TECHNIQUES FOR MU-MIMO SOUNDING SEQUENCE PROTECTION

• US 20180109298A1
• Filed: 10/14/2016
• Published: 04/19/2018
• Est. Priority Date: 10/14/2016
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: ELSHERIF, AHMED RAGAB, HOUGHTON, NATHANIEL DAVID
• Granted Patent: US 10,135,504 B2
• Time in Patent Office: Days
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04W 74/0816 with collision avoidance
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

The disclosure provides techniques for sounding sequence protection in multi-user multiple-input-multiple-output (MU-MIMO) communications for wireless local area networks (WLANs). An access point (AP) may select a station (STA) from multiple STAs in a MU-MIMO group. The AP may then transmit a request-to-send (RTS) frame, where the RTS is addressed to the selected STA. The AP may receive a clear-to-send (CTS) frame from the selected station and may perform, in response to receiving the CTS frame, a sounding sequence with the MU-MIMO group. After completion of the sounding sequence, the AP may transmit MU-MIMO data communications to at least one of the STAs in the MU-MIMO group.

Claims

1. An access point for wireless communications, comprising:

a transceiver;

a memory; and

a processor communicatively coupled to the transceiver and the memory, the processor being configured to;

select a single wireless station (STA) from a plurality of STAs in a multi-user multiple-input-multiple-output (MU-MIMO) group;

transmit, via the transceiver, a single request-to-send (RTS) frame for the MU-MIMO group, the single RTS frame being addressed only to the selected STA;

receive, via the transceiver, a single clear-to-send (CTS) frame for the MU-MIMO group from the selected STA;

perform, in response to receiving the single CTS frame from the selected STA, a sounding sequence with the MU-MIMO group having the plurality of STAs; and

transmit, via the transceiver and after completion of the sounding sequence, MU-MIMO data communications to at least one of the plurality of STAs in the MU-MIMO group.

2. The access point of claim 1, wherein the processor is configured to randomly select the selected STA from the plurality of STAs in the MU-MIMO group.

3. The access point of claim 1, wherein the processor is configured to select the selected STA from the plurality of STAs in the MU-MIMO group based on a round robin scheme.

4. The access point of claim 1, wherein the processor is configured to select as the selected STA a first STA in the sounding sequence configured to send back a compressed beam-forming feedback (CBF) in response to a null data packet (NDP) of the sounding sequence.

5. The access point of claim 1, wherein the processor is configured to select the selected STA from the plurality of STAs in the MU-MIMO group based on a token assignment and decrement scheme.

6. The access point of claim 5, wherein the processor is configured to perform the token assignment and decrement scheme by being configured to:

assign a token to each STA in the plurality of STAs in the MU-MIMO group; and

decrement the token for the STA to which the RTS frame is transmitted.

7. The access point of claim 5, wherein processor is configured to perform the token assignment and decrement scheme by being configured to:

assign a fist number of tokens to a first STA from the plurality of STAs in the MU-MIMO group; and

assign a second number of tokens to a second STA from the plurality of STAs in the MU-MIMO group,

wherein the first number of tokens is greater than the second number of tokens, and

wherein a number of sounding sequence failures associated with the first STA is greater than a number of sounding sequence failures associated with the second STA.

8. The access point of claim 1, wherein a duration of the single RTS frame is configured to cover a duration of the single CTS frame, a null data packet announcement (NDPA), and an NDP.

9. The access point of claim 1, wherein a duration of the single RTS frame is configured to cover a duration of the single CTS frame and a duration of the sounding sequence.

10. The access point of claim 1, wherein a duration of the single RTS frame is configured to cover a duration of the single CTS frame, a duration of the sounding sequence, and a duration of an MU PLCP protocol data unit (PPDU) transmission.

11. The access point of claim 1, wherein a duration of the single CTS frame is configured to cover a duration of an NDPA and an NDP.

12. The access point of claim 1, wherein a duration of the single CTS frame is configured to cover a duration of the sounding sequence.

13. The access point of claim 1, wherein a duration of the single CTS frame is configured to cover a duration of the sounding sequence and a duration of an MU PPDU transmission.

14. The access point of claim 1, wherein the processor is further configured to:

identify a condition indicating a need for RTS-CTS sequence protection of the sounding sequence; and

trigger the transmission of the single RTS frame in response to identifying the condition.

15. The access point of claim 14, wherein the condition is one or more of:

a register setting;

a detection of an overlapping basic service set (OBSS);

a periodic measurement to determine whether RTS-CTS sequence protection enhances throughout;

or

a number of sounding sequence failures satisfies a threshold over a specified period of time.

16. The access point of claim 1, wherein the processor is further configured to:

select, in addition to the selected STA, one or more STAs from the plurality of STAs based on one or both of packet error rate (PER) or collision statistics, the selected one or more STAs and the selected STA being less than the plurality of STAs in the MU-MIMO group,

transmit, via the transceiver and in addition to the single RTS frame, a single RTS frame to each of the selected one or more STAs, each additional single RTS frame being addressed only to a respective one of the selected one or more STAs,

receive, via the transceiver and in addition to the single CTS frame, a single CTS frame from each of the selected one or more STAs, and

perform, in response to receiving the single CTS frame from the selected STA and the additional single CTS frame from each of the selected one or more STAs, the sounding sequence with the MU-MIMO group having the plurality of STAs.

