EP1751921A1

EP1751921A1 - Superframe protocol packet data unit format having multirate packet aggregation for wireless systems

Info

Publication number: EP1751921A1
Application number: EP05736226A
Authority: EP
Inventors: Pen C. Li; Parag Garg; Monisha Ghosh
Original assignee: Koninklijke Philips Electronics NV
Current assignee: Koninklijke Philips NV
Priority date: 2004-05-13
Filing date: 2005-05-12
Publication date: 2007-02-14
Also published as: WO2005112354A9; JP2007537654A; WO2005112354A1

Abstract

A superframe, method and system for transmission of an aggregation of packets at multiple rates includes a header (300) comprising a preamble (305) and a PHY layer convergence protocol (310), a plurality of MAC management protocol data units (205), a beacon; and a super protocol service data unit header (315). A plurality of multi-rate aggregated packets (327) is grouped together in the superframe to provide power savings for the receiving nodes that can receive the packets in a reduced number of transmissions. Grouping the packets according to the MAC destinations also provides for shortening reception times by the nodes, resulting in power savings. The superframe permits the MAC service data units to be delivered to each of the nodes, resulting in power savings. The superframe permits the MAC service data units to be delivered to each of the nodes at different PHY rates to maximize efficiency.

Description

SUPERFRAME PROTOCOL PACKET DATA UNIT FORMAT HAVING MULTIRATE PACKET AGGREGATION FOR WIRELESS SYSTEMS

The present invention relates to apparatuses and processes designed for use with a form of data transmission using a superframe having a plurality of packets. More particularly, the present invention relates to an improvement in multiple receiver aggregation (MRA) data rate transmission and power savings.

The physical layer of current wireless systems, such as LANs that operate under access protocols such as IEEE 802.11, has several different options for modulation and coding. The selection of these options is normally determined by the maximum data rate given that the pack error rate is smaller than a given threshold. For example, the current Task Group N of IEEE Specification of 802.11 is developing new

Physical (PHY) and Medium Access Control (MAC) specifications for high data rate WLANs. Several industry consortia are currently preparing proposals for Task Group N, among them the industry consortium TGn Sync. The current specification of TGn Sync does not allow for different rates in multiple receiver aggregation. For example, the furthest receiver typically may have the slowest throughput, which can cause significant delays for other nodes/stations seeking to transmit or receive data, which in turn increases drain of power. Accordingly, there is a need in the art to provide packet aggregation to enable reception by different users at different PHY rates. However, this need must be addressed for proper consideration of

Quality-of-Service (QoS) parameters that include not just bandwidth (throughput) but delay, delay jitter and packet loss rates. The presently claimed invention provides a method, system and apparatus for providing a number of MAC Protocol Data Units MPDUs to a group of different receivers and linking them together to form a Super protocol data service unit (PDSU). This Super PDSU is encapsulated in a Super Protocol Packet Data Unit (PPDU) header in order to be delivered to the different stations. The scheme supports delivery of the individual MPDUs at different PHY rates with a potential of executing an efficient power-saving scheme at the receiver device.

Fig. 1 illustrates a system having a plurality of stations and their different PHY transmission rates. Fig. 2 illustrates criteria for forming a superframe format having packet aggregation. Fig. 3A illustrates a header showing one way that a superframe can be arranged according to the present invention. Fig. 3B illustrates the Super PDSU header portion of the superframe header shown in Fig. 3 A. Fig. 4 illustrates an arrangement of the Super PDSU header that is adapted to increase the efficiency of the receipt of fragmented MSDU transmission. Fig. 5 is an illustration of how an example of a Super PPDU provides power savings to several stations. Fig. 6 is one example of a PPDU frame structure. Fig. 7 illustrates one view structure of the aggregation information in accordance with Fig. 6. Fig. 8 illustrates another view of the aggregation information in accordance with an aspect of the invention. Fig. 9 illustrates active/sleep phases in accordance with an aspect of the invention. Fig. 10 illustrates another variation of the structure of aggregation information in accordance with another aspect of the invention. Fig. 11 illustrates yet another variation of the structure of aggregation information in accordance with another aspect of the invention. Fig. 12 illustrates active/sleep phases in accordance with the aggregation information shown in Figs. 10 and 11. Fig. 13 illustrates still another variation of the structure of aggregation information in accordance with another aspect of the invention. Fig. 14 illustrates active/sleep phases in accordance with the aggregation information shown in Fig. 13. Fig. 15 illustrates still another variation of the structure of aggregation information in accordance with another aspect of the invention. Fig. 16 illustrates active/sleep phases in accordance with the aggregation information shown in Fig. 15.

