Title of Invention

“DYNAMIC ENERGY SAVING MECHANISM FOR ACCESS POINTS”

Abstract Mobile access points typically run on batteries, and therefore, can operate for a limited amount of time without an external power source. However, because the access point service model requiring the access point to always be available and the access point’s limited battery capacity reduces the time that the mobile access point can be used. Functionality can be incorporated in mobile access points to implement power saving mechanisms by altering the service model that requires the access point to always be available. Configuring the access point to enter into a low powered state for a predefined period of time can conserve mobile access point power and prolong battery life.
Full Text FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
PROVISIONAL SPECIFICATION
(See section 10, rule 13)
“DYNAMIC ENERGY SAVING MECHANISM FOR ACCESS POINTS”
Applicant: ATHEROS COMMUNICATIONS, INC.
5480 Great America Pkwy.
Santa Clara, CA 95054
United States of America
The following specification particularly describes the invention and the manner in which
it is to be performed.
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FIELD OF INVENTION
[0001] Embodiments of the inventive subject matter generally relate to the field of
wireless communication networks, and more particularly, to a dynamic energy saving
mechanism for access points.
BACKGROUND ART
[0002] Access points enable communication devices to connect to and transmit
information via a communication network. Mobile access points allow for continuous
connectivity to the communication network (such as the Internet) without being
restrained by the coverage area of a fixed access point. However, because mobile access
points typically run on batteries, mobile access points can only operate for a limited
amount of time without an external power source.
SUMMARY OF THE INVENTION
[0003] Various embodiments are disclosed for reducing power consumption in an
access point. In one embodiment, the access point receives, from a station, a message
indicating a station sleep interval associated with the station. The station sleep interval
indicates a time interval in which the station will enter a sleep mode. Access point quiet
information comprising an access point sleep interval is calculated based, in part, on the
station sleep interval. The access point sleep interval indicates a time interval in which
the access point will enter a sleep mode. The access point quiet information is
transmitted to the station to prevent the station from initiating transmissions during the
access point sleep interval. A start of the access point sleep interval is determined based
on the access point quiet information. The sleep mode in the access point is initiated at
the start of the access point sleep interval.
[0004] Accordingly, the present invention relates to a method for reducing power
consumption in an access point, the method comprising: receiving a message at the
access point from a station, via a wireless communication channel, indicating a station
sleep interval associated with the station, wherein the station sleep interval indicates a
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time interval in which the station will enter a sleep mode; calculating access point quiet
information comprising an access point sleep interval based, at least in part, on the station
sleep interval, wherein the access point sleep interval indicates a time interval in which
the access point will enter a sleep mode; transmitting to the station, via the wireless
communication channel, a beacon indicating the access point quiet information to prevent
the station from initiating transmissions to the access point during the access point sleep
interval; determining, based on the access point quiet information, a start of the access
point sleep interval; and initiating the sleep mode in the access point at the start of the
access point sleep interval.
[0005] According to another aspect of the present invention, the access point quiet
information further comprises one or more of a time instant at which the access point
enters the sleep mode, a time instant at which the access point wakes up from the sleep
mode, and an indication of how often the access point enters the sleep mode.
[0006] According to yet another aspect of the present invention, the said method further
comprising: detecting, at the access point, a pending transmission associated with the
station, wherein the pending transmission comprises one of a data frame transmission and
a management frame transmission; calculating a transmission time associated with the
pending transmission; comparing the transmission time with an amount of time
remaining before the access point sleep interval begins; determining that the transmission
time is greater than the amount of time remaining before the access point sleep interval
begins; and preventing execution of the pending transmission associated with the station.
[0007] According to further aspect of the present invention, wherein the access point is
a mobile phone access point.
[0008] According to another aspect of the present invention, wherein said calculating
the access point quiet information comprises calculating an access point sleep interval
that initiates the sleep mode in the access point during the station sleep interval.
[0009] According to yet another aspect of the present invention, the said method further
comprising: determining that no stations are connected to the access point, via the
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wireless communication channel; calculating a second access point quiet information
comprising a second access point sleep interval based, at least in part, on a beacon
interval and on said determining that no stations are connected to the access point,
wherein the beacon interval indicates a time interval in which a beacon is transmitted,
and wherein the second access point sleep interval indicates a time interval in which the
access point will enter a sleep mode; transmitting, via the wireless communication
channel, a second beacon indicating the second access point quiet information to prevent
one or more stations from initiating transmissions to the access point during the second
access point sleep interval; determining, based on the second access point quiet
information, a start of the second access point sleep interval; initiating the sleep mode in
the access point at the start of the second access point sleep interval; determining, based
on the second access point quiet information, an end of the second access point sleep
interval; and initiating a normal operational mode, at the access point, in response to
determining the end of the second access point sleep interval.
[0010] According to further aspect of the present invention, he said method further
comprising: receiving a second message at the access point from a second station, via the
wireless communication channel, indicating a second station sleep interval associated
with the second station, wherein the second station sleep interval indicates a time interval
in which the second station will enter a sleep mode; calculating a second access point
quiet information comprising a second access point sleep interval based, at least in part,
on the first station sleep interval and the second station sleep interval, wherein the second
access point sleep interval indicates a time interval for which the access point will enter a
sleep mode; and transmitting to the first and the second stations, via the communication
channel, a second beacon indicating the second access point quiet information to prevent
the first and the second stations from initiating transmissions to the access point during
the second access point sleep interval.
[0011] According to another aspect of the present invention, wherein said calculating
the second access point quiet information comprises: determining a least common factor
between the station sleep interval associated with the first station and the second station
sleep interval associated with the second station; and determining when to initiate the
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second access point sleep interval based, at least in part, on said determining the least
common factor between the station sleep interval associated with the first station and the
second station sleep interval associated with the second station.
[0012] The present invention further relates to a method comprising: receiving access
point quiet information at a station from an access point, via a wireless communication
channel, wherein the access point quiet information comprises an access point sleep
interval indicating a time interval for which the access point will enter a sleep mode;
determining that the wireless communication channel is available for transmission of
information to the access point, wherein the transmission of information comprises one of
a data frame transmission and a management frame transmission; calculating a
transmission time associated with the transmission of information to the access point;
comparing the transmission time with an amount of time remaining before a station sleep
interval associated with the station begins, wherein the station sleep interval indicates a
time interval in which the station will enter a sleep mode; determining that the
transmission time is less than the amount of time that remains before the station sleep
interval begins; and transmitting the information to the access point.
[0013] According to another aspect of the present invention, the said method further
comprising: transmitting, to the access point, the station sleep interval associated with the
station, wherein the access point sleep interval is determined based, in part, on the station
sleep interval.
