WO2013171653A1

WO2013171653A1 - Method and apparatus for signalling in wireless communication systems

Info

Publication number: WO2013171653A1
Application number: PCT/IB2013/053872
Authority: WO
Inventors: Juho Pirskanen; Timo Koskela; Anna Pantelidou; Sami-Jukka Hakola; Samuli Turtinen
Original assignee: Renesas Mobile Corporation
Priority date: 2012-05-14
Filing date: 2013-05-13
Publication date: 2013-11-21

Abstract

A method, apparatus and computer program product are provided for enabling wireless data transmission. In this regard, a method is provided that comprises causing a PS-Poll, modified PS-Poll, or group operation transmission. The method of this embodiment may also include receiving a message from an access point in response to the PS-Poll, modified PS-Poll, or group operation transmission, the response message configured to indicate grouping parameters used with communication devices.

Description

METHOD AND APPARATUS FOR SIGNALLING IN WIRELESS

COMMUNICATION SYSTEMS

TECHNOLOGICAL FIELD

[0001] Embodiments of the present invention relate generally to communications technology and, more particularly, to signaling in wireless data transmissions.

BACKGROUND

[0002] Typical wireless networks, such as networks conforming to one of the Institute of Electrical and Electronics Engineers (IEEE) 802.1 1 standards, are arranged such that a plurality of communications devices each has a wireless connection to an access point. Typically, all of the communications devices communicate on the same channel (e.g. in the same range of frequency). This sharing of the communications medium may lead to collisions, which is where two or more communications devices attempt to transmit on the same channel simultaneously. Consequently, mechanisms are required to avoid collisions.

[0003] One known mechanism for dealing with collisions is known as a Distributed Coordination Function (DCF). A DCF works by requiring a communications device wishing to transmit to listen on the channel for a particular interval. If the channel is busy (e.g. another communications device is transmitting on the channel) the communications device defers attempting to access the channel for a "back-off period". The back-off period typically has a random element, so that communications devices do not synchronously defer access and then re-attempt access concurrently.

[0004] A particular working group of 802.1 1 is the 802.11 ah group. In that group several use cases were presented (see document IEEE 802.11-1 l/0457r0 entitled

POTENTIAL COMPROMISE FOR 802.1 1 AH USE CASE DOCUMENT by Rolf de Vegt, Qualcomm, March 2011). Specifically, in use case la Smart Grid - Meter to Pole it is expected that a single access point (AP) must support a large number of stations (STA), that can be possibly as high as 6000 stations. In this Smart Grid to Pole configuration the different stations report through the wireless medium different parameters of the electrical distribution system they sense. Since this use case pertains to a sensor deployment those STAs operate on a strict energy budget. In addition, providing energy efficient operations is not limited to the area of 802.1 lah, but would also be valuable for any type of network that contains devices that have limited battery power supplies, or even to reduce energy usage for network devices using any type of power supply. The communication devices that operate on a strict energy budget may include battery powered sensors which transmit and receive data very rarely and therefore stay in a low power operation mode for relatively long periods of time. In order to support such a large number of communication devices operating in the DCF mode, access points may utilize techniques to restrict the contention to the channel to avoid collisions of simultaneous transmissions in the collision domain. One such technique to reduce contention and collisions of transmission is a method that is configured to group communication devices into multiple groups and then to assign certain parameters for each group that would control the group's access to the channel. In one example, the group parameters may be such that 2 devices belong in 2 different groups may both access that channel at the same time but with a small probability. Alternatively, in another example, 2 devices that belong in 2 different groups may not access the channel at the same period of time; one device belonging in one group is prohibited from accessing the channel while the other device is allowed to contend like in the regular DCF mode of operation. The duration of channel access prohibition is another parameter of this grouping concept. A device that is prohibited access should eventually be allowed access and vice versa to guarantee that both devices can eventually access the channel.. Such grouping information and parameters for the operation can be delivered to the communication devices in an association phase or, for example, in broadcast information such as in a beacon frame.

[0005] However, communication devices may operate in low power mode for prolonged periods of time and therefore grouping related parameters may not be valid anymore when the communication device wakes up and resumes a channel access operation. Also, broadcast messages, such as beacons, are transmitted relatively sparsely and if a communication device stays in low power mode for extended periods of time it may lose the synchronization (e.g. due to the internal clock drift in the access point and in the communication device) and may not able to estimate when the next beacon or other broadcast message would be transmitted by the access point. Such behavior, for example, may cause the communication device to stay awake for a relatively long duration trying to receive a beacon transmission. In this regard, some embodiments of the current invention mitigate this by allowing a communication device to request and use grouping parameters without waiting for the receipt of a next beacon transmission.

BRIEF SUMMARY

[0006] In some example embodiments, a method is provided that comprises causing a transmission of a PS-Poll message, a modified PS-Poll message, or a newly defined group operation transmission message. The method of this embodiment may also include receiving a response message from an access point in response to the transmission of a PS-Poll message, a modified PS-Poll message, or a newly defined group operation transmission message, the response message configured to indicate grouping parameters used for communication devices. In some example embodiments, the grouping parameters are used to perform a contention test.

[0007] In further example embodiments, an apparatus is provided that includes at least one processor and at least one memory including computer program code with the at least one memory and the computer program code being configured, with the at least one processor, to cause the apparatus to at least cause a transmission of a PS-Poll message, a modified PS-Poll message, or a newly defined group operation transmission message. The at least one memory and computer program code may also be configured to, with the at least one processor, cause the apparatus to receive a response message from an access point in response to the transmission of a PS-Poll message, a modified PS-Poll message, or a newly defined group operation transmission message, the response message configured to indicate grouping parameters used for communication devices. In some example embodiments, the at least one memory and computer program code may also be configured to, with the at least one processor, cause the apparatus to perform a contention test using the received grouping parameters.

