The Performance of Coded Non-Coherent M-ary Orthogonal Keying Based OFDM Systems in a Frequency Selective and Fast Time-Varying Channel

In this paper, we investigate the application of a unipolar non-coherent M-ary orthogonal keying (NC-MOK) for OFDM system that does not require channel estimation and compare its performance with that of bipolar Coherent MOK where for the latter phase information is obtained via pilot-based channel estimation. The performance of the orthogonal M-ary schemes concatenated with Reed-Solomon (RS) codes is investigated over Rayleigh frequency selective and fast time-varying fading channels characterized by high Doppler spreads. Simulation results for the unipolar non-coherent MOK compared with its bipolar coherent counterpart show that the non-coherent MOK performs significantly better in terms of packet error rate at high vehicle velocities. With NC-MOK, a performance gain is achieved as well as a simpler receiver implementation.