铁路LTE系统服务质量测试与网络优化
<img src="https://mmbiz.qpic.cn/mmbiz/yqVAqoZvDibEaicDyIvX7dLE9icYnwb2tlOWcD2BP99V6iaCfkk81RZlQARicbNr7amQ7a0Lc3tFgpNJNEVaY188ZVQ/640?wx_fmt=png&tp=webp&wxfrom=5&wx_lazy=1&wx_co=1" style="width: 50%; margin-bottom: 20px;"><span style="color: black;">点击上方“<span style="color: black;">蓝字</span>”关注<span style="color: black;">咱们</span>吧~</span><span style="color: black;">铁路LTE系统服务质量测试与网络优化</span><p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">赵麟杰</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">（中国铁路通信信号上海工程局集团有限<span style="color: black;">机构</span>，上海 200436<span style="color: black;">）</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;"><span style="color: black;"><strong style="color: blue;">摘要：</strong></span><span style="color: black;">从铁路专用LTE网络的基本<span style="color: black;">形成</span>出发，<span style="color: black;">详细</span>介绍服务质量测试指标和网络优化的<span style="color: black;">重点</span><span style="color: black;">办法</span>。<span style="color: black;">经过</span>对无线场强覆盖、车地通道性能以及切换性能等关键参数的测试，<span style="color: black;">能够</span>客观<span style="color: black;">评定</span>列车高速移动状态下的网络性能指标，<span style="color: black;">亦</span>为无线网络优化<span style="color: black;">供给</span>可信数据依据，使铁路专用LTE无线宽带通信系统的工程质量得到有效<span style="color: black;">保证</span>。</span></span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;"><span style="color: black;"><strong style="color: blue;">关键词：</strong></span>铁路；LTE；服务质量；网络优化；测试</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;"><strong style="color: blue;">中图<span style="color: black;">归类</span>号：</strong></span><span style="color: black;">U285.5+5</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;"><strong style="color: blue;">文献标识码：</strong></span><span style="color: black;">A</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;"><strong style="color: blue;"><span style="color: black;">文案</span>编号：</strong></span><span style="color: black;">1673-4440(2018)03-0040-06</span></p>DOI10.3969/j.issn.1673-4440.2018.03.008<span style="color: black;">Service Quality Test and Network Optimization of Railway LTE System</span>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">Zhao Linjie</p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;">(China Railway Signal & communication Shanghai Engineering Bureau Group Ltd., Shanghai 200436<span style="color: black;">）</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;"><strong style="color: blue;">Abstract:</strong></span> <span style="color: black;">Based on the basic composition of LTE network for railways, the paper introduces the service quality test indexes and the main measures of network optimization. Trough the test of the key parameters such as wireless coverage, train-ground channel performance and switching performance, the network performance can be objectively evaluated under the state of train running with high speed, also can provide reliable data basis for the optimization of wireless network to ensure the engineering quality of railway LTE wireless broadband communication systems.</span></p><span style="color: black;"><strong style="color: blue;">Keywords:</strong><span style="color: black;">railway; LTE; service quality; network optimization; test</span></span>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">近年来，第四代移动通信（LTE）技术<span style="color: black;">已然</span>在民用通信<span style="color: black;">行业</span>内<span style="color: black;">得到</span>大规模发展，<span style="color: black;">亦</span>给铁路等轨道交通专用通信系统的宽带化发展带来了契机。