is configured to
indicate a correspondence between the polling message and the one
or more paging messages. The method also includes transmitting the
polling message to an access point.
[0028] The paging message may include an equipment identifier
field, a length field, a control field, an offset field and/or a
bitmap. The station may have an association identifier. The paging
message may include offset, a length or a bitmap.
[0029] A method for wireless communication by an access point is
also described. The method includes determining a transmission
schedule for a first plurality of stations. The first plurality of
stations may be selected from a second plurality of stations. The
method also includes determining a duration of a reserved time
interval that is reserved for transmission.
[0030] The paging message may be associated with at least one
paging identifier of a plurality of paging identifiers. Each of the
plurality of paging identifiers may be associated with at least one
station of the first plurality of stations.
[0031] The method may include transmitting the paging message to at
least one of the second plurality of stations. The method may also
include communicating the duration of the reserved time interval to
at least one of the second plurality of stations.
[0032] Another method for wireless communication by an access point
is also described. The method includes determining a reserved time
interval. The method also includes setting the reserved time
interval for at least one paged station by setting a network
allocation vector.
[0033] Another method for wireless communication by an access point
is also described. The method includes preparing a plurality of
paging messages. Each of the plurality of paging messages is
associated with at least one paging identifier of a plurality of
paging identifiers and comprises a token number. Each of the
plurality of paging identifiers is associated with at least one
station of a set of stations. The method also includes transmitting
at least one paging message to the at least one station. The method
further includes receiving a polling message from the at least one
station. The polling message includes the token number. The token
number corresponds to the token number in one or more paging
messages and is configured to indicate a correspondence between the
polling message and the one or more paging messages. The method
additionally includes associating the one or more paging messages
with the polling message.
[0034] Another method for wireless communication by a station is
also described. The method includes determining a schedule for
transmitting a polling message to an access point. The schedule is
based on at least one paging identifier.
[0035] The schedule may include a time at which the station
transmits the polling message. The schedule may include a time at
which the station begins contention for a communication channel to
transmit the polling message. The schedule may include a counter,
which the station may count down before transmission of a transmit
polling message while a communication channel is idle. The schedule
may be based on a hash function of the station first paging
identifier.
[0036] The method may include obtaining information relative to a
time interval reserved for transmission by a plurality of stations
selected from a set of stations. The method may include performing
a determination as to whether to send a polling message to the
access point. The determination may be based on the first paging
identifier and the information relative to the reserved time
interval.
[0037] Another method for wireless communication by a station is
also described. The method includes selecting a first paging
identifier from a plurality of paging identifiers based on a
schedule by which an access point transmits paging messages
comprising the first paging identifier. The method also includes
transmitting a request to the access point indicating selection of
the first paging identifier.
[0038] The schedule may be predefined by the access point. The
schedule may be defined by the access point based on the receipt of
one or more requests. The request may include a frame comprising
the first paging identifier. The frame may further include an
equipment identifier, a length field, a control field, and timing
information regarding times when receipt of paging messages is
requested.
[0039] The method may include receiving a response to the request,
the response indicating assignment of the first paging identifier.
The response may include a frame comprising the first paging
identifier. The frame may also include an equipment identifier, a
length field, a control field, and timing information regarding
times paging messages associated with the first paging identifier
are transmitted by the transmitting device.
[0040] The method may include receiving at least one compressed
paging message from the access point. The method may include
reconstructing the paging message based at least in part on the
compressed paging message.
[0041] Another method for wireless communication by a station is
also described. The method includes obtaining information relative
to a time interval reserved for transmission by a plurality of
stations selected from a second plurality of stations. The method
also includes performing a determination as to whether to send a
polling message to an access point. The determination is based on
the first paging identifier and the information relative to the
reserved time interval.
[0042] The determination may include determining whether the
station is scheduled for transmission to the access point. If the
determination is to send a polling message, the method may further
include transmitting a message to the access point during the
reserved time interval. If the determination is not to send a
polling message, the method may further include waiting until
expiration of the reserved time interval. Upon expiration of the
reserved time interval, the method may further include transmitting
a message to the access point.
[0043] Transmitting the message may be based on the result of a
contention with one or more devices. Transmitting the message may
be based on the result of a contention with one or more
devices.
[0044] A contention may include assigning to a device a time slot
to access the medium. A contention may include assigning to a
device a value to be used for random back-off. A contention may
include assigning to a device a deterministic back-off value.
[0045] The schedule may indicate an order. The order may be
randomized. The station may be paged if the at least one paging
identifier is within a given range of paging identifiers.
[0046] An access point for reduced overhead paging is also
described. The access point includes a processor and instructions
stored in memory that is in electronic communication with the
processor. The access point assigns at least one paging identifier
to at least one station. The access point also partitions a paging
identifier space into paging identifier sets. The access point
further generates a paging message based on at least one of the
paging identifier sets and the at least one paging identifier. The
access point additionally sends the paging message.
[0047] A station for reduced overhead paging is also described. The
station includes a processor and instructions stored in memory that
is in electronic communication with the processor. The station
determines at least one paging identifier assigned to the station.
The station also determines at least one paging identifier set
corresponding to the at least one paging identifier. The station
further determines whether a paging message corresponds to the
station based on the at least one paging identifier set. The
station additionally determines whether the station is paged if the
paging message corresponds to the station.
[0048] A station configured for wireless communication is
described. The station includes a processor and instructions stored
in memory that is in electronic communication with the processor.
The station prepares a polling message including a token number.
The token number corresponds to the token number in one or more
paging messages and is configured to indicate a correspondence
between the polling message and the one or more paging messages.
The station transmits the polling message to an access point.
[0049] An access point configured for wireless communication is
described. The access point includes a processor and instructions
stored in memory that is in electronic communication with the
processor. The access point determines a transmission schedule for
a first plurality of stations. The first plurality of stations is
selected from a second plurality of stations. The access point also
determines a duration of a reserved time interval that is reserved
for transmission.
[0050] Another access point configured for wireless communication
is also described. The access point includes a processor and
instructions stored in memory that is in electronic communication
with the processor. The access point determines a reserved time
interval. The access point also sets the reserved time interval for
at least one paged station by setting a network allocation
vector.
[0051] Another access point configured for wireless communication
is also described. The access point includes a processor and
instructions stored in memory that is in electronic communication
with the processor. The access point prepares a plurality of paging
messages. Each of the plurality of paging messages is associated
with at least one paging identifier of a plurality of paging
identifiers and comprises a token number. Each of the plurality of
paging identifiers is associated with at least one station of a set
of stations. The access point also transmits at least one paging
message to the at least one station. The access point further
receives a polling message from the at least one station. The
polling message includes the token number. The token number
corresponds to the token number in one or more paging messages and
is configured to indicate a correspondence between the polling
message and the one or more paging messages. The access point
additionally associates the one or more paging messages with the
polling message.
[0052] Another station configured for wireless communication is
also described. The station includes a processor and instructions
stored in memory that is in electronic communication with the
processor. The station determines a schedule for transmitting a
polling message to an access point. The schedule is based on at
least one paging identifier.
[0053] Another station configured for wireless communication is
also described. The station includes a processor and instructions
stored in memory that is in electronic communication with the
processor. The station selects a first paging identifier from a
plurality of paging identifiers based on a schedule by which an
access point transmits paging messages comprising the first paging
identifier. The station also transmits a request to the access
point indicating selection of the first paging identifier.
[0054] Another station configured for wireless communication is
also described. The station includes a processor and instructions
stored in memory that is in electronic communication with the
processor. The station obtains information relative to a time
interval reserved for transmission by a plurality of stations
selected from a second plurality of stations. The station also
performs a determination as to whether to send a polling message to
an access point. The determination is based on the first paging
identifier and the information relative to the reserved time
interval.
[0055] An apparatus for reduced overhead paging is also described.
The apparatus includes means for assigning at least one paging
identifier to at least one station. The apparatus also includes
means for partitioning a paging identifier space into paging
identifier sets. The apparatus further includes means for
generating a paging message based on at least one of the paging
identifier sets and the at least one paging identifier. The
apparatus additionally includes means for sending the paging
message.
[0056] Another apparatus for reduced overhead paging is also
described. The apparatus includes means for determining at least
one paging identifier assigned to the apparatus. The apparatus also
includes means for determining at least one paging identifier set
corresponding to the at least one paging identifier. The apparatus
further includes means for determining whether a paging message
corresponds to the apparatus based on the at least one paging
identifier set. The apparatus additionally includes means for
determining whether the apparatus is paged if the paging message
corresponds to the apparatus.
[0057] An apparatus configured for wireless communication is also
described. The apparatus includes means for preparing a polling
message comprising a token number. The token number corresponds to
the token number in one or more paging messages and is configured
to indicate a correspondence between the polling message and the
one or more paging messages. The apparatus also includes means for
transmitting the polling message to an access point.
[0058] Another apparatus configured for wireless communication is
also described. The apparatus includes means for determining a
transmission schedule for a first plurality of stations. The first
plurality of stations is selected from a second plurality of
stations. The apparatus also includes means for determining a
duration of a reserved time interval that is reserved for
transmission.
[0059] Another apparatus configured for wireless communication is
also described. The apparatus includes means for determining a
reserved time interval. The apparatus also includes means for
setting the reserved time interval for at least one paged station
by setting a network allocation vector.
[0060] Another apparatus configured for wireless communication is
also described. The apparatus includes means for preparing a
plurality of paging messages. Each of the plurality of paging
messages is associated with at least one paging identifier of a
plurality of paging identifiers and comprises a token number. Each
of the plurality of paging identifiers is associated with at least
one station of a set of stations. The apparatus also includes means
for transmitting at least one paging message to the at least one
station. The apparatus further includes means for receiving a
polling message from the at least one station. The polling message
comprises the token number. The token number corresponds to the
token number in one or more paging messages and is configured to
indicate a correspondence between the polling message and the one
or more paging messages. The apparatus additionally includes means
for associating the one or more paging messages with the polling
message.
[0061] Another apparatus configured for wireless communication is
also described. The apparatus includes means for determining a
schedule for transmitting a polling message to an access point. The
schedule is based on at least one paging identifier.
[0062] Another apparatus configured for wireless communication is
also described. The apparatus includes means for selecting a first
paging identifier from a plurality of paging identifiers based on a
schedule by which an access point transmits paging messages
comprising the first paging identifier. The apparatus also includes
means for transmitting a request to the access point indicating
selection of the first paging identifier.
[0063] Another apparatus configured for wireless communication is
also described. The apparatus includes means for obtaining
information relative to a time interval reserved for transmission
by a plurality of apparatuses selected from a second plurality of
apparatuses. The apparatus also includes means for performing a
determination as to whether to send a polling message to an access
point. The determination is based on the first paging identifier
and the information relative to the reserved time interval.
[0064] A computer-program product for reduced overhead paging is
described. The computer-program product includes a non-transitory
computer-readable medium with instructions. The instructions
include code for causing an access point to assign at least one
paging identifier to at least one station. The instructions also
include code for causing the access point to partition a paging
identifier space into paging identifier sets. The instructions
further include code for causing the access point to generate a
paging message based on at least one of the paging identifier sets
and the at least one paging identifier. The instructions
additionally include code for causing the access point to send the
paging message.
[0065] Another computer-program product for reduced overhead paging
is also described. The computer-program product includes a
non-transitory computer-readable medium with instructions. The
instructions include code for causing a station to determine at
least one paging identifier assigned to a station. The instructions
also include code for causing the station to determine at least one
paging identifier set corresponding to the at least one paging
identifier. The instructions further include code for causing the
station to determine whether a paging message corresponds to the
station based on the at least one paging identifier set. The
instructions additionally include code for causing the station to
determine whether the station is paged if the paging message
corresponds to the station.
[0066] A computer-program product for wireless communication is
described. The computer-program product includes a non-transitory
computer-readable medium with instructions. The instructions
include code for causing a station to prepare a polling message
comprising a token number. The token number corresponds to the
token number in one or more paging messages and is configured to
indicate a correspondence between the polling message and the one
or more paging messages. The instructions also include code for
causing the station to transmit the polling message to an access
point.
[0067] Another computer-program product for wireless communication
is also described. The computer-program product includes a
non-transitory computer-readable medium with instructions. The
instructions include code for causing an access point to determine
a transmission schedule for a first plurality of stations. The
first plurality of stations is selected from a second plurality of
stations. The instructions also include code for causing the access
point to determine a duration of a reserved time interval that is
reserved for transmission.
[0068] Another computer-program product for wireless communication
is also described. The computer-program product includes a
non-transitory computer-readable medium with instructions. The
instructions include code for causing an access point to determine
a reserved time interval. The instructions also include code for
causing the access point to set the reserved time interval for at
least one paged station by setting a network allocation vector.
[0069] Another computer-program product for wireless communication
is also described. The computer-program product includes a
non-transitory computer-readable medium with instructions. The
instructions include code for causing an access point to prepare a
plurality of paging messages. Each of the plurality of paging
messages is associated with at least one paging identifier of a
plurality of paging identifiers and comprises a token number. Each
of the plurality of paging identifiers is associated with at least
one station of a set of stations. The instructions also include
code for causing the access point to transmit at least one paging
message to the at least one station. The instructions further
include code for causing the access point to receive a polling
message from the at least one station. The polling message includes
the token number. The token number corresponds to the token number
in one or more paging messages and is configured to indicate a
correspondence between the polling message and the one or more
paging messages. The instructions additionally include code for
causing the access point to associate the one or more paging
messages with the polling message.