It is to be understood by persons of ordinary skill in the art that the following descriptions are provided for purposes of illustration, not for limitation. An artisan understands that there are many variations that lie within the spirit of the invention and the scope of the appended claims. Unnecessary detail of known functions and operations may be omitted from the current description so as not to obscure the finer points of the present invention. Fig 1 illustrates one typical example of a system for transmission of multi-rate aggregated packets according to the present invention. Again, it is stressed that a typical system would be far more complex than shown and may include a plethora of different devices communicating in a wired or wireless fashion.

The system shown in Fig. 1 includes a plurality of nodes 112, 113, 114 and a station 115. At least one of the plurality of nodes is adapted for receiving a superframe 125 comprising an aggregation of packets according to the present invention. In addition, one node 114 of the plurality of nodes 112, 113, and 114 may have a different PHY rate of transmission than the other nodes. It is also to be noted that at least one (typically more) of the plurality of nodes 112, 113, and 114 are adapted for receiving the superframe 125 comprising an aggregation of packets at different transmission rates 127, 128, and 129. Thus, a series of different nodes with different transmission rates can use the superframe according to the present invention at rates that maximize their efficiency. Moreover, it should be noted that at least one of the plurality of nodes 112, 113, and 114 may comprise a legacy device 112 that transmits and receives non-aggregated packet frames according to medium access control (MAC) protocols. Fig. 2 illustrates the criteria for forming a superframe format for packet aggregation according to the present invention. At the MAC layer 205, it is shown that a number of MPDUs may be grouped together if the delay bound by each individual MPDU can be met. In addition, it should be noted that a beacon can be grouped along with the group-addressed frames following the same at DTIM intervals. At the PHY level 210 the Super PSDU is shown, which is then aggregated into a Super PPDU. It should be noted that the Super PPDU should not infringe on the TBTT time and a link adaptation algorithm may set a limit on the length of the Super PPDU. The PDSUs that have a common device destination can be arranged adjacent to each other in the

Super PPDU in order to improve the power savings at the receiver. The PDSU contains the MAC service data unit (MSDU) that has the 802.11 MAC header and the payload. The receiver address (RA) in the MAC header is the same MAC address as the one that appears in the "MAC addr" field of the Super

PDSU header. The present invention includes a plurality of variations of the Super PPDU. For example, Fig. 3 A illustrates a header of the Super Frame according to an aspect of the present invention. The preamble 305 is a normal 802.11a PLCP (physical layer convergence protocol) preamble with 12 symbols. The PLCP header 310 also has a parameter used to signify that the following frame is not a normal PDSU. The rate bits, or the reserved bits, can be used for this purpose. The PLCP header that follows is a normal 802.1 la PLCP header. Each PLCP header except the one for the first PDSU is preceded by a preamble that may be used by the receiving station to synchronize. Fig. 3B is an illustration according to an aspect of the present invention that illustrates just the Super PDSU header 315 shown in Fig. 3 A. Here, the MAC address 320, preamble type, data rate 330, length 335 are shown. These aforementioned fields for each of the PSDUs are sufficient for each station to calculate when it could start receiving data and for how long such receiving may occur. The preamble type 325 field for the first MPDU may be ignored. The station can then decide to execute a power-saving scheme when it does not have to receive any data. A Super Duration ID field (not shown) may precede the tuple for the first station. This field can be then used by the stations for the virtual carrier sense mechanism, and will obviate any such calculation at all the receivers. According to this first aspect of the present invention, the beacon can be a part of the Superframe with a restriction that it will be the first PDS of the Super PSDU headers 315. The reason for the restriction is to meet the TBTT time before each beacon. If there are any power-saving stations in the basic service set, then the group addressed PSDUs will follow the Description Time-stamped beacon. In addition, in accordance with this first aspect of the present invention, the stations will decode the timing (TIM) element in the beacon and respond with a power saving (PS) polling packet. An access point (AP) will receive a plurality of polls within a beacon interval and aggregate the MSDU for those power-saving stations. In addition, according to this first aspect of the invention, there are times when the individual

