Min-Max Hamming Distance Considerations for Activation Pattern Design in Index Modulation

Index modulation (IM) has been widely studied showing promising performance over traditional communication systems. Index pattern plays an important role since its activation methodology determines bit error rate (BER), spectral efficiency (SE) and energy efficiency (EE). This work proposes efficient index activation patterns according to a min-max Hamming distance metric for both orthogonal frequency division multiplexing (OFDM) and non-orthogonal spectrally efficient FDM (SEFDM). Simulations of low-density parity-check (LDPC) coded IM systems in both additive white Gaussian noise (AWGN) and frequency selective channels are provided. Results reveal that the proposed index activation patterns in IM systems lead to improved BER and SE compared to that in traditional OFDM systems. Moreover, peak-to-average power ratio (PAPR) distribution results are presented to demonstrate the EE advantage of the proposed IM systems over OFDM systems.