【作者】 高翟；

【导师】 朱光喜；

【作者基本信息】 华中科技大学 ， 信息与通信工程， 2012， 博士

【摘要】 移动通信是整个通信领域中发展特别迅速的一部分。在现今通信用户基数大,高移动性的要求下,移动通信在理论及工程实用上均有了长足的发展。而由于移动通信系统相较于有线通信在发射机制、信道传输、接收机制上的特殊性,使得通信过程中的干扰问题显得尤为突出,因此干扰控制的研究成为一个重要方向,在保障系统正常运行、提升用户服务质量(QoS)方面发挥着独特的作用。本文讨论了三种主要的干扰类型——杂散干扰、互调干扰和阻塞干扰,并结合物理层与数据链路层对规避干扰的分数频率复用法进行了创新。全文的研究分为六部分。第一部分研究移动通信系统的干扰理论,包括区别于有线信道的无线信道模型、干扰类别和干扰分析方法。这部分内容是后文分析干扰的理论和方法论基础。学术界对通信干扰的分类法有多种,本章简介了有别于本文分类法中的部分干扰,并在干扰分析方法中逐渐引入本文即将展开的几种干扰类型。第二部分就移动通信中的一种重要干扰——杂散干扰进行研究。在通信发射和接收端的滤波器阻带因子非零的情形下,信号会产生邻频泄漏。如果存在泄漏的频段正好是其它系统的接收频段,则会产生杂散干扰。如今通信频率(特别是800-2500MHz段)资源已相当紧缺,各制式的频段间隔变得很小,这使得杂散干扰发生的概率非常高。本部分在阐述杂散干扰产生机理的基础上,分析不同制式间杂散辐射的程度,仿真计算出实际应用中的隔离度要求,并提出抑制杂散干扰的方案。减小杂散干扰成为提升系统性能的一项重要手段。第三部分研究移动通信中的互调干扰。如果说非理想的滤波导致杂散辐射的话,那么非理想的器件转移引发了互调信号。非理想器件的转移函数除一次项之外,还有二次及以上高次项若干,它们影响器件的线性特性。而使用中的频点越多、频段越密,则发生互调干扰的概率越大。本部分通过详细分析、推导互调干扰的各成分,以此为基础论证互调产物与器件的线性特性间的量化关系,并提出抑制互调干扰的方法。概括地说可以从硬件和软件两方面入手,即增大器件线性输入域和波道规划。第四部分的研究对象是阻塞干扰。在输入功率与通信器件不匹配(通常是输入功率过大)的情形下会发生阻塞干扰,这在高功率发射机普遍使用的今天并不少见。阻塞的表现形式为输出信号幅值与预期相比有较大程度的压缩,从而使信号失真；在压缩程度超过系统容忍的特定限度时,则发生阻塞干扰。本部分仍以器件的线性特性为基础,推导计算出阻塞压缩率与器件转移函数中非线性项的关系,并提出规避阻塞干扰的方法。阻塞与互调干扰成分相关,也受其它造成额外功率输入的噪声或干扰的影响。分别分析了三种干扰类型之后,第五部分通过干扰合路仿真平台将三种干扰整合到一起。能实现整合的原因有二：一是三种干扰的计算都需要实际系统的指标作为入口参数,这样用户只用将所需参数在平台中设置即可进行三种干扰的仿真运算；二是大多数用户关心仿真结论而不在意繁琐的中间计算过程,这样该平台将所有的中间步骤打包封装,仅提供输入和输出界面即可实现简明的人机交互。本部分使用MATLAB软件中的图形用户界面(GUI)程序来编写仿真平台,用户通过窗口数据录入和特殊参数选择完成输入,通过功能按键来控制仿真代码的运行。第六部分从数据链路层的角度,就一种常见的干扰控制方法——分数频率复用法进行研究。在蜂窝无线通信网中,分数频率复用降低了相邻小区(或扇区)间的干扰,提升小区边缘用户的通信质量。传统的分数频率复用有时分和频分两种模式,本部分在此基础上提出一种新的时频分模式,它通过重设帧结构使全复用和部分复用的调节更灵活。在调度的公平性上,时频分模式优于全复用,而更高的调节粒度使它比时分和频分模式更接近理想的自适应复用性能。通过合理设置帧结构的全分复用比,该模式能提升小区内的调度公平性,使边缘用户获得时频资源更有保障。更多还原

