Patent ID: 9088393
Filing Date: 2015-07-21
Classification: H04B,H04L,H04W

Abstract:
1. A method for reporting channel state information (CSI) in a wireless local area network system, the method comprising: receiving, by a responding station, a null data packet (NDP) announcement frame to initiate a sounding feedback sequence from a requesting station, the NDP announcement frame including a receiver address field and a station information field, the station information field including an association identifier of the responding station expected to prepare a sounding feedback, wherein the station information field further includes a feedback type indicating whether the sounding feedback from a single station is requested or not, and wherein the receiver address field indicates an address of the responding station identified by the association identifier when the feedback type indicates that the sounding feedback from the single station is requested; receiving, by the responding station, an NDP frame from the requesting station after receiving the NDP announcement frame, the NDP frame having at least one training field but no data field; and transmitting, by the responding station, a CSI report frame to the requesting station, the CSI report frame including CSI report information in a form of angles representing a beamforming feedback matrix that is estimated by the responding station based on the NDP frame, wherein, if the NDP frame is received via a plurality of contiguous channels, the beamforming feedback matrix is estimated based on all of the plurality of contiguous channels, and wherein, if the NDP frame is received via at least one of a plurality of non-contiguous channels, the beamforming feedback matrix is estimated based on only one of the plurality of non-contiguous channels.