High resolution estimation of the time of arrival for GSM location

Location services in cellular systems have become more and more important. One of the reasons is the Federal Communications Commission´s (FCC) requirement to determine the position of a mobile user within an root-mean-square accuracy of 125 meters. A number of location techniques are based on the estimation of the time of arrival (TOA) or the time difference of arrival (TDOA) of the line-of-sight (LOS) signal component. However, due to multipath propagation and the limited bandwidth available in GSM or in other narrowband systems, an accurate TOA-estimation using conventional methods is hardly achievable. In this paper TOA-estimations using the modified-least-squares-Prony (MLS-Prony) and the Root-MUSIC techniques are presented. Moreover, the performance of both techniques is evaluated through simulations of a GSM transmission over different multipath channels