[0070] Another computer-program product for wireless communication
is also described. The computer-program product includes a
non-transitory computer-readable medium with instructions. The
instructions include code for causing a station to determine a
schedule for transmitting a polling message to an access point. The
schedule is based on at least one paging identifier.
[0071] Another computer-program product for wireless communication
is also described. The computer-program product includes a
non-transitory computer-readable medium with instructions. The
instructions include code for causing a station to select a first
paging identifier from a plurality of paging identifiers based on a
schedule by which an access point transmits paging messages
comprising the first paging identifier. The instructions also
include code for causing the station to transmit a request to the
access point indicating selection of the first paging
identifier.
[0072] Another computer-program product for wireless communication
is also described. The computer-program product includes a
non-transitory computer-readable medium with instructions. The
instructions include code for causing a station to obtain
information relative to a time interval reserved for transmission
by a plurality of stations selected from a second plurality of
stations. The instructions also include code for causing the
station to perform a determination as to whether to send a polling
message to an access point. The determination is based on the first
paging identifier and the information relative to the reserved time
interval.
BRIEF DESCRIPTION OF THE DRAWINGS
[0073] FIG. 1 shows one example of an access point and one or more
stations in which systems and methods for reduced overhead paging
may be implemented;
[0074] FIG. 2 is a flow diagram illustrating one configuration of a
method for reduced overhead paging;
[0075] FIG. 3 is a flow diagram illustrating another configuration
of a method for reduced overhead paging;
[0076] FIG. 4 is a diagram illustrating examples of paging messages
over time;
[0077] FIG. 5 is a diagram illustrating examples of paging messages
in accordance with the systems and methods disclosed herein;
[0078] FIG. 6 is a block diagram illustrating one example of
station elements that may be implemented for reduced overhead
paging;
[0079] FIG. 7 illustrates one example of a frame format for a
message;
[0080] FIG. 8 illustrates another example of a frame format for a
message;
[0081] FIG. 9 illustrates another example of a frame format for a
message;
[0082] FIG. 10 illustrates another example of a paging message;
[0083] FIG. 11 illustrates another example of a paging message;
[0084] FIG. 12 is a diagram illustrating a more specific example of
a paging message;
[0085] FIG. 13 illustrates another more specific example of a
paging message;
[0086] FIG. 14 is a diagram illustrating one example of a paging
mechanism;
[0087] FIG. 15 is a flow diagram illustrating one configuration of
a method for determining an operational state;
[0088] FIG. 16 is a flow diagram illustrating one configuration of
a method for compressing a paging message;
[0089] FIG. 17 is a flow diagram illustrating another configuration
of a method for compressing a paging message;
[0090] FIG. 18 is a flow diagram illustrating another configuration
of a method for compressing a paging message;
[0091] FIG. 19 is a flow diagram illustrating one configuration of
a method for receiving a compressed paging message;
[0092] FIG. 20 is a flow diagram illustrating one configuration of
a method for paging receivers;
[0093] FIG. 21 is a flow diagram illustrating one configuration of
a method for contention among receivers;
[0094] FIG. 22 illustrates certain components that may be included
within a station; and
[0095] FIG. 23 illustrates certain components that may be included
within an access point.
DETAILED DESCRIPTION
[0096] The systems and methods disclosed herein may be applied to a
variety of electronic devices. Examples of electronic devices
include voice recorders, video cameras, audio players (e.g., Moving
Picture Experts Group-1 (MPEG-1) or MPEG-2 Audio Layer 3 (MP3)
players), video players, audio recorders, desktop computers, laptop
computers, personal digital assistants (PDAs), gaming systems, etc.
One kind of electronic device is a communication device, which may
communicate with another device. Examples of communication devices
include telephones, laptop computers, desktop computers, cellular
phones, smartphones, wireless or wired modems, e-readers, tablet
devices, gaming systems, cellular telephone base stations or nodes,
access points, wireless gateways and wireless routers, etc.
[0097] An electronic device or communication device may operate in
accordance with certain industry standards, such as International
Telecommunication Union (ITU) standards and/or Institute of
Electrical and Electronics Engineers (IEEE) standards (e.g.,
Wireless Fidelity or "Wi-Fi" standards such as 802.11a, 802.11b,
802.11g, 802.11n and/or 802.11ac). Other examples of standards that
a communication device may comply with include IEEE 802.16 (e.g.,
Worldwide Interoperability for Microwave Access or "WiMAX"), Third
Generation Partnership Project (3GPP), 3GPP Long Term Evolution
(LTE), Global System for Mobile Telecommunications (GSM) and others
(where a communication device may be referred to as a User
Equipment (UE), Node B, evolved Node B (eNB), mobile device, mobile
station, subscriber station, remote station, access point, station,
access terminal, mobile terminal, terminal, user terminal,
subscriber unit, etc., for example). While some of the systems and
methods disclosed herein may be described in terms of one or more
standards, this should not limit the scope of the disclosure, as
the systems and methods may be applicable to many systems and/or
standards.
[0098] It should be noted that some communication devices may
communicate wirelessly and/or may communicate using a wired
connection or link. For example, some communication devices may
communicate with other devices using an Ethernet protocol. The
systems and methods disclosed herein may be applied to
communication devices that communicate wirelessly and/or that
communicate using a wired connection or link. In some
configurations, the systems and methods disclosed herein may be
applied to a communication device that communicates with another
device using a satellite.
[0099] Devices in a wireless network may transmit/receive
information between each other. Further, devices that are not
actively transmitting/receiving information in the wireless network
may enter a doze state to conserve power, where the devices do not
actively transmit/receive information in the doze state. These
devices may further utilize paging messages to determine when to
wake up from a doze state and enter an awake state in order to
transmit/receive data. Thus, improved systems, methods, and devices
for transmitting and processing paging messages may be
beneficial.
[0100] Popular wireless network technologies may include various
types of wireless local area networks (WLANs). A WLAN may be used
to interconnect nearby devices together, employing widely used
networking protocols. The various aspects described herein may
apply to any communication standard, such as a wireless
protocol.
[0101] In some aspects, wireless signals in a sub-gigahertz band
may be transmitted according to the 802.11ah protocol using
orthogonal frequency-division multiplexing (OFDM), direct-sequence
spread spectrum (DSSS) communications, a combination of OFDM and
DSSS communications or other schemes. Implementations of the
802.11ah protocol may be used for sensors, metering and smart grid
networks. Advantageously, aspects of certain devices implementing
the 802.11ah protocol may consume less power than devices
implementing other wireless protocols, and/or may be used to
transmit wireless signals across a relatively long range, for
example about one kilometer or longer.
[0102] In some implementations, a WLAN includes various devices
which are the components that access the wireless network. For
example, there may be two types of devices: access points ("APs")
and clients (also referred to as stations or "STAs"). In general,
an AP may serve as a hub or base station for the WLAN and an STA
serves as a user of the WLAN. For example, an STA may be a laptop
computer, a personal digital assistant (PDA), a mobile phone, etc.
In an example, an STA connects to an AP via a WiFi (e.g., IEEE
802.11 protocol such as 802.11ah) compliant wireless link to obtain
general connectivity to the Internet or to other wide area
networks. In some implementations, an STA may also be used as an
AP.
[0103] An access point ("AP") may also comprise, be implemented as
or known as a NodeB, Radio Network Controller ("RNC"), eNodeB, Base
Station Controller ("BSC"), Base Transceiver Station ("BTS"), Base
Station ("BS"), Transceiver Function ("TF"), Radio Router, Radio
Transceiver or some other terminology.
[0104] A station "STA" may also comprise, be implemented as or
known as an access terminal ("AT"), a subscriber station, a
subscriber unit, a mobile station, a remote station, a remote
terminal, a user terminal, a user agent, a user device, user
equipment or some other terminology. In some implementations, an
access terminal may comprise a cellular telephone, a cordless
telephone, a Session Initiation Protocol ("SIP") phone, a wireless
local loop ("WLL") station, a personal digital assistant ("PDA"), a
handheld device having wireless connection capability or some other
suitable processing device connected to a wireless modem.
Accordingly, one or more aspects taught herein may be incorporated
into a phone (e.g., a cellular phone or smartphone), a computer
(e.g., a laptop), a portable communication device, a headset, a
portable computing device (e.g., a personal data assistant), an
entertainment device (e.g., a music or video device or a satellite
radio), a gaming device or system, a global positioning system
device or any other suitable device that is configured to
communicate via a wireless medium.
[0105] As described above, one or more of the devices described
herein may implement the 802.11ah standard, for example. Such
devices, whether used as an STA or AP or other device, may be used
for smart metering or in a smart grid network. Such devices may
provide sensor applications or be used in home automation. The
devices may instead or in addition be used in a healthcare context,
for example for personal healthcare. They may also be used for
surveillance, to enable extended-range Internet connectivity (e.g.
for use with hotspots) or to implement machine-to-machine
communications.
[0106] The systems and methods described herein enable low or
reduced overhead paging. In some implementations, the systems and
methods described herein may be applied to a wireless local area
network (WLAN).
[0107] IEEE 802.11 specifications define a `paging` message called
a traffic indication map (TIM). The traffic indication message is a
bitmap, where each bit corresponds to a station (STA). The traffic
indication map is sent in beacons or dedicated traffic indication
map frames. Each bit in the bitmap may correspond to a particular
station of a plurality of stations, and the value of each bit
(e.g., 0 or 1) may indicate the state the corresponding station
should be in (e.g., doze state or awake state). Accordingly, the
size of the bitmap may be directly proportional to the number of
stations in a wireless communications system. Therefore, a large
number of stations in the wireless communications system may result
in a large bitmap. Therefore, a paging message, and in some cases
the beacon or TIM frame including the paging message, may be
relatively large, requiring a large amount of bandwidth to
transmit. A traffic indication map may thus be relatively large,
especially if the number of stations to be supported will increase.
Further, each station may need to listen to the entire paging
message, and in some cases the beacon or TIM frame including the
paging message, in order to determine the state in which it should
operate. Accordingly, certain aspects described herein relate to
techniques for low overhead paging, whereby the stations
selectively decode or listen to only certain paging messages from
the access point.
[0108] The length of a traffic indication map also depends on how
the association identifiers (AIDs) are assigned. For example,
initial and final 0 bits are not sent. For instance, if an STA AID
1 and STA AID N have corresponding bits set to 1, then N bits are
sent. The order of assigning association identifiers matters.
[0109] The systems and methods disclosed herein provide approaches
for limiting overhead related to paging. In some implementations,
the systems and method disclosed herein may modify a known paging
concept by compressing the traffic indication map bitmap
representation. Additionally or alternatively, the systems and
methods disclosed herein may apply a hierarchical paging mechanism,
where each station only listens to selected pages. The systems and
methods disclosed herein may enable use of smaller frames and
enhanced power savings at stations.
[0110] The systems and methods disclosed herein may provide one or
more of the following approaches. An access point (AP) may assign
one or more paging identifiers to one or more stations. A paging
identifier may also be referred to as a "power save identifier" (PS
ID). The access point may partition a paging identifier space into
one or more paging identifier sets. A paging identifier set may
also be referred to as a "power save identifier set" (PS ID set).
As used herein, the "paging identifier space" may include all
paging identifiers available to an access point. Each paging
identifier set may be a subset of the paging identifier space
(e.g., a paging identifier set may be smaller than or include fewer
paging identifiers than the paging identifier space). However, a
special paging identifier set may include all paging identifiers.
The systems and methods disclosed herein may provide approaches to
index each paging identifier set and specify which station of the
paging identifier set is paged. In some configurations, an access
point may send only relevant paging information in a frame. For
example, times when paging may be sent may be defined for each
station.
[0111] Regarding paging identifier assignment, each station may be
assigned one or more paging identifiers. Additionally or
alternatively, one paging identifier may be assigned to one or more
stations. It should be noted that a paging identifier may be the
association identifier (AID) in some configurations. For example,
an association identifier may be a number (e.g., 16-bit number)
that exclusively identifies one station. In other configurations,
the association identifier(s) and paging identifier(s) may be
distinct pieces of information that are managed separately (by an
access point, for example) in some configurations.
[0112] Regarding partitioning, paging identifier sets may be
disjoint or overlapping. For example, a single paging identifier
may belong to one or more paging identifier sets. Additionally or
alternatively, paging identifier sets may be of different sizes or
of the same size. In some configurations, a paging identifier set
may include a continuous interval of paging identifiers. This may
provide a structure that is similar to that of a traffic indication
map. As described above, special paging identifier sets may include
all paging identifiers. For example, a special paging identifier
set may indicate broadcast, similar to a delivery traffic
indication map (DTIM).
[0113] One or more approaches may be implemented to indicate which
paging identifier set is being paged in accordance with the systems
and methods disclosed herein. In one configuration, each paging
identifier set may be identified by an explicit identifier sent in
a paging frame. For example, a 2 Byte field may provide indexing
for 2.sup.16 paging identifier sets. Additionally or alternatively,
a specific indication may be sent in the physical layer (PHY)
preamble.
[0114] In another configuration, each paging identifier set may be
implicitly identified by a sequence number associated with a sent
paging frame. For example, a SET ID=mod(Sequence Number, 256),
where "SET ID" is a paging identifier set number, "mod( )" is the
modulo operator and "Sequence Number" is the paging frame sequence
number.
