Performance Evaluation of Multi Stage Receivers for Coded Signals in MIMO Channels

In this paper we evaluate the performance of a multi stage receiver for coded signals (using space time block codes) when MIMO (multi input multi output) channels are employed. This provides a new paradigm for transmission over Rayleigh fading channels where scattering phenomenon is a major obstruction. At the transmitter side data encoded using a space-time block code, and the encoded data is split into n streams which are simultaneously transmitted using n transmit antennas. The received signal at each receive antenna is a linear superposition of the n transmitted signals perturbed by noise. At the receiver side we employ different equalization and detection techniques to obtain optimum BER. The detection algorithms that we have tried out are zero-forcing, MMSE, maximum a posteriori, maximum likelihood, nulling and cancellation using QR factorization and iterative MMSE. We review the encoding and decoding algorithms for various codes and provide simulation results demonstrating their performance. It is shown that using multiple transmit antennas and space-time block coding provides remarkable performance at the expense of almost no extra processing. It is also seen different detecting algorithms are optimized for different fading environments.