[0008] In yet further example embodiments, a computer program product may be provided that includes at least one non-transitory computer-readable storage medium having computer-readable program instructions stored therein with the computer-readable program instructions including program instructions configured to cause a transmission of a PS-Poll message, a modified PS-Poll message, or a newly defined group operation transmission message. The computer-readable program instructions may also include program instructions configured to receive a response message from an access point in response to the transmission of a PS-Poll message, a modified PS-Poll message, or a newly defined group operation transmission message, the response message configured to indicate grouping parameters used for communication devices. In some example embodiments, the computer-readable program instructions may also include program instructions configured to perform a contention test using the received grouping parameters.

[0009] In yet further example embodiments, an apparatus is provided that includes means for causing a transmission of a PS-Poll message, a modified PS-Poll message, or a newly defined group operation transmission message. The apparatus of this embodiment may also include means for receiving a response message from an access point in response to the transmission of a PS-Poll message, a modified PS-Poll message, or a newly defined group operation transmission message, the response message configured to indicate grouping parameters used for communication devices. The apparatus of this embodiment may also include means for performing a contention test using the received grouping parameters.

[0010] In some example embodiments, a method is provided that comprises receiving a transmission of a PS-Poll message, a modified PS-Poll message, or a newly defined group operation transmission message from a communication device. The method of this embodiment may also include causing a response message to be transmitted to the communication device, the response message configured to indicate grouping parameters used with the communication devices.

[0011] In further example embodiments, an apparatus is provided that includes at least one processor and at least one memory including computer program code with the at least one memory and the computer program code being configured, with the at least one processor, to cause the apparatus to at least receive a transmission of a PS-Poll message, a modified PS-Poll message, or a newly defined group operation transmission message from a communication device. The at least one memory and computer program code may also be configured to, with the at least one processor, cause the apparatus to cause a response message to be transmitted to the communication device, the response message configured to indicate grouping parameters used with the communication devices.

[0012] In yet further example embodiments, a computer program product may be provided that includes at least one non-transitory computer-readable storage medium having computer-readable program instructions stored therein with the computer-readable program instructions including program instructions configured to receive a transmission of a PS-Poll message, a modified PS-Poll message, or a newly defined group operation transmission message from a communication device. The computer-readable program instructions may also include program instructions configured to cause a response message to be transmitted to the communication device, the response message configured to indicate grouping parameters used with the communication devices.

[0013] In yet further example embodiments, an apparatus is provided that includes means for receiving a transmission of a PS-Poll message, a modified PS-Poll message, or a newly defined group operation transmission message from a communication device. The apparatus of this embodiment may also include means for causing a response message to be transmitted to the communication device, the response message configured to indicate grouping parameters used with the communication devices.

[0014] In some example embodiments, a method is provided that comprises causing a request for grouping parameters to be transmitted to an access point. In some example embodiments, the request may further indicate the current grouping parameters stored at the communication device. In some example embodiments, the access point is configured to transmit new grouping parameters in response to the request. In some example embodiments, the access point is configured to transmit new grouping parameters only if the grouping parameters included in the request are invalid.

[0015] In further example embodiments, an apparatus is provided that includes at least one processor and at least one memory including computer program code with the at least one memory and the computer program code being configured, with the at least one processor, to cause the apparatus to at least cause a request for grouping parameters to be transmitted to an access point. In some example embodiments, the request may further indicate the current grouping parameters stored at the communication device. In some example embodiments, the access point is configured to transmit new grouping parameters in response to the request. In some example embodiments, the access point is configured to transmit new grouping parameters only if the grouping parameters included in the request are invalid.

[0016] In yet further example embodiments, a computer program product may be provided that includes at least one non-transitory computer-readable storage medium having computer-readable program instructions stored therein with the computer-readable program instructions including program instructions configured to cause a request for grouping to be transmitted to an access point. In some example embodiments, the request may further indicate the current grouping parameters stored at the communication device. In some example embodiments, the access point is configured to transmit new grouping parameters in response to the request. In some example embodiments, the access point is configured to transmit new grouping parameters only if the grouping parameters included in the request are invalid.

[0017] In yet further example embodiments, an apparatus is provided that includes means for causing a request for grouping parameters to be transmitted to an access point. In some example embodiments, the request may further indicate the current grouping parameters at the communication device. In some example embodiments, the access point is configured to transmit new grouping parameters only if the grouping parameters included in the request are invalid.

[0018] In some example embodiments, a method is provided that comprises receiving a request for grouping parameters. In some example embodiments, the request may further indicate the current grouping parameters at the communication device. The method of this embodiment may include transmitting new grouping parameters. A method of some example embodiments may also include transmitting new grouping parameters if the grouping parameters included in the request are invalid. The method of this embodiment may also include transmitting an acknowledgement message if the transmitted grouping parameters are valid.

[0019] In further example embodiments, an apparatus is provided that includes at least one processor and at least one memory including computer program code with the at least one memory and the computer program code being configured, with the at least one processor, to cause the apparatus to at least receive a request for grouping parameters. In some example embodiments, the request may further indicate the current grouping parameters at the communication device. The at least one memory and computer program code may also be configured to, with the at least one processor, cause the apparatus to transmit new grouping parameters. The at least one memory and computer program code may also be configured to, with the at least one processor, cause the apparatus to transmit new grouping parameters if the grouping parameters included in the request are invalid. In some example embodiments, the at least one memory and computer program code may also be configured to, with the at least one processor, cause the apparatus to transmit an acknowledgement message if the transmitted grouping parameters are valid.

[0020] In yet further example embodiments, a computer program product may be provided that includes at least one non-transitory computer-readable storage medium having computer-readable program instructions stored therein with the computer-readable program instructions including program instructions configured to receive a request for grouping parameters. In some example embodiments, the request may further indicate the current grouping parameters at the communication device. The computer-readable program instructions may also include program instructions configured to transmit new grouping parameters. The at least one memory and computer program code may also be configured to, with the at least one processor, cause the apparatus to transmit new grouping parameters if the grouping parameters included in the request are invalid. In some example embodiments, the computer-readable program instructions may also include program instructions configured to transmit an acknowledgement message if the transmitted grouping parameters are valid.