[0115] In another configuration, each paging identifier set may be
implicitly identified by the time at which the frame is sent, for
example, a set of stations for which their associated paging
identifier satisfies a given condition with respect to the time at
which the frame is sent. Alternatively, one or more stations may
agree with an access point on a paging schedule.
[0116] One or more approaches may be implemented for addressing
individual stations within a paging identifier set. In one
configuration, individual stations may be addressed relative to the
paging identifier set. For example, a bitmap of N bits may be
utilized, where each bit indexes a specific station address
relative to the set. The relative position within the set may be
assigned a priori through a specific management message. This
management message may define the association between each paging
identifier and a paging identifier set. Alternatively, the relative
position within the paging identifier set may be represented by an
offset from a paging identifier set value (assuming the paging
identifier set value represents a starting address for the paging
identifier set). For example, the bit in position N in the bitmap
refers to the station with a paging
identifier=N+256*PID_Set_Number, where "PID_Set_Number" denotes a
paging identifier set number or value. One benefit of this approach
is that it provides simple operation at the receiver (e.g.,
station). For instance, a receiver (e.g., station) may only need to
compare a station index (STA Index) or paging identifier value with
N+256*PID_Set_Number.
[0117] In another configuration, absolute addressing may be
utilized to identify individual stations within a paging identifier
set. For example, local or global addresses may identify individual
stations. In some implementations, partial addresses may be used.
Additionally or alternatively, full paging identifiers may be
utilized.
[0118] In yet another configuration, no explicit indication may be
used to address individual stations within a paging identifier set.
For example, whenever a paging identifier set is indexed, all
stations corresponding to the paging identifier set are implicitly
paged. Alternatively, for example, one bit may be utilized to
indicate whether all of or none of the stations corresponding to
the paging identifier set are paged. Alternatively, all stations
within a given range (e.g., 256*[PID_Set_Number: PID_Set_Number+1],
where PID_Set_Number is a paging identifier set number or value)
are paged.
[0119] At each paging epoch, a frame may be sent by an access
point. Each frame may page one or more sets of stations. Each frame
may include a list of specific stations being paged within the set.
In some configurations, the schedule at which each set is paged may
be defined a priori (e.g., the access point and stations may have a
defined schedule). A station may wake up at a time specified by the
schedule.
[0120] Various configurations are now described with reference to
the Figures, where like element names may indicate functionally
similar elements. The systems and methods as generally described
and illustrated in the Figures herein could be arranged and
designed in a wide variety of different configurations. Thus, the
following more detailed description of several configurations, as
represented in the Figures, is not intended to limit scope, as
claimed, but is merely representative of the systems and
methods.
[0121] FIG. 1 shows one example of an access point 104 and one or
more stations 106 in which systems and methods for reduced overhead
paging may be implemented. The access point 104 and the one or more
stations 106 may be included in a communication system 100. In some
configurations, the communication system 100 may operate pursuant
to a wireless standard (e.g., IEEE 802.11ah). The access point 104
may communicate with the one or more stations 106 and vice versa.
For example, the access point 104 and the one or more stations 106
may transmit and receive wireless communication signals.
[0122] A variety of procedures may be used for transmissions in the
communication system 100 between the access point 104 and the
stations 106. For example, signals may be sent and received between
the access point 104 and the stations 106 in accordance with
orthogonal frequency-division multiplexing/orthogonal
frequency-division multiple access (OFDM/OFDMA) techniques. In this
case, the communication system 100 may be referred to as an
OFDM/OFDMA system. Alternatively, signals may be sent and received
between the access point 104 and the stations 106 in accordance
with code division multiple access (CDMA) techniques. In this, the
communication system 100 may be referred to as a CDMA system.
[0123] A communication link that facilitates transmission from the
access point 104 to one or more of the stations 106 may be referred
to as a downlink (DL) 108, and a communication link that
facilitates transmission from one or more of the stations 106 to
the access point 104 may be referred to as an uplink (UL) 110.
Alternatively, a downlink 108 may be referred to as a forward link
or a forward channel and an uplink 110 may be referred to as a
reverse link or a reverse channel.
[0124] The access point 104 may act as a base station and provide
wireless communication coverage in a basic service area (BSA) 102.
The access point 104 and the stations 106 associated with the
access point 104 (that use the access point 104 for communication)
may be referred to as a basic service set (BSS). It should be noted
that the communication system 100 may not have a central access
point 104, but rather may function as a peer-to-peer network
between the stations 106. Accordingly, the functions of the access
point 104 described herein may alternatively be performed by one or
more of the stations 106. In other words, an access point may be a
station in some configurations.
[0125] The access point 104 may transmit a beacon signal (or simply
a "beacon"), via a communication link such as the downlink 108, to
the stations 106 of the system 100, which may help the stations 106
to synchronize their timing with the access point 104, or which may
provide other information or functionality. Such beacons may be
transmitted periodically. In one aspect, the period between
successive transmissions may be referred to as a superframe.
Transmission of a beacon may be divided into a number of groups or
intervals. In one aspect, the beacon may include, but is not
limited to, such information as timestamp information to set a
common clock, a peer-to-peer network identifier, a device
identifier, capability information, a superframe duration,
transmission direction information, reception direction
information, a neighbor list, and/or an extended neighbor list,
some of which are described in additional detail below. Thus, a
beacon may include information that is common (e.g. shared) among
several devices and/or information specific to a given device.
[0126] In some aspects, a station 106 may be required to associate
with the access point 104 in order to send communications to and/or
receive communications from the access point 104. In one aspect,
information for associating is included in a beacon broadcast by
the access point 104. To receive such a beacon, the station 106
may, for example, perform a broad coverage search over a coverage
region. A search may also be performed by the station 106 by
sweeping a coverage region in a lighthouse fashion, for example.
After receiving the information for associating, the station 106
may transmit a reference signal, such as an association probe or
request, to the access point 104. In some aspects, the access point
104 may use backhaul services, for example, to communicate with a
larger network, such as the Internet or a public switched telephone
network (PSTN).
[0127] The access point 104 may include an access point paging
block/module 112, an access point transmit chain 118 and an access
point receive chain 120. As used herein, the term "block/module"
may be used to indicate that an element may be implemented in
hardware (e.g., circuitry), software or a combination of both. For
example, the access point paging block/module 112 may be
implemented in hardware, software or a combination of both.
[0128] The access point transmit chain 118 may include one or more
blocks/modules for formatting and transmitting information to the
station(s) 106. For example, the access point transmit chain 118
may include and/or be coupled to one or more encoders, modulators
(e.g., constellation mapper), amplifiers and/or antennas.
Additionally or alternatively, the access point transmit chain 118
may perform one or more functions such as scrambling, interleaving,
precoding, etc. The access point transmit chain 118 may transmit
information and/or data such as overhead data (e.g., paging
messages, beacons, control information, etc.) and payload data
(e.g., text, audio, voice, image, video, etc.).
[0129] In some configurations, the access point transmit chain 118
may be configured to wirelessly transmit messages, which may be
referred to as "paging messages" that are configured to indicate to
wireless devices whether or not the wireless devices need to wake
up from a doze state and enter an awake state as described herein.
For example, the access point transmit chain 118 may be configured
to transmit paging messages generated by the access point 104.
[0130] The access point receive chain 120 may include one or more
blocks/modules for receiving and deformatting information received
from the station(s) 106. For example, the access point receive
chain 120 may include and/or be coupled to one or more decoders,
demodulators, amplifiers and/or antennas. Additionally or
alternatively, the access point receive chain 120 may perform one
or more functions such as descrambling, deinterleaving, etc. The
access point receive chain 120 may receive information and/or data
such as overhead data (e.g., polling messages, control information,
etc.) and payload data (e.g., text, audio, voice, image, video,
etc.).
[0131] The access point paging block/module 112 may page the one or
more stations 106. For example, if a station 106 is in a power save
mode (e.g., sleep state) and the access point 104 has data for
transmission to that station 106, the paging block/module 112 may
generate a paging message directing the station 106 to enter an
awake state. As described above, known approaches for paging may
require relatively large amounts of overhead.
[0132] In accordance with the systems and methods herein, one or
more paging identifiers 116 may identify or correspond to one or
more stations 106. Paging identifiers 116 may be utilized in paging
procedures as described herein. A paging identifier 116 may
identify one or more stations 106. Additionally or alternatively,
multiple paging identifiers 116 may identify or correspond to the
same station 106. Examples of a paging identifier 116 include a
number, a string of bits, a code, an alphanumeric string, etc.
[0133] The access point paging block/module 112 may assign at least
one paging identifier 116 to at least one station 106. For example,
the access point paging block/module 112 may associate at least one
paging identifier A 116a with a particular station 106.
[0134] The access point paging block/module 112 may partition a
paging identifier space into paging identifier sets 114 (e.g.,
paging identifier sets A 114a). A "paging identifier space" may be
a set of all allowed paging identifiers 116. For example, a certain
number of bits may be allocated for paging identifiers 116.
Accordingly, the paging identifier space may include all possible
bit combinations or values for that number of bits. Partitioning
the paging identifier space may include grouping paging identifiers
116 (e.g., deriving subsets of the paging identifier space).
Accordingly, the access point paging block/module 112 may obtain
paging identifier sets A 114a, where each paging identifier set A
114a includes one or more paging identifiers A 116a.
[0135] The station 106 may include a station paging block/module
126, a station transmit chain 124 and a station receive chain 122.
The station paging block/module 126 may be implemented in hardware,
software or a combination of both.
[0136] The station transmit chain 124 may include one or more
blocks/modules for formatting and transmitting information to the
access point 104. For example, the station transmit chain 124 may
include and/or be coupled to one or more encoders, modulators
(e.g., constellation mapper), amplifiers and/or antennas.
Additionally or alternatively, the station transmit chain 124 may
perform one or more functions such as scrambling, interleaving,
precoding, etc. The station transmit chain 124 may transmit
information and/or data such as overhead data (e.g., polling
messages, control information, etc.) and payload data (e.g., text,
audio, voice, image, video, etc.).
[0137] The station receive chain 122 may include one or more
blocks/modules for receiving and deformatting information received
from the access point 104. For example, the station receive chain
122 may include and/or be coupled to one or more decoders,
demodulators, amplifiers and/or antennas. Additionally or
alternatively, the station receive chain 122 may perform one or
more functions such as descrambling, deinterleaving, etc. The
station receive chain 122 may receive information and/or data such
as overhead data (e.g., paging messages, polling messages, control
information, etc.) and payload data (e.g., text, audio, voice,
image, video, etc.). In some configurations, station receive chain
122 may be configured to wirelessly receive paging messages.
[0138] The station paging block/module 126 may control a station's
106 response (if any) to a paging message from the access point.
For example, the station paging block/module 126 may listen for a
paging message and/or interpret the paging message. In some
configurations, the station paging block/module 126 may only listen
for paging messages at particular times. If a station 106 is in a
power save mode (e.g., sleep state) and receives a paging message
directing the station 106 to enter an awake state, the station
paging block/module 126 may set the station 106 into an awake state
in order to receive a data transmission from the access point
104.
[0139] The station paging block/module 126 may determine at least
one paging identifier B 116b assigned to the station 106. For
example, the station 106 may receive a message from the access
point 104 that indicates a paging identifier assignment. The
station paging block/module 126 may designate the paging
identifier(s) B 116b as assigned paging identifier(s).
[0140] The station paging block/module 126 may determine at least
one paging identifier set B 114b corresponding to the at least one
paging identifier B 116b. For example, the station 106 may receive
a message that indicates a correspondence or an association between
the at least one paging identifier B 116b and a paging identifier
set B 114b. For instance, the message may indicate which paging
identifier B 116b is included within which paging identifier set B
114b.
[0141] Further detail regarding the functionality of the access
point 104 and the station(s) 106 is given above and/or below. In
other words, the access point 104 and/or the station(s) 106 may
function in accordance with the description (e.g., one or more of
the procedures, methods, approaches, structures, etc.) given above
and/or below.
[0142] More detail regarding an example of an implementation of the
systems and methods is given as follows. The access point 104
and/or a station 106 may be used to transmit and/or receive
communications including paging messages. That is, either an access
point 104 or a station 106 may serve as a transmitter or a receiver
device of paging messages. Certain implementations contemplate a
signal detector being used by software running on memory and a
processor to detect the presence of a transmitter or receiver.
[0143] The station 106 may have a plurality of operational modes.
For example, the station 106 may have a first operational mode
referred to as an awake state or active mode. In the awake state,
the station 106 may actively transmit and/or receive data with the
access point 104. Further, the station 106 may have a second
operational mode referred to as a power save mode. In the power
save mode, the station 106 may be in the "awake" state or in a
"doze" or "sleep" state (where the station 106 does not actively
transmit/receive data with the access point 104, for instance). For
example, the station receive chain 122 (and possibly a DSP and
signal detector of the station 106, for instance) may operate using
reduced power consumption in the doze state. Further, in the power
save mode, the station 106 may occasionally enter the awake state
to listen to messages from the access point 104 (e.g., paging
messages) that indicate to the station 106 whether or not the
station 106 needs to "wake up" (e.g., enter the awake state) at a
certain time so as to be able to transmit/receive data with the
access point 104.
