HK1170092A - Method and system for no buffered traffic indication for wireless local area network (wlan) power save - Google Patents

Description

Method and system for unbuffered traffic indication for Wireless Local Area Network (WLAN) power saving

CROSS-REFERENCE TO RELATED APPLICATIONS/REFERENCES

Priority and benefit of U.S. provisional patent application, serial No.61/244,896, filed on even 23/9/2009, which is hereby incorporated by reference in its entirety.

Technical Field

The present invention relates to communication networks. More particularly, the present invention relates to a method and system for unbuffered traffic indication for WLAN power saving.

Background

IEEE 802.11 describes a communication framework that may enable computing devices to communicate over a Wireless Local Area Network (WLAN). One of the building blocks of a WLAN is the Basic Service Set (BSS). A BSS may include an Access Point (AP) and a plurality of computing devices, or Stations (STAs), that may communicate wirelessly within a coverage area over one or more RF channels. The extent of the coverage area may be determined based on the distance over which the source SAT may transmit data over the RF channel, which may be received by the target STA.

Within the BSS, STAs can operate in two power management modes: an Active Mode (AM) and/or a Power Saving (PS) mode. When the STA is operating in AM, the STA may be fully powered (e.g., within the capacity of the power supply) and may transmit and/or receive data. When the STA operates in PS mode, the STA may operate in an active state during which the STA may transmit and/or receive data, or the STA may enter a sleep state during which it operates with lower (when compared to AM) power consumption and may disable the ability to transmit and/or receive data. When a given STA is in a PS mode sleep state, the given STA may generate data to be transmitted to another STA. While the given STA is in the PS mode sleep state, the given STA may store, or buffer, data. Upon subsequent exit from the PS mode sleep state and entry into the active state, the given STA may send buffered data to other STAs.

Further limitations and disadvantages of conventional (or traditional) techniques will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.

Disclosure of Invention

A method and/or system for bufferless traffic indication (no buffered traffic indication) for Wireless Local Area Network (WLAN) power savings, as set forth more completely in the claims and/or as described in connection with the at least one figure.

Various advantages, aspects and novel features of the invention, as well as details of an illustrated embodiment thereof, will be more fully described with reference to the following description and drawings. Examples

Drawings

Fig. 1 is a block diagram of an exemplary system for enabling bufferless traffic indication for WLAN power save mode based on direct data communication between Stations (STAs) in a Wireless Local Area Network (WLAN) Basic Service Set (BSS) in accordance with an embodiment of the present invention;

FIG. 2A is a diagram of an exemplary quality of service (QoS) capability Information Element (IE) format, according to an embodiment of the present invention;

fig. 2B is a diagram of an exemplary QoS information field format, according to an embodiment of the present invention;

fig. 3A is a diagram of an exemplary WLAN Medium Access Control (MAC) frame format, according to an embodiment of the present invention;

FIG. 3B is a diagram of an exemplary WLAN QoS null frame format, according to an embodiment of the present invention;

fig. 3C is a diagram of an exemplary QoS control field format according to an embodiment of the present invention;

FIG. 4A is a diagram of an exemplary Acknowledgement (ACK) frame format according to an embodiment of the invention;

FIG. 4B is a diagram of an exemplary frame control field format, according to an embodiment of the present invention;

fig. 5A is a diagram of an exemplary power state of a STA transmitting a QoS null frame according to an embodiment of the present invention;

fig. 5B is a diagram of an exemplary power state of an STA transmitting an ACK frame according to an embodiment of the present invention;

fig. 6 is a flowchart of exemplary steps for determining a power state of an STA transmitting a QoS null frame, according to an embodiment of the present invention;

fig. 7 is a flowchart of exemplary steps for determining a power state of an STA receiving a QoS null frame, according to an embodiment of the present invention.

Detailed Description

Certain embodiments of the invention may relate to a method and system for unbuffered traffic indication for Wireless Local Area Network (WLAN) power savings. Various embodiments of the present invention include methods and systems that may be practiced in a network including a coordinating communication device (coordinating communication device) and a plurality of peer communication devices (peer communication devices) that establish peers within the network by each communicating registration information with the coordinating communication device. Each of the associated peer communications devices may enter an active operational state that enables the peer communications devices to transmit and/or receive data over the communications medium. Upon entering the active operating state, the peer communication devices communicate to determine whether any of the peer communication devices has data to send to one or more remaining peer communication devices. If the given peer communication device determines that it does not have data to send to any of the remaining peer communication devices, and that none of the remaining peer communication devices have data to send to it, then the given peer communication device may exit the active operating state and enter a low power operating state that may disable the given peer communication device from sending data and/or receiving data from any of the remaining peer communication devices.

In various embodiments of the invention, one or more peer communication devices within a network may exit a low power operating state and enter an active operating state at the beginning of a negotiated wake window duration. The negotiated awake window duration may include a maximum duration during which the peer communication device continues to remain in an active operating state to listen for messages from other devices indicating a request for further communication. During the negotiation of the awake window duration, each peer communication device may individually determine whether it has stored data to be transmitted to one or more remaining peer communication devices within the network. If the given peer communication device determines that there is data to send to one or more remaining peer communication devices, the given peer communication device may send data to the one or more remaining peer communication devices during the negotiation of the awake window duration. If the given peer communications device determines that there is no data to send to any of the remaining peer communications devices, the given peer communications device may send a no data indication message to each of the one or more remaining peer communications devices.

