Signal processing model for a transmit-reference UWB wireless communication system

Abstract

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.

Signal model and receiver algorithms for a transmit-reference ultra-wideband communication system

“…We consider a single-user delay-hopped transmit reference system as originally proposed in [6], and develop its signal processing model (as in [1]). In a delay-hopped TR system, the transmitted signal consist of a sequence of chips, each of duration .…”

“…The first pulse is fixed, whereas the second pulse is modulated by the chip value . For the th chip, transmitted at time instant , the chip value is and the selected delay is (following a user-dependent chip sequence and index function), and can be written as (1) Let be the radio propagation channel, and define the convolution between a monopulse and the physical channel as , which we assume to have duration . Ignoring the additive noise (see [14] for this extension) the received signal for the transmitted chip (1) can then be expressed as (2) At the receiver, it is passed through a bank of correlators, each correlating the signal with a delayed version of itself at lags , .…”

“…In [13], a generalization to TR-UWB is proposed where a frame can contain more than two pulses and the receiver utilizes a bank of correlators; our model is usually not applicable to this system unless the transmitted signal is designed such that the received signal is linear in the transmitted symbols. This paper expands on the work in [1] and [2], and proposes a compact data model for a TR UWB system (Section II), including the effect of dispersive channels (Section III). on this, we derive several receiver algorithms (Section IV).…”

Resolving inter-frame interference in a transmit-reference ultra-wideband communication system

“…Similarly, the basic receiver structure consists of a delay, a correlator (multiplier followed by an integrator) to correlate the received signal by the signal delayed by D, and a sampler. Also a variety of receiver structures have been proposed, e.g., using a bank of multiple correlators [2], [3], [4], averaging multiple reference pulse responses into a template that has less noise [5], or splitting up the integration interval into multiple shorter intervals and combining them using weights such as to limit the noise [6], [7].…”

“…In our previous papers [2], [8], we have discussed a TR-UWB scheme that allows D T h , thus lifting the problems associated with implementing long delays, but we still assumed T f > T h . The inter-pulse interference was resolved in the receiver by employing a 1 Technologically, it is not trivial at all to implement such long wideband delays in an IC.…”