铁路专用化的LTE无线通信系统，与<span style="color: black;">通常</span>电信运营商的常规网络在特殊地理区域的无线覆盖模式、网络服务质量指标等多个方面<span style="color: black;">拥有</span><span style="color: black;">显著</span>的差别，尤其是铁路专用化的高<span style="color: black;">靠谱</span>性业务，如列车调度通信、无线重联、可控列尾、高清视频传送等，更要<span style="color: black;">保准</span>网络高速畅通、稳定<span style="color: black;">靠谱</span>，这就对LTE网络服务质量提出更高的<span style="color: black;">需求</span>。<span style="color: black;">因此呢</span>，铁路LTE网络服务质量测试和网络优化工作<span style="color: black;">显出</span>尤为重要。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><strong style="color: blue;"><span style="color: black;">1 铁路LTE系统简介</span></strong></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">典型铁路专用LTE宽带通信系统<span style="color: black;">通常</span>采用双网架构，即以2个独立的A、B双层网络<span style="color: black;">同期</span>工作，LTE终端会优先<span style="color: black;">选取</span>其中1个网络，<span style="color: black;">反常</span>时重新<span style="color: black;">选取</span>另一张网络。如图1所示。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><img src="https://mmbiz.qpic.cn/mmbiz_png/Pkyzz7OpYqvHFRbFQ6GesBxYDLumhesQxONGJrRDUI3JvmTYeIRfuYF0bXknvsOqwJuia9DCaNMeQG6UF5k3Txg/640?wx_fmt=png&tp=webp&wxfrom=5&wx_lazy=1&wx_co=1" style="width: 50%; margin-bottom: 20px;"></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">铁路LTE系统需要<span style="color: black;">保证</span>列车在行驶区间的无线场强全覆盖，区域内无其他干扰信号，<span style="color: black;">保准</span>列车高速行进过程中无线通信不中断，跨区瞬间切换成功，从而<span style="color: black;">保证</span>承载的各项铁路专用业务能够正常工作。<span style="color: black;">因此呢</span>在网络覆盖方面，采用A/B双层网络负荷分担方式工作，两网<span style="color: black;">同期</span>承载业务数据，如图2所示。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><img src="https://mmbiz.qpic.cn/mmbiz_png/Pkyzz7OpYqvHFRbFQ6GesBxYDLumhesQ7oKJfiaicOfkIDRMZLFA5rsM5iceCF8pdAGL2uHdtJHR1PV1syia70KwuQ/640?wx_fmt=png&tp=webp&wxfrom=5&wx_lazy=1&wx_co=1" style="width: 50%; margin-bottom: 20px;"></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">铁路专用的LTE网络，<span style="color: black;">通常</span>沿着铁路沿线进行无线覆盖，<span style="color: black;">因此呢</span>形<span style="color: black;">成为了</span>典型的“带状”覆盖，而与民用通信的“平面”覆盖有着<span style="color: black;">很强</span>差别，朔黄铁路LTE<span style="color: black;">实验</span>段“带状覆盖”示例，如图3所示。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><img src="https://mmbiz.qpic.cn/mmbiz_png/Pkyzz7OpYqvHFRbFQ6GesBxYDLumhesQ3snGxe9IiczVRxeo3mCOTpVC7nUuys3uTyNvzPZK76JRP5wo1hoYLibQ/640?wx_fmt=png&tp=webp&wxfrom=5&wx_lazy=1&wx_co=1" style="width: 50%; margin-bottom: 20px;"></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><strong style="color: blue;"><span style="color: black;">2 网络服务质量测试技术</span></strong></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">LTE系统的设计<span style="color: black;">目的</span>和工程质量需要<span style="color: black;">实质</span>测试结果来验证，网络服务质量指标就<span style="color: black;">表现</span>了工程质量<span style="color: black;">状况</span>。LTE网络的服务质量<span style="color: black;">评定</span>技术较传统2G/3G无线测试技术又有新的发展。<span style="color: black;">首要</span>，铁路带状环境的无线场强覆盖需满足最小参考功率RSRP；其次，针对铁路专用业务承载能力制定服务质量标准，<span style="color: black;">重点</span><span style="color: black;">包含</span>吞吐量、端到端传输时延、切换成功率、切换中断时间、呼叫<span style="color: black;">创立</span>时间等重要指标，较<span style="color: black;">通常</span>民用无线通信质量<span style="color: black;">需求</span>高。应用LTE宽带移动通信测试工具和业务仿真模拟工具测试服务质量，参照列车行进速度模拟业务通信，进行网络客观<span style="color: black;">评定</span>，获取关键服务质量数据，为后续网络优化<span style="color: black;">供给</span>依据。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">2.1 LTE系统无线场强覆盖测试</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">无线场强覆盖指标用车载终端全向接收天线接收到的最小下行参考信号功率RSRP来描述，设备的最小RSRP值<span style="color: black;">通常</span>为-105 dBm,<span style="color: black;">小于</span>该值将<span style="color: black;">没法</span>正常工作。