Relay Selection Based Space-Time Coding for Two-Way Wireless Relay Networks Using Digital Network Coding

In this paper, we propose a novel decode-and-forward dual-relay selection technique based on Alamouti space time coding for twoway wireless relay networks (TWRNs). The two- and the threephase TWRN protocol are used in the first and second version of the proposed technique, respectively, to exchange the information symbols of the communicating terminals. In order not to waste any power for transmitting information symbols known at any terminal and hence to improve the achievable coding gain, the proposed technique uses the concept of digital network coding in which the transmitted symbols of both terminals are combined at the relays into a symbol of the same constellation. To further improve the reliability of the communication and offer additional coding gain, Alamouti space time coding is incorporated in our technique. Simulation results show a substantially improved bit error rate (BER) performance of the proposed techniques as compared to the the state-of-the art techniques.