Time-of-flight-based ranging among transceivers with different clocks requires protocols that accommodate varying rates of the clocks. Double-sided two-way ranging (DS-TWR) is widely adopted as a standard protocol due to its accuracy; however, the precision of DS-TWR has not been clearly addressed. In this paper, an analytical model of the variance of DS-TWR is derived as a function of the user-programmed response delays, which is then compared to the Cramer-Rao Lower Bound (CRLB). This is then used to formulate an an optimization problem over the response delays in order to maximize the information gained from range measurements. The derived analytical variance model and optimized protocol are validated experimentally with 2 ranging UWB transceivers, where 29 million range measurements are collected.

翻译：基于飞行时间在两台具有不同时钟的收发机之间进行测距时，需要采用能够适应时钟频率变化的协议。双边双向测距（DS-TWR）因其准确性而被广泛采用作为标准协议；然而，DS-TWR的精度尚未得到明确阐述。本文推导了DS-TWR方差的解析模型，将其表示为用户可编程响应时延的函数，并与克拉美-罗下界（CRLB）进行了比较。在此基础上，构建了一个关于响应时延的优化问题，旨在最大化从测距测量中获取的信息量。通过两个测距超宽带（UWB）收发机进行的实验（收集了2900万个测距测量样本）验证了所提出的解析方差模型及优化协议。