Each of the remaining peer communication devices that received the no data indication message from the given peer communication device may each determine whether there is any data to send to the given peer communication device that sent the no data indication message. If the remaining peer communications devices determine that there is no data to send to the given peer communications device, the remaining peer communications devices may send a no data acknowledgement message to the given peer communications device, the no data acknowledgement message including an indication that the remaining peer communications devices have no data to send to the given peer communications device. If the remaining peer communications devices determine that there is data to send to the given peer communications device, the remaining peer communications devices may send a no data acknowledgement message to the given peer communications device, the no data acknowledgement message including an indication that the remaining peer communications devices have data to send to the given peer communications device.

Based on the received no-data acknowledgement message, the given peer-to-peer communication may determine whether one or more remaining peer-to-peer communication devices have data to send to the given peer-to-peer communication device. The given peer communication device may enter a low power operating state if the given peer communication device determines that none of the remaining peer communication devices have data to send to the given peer communication device. If the given peer communications device determines that one or more remaining peer communications devices have data to send to the given peer communications device, the given peer communications device may remain in an active operational state beyond the end of the negotiated awake window duration to receive further expected messages from the one or more remaining peer communications devices. If the given peer communication device is in the active operating state until at least the end of the awake window duration is negotiated, the given peer communication device may exit the active operating state and enter a low power operating state after the end of the awake window duration is negotiated.

If the given peer to peer communications device determines that it does not have data to send to any of the remaining peer to peer communications devices and receives a no data indication message from each of the remaining peer to peer communications devices, the given peer to peer communications device may send a no data acknowledgement message in response to each received no data indication message. Each transmitted no-data acknowledgement message may include an indication that the given peer communication device has no data to transmit to the remaining peer communication devices that are recipients of the no-data acknowledgement message. After sending the no data acknowledgement message to each remaining peer communication device, the given peer communication device may enter a low power operating state.

If the given peer communications device determines that it has data to send to one or more of the remaining peer communications devices and receives a no data indication message from one or more of the remaining peer communications devices, the given peer communications device may send a no data acknowledgement message in response to each received no data indication message. Each transmitted no-data acknowledgement message may include an indication that the given peer communication device has data to transmit to the remaining peer communication devices that are recipients of the no-data acknowledgement message. After sending the no data acknowledgement message to one or more remaining peer communication devices, the given peer communication device may remain in an active operating state at least until the end of the negotiated awake window duration.

In an exemplary embodiment of the invention, the network is a WLAN Basic Service Set (BSS), the coordinating communication device is an Access Point (AP), and the peer communication device is a WLAN station device (STA). In an exemplary embodiment of the present invention, the registration information communicated by each STA may include an association (or re-association) message of the AP, where the association (or re-association) message is a request for the STA to associate with the AP. The association (or re-association) message may be referred to as a registration request. The AP may respond to the registration request from the given STA by establishing an association with the given STA. The association may be identified by an Association Identifier (AID). Each AID may be associated with a BSS, where the BSS may be identified by a BSS identifier (BSSID). A STA that has been connected to the BSS in this manner may establish a peer relationship with another STA within the BSS. Peer STAs, which refer to STAs that have established a peer relationship, can then communicate with each other directly and/or using the AP.

In an exemplary embodiment of the present invention, the no data indication message may include a QoS null frame. An exemplary no data indication acknowledgement message may include an Acknowledgement (ACK) frame. Exemplary Power Saving (PS) modes include a sleep state and an active state. The PS mode sleep state may be referred to as a sleep state, and the PS mode active state may be referred to as an active state.

Fig. 1 is a block diagram of an exemplary system for unbuffered traffic indication for initiating a WLAN power save mode based on direct data communication between Stations (STAs) in a Wireless Local Area Network (WLAN) Basic Service Set (BSS), according to an embodiment of the present invention. Referring to fig. 1, a BSS 112 is shown, the BSS including an AP122 and a plurality of STAs: STA _ 1124, and STA _ 2126. STA124 and AP122 may communicate over a Radio Frequency (RF) channel 132. STA126 and AP122 may communicate over RF channel 134. STA124 and STA126 may communicate over RF channel 136. The RF channels 132, 134, and/or 136 may enable transmission and/or reception of signals over a communication medium. In various embodiments of the present invention, communication media may include wireless and/or wired communication media. AP122, STA124, and STA126 may comprise suitable logic, circuitry, and/or code that may enable AP122, STA124, and/or STA126 to perform the operations and/or functions described herein.

STA124 and STA126 may be peer-to-peer communication devices within BSS 112. AP122 may be a coordinating communication device within BSS 112. STA124 may establish an association with AP122 by communicating an association (or re-management) message to AP 122. Messages may also be referred to as frames. Association with AP122 may cause STA124 to connect with BSS 112. Similarly, STA126 may establish an association with AP122 by communicating an association (or re-association) message to AP 122. Association with AP122 may enable STA126 to connect with BSS 112. STA124 and STA126 may establish a direct communication link using setup messages sent through AP 122. AP122 may or may not be aware of the direct link established between STA124 and STA 126.

For PS mode operation of the direct link, a negotiated awake window duration may be established between STA124 and STA 126.

For PS mode operation of the direct link, a wakeup interval duration may be established between STA124 and STA 126. The awake interval duration may include a duration that begins with the start of the negotiated awake window duration, and the start of a subsequent negotiated awake window duration. The negotiated sleep duration may include a duration that begins with the end of the negotiated awake window duration and terminates with the beginning of a subsequent negotiated awake window duration. In various embodiments of the invention, negotiating a sleep duration may include a minimum duration during which the peer communications device continues to remain in the sleep state. The sum of the negotiated awake window duration and the negotiated sleep duration may be equal to the awake interval duration.

