【作者】 李争；

【导师】 杨莘元；

【作者基本信息】 哈尔滨工程大学 ， 通信与信息系统， 2006， 博士

【摘要】 近年在短距离(家庭与小型办公室)无线通信领域提出了个人局域网(Personal Area Network，PAN)的概念。PAN的核心思想是用无线电或者红外线代替传统的有限电缆，组建个人化的信息网络。实现PAN的技术主要有：蓝牙(Bluetooth)，IrDA(Infrared Data Association)，Home RF以及超宽带(Ultra WideBand，UWB)等4种。与其它三种技术相比，UWB的高性能和低功耗使得它脱颖而出，成为未来最富有竞争力的技术之一。超宽带通信具有数据传输速率高、功率谱密度低、定位精度高以及抗多径能力强等优点，因此它很可能是未来短距离无线移动通信高速传输多媒体信息，高速接入计算机网络的关键技术，现已成为国内外学者在无线通信技术方面的一个研究热点。本文研究了UWB的关键技术，涉及脉冲波形设计、多用户检测技术、编译码算法研究以及室内多个UWB设备对移动通信终端合成干扰研究。为了实现与现有窄带无线通信系统共存，FCC对超宽带系统的功率谱作了严格的限定，这就引出UWB系统设计与实现的难题。在UWB无线电中，人们目前广泛采用的是高斯单脉冲，它具有超宽带无线电脉冲的特征，且具有实现便利性。但高斯单脉冲并不满足FFC频谱规定。于是一些学者提出了一些UWB脉冲波形优化设计，但是现有UWB脉冲波形的设计方法，设计过程复杂，要求复杂的优化算法，并且要求的采样率极高。本文从波形的频谱利用率角度考虑，提出了基于高斯脉冲各阶导函数优化组合的超宽带脉冲设计，通过优化基于高斯脉冲的不同导函数组合的脉冲设计算法来得到最优波形，使功率谱密度接近标准，并且提高了频谱利用率。在多用户通信系统中，由于各种各样的原因，在接收端期望用户的接收机除了接收到自己的期望信号外，还会不可避免的接收到非期望信号，即受到多用户干扰(MUI)的影响。目前对UWB的多址方式研究主要集中在两个方面。通过给不同的用户分配不同的跳时(TH)序列形成了跳时多址(THMA)；通过给每一个不同的用户分配不同的直扩序列形成了直扩UWB(DS-UWB)。针对跳时多址方式，本文利用了跳时序列的特殊性质提出了一种低复杂度的解相关接收机，减少了计算复杂度而又降低了多址干扰的影响，同时对其进行了改经，性能又进一步得到了提高。针对直扩多址方式，本文提出了一种带预处理的多用户检测器，通过预处理动态的设定门限从而直接判决用户的数据比特信息，计算结果表明经过预处理得到的数据与最佳多用户检测器得到的数据相同，而且复杂度从原理的指数复杂度变为多项式时间复杂度，并且通过预处理得到的用户信息码的数量是很大的。由于通过预处理得到的数据已经是最优的，这样可以去除这些数据从而去除对原多用户检测问题的影响，相对于原问题这个较小规模的多用户检测问题的多址干扰减小了，之后可以采用一些常用的诸如解相关或者最小均方误差检测器进行求解，其误码性能无疑有所提高。为了提高整个系统的抗干扰能力和纠错能力，我们可以将信道编码技术与UWB结合起来。由于UWB是一个高速率的通信系统，因此编码方案必须速率要低而且编码后的码字要尽量短。本文提出了半定初态卷积编码的概念，并且在此基础上给出了其编译码的算法。该编译码算法较好的解决了编码性能与编码后码字长度的矛盾，通过仿真可以看到，在保证编码后码字长度尽量短的条件下，其性能逼近最佳性能，是一种十分实用的编译码算法。针对多个UWB设备对移动终端的合成干扰问题，从三维空间出发并考虑了UWB设备活动性统计角度，以及考虑室内条件下接收机的共道干扰的影响，提出了一种改进的算法，得出了一系列相关的结论。综上所述，本文研究了UWB的关键技术，提出了一些相应的解决方法，仿真实验验证了本文所提出的模型及算法能够获得很好的效果。更多还原

【Abstract】 Recently, it presents PAN in area of short-range wireless communication. Instead of using cables, PAN uses radio or infrared to build up information network. Technologies to realize PAN have buletooth, IrDA, Home RF and UWB. Compared with others, UWB’s high performance and low power make it competitive. UWB has such advantages: high data rate, low spectrum density, high precision location identification and inherently exceptional multi-path immunity, so it can become the crucial technology of future short-range wireless communication and accessing computer network, it has become the research focus in the wireless communication field.This paper research about UWB’s key technologies, including pulse design, multi-user detection, code and decode, interference of UWB devices to mobile communication terminators.In order to coexist with existing communication systems, FCC regulates strictly on UWB’s spectrum density. In UWB radio, Gaussian pulse use widely, it characterizes UWB wireless pulse and it can realize easily, but in cannot satisfy with FCC’s regulation. Some researchers present some improved methods, but these are complicated. This paper present pulse design based on different Gauss and derivatives, it makes spectrum approximate standard and increase spectrum efficiency.In multi-access communication system, due to various reasons, MUI can affect the system. There are two main multi-access, one is THMA and the other is DS-UWB. For THMA, we use the specific properties of TH sequences and present a reduced complexity multi-user detection, then we improved it and the performance gets better. For DS-UWB, we present a multi-user detection with pretreater, the pretreater mentioned in this paper can calculate most user information sequences by low computational complexity and assure that the results obtained from pretreater are the same as that of optimum multiuser detection. Since the user information sequences obtained from pretreater have been global optimization, we can reduce them from original multi-user detector and then a relative small scale multi-user detector can be obtained. Compared with the original one, the multi-access interference of small scale multi-user detector is reduced. As a result, we can solve this small scale multi-user detection by some common multi-user detector.In order to improve system’s performance, we can combine UWB with encode. Because UWB is a high data rate system, the encode project should be low rate and the codeword after encode should be short. This paper present semi-determinative initial state convolutional coding and decoding algorithm. This algorithm perfectly deals with the conflict between the performance of coding and the codeword after coding length after coding. Being sure of the codeword length, its performance approximated its optimum performance, making it a pragmatic coding and decoding algorithm.For the impact of cumulative interference from multiple UWB devices to mobile communication devices, we consider a three-dimensional geometry for the spatial distribution of the UWB devices. The outcome of this study is a statistical model, i.e. a probability density function (PDF). With this model, the maximum interference from multiple UWB devices, the maximum acceptable UWB-device density, the minimum distance between UWB devices and receiver are derived in different link budget degradation.In conclusion, we study key technologies of UWB, and new models and algorithms had been proposed, simulations and experiments had tested that the models and algorithms can get good results.更多还原