BER and diversity order analysis of distributed Alamouti´s code with CSI-assisted relays

This paper focuses on average bit error rate (BER) and diversity order analysis of distributed Alamouti´s code in dissimilar cooperative networks with channel state information (CSI)-assisted relays. We first assume that the relays adopt the amplifying coefficient. A lower and an upper bounds of the average BER of the distributed Alamouti´s code are derived. Then we show that the distributed Alamouti´s code only achieves diversity order one when the relays use the amplifying coefficient. Furthermore, in a general cooperative network with more than two relays, we show that the distributed space-time codes only achieve diversity order one as well when the amplifying coefficient is used at the relays. To resolve this problem, we propose a new amplifying coefficient and it makes the distributed Alamouti´s code achieve the full diversity order two.