The mobile wireless channel a ords inherent diversity to combat the e ects of fading. Existing code division multiple access (CDMA) systems, by virtue of spread-spectrum signaling and RAKE reception, exploit only part of the channel diversity via multipath combination. Moreover, their performance degrades under fast fading commonly encountered in mobile scenarios. In this paper, we develop new ...

Channel estimation techniques for code-division multiple access (CDMA) systems need to combat multiple access interference (MAI) effectively. Most existing estimation techniques are designed for CDMA systems with short repetitive spreading codes. However, current and next generation wireless systems use long spreading codes whose period is much larger than the symbol duration. In this paper, we...

The views, opinions and/or findings contained in this report are those of The MITRE Corporation and should not be construed as an official Government position, policy, or decision, unless designated by other documentation. Abstract Modems built and analyzed for use on Ultra Wideband (UWB) channels generally use short pulses. Such techniques have been called " impulse radio. " Another suitable c...

The Federal Communications Commission (FCC) mandate for locating the position of wireless 911 callers is fueling research in the area of mobile-positioning technologies. Overlapping multipath propagation is one of the main sources of mobile-positioning errors, especially in fast channel fading situations. In this paper we develop a technique for detecting and providing an estimate of the number...

| Diversity techniques provide a powerful approach to combat fading. Due to the presence of multipath and Doppler shifts, the mobile wireless channel inherently provides diversity that can be exploited using appropriate signaling and reception. While existing CDMA systems exploit only multipath diversity using spread-spectrum signaling, we develop signaling and reception schemes that exploit jo...

Existing subspace-based multiuser timing acquisition algorithms for code-division multiple access systems do not account for the multipath channel eeects satisfactorily. We present a new timing acquisition framework that leverages a canonical representation of the mobile wireless channel to fully exploit the underlying signal structure. The proposed approach promises improved performance based ...

Channel estimation techniques for code-division multiple access (CDMA) systems need to combat multiple access interference (MAI) effectively. Most existing estimation techniques are designed for CDMA systems with short repetitive spreading codes. However, current and next-generation wireless systems use long spreading codes whose periods are much larger than the symbol duration. In this paper, ...

We address the problem of joint estimation of angle and delay of radio wave arrival in a multipath mobile communication channel using knowledge of the transmitted pulse shape function [1-3]. Employing an array of sensors to sample the radio received signal, and subsequent array signal processing can provide the characterization of a high-rank channel in terms of the multipath angles of arrival ...

Diversity and Equalization for MultiGigabit Millimeter Wave Communications over a Sparse Multipath Channel