【Abstract】 Mobile communication is one of the rapidly developing parts in communication areas. With the large base number and high mobile requirement, mobile communication is progressing sufficiently on its theory and application. As mobile communication system has its particularity on transmitting, channel transferring and receiving compared to wire communication, interference in communication procedures is much more obvious than those of other systems. Therefore, interference control has become a significant research point, which provides special effect on ensuring normal operation and raising quality of service. This paper discusses three types of interference:spurious emission, intermodulation and block distortion. It also innovates fractional frequency reuse from physical layer and data link layer. The content of this paper is divided into six parts.The first part studies basic theories of interference in mobile communication system, including models of wireless channel, sorts of interference and analysis techniques which are distinct from cable channel. This part is the theoretical and technical basis of following researches. There are several ways to classify communication interferences, and this part introduces some types different from that in following chapters. Meanwhile, the core types of interferences in this paper are gradually referred.The second part studies a significant interference, which is called spurious emission interference, in mobile communications. As long as the reject band is not equal to zero in transmitting or receiving terminals, signals will produce adjacent frequency leakage. Then the spurious emission interference takes place if such leakage locates in passband of receiver. At present the available resource of frequency band (especially between 800 to 2500 MHz) is very rare, where adjacent bands of existed systems have little gaps, which leads a high probability of spurious emission interference. This part analyzes its theoretical basis and spurious emission between distinct systems, calculated practical minimum coupling loss by simulation, and raises schemes to restrain such interference. Reducing spurious emission interference is an essential method to upgrade system performance.The third part focuses on intermodulation interference in mobile communications. Just like spurious emission caused by nonideal filtering, nonideal transfer function leads intermodulation. The ideal transfer function is linear (only first order), while the nonideal one contains second or higher orders, which affect the linear character of transferring. If more carriers or frequency bands are activated, intermodulation interference is more likely to occur. This part detailedly analyzes and deduces the elements of intermodulation, and demonstrates the quantitative relationship between intermodulation elements and the linearity of transfer function. After that the methods to mitigate intermodulation interference are put forward. Generally speaking, the methods include both hardware and software, that is, broaden linear input region and channel arrangement.The fourth part investigates block interference. If input power does not match the object device (usually the power exceeds the upper bound), the block interference comes out. It is quite familiar as high-power transmitter is widely used. Block brings an obvious compression on amplitude compared to expectation, which makes distortion in output signal. Block interference takes place when the compression falls out of the permitted region of system. This part is still based on linear character of transferring. The relationship between compression ratio and transfer function is detaily described, after which the techniques to avoid block interference are introduced. Block elements are dependent on several aspects such as intermodulation, additive noise and other types of interference.After analyzing those three types of interference, we integrate them by a simulation platform in the fifth part. There are two reasons on the feasibility of such integration:One reason is their common requirement on practical system data for input parameters; platform users could set these data before calculation for any one sort of interference. The other reason is users’interest on simulation result instead of the complex medium calculating process. The platform separates such process into background and just provides input and output interfaces for a concise man-machine interaction. The simulation platform in programmed by Graphical User Interface (GUI) code in MATLAB environment. Users input data by parameter boxes and multiple choices, and control the programme execution by certain buttons in the input window.An effective scheme for interference control, fractional frequency reuse, is studied in the sixth part from the view of data link layer. In cellular wireless communication netwok, fractional frequency reuse depresses interference between adjacent cells (or sectors), while margin users obtain a higher quality of service. Traditional fractional frequency reuse has two modes:time-divided and frequency-divided. This part raises a new mode, time-frequency mode, based on the previous two modes. This mode has a more flexible adjustment on full reuse and partial reuse by a newly constructed frame structure. Time-frequency mode has a management with better fairness, in which a more subtle granularity leads a performance closer to the ideal adaptive reuse mode. By setting a suitable full-partial reuse ratio in frames, time-frequency mode can improve fairness in cell management, where margin users are able to enjoy more transmission resources.更多还原