Rate-Splitting--Inspired Bistatic OFDM-ISAC

TL;DR

This paper introduces a rate-splitting inspired framework for uplink bistatic OFDM-ISAC, improving interference management and robustness to Doppler effects through joint power allocation and a staged receiver design.

Contribution

It proposes a novel RS-inspired transmission scheme and a joint power allocation method tailored for OFDM-ISAC, addressing interference and Doppler challenges.

Findings

Outperforms NOMA-inspired baselines in interference management.

Enhances robustness to Doppler-induced ICI.

Provides a tractable framework for joint power allocation.

Abstract

Achieving effective uplink bistatic ISAC over an OFDM waveform gives rise to challenging interference structures. These are mostly due to unequal direct- and echo-path contributions and Doppler-induced ICI, rendering orthogonal resource separation and fixed SIC strategies inadequate. To address this problem, we propose a RS-inspired framework where the transmitter splits each communication message into a robust and a supplementary stream, which are jointly superposed over a sensing signal. Furthermore, we present the design of a staged sensing-communication receiver. Based on this framework, we derive tractable per-subcarrier SINR expressions and establish the relation between sensing accuracy and communication reliability based on the Fisher information. Building on these, we formulate a joint power-allocation problem for SE maximization under sensing-performance and power constraints. The resulting non-convex formulation is solved using convex surrogates and fractional programming. Numerical results demonstrate that, compared to NOMA-inspired baselines, the proposed framework provides more effective IFI management and improved robustness to Doppler-induced ICI.