[0021] In yet further example embodiments, an apparatus is provided, that includes means for receiving a request of grouping parameters. In some example embodiments, the request may further indicate the current grouping parameters at the communication device. The apparatus of this embodiment may also include means for transmitting new grouping parameters. The apparatus of this embodiment may also include means for transmitting new grouping parameters if the grouping parameters included in the request are invalid. In some example embodiments, the apparatus of this embodiment may also include means for transmitting an acknowledgement message if the transmitted grouping parameters are valid. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Having thus described the example embodiments of the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

[0023] Figure 1 is a schematic representation of a system having a communication device that may enable wireless data transmission and that may benefit from example embodiments of the present invention;

[0024] Figure 2 is a block diagram of an apparatus that may be embodied by a communication device and/or an access point in accordance with some example embodiments of the present invention;

[0025] Figures 3 is an example PS-Poll frame format;

[0026] Figure 4 is a flow chart illustrating further operations performed by an example communication device in accordance with some example embodiments of the present invention;

[0027] Figure 5 is a flow chart illustrating further operations performed by an example access point in accordance with some example embodiments of the present invention;

[0028] Figure 6 is a flow chart illustrating further operations for requesting grouping parameters performed by an example communication device operating in accordance with some example embodiments of the present invention;

[0029] Figure 7 is a flow chart illustrating further operations when requesting grouping parameters performed by an example access point operating in accordance with some example embodiments of the present invention;

[0030] Figure 8 is a flow chart illustrating further operations for requesting grouping parameters performed by an example communication device operating in accordance with some example embodiments of the present invention; and

[0031] Figure 9 is a flow chart illustrating further operations when requesting grouping parameters performed by an example access point operating in accordance with some example embodiments of the present invention. DETAILED DESCRIPTION

[0032] The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the inventions are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal

requirements. Like numbers refer to like elements throughout.

[0033] As used in this application, the term "circuitry" refers to all of the

following: (a)hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and (b) to combinations of circuits and

software (and/or firmware), such as (as applicable): (i) to a combination of

processor(s) or (ii) to portions of processor(s)/software (including digital signal processor(s)), software, and memory(ies) that work together to cause an

apparatus, such as a mobile phone or server, to perform various functions) and (c) to circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present.

[0034] This definition of "circuitry" applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term "circuitry" would also cover an implementation of merely a processor (or multiple processors) or portion of a processor and its (or their) accompanying software and/or firmware. The term "circuitry" would also cover, for example and if applicable to the particular claim element, a baseband integrated circuit or application specific integrated circuit for a mobile phone or a similar integrated circuit in server, a cellular network device, or other network device.

[0035] In some wireless communication system examples, for example with respect to IEEE 802.1 1 , an access point may be configured to buffer data frames in an instance in which a communication device is in a low power state, is asleep, and/or the like. In such cases, the access point may be configured to notify a communication device about the buffered frames by indicating the presence of the buffered frames in a TIM (traffic indication map). In some examples, the TIM is transmitted in a beacon message. Once the communication device enters a powered state and/or awakes, the communication device then can retrieve the buffered frames, for example by signaling the access point and receiving the buffered frames. The transmission of data may indicate to the access point that the communication device is in a powered state or is awake. In some examples, the communication device may cause a power save poll (PS-Poll) message to be transmitted. The PS-Poll is configured to indicate to the access point that the communication device is awake and ready to receive data.

[0036] In some examples and as described herein, a communication device may operate in a low power state for a large portion of the time, for example under 802.1 lah, which is incorporated by reference herein. An example battery powered communication device may transmit UL data relatively rarely, but may receive DL data even less. As such, between data transfers, it is beneficial for the battery powered communication devices to utilize the awake periods efficiently and enter low power state as fast as possible.

[0037] The systems and methods as described herein, in some example embodiments, are configured to cause a response message to be provided in response to a

communication device PS-Poll message, modified PS-Poll message, or newly defined group operation transmission message. As such an access point may be configured to respond to a communication device PS-Poll message, modified PS-Poll message, or newly defined group operation transmission message by causing a response message to be transmitted to the communication device. In some example embodiments, the response message may indicate to the communication device the grouping parameters. The communication device may, for example, use these grouping parameters to determine its new access parameters. In some example embodiments, the response message may include an indication of the duration until the next beacon is to be transmitted by the access point. In some example embodiments, the response message may include extended downlink (DL) buffer status information. In some example embodiments, the response message may include an indication of the time period in which DL data will be transmitted to the communication device.

[0038] In some example embodiments, the communication device may cause transmission of a PS-Poll message, a modified PS-Poll message, or a newly defined group operation transmission message that includes an indication that the communication device wants to receive new grouping parameters from the access point. In some example embodiments, the communication device may cause transmission of a message that includes interference levels observed by the communication device when it entered a powered up or awake mode.

[0039] Although the method, apparatus and computer program product as described herein may be implemented in a variety of different systems, one example of such a system is shown in Figure 1 , which includes a communication device (e.g.,

communication device 10) that is capable of communication via an access point 12, such as a base station, a macro cell, a Node B, an eNB, a coordination unit, a macro base station or other access point, with a network 14 (e.g., a core network). While the network may be configured in accordance with long term evolution (LTE™) or LTE-Advanced (LTE-A™), other networks may support the method, apparatus and computer program product of embodiments of the present invention including those configured in accordance with wideband code division multiple access (W-CDMA^{1 M}), CDMA2000, global system for mobile communications (GSM™), general packet radio service (GPRS™), IEEE™ 802.1 1 standard for wireless fidelity (WiFi), wireless local access network (WLAN™) Worldwide Interoperability for Microwave Access (WiMAX™) protocols, and/or the like.

