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In this paper, the end-to-end bit error performance of a dual-hop (DH) energy harvesting (EH) amplify-and-forward/decode-and-forward (AF/DF) system is investigated. In this system, the source communicates with the destination over an intermediate relay when the direct link between the source and the destination is in deep fade. The channels are assumed to be exposed to Nakagami-m fading and all nodes are equipped with one antenna. The relay uses power splitting (PS) and time switching (TS) relaying protocols to harvest energy and uses it to forward the decoded signal or to transmit the amplified version of the received signal to the destination. The bit error probabilities of the considered DH-AF and DH-DF systems are analytically derived for both EH protocols and their performances are comparatively evaluated. Moreover, a system optimization is performed to maximize the bit error rate (BER) performance. For the TS mode, a list of mixture of modulations is provided for different spectral efficiency values and different time allocation parameters. Our comprehensive results on the BER performance of AF- and DF-aided DH networks with EH in the relay, provide basic guidelines for the design of the future DH-EH systems.

In this study, the authors propose novel cooperative spatial modulation (SM) systems with two main relaying techniques [amplify-and-forward (AF) and decode-and-forward (DF)], where all nodes have multiple transmit and/or receive antennas. Most of the studies in the literature of cooperative SM systems, which combine the advantages of cooperative communications and SM systems, consider only the space shift keying (SK) scheme with single receive/transmit antenna at relay and destination. Since the error performance of SM highly depends on the number of receive antennas and more flexible cooperative communications systems can be obtained by using SM with multiple antennas, it is essential to investigate multiantenna cooperative SM systems. They derive analytical expressions of the average bit error probability for both the newly proposed cooperative SM-DF and cooperative SM-AF systems and validate with the computer simulation results. Furthermore, they present the bit error rate comparison of considered systems with classical M-ary phase SK/quadrature amplitude modulation cooperative systems. Computer simulation results indicate that multiple antennas cooperative SM systems provide better error performance than classical cooperative systems for both relaying techniques.

M-PSK cooperative trellis codes are proposed for two-user coordinate interleaved coded cooperation operating over quasistatic Rayleigh fading channels. The coding approach properly combines cooperative and modulation diversity techniques to take their full advantage. Two selective cooperation schemes are considered related to whether users know the cooperation status or not. Upper bounds on the pairwise error probability of the considered schemes are derived for each cooperation case which lead to new code design criteria. Based on these criteria, 4-, 8-, 16- state QPSK and 8-, 16- state 8PSK cooperative trellis codes are obtained by means of exhaustive computer search. The error performance evaluation of the new codes by computer simulations shows that they outperform the corresponding best space-time codes used in cooperation with coordinate interleaving. Copyright (c) 2009 O.Oruc and U. Aygolu.