Using turbo codes with layered space-time coding for MIMO wireless systems

Abstract

Digital communications using multi-input multi-output (MIMO) has recently emerged as one of the most significant technical breakthroughs in modern communications [1] as they offer remarkable spectral efficiency. Among many types of space-time codes, the layered space-time codes (LST) [2] offer a multiplexing gain of ntau (number of transmit antennas) rather than diversity gain offered by space-time block and trellis codes [3]-[5].[6]. Turbo codes [7] are considered novel and revolutionary error-control coding technique because they offer a remarkable performance using an iterative process at the receiver. This iterative process uses a soft input soft-output decoder such as maximum a posteriori probability (MAP) [8] decoder or soft output Viterbi algorithm (SOVA)[9],[10]. In this paper it is proposed to use turbo codes in conjunction with different LST architectures using parallel interference canceller (PIC) iterative receiver. MAP algorithm is used as the soft-input soft-output decoder. Simulation results show a great improvement compared to non-turbo LST systems.