Asynchronous Time Difference of Arrival Positioning System

This paper presents a newly proposed asynchronous time difference of arrival (A-TDOA) positioning system. Two major challenges for accurate location finding in indoor environments are the fine time resolution and high accuracy time synchronization. This paper proposes a new positioning method that resolves the time synchronization difficulty by measuring the time difference of arrival at a single anchor node. Unlike conventional time of arrival (TOA) and time difference of arrival (TDOA) based methods, no synchronization is required between a target node and any anchor node, nor is required among anchor nodes. Therefore, the A-TDOA system avoids stringent synchronization between target and anchor nodes, and it eliminates the need of back-bone cables for anchor nodes synchronization, which makes it highly practical and can be easily implemented. In addition, two novel algorithms are proposed to expand the application of the A-TDOA positioning system, one is a hybrid positioning algorithm that combines semidefinite programming (SDP) with a Taylor series method to achieve global convergence as well as superior estimation accuracy, and the other is a constrained least-squares method that has the advantage of low complexity and fast convergence while maintains relatively good performance.