[0144] Accordingly, in certain wireless communication systems 100,
the access point 104 may transmit paging messages to a plurality of
stations 106 in a power save mode in the same network as the access
point 104, indicating whether or not the stations 106 need to be in
an awake state or a doze state. For example, if a station 106
determines it is not being paged, it may remain in a doze state.
Alternatively, if the station 106 determines it may be paged, the
station 106 may enter an awake state for a certain period of time
to receive the page and further determine when to be in an awake
state based on the page. Further, the station 106 may stay in the
awake state for a certain period of time after receiving the page.
In another example, the station 106 may be configured to function
in other ways when being paged or not being paged that are
consistent with this disclosure. For example, the page may indicate
that the station 106 should enter an awake state for a certain
period of time because the access point 104 has data to transmit to
the station 106. In some configurations, the station 106 may poll
the access point 104 for data by sending the access point 104 a
polling message when in the awake state for the period of time. In
response to the polling message, the access point 104 may transmit
the data to the station 106. As another example, a station 106 may
enter a doze state after an access point concludes transmission of
a paging message or once the station 106 determines that the
station has not been paged by the paging message. The station 106
may then awake when the station 106 may start contending for the
medium or transmit any message as described in this disclosure.
[0145] As described above, each station 106 of the plurality of
stations 106 in the wireless communication system 100 may be
assigned at least one paging identifier 116 (by an access point
104, for example). Each station 106 may be assigned one or more
such paging identifiers 116. Further, a single paging identifier
116 may be assigned to one or more stations 106. Accordingly, one
or more stations 106 may be addressed by a given paging identifier
116. Further, a given station 106 may be addressed by one or more
paging identifiers 116. In some aspects, the paging identifiers may
be assigned to stations 106 during initialization of each station
106 (e.g., at the time of manufacture of the station 106, at the
first run time of the station 106, when a station 106 joins a new
wireless network such as wireless communication system 100, etc.).
In some aspects, the paging identifiers 116 may be assigned and/or
additionally revised (e.g., reassigned), such as through
communication with other devices in the wireless communication
system 100, such as the access point 104. In some aspects, the
access point 104 may determine or assign paging identifiers 116 for
the stations 106 associated with the access point 104 and transmit
messages indicative of the paging identifiers to the stations
106.
[0146] All of the paging identifiers 116 available (or
alternatively assigned to the stations 106) in the wireless
communication system 100 may be referred to as a paging identifier
space for the wireless communication system 100 (or alternatively
for the access point 104). This paging identifier space may be
divided into a plurality of paging identifier sets 114, each set
including one or more of the paging identifiers 116 in a paging
identifier set 114. As described above, these paging identifier
sets 114 may be disjoint or overlapping, meaning that in certain
aspects a plurality of the paging identifier sets 114 may include
the same paging identifier 116, and in certain aspects one paging
identifier set 114 may include a paging identifier 116 that another
paging identifier set 114 does not include. Further, the paging
identifier sets 114 may be of the same or different sizes, meaning
they contain the same or different numbers of paging identifiers.
Further, some paging identifier sets 114 may include a continuous
interval of paging identifiers (such as a sequential series of
paging identifiers 116), while some paging identifier sets 114 may
include paging identifiers 116 that do not form a continuous
interval. In one aspect, a special paging identifier set may
include the entire set of paging identifiers 116. Such a special
paging identifier set may be referred to as a broadcast paging
identifier subset. In certain aspects, similar to how the station
106 may be assigned a paging identifier so that the station 106 is
aware of its paging identifier as described above, the station 106
may be assigned or given information to identify the paging
identifier sets 114 that the station 106 is associated with. In
some configurations, the access point 104 may utilize the paging
identifier 116 and paging identifier sets 114 along with paging
messages as described herein to enable the stations 106 to
selectively receive only certain paging messages from the access
point 104.
[0147] In some configurations, a station 106 may have an
association identifier (AID). In some configurations, the one or
more paging identifiers are one or more AIDs. In other
configurations, AID may be distinct from the one or more paging
identifiers 116 of the station 106. The AID may identify the
station 106 within an area such as a BSA 102 (and/or within the
BSS, for example). The AID may be used as an address or a part of
an address and may be shorter than other addresses of the station
such as an Internet protocol (IP) address or a Media Access Control
(MAC) address. The AID may be included in a frame to uniquely
identify a sender or receiver of a message. For example, the AID
may be included in a MAC header to identify a transmitting station
when the AID may be used for addressing a frame. Further, a
presentation protocol data unit (PPDU) header may include an AID or
a partial AID that may be used as an early indication of an
intended receiver of the frame.
[0148] Advantageously, such a PPDU header may permit early
termination of processing a received PPDU that is indicated to be
for different receiver. In some aspects, the AID may be assigned
(by the access point 104, for example) at initialization of each
station 106 (e.g., at manufacture and/or when a station 106 joins a
wireless network).
[0149] A station 106 may have both an AID and one or more paging
identifiers 116 as described herein. For instance, one paging
identifier 116 may relate to a power save wake-up schedule or a
schedule at which an associated paging message is transmitted by an
access point. Further, if the power save wake-up schedule of the
station changes, a different paging identifier 116 and/or AID may
be assigned to the station 106.
[0150] In some configurations, paging messages may include a token
number. The token number may serve as an identifier of a paging
message. A station 106 paged by a paging message with a token
number may respond with a power save poll request message (PS-POLL)
that also includes the token number (taken from a beacon, for
example). The token number may include one or more of BSS
identifier (BSSID), TSF, etc. The token number accordingly may
enable an access point 104 to identify the PS-POLL as corresponding
to the paging message. Advantageously, the token number may be used
as an identifier for the paging message sender and permit the
PS-POLL sender to transmit less data in the PS-POLL since the
address of the sender or receiver may not be transmitted, for
example.
[0151] The token number included in paging messages may vary from
one paging message to subsequent paging messages. The token number
may change, for instance, based on a number of stations in the BSS
(and/or the BSA 102, for example), a formula, or a random
generation procedure. Advantageously, changing the token number
more frequently may prevent issues with overlapping BSSs where each
BSS utilizes token numbers or similar approaches.
[0152] FIG. 2 is a flow diagram illustrating one configuration of a
method 200 for reduced overhead paging. An access point 104 may
assign 202 at least one paging identifier 116 to at least one
station 106. For example, the access point 104 may associate at
least one paging identifier 116 with a particular station 106. In
some configurations, the access point 104 may send a message to the
station 106 indicating the assigned paging identifier 116.
[0153] The access point 104 may partition 204 a paging identifier
space into paging identifier sets 114. Partitioning the paging
identifier space may include grouping paging identifiers 116 (e.g.,
deriving subsets of the paging identifier space). Accordingly, the
access point paging block/module 112 may obtain paging identifier
sets A 114a, where each paging identifier set A 114a includes one
or more paging identifiers A 116a.
[0154] It should be noted that the paging identifier sets 114 may
be disjoint or overlapping. For example, a single paging identifier
116 may belong to one or more paging identifier sets 114.
Additionally or alternatively, paging identifier sets 114 may be of
different sizes or of the same size. In some configurations, a
paging identifier set 114 may include a continuous interval of
paging identifiers 116. This may provide a structure that is
similar to that of a traffic indication map. As described above,
special paging identifier sets may include all paging
identifiers.
[0155] In some configurations, the access point 104 may send a
message to the station indicating the paging identifier sets 114
(e.g., the paging identifier set(s) 114 that include one or more
paging identifiers 116 corresponding to the station 106). For
example, the message may indicate a relationship or association
between one or more paging identifier sets 114 and the one or more
paging identifiers 116 corresponding to the station 106. Each
paging identifier set 114 may be represented by and/or indicated by
a paging identifier set value. Examples of a paging identifier set
value include a number, a string of bits, a code and/or an
alphanumeric string, etc.
[0156] The access point 104 may generate 206 a paging message based
on the paging identifier sets 114 and the at least one paging
identifier 116. For example, each paging message may correspond to
(e.g., indicate) one or more paging identifier sets 114. In one
configuration, a paging identifier set 114 may be explicitly
identified in the paging message. For example, the paging message
may include a field (e.g., a two-byte field) that explicitly
indicates a paging identifier set 114. Additionally or
alternatively, an explicit identifier may be sent in a physical
layer preamble. In another configuration, the paging message may
implicitly indicate a paging identifier set 114 based on a sequence
number of a paging frame. In yet another configuration, the paging
message may implicitly indicate a paging identifier set 114 based
on the time at which the paging message is sent.
[0157] In generating 206 the paging message, the access point 104
may determine whether it has any data pending for transmission to a
station 106 and whether the station 106 is in a sleep state. If
there is data pending for transmission to the station 106 and the
station 106 is in a sleep state, the access point may generate 206
a paging message directing the station 106 to enter an awake state.
For example, the access point 104 may indicate that a station 106
is being paged if the individual station 106 is addressed or
indicated in the paging message with a corresponding paging
identifier set 114.
[0158] In one configuration, individual stations 106 may be
addressed relative to the paging identifier set 114 indicated by
the paging message. For example, a bitmap of N bits may be
utilized, where each bit indexes a specific station address
relative to the set. The relative position within the set may be
assigned a priori through a specific management message (in
assigning 202 the at least one paging identifier 116, for example).
This management message may define the association between each
paging identifier 116 and a paging identifier set 114.
Alternatively, the relative position within the paging identifier
set 114 may be represented by an offset from a paging identifier
set value (assuming the paging identifier set value represents a
starting address for the paging identifier set 114, for
instance).
[0159] In another configuration, absolute addressing may be
utilized to identify individual stations 106 within a paging
identifier set 114. For example, local or global addresses may
identify individual stations 106. In some implementations, partial
addresses may be used. Additionally or alternatively, full paging
identifiers may be utilized.
[0160] In yet another configuration, no explicit indication may be
used to address individual stations 106 within a paging identifier
set 114. For example, whenever a paging identifier set 114 is
indexed, all stations corresponding to the paging identifier set
114 are implicitly paged. Alternatively, for example, one bit may
be utilized to indicate whether all of or none of the stations 106
corresponding to the paging identifier set 114 are paged.
Alternatively, all stations 106 within a given range are paged.
[0161] The access point 104 may send 208 the paging message. For
example, at each paging epoch, a frame may be sent by the access
point 104. Each frame may page one or more sets of stations. Each
frame may include a list of specific stations being paged within
the set. In some configurations, the schedule at which each set is
paged may be defined a priori (e.g., the access point 104 and
stations 106 may have a defined schedule). A station 106 may wake
up at a time specified by the schedule.
[0162] FIG. 3 is a flow diagram illustrating another configuration
of a method 300 for reduced overhead paging. A station 106 may
determine 302 at least one paging identifier 116 assigned to the
station 106. For example, the station 106 may receive a message
from an access point 104 that indicates one or more paging
identifiers 116 that are assigned to the station 106.
[0163] The station 106 may determine 304 at least one paging
identifier set 114 corresponding to the at least one paging
identifier 116. For example, the station 106 may receive a message
from the access point 104 that indicates a relationship or
association between the at least one paging identifier 116
(assigned to the station 106) and the at least one paging
identifier set 114.
[0164] The station 106 may determine 306 whether a paging message
corresponds to the station 106 based on the at least one paging
identifier set 114. For example, this determination 306 may be
based on whether the paging message is associated with a paging
identifier set 114 that corresponds to the station 106. A paging
identifier set 114 may correspond to the station 106 if it includes
a paging identifier 116 that corresponds to or identifies the
station.
[0165] In making this determination 306, the station 106 may or may
not receive a paging message from the access point 104. In some
configurations, for example, the station 106 may only receive
paging messages according to a predetermined schedule that is based
on or associated with a paging identifier set 114 corresponding to
the station 106. For instance, the station 106 may disregard,
ignore and/or not receive paging messages that are sent at
unscheduled times. In other configurations, the station 106 may
receive all of the paging messages and disregard or ignore those
paging messages that do not correspond to a paging identifier set
114 corresponding to the station 106. Accordingly, if the station
106 determines 306 that a paging message does not correspond to the
station 106 based on the at least one paging identifier set 114
(because the paging message is not at a scheduled time for a paging
identifier set 114 corresponding to the station 106 and/or because
the paging message does not indicate a paging identifier set 114
corresponding to the station 106, for example), then the station
106 may determine 306 if a next paging message corresponds to the
station 106 based on the at least one paging identifier set
114.
[0166] If the paging message corresponds to the station 106 based
on the at least one paging identifier set 114 (e.g., the paging
message is at a scheduled time for a paging identifier set 114
corresponding to the station 106 and/or the paging message
indicates a paging identifier set 114 corresponding to the station
106), then the station 106 may determine 308 whether the station
106 is paged. For example, the station 106 may determine whether
the station 106 is addressed by the paging message. As described
above, the station 106 may be addressed relative to the paging
identifier set 114. For example, a particular position relative to
the paging identifier set 114 may address the station 106. In
another example, an offset from a paging identifier set value may
address the station 106. In yet another example, absolute
addressing (with full and/or partial addresses, for example) may be
utilized to address the station 106.
[0167] In other configurations, no explicit indication may be used
for individual stations 106 within a paging identifier set 114. For
example, all stations 106 corresponding to the paging identifier
set 114 may be implicitly paged when the paging identifier set 114
is indicated. Alternatively, an indicator (e.g., one bit) may
indicate whether all or none of the stations 106 corresponding to
the paging identifier set 114 are paged. In another alternative,
all stations 106 within a given range are paged.
