In this paper, we develop an algorithm to extract the parameters of a multipath model of an UWB channel from measurement/simulated data. To this end, we cast the parameter estimation problem into a standard model selection problem and apply the well known minimum description length principle to solve the model selection problem. Numerical results obtained based on the CM1 and CM2 models suggest that the proposed algorithm is effective.
I. INTRODUCTIONIt is well known that ultra-wideband (UWB) channels have characteristics that are different from traditional wideband channels. This is in fact the main thrust behind many recent research efforts on UWB systems. There have be a significant volume of measurement and modeling works aiming to characterize the UWB channels. An excellent tutorial contribution that summarizes many of the recent such activities can be found in [1].A traditional frequency selective channel is adequately modeled by a tapped delay line with taps spacing set at the duration of the reciprocal of the system bandwidth [2]. In most traditional communication systems, since the symbol rate (or the chip rate for spread spectrum systems) roughly equals the system bandwidth, the received signal approximately consists of replicas of the transmitted pulses, scaled by the channel taps and separated at the tap spacings. This model is usually referred to as the specular multipath model.For a typical UWB channel, a number of measurement studies [1], [3], [4] have shown that the specular multipath model is inadequate. Other physics-based channel models [1], such as those obtained based on ray-tracing analysis, suggest a much finer resolution than the symbol (or chip) spacing in the tapped delay line is needed. Unfortunately many of the physics-based models are not convenient for UWB system design and analysis. As a result, there have been modifications of the standard specular multipath model to better describe the characteristics of an UWB channel.A common modification involves allowing the received pulses at different delays to vary in shape [3]. We will refer to this model as the modified specular multipath model and describe it in detail in Section 11. Some attempts to fit this modified specular multipath channel model to measurement data have been reported in [4], [5]. The subtractive deconvolution approach [6] is employed to extract the model parameters from measurement data. In [4], a known set of