Access point, a wireless station and methods therein for multi-user clear to send transmissions

• US 10,075,274 B2
• Filed: 03/03/2016
• Issued: 09/11/2018
• Est. Priority Date: 11/06/2015
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Wilhelmsson, Leif, Kapetanovic, Dzevdan, Nilsson, Thomas
• Primary Examiner(s): TRAN, PHUC H
• Application Number:
  US15/029,386
• Publication Number:
  US 20170264416A1
• Time in Patent Office: 922 Days
• CPC Class Codes: H04L 5/0037 Inter-user or inter-terminal allocation
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 74/006 in the downlink, i.e. towards the terminal
• CPC Class Codes: H04W 74/0816 with collision avoidance
• CPC Class Codes: H04W 8/005 Discovery of network devices, e.g. terminals

Abstract

An Access Point (AP) 402 and a method therein for Multi-User Clear-To-Send (MU CTS) signaling between the AP and at least one wireless station (STA) 404,406. The AP sends a Request To Send (RTS) packet directed to multiple STAs. The RTS packet is indicating at least two STAs, to which the AP would like to transmit, and a configuration of a CTS packet to be used by said at least two STAs when responding to the RTS packet. The configuration enables the AP to identify the at least two STAs when the at least two STAs are transmitting a respective CTS packet. Further the AP receives, from at least one STA, a respective CTS packet transmitted in accordance with the indicated configuration, thereby enabling the AP to identify the at least one STA transmitting the respective CTS packet.

Claims

1. A method, performed by an Access Point (AP), for Multi-User Clear-To-Send (MU CTS) signaling between the AP and at least one wireless station (STA), the method comprising:

sending a Request To Send (RTS) packet directed to multiple STAs, wherein the RTS packet indicates;

at least two STAs to which the AP would like to transmit; and

a configuration of a Clear To Send (CTS) packet to be used by the at least two STAs when responding to the RTS packet, the configuration enabling the AP to identify the at least two STAs when the at least two STAs are transmitting a respective CTS packet; and

receiving, from at least one STA, a respective CTS packet transmitted in accordance with the indicated configuration, thereby enabling the AP to identify the at least one STA transmitting the respective CTS packet.

2. The method of claim 1, wherein the configuration involves assigning a unique signature to be sent in association with the CTS packet, wherein the unique signature comprises a signature sequence uniquely allocated for the respective STAs.

3. The method of claim 2, wherein signature sequences allocated for different STAs are orthogonal to one another.

4. The method of claim 1, wherein different STAs are allocated to different sub-carriers.

5. The method of claim 4, wherein different STAs are allocated to different sub-carriers by adding a single Orthogonal Frequency-Division Multiplexing (OFDM) symbol and using differential encoding based on the phase difference between different sub-carriers.

6. The method of claim 5, wherein different STAs are allocated to different consecutive OFDM symbols.

7. The method of claim 1, wherein different sets of sub-carriers are allocated to different STAs.

8. An Access Point (AP) for Multi-User Clear-To-Send (MU CTS) signaling between the AP and at least one wireless station (STA), the AP comprising:

processing circuitry;

memory containing instructions executable by the processing circuitry whereby the AP is configured to;

send a Request To Send (RTS) packet directed to multiple STAs, wherein the RTS packet indicates;

at least two STAs to which the AP would like to transmit; and

a configuration of a Clear To Send (CTS) packet to be used by the at least two STAs when responding to the RTS packet, the configuration enabling the AP to identify the at least two STAs when the at least two STAs are transmitting a respective CTS packet; and

receive, from at least one STA, a respective CTS packet transmitted in accordance with the indicated configuration, thereby enabling the AP to identify the at least one STA transmitting the respective CTS packet.

9. The AP of claim 8, wherein the configuration involves assigning a unique signature to be sent in association with the CTS packet, wherein the unique signature comprises a signature sequence uniquely allocated for the respective STAs.

10. The AP of claim 9, wherein signature sequences allocated for different STAs are orthogonal to one another.

11. The AP of claim 8, wherein different STAs are allocated to different sub-carriers.

12. The AP of claim 11, wherein different STAs are allocated to different sub-carriers by adding a single Orthogonal Frequency-Division Multiplexing (OFDM) symbol and using differential encoding based on the phase difference between different sub-carriers.

13. The AP of claim 10, wherein different STAs are allocated to different consecutive Orthogonal Frequency-Division Multiplexing (OFDM) symbols.

14. The AP of claim 8, wherein different sets of sub-carriers are allocated to different STAs.

15. A method, performed by a wireless station (STA), for Multi-User Clear-To-Send (MU CTS) signaling between an Access Point (AP) and at least one wireless station (STA), the method comprising:

receiving a Request To Send (RTS) packet from the AP, wherein the RTS packet indicates to the STA;

at least two STAs to which the AP would like to transmit; and

a configuration of a Clear To Send (CTS) packet to be used by the at least two STAs when responding to the RTS packet, the configuration enabling the AP to identify the respective one of the at least two STAs when the at least two STAs are transmitting the CTS packets; and

sending, to the AP, a CTS packet in accordance with the indicated configuration, thereby enabling the AP to identify the STA.