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">LTE场强覆盖测试框如图4所示，为模拟现网<span style="color: black;">状况</span>，测试时需对上行进行加载，下行进行加扰。上行加载采用移动端服务器<span style="color: black;">经过</span>LTE无线终端与固定端服务器进行数据交互，模拟上行用户工作；下行加扰采用OCNG（OFDMA Channel Noise Generator）方式进行模拟比例加扰，加扰比例分别为0%、50%、70%。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><img src="https://mmbiz.qpic.cn/mmbiz_png/Pkyzz7OpYqvHFRbFQ6GesBxYDLumhesQP7ArxcxPaZEg8OOkWc0G46esEiaFfYb8KnHia4ZVgkeQbgNztntKwpDQ/640?wx_fmt=png&tp=webp&wxfrom=5&wx_lazy=1&wx_co=1" style="width: 50%; margin-bottom: 20px;"></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">测试过程中，<span style="color: black;">经过</span>LTE路测系统连接扫频仪<span style="color: black;">或</span>测试终端分别对<span style="color: black;">各样</span>加扰<span style="color: black;">状况</span>下的LTE系统的RSRP进行测试记录，并绘制RSRP曲线。如图5所示，为某一区段RSRP的测试结果曲线，形状似正弦波，其信号接收强度基本<span style="color: black;">处在</span>-65 dBm和-100 dBm区间，基本能满足通信能力<span style="color: black;">需要</span>。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><img src="https://mmbiz.qpic.cn/mmbiz_png/Pkyzz7OpYqvHFRbFQ6GesBxYDLumhesQskulZwRpGHLV7bp4ySWruqhhTZmWVJiakazZYE0nFHn62TV1eiaeGaiag/640?wx_fmt=png&tp=webp&wxfrom=5&wx_lazy=1&wx_co=1" style="width: 50%; margin-bottom: 20px;"></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">2.2 LTE系统车地无线传输性能测试</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">车地无线传输性能是<span style="color: black;">评估</span>LTE网络运行<span style="color: black;">状况</span>的重要指标，反映了LTE网络所能实现的端到端性能，<span style="color: black;">重点</span><span style="color: black;">包含</span>平均吞吐量、时延和丢包率等指标。LTE系统车地无线传输性能测试框如图6所示，测试时网络<span style="color: black;">处在</span>空载状态。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><img src="https://mmbiz.qpic.cn/mmbiz_png/Pkyzz7OpYqvHFRbFQ6GesBxYDLumhesQr85UjZeD8QH0ibiakMT69rXf93oPfqTiaqKZMrxPACyrBicaeJeITib0buA/640?wx_fmt=png&tp=webp&wxfrom=5&wx_lazy=1&wx_co=1" style="width: 50%; margin-bottom: 20px;"></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">1）平均吞吐量测试：LTE测试终端1进行上行吞吐量测试，LTE测试终端2进行下行吞吐量测试，固定端服务器进行<span style="color: black;">协同</span>测试。测试完成后绘制上行吞吐量曲线和下行吞吐量曲线，并分别计算上、下行平均吞吐量。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">2）时延测试分为用户面和<span style="color: black;">掌控</span>面时延测试：</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">用户面时延<span style="color: black;">重点</span>指LTE移动终端至固定端服务器的时延，采用LTE路测系统<span style="color: black;">经过</span>LTE测试终端1<span style="color: black;">经过</span>PING固定端服务器，进行用户面时延测试，测试结束后，记录最大时延、平均时延、最小时延和丢包率。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;"><span style="color: black;">掌控</span>面时延<span style="color: black;">指的是</span>移动终端从空闲(IDLE)状态进入激活(Active)状态的时延，采用LTE路测系统<span style="color: black;">掌控</span>LTE测试终端2<span style="color: black;">处在</span>空闲状态；<span style="color: black;">而后</span>从空闲状态接入系统，进入激活状态并进行重复测试，测试完成后，统计最大时延、平均时延和最小时延。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">3）丢包率测试：在进行用户面时延测试的<span style="color: black;">同期</span>进行丢包率测试。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">以某重载铁路LTE系统测试结果为例，如表1所示，展现了较好的宽带通信能力和较短的传输时延，丢包现象不显现，均满足项目预期确定的双向吞吐量≥15 Mbit/s、车→地吞吐量≥6 Mbit/s、地→车吞吐量≥8 Mbit/s的<span style="color: black;">目的</span>。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><img src="https://mmbiz.qpic.cn/mmbiz_png/Pkyzz7OpYqvHFRbFQ6GesBxYDLumhesQuYLPC9jPrwuV2CvM5IfFBITLGFqicWNM7o5mn1lOicWqZ9tcxetvOgyg/640?wx_fmt=png&tp=webp&wxfrom=5&wx_lazy=1&wx_co=1" style="width: 50%; margin-bottom: 20px;"></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">2.3 切换性能测试</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">切换性能测试反映LTE网络所能实现的移动终端从一个小区切换到<span style="color: black;">另一</span>一个小区的性能。