[0040] The network 14 may include a collection of various different nodes, devices or functions that may be in communication with each other via corresponding wired and/or wireless interfaces. For example, the network may include one or more cells, including access point 12 and which may serve a respective coverage area. The access point 12 could be, for example, part of one or more cellular or mobile networks or public land mobile networks (PLMNs). In turn, other devices such as processing devices (e.g., personal computers, server computers or the like) may be coupled to the communication device 10 and/or other communication devices via the network.

[0041] A communication device, such as the communication device 10 (also known as a user equipment (UE), a mobile terminal or the like), may be in communication with other communication devices or other devices via the access point 12 and, in turn, the network 14. In some cases, the communication device 10 may include an antenna for transmitting signals to and for receiving signals from an access point 12.

[0042] In some example embodiments, the communication device 10 may be a mobile communication device such as, for example, a mobile telephone, portable digital assistant (PDA), pager, laptop computer, station (STA), or any of numerous other hand held or portable communication devices, computation devices, content generation devices, content consumption devices, or combinations thereof. However, as is described herein, the communication device 10 may also take the form of a communications enabled appliance, such as a thermostat configured to connect with an access point 12. Other such devices that are configured to connect to the network include, but are not limited to a refrigerator, a security system, a home lighting system, and/or the like.

Communication devices may also take the form of low power, battery operated sensors. As such, the communication device 10 may include one or more processors that may define processing circuitry and a processing system, either alone or in combination with one or more memories. The processing circuitry may utilize instructions stored in the memory to cause the communication device 10 to operate in a particular way or execute a specific functionality when the instructions are executed by the one or more processors. The communication device 10 may also include communication circuitry and

corresponding hardware/software to enable communication with other devices and/or the network 14.

[0043] In one embodiment, for example, the communication device 10 and/or the access point 12 may be embodied as or otherwise include an apparatus 20 as generically represented by the block diagram of Figure 2. While the apparatus 20 may be employed, for example, by a communication device 10 or an access point 12, it should be noted that the components, devices or elements described below may not be mandatory and thus some may be omitted in certain embodiments. Additionally, some embodiments may include further or different components, devices or elements beyond those shown and described herein.

[0044] As shown in Figure 2, the apparatus 20 may include or otherwise be in communication with processing circuitry 22 that is configurable to perform actions in accordance with example embodiments described herein. The processing circuitry may be configured to perform data processing, application execution and/or other processing and management services according to an example embodiment of the present invention. In some embodiments, the apparatus or the processing circuitry may be embodied as a chip or chip set. In other words, the apparatus or the processing circuitry may comprise one or more physical packages (e.g., chips) including materials, components and/or wires on a structural assembly (e.g., a baseboard). The structural assembly may provide physical strength, conservation of size, and/or limitation of electrical interaction for component circuitry included thereon. The apparatus or the processing circuitry may therefore, in some cases, be configured to implement an embodiment of the present invention on a single chip or as a single "system on a chip." As such, in some cases, a chip or chipset may constitute means for performing one or more operations for providing the functionalities described herein.

[0045] In an example embodiment, the processing circuitry 22 may include a processor 24 and memory 28 that may be in communication with or otherwise control a communication interface 26 and, in some cases, a user interface 29. As such, the processing circuitry may be embodied as a circuit chip (e.g., an integrated circuit chip) configured (e.g., with hardware, software or a combination of hardware and software) to perform operations described herein. However, in some embodiments taken in the context of the communication device 10, the processing circuitry may be embodied as a portion of a mobile computing device or other mobile terminal.

[0046] The user interface 29 (if implemented) may be in communication with the processing circuitry 22 to receive an indication of a user input at the user interface and/or to provide an audible, visual, mechanical or other output to the user. As such, the user interface may include, for example, a keyboard, a mouse, a trackball, a display, a touch screen, a microphone, a speaker, and/or other input/output mechanisms. The apparatus 20 need not always include a user interface. For example, in instances in which the apparatus is embodied as an access point 12, the apparatus may not include a user interface. As such, the user interface is shown in dashed lines in Figure 2.

[0047] The communication interface 26 may include one or more interface mechanisms for enabling communication with other devices and/or networks. In some cases, the communication interface may be any means such as a device or circuitry embodied in either hardware, or a combination of hardware and software that is configured to receive and/or transmit data from/to a network 14 and/or any other device or module in communication with the processing circuitry 22, such as between the communication device 10 and the access point 12. In this regard, the communication interface may include, for example, an antenna (or multiple antennas) and supporting hardware and/or software for enabling communications with a wireless communication network and/or a communication modem or other hardware/software for supporting communication via cable, digital subscriber line (DSL), universal serial bus (USB), Ethernet or other methods.

[0048] In an example embodiment, the memory 28 may include one or more non- transitory memory devices such as, for example, volatile and/or non-volatile memory that may be either fixed or removable. The memory may be configured to store information, data, applications, instructions or the like for enabling the apparatus 20 to carry out various functions in accordance with example embodiments of the present invention. For example, the memory could be configured to buffer input data for processing by the processor 24. Additionally or alternatively, the memory could be configured to store instructions for execution by the processor. As yet another alternative, the memory may include one of a plurality of databases that may store a variety of files, contents or data sets. Among the contents of the memory, applications may be stored for execution by the processor in order to carry out the functionality associated with each respective application. In some cases, the memory may be in communication with the processor via a bus for passing information among components of the apparatus.

