Combining Co-operative Diversity in Wireless Communication

Abstract

Wireless devices cannot employ Multiple Input Multiple Output (MIMO) due to hardware or size limitation. Wireless device should replicate their single antenna virtually to act like MIMO system for better performance. This process is possible through a new system known as co-operative communication. In this system, the terminal or nodes combined to transmit the signals to follow an antenna array and form the diversity. Diversity is nothing but transfer of different samples of signal on independent channels. The users can increase their effective quality of service through the co-operative diversity. In this paper, diversity was realized through a third station other than the sender and the receiver. The destination gets the signal via this relay and also gets the signal directly from the source without the relay. The two signals were combined using different combining techniques like Maximum ratio combining, equal gain combining, and selective combining. In this paper the performance of these combining methods were examined. At the relay two relay protocols were examined along with the combining methods. In addition to this paper explained how the diversity was achieved by implementing the Alamouti scheme block coding in wireless relay along with amplify and forward protocol. Analysing the performance decode and forward protocol scheme with the repetition codes. For this a three node terminal system was considered with one source, one relay and one destination. The performance was simulated over the Rayleigh channel.