Apparatus and method for obtain channel state information in wireless relay networks

An apparatus and a method for obtaining channel state information in wireless relay networks are provided to reduce feedback signals and minimize a waste of resources, in the case of using a fixed RS(Relay Station), and to transmit signals adaptively according to channel conditions by using the channel information between a source, an RS, and a BS(Base Station). A BS, if uplink signals are received from an RS and an MS(Mobile Station), estimates the channels of SD(Source-to-Destination) and SR(Source-to-Relay station) links using the pilot signals contained in the received uplink signals(311,313). Also the RS receives an uplink signal from the MS and estimates the channel of an RD(Relay station-to-Destination) link using the pilot signal contained in the received uplink signal(312,315). Then the RS creates a pilot signal to be transmitted to the BS and adjusts the power of the created pilot signal using the power of the pilot signal contained in the received uplink signal(317). The RS transmits the created pilot signal to the BS(319). The BS measures the power of the pilot signal transmitted from the RS and estimates the channel of the RD link using the measured pilot signal power and the estimated SR link channel value(321).