[0049] The processor 24 may be embodied in a number of different ways. For example, the processor may be embodied as various processing means such as one or more of a microprocessor or other processing element, a coprocessor, a controller or various other computing or processing devices including integrated circuits such as, for example, an ASIC (application specific integrated circuit), an FPGA (field programmable gate array), or the like. In an example embodiment, the processor may be configured to execute instructions stored in the memory 28 or otherwise accessible to the processor. As such, whether configured by hardware or by a combination of hardware and software, the processor may represent an entity (e.g., physically embodied in circuitry - in the form of processing circuitry 22) capable of performing operations according to embodiments of the present invention while configured accordingly. Thus, for example, when the processor is embodied as an ASIC, FPGA or the like, the processor may be specifically configured hardware for conducting the operations described herein. Alternatively, as another example, when the processor is embodied as an executor of software instructions, the instructions may specifically configure the processor to perform the operations described herein.

[0050] In some example embodiments, a communication device is configured to indicate to an access point that the communication device is in a powered state or awake mode. A communication device 10, such as via the processing circuitry 22, the processor 24, the communications interface 26 or the like, may be configured to transmit a message to an access point, such as access point 12. Such a transmission may occur once the communication device enters a powered state or awake mode. Alternatively or additionally, the communications device 10, such as by the processing circuitry 22, the processor 24, the communication interface 26 or the like, may transmit a request to receive new grouping parameters, for example, via a request in a part of the medium access control (MAC) frame. In some example embodiments, the request to receive new grouping parameters may further indicate the grouping parameters that are currently known by the communication device 10.

[0051] Figure 3 is an example PS-Poll frame format. As is shown in with respect to Figure 6, the frame format may comprise a Frame Control indicating the type of frame in a subtype value field (e.g. a PS-Poll value). An AID field indicates the Association ID of the transmitting communication device. A BSSID (Basic Service Set ID) field indicates the receiver address (e.g. the access point). A TA field indicates the transmitter's MAC address. A FCS field indicates the frame check sequence for the PS-Poll MAC header.

[0052] In some example embodiments, the communication device 10, such as by the processing circuitry 22, the processor 24, the communication interface 26 or the like, may cause transmission of a newly introduced group operation message once the

communication device 10 enters a powered state or awake mode additionally, or alternatively, to causing transmission of a PS-Poll message or of a modified PS-Poll message. In the instances where the communication device 10 causes transmission of a group operation message or a modified PS-Poll message, the group operation message and the modified PS-Poll message include a request for operation related parameters from the access point 12 in a similar fashion to the PS-Poll message, as described herein.

[0053] Upon receipt of the message from the communication device, the access point 12, such as by the processing circuitry 22, the processor 24, the communication interface 26 or the like, may be configured to generate an response message and cause the response message to be transmitted to the communication device 10. The communication device 10, such as via the communication interface 26, may receive a response from the access point 12. The response message may be configured such that it indicates to the communication device 10, current grouping parameters. The response message may indicate the duration until the next beacon will be transmitted by the access point. The response message may indicate extended downlink (DL) buffer status information. In these instances, the DL buffer status information may indicate the amount of traffic, where the amount of traffic may be indicated by a traffic category (e.g. very little traffic, little traffic, moderate traffic, high traffic, very high traffic). The response message may indicate the time period in which DL data will be transmitted to the communication device.

[0054] In some example embodiments, the access point 12 may be configured to cause transmission of a response message in a specific management frame with a special subtype value, which may be indicated in the Frame Control Field as part of the medium access control (MAC) frame. In some example embodiments, the access point 12 may be configured to respond to a PS-Poll, a modified PS-Poll, or a group operation message received from a communication device by causing transmission of an immediate DATA, ACK, or response message. In some example embodiments, the access point 12 may be configured to multiplex the response message into the DL DATA frame.

[0055] The access point 12, such as by the processing circuitry 22, the processor 24, the communication interface 26, or the like may be configured to respond to the request for new grouping parameters indicated in the message transmitted from the

communication device. In some example embodiments, the access point 12 is configured to respond by causing transmission of a response message indicating the grouping parameters currently in use. In some example embodiments, the access point 12 is configured to respond with new grouping parameters only if the parameters known by the communication device 10 are obsolete. In these instances, if the parameters known by the communication device 10 are still valid, the access point 12 may be configured to send no response or cause an ACK message to be transmitted.

[0056] Alternatively or additionally, a communication device 10 can cause information regarding interference levels observed by the communication device 10 when it entered a powered up state or awake mode to be included with the request to receive new grouping parameters. In these instances, the access point 12 may be configured to adjust grouping parameters based on the interference level information provided by the communication device.

[0057] In some example embodiments, grouping parameters transmitted by the access point 12 may include the number of groups used for grouping the communication devices. In some example embodiments, the grouping parameters transmitted by the access point 12 may include a contention factor, Q_n, and a deferral period, T_n, for each of the plurality of groups. In some example embodiments, the grouping parameters transmitted by the access point 12 may include a validity period, π_η, indicating the duration for which the grouping parameters are valid. In some embodiments, the contention factor, Q_n, may take a value from the interval [0,1], although other intervals may be used. In some example embodiments, the above described grouping parameters may not all be included within a response message. In some example embodiments, a response message may also include additional grouping parameters.

[0058] In instances where the grouping parameters include a validity period, π_η, some example embodiments allow a communication device to use grouping parameters without receiving a beacon. In some example embodiments, the validity period allows a communication device to remain in a low power state or sleep mode if the

communication device is a member of a non-contending group. Additionally, or alternatively, in some example embodiments, the validity period, π_η, may allow a communication device to remain in a low power state or sleep mode and not listen for a next beacon if the validity period of the current grouping parameters for the

communication device has not expired and the communication device is a member of a non-contending group (e.g. if the validity period is longer than the duration period, the communication device may decide to remain in a low power state or sleep mode for the entire validity period).