[0014] According to yet another aspect of the present invention, the said method further
comprising: determining, based on the station sleep interval, a start of the station sleep
interval; and initiating the sleep mode in the station at the start of the station sleep
interval.
[0015] According to further aspect of the present invention wherein said determining,
based on the station sleep interval, the start of the station sleep interval further comprises:
determining that a station sleep timer associated with the station is expired, wherein the
station sleep timer indicates an amount of time that remains before the station enters the
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sleep mode.
[0016] According to another aspect of the present invention, the said method further
comprising: storing, in a network allocation vector timer, associated with the station, the
access point sleep interval, wherein the network allocation vector timer indicates an
amount of time that remains before the station wakes up from the sleep mode;
determining that the network allocation vector timer associated with the station has
expired; and initiating a normal operational mode, at the station, in response to
determining that the network allocation vector timer associated with the station has
expired.
[0017] The present invention also relates to an access point device comprising: a
transceiver unit configured to receive a message from a station, via a wireless
communication channel, indicating a station sleep interval associated with the station,
wherein the station sleep interval indicates a time interval in which the station will enter a
sleep mode; a power saving unit configured to: calculate access point quiet information
comprising an access point sleep interval based, at least in part, on the station sleep
interval, wherein the access point sleep interval indicates a time interval in which the
access point will enter a sleep mode; transmit to the station, via the wireless
communication channel, a beacon indicating the access point quiet information to prevent
the station from initiating transmissions to the access point during the access point sleep
interval; determine, based on the access point quiet information, a start of the access point
sleep interval; and initiate the sleep mode in the access point at the start of the access
point sleep interval.
[0018] According to another aspect of the present invention, wherein the access point
quiet information further comprises one or more of a time instant at which the access
point enters the sleep mode, a time instant at which the access point wakes up from the
sleep mode, and an indication of how often the access point enters the sleep mode.
[0019] According yet another aspect of the present invention, the access point device
further comprising: the transceiver unit configured to: detect a pending transmission
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associated with the station, wherein the pending transmission comprises one of a data
frame transmission and a management frame transmission; the power saving unit
configured to: calculate a transmission time associated with the pending transmission;
compare the transmission time with an amount of time remaining before the access point
sleep interval begins; determine that the transmission time is greater than the amount of
time remaining before the access point sleep interval begins; and prevent execution of the
pending transmission associated with the station.
[0020] According to further aspect of the present invention, wherein the power saving
unit configured to calculate the access point quiet information further comprises the
power saving unit configured to calculate an access point sleep interval that initiates the
sleep mode in the access point during the station sleep interval.
[0021] According to another aspect of the present invention, the access point device
further comprising: the power saving unit configured to determine that no stations are
connected to the access point, via the wireless communication channel; calculate a
second access point quiet information comprising a second access point sleep interval
based, at least in part, on a beacon interval and on said determining that no stations are
connected to the access point, wherein the beacon interval indicates a time interval in
which a beacon is transmitted, and wherein the second access point sleep interval
indicates a time interval in which the access point will enter a sleep mode; transmit, via
the wireless communication channel, a second beacon indicating the second access point
quiet information to prevent one or more stations from initiating transmissions to the
access point during the second access point sleep interval; determine, based on the second
access point quiet information, a start of the second access point sleep interval; initiate
the sleep mode in the access point at the start of the second access point sleep interval;
determine, based on the second access point quiet information, an end of the second
access point sleep interval; and initiate a normal operational mode, at the access point, in
response to determining the end of the second access point sleep interval.
[0022] According to another aspect of the present invention, the access point device
further comprising: the transceiver unit configured to: receive a second message
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from a second station, via the wireless communication channel, indicating a second
station sleep interval associated with the second station, wherein the second station sleep
interval indicates a time interval in which the second station will enter a sleep mode; the
power saving unit configured to: calculate a second access point quiet information
comprising a second access point sleep interval based, at least in part, on the first station
sleep interval and the second station sleep interval, wherein the second access point sleep
interval indicates a time interval for which the access point will enter a sleep mode; and
transmit to the first and the second stations, via the communication channel, a second
beacon indicating the second access point quiet information to prevent the first and the
second stations from initiating transmissions to the access point during the second access
point sleep interval.
[0023] According to yet another aspect of the present invention, wherein the power
saving unit configured to calculate the second access point quiet information comprises
the power saving unit configured to: determine a least common factor between the station
sleep interval associated with the first station and the second station sleep interval
associated with the second station; and determine when to initiate the second access point
sleep interval based, at least in part, on said determining the least common factor between
the station sleep interval associated with the first station and the second station sleep
interval associated with the second station.
[0024] The present invention further relates to one or more machine-readable media,
having instructions stored therein, which when executed by a set of one or more
processors causes the set of one or more processors to perform operations that comprise:
receiving a message at the access point from a station, via a wireless communication
channel, indicating a station sleep interval associated with the station, wherein the station
sleep interval indicates a time interval in which the station will enter a sleep mode;
calculating access point quiet information comprising an access point sleep interval
based, at least in part, on the station sleep interval, wherein the access point sleep interval
indicates a time interval in which the access point will enter a sleep mode; transmitting to
the station, via the wireless communication channel, a beacon indicating the access point
quiet information to prevent the station from initiating transmissions to the access
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point during the access point sleep interval; determining, based on the access point quiet
information, a start of the access point sleep interval; and initiating the sleep mode in the
access point at the start of the access point sleep interval.
[0025] According to another aspect of the present invention, the access point quiet
information further comprises one or more of a time instant at which the access point
enters the sleep mode, a time instant at which the access point wakes up from the sleep
mode, and an indication of how often the access point enters the sleep mode.
[0026] According to yet another aspect of the present invention, the machine-readable
media further operable to perform: detecting, at the access point, a pending transmission
associated with the station, wherein the pending transmission comprises one of a data
frame transmission and a management frame transmission; calculating a transmission
time associated with the pending transmission; comparing the transmission time with an
amount of time remaining before the access point sleep interval begins; determining that
the transmission time is greater than the amount of time remaining before the access point
sleep interval begins; and preventing execution of the pending transmission associated
with the station.
[0027] According to further aspect of the present invention, the machine-readable
media further operable to perform: receiving a second message at the access point from a
second station, via the wireless communication channel, indicating a second station sleep
interval associated with the second station, wherein the second station sleep interval
indicates a time interval for which the second station will enter a sleep mode; calculating
a second access point quiet information comprising a second access point sleep interval
based, at least in part, on the first station sleep interval and the second station sleep
interval, wherein the second access point sleep interval indicates a time interval for which
the access point will enter a sleep mode; and transmitting to the first and the second
stations, via the communication channel, a second beacon indicating the second access
point quiet information to prevent the first and the second stations from initiating
transmissions to the access point during the second access point sleep interval.
