Abstract
In this paper, we consider how to improve the capacity of wireless communication networks that employ cooperative diversity techniques. For Amplify and Forward (AF) fixed relaying scheme with adaptive modulation, it has been shown that the scheme can increase transmit diversity but with the expense of a reduction in the spectral efficiency. An efficient Generalized Switching Policy (GSP) for AF incremental relaying with adaptive modulation is proposed to maximize the average spectral efficiency while maintaining the target Bit Error Rate (BER). The performance of the GSP over independent nonidentical Rayleigh fading channels is derived in terms of average spectral efficiency, average BER, and outage probability, then verified by using Monte Carlo simulation. It is shown that the GSP not only outperforms both the conventional direct transmission and the AF fixed relaying but also the Outage Switching Policy (OSP) of the AF incremental relaying proposed recently.