System and method for medium access control in a power-save network

A method and apparatus for accessing, controlling and utilizing a network communication medium. Various aspects of the present invention may comprise a first networked device with power-save capability. The first networked device may acquire control of a communication medium utilizing a medium access protocol, which may be contention-based. The first networked device may utilize the communication medium to communicate information to a second networked device. The first networked device may transfer control of the communication medium to the second networked device, whereby the second networked device may control the communication medium without having to acquire control of the communication medium by utilizing the medium access protocol. The second networked device may utilize the communication medium to communicate information to the first networked device while maintaining control over the communication medium. The second networked device may have buffered such information for delayed delivery to the first networked device.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

SEQUENCE LISTING

FIELD OF THE INVENTION

The present invention relates generally to medium access control. More specifically, the present invention relates to method and apparatus for accessing, controlling and utilizing a communication medium in a network.

BACKGROUND OF THE INVENTION

Modern communication networks include a vast array of device types. Such device types may include, for example, wired and wireless devices, and stationary and portable devices. Some networked devices may have relatively limitless electrical power supplies, for example those drawing electrical power from wall outlets. Conversely, some networked devices may have limited power supplies, for example those operating on internal batteries.

Networked devices operating with limited power supplies may adopt operating characteristics that are conducive to conserving their limited supplies of power. For example, some devices may have an operating mode, sometimes called a “sleep mode” or “power-save mode,” where the device shuts down or slows down many of its internal functions to conserve energy. Such functions may include, for example, network communication functionality. Such devices may, for example, periodically or on-command exit the power-save mode and re-establish communications with other networked devices.

For example, a remote network device in power-save mode may exit the power-save mode and establish communications with a communication network access point. Once such communications are established, the exemplary remote network device and network access point may exchange information. For example, the remote device may transmit information to the access point that is destined for another networked device, and the access point may transmit information to the remote device that the access point has buffered for the remote device while the remote device was in power-save mode and unable to communicate with the access point.

The process of communicating information between the exemplary remote device and network access point, and between devices in general, consumes energy. Communication networks are generally governed by various communication procedures and protocols that control various communication functions. Such functions may include, for example, access to the communication medium and message queuing. Such communication protocols and other governing rules of information transfer typically include aspects that are inefficient with regard to, for example, power consumption, information transfer speed, and bandwidth utilization.

BRIEF SUMMARY OF THE INVENTION

Various aspects of the present invention provide a method and apparatus for accessing, controlling and utilizing a network communication medium. Various aspects of the present invention may comprise a first networked device with power-save capability. The first networked device may, for example, communicate an indication to various other network devices that the first networked device is capable of operating in a power-save mode.

Various aspects of the present invention may comprise the first networked device acquiring control of a network communication medium utilizing a medium access protocol, which may, for example, be a contention-based medium access protocol. The first networked device may, for example, acquire control of the communication medium after exiting from a sleep state of a power-save mode. The first networked device may utilize the communication medium to communicate information to a second networked device.

Various aspects of the present invention may comprise the first networked device transferring control of the communication medium to the second networked device, whereby the second networked device may control the communication medium without having to acquire control of the communication medium by utilizing the normal rules of the medium access protocol. The first networked device may, for example, transfer control of the communication medium to the second networked device by communicating a hand-off indication to the second networked device. Such a hand-off indication may comprise, for example, an indication that the second networked device may assume control over the communication medium. Following transfer of communication medium control to the second networked device, the first networked device may receive information from the second networked device, if the second networked device has such information to send. Following receipt of information from the second networked device, the first networked device may re-enter a sleep state of a power-save mode.

Various aspects of the present invention may comprise the second networked device assuming control of the communication medium following receipt of a medium control hand-off indication from the first networked device. The second networked device may, for example, accept a medium control hand-off from some networked devices, such as power-save devices, and not from other devices, such as non-power-save devices.

Various aspects of the present invention may comprise the second networked device, having assumed control of the communication medium, utilizing the communication medium to communicate information to the first networked device while maintaining control over the communication medium. The second networked device may, for example, communicate such information to the first networked device in a single data packet or stream of data packets. The second networked device may, for example, have buffered such information for delayed delivery to the first networked device.

These and other advantages, aspects and novel features of the present invention, as well as details of illustrative aspects thereof, will be more fully understood from the following description and drawings.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows a flow diagram of a method100for controlling access to and utilizing a communication medium in accordance with various aspects of the present invention. For example and without limitation, the method100may be implemented in a first device (e.g., a remote device with power-save capability) in a communication network. For the following discussion regardingFIG. 1, a device implementing the method100may be referred to generally as the “first device.”

