ON THE STUDIES OF SPACE TIME BLOCK CODES AND IMPLEMENTATION OF UNIVERSAL RELATED SPACE TIME BLOCK CODES

Abstract

This thesis present space time block coding, a new paradigm for communication over fading channels using multiple transmit antennas. Data is 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. Space time block codes are designed to achieve the maximum diversity order for a given number of transmit and receive antennas subject to the constraint of having a simple decoding algorithm. The classical mathematical framework of orthogonal designs is shown to construct space time block codes. It is shown that space time block codes constructed in this way only exist for few sporadic values of n. Subsequently, a generalization of orthogonal designs is shown to provide space time block codes for both real and complex constellations for any number of transmit antennas. These codes achieve the maximum possible transmission rate for any number of transmit antennas using any arbitrary real constellation. Here we have simulated various MRRC & STBC schemes in Matlab enviournment .Then they were used to simulate the relationship between the signal to noise ratio (SNR) and bit error rate (BER). It has been shown that the performance of the 1x1 scheme vs. that of the 2x1 scheme and 1x2 scheme vs. that of the 2x2 scheme by exploiting transmit diversity results in a lower bit error rate even though the same number of receive antennas and transmitted power was used.