On the performance of distributed-STBC in multi-hop wireless relay networks

Clearly, making use of user cooperation transmission technique in a multi-hop wireless network improves its performance in terms of transmission reliability and gives birth to multi-hop wireless relay networks. In this paper, we investigate and evaluate the Bit Error Rate (BER) of multi-hop wireless relay networks employing distributed Space-Time Block Coding (STBC) at many relays´ levels. One relays´ level (to simplify we call it a level) is defined by a set of relay nodes located at the same distance from the source node where the distance is measured by the number of hops. We develop the distributed-STBC multi-hop wireless relay network model for a number of hops greater than 3. Then, we illustrate the impact of the number of hops and the number of relays at each hop on the end-to-end BER. We evaluate the performance of our system by computer simulations. The simulation results show that using a number of relay nodes at one level close to the dimension of the distributed code provides significant BER gains. We also notice that using a number of relay nodes at one level larger than the code dimension does not improve considerably the BER. Moreover, when the distributed STBC is applied to one level, more the level is close to the source, more the obtained BER improvement is pronounced.