The method100includes, at step110, waiting for an event to exit a sleep state of a power-save mode. Such an event may include, for example, a direct command from a user that requires a networked device operating in the sleep state of the power-save mode to exit the sleep state of the power-save mode. Such an event may include, for example, periodic expiration of a timer. Such an event may, in general, include any event that would cause a device to at least temporarily exit the sleep state of the power-save mode.

The method100then includes, at step120, the first device exiting the power-save mode. The exemplary method100illustrated inFIG. 1incorporates aspects associated with a networked device having power-save capability, because the power-save environment is a convenient environment in which to present some of the various aspects of the present invention. Accordingly, the scope of various aspects of the present invention should not be limited to characteristics of devices having power-save capabilities or a network having devices with power-save capabilities.

The method100, at step130, includes the first device acquiring access to and control of the network communication medium. Such access and control may include, for example, access and control of a single communication channel, such as, for example, a FDM frequency, a TDMA timeslot, a frequency hopping sequence, or a CDMA code. Such access and control may include, for example, access and control of a plurality of such communication channels. Such access and control may include, for example, access and control of all communication channels in a communication medium.

Such acquisition may include, for example, utilizing a contention-based medium access protocol to obtain access and control of at least a portion of a shared communication medium. For example, the first device may operate according to a carrier sense multiple access with collision avoidance (CSMA/CA) protocol to obtain control of the network communication medium. The first device may, for example in a wired network, obtain access to the communication medium utilizing a carrier sense multiple access with collision detection (CSMA/CD) protocol. Accordingly, the scope of various aspects of the present invention should not be limited to characteristics of a particular protocol or suite of protocols. Similarly, the scope of various aspects of the present invention should not be limited to characteristics of a particular communication medium or group thereof.

The method100, at step140, includes the first device utilizing the communication medium to communicate information to a second networked device. A first device that has no information to communicate to a second networked device may skip step140. Such information may include, for example, data or control information. Such information may be included in a single data packet or plurality of data packets. Such information may include, for example, unicast, multicast or broadcast information. The information communication may or may not include packet acknowledgement indications from the receiver of the communicated information. Accordingly, the scope of various aspects of the present invention should not be limited to characteristics of particular information format or type. Nor should the scope of various aspects of the present invention be limited to characteristics of a particular communication mechanism.

Note that step140may include utilizing typical medium access safeguards, such as time limits, to maintain communication discipline in the communication network. For example, step140need not enable the first device to control the communication medium in an uninterrupted fashion until the device has no more information to communicate. Such unchecked control could, in particular scenarios, have detrimental effects on the communication network. Accordingly, for example, the network may place constraints on the duration for which a device or group of devices may maintain control over the communication medium or portions thereof.

The method100, at step150, includes the first device passing control of the communication medium to a second networked device. Having received such medium control from the first device, the second device may then utilize the communication medium for communicating information traffic without having to perform various medium access activities, such as, for example, contending with other networked devices for access to the communication medium. For example and without limitation, if the first device communicates information at step140to a second device (e.g., a network access point), the first device may, at step150, pass control of the communication medium to the second device or to some other networked device.

The first device may pass control of the communication medium to a second device in a variety of ways. For example, the first device may communicate an explicit notification to the second device indicating that the second device may assume control over the communication medium. Alternatively, such a notification may be incorporated into a packet that the first device communicates to the second device or another networked device. Such a packet may also include, for example, control information and/or data information. Accordingly, the scope of various aspects of the present invention should not be limited to characteristics of a particular mechanism of passing control of the communication medium.

In an exemplary power-save environment, a remote power-save device may notify a network controlling entity or access point that the power-save device has power-save capability. Then, upon the power-save device sending a packet to the access point indicating that the power-save device has no data or no more data to send, the access point may automatically assume control of the communication medium for sending downstream traffic to the power-save device.

The access point may, for example, distinguish between power-save devices and non-power-save devices in its network and interact with each type of device in a different manner. For example, the exemplary access point may choose not to accept control from the remote device if the access point determines that the remote device does not have power-save capability.

The method100, at step160, includes receiving information from the second device, which received control of the communication medium at step150. Of course, in a scenario where the second device has no information to communicate, step160may be skipped. Such information is not to be limited to a particular type of data or data format. For example, such information may take the form of several discrete packets of information, which include data and/or control information. The second device may, for example, communicate one or more discrete packets to the first device while maintaining control of the communication medium.

As mentioned previously with regard to communications from the first device, the network may utilize various mechanisms to ensure that the second device does not retain control of the communication medium for an unduly long period. For example and without limitation, in a communication system that places an upper limit on the time that a particular device may control the communication medium, such a communication system incorporating medium access control in accordance with various aspects of the present invention may place such a limit on the combined time for which the first and second devices may control the communication medium.

