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

该项目的目标是利用多波段脉冲超宽带（UWB）技术开发可靠的低功耗无线通信。在这个项目中，研究了以下主题。首先，从保证一定误码率性能的角度出发，利用误码率累积分布函数（CDF）对直接序列超宽带（DS/UWB）系统在多径衰落环境下的性能进行了评价。其次，研究了多径信道下DS/UWB协同通信的性能。计算机仿真结果表明，在非视距多径信道中，与传统的DS/UWB分集接收方式相比，采用协同通信方式可以有效地提高系统的性能。第三个主题是DS/UWB通信系统的采集性能，特别是分组通信。在无线分组传输中，采集必须在分组的前导时间内完成。本课题在DS/UWB分组传输中采用RAKE组合验证模式来对抗多径衰落。在ieee802.15.a多径衰落环境下的仿真结果表明，采用RAKE组合可以显著提高捕获概率。此外，当验证模式配备DS/UWB采集系统时，平均采集时间缩短。在多径衰落环境下，利用峰值检测器和间隔估计实现更快、更准确的信号采集。计算机仿真结果表明，在DS/UWB采集中，峰值检测和区间估计能够有效捕获匹配滤波器输出的准确峰值。此外，通过对峰值检测的捕获间隔进行优化设计，可以减少采集时间。

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.