Invented by Mohammed Sammour, Sudheer A. Grandhi, Arty Chandra, InterDigital Technology Corp
The InterDigital Technology Corp invention works as followsA method and apparatus can be used to assign groups of stations for wireless communications into one or more group. An access point (AP), based on the information from a station, may assign groups. Each station may receive group information and the group identifier can be displayed in a frame. The group information can be used to enhance performance, such as power savings, if the station is not part of the group.
Background for Methods and apparatus for efficient addressing in wireless communication
Frame aggregation” and “frame bursting” are two mechanisms proposed to improve the performance of WLAN Systems. These mechanisms are being considered for the 802.11n expansion to the 802.11 standard WLAN, which will enable higher throughput devices. “Both TGnSync proposals and WWISE proposals consider various frame aggregation schemes and frame bursting strategies.
FIG. “FIG. The difference between aggregation schemes is based on the parts of a package they aggregate.
MSDU Aggregation (100)” aggregates one or multiple medium access control (MAC), service data units (MSDUs), 102 into an aggregated MSDU, (A-MSDU), 104 with each MSDU being separated by a header subframe 106. A MAC header (108 ) is added to A-MSDU in order to create a single MAC protocol unit (MPDU).
MPDU Aggregation (120)” aggregates multiple MPDUs (122), with each MPDU being separated by a MPDU delimiter (126). The A-MPDU is then added with a physical header (PHY), including legacy training and signal fields 130 and HT Training SIGNAL fields 132.
PPDU Aggregation (140)” aggregates one or multiple PPDUs, with each PPDU having a PHY header and an MPDU. “A PHY header (148), including a legacy Training and SIGNAL fields 150 and HT training and SIGNAL fields 152, are added to create a single aggregated A-PPDU (154).
PPDU Bursting” (160), or high-throughput burst transmission (HTP), is the process of transmitting a series of frames 162 from a high-throughput station to a single medium-access. Each frame 162 has a PHY header (164), a legacy SIGNAL and training field (166), and a HT SIGNAL and training field 168. It also includes an MPDU (170). The frames 162 can be transmitted with an A-PPDU or reduced interframe spacing (RIFS), 172, to improve medium efficiency.
Aggregation and bursting schemes” can aggregate frames for a single receiver, (i.e. a WLAN destination), multiple receivers, (i.e. multiple WLAN destinations) or both. MRA stands for Multiple Receiver Aggregation. SRA stands for Single Receiver Aggregation. The MSDU aggregation is used as an example for SRA, since it only contains one MAC header that can identify a WLAN receiver address. The MPDU aggregation scheme, PPDU aggregation and PPDU bursting scheme can be used either for SRA or to MRA since each MPDU in the aggregate or the burst has a MAC header that can identify a unique WLAN receiver address.
Frame-aggregation and burst schemes increase the overall efficiency of the WLAN system. The majority of aggregation/bursting schemes do not support/support the battery/power saving issue. The duration of an aggregated burst or frame can be very long. If the WLAN destination addresses of the STAs are not known in advance, each STA will need to decode and receive the entire aggregated burst or frame to determine if it contains data for the STA.
The act of decoding and receiving the information from such long packets uses a lot of energy. Significant power/battery saving can be achieved by the receiving STA if they know that the aggregated frame/burst is not intended for them.
By providing information upfront about which STAs contain data in the aggregated burst or frame, STAs who do not possess data can save power by sleeping, i.e. not listening or decoding the entire packet, during the aggregated burst or frame. STAs with data in the aggregated burst or frame may also be able save power if they are given more information upfront. This upfront information relates to the timing of transmission of STA data in the aggregated burst or frame. This STA will use the timing information upfront to awaken (listen and decode), during the portions of the aggregated burst or frame that contain its data and sleep during other portions.
In the prior art there are proposals that support energy/battery saving. As shown in FIG. The TGnSync A-MPDU aggregation proposal 200 proposes to use an MRAD (Multiple Receiver Accumulated Descriptor) for the first MPDU in an aggregated frame. The PPDU 202 contains a PHY header 204, and an AMPDU 206. The PHY header includes an legacy training and SIGNAL area 208, and a HT Training and Signal field 210. The A-MPDU includes an MRAD 212 MPDU and a number of MPDUs (214), each separated by an “MPDU delimiter” 216.
The MRAD MPDU is used as follows. The MRAD MPDU is used in the following way. A STA without data will decode and receive up to the end MRAD MPDU. If the STA discovers that the MRAD does not include its receiver address, it may disable its receiver until the end aggregated frame. Since TGnSync mandates that MPDUs destined for the same recipient address must be contiguous within the AMPDU, a STA with data in the aggregated frames will receive and decode until it receives its MPDUs, and detects a new receiver address within the next MPDU. At that point, it can disable its receiver until the end the aggregatedframe.
The MRAD Mechanism is suitable for Single-Rate MRA Aggregation but not for Multiple-Rate MRA, where the aggregated MPDUs are sent in different rates, for PPDU aggregation or for PPDU bursting.
One proposal describes the Multiple-rate Multiple Receiver Accumulation (or Multiple MCS), which is a way to achieve power savings when using Multiple-rate MRA. This proposal calls for the use of an MMRAD, or MMRA Descriptor, which contains data on STA IDs, i.e. receiver addresses, as well as timing off information that can be used to save power. The MMRAD (MMRA Descriptor) is defined in the MAC portion and a single bit is used within the PHY section of the frame to indicate its presence.
The prior art proposals have many shortcomings, including: the MRAD and MMRAD are large and inefficient; it’s a variable-length field and the implementation can be simplified using only a packet of fixed length. The power-saving information also cannot be embedded in the PHY layer, which should maintain a small size. The power saving information is sent on the MAC layer, which is not robust enough because MRADs are sent at a speed that may not be decoded by all STAs. This is also a MAC-MPDU. If it is lost, or if a STA is unable to decode it properly, there will be no power savings. The timing information is also not given in an efficient way. “The current proposals are mainly aimed at A-MPDU aggregation and can’t efficiently and robustly be used with A-PPDU aggregation or reverse-direction traffic.
A method and device may be applicable to frame-aggregation schemes and frame-bursting schemes as well as to frames that have not been aggregated (e.g., those sent only to one receiver, for example).” The method and apparatus are not limited to battery and power savings. They can also be used in other performance-enhancing ways, such as addressing scalability through simplified group addressing or in packet scheduler implementation or design.
A method and device may be used to assign STAs to wireless communication groups. An access point (AP), based on the information received from a STA, may assign groups. Each STA may receive group information and the group identifier can be displayed in a frame.
A method and apparatus for enabling energy savings in wireless communication may assign STAs within a system to a number groups. Each STA may receive group information and the group identifier can be displayed in a frame. “A STA can enter power saving mode if it determines that it’s not a part of the group.
A method or apparatus for enabling energy savings in wireless communication may indicate the traffic direction in a picture frame. The frame destination may be indicated by the traffic direction. The STA can enter a power-saving mode if the traffic isn’t directed at the STA.
The method and apparatus can be used to decode and receive a frame in a STA, until the STA has decoded a power-saving indicator. The STA can enter a power-saving mode if the power-saving indicator indicates the STA is allowed to use this mode. The power saving icon may be linked to group information.
The method and apparatus can be used to send timing information to an STA within a portion or frame. On the basis of the timing information, the STA can enter a power-saving mode. The STA can exit the power-saving mode based upon the timing information. It may also receive and decode part of the frame once it exits the power-saving mode.Click here to view the patent on Google Patents.