近年来，非视距环境下的定位问题研究受到了研究人员的极大关注。本项目考虑非视距环境下基于达到时间差的定位问题。项目研究内容分为三大部分。第一部分考虑完全未知非视距误差统计信息时抑制非视距误差对定位精度的影响，其中根据已知路径状态信息的多少将问题细化为三个研究问题。第二部分主要考虑更为苛刻的条件下的定位问题，即在锚节点存在位置误差时同时抑制非视距误差和锚节点位置误差对定位精度的影响，其中根据已知锚节点位置误差信息的多少将问题细化为两个研究问题。第三部分考虑如何搭建实测系统实现对研究方法性能的实际验证。本课题拟采用的主要方法为凸松弛技术和稳健近似技术，其可行性已在现有文献中得到了充分验证。本课题的研究是开创性、探索性的，由于该研究的前提条件更符合实际情况，因此它对算法从理论应用于实际将起到良好的推动作用，具有重要的理论和实际意义。

Recently, source localization under non-line-of-sight (NLOS) conditions received a lot of attention. This proposal focuses on the time-difference-of-arrival (TDOA) based localization problem under NLOS conditions. The research can be divided three parts. The first part considers how to mitigate the effect of NLOS errors on the localization accuracy without any statistical information of NLOS errors, in which the problem is divided into three aspects according to the knowledge of NLOS path status. The second part considers more hash environments, i.e., there exist errors in anchors' positions. How to mitigate the effects of NLOS errors and the anchor positions errors is the main problem of this part. Similarly, according to the knowledge of the anchor position errors, the problem is divided into two aspects. The third part will focus on the establishment of the testbed, which can be used to verify the efficacy of the proposed methods. To solve the problems stated above, we intend to apply the convex relaxation and robust approximation techniques, whose applicability has been verified in the literature. This work is pioneering and innovative, which is not found in current research. Since this work releases some impractical assumptions, it will facilitate the localization methods to their applications in practice, and hence, this work is of great importance in both theory and practice.