Recent advances in cooperative communications for wireless systems

Cooperative transmission techniques have been proposed in order to improve the system performance in terms of availability, coverage range and throughput. The cooperative techniques and the smart interactions among the network nodes have been proposed in order to enhance the QoS of their connections and the performance of thewhole network. Radio channel and physical communication characteristics are of paramount relevance to the optimum design of efficient cooperative communications andmobile computing technologies. In recent years, a substantial amount of research effort has been devoted to the development and the design of advanced communication systems that employ the concept of cooperation in order to support highly reliable and spectral efficient transmissions. The focus of this special issue is to present recent advances in cooperative communications and state-of-theart research contributions and practical implementations that advance design of wireless communication systems employing cooperative techniques. Our call for papers attracted numerous submissionsworldwide. After a rigorous review process, we present the following eleven papers. The first paper entitled ‘‘Cooperative Communication with Imperfect Channel Information: Performance Analysis and Optimum Power Allocation’’, by M.B. Abarghouei and A.M.D. Hoseini [1] provides a symbol-error-rate (SER) performance analysis is provided for decode-and forward (DF) and amplify-and-forward (AF) cooperation schemes in wireless networks with imperfect channel information. Closed-form SER formulations for a single relay system with square M-QAM signals under flat Rayleigh fading channel are given and finally the optimum power allocation is determined for the AF andDF cooperation scenarios. In the second paper entitled ‘‘Reputation-based Network Selection Mechanism using Game Theory’’ by R. Trestian, O. Ormond, G.-M. Muntean [2], a theoretical framework for combining reputation-based systems, game theory and network selectionmechanism is presented. Using the repeated Prisoner’s Dilemma game, the authors model the user network interaction as a cooperative game and show that by defining incentives for cooperation and disincentives against defecting on service guarantees, repeated interaction sustains cooperation. In the next paper entitled ‘‘A Distributed and Collaborative Beamforming Algorithm for a Self-Organizing Wireless Sensor Network’’, by M.F. Urso, S. Arnon, M. Mondin,