[0168] If the station 106 is not paged, the station 106 may
determine 306 whether a next paging message corresponds to the
station based on the at least one paging identifier set 114.
However, if the station 106 is paged, then the station 106 may set
310 the station 106 to an awake state. While in the awake state,
for example, the station 106 may receive data from the access point
104.
[0169] FIG. 4 is a diagram illustrating examples of paging messages
428 over time 430. For instance, the paging messages 428a-c may be
transmitted by the access point 104 to stations 106 in the wireless
communication system 100 described in connection with FIG. 1. As
illustrated in FIG. 4, the access point 104 is configured to
transmit a plurality of paging messages 428 over time 430. The
paging messages 428 may be sent in a TIM frame, a beacon or using
some other appropriate signaling. In some implementations, the
stations 106 may be configured to listen to one or more of the
paging messages 428 as follows.
[0170] In some configurations, each paging message 428 may include
one or more paging identifier set values that correspond to the
paging identifier set(s) 114 for which the paging message 428 is
intended. In one example, the paging identifier set value may be a
two-byte field capable of indexing 2.sup.16 paging identifier sets
114. In another example, the paging identifier set value may be
included in a physical layer (PHY) preamble of the paging message
428. The stations 106 may be assigned or given information about
the paging identifier set value(s) that refer to paging identifier
sets 114 corresponding to the stations 106. Accordingly, stations
106 may receive the paging message 428. A station 106 may determine
whether the paging message 428 corresponds to the station 106 based
on the paging identifier set value(s) in the paging message 428.
For example, if the paging message 428 includes a paging identifier
set value for a paging identifier set 114 corresponding to the
station 106, the station 106 determines the paging message 428
corresponds to the station 106. Further, if the paging message 428
does not include a paging identifier set value for a paging
identifier set 114 corresponding to the station 106, the station
106 determines that the paging message 428 does not correspond to
the station 106.
[0171] In another example, the access point 104 may be configured
to transmit N paging messages 428 in sequence (where N is any
positive integer), in order to page the stations 106 at a given
time. Accordingly, each paging message 428 in the sequence may be
associated with a sequence number n in the N paging messages (n=1,
. . . , N). Each sequence number n may be associated with one or
more paging identifier sets 114.
[0172] Accordingly, the station 106 may determine the paging
message 428 corresponds to the station 106 based on the sequence
number n of the paging message 428. For example, if the sequence
number n of the paging message 428 is associated with a paging
identifier set 114 that includes a paging identifier 116 of the
station 106, the station 106 determines the paging message 428
corresponds to the station 106. Further, if the sequence number n
of the paging message 428 is not associated with a paging
identifier set 114 that includes a paging identifier 116 of the
station 106, the station 106 determines that the paging message 428
does not correspond to the station 106.
[0173] In some configurations, the station 106 may be assigned or
given information regarding the relationship or association between
sequence numbers and paging identifier sets 114. This may enable a
station 106 to listen for paging messages 428 with paging
identifier set(s) 114 that correspond to the station 106. For
example, the sequence number(s) n of the paging message(s) for the
paging identifier set(s) 114 corresponding to the station 106 may
be transmitted by the access point 104. The station 106 may listen
for the sequence number(s). In some cases and/or configurations,
the access point 104 may associate paging identifier sets 114 with
sequence numbers. As described above, a paging identifier set value
may correspond to a paging identifier set 114. Further, the station
106 may determine whether a paging identifier set 114 is associated
with a sequence number n based on the paging identifier set value.
For example, if the paging identifier set value of the paging
identifier set 114 equals mod(n, 256), the paging identifier set
114 is associated with the sequence number n. If the value of the
paging identifier set value of the paging identifier set 114 does
not equal mod(n, 256), the paging identifier set 114 is not
associated with the sequence number n.
[0174] In some configurations, the access point 104 may be
configured to transmit paging messages 428 at certain times (e.g.,
at specific time intervals, which may repeat periodically).
Accordingly, each paging message 428 may be associated with a
particular time interval. Each time interval may be associated with
one or more paging identifier sets 114. In these configurations,
the station 106 may determine whether the paging message 428
corresponds to the station 106 based on the time interval during
which the paging message 428 is transmitted. For example, if the
time interval of the paging message 428 is associated with a paging
identifier set 114 that includes a paging identifier 116 of the
station 106, the station 106 determines the paging message 428
corresponds to the station 106. Further, if the time interval of
the paging message 428 is not associated with a paging identifier
set 114 that includes a paging identifier 116 of the station 106,
the station 106 determines the paging message 428 does not
correspond to the station 106.
[0175] In some configurations, the station 106 may be assigned or
given information regarding the relationship or association between
time intervals and paging identifier sets 114. This may enable the
station(s) 106 to listen for paging messages 428 with paging
identifier set(s) 114 that correspond to the station 106. In some
cases and/or configurations, the access point 104 may associate
paging identifier sets 114 with time intervals. Further, the
station 106 may determine whether a given paging message 428
corresponds to the station 106 based on the time interval. If the
station 106 determines that the paging message 428 corresponds to
the station 106, the station 106 may further determine whether the
station 106 is paged. The station 106 may set itself to a
particular state (e.g., an awake state) if the station 106 is
paged. This may be accomplished based on the content of the paging
message 428 as described below.
[0176] FIG. 5 is a diagram illustrating examples 532a-c of paging
messages 528a-c in accordance with the systems and methods
disclosed herein. Example A 532a illustrates paging message A 528a.
As illustrated, paging message A 528a includes a bitmap 534 of N
bits (where N may be any positive integer). Each bit (e.g., bit
position) in the bitmap 534 may correspond to a particular paging
identifier 116 (e.g., station 106) of the stations 106 that are
associated with the paging identifier set(s) 114 associated with
the paging message A 528a. Further, the value of each bit (e.g., 0
or 1) may indicate or direct a state (e.g., doze or awake) of the
station 106 with the corresponding paging identifier 116.
Accordingly, the station 106 may determine its operational state by
determining the value of its corresponding bit in the bitmap
534.
[0177] In some configurations, the station 106 may be assigned or
given information from the access point 104 regarding which bit
position(s) in the bitmap 534 is associated with the paging
identifier(s) 116 of the station 106. For example, associations
between bit positions and paging identifiers 116 may be set by the
access point 104 or another device in the wireless communication
system 100 and communicated to the station 106 via a message (e.g.,
a management message).
[0178] In other configurations, the paging identifier sets 114 may
be associated with paging identifier set values that represent a
starting address for each of the paging identifiers 116 in the
paging identifier set 114. For example, if the paging identifiers
116 in a paging identifier set 114 are sequential (e.g., 11, 12,
13, 14, etc.), the paging identifier set 114 identifier may be 10.
Accordingly, the remaining portion of a paging identifier 116 that
is not part of the paging identifier set value may be used as an
index to the bitmap 534. Thus, a station 106 may use associated
paging identifier(s) 116 and index the bitmap 534 to determine the
directed operation state of the station 106. Continuing the above
example, if the station 106 is associated with paging identifier
value of 11, it may look for the value of the bit at position 1 in
the bitmap 534 to determine the directed operation state of the
station 106. In some aspects, the bit in position N of the bitmap
534 refers to the stations 106 with a paging identifier
value=N+256*paging identifier set value.
[0179] Example B 532b illustrates paging message B 528b. As
illustrated, paging message B 528b may include an explicit
identifier 536 of a paging identifier 116 corresponding to a
station 106. Examples of the explicit identifier 536 include a
value, string of bits, code, alphanumeric string (e.g., an absolute
address such as a local or global internet protocol (IP) address or
a local or global media access control (MAC) address of the
stations 106). In some configurations, the explicit identifier 536
may be an AID. Based on the explicit identifier, a station 106
corresponding to the paging identifier set(s) 114 associated with
the paging message B 528b that has determined that the paging
message B 528b corresponds to the station 106 may further determine
if the station 106 is paged. For example, if the paging message B
528b includes an explicit identifier 536 of a paging identifier 116
associated with the station 106, the station 106 determines that
the station 106 is paged. If the paging message B 528b does not
include an explicit identifier 536 of a paging identifier 116
associated with the station 106, the station 106 determines that it
106 is not paged.
[0180] Example C 532c illustrates paging message C 528c. As
illustrated, paging message C 528c may include no explicit
indication of the paging identifiers 116 associated with stations
106 to be paged. Rather, the stations 106 that are associated with
the paging identifier set(s) 114 associated with the paging message
C 528c may determine that they stations 106 are paged (implicitly).
Accordingly, the paging message C 528c implicitly indicates paging
for all paging identifiers 116 in the paging identifier set(s) 114
associated with the paging message C 528c. In some configurations,
a single bit may be included in paging message C 528c to indicate
or direct the operational state (e.g., awake or doze) of all
stations 106 associated with the paging identifier set(s) 114
associated with the paging message C 528c. For example, the value
of the bit (0 or 1) indicates the state of all stations 106 with
paging identifiers 116 included in the paging identifier set(s) 114
corresponding to paging message C 528c. In another configuration,
presence of the bit in the paging message C 528c (e.g., whether the
paging message C 528c includes the bit or not) may indicate or
direct the state of the stations 106. Accordingly, based on the
above messaging schemes and techniques, reduced overhead paging may
be achieved in the wireless communication network 100.
[0181] FIG. 6 is a block diagram illustrating one example of
station 606 elements that may be implemented for reduced overhead
paging. One or more of the elements 622, 638, 640, 642 may be
included within the station 106 described above in connection with
FIG. 1. The station 606 includes a receive chain 622 for receiving
a plurality of paging messages from another wireless device such as
the access point 104. The receive chain 622 may be configured to
perform one or more of the functions of the station receive chain
122 described above in connection with FIG. 1.
[0182] The station 606 further includes a paging message
correspondence determination block/module 638 for determining
whether one or more of the paging messages correspond to the
station 606 based on at least one paging identifier set 114. For
example, the paging message correspondence determination
block/module 638 may be configured to perform one or more of the
functions described above with respect to step 306 illustrated in
FIG. 3. In some configurations, the paging message correspondence
determination block/module 638 may be implemented with a processor
and instructions stored in memory.
[0183] The station 606 further includes a paging determination
block/module 640 for determining whether the station 606 is paged.
The paging determination block/module 640 may be configured to
perform one or more of the functions described above with respect
to step 308 illustrated in FIG. 3. In some configurations, the
paging determination block/module 640 may be implemented with a
processor and instructions stored in memory. The station 606
further includes a state controller 642 for setting the operational
state of the station 606. The state controller 642 may be
configured to perform one or more of the functions described above
with respect to step 310 illustrated in FIG. 3. In some
configurations, the state controller 642 may be implemented with a
processor and instructions stored in memory. In some
configurations, the paging correspondence determination
block/module 638, the paging determination block/module 640 and/or
the state controller 642 may be included in and/or coupled to the
station paging block/module 126 described in connection with FIG.
1.
[0184] As described above, paging identifiers 116 and paging
identifier sets 114 may be assigned and generated (by partitioning,
for example) by the access point 104. In some configurations, the
access point 104 may perform these operations based on information
from the station 106 about when the station 106 requests such
pages. This may lead to significant overhead at the access point
104 for performing such scheduling to accommodate requests of
multiple stations 106.
[0185] In some configurations, additionally or alternatively, the
access point 104 may transmit paging messages for particular paging
identifiers 116 at specific time intervals. For example, a paging
message comprising a bitmap of particular paging identifiers 116
may be transmitted at specific timer intervals. Other paging
messages may include bitmaps for different paging identifiers 116
and may be transmitted at different intervals. For example, a first
paging message may include a bitmap for a first paging identifier
set 114 (e.g., paging identifiers 1-32). The first paging message
may be transmitted once per three beacons (e.g., beacon 1, 4, 7,
etc.). Further, a second paging message may include a bitmap for a
second paging identifier set 114 (e.g., paging identifiers 33-64).
The second paging message may be transmitted once per three beacons
following the first paging message (e.g., beacon 2, 5, 8, etc.)
Further, a third paging message may include a bitmap for a third
paging identifier set 114 (e.g., paging identifiers 65-96). The
third paging message may be transmitted once per three beacons
following the second paging message (e.g., beacon 3, 6, 9, etc.). A
station 106 may be assigned a paging identifier 116 from the access
point 104 (e.g., a paging identifier 116 in either the first,
second, or third paging identifier set 114) that is transmitted
according to a particular schedule (e.g., interval schedule).
Accordingly, the station 106 may be assigned a particular paging
message transmission schedule from a finite group of schedules.
This information can further be used as a timing source for the
station 106 and reduces overhead at the access point 104. In some
configurations, the station 106 may request a paging message
schedule assignment. For example, the access point 104 and the
station 106 may agree to a particular paging message schedule.
[0186] In some configurations, after receiving a paging message
from the access point 104 indicating the access point 104 has data
for the station 106, the station 106 may send a polling message to
the access point 104 in order to receive the data from the access
point 104. In some aspects, multiple stations 106 may be paged by
the access point 104 as described above. Accordingly, the multiple
stations 106 may contend for one or more communication channels
with the access point 104 in order to transmit the polling messages
to the access point 104. If several stations 106 attempt to send
polling messages to access points such as the access point 104 at
the same time, the polling messages may collide. In some
configurations, the schedule of when the station 106 transmits a
polling message may be based on the paging identifier 116 of the
station 106 and/or the paging identifier set 114(s) to which the
station 106 belongs in order to reduce the likelihood of collisions
as described below.
