Application of the Combination Scheme of PAPR Reduction and Predistortion Techniques in Cooperative Communication with AF Protocol using the Relay Selection Strategy

In this paper, we investigate the combination scheme of PAPR reduction and predistortion techniques in cooperative communication system with amplify and forward (AF) protocol using the relay selection strategy. OFDM has a major drawback which is the high peak power value. Then, the combination scheme of reduction technique with the Selective Mapping (SLM) scheme and Hammerstein model as a predistorter is applied to overcome this problem. Those combination scheme can reduce the PAPR value while increasing the linear region of the system. So the nonlinear distortions can be removed by the predistorter before the signal enters the nonlinear high power amplifier (HPA) at the source. Rapp model is used as memoryless nonlinear PA at relays, and the inverse of the Rapp model is used as the predistortion technique. The use of relays as virtual antennas in cooperative communication systems can be implemented for 4G or 5G networks in future research, but it requires a large bandwidth. So by implementing a relay selection strategy, bandwidth efficiency will increase because only the best-selected relay will forward information from the source to destination. The performances of the scheme in the cooperative communication system are expressed in bit error probability or BER values. From the simulation results would be shown that in the combination scheme, the predistortion technique improves the BER values, while the SLM PAPR technique has no significant impact on the BER values. The application of both the predistortion techniques at source and relay results in the best performance, at the same BER value, the system improved by 1.8 dB compared to implementation at source only, 6.2 dB compared to implementation at relay only, and 7.2 dB compared to without implementation of predistortion technique.