Adaptive modulation and coding for two-way amplify-and-forward relay networks

In this paper, we introduce an adaptive modulation and coding protocol for all-participate amplify-and-forward relay network systems to achieve a better overall system performance. In the proposed scheme, all the relays are available and have chances to amplify and forward (AF) the signal candidates to the terminals, and for fairness all the relays submit to the same power limitation for the signal amplification. The two source nodes adaptively choose the appropriate modulation and coding scheme based on the information from the feedback channels to ensure that the block error rate (BLER) of the relay system is under the system requirement. Furthermore, we derive closed form expressions for the system performances over Rayleigh Channels, including average spectral efficiency and average BLER. Numerical results show that the analytical results figure out the system performance asymptotically.