Bit error probability and capacity analysis for OSTBC over triply selective fading channels

Abstract

In this paper, orthogonal space time block coding (OSTBC) in multiple input multiple output (MIMO) systems is employed. The considered channel is the triply selective fading channel (the spatially correlated obeying Kronecker model, time varying and frequency selective). The precoded OSTBC probability of error over triply selective Rayleigh fading channels is investigated for phase shift keying/quadrature-amplitude modulation (PSK/QAM) and compared with the conventional STBC system. A closed analytical form expression for the OSTBC ergodic capacity in triply selective fading channels is derived with unknown channel state information at the transmitter (CSIT) due to time varying. The effect of inter-symbol interference (ISI) is also investigated in the case of uniform and non-uniform spatially correlation fading channels. The capacity of MIMO systems with the estimated CSIT at low SNR regime is analyzed and compared with the capacity of unknown CSI at the transmitter in frequency selective Rayleigh fading channel. It has been shown that when the CSIT is unknown, the capacity of MIMO systems is improved by increasing the number of receiving antennas. Yet, in the case of estimated CSIT, it has been shown that the ergodic capacity depends on the estimation error regardless the number of transmitting or receiving antennas.