Modulation diversity effects in rayleigh fading multipath channels

The wireless channel has characteristics of multipath fading, due to reflection, refraction and scattering. Modulation diversity is a bandwidth-efficient diversity technique that uses rotation, associated with the interleaving between the in-phase and quadrature components of a digital signal constellation. It is intended to mitigate the effects of fading in wireless communications. The research considered a scenario in which multiple paths are simulated, with associated random multiplicative noise and delay. The multipath fading effect is studied in this scenario, and a comparison between the BER values for 4-PSK and 8-PSK transmission is presented, to evaluate the gain provided by the modulation diversity scheme. An analysis concerning optimum rotation angles is performed, considering eight multipath scenarios, including cases with severe fading effect.