Patent ID: 7643793

Claim:
A method for relaying a data packet in a downlink of a wireless communication system, in which a base station (BS) transmits the data packet to subscriber stations (SSs) by using relay stations (RSs), the method comprising the steps of: broadcasting, by the BS, a BS pilot symbol, which includes information about an RS to be used for relay transmission in a next frame; receiving, by each RS appointed to be used for relay transmission in the next frame, the BS pilot symbol, measuring a first signal-to-noise ratio (SNR) information which is SNR information between the RS and the BS, transmitting a relay pilot symbol to the SSs when the first SNR information is equal to or greater than a threshold value, and notifying the BS that the RS has transmitted the relay pilot symbol to the SSs; receiving, by each SS, the BS pilot symbol, measuring a second SNR information which is SNR information between the SS and the BS, receiving the relay pilot symbol, measuring a third SNR information which is an SNR information between the SS and each RS having transmitted the relay pilot symbol, and determining whether the data packet is received via the RS, based on the second and third SNR information; feeding the third SNR information from each SS back to the BS, when the SS determines that the data packet is received via the RS; performing, by the BS, a data packet scheduling based on the third SNR information fed back from the SSs, and transmitting the data packet to RSs which have transmitted the relay pilot symbol; and relaying, by the RSs having transmitted the relay pilot symbol, the data packet transmitted from the BS to the SSs.