LOW COMPLEXITY EQUALIZATION FOR AFDM IN DOUBLY DISPERSIVE CHANNELS

Affine Frequency Division Multiplexing (AFDM), which is based on discrete affine Fourier transform (DAFT), has been recently proposed for reliable communications in high-mobility scenarios. Two low complexity detectors for AFDM are proposed here. Approximating the channel matrix as a band matrix, via placing null symbols in the AFDM frame in the DAFT domain, a low complexity MMSE detection is proposed by means of the LDL factorization. Furthermore, exploiting the sparsity of the channel matrix, we propose a low complexity iterative decision feedback equalizer (DFE) based on maximal ratio combining (MRC), which extracts and combines the received multipath components of the transmitted symbols in the DAFT domain. Simulations results show that both proposed detectors have similar performance, while MRC-based DFE has lower complexity than band-matrix-approximation LMMSE when the channel impulse response has gaps.