[0187] In one configuration, a station 606 may determine when to
poll the access point 104 for data based on the paging identifier
116 of the station 106 upon receiving a paging message indicating
that the access point 104 has data for the station 106. For
example, as described above with respect to example A 532a in FIG.
5, the paging message may include a bitmap of N bits (where N is
any positive integer). Each bit in the bitmap may correspond to a
particular paging identifier 116 or station 106 of the stations 106
that are associated with the paging identifier set(s) 114
associated with the paging message. Further, the value of each bit
(e.g., 0 or 1) may indicate the state the corresponding station 106
with such a paging identifier 116 should be in (e.g., doze or
awake). Stations 106 associated with a bit having a value of 1 may
determine that the station 606 is paged (e.g., the access point 104
has data to transmit to the station 106) based on the bit value. In
some configurations, the station 106 may determine a time to poll
the access point 104 based on the position of the bit corresponding
to the station 106 in the bitmap. For example, if the bit
associated with the station 106 is the x.sup.th bit, the station
106 may poll the access point 104 at a time based on a function of
x (e.g., x*n microseconds (.mu.s) after receiving the paging
message, where n is any positive integer). In another example, the
station 106 may determine a time to poll the access point 104 based
on a hash function of the paging identifier 116 (e.g., a hash of
the paging identifier 116 and the timestamp of the paging
message).
[0188] In another configuration, the station 106 may determine a
time to start contending for a channel to transmit a polling
message to the access point 104 based on the paging identifier 116
(instead of determining an exact time to poll the access point 104,
for example). For instance, if the bit associated with the station
106 is the x.sup.th bit, the station 106 may contend for the
channel at a time based on a function of x (e.g., x*n .mu.s after
receiving the paging message, where n is any positive integer). In
another example, the station 106 may determine a time to contend
for the channel based on a hash function of the paging identifier
116 (e.g., a hash of the paging identifier 116 and the timestamp of
the paging message).
[0189] In yet another configuration, the station 106 may use a
backoff counter (similar to the backoff counter of the IEEE 802.11
standard) to determine when to transmit a polling message to the
access point 104. For example, the station 106 may countdown a
backoff counter from a starting value, and when the counter reaches
0, the station 106 may transmit the polling message. The station
106 may also determine if the channel is active (there is traffic
on the channel) or the channel is idle (there is no traffic on the
channel) while counting down. If the channel is active, the station
106 may freeze the countdown until the channel is idle again. The
station 106 may determine the starting value of the backoff counter
based on the paging identifier 116. For example, if the bit
associated with the station 106 is the x.sup.th bit, the station
106 may set the backoff counter at a value based on a function of x
(e.g., x*n .mu.s after receiving the paging message, where n is any
positive integer). In another example, the station 106 may set the
backoff counter at a value based on a hash function of the paging
identifier 116 (e.g., a hash of the paging identifier 116 and the
timestamp of the paging message).
[0190] The use of paging identifiers 116 and paging identifier sets
114 for transmitting and receiving paging messages as described
above may be performed through message exchange between the
stations 106 and the access point 104. The messages may take a
variety of different formats. Below are described some of the
formats that different messages may take and the usage of such
messages with respect to the aspects described herein.
[0191] FIG. 7 illustrates one example of a frame format for a
message 700. The message 700 may be transmitted from the station
106 to the access point 104 to set up paging intervals and/or
obtain a paging identifier 116. The message 700 may be referred to
as a page setup request message 700. As shown in FIG. 7, the
message 700 includes an equipment identifier (EID) field 744
comprising 1 byte, followed by a frame length (LEN) field 746
comprising 1 byte, followed by a control field 748 comprising 1
byte, followed by one or more time start fields 750a-b and time
period fields 752a-b, each comprising at least 3 bytes. The time
start fields 750a-b indicate a time the station 106 requests a
paging interval to start (a time period where the station 106 will
wake up) and the time period fields 752a-b indicate a time period
for the paging intervals. The times may be indicative of, for
example, a number of beacon periods, a number of seconds, a number
of microseconds, a multiple of a number of microseconds, or some
other unit of measure. The control field 748 may indicate the
manner in which the time is indicated. The response from the access
point 104 to the message 700 may be a page setup response message
or an acknowledgement (ACK) (e.g., an enhanced ACK with a time
indication).
[0192] FIG. 8 illustrates another example of a frame format for a
message 800. The message 800 may be transmitted from the station
106 to the access point 104 to set up paging intervals and/or
obtain a paging identifier 116. The message 800 includes the same
fields as the message 700 described in connection with FIG. 7
(e.g., an EID field 844, a LEN field 846, a control field 848, one
or more time start fields 850a-b and one or more time period fields
852a-b). However, the message 800 further includes one or more
paging identifier (PID) (e.g., paging identifier 116) fields 854a-b
comprising 2 bytes before each time start field 850a-b and time
period field 852a-b. The PID field 854 may indicate a specific
paging identifier 116 the station 106 requests for scheduling
during the associated time start and time period.
[0193] FIG. 9 illustrates another example of a frame format for a
message 900. The message 900 may be transmitted from the access
point 104 to the station 106. The message 900 may be referred to as
a page setup response message 900. The message 900 may be sent by
the access point 104 in response to receipt of a message (e.g., the
message 700 in FIG. 7 or the message 800 in FIG. 8) from the
station 106. The message 900 may include similar fields (e.g., an
EID field 944, a LEN field 946, a control field 948, one or more
time start fields 950a-b, one or more time period fields 952a-b and
one or more PID fields 954a-b) to those included in the message 800
described in connection with FIG. 8. The control field 948 may be
used to indicate the status (e.g., denied, accepted) of the request
for a paging interval and/or paging identifier 116 from the station
106. The time start field 950 may indicate an assigned start time
for paging intervals, the time period field 952 may indicate the
duration of the interval, and the PID field 954 may indicate the
paging identifier 116 assigned for the given start time and
interval. The station 106 may respond to receipt of the message 900
with transmission of an ACK.
[0194] FIG. 10 illustrates another example of a paging message
1000. The paging message 1000 may be similar to paging message A
528a described in connection with FIG. 5. As illustrated, the
paging message 1000 includes an EID field 1044, a LEN field 1046, a
control field 1048, and one or more offset fields 1056a-b and
optionally one or more bitmaps (BMAP) 1058a-b. The offset field
1056 may indicate the offset from the paging identifier 116 that
the station 106 should use to index the bitmap 1058 as described
above with respect to example A 532a described in connection with
FIG. 5. For example, an offset of 100 may indicate that the paging
identifier 101 is at the 1 position (101-100) of the bitmap. In
another aspect, the offset field may indicate the paging identifier
set 114 that is paged.
[0195] FIG. 11 illustrates another example of a paging message
1100. The paging message 1100 may be similar to paging message B
528b described in connection with FIG. 5. As illustrated, the
paging message 1100 includes an EID field 1144, a LEN field 1146, a
control field 1148, and one or more PID fields 1154a-n comprising a
paging identifier list. Each paging identifier field 1154 may
include or indicate a particular paging identifier 116, and the
station 106 may determine that the station 106 is paged if its
paging identifier 116 is listed in one of the PID fields 1154a-n,
as described above with example B 532b in connection with FIG.
5.
[0196] FIG. 12 is a diagram illustrating a more specific example of
a paging message 1228. A full bitmap (in accordance with known
approaches, e.g., a full TIM) may include a sequence of 0/1 bits
indicating whether there is data for a specific station. The index
of the station in that case is the position of the bit in the
bitmap (e.g., if the corresponding bit is 1, then there is data for
the station and if the corresponding bit is 0, then there is no
data for the station). In accordance with the systems and methods
disclosed herein, a bitmap may be compressed in order to obtain a
compressed paging message (as illustrated in FIG. 12, for example).
Example A 1232a illustrates a paging message 1228 with a compressed
bitmap, such as a compressed version of a traffic identification
map (TIM). The paging message 1228 may be similar to paging message
B 528b described in connection with FIG. 5. As illustrated, the
paging message 1228 includes an EID field 1244, a LEN field 1246,
an optional control field 1248, and one or more sub-bitmap elements
1260a-n. The control field 1248 may indicate the type of
compression used. The one or more sub-bitmap elements 1260a-n may
be sent in a single paging message (or frame) in order to cover
multiple stations 106.
[0197] Example B 1232b illustrates the structure of one of the
sub-bitmap elements 1260. In particular, a first field indicates an
offset value 1262 that is used to identify the index of a paged
station 106. In one configuration, the first field comprises 13
bits. A sub-bitmap element 1260 may identify a particular station.
For example, a station (e.g., paged station) index may be computed
as a sum of the offset value and the bit position in a
variable-length bitmap 1266. A second field identifies the length
1264 of the variable-length bitmap 1266. The length 1264 may be
indicated in byte units. In one configuration, the second field
comprises 3 bits. If the value of the length 1264 is equal to zero,
then the only station 106 that is paged is the station 106 with
index equal to the offset value 1262 contained in the first field.
If the value of the length 1264 is greater than zero, then the
value of the length 1264 indicates the number of bytes in the
variable-length bitmap 1266. A third field identifies the
variable-length bitmap 1266. The variable-length bitmap 1266 is of
variable length because trailing zeros can be omitted and assumed
to be implicitly zeros (unless another sub-bitmap element 1260
indicates otherwise). In one configuration, the length of the
variable-length bitmap may be from 0 bytes to 7 bytes. In another
configuration, the value indicated by the length field may be
mapped to different lengths of the variable length bitmap 1266. For
example, 0 may indicate that the variable length bitmap 1266 is not
present, 1 may indicate that the variable length bitmap 1266 is 1
byte, 2 may indicate that the variable length bitmap 1266 is 4
bytes, 3 may indicate that the variable length is 8 bytes, etc. It
should be noted that the compression described in connection with
FIG. 12 may be applied in conjunction with one or more of the
methods, procedures, approaches and/or structures described herein.
Additionally, all or part of the compression as described in
connection with FIG. 12 may be combined with one or more of the
methods, procedures, approaches and/or structures described
herein.
[0198] FIG. 13 illustrates another more specific example of a
paging message 1328. In particular, example A 1332a illustrates a
paging message 1328 including a compressed bitmap, such as a
compressed version of a traffic identification map (TIM) as
described above. By way of example, and not limitation, compression
applied in this paging message 1328 may be used with a low-density
bitmap (e.g., a bitmap in which the number of ones is much less
than the number of zeros). The paging message 1328 may be similar
to paging message B 528b described in connection with FIG. 5 above.
As illustrated, the paging message 1328 includes an EID field 1344,
a LEN field 1346, a control field 1348 and a compressed TIM
Information Element (TIM IE) 1368. The control field 1348 may
indicate the type of compression used.
[0199] Example B 1332b illustrates the structure of the compressed
TIM IE 1368. The structure employs running length sequences 1376
obtained by use of a running-length encoding (RLE) method to
process the original bitmap. In particular, a first field 1370
indicates the value of the first bit in the sequence of a bitmap to
be compressed. This value may be either "1" or "0". A second field
1372 indicates a number N of running length sequences (e.g.,
N=2.sup.n, where n is the number of bits included in the second
field 1372). In one aspect, the second field 1372 is formed of n=13
bits (in this way, N can cover at least up to 6000, for example). A
third field 1374 indicates the number of bits L of each running
length sequence (e.g., L=2.sup.l, where l is the number of bits
forming the third field 1374). In one aspect, the third field 1374
is formed of 1=4 bits. A fourth field 1376 includes the running
lengths sequences 1376. The total number of bits forming fourth
field 1376 is N*L. In one aspect, the number of bits L may be
selected as L=ceil(log.sub.2 R), where R=max([r1, r2, . . . , rN]),
with [r1, r2, . . . , rN] corresponding to the sequence of the N
running length sequences. From this compressed TIM IE 1368, the
stations can losslessly reconstruct the original bitmap. The
approach described in connection with FIG. 13 may operate in
conjunction with one or more of the methods, procedures, approaches
and/or structures described herein. Additionally, all or part of
the approach as described in connection with FIG. 13 may be
combined with one or more of the methods, procedures, approaches
and/or structures described herein.
[0200] FIG. 14 is a diagram illustrating one example of a paging
mechanism. The paging mechanism shown may be used by the access
point 104 and stations 106 in the wireless communication system 100
described in connection with FIG. 1. As illustrated, time increases
from left to right over the time axis 1484. The access point 104
may be configured to transmit a plurality of paging messages
1478a-b. By way of example and not limitation, a paging message
1478a may comprise a sequence of bits as illustrated. The paging
message 1478 may be generated as described above.
[0201] After transmission of a paging message 1478, a time interval
1482 may be reserved for the paged stations 106. The reservation
may be achieved by transmitting a message (e.g., a paging message,
other message) to cause non-paged stations to defer access to the
medium for the duration of the reserved period. In some
implementations, the deferred access can be achieved by setting a
duration field value of a reserving frame so that non-paged
stations can set their network allocation vector (NAV). In other
words, an access point 104 may determine a reserved time interval
and may set the reserved time interval for at least one paged
station 106 by setting a NAV.
