The Influence of ICI for High Mobility Adaptive OFDM Systems in Nakagami-M Fading Channel

Orthogonal frequency division multiplexing (OFDM) has been the leading multi-carrier modulation technology for radio communication. In this article, we studied the impact of power transmission and rate adaptive modulation on the average spectral efficiency (ASE) of OFDM systems by using square M-ary QAM (MQAM) under instantaneous bit error rate (BER) and average power constraints in Nakagami multipath fading (NMF) channel. We obtained closed-form expressions for the capacity when this adaptive scheme is used in NMF channel and inter-carrier interference (ICI) at the high mobility. Simulation result has indicated that the adaptive modulation has optimistic increase in ASE versus the non-adaptive modulation.