UWB Channel Fading Statistics and Transmitted Reference Communication

PhD Student 
Jacobus Romme
Research Area

 

 After the regulation of Ultra-wideband (UWB) by authorities worldwide starting in the US in 2002, many initiatives were launched to investigate the potential of the radio technology for commercial applications. Currently, the first commercial products arrive on the market, which provide broadband short-range communication. Although the first products are on the market, many questions remain to be unanswered. In this thesis, we hope to have answered some of these open questions. It is well-known that UWB is inherently robust against small-scale-fading (SSF) that arises in multipath environments, due to its large signal bandwidth. However, no model with a physical interpretation exists that relates the variations of received signal strength to the signal bandwidth and general channel parameters, like e.g. the average channel power delay profile. In this thesis, such a model is presented that allows for such a tradeoff analysis, relating the average power delay profile parameters and signal bandwidth to the statistical properties of the SSF. Additionally, it is shown how the uncoded and coded BER of BPSK modulation can be computed in a closed-form for a given average power delay profile parameters and signal bandwidth. As stated before, UWB communication is inherently resilient against SSF. Unfortunately, this advantage does not come without a price. Coherent receivers become rather complex in the UWB case. In 2002, Tomlinson and Hoctor proposed to combine Transmitted Reference (TR) signaling with an autocorrelation receiver (AcR) for UWB communications, to dispose of the need for channel estimation. Due to the non-linear structure of the AcR, little was known with respect to its behaviour in various situations. This thesis aims to provide better insight in the behaviour of TR UWB systems. Not only is the principle of TR UWB communication explained, also several extensions to the TR principle are proposed, which relief some of its drawbacks. Additional, novel interpretations for the TR UWB systems will be presented, which explain the behaviour of {TR} systems e.g. in the presence of inter-symbol-interference. After understanding the behaviour of TR UWB systems, the design of a high-rate TR UWB system is presented. The design aim is to obtain a system that supports data-rates up to 100 Mb/s, while occupying 1 GHz of bandwidth. Using a combination of trellis-based equalization, multiband processing, turbo equalization and turbo coding, the design aim was achieved. The designed system is moderately complex with respect to digital signal processing.  

 

This thesis is supervised by Gernot Kubin, Klaus Witrisal.