Subchannel division adaptive resource allocation technique for cooperative relay based MIMO/OFDM wireless communication systems

In this paper, we propose cooperative division relay based allocation technique jointly with adaptive bit/power loading for multiple input multiple output/orthogonal frequency division multiplexing (MIMO/OFDM) system. In this cooperative division technique, the transmitted stream of bits is divided into two parts. The first part is sent directly from the source to the destination, whereas the second part is relayed to the destination through an indirect link. The sub channel division is jointly optimized with adaptive bit/power loading among different sub channels to maximize the overall MIMO/OFDM received signal in the relay based system according to the channel state information (CSI). The bit error rate (BER) performance using this cooperative division technique is presented and compared with non cooperative one. The use of this type of cooperative technique in relay based MIMO/OFDM system has shown high BER performance improvement. Such improvement comes from the fact that this technique jointly with adaptive bit/power loading, in relay based system, enables us to exploit the inherent system diversities in the frequency, space, and time to maximize the system power efficiency, and to guarantee the fulfillment of the required quality of service (QoS) including BER and transmission rate. It is noticed that the advantage of cooperation in terms of BER increases as the order of MIMO system increases.