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[0028] According to another aspect of the present invention, wherein said operation of
calculating the second access point quiet information further comprises: determining a
least common factor between the station sleep interval associated with the first station
and the second station sleep interval associated with the second station; and determining
when to initiate the second access point sleep interval based, at least in part, on said
determining the least common factor between the station sleep interval associated with
the first station and the second station sleep interval associated with the second station.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The present embodiments may be better understood, and numerous objects,
features, and advantages made apparent to those skilled in the art by referencing the
accompanying drawings.
[0030] Figure 1 is an example conceptual diagram illustrating network components
configured to enable energy conservation in an access point;
[0031] Figure 2 illustrates example frame formats for transmission of management
information;
[0032] Figure 3 depicts a flow diagram illustrating example operations for an access
point configuring a quiet interval;
[0033] Figure 4 depicts a flow diagram illustrating example operations for an access
point configuring a quiet interval;
[0034] Figure 5A is a timing diagram illustrating transmission operations when no
stations are connected to an access point;
[0035] Figure 5B is a timing diagram illustrating transmission operations for an access
point connected to a station;
[0036] Figure 6 depicts a flow diagram illustrating example operations for a station
connected to an access point;
[0037] Figure 7 depicts a flow diagram illustrating example operations for a station
connected to an access point; and
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[0038] Figure 8 depicts an example wireless device including a mechanism for energy
conservation at access points.
DESCRIPTION OF THE EMBODIMENT(S)
[0039] The description that follows includes exemplary systems, methods, techniques,
instruction sequences, and computer program products that embody techniques of the
present inventive subject matter. However, it is understood that the described
embodiments may be practiced without these specific details. For instance, although
some examples refer to mobile phones that can operate as access points, some
embodiments may include other types of mobile devices that can operate as access points,
or access points that can be powered by either an external power source or batteries. For
instance, well-known instruction instances, protocols, structures, and techniques have not
been shown in detail in order not to obfuscate the description.
[0040] Traditionally, access points have been based on a service model that requires the
access points to always be available to receive transmissions from one or more clients
(e.g., communicating stations). Mobile access points (e.g., mobile phones behaving as
access points) can provide portability and the ability to connect to a communication
network (e.g., Internet) at any time without the need for access to a power source.
However, the access point service model requiring the access point to always be available
and the access point’s limited battery capacity reduces the time that the mobile access
point can be used. Power saving mechanisms can implemented on the mobile access
point by altering the service model that requires the access point to always be available.
In implementing the power saving mechanisms, the access point can be configured to
enter into a low powered state for a predefined period of time based, at least in part, on
sleep intervals associated with the clients connected to the access point. By operating in
a low powered state during predefined intervals, the mobile access point can conserve
power and prolong battery life.
[0041] Figure 1 is an example conceptual diagram illustrating network components
configured to enable energy conservation in an access point. Figure 1 depicts an access
point 102 in communication with a station 112 via a wireless communication network
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116. The access point 102 can be a mobile access point or a mobile phone configured to
act as an access point. The access point 102 comprises a transceiver unit 106, a power
saving unit 108, and processing units 110. The transceiver unit 106 is connected to the
power saving unit 108 and the processing unit 110. The power saving unit 108 is also
connected to the processing unit 110.
[0042] At stage A, the transceiver unit 106 in the access point 102 receives a message
from the station 112 indicating a time interval for which the connected station 112 will be
in sleep mode (“station sleep interval”). The station enters the sleep mode, i.e., a low
powered state, to conserve energy and preserve battery life. The station 112 may be
connected to the access point 102 or may be attempting to connect to the access point
102.
[0043] At stage B, the power saving unit 108 in the access point 102 determines when
and for how long the access point should quiet the communication channel and enter into
a sleep mode. The power saving unit 108 can calculate how long the access point 102
remains in sleep mode based on the station sleep interval (indicated by the station 112 at
stage A). The access point 102 may be connected to a plurality of stations and each
station 112 connected to the access point 102 can be associated with a different station
sleep interval. In other words, each of the plurality of stations can enter the sleep mode at
a different time and remain in the sleep mode for a different period of time. Therefore,
the power saving unit 108 calculates access point quiet information based on when and
for how long each of the connected stations 112 are in sleep mode. The access point
quiet information can indicate a time instant at which the access point 102 enters the
sleep mode, a time instant at which the access point 102 wakes up from the sleep mode, a
time interval for which the access point 102 is in sleep mode (“access point sleep
interval”), etc. In the example of Figure 1, the access point 102 is shown connected to
one station 112. Therefore, the access point 102 can quiet the channel, enter the sleep
mode, wake up from the sleep mode, allow access to the channel, etc. based on the
connected station’s sleep interval. If no stations are connected to the access point 102,
the access point 102 can wake up from the sleep mode every beacon interval, transmit a
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beacon, wait for a response for a preconfigured period of time, and enter the sleep mode
again.
[0044] At stage C, the transceiver unit 106 in the access point 102 transmits a beacon,
or another suitable message, indicating the access point quiet information determined at
stage B. By transmitting the access point quiet information, the access point 102
indicates, to each of the connected stations 112 and other stations that are not connected
to the access point 102, when and for how long the channel will be quieted and the access
point will be in sleep mode. The access point may also use the quiet information to
indicate when the access point 102 wakes up from the sleep mode, exchanges
data/management information, and opens up the communication channel for access. The
access point 102 may also indicate how often the access point enters sleep mode, how
long the access point remains in sleep mode, etc. In one implementation, the access point
102 can indicate when and for how long the access point will be in sleep mode in terms
of a beacon interval time period. For example, the access point 102 can indicate, in the
quiet information, that the access point 102 will enter the sleep mode at the next beacon
interval, wake up after two beacon intervals, remain awake to receive and transmit
information for one beacon interval, and then enter the sleep mode. In another
implementation, the access point 102 can use any suitable time unit (e.g., milliseconds,
etc.) to indicate when and for how long the access point 102 will quiet the
communication channel and enter the sleep mode. The station 112 may use the quiet
information to determine how long the communication channel will be available for
access.
[0045] At stage D, the station 112 receives the transmitted beacon. The station 112
extracts the transmitted access point quiet information from the received beacon. The
station 112 can use the beacon for time synchronization. The station 112 can also use the
access point quiet information to identify when and for how long access to the
communication channel will be blocked.
[0046] At stage E, the station 112 enters the sleep mode. In one implementation, a
power unit (not shown) in the station 112 may determine that the time interval for
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which the station 112 will be in sleep mode has begun. The station 112 may update a
station sleep timer with the station sleep interval. The station may use the station sleep
timer to determine exactly when the station 112 should enter sleep mode. In one
implementation, on determining that the station sleep timer has expired (e.g., counted
down to zero), the power unit may cause the station 112 to enter the sleep mode. The
power unit may direct the station’s transceiver to stop transmitting or receiving signals.