Peer STAs, i.e., STA124 and STA126, may establish an RF channel 136. In an exemplary embodiment of the invention, STA124 may communicate a Tunneled Direct Link Service (TDLS) setup message with AP122 over RF channel 132. In response to the TDLS setup message received over RF channel 132, AP122 may communicate the TDLS setup message with STA126 over RF channel 134. In the TDLS setup message communicated over the RF channel 134, the STA126 may receive an indication that the STA124 has requested the establishment of the RF channel 136 to enable direct data communication between the STA124 and the STA 126. STA126 may transmit a response message to AP122 over RF channel 134 in response to the TDLS setup message communicated over RF channel 134. In response to the response message received by AP122 over RF channel 134, AP122 may communicate the response message with STA124 over RF channel 132. In response to the response message received by STA124 over RF channel 132, STA124 and STA126 may establish RF channel 136 to enable direct data communication between STA124 and STA 136. In an exemplary embodiment of the present invention, the response message includes a TDLS response message. Various embodiments of the invention may be practiced when various methods are used to enable direct communication between peer communication devices, such as STAs 124 and 126 that have established a TDLS link, or peer devices in other deployment topologies (e.g., in a mesh network).

Various embodiments of the invention may include methods and systems by which peer communication devices STA124 and STA126 may determine an actual awake window duration based on whether the peer communication devices have data exchanged over a direct data communication link (e.g., RF channel 136). Upon negotiating the start of the awake window duration, STA124 and STA126 may each exit the sleep state and enter the active state. STA124 and STA126 may determine whether there is data exchanged over RF channel 136 during the beginning portion of the negotiated awake window duration. If STA124 determines that there is no data to send to STA126, STA124 may send a QoS null frame to STA126 over RF channel 136. If STA124 determines that there is data to send to STA126, STA124 may send the data to STA126 over RF channel 136.

If STA126 receives the QoS null frame from STA124, STA126 may determine whether it has data to send to STA 124. If STA126 determines that it has data to send to STA124, STA126 may send an ACK frame to STA124 over RF channel 136. The ACK frame may include an indication that STA126 has data to send to STA 124. Upon receiving the ACK frame, STA124 may remain in the active state at least until the end of the negotiated awake window duration. STA126 may then transmit data to STA124 over RF channel 136. The STA126 may remain in the active state at least until the end of the negotiated awake window duration.

If STA126 determines that it has no data to send to STA126, STA126 may send an ACK frame to STA124 over RF channel 136 after receiving the QoS null frame from STA 124. The ACK frame may include an indication that STA126 has no data to send to STA 124. After sending the ACK frame, the STA126 may exit the active state and enter the sleep state. After receiving the ACK frame, STA124 may exit the active state and enter the sleep state. The duration from the beginning of the negotiated awake window duration to the time at which STA124 and/or STA126 exit the active state and enter the sleep state includes a duration referred to as the actual awake window duration. In various embodiments of the invention, the actual awake window duration may comprise a shorter duration than the negotiated awake window duration. Accordingly, the actual sleep duration may comprise a longer duration than the negotiated sleep duration. In various embodiments of the present invention, the sum of the actual awake window duration and the actual sleep duration may be equal to the awake interval duration.

Various embodiments of the present invention enable peer communication devices (e.g., STA124 and STA 126) to reduce power consumption by performing an early exit from an active state when the peer communication devices determine that there is no data exchange between the peer communication devices. In some conventional WLAN systems, STA124 and STA126 may remain in the active state for the duration of the negotiated awake window, regardless of whether STA124 and STA126 have any data to exchange.

In accordance with embodiments of the present invention, the STA124 may communicate with the STA126 that it is capable of engaging in direct data communications with the STA126 to determine when to enter the sleep state. Fig. 2A is a diagram of an exemplary quality of service (QoS) capability Information Element (IE) format according to an embodiment of the present invention. Referring to fig. 2A, a QoS IE 202 is shown. In various embodiments of the invention, STA124 may utilize QoS capabilities IE 202 to communicate its ability to determine when to enter a sleep state based on communications with STA 126. The QoS capabilities IE 202 may include an element id (element id) field 204, a length field 206, and a QoS information field 208. Exemplary meta-ID 204, length 206, and QoS information 208 fields are generally described in one or more IEEE 802.11 standards and/or draft standard documents. In an exemplary embodiment of the invention, the meta-ID 204, length 206, and QoS information 208 fields may each include a plurality of bits forming an octet. In various embodiments of the invention, STA124 may utilize QoS capabilities IE 202 to communicate its ability to determine when to enter a sleep state based on communications with STA 126. In various embodiments of the invention, the QoS information field 208 may include an indicator value that may be set by the STA124 to a value that indicates its ability to determine when to enter a sleep state based on communications with the STA 126. After setting the indicator value in the QoS information field 208, the STA124 may send a plurality of frames, each of which may include the QoS capabilities IE 202. Exemplary frames that may include the QoS capability IE 202 include a beacon frame, an association frame, a reassociation frame, a TDLS setup request frame, and a TDLS response frame. Frames transmitted by STA124 may be received by AP122 and/or STA 126. Upon receiving the frame, AP122 and/or STA126 may probe QoS information field 208 in the received frame to determine whether STA124 is able to determine when to enter the sleep state based on communications with STA 126.

