Large System Performance Evaluation of the DS/CDMA Relay Channel Using Linear Receivers

This paper considers a relay communication system where cooperative diversity is achieved by spreading the relay transmissions using direct-sequence CDMA (DS/CDMA). We derive expressions for the signal to noise ratio (SNR) employing different receiver filters. The relay signatures are generated according to a random model and the SNR is evaluated in the asymptotic domain, assuming that the number of relays and the signature length grow without bound but with constant ratio. We will also see how the introduction of the signatures, together with the use of the linear minimum square error receiver, effectively transform the relay channel in a set of parallel connections, thus fully exploiting cooperative diversity.