Bit-wise Detection for OTFS Modulation via Message Passing Algorithm

Abstract

The orthogonal time frequency space (OTFS) modulation as a promising signal representation attracts growing attention for integrated sensing and communication. This paper devotes to signal detection for OTFS system. Notice the characteristics of high dimension and sparsity of OTFS channel, we propose a bit-wise message passing (MP) algorithm to support Soft-Input Soft-Output detection. We leverage the channel sparsity to simplify the factor graph, and approximate the discrete messages with continuous Gaussian distribution to facilitate message updating. Simulations in various cases validate the outperformance of the proposed algorithm contrast to existed symbol-wise MP and linear detectors.