MSDU requires an acknowledgement. In such cases, the Data-ACK sequence must take place during the duration of the Super PPDU (i.e. superframe). At the end of the transmission of the PSDU, the receiver, after a short interframe space, will transmit the acknowledgement. The preamble for a PSDU2 starts subsequent to the acknowledgement of the short interframe space. In case that the acknowledgement is not received for the first MPDU1, then the PHY makes a note of it and, after trying all the PSDUs, informs the status of each PSDU to the MAC layer. The MAC layer may then decide to retransmit that particular MPDU or may just discard it. It should be noted that according to the present invention, the PHY takes care of the acknowledgment reception at the transmitter of the Super PPDU. In addition, the PHY maintains a record of unsuccessful PSDUs. With regard to the aforementioned paragraph, the present invention also can support fragmentation of the MSDUs. However, with a simple 4-element tuple scheme for the PSDU header, a drawback would be that there will have to be a tuple for each fragment in the Super PSDU header. The format of the Super PSDU header may be changed in order to make more efficient use of the medium in case of fragmented MSDU transmission. Fig. 4 shows an arrangement of the Super PSDU header that is adapted to increase fragmented

MSDU transmission. In addition, it should be noted that this protocol is also valid for group-addressed frames as well. Whenever a station notices a group address in the Super PPDU header it determines whether it is a member of the group. If the station determines that it is a member of the group, it prepares to receive the frame as any other frame. Otherwise it just ignores the frame. Fig. 5 is an illustration of how an example of a Super PPDU according to the present invention provides efficient power at the station devices. As shown in Fig. 5 the PHY activity for stations 1-4 is curtailed as the stations all read the preamble 501, the PHY layer convergence protocol 503 and the Super

PSDU header 505. The nodes/station device can then go into a power-saving sleep mode, as shown by the low logic levels. According to the present invention, backward compatibility is maintained by an existing legacy device, which continues to transmit and receive using standard MAC protocols. This means that if a device transmits a non-Super PDSU, the rules of the virtual carrier sense apply according to standard MAC protocols. In addition, there are the second through the seventh aspects of the present invention that may refer to an 802.1 In header structure that is different from 802.11a, but is backwards-compatible in the sense that legacy 802.11 and 802.1 le stations can extract all information that is necessary for performing the carrier sense and backoff mechanism. Fig. 6 illustrates a potential PPDU format for 802.1 In as discussed by the consortium TGn Sync. The Legacy Short Training Field (L-STF), Legacy Long Training Field (L-LTF) and Legacy Signal field (L-SIG) are there for backwards compatibility with legacy 802.11 stations. In case of a 40 MHz transmission, the fields are transmitted with a bandwidth of 20 MHz on both halves of the 40 MHz ^' channel, whereby the fields on one half are phase-rotated with respect to the other half. The legacy fields are followed by a High Throughput Signal Field (HT-SIG), a High Throughput Short Training Field (HT- STF) and a number of High Throughput Long Training Fields (HT-LTF). The number of HT-LTFs is equal to the number of antennas. The different fields are not described in detail in this invention and only serve as an example of how the structure of the PHY header might look. The PHY header is followed by the PSDU-DATA. According to the present invention, the information on the structure of an aggregate is partly contained in the PHY header and partly inside the PSDU-DATA. The various aspects of the invention may differ in the way the information is distributed in-between the PHY header and the PSDU-DATA, and how the information is structured. For all aspects of the invention it is assumed that inside the PHY header the information is included inside the HT-SIG or similar field. As other information is included in the HT-SIG field beside the aggregation information, the part including the aggregation information is referred to as HT-SIG2 in the following. A second aspect of the present invention is now described. One difference between the second aspect of the invention and the first aspect is in the definition of the Super PPDU fields. Fig. 7 shows the structure of the HT-SIG2 705 and PSDU-DATA 755 in the case of the second aspect of the invention for an exemplary group of five stations, two of which are transmitting at Modulation/Coding Scheme (MCS) 1, two others at MCS2 and a third one at a different MCS3. It is assumed for simplicity in this example that each station is sending just one MPDU. Transmission of multiple MPDUs per station is obviously possible. According to the second aspect the HT-SIG2 contains the following aggregation information for each of the stations STAs: • Receiver (STAs) MAC address • MCS of this MPDU • PDU Length. Such a set of three fields is called a "tuple" because of the following: The MPDUs, each consists of MAC header and payload. The Receiver Address (RA) in the MAC header is the same MAC address as the one that appears in the 'MAC Addr' field of the HT-SIG2. The Preambles 715,725,735,745 following the MPDUs are used by the receiving station to synchronize and demap the following MPDU at the desired data rate (indicated in HT-SIG2/ MCS Field). With this second aspect of the invention there are multiple tuples that may contain the same MAC address. Multiple tuples having the same MAC address result in a particular device receiving multiple MPDUs in this aggregate PSDU 775. The MPDUs destined to one device may be further arranged adjacent each other in order to improve the power-savings at the receiver. As shown in Fig. 8, a third aspect of the present invention differs from the second aspect of the invention with regard to the function of a tuple. In the third aspect, a tuple in the HT-SIG2 field can refer to multiple MPDUs for the same destination device. An additional field 708 is included in a tuple that indicates the number of MPDUs for the respective destination device. The MPDUs and respective fragments of the tuple may or may not be of the same size, as the PDU Length field indicates the total length of all MPDUs for this destination device. With regard to the above-mentioned fields of the second and third aspects of the present invention, these fields are sufficient for an STA to calculate when it should start receiving data and for how long. One advantage of the present invention is that the STA can decide to execute a power-saving scheme when the STA need not receive any data. Fig. 9 shows the sleep-awake periods at the five stations (STA1 to STA6) used as examples in

