Study on Reliable Low-power Wireless Communication Systems Using Multiband Pulsed UWB Technlogy

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The goal of this project is developing reliable low-power wireless communications by using multiband pulsed ultra wide band (UWB) technology. In this project, the following topics are investigated.First, the performance of direct sequence ultra wide band (DS/UWB) systems is evaluated under the multipath fading environment from the viewpoint of ensuring a certain level of error rate performance by using cumulative distribution function (CDF) of bit error rate.Second, performance of cooperative communications for DS/UWB in multipath channel is investigated. According to the computer simulation results, it is found that use of cooperative communications is effective to improve the performance in non line-of-sight multipath channel comparing with the use of conventional diversity reception in DS/UWB.Third topic is the acquisition performance DS/UWB communication systems, especially in packet communications. In wireless packet transmission, the acquisition must be completed in the preamble duration in the packet. In this project, RAKE combining and verification mode is employed in DS/UWB packet transmission to combat multipath fading. According to the simulation results under the IEEE802.15.4a multipath fading environment, significant improvement of acquisition probability is achieved by using RAKE combining. Also, mean acquisition time becomes shorter when the verification mode is equipped with the DS/UWB acquisition system. Also, using peak detector and interval estimation is proposed to achieve faster and more accurate acquisition in multipath fading environment. Computer simulation results show that the peak detection and interval estimation is effective to capture the accurate peak of the matched filter output in the DS/UWB acquisition. In addition, thereduction of the acquisition time is achievable by optimal design of the capturing interval for the peak detection.