Patent ID: 8428172

Claim:
A method of transmitting a midamble, performed by a base station, for channel estimation of multiple antennas in a system having segregated uplink and downlink frequency bands, the method comprising: transmitting midamble information comprising a duration and a midamble period to a user equipment (UE), wherein the duration indicates a valid time of the midamble information and the midamble period indicates a downlink frame at which a midamble is transmitted among a plurality of downlink frames; and transmitting the midamble on a predetermined downlink subframe among a plurality of downlink subframes included in the downlink frame to the UE by using the multiple antennas, wherein the midamble is mapped to a last orthogonal frequency division multiplexing (OFDM) symbol of the predetermined downlink subframe in a time domain, and to subcarriers determined by a total number of the multiple antennas and an index of an antenna to be mapped in a frequency domain, and wherein the subcarriers corresponding to an OFDM symbol used to transmit the midamble are allocated according to the following equation: - ( N used / 2 ) + n + 2 ⁢ k × ⌈ N t 2 ⌉ where n denotes an index of an antenna to be mapped, Nt denotes a total number of the multiple antennas, k denotes a subcarrier index, and N used denotes a total number of subcarriers in use.