Abstract
This paper investigates the amalgamation of affine
frequency division multiplexing (AFDM) with sparse code multiple access (SCMA), termed as AFDM-SCMA, to facilitate massive
connectivity in high-mobility scenarios. We start by introducing
the basic principles of SCMA and AFDM systems and then
present the proposed AFDM-SCMA system with multiple input
and multiple output (MIMO) for both downlink and uplink
channels. A two stage detector is proposed for the multi-user
detection of the downlink channels. Additionally, to reduce the
detection complexity and exploit the channel sparsity, we propose
an expectation propagation algorithm (EPA)-aided low complexity receiver for uplink channels. Through numerical simulations,
we validate the enhanced performance of the proposed AFDMSCMA systems compared to conventional orthogonal frequency
division multiplexing-empowered SCMA (OFDM-SCMA) systems in terms of error rate performance.