【作者】 房兆路；

【导师】 朱守正；

【作者基本信息】 华东师范大学 ， 无线电物理， 2005， 硕士

【摘要】 PHS是个人手持电话系统(Personal Handyphone System)的简称,由日本无线系统研发中心(RCR)在上世纪90年代初开始研发。PHS与目前广泛使用的GSM、窄带CDMA等同属于第二代移动通信系统。在我国PHS俗称小灵通,所采用的无线接入系统是在日本PHS系统的基础上经过改进后推出的。上海电信的小灵通网络始建于2002年,目前已经具有一定的规模。但是,由于上海是一个国际化的大都市,建筑物的地理分布复杂,高层建筑多,电波的传播环境比较复杂,加上一些人为的因素,目前的网络存在诸如信号覆盖不足、掉话、频繁切换等问题,严重影响了网络的质量。因此迫切需要对现有网络进行优化,提高网络的质量,减少用户的投诉率,提高用户的满意度。小灵通系统属于移动通信系统,本文首先分析了PHS无线网络的基本原理,了解其空中接口的结构、机制和流程。本文重点研究了PHS系统无线电波的传播特性,从对无线通信损耗衰落和多径特性理论分析研究开始,结合小灵通系统特点,建立了适合小灵通无线网络的传播预测模型,给出了一种基于三维射线跟踪八叉树算法的PHS系统微小区电波传播预测的算法,为无线网络优化工作提供了理论依据,这也是本论文的主要创新之处。PHS无线网络具有发射功率低、使用频段高、传播损耗大等特点,极易受周围环境变化的影响,因此建立无线电波传播损耗模型和进行覆盖预测对进行网络优化、改善网络质量具有重要意义。无线电波的损耗模型和传播预测是进行PHS无线网络规划和优化工作的理论基础,并为后者提供指导意见。另外,对于无线网络中存在的主要问题如网络覆盖、基站同步、基站干扰、基站切换和PA区规划等,本文提出了优化解决的方法,并在网络优化的实践中得到了验证。无线网络优化是对投入运行的小灵通无线网络进行参数采集和数据分析,从中找出影响无线网络质量的因素,通过技术手段或参数调整使得无线网络达到最佳运行状态。无线网络优化是一项长期复杂的工作,因此要清楚网络优化需注意的问题以及无线网络优化的流程,熟悉无线网络性能分析和问题定位。结合本文提出的电波传播预测模型和算法以及无线网络优化的流程和方法,本文给出了几个上海电信PHS无线网络优化的典型案例。更多还原

【Abstract】 PHS (Personal Handyphone System) is a personal wireless communication system belonging to the second generation mobile communication. It was developed by the RCR (Research and Development Center for Radio Systems) of Japan in the early 1990s and its criterion standard is RCR-STD28.The construction of the PHS network in Shanghai began in 2002. It has a rapid development and the subscribers have been over 1,000,000. At present, the system has some problems such as short of signal overcast, breaking off of the communication and frequent handover, etc. All these problems have affected the service quality. So it’s necessitous to do some optimization for the wireless network.For the good of optimization of the network, first we need to analyze its principle and know something about the structure, mechanism and flow of the space access.The prediction of the propagation of electromagnetic wave is most important in urban areas where subscriber density is high, and the buildings have a profound influence on the propagation. In this dissertation, we found a propagation model to analyze the path loss and an arithmetic based on ray tracing octree technique for the propagation prediction. This gives the theoretical foundation for the optimization of the PHS network. The most transmitting power of the base station is only 500 mW, and the frequency band used in PHS is 1900 MHz, so there is a great loss of energy along the transmission path.The optimization of the PHS wireless network is a long and tough work. Firstly we gather the operating data from the software of the network management or using the measurement tools; secondly we analyze the data and find the problems in the wireless network; thirdly we find the methods to solve these problems. Some methods for the typical problems is given, this will accelerate the optimization.There is a short history of the optimization in Shanghai, and we must learn and accumulate experience during the practice. At the end of this dissertation, we give several typical cases of the wireless network optimization with the models and methods given in this dissertation.更多还原