Cooperative diversity technique for MIMO-OFDM uplink in wireless interactive broadcasting

OFDMA is regarded as a promising solution for improving the performance of interactive wireless broadcasting systems. Recently, to enhance the performance of OFDMA systems, MIMO techniques have been investigated, and the OFDMA systems have been extended to MIMO architectures. Although transmit diversity is clearly advantageous on OFDMA uplink system in interactive broadcasting, it may not be possible that practical OFDMA system of wireless interactive broadcasting have more than two antennas due to size, cost, or hardware limitations. Cooperative diversity techniques are proposed to overcome the limitations. Cooperative networks aim to utilize the available terminals as a collection of distributed antennas for the transmission of signals from one end of the network to the other. Therefore, this paper focuses on design and performance evaluation of MIMO-OFDMA uplink system with cooperative diversity for wireless interactive broadcasting. For high-rate and reliable transmission, efficient transmission codes are proposed for two transmission cases (one-sided transmission case and two-sided transmission case). And, we present our investigations of the effects of line-of-sight. In the wireless communication environment, line-of-sight is very important to improve the system performance. Under the condition of utilizing the line-of-sight of cooperative partner, the performance of a terminal without line-of-sight can be improved. Taking into account the effects of utilizing line-of sight of cooperative partner, the BER performance is investigated for a MIMO-OFDMA uplink scenario.