Achieving Higher-Rate Full-Diversity in Cooperative Relay Networks using Extended Orthogonal Space Time Block Codes (EO-STBC)

Significant and difficult technical challenges are imposed today on wireless networks, for example increasing capacity and reliability to achieve full data rate, full propagation diversity, comprehensively improve transmission synchronization, communications reliability, outage behaviour, and the overall system performance. Therefore, the next-generation wireless communication systems are designed to fulfil these requirements. Cooperative relay network is one of the methods which can utilize spatial diversity to improve the transmission capacity and provide reliable links throughout the wireless system environment. The design and analysis of various distributed space-time block coding schemes for cooperative relay networks is conducted in this work. Rayleigh frequency flat fading channels are assumed to model the channels between the relay nodes and destination nodes in the wireless networks. The main contribution of this doctoral research is to exploit the extended orthogonal space-time block coding (EO-STBC) to provide a higher data rate, full diversity, and consequently, increase the data throughput capability for a variety of two-hup cooperative wireless relay networks in one and bidirectional ways.
Firstly, the end-to-end bit error rate (BER) performance of cooperative wireless communication networks based on distributed orthogonal space-time coding (DOSTBC), distributed extended orthogonal space-time block coding (D-EO-STBC) for the decode-and-forward (DF) & Amplify-and-forward (AF) relaying protocols, were studied and analysed. The results confirm that the best BER performance is achieved by the system with four relays based on D-EO-STBC and DF techniques. On the other hand, the best BER performance is achieved by the closed-loop MIMO model based on D-EO-STBC and AF techniques. In addition, two distributed extended orthogonal space-time block Codes (D-EO-STBC) schemes for one-way and two-way transmissions are proposed. Both schemes achieve full-transmission diversity and improve the performance of the system and achieve full-data rate in the bidirectional way transmission. Moreover, the second scheme has the advantage of minimizing the decoding complexity at the relay nodes. Finally, two wireless cooperative networks for one-way bidirectional transmissions utilizing a relay selection (RS) technique are considered, where the outage probability of the system under the channel environment conditions is examined. The RS is assigned to choose the optimum 4-relays from K-available relays to improve the performance of the proposed scheme. Probability density function (PDF) and cumulative density function (CDF) have been theoretically used to compute the outage probability of the relay paths in Rayleigh fading channels. The proposed distributed extended orthogonal space-time block coding (D-EO-STBC) with RS in [108] provides significant improvement in the outage probability as compared to the conventional D-EO-STBC.