切换性能测试<span style="color: black;">重点</span><span style="color: black;">包含</span>切换成功率测试和切换时延测试。切换成功率<span style="color: black;">指的是</span>切换成功次数/切换尝试次数，切换尝试指在预期的切换区（如从小区A覆盖区向小区B覆盖区移动）预期<span style="color: black;">出现</span>的切换；切换成功以信令交互完<span style="color: black;">作为</span>指标（LTE测试终端向源小区发送<span style="color: black;">测绘</span>报告信令后，LTE测试终端收到切换指令“RRC连接重配置”信令，随后测试终端向<span style="color: black;">目的</span>小区发送“RRC连接重配置完成”信令）。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">切换时延<span style="color: black;">经过</span>信令来统计，从<span style="color: black;">测绘</span>报告后的<span style="color: black;">第1</span>个“RRC连接重配置”信令（<span style="color: black;">包括</span>源小区向测试终端发送的切换命令内容）到“RRC连接重配置完成”信令（<span style="color: black;">包括</span>测试终端向<span style="color: black;">目的</span>小区发送的切换完成内容）之间的时间差。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">切换性能测试可与平均吞吐量测试一并进行。以某重载铁路LTE系统切换性能测试结果为例，如表2所示，展现了较好的切换成功率，满足时延<200 ms成功率≥99.5%的预期指标。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><img src="https://mmbiz.qpic.cn/mmbiz_png/Pkyzz7OpYqvHFRbFQ6GesBxYDLumhesQ91Llh1WtrynRUuOZfY4Arys2icNlzRsNRw2LfI5u0KxOibBaE6O8MsYQ/640?wx_fmt=png&tp=webp&wxfrom=5&wx_lazy=1&wx_co=1" style="width: 50%; margin-bottom: 20px;"></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">2.4 其他服务质量测试内容</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">除此之外，服务质量指标<span style="color: black;">包含</span>网络注册时延、连接<span style="color: black;">创立</span>时延、连接<span style="color: black;">创立</span>失败率等<span style="color: black;">有些</span>静态测试指标。铁路调度通信所<span style="color: black;">触及</span>的内容<span style="color: black;">包含</span>单呼、组呼、广播、优先级呼叫等，其中端到端呼叫<span style="color: black;">创立</span>时间和呼叫成功率等以某重载铁路LTE系统呼叫测试测试结果为例，如表3所示，均满足项目预期确定的呼叫<span style="color: black;">创立</span>时间<3 s、呼叫成功率>99%的<span style="color: black;">目的</span>。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><img src="https://mmbiz.qpic.cn/mmbiz_png/Pkyzz7OpYqvHFRbFQ6GesBxYDLumhesQzel0A53zB7erXia3XVeveBFAKwtiaghmLGyGxuZPjnqFPb1ISmWHicSgQ/640?wx_fmt=png&tp=webp&wxfrom=5&wx_lazy=1&wx_co=1" style="width: 50%; margin-bottom: 20px;"></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><strong style="color: blue;"><span style="color: black;">3 LTE无线网络优化</span></strong></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">网络优化是系统正常开通和后续<span style="color: black;">保证</span>的一项重要工作，<span style="color: black;">实质</span>业务系统运行后，原先未能<span style="color: black;">即时</span><span style="color: black;">发掘</span>或预料不到的问题将会显现出来，尤其是铁路沿线的地形<span style="color: black;">繁杂</span>，气象环境变化、以及<span style="color: black;">外边</span>信号干扰等均会影响网络质量，需要对网络进行优化调试，<span style="color: black;">经过</span>对基站天线<span style="color: black;">方向</span><span style="color: black;">调节</span>优化覆盖、系统参数调优等一系列<span style="color: black;">办法</span>对<span style="color: black;">明显</span>问题进行重点优化，以<span style="color: black;">处理</span><span style="color: black;">最后</span><span style="color: black;">实质</span>业务应用<span style="color: black;">状况</span>下的网络质量问题，<span style="color: black;">保准</span>系统整体的可用性和<span style="color: black;">实质</span>业务的运行效果。LTE无线网络调试流程如图7所示。