信号处理2026，Vol.42Issue(6)：871-883,13.DOI:10.12466/xhcl.2026.06.008
基于概率星座码本优化的OFDM通感一体化低慢小目标感知方法
Probabilistic Constellation Codebook Optimization for OFDM-Based ISAC for Low-Slow-Small Target Detection
摘要
Abstract
Reusing communication signals for environmental sensing is an effective approach to reducing hardware com-plexity and improving spectrum efficiency in integrated sensing and communications(ISAC)systems.Among various candidate waveforms,orthogonal frequency division multiplexing(OFDM)is widely considered a key solution to communication-centric ISAC owing to its mature engineering implementation and favorable spectral characteristics.However,practical communication systems commonly employ non-constant modulus quadrature amplitude modulation(QAM),which introduces symbol randomness.In sensing processing based on matched filtering(MF)and reciprocal filtering(RF),this randomness affords elevated sidelobe levels,increased background fluctuations,and degraded pa-rameter estimation accuracy.These effects become particularly severe for low signal-to-noise ratios and significantly limit the detection performance for low-altitude,slow-moving,and small targets.To address these challenges,herein we develop a comprehensive sensing model for OFDM-based ISAC signals,and for the first time,establish the intrinsic mapping between channel-domain and parameter-domain estimation,systematically revealing the effects of modulation symbol randomness on sensing performance under different time-frequency filtering structures.Based on this analysis,a probabilistic constellation shaping(PCS)optimization framework is proposed for MF and RF.By optimizing the input probability distribution of constellation points,the proposed method maximizes mutual information under sensing and power constraints.Therefore,communication and sensing performance can be flexibly balanced without modifying the OFDM physical layer parameters or constellation set.The simulation results show that the proposed approach signifi-cantly enhances sensing accuracy with only minor communication rate loss.Field experiments on low-altitude,slow-moving UAV targets further validate its effectiveness in realistic environments.关键词
通感一体化/正交频分复用信号/概率星座整形/时频滤波Key words
integrated sensing and communications/orthogonal frequency division multiplexing signal/probabilistic constellation shaping/time-frequency filtering分类
信息技术与安全科学引用本文复制引用
徐婧婧,杜振,王杰,王钟斌,夏树强,尉志青..基于概率星座码本优化的OFDM通感一体化低慢小目标感知方法[J].信号处理,2026,42(6):871-883,13.基金项目
国家自然科学基金(62301264) （62301264）
江苏省自然科学基金(BK20230416) （BK20230416）
中兴通讯研究基金(IA20240701009) The National Natural Science Foundation of China(62301264) （IA20240701009）
Natural Science Foundation of Jiangsu Province(BK20230416) （BK20230416）
ZTE Industry-University-Institute Cooperation Funds(IA20240701009) （IA20240701009）
