Input-Output Relation and Low-Complexity Receiver Design for CP-OTFS Systems with Doppler Squint

TL;DR

This paper investigates the Doppler squint effect in OTFS systems, derives the input-output relation considering DSE, and proposes a low-complexity receiver design that improves performance in high-mobility scenarios.

Contribution

It introduces a practical OFDM-based OTFS system model with DSE, analyzes CP length, and develops a low-complexity receiver leveraging channel matrix properties.

Findings

DSE significantly impacts OTFS performance.

The proposed receiver effectively mitigates DSE effects.

Simulation results show improved detection accuracy.

Abstract

In orthogonal time frequency space (OTFS) systems, the impact of frequency-dependent Doppler which is referred to as the Doppler squint effect (DSE) is accumulated through longer duration, whose negligence has prevented OTFS systems from exploiting the performance superiority. In this paper, practical OFDM system using cyclic prefix time guard interval (CP-OFDM)-based OTFS systems with DSE are adopted. Cyclic prefix (CP) length is analyzed while the input-output relation considering DSE is derived. By deploying two prefix OFDM symbols, the channel estimation can be easily divided into three parts as delay detection, Doppler extraction and gain estimation. The linear equalization scheme is adopted taking the block diagonal property of the channel matrix into account, which completes the low-complexity receiver design. Simulation results confirm the significance of DSE and the considerable performance of the proposed low-complexity receiver scheme considering DSE.