17. A method for wireless communications, comprising:

selecting a single wireless station (STA) from a plurality of STAs in a multi-user multiple-input-multiple-output (MU-MIMO) group;

transmitting, from an access point, a single request-to-send (RTS) frame for the MU-MIMO group, the single RTS frame being addressed only to the selected STA;

receiving, at the access point, a single clear-to-send (CTS) frame for the MU-MIMO group from the selected STA;

performing, in response to receiving the single CTS frame from the selected STA, a sounding sequence with the MU-MIMO group having the plurality of STAs; and

transmitting, after completion of the sounding sequence, MU-MIMO data communications to at least one of the plurality of STAs in the MU-MIMO group.

18. The method of claim 17, wherein selecting the single STA from the plurality of STAs in the MU-MIMO group comprises selecting a first STA in the sounding sequence configured to send back a compressed beam-forming feedback (CBF) in response to a null data packet (NDP) of the sounding sequence.

19. The method of claim 17, wherein selecting the single STA from the plurality of STAs in the MU-MIMO group comprises selecting the single STA based on a token assignment and decrement scheme.

20. The method of claim 19, wherein the token assignment and decrement scheme comprises:

assigning a token to each STA in the plurality of STAs in the MU-MIMO group; and

decrementing the token for the STA to which the single RTS frame is transmitted.

21. The method of claim 19, wherein the token assignment and decrement scheme comprises:

assigning a fist number of tokens to a first STA from the plurality of STAs in the MU-MIMO group; and

assigning a second number of tokens to a second STA from the plurality of STAs in the MU-MIMO group,

wherein the first number of tokens is greater than the second number of tokens, and

wherein a number of sounding sequence failures associated with the first STA is greater than a number of sounding sequence failures associated with the second STA.

22. The method of claim 17, wherein a duration of the single RTS frame is configured to cover a duration of the single CTS frame, a null data packet announcement (NDPA), and an NDP.

23. The method of claim 17, wherein a duration of the single RTS frame is configured to cover a duration of the single CTS frame and a duration of the sounding sequence.

24. The method of claim 17, wherein a duration of the single RTS frame is configured to cover a duration of the single CTS frame, a duration of the sounding sequence, and a duration of an MU PLCP protocol data unit (PPDU) transmission.

25. The method of claim 17, wherein a duration of the single CTS frame is configured to cover a duration of an NDPA and an NDP.

26. The method of claim 17, wherein a duration of the single CTS frame is configured to cover a duration of the sounding sequence, or the duration of the sounding sequence and a duration of an MU PPDU transmission.

27. The method of claim 17, further comprising:

identifying a condition indicating a need for RTS-CTS sequence protection of the sounding sequence; and

triggering the transmission of the single RTS frame in response to identifying the condition,

wherein the condition is one or more of;

a register setting;

a detection of an overlapping basic service set (OBSS);

a periodic measurement to determine whether RTS-CTS sequence protection enhances throughout;

or

a number of sounding sequence failures satisfies a threshold over a specified period of time.

28. The method of claim 17, further comprising:

selecting, in addition to the selected STA, one or more STAs from the plurality of STAs based on one or both of packet error rate (PER) or collision statistics, the selected one or more STAs and the selected STA being less than the plurality of STAs in the MU-MIMO group, wherein;

transmitting the single RTS frame further comprises transmitting a single RTS frame to each of the selected one or more STAs, each additional single RTS frame being addressed only to a respective one of the selected one or more STAs,

receiving the single CTS frame further comprises receiving a single CTS frame from each of the selected one or more STAs, and

performing the sounding sequence is in response to receiving the single CTS frame from the selected STA and the additional single CTS frame from each of the one or more STAs.

29. An access point for wireless communications, comprising:

means for selecting a single wireless station (STA) from a plurality of STAs in a multi-user multiple-input-multiple-output (MU-MIMO) group;

means for transmitting a single request-to-send (RTS) frame for the MU-MIMO group, the single RTS frame being addressed only to the selected STA;

means for receiving a single clear-to-send (CTS) frame for the MU-MIMO group from the selected STA;

means for performing, in response to receiving the single CTS frame from the selected STA, a sounding sequence with the MU-MIMO group having the plurality of STAs; and

means for transmitting, after completion of the sounding sequence, MU-MIMO data communications to at least one of the plurality of STAs in the MU-MIMO group.

30. A non-transitory computer-readable medium storing computer executable code for wireless communications, the code comprising:

code for selecting a single wireless station (STA) from a plurality of STAs in a multi-user multiple-input-multiple-output (MU-MIMO) group;

code for transmitting a single request-to-send (RTS) frame for the MU-MIMO group, the RTS frame being addressed only to selected STA;

code for receiving a single clear-to-send (CTS) frame for the MU-MIMO group from the selected STA;

code for performing, in response to receiving the single CTS frame from the selected STA, a sounding sequence with the MU-MIMO group having the plurality of STAs; and

code for transmitting, after completion of the sounding sequence, MU-MIMO data communications to at least one of the plurality of STAs in the MU-MIMO group.