Performance of relay cyclic delay diversity in multicarrier system

In this paper, the performance of a cooperative relaying scheme with cyclic delay diversity (CDD) for an orthogonal frequency division multiplexing (OFDM) system is investigated. The system under consideration consists of multiple single-antenna terminals acting as relays and cooperating to provide spatial diversity. Cyclic shift is introduced at each relay and thus increase the frequency selectivity of relay channels. To exploit a highly selective channel, convolutional code is employed together with OFDM. Simulations demonstrate the bit error performance of the proposed scheme with different numbers of relays as well as performance in flat and frequency selective fading channels. The performance of the system is also compared to conventional multiple-input multiple-output (MIMO) with CDD and a conventional amplify-and-forward (AF) relay system. The results indicate that the proposed scheme provides enhanced performance under various considerations.