Method and apparatus of link adaptation in wireless local area network

• US 9,350,428 B2
• Filed: 12/01/2011
• Issued: 05/24/2016
• Est. Priority Date: 12/01/2010
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Kang, Byeong Woo, Sohn, Ill Soo, Lee, Dae Won, Seok, Yong Ho
• Primary Examiner(s): Ng, Fang
• Application Number:
  US13/991,158
• Publication Number:
  US 20130250904A1
• Time in Patent Office: 1,636 Days
• Field of Search: 370/329, 370/334, 370/338, 455/13.3
• US Class Current: 1/1
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0031 Multiple signaling transmission H04L1/1664, F15 take precedence
• CPC Class Codes: H04L 1/1685 the supervisory signal being transmitted in response to a specific request, e.g. to a polling signal
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

A method of link adaptation performed by an access point supporting multi user(MU) multiple input multiple output(MIMO) in wireless local area network system is provided. The method includes transmitting, to a first station, a physical layer convergence procedure (PLCP) protocol data unit (PPDU) containing a modulation and coding scheme(MCS) request(MRQ) and receiving, from the first station, a MCS feedback(MFB) in response to the MRQ, wherein the first station is one of destination stations of MU-MIMO transmission performed by the access point, and the MFB includes a recommended MCS value computed, by the first station, on the assumption that the first station, as a member of the destination stations, receives data transmitted over at least one spatial stream allocated to the first station in MU-MIMO transmission.

Claims

1. A method for a wireless local area network, the method comprising:

transmitting, by a requesting station, a Multi User-Physical layer Protocol Data Unit (MU-PPDU) to a plurality of responding stations, the MU PPDU including a plurality of data frames for the plurality of responding stations,

wherein at least one of the plurality of data frames is a Quality of Service (QoS) Null frame that includes an ACK policy field that identifies an ACK policy for a respective responding station,

wherein only a QoS Null frame for a first station of the plurality of responding stations includes an ACK policy field value that identifies the corresponding ACK policy to be a normal ACK corresponding to an immediate ACK response, and

wherein the QoS Null frame for the first station also includes a Modulation and Coding Scheme Feedback Request (MRQ) field that indicates whether the first station is requested to send a Modulation and Coding Scheme Feedback (MFB); and

receiving, by the requesting station only from the first station based on the ACK policy, an acknowledgment (ACK) frame for the QoS Null frame after a short interframe space (SIFS) period,

wherein only when the MRQ field indicates that the first station is requested to send the MFB does the ACK frame from the first station include a MCS estimate generated by the first station based on the MU-PPDU, and

wherein remaining data frames of the plurality of data frames do not contain ACK policies for the immediate ACK response.

2. The method of claim 1, wherein the MU-PPDU includes a group identifier indicating the plurality of responding stations.

3. The method of claim 1, further comprising:

transmitting, by the requesting station, a block ACK request frame to a second station of the plurality of responding stations.

4. The method of claim 3, wherein a data frame for the second station includes an ACK policy field that is set to a value indicating a block ACK.

5. The method of claim 1, wherein the ACK policy field in the QoS Null frame has two bits.

6. The method of claim 1, wherein the QoS Null frame has no data for the first station of the plurality of responding stations.

7. The method of claim 1, wherein the MRQ field is included in a Medium Access Control (MAC) header of the QoS Null frame.

8. The method of claim 1, wherein the MRQ field has a single bit.

9. A device for a wireless local area network, the device comprising:

a transceiver configured to receive and transmit radio signals; and

a processor operatively coupled with the transceiver and configured to;

instruct the transceiver to transmit a Multi User-Physical layer Protocol Data Unit (MU-PPDU) to a plurality of responding stations, the MU PPDU including a plurality of data frames for the plurality of responding stations,

wherein at least one of the plurality of data frames is a Quality of Service (QoS) Null frame that includes an ACK policy field that identifies an ACK policy for a respective responding station,

wherein only a QoS Null frame for a first station of the plurality of responding stations includes an ACK policy field value that identifies the corresponding ACK policy to be a normal ACK corresponding to an immediate ACK response, and

wherein the QoS Null frame for the first station also includes a Modulation and Coding Scheme Feedback Request (MRQ) field that indicates whether the first station is requested to send a Modulation and Coding Scheme Feedback (MFB); and

instruct the transceiver to receive, only from the first station based on the ACK policy, an acknowledgment (ACK) frame for the QoS Null frame after a short interframe space (SIFS) period,

wherein only when the MRQ field indicates that the first station is requested to send the MFB does the ACK frame from the first station include a MCS estimate generated by the first station based on the MU-PPDU, and

wherein remaining data frames of the plurality of data frames do not contain ACK policies for the immediate ACK response.

10. The device of claim 9, wherein the MU-PPDU includes a group identifier indicating the plurality of responding stations.

11. The device of claim 9, wherein the processor is configured to instruct the transceiver to transmit a block ACK request frame to a second station of the plurality of responding stations.

12. The device of claim 11, wherein a data frame for the second station includes an ACK policy field that is set to a value indicating a block ACK.

13. The device of claim 9, wherein the ACK policy field in the QoS Null frame has two bits.

14. The device of claim 9, wherein the QoS Null frame has no data for the first station of the plurality of responding stations.