Message Passing-Based Joint Channel Estimation and Signal Detection for OTFS with Superimposed Pilots

TL;DR

This paper introduces a low-complexity message passing-based joint channel estimation and signal detection method for OTFS systems with superimposed pilots, achieving high efficiency with minimal performance loss.

Contribution

It proposes a novel message passing-based receiver with reduced computational complexity for OTFS with superimposed pilots, incorporating a new pilot design for improved channel estimation.

Findings

Significant reduction in computational complexity.

Marginal performance loss compared to existing methods.

Effective channel estimation with optimized pilot design.

Abstract

Receivers with joint channel estimation and signal detection using superimposed pilots (SP) can achieve high transmission efficiency in orthogonal time frequency space (OTFS) systems. However, existing receivers have high computational complexity, hindering their practical applications. In this work, with SP in the delay-Doppler (DD) domain and the generalized complex exponential (GCE) basis expansion modeling (BEM) for channels, a message passing-based SP-DD iterative receiver is proposed, which drastically reduces the computational complexity while with marginal performance loss, compared to existing ones. To facilitate channel estimation (CE) in the proposed receiver, we design pilot signal to achieve pilot power concentration in the frequency domain, thereby developing an SP-DD-D receiver that can effectively reduce the power of the pilot signal and almost no loss of CE accuracy. Extensive simulation results are provided to demonstrate the superiority of the proposed SP-DD-D receiver.