Fig. 2B is a diagram of an exemplary QoS information field format, according to an embodiment of the present invention. Fig. 2B is a schematic diagram of the exemplary QoS information field 208 presented in fig. 2. Referring to FIG. 2B, the QoS information field 208 may include an AC _ VO U-APSD flag field 214, an AC _ VI U-APSD flag field 216, an AC _ BK U-APSD flag field 218, an AC _ BE U-APSD flag field 220, a Q-Ack field 222, a maximum SP length field 224, and a more data Ack field 226. Exemplary AC _ VO U-APSD flags 214, AC _ VI U-APSD flags 216, AC _ BK U-APSD flags 218, AC _ BE U-APSD flags 220, Q-Ack 222, maximum SP length 224, and more data Ack 226 fields may BE generally described in one or more IEEE 802.11 standards and/or draft standards documents. In an exemplary embodiment of the invention, the AC _ VO U-APSD tag 214, AC _ VI U-APSD tag 216, AC _ BKU-APSD tag 218, AC _ BE U-APSD tag 220, Q-Ack 222, maximum SP length 224, and more data Ack 226 fields may each comprise a single bit. In various embodiments of the invention, the more data Ack field 226 may include an indicator value that may be set by the STA124 to a value indicating its ability to determine when to enter a sleep state based on communications with the STA 126. In an example embodiment of the invention, STA124 may set a binary value equal to 1 in the more data Ack field 226 to indicate that it is able to determine when to enter the sleep state based on communications with STA 126. If STA124 is unable to determine when to enter the sleep state based on communications with STA126, STA124 may set a binary value equal to 0 within more data Ack field 226 to indicate that it is unable to determine when to enter the sleep state based on communications with STA 126.

Upon entering the active state upon negotiating the start of the awake window duration, STA124 may determine that it has no data to send to STA 126. Based on the determination, STA124 may transmit frames to STA126 over RF channel 136. The transmitted frames may enable STA124 to communicate to STA126 that STA124 does not have data to transmit to STA 126. Fig. 3A is a diagram of an exemplary WLAN Medium Access Control (MAC) frame format, according to an embodiment of the invention. Referring to fig. 3A, an exemplary MAC frame 302 is shown that includes a frame control field 304, a duration/ID field 306, an address _1 field 308, an address _2 field 310, an address _3 field 312, a sequence control field 314, an address _4 field 316, a QoS control field 318, a frame body field 320, and an FCS field 322. Exemplary frame control 304, duration ID 306, address _1308, address _2310, address _3312, sequence control 314, address _4316, QoS control 318, frame body 320, and FCS 322 fields are generally described in one or more IEEE 802.11 standards and/or draft standard documents.

In various embodiments of the present invention, STA124 may utilize the frame control 304 and QoS control 318 fields in frames transmitted by STA124 to STA126 to communicate to STA126 that STA124 does not have data to transmit to STA 126. In an exemplary embodiment of the invention, the frames sent by STA124 to STA126 may comprise QoS null frames. In various embodiments of the invention, frame control field 304 may include one or more indicator values that may be set by STA124 to indicate that MAC frame 302 includes a QoS null frame. The QoS control field 318 may include one or more indicator values that may be set by the STA124 to send an ACK frame to the recipient of the QoS null frame, i.e., the STA126 communicating that the STA124 requests the STA126 to respond to the received QoS null frame.

Fig. 3B is a diagram of an exemplary WLAN QoS null frame format, according to an embodiment of the invention. Referring to fig. 3B, a QoS null frame 342 is shown. The QoS null frame 342 shown in fig. 3B indicates the fields from the MAC frame 302 that are used in the QoS null frame. The QoS null frame 342 includes a frame control field 304, a duration/ID field 306, an address _1 field 308, an address _2 field 310, an address _3 field 312, a sequence control field 314, a QoS control field 318, and an FCS field 322.

Fig. 4B is a diagram of an exemplary frame control field format, according to an embodiment of the invention. Fig. 4B is a diagram of the exemplary frame control field 304 presented in fig. 3A. Referring to fig. 4B, a frame control field 422 is shown. The frame control field 422 includes a protocol version subfield 424, a type subfield 426, a subtype subfield 428, a to DS subfield 430, a from DS (from DS) subfield 432, a more flags subfield 434, a retry subfield 436, a power management subfield 438, a more data subfield 440, a protection frame subfield 442, and an order subfield 444. Exemplary protocol version 424, type 426, subtype 428, to DS 430, from DS 432, more flags 434, retries 436, power management 438, more data 440, protection frames 442, and sequence 444 subfields are generally described in one or more IEEE 802.11 standards and/or draft standard files.

In various embodiments of the present invention, the type subfield 426 may include 2 bits, the subtype subfield 428 may include 4 bits and the more data subfield 440 may include units. In an example embodiment of the invention, STA124 may indicate that the transmitted frame includes QoS null frame 342 by setting the 2-bit binary value within type subfield 426 to 10 and the 4-bit binary value within subtype subfield 428 to 1100. Further, STA124 may set the binary value within more data subfield 440 to 0.

Fig. 3C is a diagram of an exemplary QoS control field format, according to an embodiment of the present invention. Fig. 3C is an illustration of the exemplary QoS control field 318 presented in fig. 3A. Referring to fig. 3C, a QoS control field 372 is shown. The QoS control field 372 includes a TID subfield 374, an EOSP subfield 376, an ACK policy subfield 378, a reserved subfield 380, and an AP PS buffer status subfield 382. The exemplary TID 374, EOSP 376, ACK policy 378, reservation 380, and AP PS buffer status 382 subfields are generally described in one or more IEEE 802.11 standards and/or draft standard files.

In various embodiments of the present invention, the EOSP subfield 376 may comprise unity and the AC policy subfield 378 may comprise 2 bits. In an exemplary embodiment of the invention, STA124 may indicate, in response to the transmitted QoS null frame 342, that an ACK frame from STA126 is expected by setting the 2-bit binary value in ACK policy subfield 378 to 00. Further, STA124 may set the binary value within EOSP subfield 376 to 0.

