In a distributed spatial diversity wireless system, not all antennas are located at one station as in classical transmit diversity systems, but are dispersed at different, possibly mobile, stations in the network. Transmit diversity is created when the selected stations assist a sender by relaying its information signal to the destination. In this letter, we present an exact average symbol error rate analysis for the distributed spatial diversity wireless system with amplifying relays in a Rayleigh-fading environment. The average symbol error rate formula allows us to clearly illustrate the advantage that the distributed diversity system has in overcoming the severe penalty in signal-to-noise ratio caused by Rayleigh fading. Using simple bounds on the probability of error, we show that the cooperative network presented in this letter achieves full diversity order.Index Terms-Average symbol error probability, cooperative networks, diversity.

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We propose a distributed space-time coding (DSTC) systems based on the Alamouti design. We discuss the limitations in the relay channel of the "out of the box" Alamouti scheme and the additional complexity required to overcome its loss of diversity. Using a bit error rate based antenna selection approach, we design DSTC systems with one regenerative relay that improve on the classical Alamouti scheme when utilized in a two-hop channel. We prove that the proposed one relay DSTC system collects the full diversity of the distributed MISO channel. We also introduce a less complex DSTC system in which the relaying energies depend on the error probabilities at the relays. Numerical results show that the proposed systems perform close to the error probability lower bound obtained by considering error-free reception at the relays.

Abstract-This paper addresses some of the opportunities and the challenges in the design of multi-hop systems that utilize cooperation with one or two intermediate regenerative relays to provide high-quality communication between a source and a destination. We discuss the limitations of using a distributed Alamouti scheme in the relay channel and the additional complexity required to overcome its loss of diversity. As an alternative to the distributed Alamouti scheme, we propose and analyze two Error Aware Distributed Space-Time (EADST) systems built around the Alamouti code. First, using a bit error rate based relay selection approach, we design an EADST system with one and two regenerative relays that rely on feedback from the destination and we show that the proposed system improves on the distributed Alamouti scheme. In addition, we prove that the proposed one relay EADST system collects the full diversity of the distributed MISO channel. Second, we introduce an EADST system without feedback in which the relaying energies depend on the error probabilities at the relays. Numerical results show that both EADST systems perform close to the error probability lower bound obtained by considering error-free reception at the relays.