A low-complexity single carrier frequency-domain equalizer(SC/FDE)and diversity combiningmethod for cooperative systems with demodulate-and-forward relaying over frequency-selective channels isproposed.At the relay nodes,linear SC/FDE is adopted and normalized correlation coefficient is intro-duced to derive an equivalent source-to-relay-destination(S-R-D)channel that is highlighted in thisstudy.At the destination,a joint SC/FDE and diversity combining receiver is proposed by utilizing the e-quivalent S-R-D channel.Simulation results demonstrate the superiority of the proposed SC/FDE schemeover the straightforward SC/FDE which ignores the decisions errors at the intermediate relay nodes,
We propose a novel vertical Bell Laboratories layered space-time (V-BLAST) based two-way relayingprotocol that comprises two user terminals and one multi-antenna demodulate-and-forward (DMF) relaystation. We consider the situation when these two user terminals employ different modulation types andinvestigate its detection techniques. The key feature of the detection techniques is that we quantify decisionreliability at the relay station by introducing a so-called normalized correlation coefficient (CORR),rather than having full confidence in demodulation at the relay station. With the assistance of the normalizedconelation coefficient, we develop detection methods at both the relay station and user terminals. Inparticular, we propose a CORR-based ordering algorithm at the relay station which can be applied to detectionfor general V-BLAST architectures. Simulation results demonstrate the superiority of the CORR-basedordering algorithm over the conventional signal-to-noise based ordering algorithm. Finally, wedemonstrate overall error-performance of the V-BLAST-based DMF two-way relaying protocol via simulations.