Fig. 4A is a diagram of an exemplary Acknowledgement (ACK) frame format, according to an embodiment of the invention. Referring to fig. 4A, an ACK frame 402 is shown. The ACK frame 402 shown in fig. 4A indicates the fields from the MAC frame 302 used in the ACK frame. The ACK frame 402 includes a frame control field 304, a duration field 306, an address _1 field 308, and an FCS field 322. Within the ACK frame 402, the address _1 field 308 may be referred to as a receive address.

In various embodiments of the invention, STA126 may send ACK frame 402 over RF channel 136 in response to QoS null frame 342 received from STA 124. In an example embodiment of the invention, STA126 may indicate that the transmitted frame includes ACK frame 402 by setting the 2-bit binary value in type subfield 426 to 01 and the 4-bit binary value in subtype subfield 428 to 1101.

In various embodiments of the invention, STA126 utilizes ACK frame 402 to communicate data that it does not have to send to STA 124. In an exemplary embodiment of the invention, the STA126 may indicate that it has no data to transmit by setting the binary value in the more data subfield 440 to 0. If STA126 determines that it has data to send to STA124, in an exemplary embodiment of the present invention, STA126 may communicate that it has data to send to STA124 by setting the binary value in the more data subfield 440 to 1.

If STA126 transmits ACK frame 402, in which more data subfield 440 includes a binary value of 0, STA126 may enter the sleep state after transmitting ACK frame 402 to STA124 over RF channel 136. In various embodiments of the invention, the STA126 may enter the sleep state prior to the end of the currently negotiated awake window duration. However, if there are additional STAs within the BSS 112, the STA126 may remain in an active state to determine whether there is data within the BSS 112 to exchange with any one of the remaining peer STAs. In various embodiments of the present invention, the STA126 may make this determination for each respective remaining peer STA by utilizing the methods and systems described herein. If the STA126 determines that there is no data to exchange with any remaining peer STAs, the STA126 may enter a sleep state.

If STA126 transmits ACK frame 402, in which more data subfield 440 includes a binary value of 1, STA126 may then transmit data to STA124 over RF channel 136. In this case, the STA126 may remain in the active state at least until the end of the currently negotiated awake window duration.

If STA126 receives data from STA124 over RF channel 136, STA126 may remain in the active state at least until the end of the currently negotiated awake window duration.

In various embodiments of the invention, if STA124 transmits QoS null frame 342 to STA126 and receives ACK frame 402 in response from STA126, STA124 may determine whether to remain in the active state based on the contents of the received ACK frame 402. In an exemplary embodiment of the invention, STA124 may exit the active state and enter the sleep state if ACK frame 402 includes a binary value of 0 within more data subfield 440. In various embodiments of the invention, the STA124 may enter the sleep state prior to the end of the currently negotiated awake window duration. However, if there are additional STAs within the BSS 112, the STA124 may remain in an active state to determine whether there is data within the BSS 112 to exchange with any one of the remaining peer STAs. In various embodiments of the present invention, STA124 may make this determination for each respective remaining peer SAT by utilizing the methods and systems described herein. If STA124 determines that there is no data to exchange with any remaining peer STAs, STA124 may enter a sleep state.

In an exemplary embodiment of the invention, if the received ACK frame 402 includes a binary value of 1 in the more data subfield 440, STA124 may remain in the active state at least until the end of the current awake window duration.

Fig. 5A is a diagram of an exemplary power state of an STA transmitting a QoS null frame according to an embodiment of the present invention. Referring to FIG. 5A, a power state diagram 500 is shown. Power state diagram 500 shows power levels represented on the vertical axis as the table above on the horizontal axisShown as a function of time. Relative to baseline power level p in power state diagram 500₀Representing the power level. In various embodiments of the present invention, p₀0. In an exemplary embodiment of the invention, the power state diagram 500 represents the power level of the STA 124. The exemplary narrative presented in fig. 5 is one in which STA124 enters an active state and sends a QoS null frame to STA 126. In response, STA126 sends an ACK frame to STA 124. In the ACK frame, STA126 indicates that it has no data to send to STA 124. After the reception of the ACK frame, the STA124 enters the sleep state.

Referring again to FIG. 5A, negotiating awake window duration may occur at time t₀And starting. The negotiated awake window duration is represented in fig. 5A as the duration of the awake window duration (negotiated). As shown in FIG. 5A, the duration of the awake window duration (negotiated) is at time t₀Is started at a time t₅And (6) terminating. STA124 may determine that it has no data to send to STA 126. At time t₀The STA may attempt to gain access to the communication medium to enable transmission of the signal. The duration during which STA124 may attempt to gain access to the communication medium is represented in fig. 5A as an access delay duration. As shown in fig. 5A, the access delay duration is at time t₀Is started and at time t₁And (6) terminating. The power level of STA124 during the access delay duration may be represented in fig. 5A by the RX power consumption of the power level.

Subsequent to time t after gaining access to the communication medium₁STA124 may then send a QoS null frame to STA 126. The duration during which STA124 may send QoS null frames is represented in fig. 5A as the send QoS null frame duration. As shown in FIG. 5A, the transmit QoS null frame duration begins at time t₁And ends at time t₂. The power level of STA124 during the transmit QoS null frame duration may be represented in fig. 5A by the TX power consumption of the power level.

After sending the QoS null frame, the time t₂STA124 may then expect to receive the QoS null frame sent in response theretoThe ACK frame is preceded by a determined time interval. This waiting duration is represented in fig. 5A as SIFS (short interframe space) duration. As shown in FIG. 5A, the SIFS duration begins at time t₂And ends at time t₃. During SIFS duration, the power level of STA124 may be represented in fig. 5A by the RX power consumption of the power level.