[0202] During the reserved time interval 1482, the paged stations
106 can send requests 1480a-b to the access point 104 (e.g., Power
Saving polls (PS-POLL) requests) and receive a response from the
access point 104. Multiple paged stations 106 can contend during
time interval 1482 in accordance with various methods, as described
herein. Stations 106 that have not been paged may not contend
during time interval 1482. Once the time interval 1482 is over,
stations 106 may start contending to send requests to the access
point 104. The access point 104 determines the duration of the time
interval 1482. The time interval 1482 may be sufficient for all the
paged stations 106 to send requests to the access point 104 and
receive a response from the access point 104. By way of example,
and not limitation, the duration of time interval 1482 may be a
function of the number of paged stations 106.
[0203] FIG. 15 is a flow diagram illustrating one configuration of
a method 1500 for determining an operational state. In some
configurations, a station 106 described in connection with FIG. 1
may perform the method 1500. The station 106 may receive 1502 a
plurality of paging messages from the access point 104.
[0204] The station 106 may determine 1504 whether to listen to one
or more paging messages of the plurality of paging messages based
on the techniques described herein (e.g., based on a paging
identifier set). Determining 1504 whether to listen to one or more
paging messages may be one example of determining 306 whether a
paging message corresponds to the station 106 based on the at least
one paging identifier set as described above in connection with
FIG. 3. For instance, the station 106 may make the determination
1504 based on a paging identifier set 114 included in the paging
message, a sequence number n of the paging message or a time
interval in which the paging message was transmitted.
[0205] If the station 106 determines not to listen to one or more
paging messages, operation ends for those one or more paging
messages. However, if the station 106 determines to listen to one
or more paging messages, operation continues for those one or more
paging messages.
[0206] If the station 106 determines 1504 to listen to one or more
paging messages, the station 106 may determine 1506 whether the one
or more paging messages identifies an operational state of the
station 106 in accordance with the techniques described herein.
Determining 1506 whether the one or more paging messages identify
an operational state of the receiving device may be one example of
determining 308 whether the station 106 is paged as described in
connection with FIG. 3 above. For instance, the station 106 may
make the determination 1506 based on a bitmap included in the
paging message, a station identifier (e.g., a paging identifier or
some indication corresponding to the station 106) included in the
paging message or based on the paging message including no explicit
indicator. If the station 106 determines 1506 that the one or more
paging messages do not identify an operational state of the station
106, operation may end (but may recur for one or more additional
paging messages, for example).
[0207] If the station 106 determines 1506 that the one or more
paging messages identify an operational state of the station 106,
the station 106 may set 1508 its operational state based on the one
or more paging messages as described herein. For example, if the
one or more paging messages direct the station 106 to enter an
awake state, the station 106 may enter an awake state.
[0208] FIG. 16 is a flow diagram illustrating one configuration of
a method 1600 for compressing a paging message. By way of example
and not limitation, examples of possible compressed paging messages
that may be obtained in accordance with this method 1600 are paging
messages 1228 and 1328 as described above in connection with FIGS.
12 and 13. A transmitting device (e.g., the access point 104 or an
apparatus associated with the access point 104) may schedule 1602 a
plurality of receivers (e.g., stations 106) to be paged. The
transmitting device may generate 1604 a paging message. The paging
message may identify one or more of the plurality of scheduled
receivers.
[0209] The transmitting device may compress 1606 the paging
message. Various approaches may be employed for performing the
compression as described herein (through the use of paging
identifiers 116 and paging identifier sets 114, for example).
[0210] The transmitting device may transmit 1608 the compressed
paging message to the one or more of the plurality of scheduled
receivers. In certain cases (e.g., with high-density bitmap or a
bitmap in which the number of zeros is much less than the number of
ones), the transmitting device may choose a fraction (e.g.,
subgroup or subset) of the plurality of receivers to be paged for
inclusion in the paging message. In some configurations, scheduling
the plurality of devices may be done, for example, in a round robin
manner. The method 1600 described in connection with FIG. 16 may
operate in conjunction with one or more of the methods, procedures,
approaches and/or structures described herein. Additionally, all or
part of the method 1600 as described in connection with FIG. 16 may
be combined with one or more of the methods, procedures, approaches
and/or structures described herein.
[0211] FIG. 17 is a flow diagram illustrating another configuration
of a method 1700 for compressing a paging message. For example, the
method 1700 may be performed by an access point 104 in order to
generate the paging message 1228 described in connection with FIG.
12. The transmitting device (e.g., the access point 104 or an
apparatus associated with the access point 104) may define 1702 a
sub-bitmap element 1260.
[0212] The transmitting device may insert 1704 information directed
at identifying the index of a paged receiver (e.g., station 106)
into the sub-bitmap element 1260. The information may be, for
example, in the form of an offset field 1262 and a length field
1264 as described above in connection with FIG. 12.
[0213] The transmitting device may insert 1706 a variable-length
bitmap 1266 into the sub-bitmap element 1260. The transmitting
device may transmit 1708 one or more sub-bitmap elements 1260 in a
single paging message (within a single TIM frame, for example).
This may be done in order to cover multiple stations within a
single frame. The method 1700 described in connection with FIG. 17
may operate in conjunction with one or more of the methods,
procedures, approaches and/or structures described herein.
Additionally, all or part of the method 1700 as described in
connection with FIG. 17 may be combined with one or more of the
methods, procedures, approaches and/or structures described
herein.
[0214] FIG. 18 is a flow diagram illustrating another configuration
of a method 1800 for compressing a paging message. For example, the
method 1800 may be performed by an access point 104 in order to
generate the paging message 1328 described in connection with FIG.
13. The transmitting device (e.g., the access point 104 or an
apparatus associated with the access point 104) may receive 1802 a
bitmap to be compressed. The bitmap may be similar to the bitmap as
described above.
[0215] The transmitting device may compress 1804 the bitmap by
obtaining running-length sequences. The sequences may be obtained
by using a running-length encoding (RLE) technique.
[0216] The transmitting device may define 1806 an information
element (e.g., a compressed TIM IE 1368). The transmitting device
may insert 1808 the running length sequences into the information
element.
[0217] The transmitting device may insert 1810 information relative
to the running length sequences into the information element. For
example, the information may comprise the information contained in
the first bit field 1370, sequence length N field 1372 and length
of L field 1374 as described above in connection with FIG. 13. The
method 1800 described in connection with FIG. 18 may be used, for
example, with a low-density bitmap (e.g., a bitmap in which the
number of ones is much less than the number of zeros). However, it
should be noted that the method 1800 may be applied in other cases
or scenarios.
[0218] FIG. 19 is a flow diagram illustrating one configuration of
a method 1900 for receiving a compressed paging message. For
example, this method 1900 may be applicable to receive one or more
of the paging messages 1228 and 1328 described above in connection
with FIGS. 12 and 13. A receiver (e.g., a station 106) may receive
1902 a compressed paging message from a transmitting device (e.g.,
the access point 104 or an apparatus associated with the access
point 104).
[0219] The receiver may reconstruct 1904 a paging message based on
the compressed paging message. The approach for reconstructing the
paging message may depend on the approach used for compressing the
original paging message.
[0220] The receiver may select 1906 a first receiver identifier
from a plurality of receiver identifiers that are included in the
paging message. The receiver may transmit 1908 a request to the
transmitting device indicating the selection of the first receiver
identifier. The method 1900 described in connection with FIG. 19
may operate in conjunction with one or more of the methods,
procedures, approaches and/or structures described herein.
Additionally, all or part of the method 1900 as described in
connection with FIG. 19 may be combined with one or more of the
methods, procedures, approaches and/or structures described
herein.
[0221] During a TIM interval, contention may be performed by a set
of paged stations 106 that are scheduled for uplink transmission to
the access point 104, and a set of stations 106 that are non-paged
(which may still have packets to transmit to the access point 104).
The stations 106 may receive a paging indication that data is
pending at the access point for that station 106. Once the station
106 knows this, the station 106 may be configured to send a signal
to request the pending data. For example, the signal may include an
uplink frame called PS-POLL and/or other frame(s) to request that
pending data. As described above, if several stations 106 attempt
to send messages (e.g., polling messages) to an access point (e.g.,
access point 104) at the same time, the messages may collide.
Moreover, it may be desirable in some implementations to guarantee
access to the paged stations 106. Accordingly, in some aspects, a
schedule for station transmissions may be based on a paging
mechanism as described herein, in order to reduce the likelihood of
collision and guarantee access to the paged stations 106.
[0222] FIG. 20 is a flow diagram illustrating one configuration of
a method 2000 for paging receivers. A transmitting device (e.g.,
the access point 104 or an apparatus associated with the access
point 104) may determine 2002 a transmission schedule for a first
plurality of receivers (e.g., stations 106). The first plurality of
receivers may have data pending for transmission at the
transmitting device. The first plurality of receivers may be
selected from a second plurality of receivers. The signal may also
include scheduling information that may identify a transmission
schedule for the first plurality of receivers (e.g., the stations
106).
[0223] The transmitting device may determine 2004 a reserved time
interval. The reserved time interval may be reserved for the
scheduled first plurality of receivers. The transmitting device may
transmit 2006 a paging message to the second plurality of
receivers. For example, the paging message may include information
relative to the duration of the reserved time interval. The method
2000 described in connection with FIG. 20 may operate in
conjunction with one or more of the methods, procedures, approaches
and/or structures described herein. Additionally, all or part of
the method 2000 as described in connection with FIG. 20 may be
combined with one or more of the methods, procedures, approaches
and/or structures described herein.
[0224] FIG. 21 is a flow diagram illustrating one configuration of
a method 2100 for contention among receivers. Receivers (e.g.,
stations 106) may receive 2102 a paging message from a transmitting
device (e.g., the access point 104 or an apparatus associated with
the access point 104).
[0225] Each receiver may obtain 2104 information relative to a
reserved time interval (e.g., to the duration of the reserved time
interval). For example, each receiver may obtain 2104 this
information in a management frame, paging frame or other signaling.
As described above, in some implementations, the reservation may be
achieved by having the paging message (or an additional message
sent after the initial paging message, for example) to cause
non-paged stations to defer access to the medium for the duration
of the reserved period. The deferred access can be achieved, for
example, by setting a duration field of the paging message or
reserving frame so that non-paged stations may set their NAV for
the appropriate time.
[0226] Each receiver may determine 2106 whether it is a paged
receiver based on the content of the paging message. For example,
during the reserved time interval, only paged receivers may contend
to send requests (e.g. PS-POLL requests) to the transmitting
device. Paged receivers may contend 2108 to send a request (to the
transmitting device, for example).
[0227] Non-paged receivers may wait 2110 for expiry of the reserved
time interval. The receiver(s) may contend 2112 to send a frame
upon expiry of the reserved time interval. The method 2100
described in connection with FIG. 21 may operate in conjunction
with one or more of the methods, procedures, approaches and/or
structures described herein. Additionally, all or part of the
method 2100 as described in connection with FIG. 21 may be combined
with one or more of the methods, procedures, approaches and/or
structures described herein.
[0228] Various approaches for medium contention may be envisaged to
be used by the receivers in any of the methods and processes
described above. By way of example and not limitation, contention
may be employed in conjunction with the method 2100 described in
connection with FIG. 21.
[0229] A paging message (as described in connection with any of the
methods above, for example) may implicitly or explicitly define an
ordering for the stations 106. For example, if the TIM bitmap
indicates that both station 1 and station 2 are paged, then the TIM
bitmap may also implicitly or explicitly indicate whether station 1
is before or after station 2. For instance, the order may be
determined by the order in which the paged stations appear in the
bitmap representation. Consider a bitmap {0, 1, 0, 0, 1, 1}, where
the station 106 associated with the bit in position 2 is assumed to
be before the station associated with the bit in position 5. Thus,
a schedule indicated by the access point 104 and/or determined by a
station 106 may indicate an order. In some configurations, the
ordering for the stations may be randomized (based on a TSF or
other indications, for example).
[0230] In some implementations, the compressed bitmap may be
expressed as a list of station identifiers. In this case, the
sequence in which the station identifiers appear in the list may
determine the order. Consider the list {13, 25, 5, 22}, where the
station associated with identifier "13" is assumed to come before
station identified by "5." In another configuration, the order may
be derived from the value of the station identifier irrespective of
the message representation.
[0231] In some implementations, the position of the station within
the TIM bitmap sequence may be a function of the position of the
station 106 as described above. The order may further be dependent
on other indications, the indications being either included in the
paging message or assumed to be known at the stations 106. For
example, the indication may include the Timing Synchronization
Function (TSF) within the paging message. In such an
implementation, the first station 106 may be the one whose
identifier is set to "1" and has a position within the TIM bitmap
sequence that is first in the order after the position associated
with the 12 least significant bits (LSBs) of the TSF. Many other
functions incorporating various indications may be included to
achieve a similar result as that based on the TSF. One beneficial
result of including the TSF in the computation of the order is that
the order may be changed at each transmission, provided that the
portion of the used TSF is different at each transmission.
[0232] In some implementations, the sender of the paging message
may determine the order of the paged stations according to any
criteria including the usage of the ordering information. For
example, the sender may order the stations based on their Quality
of Service (QoS) requirements, power saving requirements or other
performance parameters. It may be desirable, in some
implementations, for the sender of the paging message to include in
the message an explicit indication of the order. This explicit
indication of the order may not be based on the TIM bitmap but
rather other factors as described above.