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><img src="https://mmbiz.qpic.cn/mmbiz_png/Pkyzz7OpYqvHFRbFQ6GesBxYDLumhesQXhPIEVYicicrYnIjiawKibkMWdibiaIDBRhr6UzU7MmWhr1mpsg8icXZvXJZQ/640?wx_fmt=png&tp=webp&wxfrom=5&wx_lazy=1&wx_co=1" style="width: 50%; margin-bottom: 20px;"></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">3.1 问题定位</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">1）工作准备<span style="color: black;">周期</span><span style="color: black;">重点</span>完成测试工具准备、优化计划制定、网络信息收集等工作，其中网络信息收</span><span style="color: black;">集<span style="color: black;">重点</span><span style="color: black;">包含</span>工程规划参数收集、基站配置信息收集等，可为后续工作<span style="color: black;">供给</span>数据输入；</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">2）单站问题定位<span style="color: black;">重点</span>完成单基站故障等问题的处理，如基站告警、单基站<span style="color: black;">没法</span>接入用户等；</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">3）话统分析<span style="color: black;">重点</span>对基站收集到的<span style="color: black;">各样</span>网络<span style="color: black;">关联</span>的数据信息进行分析，并结合现场测试对<span style="color: black;">发掘</span>的网络问题进行定位；</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">4）网络服务质量测试<span style="color: black;">重点</span>用来<span style="color: black;">发掘</span>覆盖、接入、切换等问题，并结合话统分析数据对<span style="color: black;">显现</span>的弱覆盖、过覆盖、接入失败、切换不<span style="color: black;">恰当</span>等网络问题进行定位和处理。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">3.2 优化分析</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">收集完成<span style="color: black;">各样</span>测试项目所采集的数据后，对数据进行相应的回放及后处理，<span style="color: black;">重点</span>对如下几个方面进行分析：</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">1）覆盖：如RSRP、SINR、RSRQ、PCI分布、各扇区PCI覆盖图等，这是整体衡量空口质量的重要方面，某重载铁路LTE通信系统<span style="color: black;">实验</span>段工程加扰覆盖分析如图8所示。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><img src="https://mmbiz.qpic.cn/mmbiz_png/Pkyzz7OpYqvHFRbFQ6GesBxYDLumhesQYzPHN3odHeIvrzMsWLJ7WEJrcJM8ibMDL94cwDbxibfLkV7HfHH7D6eA/640?wx_fmt=png&tp=webp&wxfrom=5&wx_lazy=1&wx_co=1" style="width: 50%; margin-bottom: 20px;"></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">2）KPI：是衡量网络质量和用户感知的重要指标，常用分析指标<span style="color: black;">包含</span>FTP下载速率。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">3）DT（DRIVE TEST）测试与分析优化：<span style="color: black;">重点</span><span style="color: black;">包含</span>覆盖分析、干扰分析、切换分析、掉话分析、未接通分析、射频优化<span style="color: black;">调节</span>、频率及参数<span style="color: black;">调节</span>等。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">3.3 优化调试</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">1）<span style="color: black;">处理</span>场强覆盖问题操作要点</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">a.<span style="color: black;">调节</span>天馈参数，<span style="color: black;">调节</span>天线下倾角和方位角；</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">b.<span style="color: black;">调节</span>覆盖小区的发射功率，<span style="color: black;">掌控</span>覆盖范围；</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">c.<span style="color: black;">调节</span>网络切换参数，让终端在弱覆盖小区内尽快切出；</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">d.更换天线，<span style="color: black;">按照</span>问题更换高增益<span style="color: black;">或</span>低增益的天线；</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">e.若覆盖有<span style="color: black;">很强</span>盲区，应在相邻基站中间新<span style="color: black;">增多</span>基站。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">2）<span style="color: black;">处理</span>切换问题操作要点</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">a.邻区漏配，<span style="color: black;">引起</span><span style="color: black;">没法</span>找到<span style="color: black;">目的</span>小区而<span style="color: black;">引起</span>切换失败；</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">b.切换不<span style="color: black;">即时</span>可<span style="color: black;">经过</span><span style="color: black;">调节</span>切换<span style="color: black;">关联</span>参数：切换门限、迟滞、切换延迟触发时间、CIO等来<span style="color: black;">掌控</span>切换<span style="color: black;">机会</span>；</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">c.