In an exemplary power-save network environment, the second device may be a network access point that has buffered traffic destined for the power-save device while the power-save device was in a sleep state of a power-save mode. In general, the second device may include any networked entity that has traffic to deliver to the first device. In a communication scenario where the second device has no information to communicate to the first device, the method100flow may by-pass step160. Note that the scope of various aspects of the present invention should not be limited to receiving a particular type of information or receiving information from a particular type of network entity.

The method100, at step170, includes notifying a user of recently transferred information. For example, a remote device may notify the user of the remote device that the remote device has recently received updated information from the network. The user may, for example, control the existence, nature and timing of such a notification. For example, the user may specify that the device is not to notify the user. Alternatively, for example, the user may specify that the device is only to notify the user of updates regarding particular types of information. Accordingly, the scope of various aspects of the present invention is not to be limited to the existence of such a notification or the nature of any notification provided.

The method100, at step180, includes the first device re-entering the sleep state of the power-save mode. In the exemplary power-save environment, having exchanged information with the network access point, the first device may re-enter the sleep state of the power-save mode. The method100flow may then return to method step110, where the first device again waits for an event to cause the first device to exit the sleep state of the power-save mode. As mentioned earlier, the power-save network environment is for illustrative purposes and should not limit the scope of various aspects of the present invention to characteristics of power-save devices or networks including such devices.

FIG. 2shows a flow diagram of a method200for controlling access to and utilizing a communication medium in accordance with various aspects of the present invention. For the following discussion regardingFIG. 2, a device implementing the method200may be referred to generally as the “first device.” The first device may include, for example and without limitation, an access point device in a communication network. For the following discussion, a device implementing the method200may be referred to generally as the “first device.”

The method200, at step210, includes receiving information from a second device. The second device may have acquired access to the communication medium by performing steps of a medium access protocol (e.g., a contention-based medium access protocol). Step210includes various sub-steps, which may or may not be followed by the first device depending on the particular communication scenario. Step210may include at step212, for example, receiving an initial packet from the second device. Step210may also include at step214, for example, receiving additional information packets from the second device.

In one exemplary scenario, the first device may perform step214when the second device has more information to communicate to the first device than can reasonably be packaged in a single packet. System packet size constraints may also limit packet size. Step210may further include at step216, for example, receiving an indication from the second device that the first device may assume control of the communication medium. Such an indication may be an explicit directive or may, for example, be an indication that the second device has no data or no more data to send to the first device.

The various information-receiving steps discussed previously are exemplary and should not limit the scope of various aspects of the present invention. For example, the initial packet communicated at step212may be the only packet communicated to the first device. That initial packet may, for example, include data information, control information, and the indication that the first device is to take control of the communication medium. Accordingly, the scope of various aspects of the present invention should not be limited to a particular packet or message format or packet stream format.

The exemplary method200, as will be discussed below, is shown accepting control of the communication medium from network devices having power-save capability and not from network devices that to not have power-save capability. It should be noted that various aspects of the present invention should not be limited to various characteristics of this exemplary model. For example, various aspects of the present invention apply equally well to networked devices that have and do not have power-save capability.

The exemplary method200, at step220, includes determining if the second device is a power-save device. Such a determination may be made in a variety of ways. For example, the second device may have previously registered with the network as having power-save capability and may be listed in a database as having such capability. Also, for example, the second device may incorporate indications of its power-save capability in various messages sent by the second device to the first device. Accordingly, the scope of various aspects of the present invention shall not be limited by a particular method of indicating power-save capability or a particular method of determining whether a networked device has power-save capability.

If the second device is not a power-save device, the exemplary method200flow continues at step250, which will be discussed below. If the second device is a device having power-save capability, the method200flow continues at step230.

The method200, at step230, includes determining whether there is traffic waiting to be communicated to the second device. For example, the first device, which may for example be a network access point, may have stored message traffic destined for the second device in a buffer. The first device may have performed such storage, for example, if the second device is a registered power-save device. If there is no traffic to be sent to the second device, the exemplary method200flow continues at step250, which will be discussed below. If there is traffic to be communicated to the second device, the method200flow continues at step240.

The method200, at step240, includes communicating information traffic to the second device. Step240includes various sub-steps, as illustrated inFIG. 2, that may or may not be followed depending on the particular communication scenario. The method200, at step242, includes accepting control of the communication medium that was passed from the second device at step216. By accepting control of the communication medium passed from the second device, the first device may by-pass having to perform various medium access acquisition tasks, such as, for example, contending with other network devices for access to the communication medium. For example and without limitation, if the communication medium is generally governed by a contention-based medium access protocol, the first device may immediately begin communicating information back to the second device instead of having to queue the information and contend for access to the communication medium for each information packet to be sent to the second device.