Figs. 7 and 8 to illustrate the second and third aspects of the invention during the reception of a typical aggregated PSDU with different receivers and the sleep mode of a sixth station STA6, which is not mentioned as receiver in the PSDU. This STA6 can remain in a sleep mode during the whole frame transmission due to HT-SIG2's containing the MAC Addresses of the receiving STAs of this PSDU. It can be seen that STA6 remains at a low level (indicating sleep) throughout the PSDU. In Figure 10 the HT-SIG2 and PSDU-DATA illustrate frame formats of a fourth aspect of the present invention. Similar to previous examples, five stations are illustrated, two of which are transmitting at MCS1, two others at MCS2 and the third one at a different MCS3. One difference that distinguishes this fourth aspect of the invention from, for example, the second aspect of the invention, is that MPDUs using the same MCS are grouped. The following aggregation information is included in the HT-SIG2 field for each group of receiving STAs with the same MCS: • MCS for a group of STAs with the same MCS (MCS Aggregate) • Length 1015 of all aggregates with the same MCS • Nr. Receivers 1016 (to indicate how big the next subfield will be that contains the MAC Addresses of the STAs) • List of Receiver Addresses 1017. Similar to the previously illustrated examples, the PSDU contains all MPDUs (MAC Header + Payload) and attaches to them an MPDU_Delimiter (Length and CRC) 1025 in order to separate MPDUs and to indicate the length of the next MPDU. The MPDU delimiter may, for example, contain the length of the following MPDU, a Cyclic Redundancy Check (CRC) sum as well as a unique pattern. In contrast to the previously illustrated aspects of the invention, in the fourth aspect the PREAMBLE is only used in order to separate aggregates of different MCSs. That is, two MPDUs at the same rate will be separated just with an MPDU_Delimiter, whereas the next MPDU at a different rate will be preceded by a PREAMBLE for synchronization purposes after the sleep-awake phase. The preambles following an aggregate of MPDUs (with the same MCS) may be used by the receiving stations to synchronize and demap the following MPDUs at the desired data rate (indicated in HT-SF2/ MCS Field). Fig. 11 illustrates the HT-SIG2 and PSDU-DATA frame formats of a fifth aspect of the present invention using the previous example of five stations, two of which are transmitting at MCS1, two others at MCS2 and the third one at a different MCS3. In this case, the information contained in HT-SF2 is grouped considering how many MCS groups there are: • MCS for a group of STAs with the same MSC (MCS Aggregate) • Length of all aggregates with the same MCS. Fig. 12 shows the sleep-awake periods at the five stations (STA1-STA5) during the reception of a typical aggregated PSDU according to the fourth and fifth aspects of the invention, and the sleep mode of a STA6, which is not listed as receiver. This STA6 can remain in a sleep mode during the whole frame transmission due to HT-SIG2's containing the MAC Addresses of the receiving STAs of this PSDU. Fig. 13 illustrates, in contrast to the previously discussed aspects of the invention, a sixth aspect of the invention wherein the detailed information about the receivers is not contained in the HT-SIG2 field but inside the PSDU-DATA in an additional MPDU named MRAD (Multiple Receiver Aggregation Descriptor) according to TG Sync specification. This MPDU contains the MAC Addresses of all STAs, whose MPDUs will be included in the following MCS Aggregate. Similar to the fourth aspect of the invention, the PREAMBLE is used to separate aggregates of different MCSs. Optionally, the MRAD also can contain the number of MPDUs for this MAC address and/or the length of all MPDUs intended for the respective address. This latter optional information is useful in case there is just one single MCS in the aggregate, in order to let the intended receivers only wake up when their own MPDUs are transmitted. There are as many MRAD MPDUs as MCS groups. Fig. 14 shows the sleep-awake periods at the five stations (STA1-STA5) during the reception of a typical aggregated PSDU according to the sixth aspect of the invention, and the sleep mode of a STA6, which is not listed as receiver. In contrast to the previously discussed aspects of the invention, STA6 must wake up at the beginning of each MCS aggregate, synchronize with the preamble and decode the MRAD MPDU, in order to check whether its address is mentioned as a receiver. Only if the STA is not listed as receiver can it fall back into the sleep mode. In Fig. 15 the HT-SIG2 and PSDU-DATA frame formats are shown to illustrate a seventh aspect of the present invention using the previously allotted number of five stations, two of which are transmitting at MCS1, two others at MCS2 and the third one at a different MCS3. The detailed information about the receivers is contained in the PSDU-DATA in an additional Super-MRAD MPDU 1525. This Super-MRAD MPDU 1525 contains: • Number of receivers 1527 • MAC addresses 1529 of receivers of this MSC • After each receiver MAC address: length 1531 of the MPDUs for the respective receiver • Optionally: After each receiver MAC address and length: Number of MPDUs for the respective receiver. In contrast to the previously illustrated aspects of the invention, neither MPDUs nor MCS aggregates are separated by preambles. Two different situations can occur depending on the hardware capabilities: Either MPDU delimiters are sufficient to synchronize to an MCS aggregate after waking up or no sleeping during the entire PPDU is possible. In order to provide the necessary length information for those devices that are capable of making use of it, MCS and length information can be included in the HT-SIG2 field: • MCS for a group of STA with the same MCS (MCS Aggregate) • Length of all aggregates with the same MCS. If this information is not included in the HT-SIG2 field the Super-MRAD MPDUs must include an MCS code and as many Super-MRAD MPDUs as different MCSs in the PPDU must be included. However, it is assumed here that the information is included in the HT-SIG2 field. Fig. 16 illustrates the sleep-awake periods at the five stations (STA1-STA5) during the reception of a typical aggregated PSDU according to the sixth aspect of the invention, and the sleep mode of a STA6, which is not listed as receiver. Various modifications can be made to the present invention that do not depart from the spirit of the invention and the scope of the appended claims. For example, the Superframe having a plurality of aggregated packets could have different arrangements of the header than shown, according to need or preference. The systems can use many different types of nodes, and the transmission can be wired or wireless. Protocols other than 802.11 can be used also, so long as they are adapted to accept packet aggregation.

