Evaluation of the improvement in the position estimate accuracy of UMTS mobiles with hybrid positioning techniques

In a wireless communication network, the position estimation of a given user equipment is usually obtained by the combination of angle and delay measurements of one or more radio links between that user equipment and one or several base stations. This paper focuses on the performance of an approximate maximum likelihood position estimator in the presence of non-zero cross-correlations between measurements. This issue becomes specially relevant in hybrid positioning techniques because angles and delays of the same radio link are combined and, in consequence, the usual assumption of uncorrelation between measurements does not hold.