As discussed previously, the exemplary method200does not accept a communication medium control hand-off from a non-power-save device. However, as also discussed previously, the scope of various aspects of the present invention should not be limited to only accepting medium control hand-off from power-save devices.

The method200, at step247, includes retrieving information traffic destined for the second device that may have been stored in a buffer. Such information retrieval may have latency that does not provide for meeting the message timing requirements of the system. Accordingly, the exemplary method200includes an exemplary mechanism at steps244and246by which control of the communication medium may be maintained and the second device may be notified that information is coming in spite of such latency. The method200, at step244, determines whether the information retrieval latency is too great to meet the communication medium protocol's messaging timing requirements. If step244determines that the buffered information will not be retrieved in time to meet the communication medium protocol's messaging requirements, method200flow continues to step246. Step246, in turn, includes communicating a message over the communication medium to the second device that indicates information will eventually follow. The mechanism discussed above to compensate for information retrieval latency is exemplary. The method200may employ a variety of alternative mechanisms to handle such latency. Accordingly, the scope of various aspects of the present invention should not be limited to characteristics of a particular latency handling mechanism.

When the first device has retrieved information destined for the second device, at step247, and the first device is ready to communicate retrieved information to the second device, the method200, at step248, communicates the retrieved information to the second device. The first device may, for example, communicate the information over the communication medium while maintaining control of the communication medium. Step248may, for example, communicate the information to the second device in one packet or a plurality of packets. Accordingly, the scope of various aspects of the present invention should not be limited to a particular message or packet format or packet stream format.

After the first device has communicated the information to the second device at step248, the method200, at step250, releases control of the communication medium. Such release may include, for example, communicating an explicit release message or may include, for example, remaining silent for a predetermined period of time in accordance with the rules of medium access for the particular communication medium in use. Accordingly, the scope of various aspects of the present invention should not be limited to a particular medium control release mechanism.

As discussed previously, the communications between the first and second devices may be subjected to various communication network safeguards, such as time constraints, to ensure that other networked devices have fair access to the communication medium.

FIG. 3illustrates a first exemplary message exchange300between two networked devices in accordance with various aspects of the present invention. The exemplary message exchange300is provided in the context of the IEEE 802.11 standard. However, by no means, should the scope of various aspects of the present invention be limited to IEEE 802.11 features and implementations.

The top row of the message exchange300is labeled “QSTA.” This generally refers to a quality of service station in the IEEE 802.11 context. The QSTA may be generally thought of, for this example, as a first networked device that may have power-save capabilities. The bottom row of the message exchange300is labeled “QAP.” This generally refers to a quality of service access point in the IEEE 802.11 context. The QAP may be generally thought of, for this example, as a second networked device.

Prior to the exemplary message exchange300, the QSTA gains access to and control of the communication medium. For example, the QSTA may acquire access to the communication medium following a contention-based medium access protocol, such as CSMA/CA.

The message (or packet) exchange300begins with a first message310sent from the QSTA to the QAP. The first message310may, for example, be a Q-Data message with the More flag set. Such an exemplary first message310may communicate data to the QAP and also indicate to the QAP, in a power-save scenario, that the QSTA is not currently in a sleep state of a power-save mode.

Following an inter-frame spacing interval (SIFS), the message exchange300includes the QAP sending a second message320to the QSTA. The second message320may, for example, be an acknowledgement message (ACK) to indicate to the QSTA that the QAP successfully received the first message310.

The message exchange300then includes a third message330from the QSTA to the QAP. The third message330may, for example, be a Q-Data message with the More flag unset. The unset More flag may indicate to the QAP that the QSTA has no more data to send to the QAP. The unset More flag may also, for example, indicate a handoff of control of the communication medium from the QSTA to the QAP.

As discussed previously, the QAP, at this point, may treat power-save devices differently than non-power-save devices. For example, if the QAP determines that the QSTA is not a power-save device, the QAP may merely acknowledge receipt of the third message330and cease communicating with the QSTA, thereby releasing the communication medium. Conversely, if the QAP determines that the QSTA is a power-save device, the QAP may accept control of the communication medium from the QSTA, for example, for the communication of information traffic back to the QSTA.

At this point in the exemplary message exchange300, the QAP assumes control over the communication medium. The QAP responds by sending a fourth message340to the QSTA. The fourth message340may, for example, be a Q-Data message that includes data for the QSTA and an indication acknowledging receipt of the third message330.

