This paper presents a signal processing model for the delay-hopped transmit-reference ultra widehand communications system introduced by Hoctor and Todinson. In that paper, a single-user receiver based on a bank of correlators and a sliding window integrator was proposed. However, the radio propagation channel also introduces correlations, which have a significant effect not taken into account by the Hoctor-Tomlinson receiver. Here we propose an accurate signal processing model for the transmit-reference system, including the effect of the propagation channel, as well as an algorithm to estimate the resulting effective channel coefficients.

Abstract-In transmitted reference ultra-wideband (TR-UWB) systems and differential transmitted reference (DTR-UWB) systems, the performance is, besides to noise, determined by interference among pulses due to the dispersive multipath radio channel (interframe interference). The multiple access interference is also heavily influenced by multipath propagation. As a first step towards the analysis and optimization of such systems, this paper analyzes statistically the response of the pulse-pair correlators including integrate and dump circuitry, which are the basic building block of TR-UWB receivers, to desired and un-desired pulse-pairs. Results are given in terms of basic channel parameters like RMS delay spread and Ricean K-factor. As an example for the application of our analysis, we present a novel multiuser DTR-UWB system.

Abstract-A communication system based on transmit-reference (TR) ultra-wideband (UWB) is studied and further developed. Introduced by Hoctor and Tomlinson, the aim of the TR-UWB transceiver is to provide a straightforward impulse radio system, feasible to implement with current technology, and to achieve either high data rate transmissions at short distances or low data rate transmissions in typical office or industrial environments. The main contribution in this paper is the derivation of a signal processing model that takes into account the effects of the radio propagation channel, in particular, for the case where the two pulses in a doublet are closely spaced. Several receivers based on the code-division multiple-access-like properties of the proposed model are derived, and the performance of the algorithms is tested in a simulation.Index Terms-Impulse radio, receiver algorithm, signal processing, transmit-reference (TR), ultra-wideband (UWB).

This paper presents an approach to multi-user

This paper proposes a method to simultaneously track symbol timing, carrier phase and frequency offset errors for an OFDM (Orthogonal Frequency Division Multiplex) communications system. Each of these three offsets rotates the OFDM symbol constellations in a conspicuous way. Their characters are illustrated and it is explained how can the receiver DFT (Discrete Fourier Transform) outputs be used for estimation. The method presented is based on the rotational impact of offsets on the individual sub-carriers. The technique employs the joint-ESPRIT (Estimation of Signal Parameters via Rotational Invariance Techniques) algorithm and can be used for data-aided and blind estimation, as well as for the combination of these two. Assuming a prior initial acquisition, it uses the information contained in the phase rotation between the correct and the received sub-symbols after the DFT.