16. The method of claim 15, further comprising associating a unique signature with the CTS packet, wherein the unique signature comprises a signature sequence uniquely allocated for the STA.

17. The method of claim 16, further comprising adding additional information in the signature, the additional information comprising at least one of interference strength and Modulation Coding Scheme (MCS) information.

18. The method of claim 16, wherein the associating comprises associating the unique signature with the CTS packet by augmenting the CTS packet in time by adding the signature to a common part of the CTS packet.

19. The method of claim 16, wherein the signature is added after a common part of the CTS packet.

20. The method of claim 19, wherein a gap is introduced between the common part of the CTS packet and a signature part comprising the unique signature.

21. The method of claim 20, wherein the gap has a gap length corresponding to a Short InterFrame Space (SIFS) or a Reduced InterFrame Space (RIFS).

22. The method of claim 16, wherein the associating comprises associating the signature with the CTS packet by augmenting the CTS packet in frequency by adding subcarriers to a common part of the CTS packet.

23. A wireless station (STA) for Multi-User Clear-To-Send (MU CTS) signaling between an Access Point (AP) and at least one wireless station (STA), the STA comprising:

processing circuitry;

memory containing instructions executable by the processing circuitry whereby the STA is configured to;

receive a Request To Send (RTS) packet from the AP, wherein the RTS packet indicates, to the STA;

at least two STAs to which the AP would like to transmit;

a configuration of a Clear To Send (CTS) packet to be used by the at least two STAs when responding to the RTS packet, the configuration enabling the AP to identify the at least two STAs when the at least two STAs are transmitting the CTS packets; and

send, to the AP, a CTS packet in accordance with the indicated configuration, thereby enabling the AP to identify the STA.

24. The STA of claim 23, wherein the instructions, when executed by the processing circuitry, configure the STA to associate a unique signature with the CTS packet, wherein the unique signature comprises a signature sequence uniquely allocated for the STA.

25. The STA of claim 24, wherein the instructions, when executed by the processing circuitry, configure the STA to add additional information in the signature, the additional information comprising at least one of interference strength and Modulation Coding Scheme (MCS) information.

26. The STA of claim 24, wherein the instructions, when executed by the processing circuitry, configure the STA to associate the unique signature with the CTS packet by augmenting the CTS packet in time by adding the signature to a common part of the CTS packet.

27. The STA of claim 26, wherein the instructions, when executed by the processing circuitry, configure the STA to add the signature after a common part of the CTS packet.

28. The STA of claim 27, wherein the instructions, when executed by the processing circuitry, configure the STA to introduce a gap between the common part of the CTS packet and a signature part comprising the unique signature.

29. The STA of claim 28, wherein the gap has a gap length corresponding to a Short InterFrame Space (SIFS) or a Reduced InterFrame Space (RIFS).

30. The STA of claim 24, wherein the instructions, when executed by the processing circuitry, configure the STA to associate the unique signature with the CTS packet by augmenting the CTS packet in frequency by adding subcarriers to a common part of the CTS packet.

31. A computer program product stored in a non-transitory computer readable medium for Multi-User Clear-To-Send (MU CTS) signaling between an Access Point (AP) and at least one wireless station (STA), the computer program product comprising software instructions which, when run on the processing circuitry of the AP, causes the AP to:

send a Request To Send (RTS) packet directed to multiple STAs, wherein the RTS packet indicates;

at least two STAs to which the AP would like to transmit; and

a configuration of a Clear To Send (CTS) packet to be used by the at least two STAs when responding to the RTS packet, the configuration enabling the AP to identify the at least two STAs when the at least two STAs are transmitting a respective CTS packet; and

receive, from at least one STA, a respective CTS packet transmitted in accordance with the indicated configuration, thereby enabling the AP to identify at least one STA transmitting the respective CTS packet.

32. A computer program product stored in a non-transitory computer readable medium for Multi-User Clear-To-Send (MU CTS) signaling between an Access Point (AP) and at least one wireless station (STA), the computer program product comprising software instructions which, when run on the processing circuitry of a first STA, causes the first STA to:

receive a Request To Send (RTS) packet from the AP, wherein the RTS packet indicates to the first STA;

at least two STAs to which the AP would like to transmit; and

a configuration of a Clear To Send (CTS) packet to be used by the at least two STAs when responding to the RTS packet, the configuration enabling the AP to identify the respective one of the at least two STAs when the at least two STAs are transmitting the CTS packets; and

send, to the AP, a CTS packet in accordance with the indicated configuration, thereby enabling the AP to identify the first STA.