覆盖不<span style="color: black;">恰当</span>（弱覆盖、越区覆盖等）易<span style="color: black;">引起</span>切换失败<span style="color: black;">或</span>掉话，需要<span style="color: black;">经过</span>天线<span style="color: black;">调节</span>、功率<span style="color: black;">调节</span>等手段来<span style="color: black;">掌控</span>信号覆盖范围。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">3）<span style="color: black;">处理</span>干扰问题操作要点</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">a.排除硬件故障，如天线故障、馈线损坏、进水等；</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">b.GPS<span style="color: black;">区别</span>步；</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">c.天线高度、方向角、下倾角的<span style="color: black;">调节</span>；</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">d.优化导频功率、PCI规划等；</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">e.应对带状覆盖，<span style="color: black;">运用</span>窄波束天线；</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">f.排除设备内部互调干扰；</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">e.排除外界无线信号干扰。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><strong style="color: blue;"><span style="color: black;">4 结束语</span></strong></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">LTE网络服务质量测试和网络优化<span style="color: black;">办法</span>，<span style="color: black;">已然</span>在国内某重载铁路LTE系统上进行应用。综上所述，<span style="color: black;">经过</span>对无线场强覆盖、车地通道性能以及切换性能等关键参数的测试，客观<span style="color: black;">评定</span>列车高速移动状态下的网络性能指标，<span style="color: black;">亦</span>为无线网络优化<span style="color: black;">供给</span>可信数据依据，使铁路专用的LTE无线宽带通信系统的工程质量得到有效<span style="color: black;">保证</span>。</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><strong style="color: blue;"><span style="color: black;">参考文献</span></strong></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">张文，李士寒.Gsm-r无线通信网络服务质量测试系统及<span style="color: black;">办法</span>：ZL200810037802.4.2003-6-26.</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">王玉强，王立国.GSM-R网络承载列控业务时的质量<span style="color: black;">评估</span><span style="color: black;">办法</span>.铁道通信信号，2007，43（3）：48-50.</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;"> 窦超，段正.LTE网络质量和业务服务质量的<span style="color: black;">评估</span>体系<span style="color: black;">科研</span>.现代电信科技，2015，45（3）：1-6.</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">卢鑫，华尧.基于TD-LTE的高速铁路宽带通信系统集成测试.铁路通信信号工程技术，2013，10（S1）：127-130.</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">周宇晖，李雪，马丽兰.简谈铁路LTE服务质量指标参数<span style="color: black;">科研</span>.铁路通信信号工程技术，2015（5）：33-36.</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">王芳，邸士萍.LTE-R系统架构<span style="color: black;">科研</span>.铁路通信信号工程技术，2016，13（6）：23-26.</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">吴育辉，张满姣，刘立才.LTE网络服务质量<span style="color: black;">保证</span>机制<span style="color: black;">科研</span>.通信技术，2017，50（8）：1752-1756.</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">赵隽琪，思博伦.LTE端到端业务质量测试<span style="color: black;">处理</span><span style="color: black;">方法</span>.电信网技术, 2011（2）：70-73.</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">邹引.LTE-R承载列车<span style="color: black;">掌控</span>类业务服务质量指标<span style="color: black;">科研</span>.北京:北京交通大学，2016.</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">（收稿日期：2017-11-03）</span></p>
<p style="font-size: 16px; color: black; line-height: 40px; text-align: left; margin-bottom: 15px;"><span style="color: black;">（修回日期：2017-12-10）</span></p><span style="color: black;"><span style="color: black;">更加多</span>精彩 欢迎关注</span>
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