[0059] In some example embodiments, the communication device 10 causes transmission of a PS-Poll frame that eliminates the use of the TA field within the PS-Poll frame to allow for reduced message size. In some example embodiments, the

communication device 10 causes transmission of a PS-Poll frame that replaces the TA field within the PS-Poll frame with data indicating a request for grouping parameters. In some example embodiments, the communication device 10 causes transmission of a PS- Poll frame that replaces the TA field within the PS-Poll frame with data indicating the current grouping parameters known to the communication device 10.

[0060] In some example embodiments, where the access point 12 is configured to cause transmission of a response message indicating extended DL buffer status information, the amount of traffic in the downlink can be indicated by categories (e.g. very little traffic, little traffic, moderate traffic, high traffic, very high traffic). In these instances, the granularity of the amount of traffic indication may be based on the number of bits available to provide the signaling. For example, if two bits are available, the traffic indication may be defined e.g., as 00: little traffic, 01 : moderate traffic, 10: high traffic, 1 1 : very high traffic. Alternatively, if a single bit is available, the traffic indication may be defined e.g., as 0: little traffic, 1 : high traffic.

[0061] The communication device 10, such as by the processing circuitry 22, the processor 24, the communication device 10 or the like, may determine whether it passes or fails a contention test using the contention factor, Q_n, and a deferral period, T_n, parameters of the group in which the communication device is a member. The communication device 10 if it has data in its buffer, may for example randomly and uniformly select a number r in the interval [0,1]. This interval is just one example, as other distributions may be used for selecting r. If r > Q_n, then the communication device 10 does not contend for the channel and the communication device enters a low power state or sleep mode for a period T_n. If r < Q_n, then the communication device 10 can contend for the channel according to DCF.

[0062] Figures 4-9 illustrate example operations performed by a method, apparatus, and computer program product, such as apparatus 20 of Figure 2 in accordance with one embodiment of the present invention. It will be understood that each block of the flowcharts, and combinations of blocks in the flowcharts, may be implemented by various means, such as hardware, firmware, processor, circuitry and/or other device associated with execution of software including one or more computer program instructions. For example, one or more of the procedures described above may be embodied by computer program instructions. In this regard, the computer program instructions which embody the procedures described above may be stored by a memory 28 of an apparatus employing an embodiment of the present invention and executed by a processor 24 in the apparatus. As will be appreciated, any such computer program instructions may be loaded onto a computer or other programmable apparatus (e.g. , hardware) to produce a machine, such that the resulting computer or other programmable apparatus provides for implementation of the functions specified in the flowcharts' block(s). These computer program instructions may also be stored in a non-transitory computer-readable storage memory that may direct a computer or other programmable apparatus to function in a particular manner, such that the instructions stored in the computer-readable storage memory produce an article of manufacture, the execution of which implements the function specified in the flowcharts' block(s). The computer program instructions may also be loaded onto a computer or other programmable apparatus to cause a series of operations to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide operations for implementing the functions specified in the flowcharts' block(s). As such, the operations of Figures 4-9, when executed, convert a computer or processing circuitry into a particular machine configured to perform an example embodiment of the present invention. Accordingly, the operations of Figures 4-9 define an algorithm for configuring a computer or processing circuitry 22, e.g., a processor, to perform an example embodiment. In some cases, a general purpose computer may be provided with an instance of the processor which performs the algorithm of Figures 4-9 to transform the general purpose computer into a particular machine configured to perform an example embodiment. [0063] Accordingly, blocks of the flowcharts support combinations of means for performing the specified functions and combinations of operations for performing the specified functions. It will also be understood that one or more blocks of the flowchart, and combinations of blocks in the flowcharts, can be implemented by special purpose hardware -based computer systems which perform the specified functions, or

combinations of special purpose hardware and computer instructions.

[0064] In some embodiments, certain ones of the operations above may be modified or further amplified as described below. Moreover, in some embodiments additional optional operations may also be included. It should be appreciated that each of the modifications, optional additions or amplifications below may be included with the operations above either alone or in combination with any others among the features described herein.

[0065] Figure 4 is a flow chart illustrating operations performed by an example communication device in accordance with some example embodiments of the present invention. As is shown with respect to operation 402, the apparatus 20 embodied, for example, by a communications device 10, may include means, such as the processing circuitry 22, the processor 24, the communication interface 26 or the like, for causing a PS-Poll frame transmission. The communications device 10 may include means, such as the processing circuitry 22, the processor 24, the communication interface 26 or the like, for causing a request for grouping parameters to be transmitted to the access point. In some example embodiments, the request for grouping parameters is indicated within PS- Poll frame.

[0066] As is shown with respect to operation 404, the apparatus 20 embodied, for example, by a communications device 10, may include means, such as the processing circuitry 22, the processor 24, or the like, for receiving grouping parameters from the access point. As is shown with respect to operation 406, the communications device 10, such as by the processing circuitry 22, the processor 24, or the like, may use the grouping parameters to perform a contention test if it has data in its buffer, to determine whether the communications device 10 may contend for the channel. If the communication device 10 passes the contention test, the communication device 10 proceeds to operation 408 and contends according to DCF. If the communication device 10 fails the contention test, the communication device 10 proceeds to operation 410 and returns to a low power state or sleep mode.

[0067] Figure 5 is a flow chart illustrating operations performed by an example access point in accordance with some example embodiments of the present invention. As is shown with respect to operation 502, the apparatus 20 embodied, for example, by an access point 12, may include means, such as the processing circuitry 22, the processor 24, the communication interface 26 or the like, for receiving a PS-Poll transmission, a modified PS-Poll transmission, or a newly defined group operation transmission from a communication device.

[0068] As is shown with respect to operation 504, the apparatus 20 embodied, for example, by an access point 12, may include means, such as the processing circuitry 22, the processor 24 or the like, for causing a response message to be generated, wherein the response message includes grouping parameters.

[0069] As is shown with respect to operation 506, the apparatus 20 embodied, for example, by an access point 12, may include means, such as the processing circuitry 22, the processor 24, the communication interface 26 or the like, for causing a response message to be transmitted to the communication device, the response message configured to indicate valid grouping parameters.