The power unit may also direct one or more other processing units in the station 112 to
switch to a low powered state to conserve energy. Additionally, before the station enters
sleep mode, the station (or the power unit) can update a “station available timer” with the
amount of time that should elapse before the station wakes up from the sleep mode.
[0047] At stage F, the power saving unit 108 in the access point 102 determines that the
access point 102 should quiet the communication channel and enter a sleep mode. As
described with reference to the station 112, in one implementation, the access point 102
can also comprise an access point sleep timer. The power saving unit 108 can monitor
the access point sleep timer and direct the access point 102 to enter the sleep mode when
the access point sleep timer expires. For example, the power saving unit 108 can direct
the transceiver unit 104 and the other processing units 110 in the access point 102 to
switch to a low powered state to conserve battery power. While in the sleep mode, the
access point 102 may not transmit information to or receive information from the stations
112. Thus, by transmitting the access point quiet information in the beacon (at stage B)
to all stations connected to or intending to connect to the access point 102, the access
point 102 ensures that no station 112 transmits information while the access point 102 is
in the sleep mode.
[0048] At stage G, the power saving unit 108 determines that the communication
channel should be opened for access. The power saving unit 108 may comprise a timer
indicating how much time should elapse before the access point wakes up from sleep
mode. When the timer reaches zero, the power saving unit 108 can trigger the access
point 102 (e.g., the transceiver unit 106 and the processing units 110) to wake from the
low powered state. In one implementation, the power unit 108 may use the access point
sleep timer to keep track of 1) how long the access point should remain in sleep
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mode, and 2) when the access point should enter sleep mode. In another implementation,
the power unit 108 may comprise two separate timers, a first timer for determining when
the access point should enter sleep mode (i.e., the access point sleep timer) and a second
timer for determining when the access point should wake up from sleep mode.
[0049] At stage H, the transceiver unit 104 transmits a beacon on the communication
channel. The access point 102 wakes up from sleep mode, opens access to the
communication channel, and transmits a beacon in time for the connected station 112 to
receive the beacon and maintain connectivity with the access point 102. In transmitting
the beacon, the access point 102 can indicate that the communication channel is available
for contention-based access.
[0050] At stage I, the station 112 wakes up from the sleep mode. In one
implementation, on determining that the station available timer has expired (e.g., counted
down to zero), the power unit can cause the station 112 to wake up from the sleep mode.
The station 112 wakes up from sleep mode in time to receive the beacon transmitted by
the access point (at stage H) and maintain connectivity with the access point 102. The
station 112 can also update the station sleep timer to indicate when the station should
enter the sleep mode again. The station 112 can also transmit data and/or management
information (if any) to the access point 102.
[0051] In one implementation, communication between the access point 102 and the
station 112 may be governed by a set of standards, defined by the Institute of Electrical
and Electronics Engineers (IEEE) 802.11 committee, for Wireless Local Area Network
(WLAN) communication. The IEEE 802.11 standards define frame formats for
transmission of data and management information. It is noted, however, that in other
implementations, the communication between the access point 102 and the station 112
may be governed by other existing or future standards (or amendments to current
standards), e.g., 802.16, or by proprietary protocols implemented by the network
components. Figure 2 illustrates example frame formats for transmission of management
information. Figure 2 illustrates frame formats for a beacon frame 200, a quiet
information element (Quiet I.E) 220, and a probe response frame 240 in accordance
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with IEEE 802.11 communication standards. An access point (e.g., the access point 102
of Figure 1) can transmit a beacon frame 200 for time synchronization between one or
more connected stations (e.g. station 112 of Figure 1) and the access point 102. The
access point 102 can also use the beacon frame 200 to transmit the access point quiet
information and to inform stations if they are to receive data frames from the access point
102. The beacon frame comprises a beacon header 202 and a beacon payload 220. The
beacon header 202 comprises control information (e.g., frame number) while the beacon
payload can comprises information about the communication channel (e.g., channel
frequency, a service set identifier, data rates supported on the communication channel,
etc.), a beacon interval (i.e., a time period between transmission of beacon frames), etc.
[0052] Additionally, the beacon payload 204 comprises the quiet information element
(Quiet I.E) 220. The access point 102 can use the Quiet I.E 220 to temporarily quiet the
communication channel and enter sleep mode to prolong battery life. The Quiet I.E 220
comprises a Quiet I.E header 222 and a Quiet I.E payload 224. The Quiet I.E payload
224 comprises a Quiet Count 226, a Quiet Period 228, a Quiet Duration 230, and a Quiet
Offset 232. The Quiet Count 226 indicates a number of target beacon transmission time
(TBTT) until the beacon interval during which the quiet interval begins. In other words,
the Quiet Count 226 indicates when the access point will quiet the communication
channel. The Quiet Period 228 indicates a number of beacon intervals between
consecutive quiet intervals (e.g., how often the access point enters sleep mode). The
Quiet Duration 230 indicates a time period for which the access point quiets the
communication channel and enters sleep mode. The Quiet Offset 232 indicates an offset
(if any) after a beacon interval when the next quiet period will begin (e.g., if the Quiet
Duration does not coincide with the start of a beacon interval).
[0053] Additionally, the access point 102 can also transmit the Quiet I.E 220 as part of
the probe response frame 240. The probe response frame 240 comprises a probe
response header 242 and a probe response payload 244. The access point 102 transmits a
probe response frame 240 in response to a probe request frame from the station scanning
the communication channels for existing networks and access points. The probe response
frame 240 comprises information similar to the beacon frame 200. The probe response
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payload 244 comprises the Quiet I.E 220 along with other information such as channel
frequency, the service set identifier, data rates supported on the communication channel,
etc.
[0054] Figure 3 and Figure 4 depict a flow diagram illustrating example operations for
an access point configuring a quiet interval. Flow 300 begins at block 302 in Figure 3.
[0055] At block 302, a message is received from a station indicating a time interval for
which the station will enter sleep mode (“station sleep interval”). For example, the
station 112 of Figure 1 may indicate, to the access point 102, when and for how long the
station 112 will enter sleep mode. In one implementation, the access point can be mobile
phone acting as an access point. It is noted, however, that in other implementations the
access point can be other types of access points that can operate using either battery
power or an external power source. In one implementation, a station complying with
IEEE 802.11 communication standards may indicate how often the station listens (on the
communication channel) for beacon frames in a Listen Interval in an Association Request
Management Frame. The Listen Interval is typically indicated as a multiple of the
beacon interval. For example, a station with a Listen Interval of 2 will not receive
beacons (i.e., will be in sleep mode) for two beacon intervals. The access point may
receive Association Request Management Frames (or other messages indicating a time
instant and/or the time interval for which the station will be in sleep mode) from one or
more stations connected to or intending to connect to the access point. The flow
continues at block 304.
