Spectral Efficiency and BER Analysis of OFDM-IM with M-ary QAM under Rayleigh Fading Channel

Orthogonal Frequency Division Multiplexing (OFDM) is utilized in numerous high data rate wireless systems. It consists of number of closely spaced modulated carriers. However, it has some limitations like high Peak to Average Power Ratio (PAPR), low Spectral Efficiency (SE) and more Inter-Channel Interference (ICI) in frequency selective fading channel. These limitations can be avoided by OFDM through Index Modulation (OFDM-IM). The OFDM block consisting of subcarriers uses the theory of Spatial Modulation (SM). The purpose of OFDM-IM is to make active some subcarriers to transmit M-ary constellation symbols whereas remaining subcarriers is turned off. OFDM-IM is used to attain improved Bit Error Rate (BER) performance with low SE under Rayleigh fading channel. In this paper, OFDM and OFDM-IM with M-ary Quadrature Amplitude Modulation (M-QAM) under Rayleigh fading channel are simulated. In addition, the performance parameters such as Bit Error Rate (BER) and Spectral Efficiency (SE) are determined and analyzed for OFDM-IM and also compared with OFDM.