[0070] Figure 6 is a flow chart illustrating operations performed by an example communication device in accordance with some example embodiments of the present invention. As is shown with respect to operation 602, the apparatus 20 embodied, for example, by a communications device 10, may include means, such as the processing circuitry 22, the processor 24, the communication interface 26 or the like, for causing a request to receive new grouping parameters to be transmitted to an access point. As is shown with respect to operation 604, the apparatus 20 embodied, for example, by a communications device 10, may include means, such as the processing circuitry 22, the processor 24, the communication interface 26 or the like, for receiving an indication that the existing grouping parameters were invalid and receiving new grouping parameters in response to the request. As is shown with respect to operation 606, the communications device 10, such as by the processing circuitry 22, the processor 24, or the like, may use the grouping parameters to perform a contention test to determine whether the communications device 10 may contend for the channel in case the device has data in its buffer. If the communication device 10 passes the contention test, the communication device 10 proceeds to operation 608 and contends according to DCF. If the

communication device 10 fails the contention test, the communication device 10 proceeds to operation 610 and returns to a low power state or sleep mode. As is shown with respect to operation 612, the apparatus 20 embodied, for example, by a communications device 10, may include means, such as the processing circuitry 22, the processor 24, the communication interface 26 or the like, for receiving an indication that the existing grouping parameters are valid in response to the request. The communication device 10 then proceeds to operation 606 and uses the existing grouping parameters to perform a contention test to determine whether the communications device 10 may contend for the channel in case the device has data in its buffer.

[0071] Figure 7 is a flow chart illustrating operations performed by an example access point in accordance with some example embodiments of the present invention. As is shown with respect to operation 702, the apparatus 20 embodied, for example, by an access point 12, may include means, such as the processing circuitry 22, the processor 24, the communication interface 26 or the like, for receiving a request for grouping parameters from a communication device.

[0072] As is shown with respect to operation 704, the apparatus 20 embodied, for example, by an access point 12, may include means, such as the processing circuitry 22, the processor 24, the communication interface 26 or the like, for determining whether the grouping parameters included within the request are currently valid. If the received grouping parameters are still valid, the apparatus 20 embodied, for example, by an access point 12, may include means, such as the processing circuitry 22, the processor 24, the communication interface 26 or the like, for causing an acknowledgment message to be transmitted to the communication device at operation 706. In an alternative embodiment, the access point 12 may not transmit any response if the grouping parameters included within the request are currently valid. If the received grouping parameters are no longer valid, the apparatus 20 embodied, for example, by an access point 12, may include means, such as the processing circuitry 22, the processor 24, the communication interface 26 or the like, for causing a response message to be transmitted to the communication device indicating the new grouping parameters at operation 708.

[0073] Figure 8 is a flow chart illustrating operations performed by an example communication device in accordance with some example embodiments of the present invention. As is shown with respect to operation 802, the apparatus 20 embodied, for example, by a communications device 10, may include means, such as the processing circuitry 22, the processor 24, the communication interface 26 or the like, for causing a request to receive new grouping parameters to be transmitted to an access point. As is shown with respect to operation 804, the apparatus 20 embodied, for example, by a communications device 10, may include means, such as the processing circuitry 22, the processor 24, the communication interface 26 or the like, for receiving new grouping parameters in response to the request. As is shown with respect to operation 806, the communications device 10, such as by the processing circuitry 22, the processor 24, or the like, may use the grouping parameters to perform a contention test to determine whether the communications device 10 may contend for the channel in case the device has data in its buffer. If the communication device 10 passes the contention test, the communication device 10 proceeds to operation 808 and contends according to DCF. If the communication device 10 fails the contention test, the communication device 10 proceeds to operation 810 and returns to a low power state or sleep mode.

[0074] Figure 9 is a flow chart illustrating operations performed by an example access point in accordance with some example embodiments of the present invention. As is shown with respect to operation 902, the apparatus 20 embodied, for example, by an access point 12, may include means, such as the processing circuitry 22, the processor 24, the communication interface 26 or the like, for receiving a request for grouping parameters from a communication device.

[0075] As is shown with respect to operation 904, the apparatus 20 embodied, for example, by an access point 12, may include means, such as the processing circuitry 22, the processor 24, the communication interface 26 or the like, for causing a response message to be transmitted to the communication device indicating the new grouping parameters. [0076] Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, although the foregoing descriptions and the associated drawings describe example embodiments in the context of certain example combinations of elements and/or functions, it should be appreciated that different combinations of elements and/or functions may be provided by alternative embodiments without departing from the scope of the appended claims. In this regard, for example, different combinations of elements and/or functions than those explicitly described above are also contemplated as may be set forth in some of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

WHAT IS CLAIMED IS:

1. A method comprising:

causing a message transmission indicating a powered state;

receiving a response message from an access point in response to the message transmission, the response message configured to include current grouping parameters from the access point; and

performing a test based on the current grouping parameters, wherein the test indicates whether a communication device should contend for a channel.

2. A method according to Claim 1, further comprising:

causing a powered state to be maintained in an instance in which the test result indicates that a communication device may contend; and

causing a transition to a low power state in an instance in which the test result does not indicate that a communication device may contend.

3. A method according to Claim 1 , wherein the response message comprises one or more of:

one or more grouping parameters to be used by the communication device; a duration until a next beacon will be transmitted by the access point; a downlink buffer status; and

a time period in which downlink data will be transmitted from the access point.

4. A method according to Claim 3, wherein the downlink buffer status comprises an indication of an amount of traffic in a downlink.

5. A method according to Claim 4, wherein the indication of an amount of traffic in a downlink comprises a characterization of the amount of traffic by the access point, wherein the characterization depends on the number of bytes of data available at the access point for the communication device.