[0056] At block 304, the message indicating the station sleep interval is analyzed to
determine access point quiet information. For example, the power saving unit 108 in the
access point 102 can analyze the message received (at block 302) to determine the access
point quiet information (e.g., access point sleep interval, when the access point wakes up
from the sleep mode, etc). As described earlier, stations operating in a power save mode
typically go to sleep to conserve power and wakeup only for a predetermined number of
beacon intervals. The access point can use information indicating when and for how long
the station goes to sleep (as indicated, e.g., in the Listen Interval) to determine when
18
and for how long the access point can lock the communication channel and enter a sleep
mode. For example, if a station connected to the access point wakes up every fifth
beacon interval, it may be sufficient for the access point to wakeup just before the start of
the fifth beacon interval and transmit a beacon frame in time for the connected station to
receive the beacon frame. If there are multiple stations connected to the access point, the
access point can calculate a least common factor of the station sleep interval (e.g., the
Listen Interval) associated with each of the connected stations and accordingly determine
when to wake up from sleep mode. For example, if three stations with Listen Intervals 3,
6, and 9 respectively are connected to the access point, then the access point may transmit
a beacon once every three (the least common factor of 3, 6, and 9 is 3) beacon intervals to
ensure that the stations remain connected to the access point. After the access point
determines the access point quiet information, the flow continues at block 306.
[0057] At block 306, a beacon frame comprising the access point quiet information is
generated. For example, the access point 102 may generate the beacon frame. In one
implementation, the beacon frame may be in the format described with reference to
Figure 2 (see beacon frame 200 of Figure 2). The access point may also indicate the
access point quiet information in a probe response frame (e.g., the probe response frame
240 of Figure 2). In another implementation, the access point may notify the stations of
the access point quiet information using other suitable message formats. The flow
continues at block 308.
[0058] At block 308, the beacon frame (generated at block 306) is transmitted on the
communication channel. The beacon frame is transmitted to all the stations listening on
the communication channel. The beacon ensures that stations that are connected to the
access point remain connected to and are in synchronization with the access point. In
transmitting the beacon, the access point can advertise its presence and inform stations
listening on the communication channel of the access point’s capabilities (e.g., access
point identifier, data rates supported, etc). As described earlier, the beacon frame is also
used to transmit the access point quiet information and notify the stations of when and for
how long the communication channel will be quieted. By transmitting the access point
quiet information, the access point can control access to the communication
19
channel during the time the access point is in sleep mode. Thus, the access point can also
control transmissions from the connected stations to the access point. The flow continues
at block 310 in Figure 4 (see connector A).
[0059] At block 310, it is determined whether there exists information to be transmitted
to the connected stations. The access point may access a buffer comprising pending data
frames to be transmitted to determine if there exists data to be transmitted to the
connected stations. In some implementations, the access point may also transmit
management information to connected stations and/or stations that wish to connect to the
access point. For example, the access point may determine that an association response
frame should be transmitted in response to the station transmitting an association request
frame to connect to the access point’s network. If it is determined that there exists
information to be transmitted to the stations, the flow continues at block 320. Otherwise,
the flow continues at block 312.
[0060] At block 320, the information is transmitted to the stations. For example, the
access point 102 may transmit data frames to the connected station 112. In some
implementations, the access point may determine whether there is sufficient time for data
transmission before the stations and the access point enter a sleep mode. In one example,
the access point may access an access point sleep timer and determine the amount of time
remaining until the access point quiets the communication channel and enters the sleep
mode. The access point can calculate the amount of time required for data transmission
based on data rate, frame length, etc. If the access point determines that the stations will
be awake to receive all the data to be transmitted, the access point transmits the data.
Otherwise, the access point can buffer frames destined for the connected stations and
alert the stations (e.g., via a beacon, a traffic indication map (TIM), etc.) when the
stations and the access point wake up from sleep mode. The flow continues at block 312.
[0061] At block 312, it is determined whether a station is transmitting information. The
station (e.g., the station 112) may transmit data or management information to the access
point (e.g., the access point 102). For example, a station connected to the access point
may transmit one or more data frames. As another example, a station connected to the
20
access point may transmit a disassociation frame to the access point to terminate a
connection with the access point. As another example, a station trying to connect to the
access point may transmit a probe request frame to request a connection with the access
point. The stations can transmit data and management information using other suitable
communication protocols. If it is determined that the station is transmitting data, the flow
continues at block 322. Otherwise, the flow continues at block 314.
[0062] At block 322, information is received from the stations. For example, the access
point 102 of may receive data and/or management information from the station 112. The
flow continues at block 314.
[0063] At block 314, it is determined whether the access point should enter the sleep
mode. For example, the power saving unit 108 in the access point 102 may determine
that the access point should enter the sleep mode. As described earlier, the access point
may comprise an access point sleep timer indicating the amount of time that should
elapse before the access point quiets the communication channel and enters sleep mode.
The power saving unit 108 may trigger one or more operating units (e.g., a transceiver
unit, etc.) in the access point to enter the sleep mode when the value of the access point
sleep timer reaches zero. If it determined that the access point should enter sleep mode,
the flow continues at block 316. Otherwise, the flow continues at block 310, where the
access point determines whether there is data to be transmitted to or data to be received
from a station.
[0064] At block 316, the access point enters the sleep mode. For example, the power
saving unit 108 in the access point 102 may direct the transceiver unit 106 and other
processing units 110 in the access point 102 to switch to a low powered state to conserve
battery power. Before the access point enters the sleep mode, the access point also quiets
the communication channel (i.e., locks access to the communication channel). By
locking the communication channel before entering sleep mode, the access point ensures
that stations do not transmit data or management frames to the access point when the
access point is in sleep mode. A timer may also be updated to indicate the time (e.g.,
Quiet Duration 230 of Figure 2) that should elapse before the access point
21
wakes up from sleep mode. From block 416, the flow ends.
[0065] After the access point wakes up from sleep mode, the access point opens the
communication channel for contention-based access and transmits the beacon. The
access point also transmits data and/or management frames that it has for the connected
stations and remains awake for a predetermined time interval to receive any data and/or
management frames from the connected stations or stations that wish to connect to the
access point. The access point then locks access to the communication channel and
enters the sleep mode again.
