Cooperative diversity represents an effective way of combating multipath fading through inter-terminal cooperation in wireless networks. In this letter, we propose a new participation strategy that increases the chance of cooperation and present the closed-form expression for outage probability. Numerical results demonstrate that new participation strategy improves the outage performance.

This paper proposes cooperative coding using cyclic delay diversity (CDD) for OFDM systems. The cooperative diversity is combined with channel coding while CDD is applied to the cooperative transmission of the multiple relays to improve the beneficial effects of the cooperating relays. Analyses of frame error probability (FEP) and the average channel power of the proposed scheme are shown. Simulation results show the frame error rate (FER) of the proposed scheme. The proposed scheme provides not only a simple code design and low system complexity compared to conventional space-time processing, but better FER and diversity gain compared to direct transmission and conventional cooperative coding without CDD.

Diagonally weighted space-time trellis codes using one-bit feedback of channel information are considered. We derive performance criteria for designing STTC and weighting matrix in perfect feedback channel. A simple modification of conventional STTC using unitary rotation is proposed and some modified STTCs are found through computer search. Simulation results show that the modified STTCs achieve the improved performance over a wide range of feedback channel condition.