6. A method according to Claim 5, wherein the granularity of the characterizations that are used to characterize the amount of traffic is defined by a number of bits used in the indication of an amount of traffic in a downlink.

7. A method according to Claim 1 , wherein grouping parameters comprises one or more of:

a count of a plurality of groups defined by the access point;

a contention factor for each one of the plurality of groups;

a deferral period for each one of the plurality of groups; and

a validity period for each one of the plurality of groups.

8. A method according to Claim 1 , wherein the response message comprises a specific management frame with a special subtype which is indicated in a Frame Control field.

9. A method according to Claim 1 , wherein the response message is multiplexed in the downlink DATA frame.

10. A method comprising:

causing transmission of a message requesting grouping parameters, the request message configured to include stored grouping parameters;

receiving a response message from an access point in response to the request message transmission if the stored grouping parameters are invalid, the response message configured to include current grouping parameters from the access point; and performing a test based on the current grouping parameters, wherein the test indicates whether a communication device should contend for a channel.

11. A method according to Claim 10, the method further comprising receiving an acknowledgement message transmission from the access point if the stored grouping parameters are valid.

12. A method according to Claim 10, the method further comprising receiving no response message transmission from the access point if the stored grouping parameters are valid.

13. An apparatus comprising:

at least one processor; and

at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to at least:

cause a message transmission indicating a powered state;

perform a test based on the current grouping parameters, wherein the test indicates whether a communication device should contend for a channel.

14. An apparatus according to Claim 13, wherein the at least one memory including the computer program code is further configured to, with the at least one processor, cause the apparatus to:

cause a powered state to be maintained in an instance in which the test result indicates that a communication device may contend; and cause a transition to a low power state in an instance in which the test result does not indicate that a communication device may contend.

15. An apparatus according to Claim 13, wherein the response message comprises one or more of:

a time period in which downlink data will be transmitted from the access point.

16. An apparatus according to Claim 15, wherein the downlink buffer status comprises an indication of an amount of traffic in a downlink.

17. An apparatus according to Claim 16, wherein the indication of an amount of traffic in a downlink comprises a characterization of the amount of traffic by the access point, wherein the characterization depends on the number of bytes of data available at the access point for the communication device.

18. An apparatus according to Claim 17, wherein the granularity of the characterizations that are used to characterize the amount of traffic is defined by a number of bits used in the indication of an amount of traffic in a downlink.

19. An apparatus according to Claim 13, wherein grouping parameters comprises one or more of:

a count of a plurality of groups defined by the access point;

a contention factor for each one of the plurality of groups;

a deferral period for each one of the plurality of groups; and

a validity period for each one of the plurality of groups.

20. An apparatus according to Claim 13, wherein the response message comprises a specific management frame with a special subtype which is indicated in a Frame Control field.

21 . An apparatus according to Claim 13, wherein the response message is multiplexed in the downlink DATA frame.

22. An apparatus comprising:

at least one processor; and

cause transmission of a message requesting grouping parameters, the request message configured to include stored grouping parameters; receive a response message from an access point in response to the request message transmission if the stored grouping parameters are invalid, the response message configured to include current grouping parameters from the access point; and perform a test based on the current grouping parameters, wherein the test indicates whether a communication device should contend for a channel.

23. An apparatus according to Claim 22, the apparatus further comprising receiving an acknowledgement message transmission from the access point if the stored grouping parameters are valid.

24. An apparatus according to Claim 22, the apparatus further comprising receiving no response message transmission from the access point if the stored grouping parameters are valid.

25. A computer program product comprising:

at least one computer readable non-transitory memory medium having program code stored thereon, the program code which when executed by an apparatus cause the apparatus at least to:

cause a message transmission indicating a powered state;

26. A computer program product according to Claim 25, wherein the at least one memory including the computer program code is further configured to, with the at least one processor, cause the apparatus to:

cause a powered state to be maintained in an instance in which the test result indicates that a communication device may contend; and

cause a transition to a low power state in an instance in which the test result does not indicate that a communication device may contend.

27. A computer program product according to Claim 25, wherein the response message comprises one or more of:

a time period in which downlink data will be transmitted from the access point.

28. A computer program product according to Claim 27, wherein the downlink buffer status comprises an indication of an amount of traffic in a downlink.

29. A computer program product according to Claim 28, wherein the indication of an amount of traffic in a downlink comprises a characterization of the amount of traffic by the access point, wherein the characterization depends on the number of bytes of data available at the access point for the communication device.

30. A computer program product according to Claim 29, wherein the granularity of the characterizations that are used to characterize the amount of traffic is defined by a number of bits used in the indication of an amount of traffic in a downlink.

31 . A computer program product according to Claim 25, wherein grouping parameters comprises one or more of:

a count of a plurality of groups defined by the access point;

a contention factor for each one of the plurality of groups;

a deferral period for each one of the plurality of groups; and

a validity period for each one of the plurality of groups.

32. A computer program product according to Claim 25, wherein the response message comprises a specific management frame with a special subtype which is indicated in a Frame Control field.

33. A computer program product according to Claim 25, wherein the response message is multiplexed in the downlink DATA frame.

34. A computer program product comprising:

at least one computer readable non-transitory memory medium having program code stored thereon, the program code which when executed by an apparatus cause the apparatus at least to: cause transmission of a message requesting grouping parameters, the request message configured to include stored grouping parameters; receive a response message from an access point in response to the request message transmission if the stored grouping parameters are invalid, the response message configured to include current grouping parameters from the access point; and perform a test based on the current grouping parameters, wherein the test indicates whether a communication device should contend for a channel.

35. A computer program product according to Claim 34, further comprising program code instructions configured to receive an acknowledgement message transmission from the access point if the stored grouping parameters are valid.

36. A computer program product according to Claim 34, further comprising program code instructions configured to receive no response message transmission from the access point if the stored grouping parameters are valid.