Claims

What is claimed is: 1. A Superframe Protocol Packet Data Unit (PPDU) 215 comprising: a plurality of Medium Access Control (MAC) Protocol Data Units (MPDUs) (205); a PHY layer convergence protocol (210,310) comprising a Super Protocol Data Service Unit (PDSU) adapted for delivery of the MPDUs (205) at different PHY rates; wherein the plurality of MPDUs comprises multi-rate aggregated packets (327).

2. The superframe protocol packet data unit according to claim 1, wherein the PHY layer convergence protocol (210,310) includes in a PDSU header (315) at least one bit identifying the superframe as containing an aggregation of packets.

3. The superframe protocol packet data unit according to claim 2, wherein the PHY layer convergence protocol (310) includes an indication of a length of the super protocol service data unit header (315).

4. The superframe protocol packet data unit according to claim 1, wherein the super protocol service data unit header (315) comprises an aggregation of characteristics for a plurality of MAC management protocol service data units (205).

5. The superframe protocol packet data unit according to claim 4, wherein the characteristics include for each of the plurality of MAC management protocol service data units (205): a receiver MAC address, a preamble type, a data rate, and a length of each respective MAC management protocol service data unit.

6. The superframe protocol packet data unit according to claim 4, including a power -saving feature comprising a virtual carrier sense mechanism.

7. The superframe protocol packet data unit according to claim 6, wherein the virtual carrier sense mechanism of the power -saving feature comprises a super duration identifier.

8. The superframe protocol packet data unit according to claim 1, wherein the PHY layer convergence protocol (310) comprises an IEEE 802.11 layer.

9. The superframe protocol packet data unit according to claim 1, wherein the super protocol service data unit header (315) is arranged to enhance receipt of fragmented MAC service data unit transmissions.