Following SIFS duration, following time t₃STA124 may then receive the ACK frame. The duration during which STA124 may receive an ACK frame is represented in fig. 5A as the receive ACK frame duration. As shown in FIG. 5A, the receive ACK frame duration begins at time t₃And ends at time t₄. The power level of STA124 during the receive ACK frame duration may be represented in fig. 5A by the RX power consumption of the power level.

Following the reception of an ACK frame, at time t₄STA124 may then enter a sleep state. The actual awake window duration during which STA124 is active is represented in fig. 5A as the duration of the awake window duration (actual). As shown in FIG. 5A, the duration of the awake window duration (actual) begins at time t_oAnd ends at time t₄. Once in the sleep state, the power level of STA124 may be represented in fig. 5A by the sleep power consumption of the power level.

Following the time t₄STA124 may remain in a sleep state until the end of the current wake interval duration. The duration during which STA124 remains in the sleep state is represented in fig. 5A as the sleep (actual) duration. As shown in FIG. 5A, the sleep (actual) duration begins at time t₄And ends at time t₆. The current wake-up interval duration is represented in fig. 5A as a wake-up interval. As shown in FIG. 5A, the wake-up interval begins at time t₀And ends at time t₆. Following the time t₆A subsequent wake interval duration may begin and the STA124 may exit the sleep state and enter the active state.

In various embodiments of the invention, the actual awake window duration may comprise a shorter duration than the negotiated awake window duration. Thus, in various embodiments of the invention, communication between STA124 and STA126 over RF channel 136 may enable STA124 to consume less power during the awake interval than if STA124 remained active throughout the negotiated awake window duration.

Fig. 5B is a diagram of an exemplary power state of an STA transmitting an ACK frame according to an embodiment of the present invention. Referring to fig. 5B, a power state diagram 550 is shown. The power state diagram 550 shows the power level represented on the vertical axis as a function of time represented on the horizontal axis. Relative to baseline power level p in power state diagram 550₀Representing the power level. In various embodiments of the present invention, p₀0. In an exemplary embodiment of the invention, the power state diagram 550 represents the power level of the STA 126. The exemplary narrative presented in fig. 5B is one in which STA126 enters an active state and receives QoS null frames from STA 124. In response, STA126 sends an ACK frame to STA 124. In the ACK frame, STA126 indicates that it has no data to send to STA 124. After the transmission of the ACK frame, the STA126 enters the sleep state.

Referring again to FIG. 5B, negotiating awake window duration may occur at time t₀And starting. The negotiated awake window duration is represented in fig. 5B as the duration of the awake window duration (negotiated). As shown in FIG. 5B, the duration of the awake window duration (negotiated) is at time t₀Is started and at time t₅And (6) terminating. STA126 may determine that it does not have data to send to STA 124. At time t₀The STA126 may monitor the communication medium to enable reception of the signal. The duration during which the STA126 may monitor the communication medium is represented in fig. 5B as a medium monitoring duration. As shown in FIG. 5B, the media monitoring duration is at time t₀Is started and at time t₁And (6) terminating. The power level of the STA126 during the medium monitoring duration may be represented in fig. 5B by the RX power consumption of the power level.

Following the duration of media monitoring, following time t₁STA126 may then receive the QoS null frame from STA 124. The duration during which the STA126 may receive the QoS null frame is represented in fig. 5B as the receive QoS null frame duration. As shown in FIG. 5B, the receive QoS null frame duration begins at time t₁And ends at time t₂. The power level of the STA126 during the receive QoS null frame duration may be represented in fig. 5B by the RX power consumption of the power level.

After receiving the QoS null frame, the time t₂STA126 may then wait for a determined time interval before sending an ACK frame to STA124 in response to the received QoS null frame. This wait duration is represented in fig. 5B as SIFS duration. As shown in FIG. 5B, the SIFS duration begins at time t₂And ends at time t₃. During SIFS duration, the power level of STA126 may be represented in fig. 5B by the RX power consumption of the power level.

Following SIFS duration, following time t₃STA126 may then send an ACK frame to STA124 over RF channel 136. The duration during which the STA126 may send an ACK frame is represented in fig. 5B as the send ACK frame duration. As shown in FIG. 5B, the transmit ACK frame duration begins at time t₃And ends at time t₄. The power level of STA126 during the transmit ACK frame duration may be represented in fig. 5B by the TX power consumption of the power level.

Following the transmission of the ACK frame, following the time t₄The STA126 may then enter a sleep state. The actual awake window duration during which STA126 is active is represented in fig. 5B as the duration of the awake window duration (actual). As shown in FIG. 5B, the duration of the awake window duration (actual) begins at time t₀And ends at time t₄. Once in the sleep state, the power level of the STA126 may be represented in fig. 5B by the sleep power consumption of the power level.

Following the time t₄STA 12B may holdIn a sleep state until the end of the current wake-up interval duration. The duration during which the STA126 remains in the sleep state is represented in fig. 5B as the sleep (actual) duration. As shown in FIG. 5B, the sleep (actual) duration begins at time t₄And ends at time t₆. The current wake-up interval duration is represented in fig. 5B as a wake-up interval. As shown in FIG. 5B, the wake-up interval begins at time t₀And ends at time t₆. Following the time t₆A subsequent wake interval duration may begin and the STA126 may exit the sleep state and enter the active state.

In various embodiments of the invention, the actual awake window duration may comprise a shorter duration than the negotiated awake window duration. Thus, in various embodiments of the invention, communication between the STA124 and the STA126 over the RF channel 136 may enable the STA126 to consume less power during the awake interval than if the STA126 remained active throughout the negotiated awake window duration.

