科技译文移动通信系统定位技术

摘要： 本论文主要研究CDMA蜂窝移动通信系统用户定位技术

的理论与实践问题。第一，根据空时无线通信矢量信道模型，本文给出了单用户和多用户条件下接收信号的模型，并推导了多径、多天线和分数阶采样条件下，时延、幅度、到达角、平均功率等参数的克拉美罗界并分析了其渐近性能。对于信道参数估计性能界的理论推导，为定位性能的分析奠定了基础。 第二，在参数估计的基础上，推导了无偏估计状态下单用户和多用户位置估计的克拉美罗界，并给出了单参数定位体制(TOA、TDOA、AOA、SOA)及混合参数定位体制(TOA／AOA、TDOA／AOA和SOA／AOA)下，定位估计性能界的解析表达式。 第三，对视距环境下多种基于多传感器的定位算法进行了详细分析，并提出了两种应用于蜂窝系统的用户定位算法：基于最小二乘估计的TDOA速迭代定位算法和基于线性校正最小二乘的TDOA／AOA定位算法。采用蒙特卡罗方法仿真了TDOA和AOA的测量精度、误差分布特性及参与定位的基站数量等参数对算法定位性能的影响。 第四，非视距传播使参数估计的结果不再是无偏估计，所以本文根据蜂窝系统散射模型推导了宏蜂窝和微蜂窝环境中非视距误差的分布，采用渐近均方根误差作为衡量指标。第五，论文最后简单介绍了几种新型的定位方法及辅助定位方法。 关键字：定位 到达角 非视距 Cell-ID GPS

Summary：There has been a long history with wireless position location techniques. The fast development in techniques and

the rapid growth in demand for cellular communications services have been encouraging research into the deployment of wireless position location techniques in civilian applications. In June 1996, the Federal Communications Commission (FCC) of United States created rules that require cellular service providers to provide the position of cellular 911 callers to Public Safety Answering Points. The accuracy requirement of the E-911 mandate was initially set to within 125 metres for 67% of users and within 300 metres for 95% of users. In the final phase of E-911 mandate, these numbers are subsequently reduced to within 50 metres and 150 metres for handset-based solutions, 100 metres and 300 metres for network-based solutions, respectively. In many applications with special purposes, such as emergency, national security and military deployment, subscriber position location is very necessary.This dissertation addresses problems of locating cellular subscribers and focuses on the theory and applications of position location techniques in cellular networks, especially in the widely deployed cdma2000 1x and IS-95 CDMA systems. These key issues include signal hearability on reverse channels, bounds on parameter and location estimations, location algorithms with LOS or NLOS measurements and the implementation of a third

party(passive) subscriber position location system based on TDOA measurements.First of all, signal hearability is thoroughly analyzed with cdma2000 1x signal as an example. \accquisition probability\performance criteria for the capability of location system coverage. The analysis shows that hearability is poor for location purposes. To improve signal hearability, a scheme is proposed that signal interception and subscriber position location are implemented on reverse access because larger time-bandwidth production can be achieved. Simulation results show that there is great performance improvement in signal interception probability.A key aspect of subscriber location is the estimation of the channel and channel parameters whose estimation accuracy determines the reliability of location estimation. The channel parameters of interest include the strength of arrival(SOA), angle of arrival (AOA), time of arrival(TOA) and time difference of arrival(TDOA). After presenting the temporal and specular propagation model, the CRLB on channel parameter estimation is derived. Then the CRLBs for the estimation of subscriber location under two scenerios ---- single user and multiple users ---are derived and

thoroughly analyzed. Analysis results show that the CRLB under circumstances where many cellular phones work simultaneously is independent on multiple access

interference.The subscriber position is normally obtained by solving nonlinear equations. However, it represents a high computational burden and may suffer from a convergence problem.

Key words: positioning doas non line-of-sight Cell - ID GPS

引言：近年来，随着蜂窝移动通信技术的迅速发展，蜂窝无线定位技术越来越受到

人们的重视。这主要归因于政府的强制性要求和市场本身的驱动。 FCC于1996年10月颁布了无线E9ll呼叫应急服务功能，其核心是要求所有移动通信网络必须分阶段的提供紧急呼叫用户的经纬度位置信息。针对E911定位需求的具体实施，各国主要大公司均就 GSM、IS-95 CDMA以及第三代移动通信系统开始制定各自的定位实施方案。特别是 3GPP和3GPP2上对定位的要求更加具体化，这也是对蜂窝无线定位市场潜力的肯定。另一方面，移动通信用户对移动定位业务的需求日益迫切。蜂窝网络无线定位技术能够在移动台处于空闲状态或通话状态的情况卜获取其地理位置等信息，利用移动台的定位信息，运营商可以为用户提供各种增值业务，如位置环境信息查询、紧急救援、智能交通、广告发布等等，同时还可以作为移动通信网络运行、维护和管理的辅助数据。到目前为止，基于蜂窝网络的无线定位技术的研究已经取得了很大的进展。可以预见在未来几年内，基于蜂窝网络定位技术的移动业务将得以迅猛的发展。

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