Patent ID: 8761098

Claim:
A method for transmitting, by a base station (BS), pilot signals in a downlink multiple input multiple output (MIMO) system the method comprising: mapping, by the BS which includes ‘N’ transmit antennas 0 to N−1 for transmission of cell-specific pilot symbols R 0 to R N-1 and ‘M-N’ transmit antennas N to M−1 for transmission of user-specific pilot symbols R N to R M-1 , where M>N, the user-specific pilot symbols R N to R M-1 for channel measurement to a resource block (RB) in a downlink subframe; broadcasting, by the BS, RB information indicating a position of the RB to which the user-specific pilot symbols R N to R M-1 are mapped; and transmitting the cell-specific pilot symbols R 0 to R N-1 and the user-specific pilot symbols R N to R M-1 in the downlink subframe, wherein the downlink subframe includes a plurality of orthogonal frequency division multiplexing (OFDM) symbols in a time axis and a plurality of RBs in a frequency axis, wherein the user-specific pilot symbols R N to R M-1 are dedicated to a second UE supporting up to the ‘M’ transmit antennas of the BS and transmitted only on the RB through the transmit antennas N to M−1 when the RB is assigned to the second UE, where R i is a user-specific pilot symbol transmitted through a transmit antenna i, wherein i is an integer that is one of N to M−1, wherein the cell-specific pilot symbols R 0 to R N-1 are transmitted via the transmit antenna 0 to N−1 to a first user equipment (UE) supporting up to the ‘N’ transmit antennas of the BS and the second UE, where R j is a cell-specific pilot symbol transmitted via a transmit antenna j, wherein j is an integer that is one of 0 to N−1, wherein the user-specific pilot symbols R N to R M-1 are dedicated to the second UE and transmitted only on the RB via the transmit antennas N to M−1 when the RB is assigned to the second UE, and wherein the RB information is broadcast to allow the first UE, as well as the second UE, to use the user-specific pilot symbols R N to R M-1 for channel measurement.