Patent ID: 9363774
Filing Date: 2016-06-07
CPC Classification: H04L,H04W

Claim Text:
1. A method for allowing a station to transmit a sounding signal in a multiple-antenna wireless communication system, the method comprising receiving, by the station, a first frame including a group defining field from an access point (AP), the group defining field including information on a group identifier of a plurality of stations being receivers of a multi user (MU)-multiple input multiple output (MIMO) transmission of the AP, the plurality of the stations including the station; receiving, by the station, a second frame including a training request (TRQ) field and an antenna field, the TRQ field including information on triggering each transmission of sounding physical layer protocol data units (PPDUs) of each of the plurality of the stations for a channel estimation between the AP and the each of the plurality of the stations and the antenna field including information on a number of antennas of the each of the plurality of the stations used to transmit each of the sounding PPDUs; determining, by the station, a transmission time of a sounding PPDU based on the antenna field; and transmitting, by the station, the sounding PPDU to the AP based on the transmission time, wherein the group defining field further includes information on a transmission order of the sounding PPDU and each of at least one sounding PPDU transmitted by each of at least one remaining station without the station included in the plurality of the stations, wherein the transmission time increases proportional to a sum of a number of antennas of at least one station among the at least one remaining station transmitting another sounding PPDU before the station transmits the sounding PPDU when the station is configured to wait a minimum time to transmit the sounding PPDU, wherein the number of antennas of the at least one station is determined based on the information on the transmission order and the antenna field, wherein the transmission time increases proportional to a maximum number of layers supported by the AP when the station is configured to wait a maximum time to transmit the sounding PPDU, and wherein a number of long training fields (LTFs) in the sounding PPDU is determined based on information on the number of antennas of the station included in the antenna field.