[0066] The various time intervals associated with the access point configured for
energy conservation are further described using timing diagrams 5A and 5B. Figure 5A
is a timing diagram 500 illustrating transmission operations when no stations are
connected to the access point. Time interval 502 indicates the interval during which the
access point (e.g., access point 102) is awake. Stations (e.g., station 112) can
communicate with the access point during the interval 502. For example, a station may
detect a beacon transmitted by the access point during the time interval 502 and transmit
a probe request frame to request a connection to the access point. Time interval 504
indicates an interval during which the access point is in sleep mode. The sleep mode is a
low power state, which the access point enters to conserve energy and enhance battery
life. The access point transmits a Quiet Information Element (Quiet I.E) in the beacons
or probe response frames (transmitted in response to the probe request frames) during
time interval 502 (i.e., before the access point enters sleep mode). The access point uses
the Quiet I.E to indicate when and for how long the access point will be in sleep mode
(i.e., the time interval 504). In other words, the access point locks the communication
channel for the interval indicated by the time interval 504 and does not receive
communications from or transmit communications to other stations.
[0067] Arrowhead 510 indicates a time instant at which the access point wakes up (e.g.,
just before a predetermined target beacon transmission time (TBTT)) to transmit the
beacon. Arrowhead 512 indicates a time instant at which the Quiet Offset (as indicated in
the Quiet I.E.) begins and the access point enters the sleep mode. Thus, the quiet time
22
interval 504 repeats every beacon interval 508. Because the access point is not connected
to any station, the access point wakes up every beacon interval 508 (which is the sum of
time intervals 502 and 504) to transmit the beacon as depicted by arrowheads 510 and
514. Likewise, the access point enters sleep mode every beacon interval (see arrowheads
512 and 516).
[0068] In one implementation, the access point configures the Quiet I.E frame (see
Quiet I.E frame format 220 in Figure 2) by assigning a Quiet Count 518 of 1 beacon
interval and a Quiet Period of 1 indicating that the quiet period starts at the next TBTT
(denoted by arrowhead 510) and that the quiet period repeats every beacon interval. The
access point can also configure the quiet duration to time interval 504 indicating that the
communication channel should be quiet for the time period indicated by time interval
504. Likewise, the access point can configure the quiet offset to time interval 502
indicating that the quiet period starts after time interval 502.
[0069] Figure 5B is a timing diagram 550 illustrating transmission operations for an
access point connected to a station. In one example, the connected station (e.g., the
station 112) is connected to the access point (e.g., the access point 102) with a Listen
Interval (indicated in an Association Request Management Frame) of two beacon
intervals. The connected station uses the Listen Interval to indicate to the access point
that the station will wake up every second beacon interval to listen for beacons (for
synchronization) from and exchange data and/or management information with the access
point.
[0070] Time interval 552 indicates the interval during which the access point is awake.
The access point and the connected station can exchange data and management frames
during this interval. For example, the connected station may transmit a data frame to the
access point. As another example, the access point can indicate to a station (e.g., by
transmitting a Traffic Indication Map (TIM)) if the access point has data/management
frames for the station. New stations (stations that are not connected to the access point)
can also communicate with the access point during the interval 552. For example, a
station may detect a beacon transmitted by the access point during the time interval
23
552 and transmit a probe request frame to request a connection to the access point. Time
interval 554 indicates an interval during which the access point is in sleep mode.
[0071] With reference to the Quiet I.E. frame structure 220 depicted in Figure 2, the
access point can configure the Quiet I.E frame based on the station’s Listen Interval (two
beacon intervals). The access point can configure the Quiet I.E with a Quiet Count 570
of 1 beacon interval and a Quiet Period 572 of 2 beacon intervals indicating that the quiet
period starts at the next TBTT (see arrowhead 560) and that the quiet period repeats
every second beacon interval (see arrowhead 564). The access point can also configure
the Quiet Duration to time interval 554 indicating that the communication channel should
be quiet for the time period indicated by time interval 554. Likewise, the access point
can configure the Quiet Offset to time interval 552 indicating that the quiet period starts
after time interval 552.
[0072] Arrowhead 560 indicates a time instant at which the access point wakes up (e.g.,
just before the TBTT) to transmit the beacon. Arrowhead 562 indicates a time instant at
which the Quiet Offset (as indicated in the Quiet I.E.) begins and the access point enters
the sleep mode. As depicted by arrowheads 560 and 564, the access point wakes up
every second beacon interval 558 to transmit beacons, probe responses, data frames, etc.
Also, as depicted by arrowheads 562 and 566, the quiet duration 554 repeats every
second beacon interval 558.
[0073] It should be noted that the time intervals during which the access point is awake
and in sleep mode and the beacon interval are configurable. The user can configure any
one or all of the time intervals depending on the type and nature of the traffic that is
estimated to pass through the access point. Additionally, the user may also configure the
access point to dynamically configure the time intervals that the access point is awake
and in sleep mode based on the traffic handled by the access point.
[0074] Figure 6 and Figure 7 depict a flow diagram illustrating example operations for a
station connected to an access point. Flow 600 begins at block 602 in Figure 6.
[0075] At block 602, a time interval for which the station will be in sleep mode is
24
provided to an access point. For example, the station 112 may send a message indicating
to the access point 102 a number of beacon intervals it intends to spend in sleep mode. In
one implementation, the station can indicate a station sleep interval (i.e., the number of
intervals the station will be in sleep mode) by configuring a Listen interval in an
Association Request Management frame. In some implementations, the station sleep
interval may not be described as multiples of the beacon interval. Instead, the station
may use any suitable unit of time (e.g., seconds, milliseconds, etc.) to indicate the station
sleep interval and a time interval at which the station sleep interval repeats (if applicable).
Also, the station may use any suitable message format and/or frame format (agreed upon
by the access point and the station) to communicate with the access point. The flow
continues at block 604.
[0076] At block 604, a beacon comprising access point quiet information is received
from the access point. For example, the station 112 receives a beacon (e.g., the beacon
frame 200 of Figure 2) from the access point 102. As described in Figure 3 (see
discussion for blocks 302 and 304), in one implementation, the access point can receive
Association Request Management frames indicating Listen Intervals from a plurality of
connected stations. The access point can calculate an access point quiet interval from the
received Listen Intervals and transmit the access point quiet interval as part of the quiet
information in a beacon frame. During the access point quiet interval, the access point
can enter the sleep mode and block access to the communication channel. The flow
continues at block 606.
[0077] At block 606, the access point quiet information is retrieved from the beacon
received at block 604. For example, the station 102 may process the received beacon to
extract the access point quiet information. In one implementation, the station may extract
the quiet information element (e.g., the Quiet I.E 220 of Figure 2) from the beacon to
determine when the quiet duration starts, the length of the quiet duration, when data and
management information can be transmitted, etc. The stations can also update a Network
Allocation Vector (NAV) timer with the Quiet Duration (i.e., the Quiet duration 230 of
Figure 2) indicated in the Quiet Information Element. The NAV timers count down so
that the stations wake up in time to receive the beacon transmitted by the access point.
