Ultra wideband receiver based on pulse position modulation.

摘要

Ultra-wideband (UWB) communications systems have been the subject of extensive research in recent years because of its unique capabilities and potential applications, particularly in short-range multiple access wireless communications. However, many important aspects of UWB-based communication systems have not yet been thoroughly investigated. In this dissertation, we consider some important research issues on designing ultra wideband wireless links for future broadband applications.; The initial study focuses on the performance analysis of UWB communication systems. To evaluate the performance of the time hopping pulse position modulation (TH-PPM) technique, it is important to estimate its ability to work in a multi-user environment. The objective is to demonstrate a method to evaluate the symbol error rate (SER) and capacity performance of TH-PPM in the presence of multi-user interference and AWGN channel. A comparison between the results obtained considering the exact probability density function of the multiple access interference and the ones obtained employing an approximate version of it, based on the Gaussian assumption, is presented.; The next part of this dissertation deals with the practical method of implementing a rake receiver suitable for efficient processing of an UWB signal based on the pulse position modulation (PPM) considered that is denoted as the single bit rake (SBR). The uniform sampling and single bit quantization require in only very simple signal processing. Theoretical analysis and simulations are presented for analyzing the bit error rate (BER) and capacity performance of the proposed system. The capacity of PPM UWB communications over multipath channels based on SBR is proposed. UWB capacity is expressed as a function of frame length and number of rake fingers. The capacity of structured UWB systems is investigated, and performance results are discussed. The effect of adding a block-out period to the frame period on capacity is also considered.; Finally, we propose the narrowband interference mitigation techniques for UWB systems. UWB links are inherently vulnerable to narrowband interference noise from other narrowband communication links. Consequently, it is necessary to implement processing in the UWB receiver that effectively and adaptively suppresses narrowband interference at arbitrary frequencies within the wide operating band. The objective is to investigate various interference suppression techniques in UWB systems to improve capacity and bit error rate performance.