Analysis of Asynchronous Distributed Space Time Block Coded System Based on Optimal Relay Selection

This paper investigates the performance of a proposed asynchronous distributed space time block codes with optimal relay selection. In this technique, two best single antenna relays have been selected out of several cooperating relays. The selected relays employ optimised asynchronous linear dispersion codes to form distributed space time block codes which provides advantages of multiple antennas such as capacity as well as diversity gain in distributed system. Further, the signals received at the selected relays are padded with extra delay symbols to make it delay tolerant at the destination in asynchronous environment. This system is called optimal relay selected asynchronous distributed space time block codes (ORS-ADSTBC) in present work. A joint probability density function of the proposed system has been derived which is used to find the closed form expressions of average post processing signal to noise ratio, average bit error rate as well as the ergodic capacity. From the analytical and simulated results, It is observed that the ORS-ADSTBC system outperforms the asynchronous distributed space time block coded for the given performance metrics. It is also observed from the results that the performance further improves by increasing the number of candidate relays for selection.