Performance of Orthogonal Time – Space Coding Over Rayleigh Fading Channels

Abstract

The demand for mobile communication systems with high data rates has dramatically increased in recent years. Space-Time Block Coding (STBC) is a MIMO transmit strategy which exploits transmit diversity and high reliability. In this thesis presented Orthogonal Space-Time Block Code system (OSTBC) which achieves high through-put and good performance. The main goal of this work is to provide a unified theory of OSTBCs for two and four transmit antennas and one (or more) receives antennas. OSTBCs, provide an elegant encoding and linear decoding technique while offering full diversity benefits in multiple-input multiple-output (MIMO) environments. Our design aims to improve Bit Error Rate (BER) performance, by iteratively choosing code design parameters that minimize the union upper bound on the BER. This design technique is implemented with two cases of 1 or 2 transmit antennas and 1, 2 or 4 receive antennas. Finally, conclude that the use of the proposed method (1x4) reduces the value of BER and the complexity of the system compared with other methods at different values for each of the packet numbers (500, 1000, 2000) packets and frame length (50, 100, 500) symbols so that a simple change in the value of the (Eb/No) of about 1dB (value oscillating between 10 and 11 dB) at 10-4 BER point. The results of the simulation are compatible with what is expected from the use of the OSTBC technique. The simulations show that the Orthogonal STBC design can efficiently reduce the BER and at the same time Reduce signal-to- noise ratio (SNR).