Patent ID: 8422356

Claim:
A base station used in a mobile communications system which uses orthogonal frequency division multiplexing (OFDM) for downlink, comprising: a unit which provides a control signal; a unit which provides a reference signal; a unit which multiplexes the control signal and the reference signal, and generates a transmit symbol; and a unit which inverse Fourier transforms the transmit symbol and wirelessly transmits the transformed transmit symbol, wherein a first sequence including a random code sequence and a second sequence belonging to an orthogonal-code sequence group are multiplied with the reference signal, mutually different one of the orthogonal code sequences are used in respective multiple sectors belonging to a same cell, and different ones of the random code sequences are used in respective two or more of the cells, wherein a reference signal transmitted in one sector among the multiple sectors and a reference signal transmitted in another sector among the multiple sectors are time and frequency mapped to different sub-carriers using the OFDM, wherein the reference signal transmitted in the one sector and the reference signal transmitted in the another sector are distinguished using frequency division multiplexing, wherein a sub-frame for multicast broadcast multimedia service (MBMS) and a sub-frame for unicast are time-multiplexed, wherein, for a sub-frame for unicast, the reference signal transmitted in one sector and the reference signal transmitted in another sector are time and frequency mapped to a different sub-carrier for each of the cells, and wherein, for a sub-frame for MBMS, the reference signal transmitted in one sector and the reference signal transmitted in another sector are time and frequency mapped to a common sub-carrier for multiple of the cells.