The exemplary message exchange300then includes a fifth message350from the QSTA to the QAP, which may, for example, acknowledge receipt of the fourth message340. The message exchange300then includes a sixth message360from the QAP to the QSTA, which may, for example, include additional data for the QSTA. The message exchange300then includes a seventh message370from the QSTA to the QAP, which may, for example, include an indication acknowledging receipt of the sixth message360.

The exemplary message exchange300may continue with the QSTA and the QAP exchanging information, for example, until the QAP exhausts its supply of information to be communicated to the QSTA. Alternatively, for example, the QSTA and QAP may discontinue the message exchange300due to expiration of a medium access time limit or other medium access control mechanism, or due to other considerations regarding fairness of access or attempts to guarantee good quality of service to the collection of QSTA within the network.

FIG. 4illustrates a second exemplary message exchange400between two networked devices in accordance with various aspects of the present invention. As with the exemplary message exchange300illustrated inFIG. 3, the second exemplary message exchange400is provided in the context of the IEEE 802.11 standard. However, by no means, should the scope of various aspects of the present invention be limited to IEEE 802.11 features and implementations.

The top row of the message exchange400is labeled “QSTA.” This generally refers to a quality of service station in the IEEE 802.11 context. The QSTA may be generally thought of, for this example, as a first networked device that may have power-save capabilities. The bottom row of the message exchange400is labeled “QAP.” This generally refers to a quality of service access point in the IEEE 802.11 context. The QAP may be generally thought of, for this example, as a second networked device.

Prior to the exemplary message exchange400, the QSTA gains access to and control of the communication medium. For example, the QSTA may acquire access to the communication medium following a contention-based medium access protocol, such as CSMA/CA.

The message (or packet) exchange400begins with a first message410sent from the QSTA to the QAP. The first message410may, for example, be a Q-Data message with the More flag unset. Such a first message410may, for example, indicate to the QAP in a power-save scenario that the QSTA is not currently operating in a sleep state of a power-save mode and is standing by to receive traffic that the QAP may have been buffering for the QSTA while the QSTA was in a sleep state of a power-save mode. The unset More flag may also indicate a handoff of control of the communication medium from the QSTA to the QAP.

As discussed previously, the QAP, at this point, may treat power-save devices differently than non-power-save devices. For example, if the QAP determines that the QSTA is not a power-save device, the QAP may merely acknowledge receipt of the first message410and cease communicating with the QSTA, thereby releasing the communication medium. Conversely, if the QAP determines that the QSTA is a power-save device, the QAP may accept control of the communication medium from the QSTA for the communication of information traffic, for example, from the QAP to the QSTA.

At this point in the exemplary message exchange400, the QAP assumes control over the communication medium. Following an inter-frame spacing interval (SIFS), the message exchange400includes the QAP sending a second message420to the QSTA. The second message420may, for example, include an acknowledgement indication (ACK) to indicate to the QSTA that the QAP successfully received the first message410.

Additionally, for example, the second message420may include a null data frame, which may indicate to the QSTA that the QAP has information traffic buffered for delivery to the QSTA, but that the QAP needs additional time to acquire the information from the buffer. Such a null data frame may, for example, allow the QAP to retain control of the communication medium (e.g., a communication medium controlled by a contention-based medium access control protocol) while the QAP is obtaining the information traffic destined for the QSTA.

The exemplary message exchange400then includes a third message430from the QSTA to the QAP. The third message430may, for example, include an indication to acknowledge receipt of the second message420by the QSTA.

The message exchange400then includes a fourth message440from the QAP to the QSTA, which may, for example, include information for the QSTA that the QAP retrieved from a buffer. The message exchange400then includes a fifth message450from the QSTA to the QAP, which may, for example, include an indication acknowledging receipt of the fourth message440.

The message exchange400then includes a sixth message460from the QAP to the QSTA, which may, for example, include additional information for the QSTA that the QAP retrieved from a buffer. The message exchange400then includes a seventh message470from the QSTA to the QAP, which may, for example, include an indication acknowledging receipt of the sixth message460.

The exemplary message exchange400may continue with the QSTA and the QAP exchanging information, for example, until the QAP exhausts its supply of information to be communicated to the QSTA. Alternatively, for example, the QSTA and QAP may discontinue the message exchange400due to expiration of a medium access time limit or due to some other form of medium access control mechanism, or due to other considerations regarding fairness of access or attempts to guarantee good quality of service to the collection of QSTA within the network.

FIG. 5shows a block diagram of a system500for controlling access to and utilizing a communication medium in accordance with various aspects of the present invention. The system500includes a first communication module510, which may, for example, be utilized by a first networked device. Various components of the first communication module510may, for example, perform various aspects of the method100illustrated inFIG. 1. The system500also includes a second communication module540, which may, for example, be utilized by a second networked device. Various components of the second communication module540may, for example, perform various aspects of the method200illustrated inFIG. 2. For the following discussion regardingFIG. 5, a network device utilizing the first communication module510may be referred to as the “first device,” and a device utilizing the second communication module540may be referred to as the “second device.”