Fig. 6 is a flowchart of exemplary steps for determining a power state of an STA transmitting a QoS null frame, according to an embodiment of the present invention. The exemplary narrative presented in fig. 6 is one in which STA124 enters an active state and determines whether it has data to send to STA 126. STA124 remains in the active state or enters the sleep state based on communications with STA 126.

Referring to fig. 6, in step 602, STA124 may start the awake window duration. At the beginning of the awake window duration, STA124 may exit the sleep state and enter the active state. In step 604, STA124 may determine whether it has buffered data to send to STA 126. The buffered data may include data generated during a previous sleep duration and stored by the STA124 for transmission to the STA126 during a subsequent awake window duration. If, at step 604, STA124 determines that it does not have buffered data to send to STA126, at step 606 STA124 may send a no data indication message to STA 126. In an exemplary embodiment of the present invention, the no data indication message may include a QoS null frame. If STA124 receives a data frame (including a QoS null frame) from STA126 with EOSP field 376 set to 1 prior to step 606, STA124 switches to step 704 in fig. 7 and may cancel its pending no data indication message and assume the role of STA 126. In step 608, STA124 may determine whether an ACK message has been received in response to the transmitted no data indication message. If STA124 determines that an ACK message has been received, at step 608, STA124 may determine whether STA126 has buffered data to send to STA124, at step 610. In this case, at step 610 STA124 determines that STA126 does not have any data to send to STA124, and at step 620 STA124 may determine whether any other peer STA has buffered data to send to STA 124. If, at step 620, STA124 determines that no other peer STA has buffered data to send to STA124, at step 622, STA124 may be in the sleep window duration. During the sleep window duration, STA124 may enter a sleep state.

If, at step 604, the STA determines that it has buffered data to send to STA126, at step 628, STA124 may send the buffered data to STA 126. In this case, STA124 may remain in the active state at least until the end of the negotiated awake window duration. Following step 628, at step 614, STA124 may determine whether the currently negotiated awake window duration has expired. At step 614, if the currently negotiated awake window duration has not expired, at step 616, STA124 may continue to exchange data with STA 126. Step 614 may immediately follow step 616. At step 614, if the currently negotiated awake window duration has expired, STA124 may begin negotiating the sleep window duration at step 618. The negotiated sleep window duration represents a duration immediately following the negotiated awake window duration during the current awake interval duration. During the negotiation of the sleep window duration, STA124 may exit the active state and enter the sleep state.

If at step 608 STA124 determines that an AC message has not been received, at step 624 STA124 may determine whether STA126 has sent data to STA 124. If STA124 determines that STA126 has sent data to STA124 at step 624, STA124 may receive data from STA126 at step 612. STA124 may remain in the active state at least until the end of the currently negotiated awake window duration. Step 614 may follow step 612.

At step 624, if STA124 determines that STA126 does not have data to send to STA124, STA124 may continue to wait to receive ACK frames from STA126 at least until the end of the currently negotiated awake window duration. At step 626, STA124 may determine whether the currently negotiated awake window duration has expired. At step 626, if STA124 determines that the currently negotiated awake window duration has expired, STA124 may discard the no data indication message if not successfully transmitted, and step 618 may follow step 626. If at step 626 STA124 determines that the currently negotiated awake window duration has not expired, at step 630 STA124 may determine whether an ACK message has been received from STA126 in response to the previously sent no data indication message.

At step 630, if STA124 determines that an ACK message has been received, step 624 may follow step 630. At step 630, if STA124 determines that the ACK message was not received, STA124 may again send a no data indication message to STA 126. In this case, step 606 may immediately follow step 606. In various embodiments of the invention, the STA124 may limit the number of retransmissions for which no data indication is present to a predetermined number of retransmissions. If an ACK is not received after STA124 has retransmitted the no-data indication message a predetermined number of retransmissions, STA124 may remain in the active state at least until the end of the currently negotiated awake window duration.

At step 620, if STA124 determines that one or more other peer STAs have buffered data to send to STA124, it may remain in the active state at least until the end of the currently negotiated awake window duration. Step 614 may immediately follow step 620.

Fig. 7 is a flowchart of exemplary steps for determining a power state of an STA receiving a QoS null frame, according to an embodiment of the present invention. The exemplary narrative presented in fig. 7 is one in which STA126 enters an active state to receive QoS null frames from STA 124. STA126 determines whether to remain in the active state based on whether it has data to send to STA 124.

Referring to fig. 7, in step 702, the STA126 may start the awake window duration. At the beginning of the awake window duration, the STA126 may exit the sleep state and enter the active state. In step 704, STA126 may receive a no data indication message from STA 124. In an exemplary embodiment of the present invention, the no data indication message may include a QoS null frame. At step 706, STA126 may determine whether it has buffered data to send to STA 124. If STA126 determines that it has data to send to STA124 at step 706, STA126 may send a data indication response message to STA124 at step 716. In an exemplary embodiment of the invention, the data indication response message may include an ACK frame that includes an indication that STA126 has data to send to STA 124.

If, at step 706, STA126 determines that it does not have data to send to STA124, at step 708, STA126 may send a no data indication response message to STA 124. In an exemplary embodiment of the invention, the data indication response message may include an ACK frame including an indication that STA126 has no data to send to STA 124. In step 710, the STA126 may determine whether there are other peer STAs. If, at step 710, the STA126 determines that no other peer STAs are present, the STA126 may begin the sleep window duration at step 712. During the sleep window duration, the STA126 may enter a sleep state.

