Robust time-delay and amplitude estimation for CDMA location finding

Wireless location finding is gaining considerable attention in the field of wireless communications. This is due to a recent USA government mandate for wireless service providers to locate users in emergency situations within a high precision. In this paper, we introduce a new estimation scheme for the time and amplitude of arrival of a code division multiple access signal transmitted over a single-path Rayleigh fading channel for location finding applications. Optimum choices of the estimation scheme parameters are derived. The paper also presents a new noise and fading bias equalization technique for amplitude of arrival estimation that enhances its estimation precision significantly. The paper gives simulation and field trial results that show significant robustness of the proposed scheme to high noise levels and fast channel fading.