The first communication module510includes a power-save module505. The power-save module may control the first device entering and exiting a power-save mode. For example, the power-save module505may automatically place the first device into a sleep state of a power-save mode when the power-save module505detects no user interaction with the first device for a period of time. Also for example, the power-save module505may automatically place the first device into a wake state of a power-save mode periodically based on the timeout of a wake-up timer. Alternatively, the power-save module505may place the first device in the wake state when the module505detects an attempt at user interaction with the first device. Accordingly, the scope of various aspects of the present invention should not be limited to particular characteristics and implementations of power-save functionality.

The first communication module510includes a transceiver module515. The transceiver module515may communicate with various network devices over a variety of communication links. For example and without limitation, the transceiver module515may communicate with another networked device over a wired link, wireless link, electrical link, radio frequency link, tethered optical link, or non-tethered optical link. Accordingly, the scope of various aspects of the present invention should not be limited by characteristics of a particular type of transceiver or communication link.

The first communication module510includes a medium access control (MAC) module520. The exemplary MAC module520is communicatively coupled to the power-save module505and the transceiver module515. The general function of the MAC module520is to control access to and control the network communication medium. Such access may include, for example, acquiring access and control of a channel of the communication medium, such as a time slot of a communication medium governed by TDMA, a frequency of a communication medium governed by FDM, a frequency hopping sequence, or a code of a communication medium governed by CDMA. To this end, the MAC module520includes a medium access module522that performs communication medium access functionality. Alternatively, acquiring access to and control of the network communication medium may include, for example, gaining access to and control of a plurality of communication channels or all of the communication channels.

For example, the medium access module522may utilize the transceiver module515to acquire access and control of a communication medium by utilizing any of a variety of communication medium access protocols. For example and without limitation, the medium access module522may acquire medium access and control according to a carrier sense multiple access with collision avoidance (CSMA/CA) protocol. Alternatively, the medium access module522may, for example, acquire access to the communication medium according to an ALOHA or a CSMA/CD protocol. Accordingly, the scope of various aspects of the present invention should not be limited to characteristics of a particular medium access protocol.

The exemplary MAC module520also includes a communication medium control-passing module521. After the medium access module522has gained access and control of the communication medium, the control-passing module521may pass control of the communication medium to another networked device. Such a networked device may, for example, include a second networked device utilizing the second communication module540(the “second device). After the second device receives control of the communication medium from the first device, the second device may then utilize the communication medium without having to perform various medium access activities, such as, for example, contending with other network devices for access and control of the communication medium.

The exemplary MAC module520may also communicate to various network devices that the first device has the capability to enter and exit a sleep state of a power-save mode. Other network devices may then utilize this information to govern their treatment of and communication with the first device.

Note that the MAC module520may incorporate various safeguards generally associated with medium access, including for example, timeout functions to ensure fair access to the communication medium for all network devices. Thus, the MAC module520may include various aspects to ensure that the first device may not control the communication medium for an inappropriate amount of time.

The control-passing module521may pass control of the communication medium to another networked device in a variety of ways. For example, the control-passing module521may utilize the transceiver module515to communicate an explicit message to another device transferring control of the communication medium to the other device. Alternatively, for example, the control-passing module521may utilize the transceiver module515to communicate a null data frame to another device, thus signifying that the first device is no longer utilizing the communication medium and that the other device may then take control of the communication medium.

The first communication module510also includes a data communication module530that is coupled to the MAC module520, the transceiver module515and the power-save module505. After the MAC module520gains access to and control of a communication medium, the data communication module530may utilize the transceiver module515to communicate information to another networked device. For example, in the illustrative system500shown inFIG. 5, the data communication module530may utilize the transceiver module515to communicate with the second device. The data communication module530may, for example, utilize the transceiver module515to communicate a single packet or a stream of packets to the second device.

The data communication module530may also perform various data receiving functions. For example, following transfer of control of the communication from the first device to the second device, the data communication module530may utilize the transceiver module515to receive information communicated to the first device from the second device, which now has control of the communication medium. Such information may, for example, be in the form of a single data packet or a stream of data packets.

Further, the data communication module530may communicate with the power-save module505to indicate to the power-save module505when communication between the first device and the second device is complete, thereby allowing the power-save module505to decide whether to cause the first device to enter a sleep state of a power-save mode.

Various modules of the first communication module510may, for example, be incorporated into a single integrated circuit. Various modules may include hardware, software, or combinations thereof. Various modules may also share components of the communication module510, such as, for example, a microprocessor, memory devices, bus infrastructure, clocks, etc. Accordingly, the scope of various aspects of the present invention should not be limited to particular arrangements and implementations of the various modules discussed.

