中文摘要：

无线电干涉测距（RIR）是无线传感器网络节点定位技术的重要突破，因为它用低成本的简单硬件取得了高精度的测距结果。虽然几个原型系统的经验和最近得到的克拉美罗界对说明RIR的性能都很有意义，对RIR在中低信噪比情况下的测距性能仍然认识有限，这成为RIR广泛应用的主要障碍。试图探索RIR最大似然估计在中低信噪比区间的性能。运用统计信号处理中的区间误差方法（MIE）推导出最大似然估计均方误差与测量信噪比及系统设计参数之间的关系式。大量仿真与实验表明，得到的均方误差表达式能够准确预测整个信噪比区间的MSE性能，因此为RIR的广泛应用扫清了重要障碍。

英文摘要：

Radio Interferometric ranging （RIR） is a breakthrough in the area of wireless sensor networks （WSNs） node localization technique because it achieves high accuracy ranging result with simple, low-cost hardware. Although some experiences from a few prototypes and a recent result about the Cramer-Rao bound （CRB） of RIR sheds some light on its performance, our limited understanding of RIR performance in medium to low signal to noise ratio （SNR） range remains a major obstacle in its widespread adoption. This paper tries to explore the performance of maximum likelihood estimator （MLE） of RIR in medium to tow SNR region. We derive the formula between the mean square error （MSE） of the MLE with respect to the measurement SNR and a few system design parameters employing the method of interval errors （MIE） in the statistical signal processing technique. Extensive simulations and experiments show that the obtained MSE formula is good enough to predict the MSE performance of MLE in the whole SNR re- gion,including the medium to low SNR region, which sweeps out the important obstacle for the widespread adoption of RIR.