Intersymbol/cochannel interference cancellation for transmit diversity systems in frequency selective fading channels

Abstract

As a coding technique designed for use with multiple transmit antennas, space-time coding (STC) has been gaining more and more attention due to its attractive characteristics to provide diversity at the receiver and coding gain over an uncoded system without sacrificing the bandwidth, and increase the effective transmission rate as well as the potential system capacity. This paper presents powerful and computationally linear intersymbol and cochannel interference suppression schemes, considering both zero-forcing (ZF) and minimum mean-square error (MMSE) criteria to combat intersymbol interference (ISI) and suppress cochannel interference (CCI) and obtain diversity gain in a system with the transmit diversity technique using symbol-level space-time block coding (STBC). General linear schemes are derived for the transmit diversity case with two transmit antennas and M receive antennas. The conditions are investigated under which interference can be suppressed perfectly using linear FIR filters in noise-free environments. The binary phase shift keying (BPSK) modulation scheme is assumed to simulate the proposed diversity and interference suppression methods. Numerical results show significant performance improvements compared to the cases without interference suppression.