10. The superframe protocol packet data unit according to claim 1, wherein one or more MAC service data units are adapted for delivery to one or more respective stations at different PHY rates.

11. The superframe protocol packet data unit according to claim 1, further comprising a High Throughput Signal Field (HT-SIG2), includes a tuple comprising the following aggregation information for each of a plurality of respective stations, at least some of which transmit at different modulation/coding schemes (MCS), said tuple including : a Receiver (STAs) MAC address; an MCS of a particular MPDU; and a PDU Length.

12. The superframe protocol packet data unit according to claim 11 , wherein said tuple refers to more than one MPDU for the same destination device.

13. The superframe protocol packet data unit according to claim 1, further comprising a High Throughput Signal Field (HT-SIG2), includes a tuple comprising the following aggregation information for each of a plurality of respective stations, at least some of which transmit at different modulation/coding schemes (MCS), said tuple including: a MCS for a group of STAs with the same MCS (MCS Ag gregate); a length (1015) of all aggregates with the same MCS; a receivers number (1016) to indicate how big the next subfield will be that contains the MAC Addresses of the STAs; and, a list of receiver addresses (1017).

14. The superframe protocol packet data unit according to claim 1, further comprising a High Throughput Signal Field (HT-SIG2) includes a tuple comprising the following aggregation information for each of a plurality of respective stations, at least some of which transmit at different modulation/coding schemes (MCS), said tuple including: an MCS for a group of STAs with the same MSC (MCS Aggregate); and a length of all aggregates with the same MCS.

15. The superframe protocol packet data unit according to claim 1, further comprising a Multiple Receiver Aggregation Descriptor (MRAD) (1310) inside a PSDU-DATA field (1305), includes a tuple comprising aggregation information for each of a plurality of r espective stations, at least some of which transmit at different modulation/coding schemes (MCS).

16. The superframe protocol packet data unit according to claim 1, further comprising a Super-Multiple Receiver Aggregation Descriptor (MRAD) (1525) insi de a PSDU-DATA field (1405), includes the following aggregation information for each of a plurality of respective stations, at least some of which transmit at different modulation/coding schemes (MCS), said Super-MRAD (1525) including: a number of receivers (1527); a MAC addresses (1529) of receivers of a respective MSC; and after each receiver MAC address: a length (1531) of the MPDUs for the respective receiver.

17. The superframe protocol packet data unit according to claim 1, wherein after each receiver MAC address (1529) and length field (1531) is arranged in a number of MPDUs for a respective receiver.

18. A system for ulti -rate aggregation of packets, comprising: a plurality of nodes (112, 113, and 114); a station (115); wherein at least one of the plurality of nodes is adapted for receiving a superframe comprising an aggregation of multi -rate packets.

19. The system according to claim 18, wherein one node 114 of the plurality of nodes (112, 113, and 114) has a different PHY rate of transmission.

20. The system according to claim 19, wherein more than one of the plurality of nodes (112, 113, and 114) is adapted for receiving the superframe (125) comprising an aggregation of packets at different transmission rates (127, 128, and 129).

21. The system according to claim 19, wherein at least one of the plurality of nodes (112, 113, and 114), comprises a legacy device (112) that transmits and receives non -aggregated packet frames according to MAC protocols.

22. The system according to claim 19, wherein MAC service data units (205) are deliverable to each of the plurality of nodes at a different transmission rate.

23. The system according to claim 19, wherein an arrangement of aggregated packets is grouped to provide a power savings for the plurality of nodes for transmission and receipt of the superframe.

24. The system according to claim 19, wherein the plurality of nodes comprises stations (112, 113, 114), and an Access Point (115) operating under IEEE 802.11 that are adapted to send/receive a superframe, comprising a plurality of packets.

25. A method for providing a superframe for transmission of data, comprising the following steps: (a) providing a header (300) comprising a preamble (305) and a PHY layer convergence protocol 310; (b) including a super protocol service data unit header (315); (c) providing a plurality of MAC management protocol data units (205) that are grouped together, wherein at least one of the MAC management protocol data units is grouped for delivery to a plurality of respective nodes at different rates.

26. The method according to claim 25, further comprising the following step: (d) including an indication of a length of the super protocol service data unit header (315) in the PHY layer convergence protocol (310).

27. The method according to claim 25, further comprising the following the step: (e) transmitting one or more superframes (125) comprising a plurality of MAC management protocol data units (205) that are grouped together.