Though not illustrated inFIG. 5, the first communication module510may also include various user interface modules, which may, for example, indicate to the user whether the device is in a power-save mode. The various user interface modules may also indicate to a user that the device has recently received updated information. Such modules may provide the user with the ability to tailor user interface interaction with the device in the manner best suited to the individual user. Accordingly, the scope of various aspects of the present invention should by no means be limited to various user interface modes, functions or features.

The second communication module540is illustrated connected to a wired LAN544through a wired LAN module542. The second communication module540may, for example, be utilized in a network access point device. However, the scope of various aspects of the present invention should not be limited to a particular type of network device.

The second communication module540includes a transceiver module550. The transceiver module550may communicate with various network devices over a variety of communication links. For example and without limitation, the transceiver module550may communicate with another networked device over a wired link, wireless link, electrical link, radio frequency link, tethered optical link, or non-tethered optical link. Accordingly, the scope of various aspects of the present invention should not be limited by characteristics of a particular type of transceiver or communication link.

The second communication module540also includes a MAC module560, which is communicatively coupled to the transceiver module550. Similar to the MAC module520discussed previously with respect to the first communication module510, the exemplary MAC module560includes a medium access module562. The medium access module562may, for example, share various aspects with the medium access module522discussed with regard to the first communication module510.

The MAC module560also includes a control-passing module564. The control-passing module564may utilize the transceiver module550to receive a message from the first device passing control of the communication medium from the first device to the second device. Having acquired control of the communication medium in this manner, the MAC module560may access and control the communication medium without having to perform various medium access activities. For example, if access to the communication medium is generally governed by a contention-based medium access protocol, such as, for example, CSMA/CA, the MAC module560may acquire control directly from the first device, thereby by-passing the need to contend with other network devices for access to the communication medium.

The second communication module540also includes a data communication module580that is communicatively coupled to the transceiver module550and the MAC module560. The data communication module580may, for example, utilize the transceiver module550to receive information from networked devices. The data communication module580may also, for example, utilize the transceiver module550to communicate information to other networked devices.

For example, prior to the MAC module560gaining control of the communication medium from the first device passing control of the communication medium to the second device, the data communication module580may utilize the transceiver module550to receive information from the first device. Such information may include data and/or control information, and may also include a medium access hand-off message. Such a medium access hand-off message may also, for example, be a stand-alone message.

Also for example, subsequent to the MAC module560gaining control of the communication medium from the first device passing control of the communication medium to the second device, the data communication module580may utilize the transceiver module550to communicate information back to the first device. In the illustrative example of the second device being a network access point device, the access point device may have been storing information destined for the first device in a buffer and awaiting instructions from the first device or an indication that the first device is not in a sleep state of a power-save mode.

The data communication module580is shown communicatively coupled to a message buffer590, in which may be stored information destined for the first device. The data communication module580may retrieve such information from the message buffer590and utilize the transceiver module550to communicate the information to the first device. The data communication module580may, for example, communicate such information to the first device by communicating a single data packet or a stream of data packets to the first device, while the MAC module560maintains control of the communication medium. Note that the message buffer590may be incorporated into the second communication module540or not. For example, the message buffer590may be at another location accessible on the wired LAN544.

The second communication module540includes a power-save device database module570, which is communicatively coupled to the power-save determination module566of the MAC module560. The power-save determination module566(e.g., in coordination with the control-passing module564) may utilize the information in the power-save device database module570to determine if a received medium control hand-off message was transmitted by a network device with power-save capability. For example, the second communication module540may respond to such a message differently depending on the message source. For example, the second communication module540may decide not to accept control of the communication medium in response to messages received from networked devices that do not have power-save capability. Conversely, the second communication module540may, for example, always accept control of the communication medium in response to medium control hand-off messages received from networked devices that are power-save devices.

Various modules of the second communication module540may, for example, be incorporated into a single integrated circuit. Various modules may include hardware, software, or combinations of hardware and software. Various modules may also share components of the second communication module540, such as, for example, a microprocessor, memory devices, bus infrastructure, clocks, etc. Accordingly, the scope of various aspects of the present invention should not be limited to particular arrangements and implementations of the various modules discussed.

FIG. 6shows a flow diagram of a method600for controlling access to a communication medium in accordance with various aspects of the present invention. The exemplary method600is presented in the context of a communication network having a networked device with power-save capability. However, the scope of various aspects of the present invention should, by no means, be limited to characteristics of such power-save devices or a network having such devices. Additionally, the exemplary method600may incorporate various aspects of the exemplary methods100,200shown inFIGS. 1 and 1and discussed previously.

