||Recently, wireless positioning has attracted great attention. It has been found useful for many applications. In the first part of this dissertation, we present a proposed threshold based coherent Time-of-Arrival (TOA) estimation scheme for impulse radio UWB systems. The scheme addresses the challenge that in a strong multipath environment, the leading-edge path of a received signal may not be the strongest one, making its detection difficult. The scheme uses a dedicated ranging sequence with good cross-correlation property and a search-back process which considers the count of threshold-crossings to find the leading edge of the received signal. We propose a closed-form approximation for the optimal threshold for restraining the Mean Absolute Error, and verify empirically the accuracy of this approximation by Monte Carlo simulations. We show by simulations that the proposed ranging scheme achieves good performance in short-distance ranging. In the second part of this dissertation, we introduce an indoor geolocation implementation scheme for MB-OFDM system. The scheme combines the Triangulation (TN) positioning method and the Matched filtering ranging algorithm based on the Packet/Frame Synchronization (P/FS) sequence. Simulation results show that this indoor geolocation scheme could achieve reasonable good location performance while only employing simple ranging methods.