The time of arrival (TOA)-based localization techniques, which need to estimate the delay of the line-of-sight (LoS) path, have been widely employed in location-aware networks. To achieve a high-accuracy delay estimation, a number of multiband-based algorithms have been proposed recently, which exploit the channel state information (CSI) measurements over multiple non-contiguous frequency bands. However, to the best of our knowledge, there still lacks an efficient scheme that fully exploits the multiband gains when the phase distortion factors caused by hardware imperfections are considered, due to that the associated multi-parameter estimation problem contains many local optimums and the existing algorithms can easily get stuck in a "bad" local optimum. To address these issues, we propose a novel two-stage global estimation (TSGE) scheme for multiband delay estimation. In the coarse stage, we exploit the group sparsity structure of the multiband channel and propose a Turbo Bayesian inference (Turbo-BI) algorithm to achieve a good initial delay estimation based on a coarse signal model, which is transformed from the original multiband signal model by absorbing the carrier frequency terms. The estimation problem derived from the coarse signal model contains less local optimums and thus a more stable estimation can be achieved than directly using the original signal model. Then in the refined stage, with the help of coarse estimation results to narrow down the search range, we perform a global delay estimation using a particle swarm optimization-least square (PSO-LS) algorithm based on a refined multiband signal model to exploit the multiband gains to further improve the estimation accuracy. Simulation results show that the proposed TSGE significantly outperforms the benchmarks with comparative computational complexity.
Fundamental Limits and Optimization of Multiband Sensing
多频带传感是一种利用多个非连续频段实现高分辨率目标感知的技术。在本文中，我们调查的基本限制和优化的多波段传感，重点是与时间延迟的基本限制。我们首先使用Dirichlet核导出具有紧凑形式的Fisher信息矩阵（Fisher information matrix，CRB），然后在简化情况下导出延迟分离的Cramer-Rao界（CRB）的封闭形式表达式，以揭示有用的见解。然后，一个度量称为统计分辨率限制（SRL），提供了一个分辨率限制调查延迟分辨率的基本限制。基于CRB和Ziv-Zakai界（ZZB），研究了时延估计的基本极限。在此基础上，分析了频段孔径和相位畸变对多频段传感系统性能极限的影响。我们制定了一个优化问题，以找到最佳的系统配置在多波段传感系统的目标是最小化延迟SRL。为了解决这个非凸约束问题，我们提出了一个有效的交替优化（AO）算法，迭代优化变量使用逐次凸逼近（SCA）和一维搜索。仿真结果验证了该算法的有效性。
Bistatic Delay-Doppler Sensing for 3D Target Localization in Distributed Wi-Fi Systems
Interdisciplinary Centre for Security, Reliability and Trust (SnT), University of Luxembourg（卢森堡大学安全、可靠性与信任跨学科中心）；IEE S.A.（IEE公司）；Télécom SudParis, Institut Polytechnique de Paris（巴黎理工学院苏德帕里斯电信学院）
Joint Channel Estimation and Localization in Pinching-Antenna OFDM Systems: The Blessing of Multipath
School of Information Science and Technology, Southwest Jiaotong University（西南交通大学）；School of Engineering and Mathematical Sciences, La Trobe University（乐卓博大学）
