A Two-Step Interference Cancellation Technique for a MIMO-OFDM System with Four Transmit Antennas

In this paper a new two-step interference cancellation (IC) technique for an orthogonal frequency division multiplexing system with multiple transmitter and receiver antennas linked over a frequency selective channel is explored. We first utilize a recently proposed type of full code rate space- time block code, which is quasi-orthogonal space-time block code (QO-STBC) scheme to exploit temporal and spatial diversity within a multiuser environment with k co- channel users. We adopt four transmit antennas for each user and two antennas in the receiver. Our scheme has a combined interference suppression scheme based on minimum mean-square error (MMSE) and maximum likelihood (ML) detector, followed by an interference cancellation step. The frame error rate (FER) performance for the proposed algorithm is compared with orthogonal space-time block codes (O-STBC) for two transmitter antennas and extended orthogonal space-time block codes (EO-STBC) in quasi-static and slow fading frequency selective channels. Simulation results show that the proposed method yields a significant improvement in FER performance.