25
In another implementation, the station may retrieve the access point sleep interval from
the access point quiet information (transmitted using any suitable message format and
communication protocol) and accordingly update a station available timer. The flow
continues at block 608.
[0078] At block 608, it is determined whether the communication medium is available.
For example, for contention-based communication channel access, the station 112 may
transmit a request-to-send (RTS) frame on the communication channel to the access point
102 to determine if the communication medium is available. The station may also
indicate an amount of time for which the communication channel will be in use. The
access point may transmit a clear-to-send (CTS) signal to one of the stations contending
for the communication channel to indicate that the communication channel is available
for transmission. Other stations may also receive the RTS/CTS signal and refrain from
accessing the communication channel during the time interval when another station is
transmitting. If it is determined that the communication medium is available for data
transmission, the flow continues at block 610. Otherwise, the flow continues at block
611.
[0079] At block 611, on determining that the communication medium is not available
for transmission, the station waits for a specified period of time. In the contention-based
channel access example described with reference to block 608, other stations that do not
receive permission to transmit along the communication channel also receive the
RTS/CTS frames. The stations can update a timer and wait until the transmitting station
has released the communication channel. In one implementation, the station may wait for
a random amount of time before it senses the communication channel to avoid frame
collision. In another implementation, the station waits for the period of time specified in
an RTS frame transmitted by a station that is currently transmitting. The flow continues
at block 608, where, after the specified period of time, the station senses the
communication channel to determine whether the communication channel is available.
[0080] At block 610, a time period required to transmit information (“transmission
time”) to the access point is calculated. For example, the station 112 may calculate
26
the time period required for transmission of a data/management frame to the access point
102. The transmission time may be calculated based on a number of bytes of data to be
transmitted, frame size, the capacity and data rate of the communication channel, the
network traffic, a network model, etc. The flow continues at block 612 in Figure 7.
[0081] At block 612, it is determined whether the transmission time is greater than the
time to the start of the station sleep interval. In other words, it is determined whether
there is sufficient time to transmit information to the access point before the station enters
a sleep mode. For example, the transmission time may be compared with an amount of
time indicated by a station sleep timer. Stations that are not connected to the access point
may determine whether the transmission time is greater than the time that should elapse
before the access point locks the communication channel and enters a sleep mode. If it is
determined that the time required for data transmission is greater than the time before the
stations enters the sleep mode, the flow continues at block 624. Otherwise, the flow
continues at block 614.
[0082] At block 624, the data is transmitted to the access point. The station connected
to the access point transmits information in response to the station determining that the
transmission time is less than the amount of time that should elapse before the station
enters sleep mode. A station that is not connected to the access point transmit
information to the access point in response to the station determining that the
transmission time is less than the amount of time that should elapse before the access
point quiets the communication channel. The station can transmit a data frame or a
management frame to the access point. For example, a station may transmit a Probe
Request Frame to scan for an existing and compatible access point, a data frame to
transmit data to a second station via the access point, etc.
[0083] At block 614, information is prevented from being transmitted to the access
point. The flow 600 moves from block 612 to block 614 if it is determined that the
transmission time is greater than the time before the station enters the sleep mode. For
example, the station 112 prevents the transmission of data and/or management
information to the access point 102 in response to the station determining that the
27
transmission time is greater than the time before the station enters the sleep mode. The
information to be transmitted may be stored (e.g., in a buffer frame) and may be
transmitted when the station wakes up from the sleep mode. In another implementation,
stations that are not connected to the access point may store information to be transmitted
and may transmit the information (e.g., management frames requesting connectivity)
when the access point wakes up from the sleep mode and opens access to the
communication channel. After the station determines whether it should transmit
information (see block 624) or prevent transmission of the information (see block 614),
the flow continues at block 616.
[0084] At block 616, it is determined whether the station should enter sleep mode. As
described earlier, the stations may update a local timer with the amount of time that
should elapse before the station enters sleep mode. In one implementation, the station
sleep timer may count down, triggering the station to enter sleep mode when the counter
reaches zero. If it is determined that the station should enter sleep mode, the flow
continues at block 626. Otherwise, the flow continues at block 622.
[0085] At block 622, it is determined whether there is any information to be
transmitted. For example, the station 122 may determine whether there exist any data
and/or management frames to be transmitted to the access point 102. If the station
determines that there exists information that should be transmitted to the access point, the
flow continues at block 608 in Figure 6 where the station determines whether the
communication channel is available. Otherwise, the flow continues at block 616 where
the station determines whether it should enter sleep mode.
[0086] At block 626, the station enters sleep mode. As described earlier, the stations
may update a station available timer with the amount of time that the communication
channel is quieted and the access point is in the sleep mode, as indicated by the access
point. In one implementation, the station 112 may update its NAV timer with the Quiet
Duration 230 indicated in the Quiet I.E 220 of Figure 2. As the stations are in the sleep
mode, the NAV timer counts down triggering the stations to wake up when the NAV
timer reaches zero. In some implementations, the stations may use any
28
suitable counter/ timer to indicate when stations can enter or wake up from the sleep
mode. From block 626, the flow ends.
[0087] It should be understood that the depicted flow diagrams (Figures 3, 4, 6, and 7)
and the timing diagram (Figure 5) are examples meant to aid in understanding
embodiments and should not be used to limit embodiments or limit scope of the claims.
Embodiments may perform additional operations, fewer operations, operations in a
different order, operations in parallel, and some operations differently. For example,
Figure 7 describes the station determining whether there is sufficient time for
transmission before the communication channel is quieted (see block 612). However, in
some implementations, the onus to determine whether the station should be allowed to
transmit may be on the access point. For example, the station may transmit an RTS
signal to the access point indicating the frame length, transmission time, etc. The access
point may determine that the transmission time is greater than the time before the access
point quiets the communication channel. The access point may prevent the station from
transmitting information.
[0088] Also, because the access point is awake and can transmit/receive data and/or
management information for only a predefined period of time, there may be a trade-off
between the access point’s performance and power saving for prolonged battery life. In
some implementations, the access point can be configured to operate in full power mode
when one or more stations are connected to the access point. The access point may enter
into power saving mode (i.e., sleep mode) and wake up for a limited time interval when
there are no stations connected to the access point.
[0089] As described above, in some embodiments, the access point is configured to
quiet the communication medium (i.e., the communication channel) by transmitting a
quiet information element (Quiet I.E.) in the beacon frame and/or a probe response frame.
However, in some implementations, the access point and/or one or more of the connected
stations may not support receiving the Quiet I.E. In some implementations, the access
point can quiet the communication channel using a CTS (Clear-to-Send) to self scheme.
