Sequential Iterative Cramer-Rao Bound Containing NLOS Signal in Cooperative Localization

Cramer-Rao Lower Bound (CRLB) has been extensively utilized for wireless location network for its concision and closed form property. In this paper, a generally analytical method and a sequential iterative CRLB (I-CRLB) is proposed and derived for multi-node collaborative scenario with consideration of NLOS distance measurements. According to positively biased property, NLOS range error is fitted by real measurements data, and modeled as Gamma distribution. Based on Gamma distribution, the I-CRLB is obtained by the joint probability of the measurements and system states. This bound is iteratively calculated by chain rules and presents the theoretical accuracy limit of any position estimators under NLOS environments.