Adaptive modulation with variable switching thresholds for amplify-and-forward cooperative systems

In this paper, discrete-rate adaptive modulation using variable switching thresholds for amplify-and-forward cooperative systems is evaluated over Rayleigh fading channels. The aim is to improve spectral efficiency of cooperative transmission by maintaining the error rate at acceptable level. The switching thresholds are adjusted using a simple algorithm which depends only on the detection of error in the received block. Results show that the proposed algorithm used to adjust the switching thresholds outperforms the fixed switching thresholds approach in terms of average spectral efficiency.