The CTS-to-self scheme is a generic scheme that is recognized by all clients (e.g.,
connected stations, transmitting stations, mobile phones, access points, etc.)
29
implementing IEEE 802.11 communication standards. A CTS signal indicates a duration
for which a station is allowed to transmit data on the communication channel. The CTS
signal also indicates, to other stations, the duration for which the communication channel
will be busy and therefore, should not be accessed. The access point can transmit a CTS
signal to itself indicating a time interval for which the communication channel will be
locked (e.g., the Quiet Duration, the access point sleep interval, etc). The CTS signal,
which is also received by other stations, indicates the other stations should not access the
communication channel for the indicated time interval. The access point can enter the
sleep mode on transmitting the CTS signal. This can ensure that no station transmits data
or management frames to the access point while the access point is in the sleep mode.
This also ensures that no data or management information is lost while the access point is
in sleep mode.
[0090] Embodiments may take the form of an entirely hardware embodiment, an
entirely software embodiment (including firmware, resident software, micro-code, etc.)
or an embodiment combining software and hardware aspects that may all generally be
referred to herein as a “circuit,” “module” or “system”. Furthermore, embodiments of the
inventive subject matter may take the form of a computer program product embodied in
any tangible medium of expression having computer usable program code embodied in
the medium. The described embodiments may be provided as a computer program
product, or software, that may include a machine-readable medium having stored thereon
instructions, which may be used to program a computer system (or other electronic
device(s)) to perform a process according to embodiments, whether presently described
or not, since every conceivable variation is not enumerated herein. A machine-readable
medium includes any mechanism for storing or transmitting information in a form (e.g.,
software, processing application) readable by a machine (e.g., a computer). The
machine-readable medium may include, but is not limited to, magnetic storage medium
(e.g., floppy diskette); optical storage medium (e.g., CD-ROM); magneto-optical storage
medium; read only memory (ROM); random access memory (RAM); erasable
programmable memory (e.g., EPROM and EEPROM); flash memory; or other types of
medium suitable for storing electronic instructions. In addition, embodiments
30
may be embodied in an electrical, optical, acoustical or other form of propagated signal
(e.g., carrier waves, infrared signals, digital signals, etc.), or wireline, wireless, or other
communications medium.
[0091] Computer program code for carrying out operations of the embodiments may be
written in any combination of one or more programming languages, including an object
oriented programming language such as Java, Smalltalk, C++ or the like and
conventional procedural programming languages, such as the "C" programming language
or similar programming languages. The program code may execute entirely on a user's
computer, partly on the user's computer, as a stand-alone software package, partly on the
user’s computer and partly on a remote computer or entirely on the remote computer or
server. In the latter scenario, the remote computer may be connected to the user’s
computer through any type of network, including a local area network (LAN), a personal
area network (PAN), or a wide area network (WAN), or the connection may be made to
an external computer (for example, through the Internet using an Internet Service
Provider).
[0092] Figure 8 depicts an example wireless device e.g., WLAN device 800. In one
implementation, the WLAN device 800 may be a WLAN station (e.g., station 112 of
Figure 1). In another implementation, the WLAN device 800 may be an access point
operating in an 802.11 WLAN communication environment (e.g., access point 102 of
Figure 1). The WLAN device 800 includes a processor unit 802 (possibly including
multiple processors, multiple cores, multiple nodes, and/or implementing multi-threading,
etc.). The WLAN device 800 includes a memory unit 806. The memory unit 806 may be
system memory (e.g., one or more of cache, SRAM, DRAM, zero capacitor RAM, Twin
Transistor RAM, eDRAM, EDO RAM, DDR RAM, EEPROM, NRAM, RRAM,
SONOS, PRAM, etc.) or any one or more of the above already described possible
realizations of machine-readable media. The WLAN device 800 also includes a bus 810
(e.g., PCI, ISA, PCI-Express, HyperTransport®, InfiniBand®, NuBus, etc.), and network
interfaces 804 that include at least one wireless network interface (e.g., a WLAN
interface, a Bluetooth® interface, a WiMAX interface, a ZigBee® interface, a Wireless
USB interface, etc.). The WLAN device 800 also includes a power saving unit 808.
31
The power saving unit 808 comprises functionality for conserving power to prolong
battery life in an access point described in accordance with Figures 1-7.
[0093] Any one of the above-described functionalities may be partially (or entirely)
implemented in hardware and/or on the processing unit 802. For example, the
functionality may be implemented with an application specific integrated circuit, in logic
implemented in the processing unit 802, in a co-processor on a peripheral device or card,
etc. Further, realizations may include fewer or additional components not illustrated in
Figure 8 (e.g., additional network interfaces, peripheral devices, etc.). The processor unit
802 and the network interfaces 804 are coupled to the bus 810. Although illustrated as
being coupled to the bus 810, the memory 806 may be coupled to the processor unit 802.
[0094] While the embodiments are described with reference to various implementations
and exploitations, it will be understood that these embodiments are illustrative and that
the scope of the inventive subject matter is not limited to them. In general, the dynamic
energy saving mechanism for access points as described herein may be implemented with
facilities consistent with any hardware system or hardware systems. Many variations,
modifications, additions, and improvements are possible.
[0095] Plural instances may be provided for components, operations, or structures
described herein as a single instance. Finally, boundaries between various components,
operations, and data stores are somewhat arbitrary, and particular operations are
illustrated in the context of specific illustrative configurations. Other allocations of
functionality are envisioned and may fall within the scope of the inventive subject matter.
In general, structures and functionality presented as separate components in the
exemplary configurations may be implemented as a combined structure or component.
Similarly, structures and functionality presented as a single component may be
implemented as separate components. These and other variations, modifications,
additions, and improvements may fall within the scope of the inventive subject matter.
Dated this 5th day of May, 2009
G. DEEPAK SRINIWAS
OF K & S PARTNERS
AGENT FOR THE APPLICANTS
32

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=KC3CSLDiuxGMAWETOTJtuQ==&loc=vsnutRQWHdTHa1EUofPtPQ==


Patent Number 272830
Indian Patent Application Number 1177/MUM/2009
PG Journal Number 18/2016
Publication Date 29-Apr-2016
Grant Date 28-Apr-2016
Date of Filing 05-May-2009
Name of Patentee QUALCOMM INCORPORATED
Applicant Address 5775 Morehouse Drive San Diego California 92121-1714 United States of America
Inventors:
# Inventor's Name Inventor's Address
1 Badri Srinivasan Sampathkumar #71/B Sri Krishna Apts. 7th Ave. Ashok Nagar Chennai India
PCT International Classification Number H04B17/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA