Performance of multiuser prerake space time block codes in fading channel

Space-time block coding (STBC) is a signaling algorithm utilizing multiple transmit and receive antennas in order to improve the system performance and increase the channel capacity in the presence of fading and interference. This paper introduces Prerake space-time block codes (PRK-STBC) for multiuser direct-sequence code-division multiple-access (DS-CDMA) systems operating in time-division-duplex (TDD) mode. PRK-STBC combines both antenna diversity and temporal precoding. In a DS-CDMA system, the transmit antennas are available to all users at all the time. In a multipath channel, the prerake coding of the transmitted signals results in multipath diversity, without the need of rake receivers at the mobile stations. Hence, only simplified mobile receivers are needed and most of the signal processing is done at the base station. The performance of PRK-STBC is examined in multipath fading. The performance is also investigated against the used number of transmit and receive antennas (up to four transmit antennas and one receive antenna are considered in the simulation).