A Maximum Distance Separable Code Assisted AFDM with Joint Spatial-Signal Domain Index Modulation

Affine frequency division multiplexing (AFDM), a novel multi-carrier modulation technique based on chirp signals, is a promising candidate waveform for next-generation high-mobility wireless communications. In this paper, we introduce a focused investigation on AFDM with the context of index modulation (IM), where a maximum distance separable code assisted AFDM with joint spatial-signal domain index modulation (JSSDIM-AFDM) is proposed for enhancing both spectral efficiency and energy efficiency of the AFDM system. The work in this paper mainly focuses on extending IM to multiple physical domains within AFDM, including the discrete affine Fourier transformation (DAFT) domain, the constellation domain, and the spatial domain. It employs maximum distance separable (MDS) codes to optimize multi-constellation assignment and, based on this, designs a three-dimensional index mapping scheme to achieve superior bit error rate (BER) performance. Additionally, We further derive the upper bound on the average bit error probability (ABEP) of the proposed JSSDIM-AFDM scheme through pairwise error probability analysis. Simulation results validate the accuracy of the derived ABEP analysis and demonstrate that the proposed JSSDIM-AFDM scheme achieves superior BER performance compared to AFDM-IM and conventional OFDM-IM schemes in doubly dispersive channels, as well as outperforms SIM-OFDM and MIMO-AFDM systems under various antenna configurations.