Iterative Equalization-Decoding Algorithm with Coded OTFS for LEO Satellite Communications

To satisfy the stringent reliability requirements of next-generation wireless systems, low Earth orbit (LEO) satellite communication receivers must address the challenges posed by doubly-selective (time frequency) fading in satellite-terrestrial links, while ensuring seamless global connectivity. In this paper, we propose a novel iterative equalization-decoding algorithm integrated with coded orthogonal time frequency space (COTFS) to overcome the reliability limitations of conventional receivers. By leveraging the sparse channel estimation results obtained from COTFS signal processing in the delay-Doppler domain, we design a distributed equalization-decoding algorithm coupled with pathwise maximum ratio combining (MRC) to effectively mitigate interference. To address error propagation inherent in conventional iterative detection and balance reliability with complexity, we integrate ordered likelihood decoding (OLD) with a lowcomplexity implementation. Simulation results demonstrate that the proposed algorithm achieves superior reliability compared to conventional COTFS receivers.