A method and apparatus for channel estimation for radio link between a base station and a relay station in a radio communication system are disclosed. A method for receiving a downlink signal at a relay node in a wireless communication system, the method comprising receiving downlink control information by demodulating a R-PDCCH of a first RB pair based on a downlink channel estimated by a DMRS in the first resource block (RB) pair; and receiving downlink data by demodulating a PDSCH of the one or more RB pairs contiguous to the first RB pair based on a downlink channel estimated by a DMRS in the one or more RB pairs, wherein, if the PDSCH is assigned to the first RB pair, the downlink channel is estimated on the assumption that the same precoder is applied to one RB bundle including the first RB pair and the one or more RB pairs.