The method600, at step610, includes a first networked device exiting a sleep state of a power-save mode. The first networked device may exit the sleep state of the power-save mode for a variety of reasons, including but not limited to, user activity or timer activity. In an alternative scenario, for example, the first networked device may complete some other activity with which it was pre-occupied.

The method600, at step620, then includes the first networked device gaining access to and control of the network communications medium. As discussed previously such access and control may, for example, correspond to one or more channel, frequency, timeslot, frequency hopping pattern, or code. The first networked device may, for example, utilize a contention-based medium access protocol (e.g., CSMA/CA) to gain access to the communication medium.

The method600, at step630, includes the first networked device utilizing the communication medium to communicate information to a second networked device. The second networked device may be, for example, an access point device in a wireless network. Alternatively, the second networked device may be, for example, a peer device. Accordingly, the scope of various aspects of the present invention should, by no means, be limited to characteristics of particular devices or networks.

Step630may include the first networked device communicating information to the second networked device in a data packet or a plurality of data packets. In an exemplary scenario, where after acquiring access to and control of the communication medium at step620, the first networked device has no information to communicate to the second networked device, the first networked device may by-pass step630.

The method600, at step640, includes passing control of the communication medium from the first networked device to a second networked device. The second networked device may, for example, be the same networked device to which the first networked device communicated information in step630. The second networked device, having thereby gained control of the communication medium, may then utilize the communication medium without having to follow the medium access protocol generally governing access to the communication medium. For example and without limitation, in a scenario where access to the communication medium is generally governed by a contention-based medium access control protocol (e.g., CSMA/CA), the second networked device may utilize the communication medium without having to contend with other networked devices for access to the communication medium.

Step640is illustrated having two exemplary sub-steps. Step642includes the first networked device communicating a medium control hand-off message to the second networked device. The medium control hand-off message may, for example, notify the second networked device that the second networked device may have control over the communication medium. The medium control hand-off message may have a variety of forms. For example, the hand-off message may be a stand-alone message or may be a flag in a multi-purpose message. For example, the hand-off message may be a flag in a packet containing data and/or control information, which may be set to indicate to the receiving device that the sending device has no data or no more data to send.

Step644includes the second networked device, which received the hand-off message, verifying that the first networked device is a power-save device. In the exemplary method600, the second networked device may distinguish between power-save and non-power-save devices. For example, the second networked device may only accept a medium control hand-off from a power-save device and not from a non-power-save device. Note that allowing hand-off from a power-save device and not allowing hand-off from a non-power-save device is an exemplary scenario and should, by no means, limit the scope of various aspects of the present invention.

Step644may include, for example, the second networked device analyzing messages from the first networked device to determine whether the first networked device is a power-save device. Alternatively, the second networked device may access a database of known power-save devices to determine if the first networked device is a power-save device. The second networked device may perform such verification in a variety of ways, and the scope of various aspects of the present invention should not be limited by characteristics of particular verification mechanisms.

The method600, at step650, includes the second networked device, having acquired control over the communication medium at step640, utilizing the communication medium to communicate information. For example, the second networked device may communicate information back to the first networked device.

In an exemplary power-save scenario, the second networked device may have stored traffic destined for the first networked device in a buffer, waiting for an indication that the first networked device is not in a sleep state of a power-save mode. The second networked device may then, for example, having received an indication that the first networked device is not in a sleep state of a power-save mode, and having just received control of the communication medium from the first networked device, retrieve such stored information from the buffer and utilize the communication medium to communicate the retrieved information to the first networked device.

Step650may include, for example, communicating information to the first networked device, or other networked device, using a single packet or a stream of packets. Step650may include communicating such information over the communication medium while maintaining control over the communication medium. The method600thereby provides a mechanism whereby a first and second networked device may communicate information with each other following only one successful acquisition of access to and control of the communication medium.

The method600, at step660, includes the second networked device releasing control of the communication medium. Step660may include, for example, the second networked device communicating a message explicitly indicating that the second networked device is releasing control of the communication medium. Alternatively, for example, step660may include the second networked device discontinuing its utilization of the communication medium. Accordingly, the scope of various aspects of the present invention should not be limited by characteristics of particular mechanisms for releasing control of the communication medium.

Note that the medium access control for the communication medium may include safeguards to keep a networked entity or set of networked entities from controlling the communication medium for an inappropriate period of time. For example, the medium access protocol may include an upper time limit on the time that a device or group of devices may maintain uninterrupted control of the communication medium.

In summary, a system and method are provided for accessing, controlling and utilizing a communication medium in a network. While the invention has been described with reference to certain aspects and 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.