SCHEDULING FOR ORTHOGONAL FREQUENCY DIVISION MULTIPLE ACCESS (OFDMA) TRANSMISSIONS IN A WIRELESS LOCAL AREA NETWORK (WLAN)

• US 20160226635A1
• Filed: 01/26/2016
• Published: 08/04/2016
• Est. Priority Date: 02/03/2015
• Status: Active Grant

• Current Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Incorporated (STMicroelectronics NV)
• Inventors: Chu, Liwen, Vlantis, George A.
• Granted Patent: US 9,991,996 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04L 1/16 in which the return channel carries supervisory signals, e.g. repetition request signals
• CPC Class Codes: H04L 1/1607 Details of the supervisory signal
• CPC Class Codes: H04L 1/1854 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/003 Arrangements for allocating sub-channels of the transmission path
• CPC Class Codes: H04L 5/0037 Inter-user or inter-terminal allocation
• CPC Class Codes: H04W 72/04 Wireless resource allocation
• CPC Class Codes: H04W 72/121 for groups of terminals or users
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 74/0816 with collision avoidance
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

An access point (AP) contends for a medium during a contention period in order to obtain exclusive control of the medium for a certain time period that may include one or more transmission opportunities. The AP and client stations (STAs) communicate during the time period using orthogonal frequency division multiple access (OFDMA) techniques with scheduled use (i.e., allocation) of sub-channels of the medium. The AP controls this scheduling for down-link and up-link communications by sending control signaling to inform the STAs of the resource allocation schedule which specifies STAs involved in the OFDMA communications along with the sub-channel identification bandwidth allocated to each STA. The control signaling may be a combination of physical layer (PHY) and medium access control layer (MAC) communicated information.

Claims

1. A method for orthogonal frequency division multiple access (OFDMA) communication in a wireless local area network (WLAN) including an access point (AP) and a plurality of client stations (STAs), comprising:

obtaining by the AP of exclusive control of a wireless communications medium including a plurality of sub-channels for a time period;

determining by the AP of an allocation of one or more sub-channels to certain ones of the STAs for use in said time period for OFDMA communications; and

sending by the AP at a beginning of the time period on each of the plurality of sub-channels of a control frame including for each of said certain ones of the STAs;

a) an identification of the STA;

b) an identification of one or more sub-channels allocated to that STA; and

c) an identification of a bandwidth to use for communications with that STA.

2. The method of claim 1, wherein said control frame specifies whether the OFDMA communications with the certain ones of the STAs during said time period after the sending of the control frame are to be down-link communications from the AP to the certain ones of the STAs.

3. The method of claim 2, further comprising sending by the AP of simultaneous Aggregated MAC Protocol Data Unit (A-MPDU) communications using OFDMA to the certain ones of the STAs, said simultaneous A-MPDU communications having a same start time and same finish time within said time period.

4. The method of claim 3, further comprising issuing, after said finish time, by the STAs of block acknowledgement of received A-MPDU communications from the AP.

5. The method of claim 4, wherein STA issuance of the block acknowledgement is made in response to receipt of a block acknowledgement request transmitted by the AP.

6. The method of claim 5, further comprising transmitting the block acknowledgement request by the AP on all sub-channels used for the simultaneous A-MPDU communications.

7. The method of claim 6, wherein block acknowledgement issued by the STA is transmitted by the STA on all sub-channels used for the simultaneous A-MPDU communications.

8. The method of claim 3, wherein each A-MPDU communication includes a physical layer protocol data unit (PPDU), said PPDU including a physical layer convergence procedure (PLCP) header including signaling information, and further comprising sending by the AP in the PLCP header a first signaling information field including a flag specifying whether the PPDU of the A-MPDU communication is an OFDMA communication.

9. The method of claim 8, further comprising sending by the AP in the PLCP header a second signaling information field specifying for the STA the one or more sub-channels allocated to that STA.

10. The method of claim 9, further comprising sending by the AP in the PLCP header a third signaling information field specifying for the STA the bandwidth allocated to that STA on the one or more sub-channels.

11. The method of claim 10, further comprising sending by the AP in the PLCP header a fourth signaling information field specifying other STAs assigned to belong in a group with said STA for OFDMA communications.

12. The method of claim 11, further comprising sending by the AP in the PLCP header a fifth signaling information field specifying one or more sub-channels allocated to said other STAs in said group.

13. The method of claim 1, wherein the control frame is a medium access layer (MAC) control frame.

14. The method of claim 1, wherein said control frame specifies whether the OFDMA communications with the certain ones of the STAs during said time period after the sending of the control frame are to be up-link communications from the AP to the certain ones of the STAs.

15. The method of claim 14, further comprising sending by the certain ones of the STAs of simultaneous Aggregated MAC Protocol Data Unit (A-MPDU) communications using OFDMA to the AP, said simultaneous A-MPDU communications having a same start time and same finish time within said time period.

16. The method of claim 15, further comprising issuing, after said finish time, by the AP of a block acknowledgement of received A-MPDU communications from the STAs.

17. The method of claim 16, wherein the block acknowledgement is transmitted by the AP on all sub-channels used for the simultaneous A-MPDU communications.

18. A method for orthogonal frequency division multiple access (OFDMA) communication in a wireless local area network (WLAN) including an access point (AP) and a plurality of client stations (STAs), comprising:

obtaining by the AP of exclusive control of a wireless communications medium including a plurality of sub-channels for a time period;

determining by the AP of an allocation of one or more sub-channels to certain ones of the STAs for use in said time period for OFDMA communications; and

sending by the AP of simultaneous Aggregated MAC Protocol Data Unit (A-MPDU) communications using OFDMA to the certain ones of the STAs, said simultaneous A-MPDU communications having a same start time and same finish time within said time period.

19. The method of claim 18, further comprising issuing, after said finish time, by the STAs of block acknowledgement of received A-MPDU communications from the AP.

20. The method of claim 19, wherein STA issuance of the block acknowledgement is made in response to receipt of a block acknowledgement request transmitted by the AP.

21. The method of claim 20, further comprising transmitting the block acknowledgement request by the AP on all sub-channels used for the simultaneous A-MPDU communications.

22. The method of claim 21, wherein block acknowledgement issued by the STA is transmitted by the STA on all sub-channels used for the simultaneous A-MPDU communications.

23. The method of claim 18, wherein each A-MPDU communication includes a physical layer protocol data unit (PPDU), said PPDU including a physical layer convergence procedure (PLCP) header including signaling information, and further comprising sending by the AP in the PLCP header a first signaling information field including a flag specifying whether the PPDU of the A-MPDU communication is an OFDMA communication.

24. The method of claim 23, further comprising sending by the AP in the PLCP header a second signaling information field specifying for the STA the one or more sub-channels allocated to that STA.

25. The method of claim 24, further comprising sending by the AP in the PLCP header a third signaling information field specifying for the STA the bandwidth allocated to that STA on the one or more sub-channels.

26. The method of claim 25, further comprising sending by the AP in the PLCP header a fourth signaling information field specifying other STAs assigned to belong in a group with said STA for OFDMA communications.

27. The method of claim 26, further comprising sending by the AP in the PLCP header a fifth signaling information field specifying one or more sub-channels allocated to said other STAs in said group.