Polling strategies for mobile location estimation in a cellular system

Several techniques have been introduced to estimate the mobile station (MS) location based on the range measurement data polled from a set of base stations (BSs). This paper considers the case when there are polling rate constraints on how often measurements from BSs can be obtained. Polling strategies are proposed. The difference between the strategies is how distributed in time are the BS pollings. An analytic framework is presented to gain the understanding of estimation accuracy by calculating the CRLB (Cramer-Rao lower bound) on the error of the estimation parameters and further applies the CRLB to estimate the location error by extrapolating ahead when no valid measurements are present. The performance of a least square estimator has been compared against this theoretical lower bound.