Cramér-Rao Lower bound for geolocation in non-line-of-sight environment

Geolocation in an non-line-of-sight (NLOS) environment is an important issue in wireless communications. Several empirical approaches have been proposed in recent years. However, two fundamental questions still remain unanswered: what is the achievable geolocation accuracy in the NLOS environment and how to attain it. In this paper, we derive a closed-form expression of the Cramér-Rao Lower bound (CRLB) for NLOS geolocation, which we believe is new and answers the first question. Its physical interpretation turns out to be very helpful to better understanding of NLOS geolocation mechanism. We discuss some numerical examples based on simulation experiments.