If, at step 710, the STA126 determines that there are one or more remaining peer STAs, then, at step 714, the STA126 may evaluate each remaining peer STA. If the STA126 determines that there is data to be exchanged with one or more remaining peer STAs, the STA126 may remain in the active state at least until the end of the current awake window duration. If the STA126 determines that there is no data to exchange with any remaining peer STAs, the STA126 may be in the sleep window duration.

In various embodiments of the invention, the STA may practice one or more of the exemplary steps shown in fig. 6 and/or fig. 7, sequentially or in parallel.

Another embodiment of the present invention provides a non-transitory computer readable medium having stored thereon a computer program having at least one code section executable by a computer to cause performing the steps of unbuffered traffic indication for WLAN power saving described herein.

The present invention can be realized in hardware, software, or a combination of hardware and software. The present invention can be realized in a centralized fashion in at least one computer system, or in a distributed fashion where different elements are spread across several interconnected computer systems. Any kind of computer system or other apparatus adapted for carrying out the methods described herein is suited. A typical combination of hardware and software could be a general purpose computer system with a computer program that, when being loaded and executed, controls the computer system such that it carries out the methods described herein.

The present invention can also be implemented by a computer program product, which comprises all the features enabling the implementation of the methods of the invention and which, when loaded in a computer system, is able to carry out these methods. The computer program in the present document refers to: any expression, in any programming language, code or notation, of a set of instructions intended to cause a system having an information processing capability to perform a particular function either directly or after either or both of the following a) conversion to another language, code or notation; b) reproduced in different formats to implement specific functions.

While the invention has been described with reference to several particular embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims (26)

1. A method of power control, the method comprising:

establishing a peer relationship with one or more peer communication devices based on establishing an association with a disparate coordinating communication device;

transmitting a no data indication message to each of the one or more peer communication devices when operating in an active operating state;

receiving a no data indication response message from each of the one or more peer communication devices based on the transmitted one or more no data indication messages; and

entering a low power operating state based on the received one or more no data indication response messages.

2. The method of claim 1, comprising determining that there is no data to send to the one or more peer communications devices.

3. The method of claim 2, comprising generating the one or more no-data indication messages based on the determination.

4. The method of claim 1, comprising determining that at least one of the one or more peer communication devices has data to send based on the received one or more data indication response messages.

5. The method of claim 4, comprising remaining in the active operating state based on the determination.

6. The method of claim 1, comprising determining that none of the one or more peer communication devices has data to send based on the received one or more data indication response messages.

7. The method of claim 6, comprising entering the low power operating state based on the determination.

8. A method of power control, the method comprising:

establishing a peer relationship with one or more peer communication devices based on establishing an association with a disparate coordinating communication device;

receiving a no data indication message from each of the one or more peer communication devices when operating in an active operating state; and

entering a low power operating state based on the receiving.

9. The method of claim 8, comprising determining whether there is data to send to each of the one or more peer communication devices based on the received one or more no data indication messages.

10. The method of claim 9, comprising sending a no data indication response message to each of the one or more peer communication devices based on the determination when there is no data to send to any of the one or more peer communication devices.

11. The method of claim 10, comprising entering the low power operating state after said sending the one or more no data indication response messages.

12. The method of claim 9, comprising sending one or more data indication response messages based on the determination when there is data to send to at least one of the one or more peer communications devices.

13. The method of claim 12, comprising remaining in said active operating state after said sending said one or more data indication response messages.

14. A system for power control, the system comprising:

one or more circuits that enable establishment of a peer relationship with one or more peer communication devices based on establishment of an association with a disparate coordinating communication device;

when operating in an active operating state, the one or more circuits enable transmission of a no data indication message to each of the one or more peer communication devices;

based on the transmitted one or more no data indication messages, the one or more circuits enable reception of a no data indication response message from each of the one or more peer communication devices; and

the one or more circuits enable entry of a low power operating state based on the received one or more no data indication response messages.

15. The system according to claim 14, wherein said one or more circuits enable determining that there is no data to send to said one or more peer communication devices.

16. The system according to claim 15, wherein said one or more circuits enable generation of said one or more no-data indication messages based on said determination.

17. The system according to claim 14, wherein said one or more circuits enable a determination that at least one of said one or more peer communication devices has data to transmit based on said received one or more data indication response messages.

18. The system according to claim 17, wherein said one or more circuits enable remaining in said active operating state based on said determining.

19. The system according to claim 14, wherein said one or more circuits enable a determination that none of said one or more peer communication devices has data to send based on said received one or more data indication response messages.

20. The system according to claim 19, wherein said one or more circuits enable entry into said low power operating state based on said determination.

21. A system for power control, the system comprising:

one or more circuits that enable establishment of a peer relationship with one or more peer communication devices based on establishment of an association with a disparate coordinating communication device;

when operating in an active operating state, the one or more circuits enable receipt of a no data indication message from each of the one or more peer communication devices; and

based on the receiving, the one or more circuits enable entry of a low power operating state.

22. The system according to claim 21, wherein said one or more circuits enable determining whether there is data to be sent to each of said one or more peer communication devices based on said received one or more no data indication messages.

23. The system according to claim 22, wherein said one or more circuits enable sending a no data indication response message to each of said one or more peer communication devices based on said determination when there is no data to send to any of said one or more peer communication devices.

24. The system according to claim 23, wherein said one or more circuits enable entry into said low power operating state subsequent to said sending said one or more no data indication response messages.

25. The system according to claim 22, wherein said one or more circuits enable transmission of one or more data indication response messages based on said determination when there is data to be transmitted to at least one of said one or more peer communications devices.

26. The system according to claim 25, wherein said one or more circuits enable remaining in said active operating state subsequent to said transmitting said one or more data indication response messages.