[0233] A further approach includes assigning to a station 106 a
deterministic back-off value. The station may be configured to use
the backoff value to initialize a backoff counter for the
distributed coordination function/enhanced distributed channel
access (DCF/EDCA) access procedure. The initial value of the
backoff counter may be based on the order of the paged station. The
order of the paged station may be obtained using one or more of the
approaches and/or methods described above.
[0234] A further approach includes assigning to each paged station
106 a time at which to start the contention procedure for sending
the PS-POLL. In one configuration, the contention procedure may
start for all stations 106 at a defined time, for instance,
immediately after the end of the paging message or after an
additional message sent after the paging message (e.g., the message
reserving the medium described above). In some implementations, the
start of the contention may be set to a different time per each
station 106. For instance, the time a station is allowed to start
the contention to send the PS-POLL may be determined based on the
order of the stations defined by the paging message as described
above. In one implementation, a time slot may be defined and a
station 106 may be allowed to start the contention after a time
that is a multiple of time slots times the position of the station
106. The time slot may be, for instance, known by all the stations
106 a priori or communicated by the sender of the paging message.
The interval between subsequent devices in the order may correspond
to the beacon interval or the number of TIM bitmap sequence bits
that are set to "1." Alternatively, the interval may be a fixed
time during which a typical PS-POLL or Data or ACK exchange could
take place. In further aspects, after entering an awake state,
stations 106 may sense or listen to the medium for an additional
time prior to contending for the medium.
[0235] In some implementations, the system may be configured to
assign to a station 106 a precise time slot to access the medium.
In this aspect, the station may be configured to send the PS-POLL
at the designated time. The assignment of the time slot may be
based on the position of the station identifier within the paging
message.
[0236] Another approach includes assigning to one or all the
stations 106 a Contention Window (CW) value. The station 106 may be
configured to use the CW value as described by the DCF/EDCA medium
access procedure. In one implementation, all the paged stations 106
may be configured to use the same CW value when contending for
sending the PS-POLL after the paging message. The CW value may be a
function of the number of stations paged by the paging message. For
instance, the CW may be larger if the number of paged stations is
large and may be smaller if the number of paged stations is small.
In another aspect, different stations may be assigned different CW
values, for instance, depending on the order indicated in the
paging message.
[0237] In some configurations, a station 106 may initialize a
backoff value based on the CW to determine when to contend for the
medium. For a first transmission, the initialized backoff value may
be a random number in an interval [0, CW]. However, if the station
106 is unable to successfully transmit the first transmission, an
N.sup.th transmission attempt may be initialized with a backoff
value having a random value within an interval of [0, N*CW] or [0,
N+CW]. Advantageously, the use of such backoff value intervals for
the N.sup.th transmission attempts may prevent use of a random
value within an exponentially based backoff value interval such as
[0, (2.sup.N)*CW]. Accordingly, the time until the station 106
successfully transmits a message may be shortened, and the station
106 may enter a doze state sooner and consume less power.
[0238] In some configurations, if a station 106 does not receive a
response to a PS-POLL, the station 106 may again transmit the PS
POLL in a current paging interval (e.g., one interval for
transmitting PS-POLLs). When the station 106 transmits the PS-POLL
again in the current paging interval, the station 106 may, for
example, send the PS-POLL a point coordination function (PCF)
interframe space (PIFS) time after the previous PS-POLL or the
station 106 may use a back-off procedure as described herein. On
the other hand, in some configurations, if the station 106 does not
receive a response to a PS-POLL, the station 106 may defer
transmission of the PS-POLL until a next paging interval (e.g.,
another interval for transmitting PS-POLLs different from the
current paging interval). It should be noted that two or more of
the access approaches described above (e.g., assignment of the
contention window, assignment of the initial backoff value and/or
assignment of the time for the contention start) may be used
concurrently.
[0239] FIG. 22 illustrates certain components that may be included
within a station 2206. One or more of the stations 106, 606
described above may be implemented in accordance with the station
2206 described in connection with FIG. 22. The station 2206
includes a processor 2215. The processor 2215 may be a general
purpose single- or multi-chip microprocessor (e.g., an ARM), a
special purpose microprocessor (e.g., a digital signal processor
(DSP)), a microcontroller, a programmable gate array, etc. The
processor 2215 may be referred to as a central processing unit
(CPU). Although just a single processor 2215 is shown in the
station 2206 of FIG. 22, in an alternative configuration, a
combination of processors (e.g., an ARM and DSP) could be used.
[0240] The station 2206 also includes memory 2201 in electronic
communication with the processor 2215 (i.e., the processor 2215 can
read information from and/or write information to the memory 2201).
The memory 2201 may be any electronic component capable of storing
electronic information. The memory 2201 may be random access memory
(RAM), read-only memory (ROM), magnetic disk storage media, optical
storage media, flash memory devices in RAM, on-board memory
included with the processor, programmable read-only memory (PROM),
erasable programmable read-only memory (EPROM), electrically
erasable PROM (EEPROM), registers, and so forth, including
combinations thereof.
[0241] Data 2203a and instructions 2205a may be stored in the
memory 2201. The instructions 2205a may include one or more
programs, routines, sub-routines, functions, procedures, etc. The
instructions 2205a may include a single computer-readable statement
or many computer-readable statements. The instructions 2205a may be
executable by the processor 2215 to implement one or more of the
methods 200, 300, 1500, 1600, 1700, 1800, 1900, 2000, 2100 that
were described above. Executing the instructions 2205a may involve
the use of the data 2203a that is stored in the memory 2201. FIG.
22 shows some instructions 2205b and data 2203b being loaded into
the processor 2215.
[0242] The station 2206 may also include a transmitter 2211 and a
receiver 2213 to allow transmission and reception of signals
between the station 2206 and a remote location (e.g., an access
point, base station or other wireless communication device). The
transmitter 2211 and receiver 2213 may be collectively referred to
as a transceiver 2209. An antenna 2207 may be electrically coupled
to the transceiver 2209. The station 2206 may also include (not
shown) multiple transmitters, multiple receivers, multiple
transceivers and/or multiple antenna.
[0243] The various components of the station 2206 may be coupled
together by one or more buses, which may include a power bus, a
control signal bus, a status signal bus, a data bus, etc. For
simplicity, the various buses are illustrated in FIG. 22 as a bus
system 2217.
[0244] In some configurations, the station 2206 may further
comprise a user interface. The user interface may comprise a
keypad, a microphone, a speaker, and/or a display. The user
interface may include any element or component that conveys
information to a user of the station 2206 and/or receives input
from the user.
[0245] FIG. 23 illustrates certain components that may be included
within an access point 2304. The access point 104 described above
may be implemented in accordance with the access point 2304
described in connection with FIG. 23. The access point 2304
includes a processor 2333. The processor 2333 may be a general
purpose single- or multi-chip microprocessor (e.g., an ARM), a
special purpose microprocessor (e.g., a digital signal processor
(DSP)), a programmable logic device (PLD), a controller, state
machine, gated logic, discrete hardware components, dedicated
hardware finite state machines, a microcontroller, a programmable
gate array, etc. The processor 2333 may be referred to as a central
processing unit (CPU). Although just a single processor 2333 is
shown in the access point 2304 of FIG. 23, in an alternative
configuration, a combination of processors (e.g., an ARM and DSP)
could be used.
[0246] The access point 2304 also includes memory 2319 in
electronic communication with the processor 2333 (i.e., the
processor 2333 can read information from and/or write information
to the memory 2319). The memory 2319 may be any electronic
component capable of storing electronic information. The memory
2319 may be random access memory (RAM), read-only memory (ROM),
magnetic disk storage media, optical storage media, flash memory
devices in RAM, on-board memory included with the processor,
programmable read-only memory (PROM), erasable programmable
read-only memory (EPROM), electrically erasable PROM (EEPROM),
registers, and so forth, including combinations thereof.
[0247] Data 2321a and instructions 2323a may be stored in the
memory 2319. The instructions 2323a may include one or more
programs, routines, sub-routines, functions, procedures, etc. The
instructions 2323a may include a single computer-readable statement
or many computer-readable statements. The instructions 2323a may be
executable by the processor 2333 to implement one or more of the
methods 200, 1600, 1700, 1800, 2000 described above. Executing the
instructions 2323a may involve the use of the data 2321a that is
stored in the memory 2319. FIG. 23 shows some instructions 2323b
and data 2321b being loaded into the processor 2333.
[0248] The access point 2304 may also include a transmitter 2329
and a receiver 2331 to allow transmission and reception of signals
between the access point 2304 and a remote location (e.g., a
wireless communication device, a station, etc.). The transmitter
2329 and receiver 2331 may be collectively referred to as a
transceiver 2327. An antenna 2325 may be electrically coupled to
the transceiver 2327. The access point 2304 may also include (not
shown) multiple transmitters, multiple receivers, multiple
transceivers and/or multiple antenna.
[0249] The various components of the access point 2304 may be
coupled together by one or more buses, which may include a power
bus, a control signal bus, a status signal bus, a data bus, etc.
For simplicity, the various buses are illustrated in FIG. 23 as a
bus system 2335.
[0250] In the above description, reference numbers may have been
used in connection with various terms. Where a term is used in
connection with a reference number, this may be meant to refer to a
specific element that is shown in one or more of the Figures. Where
a term is used without a reference number, this may be meant to
refer generally to the term without limitation to any particular
Figure.
[0251] The term "determining" encompasses a wide variety of actions
and, therefore, "determining" can include calculating, computing,
processing, deriving, investigating, looking up (e.g., looking up
in a table, a database or another data structure), ascertaining and
the like. Also, "determining" can include receiving (e.g.,
receiving information), accessing (e.g., accessing data in a
memory) and the like. Also, "determining" can include resolving,
selecting, choosing, establishing and the like.
[0252] The phrase "based on" does not mean "based only on," unless
expressly specified otherwise. In other words, the phrase "based
on" describes both "based only on" and "based at least on."
[0253] As used herein, a phrase referring to "at least one of" a
list of items refers to any combination of those items, including
single members. As an example, "at least one of: a, b, or c" is
intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c.
[0254] The various operations of methods described above may be
performed by any suitable means capable of performing the
operations, such as various hardware and/or software component(s),
circuits, and/or module(s). Generally, any operations illustrated
in the Figures may be performed by corresponding functional means
capable of performing the operations.
[0255] The various illustrative logical blocks, modules and
circuits described in connection with the present disclosure may be
implemented or performed with a general purpose processor, a
digital signal processor (DSP), an application specific integrated
circuit (ASIC), a field programmable gate array signal (FPGA) or
other programmable logic device (PLD), discrete gate or transistor
logic, discrete hardware components or any combination thereof
designed to perform the functions described herein. A general
purpose processor may be a microprocessor or any commercially
available processor, controller, microcontroller or state machine.
A processor may also be implemented as a combination of computing
devices (e.g., a combination of a DSP and a microprocessor, a
plurality of microprocessors, one or more microprocessors in
conjunction with a DSP core, or any other such configuration).
[0256] In one or more aspects, the functions described may be
implemented in hardware, software, firmware, or any combination
thereof. If implemented in software, the functions may be stored on
or transmitted over as one or more instructions or code on a
computer-readable medium.
[0257] The functions described herein may be stored as one or more
instructions on a processor-readable or computer-readable medium.
The term "computer-readable medium" refers to any available medium
that can be accessed by a computer or processor. By way of example,
and not limitation, such a medium may comprise RAM, ROM, EEPROM,
flash memory, CD-ROM or other optical disk storage, magnetic disk
storage or other magnetic storage devices, or any other medium that
can be used to store desired program code in the form of
instructions or data structures and that can be accessed by a
computer or processor. Disk and disc, as used herein, includes
compact disc (CD), laser disc, optical disc, digital versatile disc
(DVD), floppy disk and Blu-Ray.RTM. disc where disks usually
reproduce data magnetically, while discs reproduce data optically
with lasers. It should be noted that a computer-readable medium may
be tangible and non-transitory. The term "computer-program product"
refers to a computing device or processor in combination with code
or instructions (e.g., a "program") that may be executed, processed
or computed by the computing device or processor. As used herein,
the term "code" may refer to software, instructions, code or data
that is/are executable by a computing device or processor.
[0258] Software or instructions may also be transmitted over a
transmission medium. For example, if the software is transmitted
from a website, server, or other remote source using a coaxial
cable, fiber optic cable, twisted pair, digital subscriber line
(DSL), or wireless technologies such as infrared, radio, and
microwave, then the coaxial cable, fiber optic cable, twisted pair,
DSL, or wireless technologies such as infrared, radio, and
microwave are included in the definition of transmission
medium.
[0259] The methods disclosed herein comprise one or more steps or
actions for achieving the described method. The method steps and/or
actions may be interchanged with one another without departing from
the scope of the claims. In other words, unless a specific order of
steps or actions is required for proper operation of the method
that is being described, the order and/or use of specific steps
and/or actions may be modified without departing from the scope of
the claims.
[0260] It is to be understood that the claims are not limited to
the precise configuration and components illustrated above. Various
modifications, changes and variations may be made in the
arrangement, operation and details of the systems, methods, and
apparatus described herein without departing from the scope of the
claims.
* * * * *