【作者】 徐波；

【导师】 王跃科；

【作者基本信息】 国防科学技术大学 ， 仪器科学与技术， 2011， 博士

【摘要】 CDMA蜂窝移动通信系统因其低功耗和高度的安全性而得到了广泛应用。在CDMA系统体制内,通过移动台与基站交互,可提供用户位置坐标服务,该业务称为合作定位。在系统体制外,若以第三方提供的设备、通过监听通信信号来确定移动台位置,称作非合作定位。由于CDMA系统具备高度安全性(保密性),通过无线信号来监听用户通话、或进行非合作定位,技术难度非常之大。在国家预防和打击犯罪的行动中,这就给安全部门提出了一个技术难题。作为研制CDMA非合作定位设备的基础,其理论依据与技术方法的研究成为必然途径,由此形成本文的研究主题。CDMA非合作定位设备属于特种仪器领域,其关键技术问题属于距离测量问题。忽略移动台在地表平面的起伏高度,其位置坐标的定位可类比为平面上的坐标测定——以此定位设备为侦测站,从空中接收移动台与基站之间的无线信号,从中计算出各侦测站与移动台之间的距离差,并按其几何关系来确定移动台的位置坐标。由此形成本文研究的关键技术问题如下:1、可听区域搜索问题:由于侦测站只能在特定的距离内接收到移动台的发射信号,而移动台的坐标是未知数,如何有效、快速地确定移动台所在的平面区域,成为CDMA非合作定位的一个关键问题。2、反向导频信道跟踪问题:测量移动台与侦测站之间的距离差,需要准确引用CDMA信号中的基准时间和系统中的长码序列片段,才能确定接收信号的有效性、并从中计算出相对时间差。由于CDMA信号体制以42阶长码作为分址和同步的基础,加上移动台上行导频信号中插入非规则的功率控制位序列、且不定期地关断发射信号,因此移动台与侦测站之间的时差测量面临瓶颈性制约难题。3、侦测站最优布局逼近问题:要确定移动台位置,侦测站的布局位置必须按一定的几何构型才能满足必要条件。在未知移动台坐标的前提下,探索侦测站的最优布局,成为非合作定位的关键技术问题。4、定位方程解算问题:移动台的位置坐标归结为定位观测方程组的解。其中时差量、侦测站的位置参量都不可避免地存在误差,容易导致常规非线性方程组解算方法出现病态问题,需要结合非合作定位问题特点,寻找更稳健的优化解算方法。5、定位性能上限问题:非合作定位问题的解决办法肯定是多样性的,但现有研究成果很少、且缺乏完整性,很难评判一个解决方案的优劣。按照研究测量问题的基本规则,需要定量地确定测量误差,推导出定位误差的理论上限。为解决上述关键技术问题,文中通过理论抽象,将复杂的CDMA系统和实际定位情景转化为相对简单的信号与系统模型和测距定位模型(方程),按照时空统一的原则和分析方法,分别给出了前四个问题的解决方案,并给出了非合作定位误差的克拉美罗下限(CRLB)作为第五个问题的答案。从理论回到实践,文中介绍了自行设计的CDMA非合作定位试验样机系统。通过室内假设性条件测试,验证了上述解决方案的可行性;通过长沙、成都、重庆三地的实际使用,检验了系统及解决方案的实用性。实际系统及其理论研究成果已通过科技成果鉴定,得到了本专业领域专家的充分肯定。更多还原

【Abstract】 CDMA cellular mobile communication system is widely applied because of its low power consumption and high degree of safety. In a CDMA system mechanism, the position coordinates of users can be provided through interaction between the mobile station and base station, which is known as the cooperative location. Beyond the system mechanism, the technology that uses equipments provided by the third party to determine mobile station position is called non-cooperative location. As the CDMA system has high security, its level of difficulty in techniques is higher through using the wireless signal to monitor the call of users, or proceeding non-cooperative location. In the national prevention and fighting crime action, it puts forward a technical difficult problem for the security department. As the foundation of developing CDMA non-cooperative location equipments, the study of its theoretical basis and technical methods becomes a necessary approach. Thus it forms research topic of this paper.CDMA non-cooperative location equipment is of the special instruments field and its critical technical issues are of the ranging problem. Ignoring the undulated height of the earth’s surface, the location of position coordinates can be assimilated to the determination of coordinates on the plane. Take this location equipment as detection station, receive radio signals between base station and mobile station from the air, calculate the distance difference between each detection station and mobile station, and then determine the position coordinates of mobile station according to the geometrical relationship. Thus the key technical problems in this paper are as follows:1、Hearable area search problem: As the detection station can only receive the transmit signal of mobile station within a specific distance and the coordinates of mobile station are unknown, it becomes a key problem of CDMA non-cooperative location that how to effectively and quickly determine the plane area where the mobile station is.2、Reverse pilot channel tracking problem: To determine the validity of the received signal and calculate the relative time difference, it needs to quote accurately the reference time in CDMA signals and the long code sequence fragments in the system. CDMA signal system takes the long code of 42 rank as the foundation of division access and synchronization, the uplink pilot signal of mobile station is inserted into irregular power control bit sequence and the transmit signal is shut off aperiodically, therefore time difference measurement between mobile station and detection station faces bottleneck restriction problem.3、Detection station optimal layout approximation problem: To determine mobile station position, the layout position of detection station must be at a stated geometry. In the unknown mobile coordinates premise, exploring the optimal layout of detection station becomes the key technical problem of non-cooperative location.4、Location equations calculating problem: The position coordinates of mobile station come down to the solution of location observation equations. However, the delay difference and the position parameters of detection station exist inevitably errors, which cause the ill-posed problem to the solution of general nonlinear equations. In order to look for the more robust and optimal solution method, it needs to combine the characteristics of non-cooperative location.5、Location performance bound problem: Solution of non-cooperative location problem must be divers, but the few existing research results, lack of integrity, are hard to be judged for good and bad. In accordance with the basic rules of the study measurement issues, it need determine the quantitative measurement errors and derive the theoretical upper limit of location errors.To solve the key technical problems, through the theory abstract in this paper, the complex CDMA system and actual location scene are converted into relatively simple signal and system model and ranging and location model(equation). According to the principle and analysis method of unified space and time, the solutions to solve the front four problems are given and the CRLB of non-cooperative location error is presented as the answer for the fifth problem.From the theory back to practice, this paper introduces the test prototype system of CDMA non-cooperative location which is designed by oneself. In the indoor hypothetical conditions, the test verified the feasibility of the solution afore mentioned. Through actually using in Changsha, Chengdu, and Chongqing, the practicability of the system and solution project gets the certification. The actual system and its theory research production has passed science and technology achievements appraisal and gets the full affirmation.更多还原