无线传播及链路预算

1、无线传播、无线传播、CDMACDMA链路预算链路预算hmhdRH无线链路组成接收机接收机天线天线天线天线传输线传输线发信机发信机传输线传输线l 功率输出功率输出l 调制类型调制类型l 频谱密度频谱密度l 传输线损耗传输线损耗l 增益、带宽增益、带宽l 波束宽度波束宽度l 极化极化l 路径损耗路径损耗l 增益、带宽增益、带宽l 波束宽度波束宽度l 极化极化l 传输线损耗传输线损耗l 灵敏度灵敏度l 扩频增益扩频增益l 编码增益编码增益l 动态范围动态范围基本传播模型z自由空间y信号衰减 20 dB/ 10倍距z反射y反射波180相位反向，对直射波有抵消作，减少了接收功率y信号衰减 30-40 d

2、B/ 10倍距，10 dB /2倍距z绕射y直射波被挡住y有附加损耗绕射绕射部分反射部分反射BAdD自由空间自由空间信号衰减信号衰减-距离的关系距离的关系-40-30-20-100Distance, Miles13.1610257 862倍距(2x)10倍距(10 x)衰减电平BALddr22tt)4(GGP)Pr(220)()(ddodPdPrr)log(20)()log(20)()(000dddBPLdddBmdPdBmdPrr-kmdMHzfLGGdfdPPdBPLrtrt:,:) 1, 1, 1(log20log2045.32)4(log10log10)(222馈线损耗接收天线增益发射

3、天线增益ddBMHzPLlog205 .90)800()log(2098)9 . 1 (ddBGHzPL自由空间：距离或频率增加一倍，路径损耗增加 6dBdPtPr自由空间传播自由空间传播各种环境下的传播各种环境下的传播z 被阻挡y电波被吸收=附加损耗y反射电波=时延z 多径传播y移动环境y各种多径具有随即幅度和相位y信号在时间上被扩展z 建筑/汽车穿透损耗y衍射，附加损耗y用统计预测y概率=可靠接收建筑建筑/汽车的穿透汽车的穿透有阻挡有阻挡RFD多径传播多径传播 多径传播影响多径传播影响z 信号电平随用户移动而变化z 慢变化-来自于建筑物或山地形的遮挡z 快衰落-多径产生不同的相位y相位相反

4、，衰落最深y衰落间隔 /2 :187 mm 800 MHz.79 mm 1900 MHzy称为Rayleigh 衰落, 瑞利统计模型At10-15 dBRayleigh 衰落衰落多径传播多径传播穿透损耗穿透损耗z 主要机制：衍射.z 计算方法：统计建筑物穿透建筑物穿透汽车穿透汽车穿透?建筑物穿透损耗典型值密集城区城区郊区乡村20 dB15 dB10 dB6 dB开阔地0 dB传播模型传播模型z 数学模型z 实地测量z 模型修正n 公式分析公式分析 自由空间 (Friis) 反射抵消n 分地形区域分地形区域 Hata Cost-231n 点到点物理分析点到点物理分析 Ray Tracing- L

5、ee Method, others Tech-Note 101 Longley-Rice, Biby-Cn 考虑衰落、穿透考虑衰落、穿透 Rayleigh 分布 Normal 分布水平距离水平距离垂直距离垂直距离HataHata模型、模型、COST-231COST-231模型模型z仅考虑区域，没有细分路径，单个路径会相差较大。z须输入y频率y距离y天线有效高度y地形地貌（城市、郊区、农村、等）RSSI, dBm-120-110-100-90-80-70-60-5003691215 182124 273033Distance from Cell Site, kmFieldStrength,dBu

6、V/m+90+80+70+60+50+40+30+20n绿色线绿色线n 路测结果路测结果 n红色线红色线n Hata 模型模型预测结果预测结果Hata ModelPL (dB) = 69.55 + 26.16 log (F) - 13.82 log(H) + (44. 9 - 6.55 log(H) )*log (D) + CHata ModelPL：路径损耗F： 频率，单位MHz (150 - 1500 MHz)D： 距离，单位kmH： 基站天线有效高度，单位mC： 环境校正因子；取值：密集城区：0 dB城区：- 5 dB郊区：- 10 dB农村：- 17 dBCOST-231PL (dB)

7、 = 46.3 + 33.9*logF - 13.82*logH + (44.9 - 6.55*logH)*log D + CCOST-231PL：路径损耗F： 频率，单位MHz (1500 - 2000 MHz)D： 距离，单位kmH： 基站天线有效高度，单位mC： 环境校正因子；取值：密集城区： -2 dB城区： -5 dB郊区： -8 dB农村： -10 dB开阔地： -26 dB路径损耗表格速查路径损耗表格速查d d密集城区密集城区城区城区郊区郊区乡村乡村开阔地开阔地密集城区密集城区城区城区郊区郊区乡村乡村开阔地开阔地1123.35118.35113.35106.3595.35133.

8、31130.31127.31125.31109.311.5129.41124.41119.41112.41101.41139.37136.37133.37131.37115.372133.71128.71123.71116.71105.71143.67140.67137.67135.67119.672.5137.05132.05127.05120.05109.05147.00144.00141.00139.00123.003139.77134.77129.77122.77111.77149.73146.73143.73141.73125.733.5142.07137.07132.07125.0

9、7114.07152.03149.03146.03144.03128.034144.07139.07134.07127.07116.07154.02151.02148.02146.02130.024.5145.83140.83135.83128.83117.83155.78152.78149.78147.78131.785147.40142.40137.40130.40119.40157.36154.36151.36149.36133.365.5148.83143.83138.83131.83120.83158.78155.78152.78150.78134.786150.13145.1314

10、0.13133.13122.13160.08157.08154.08152.08136.086.5151.32146.32141.32134.32123.32161.28158.28155.28153.28137.287152.43147.43142.43135.43124.43162.39159.39156.39154.39138.397.5153.46148.46143.46136.46125.46163.42160.42157.42155.42139.428154.43149.43144.43137.43126.43164.38161.38158.38156.38140.388.5155

11、.33150.33145.33138.33127.33165.29162.29159.29157.29141.299156.19151.19146.19139.19128.19166.14163.14160.14158.14142.149.5156.99151.99146.99139.99128.99166.95163.95160.95158.95142.9510157.76152.76147.76140.76129.76167.72164.72161.72159.72143.7210.5158.49153.49148.49141.49130.49168.44165.44162.44160.4

12、4144.4411159.19154.19149.19142.19131.19169.14166.14163.14161.14145.1411.5159.85154.85149.85142.85131.85169.80166.80163.80161.80145.8012160.49155.49150.49143.49132.49170.44167.44164.44162.44146.4412.5161.10156.10151.10144.10133.10171.05168.05165.05163.05147.0513161.68156.68151.68144.68133.68171.64168

13、.64165.64163.64147.6413.5162.25157.25152.25145.25134.25172.20169.20166.20164.20148.2014162.79157.79152.79145.79134.79172.74169.74166.74164.74148.7414.5163.31158.31153.31146.31135.31173.27170.27167.27165.27149.2715163.82158.82153.82146.82135.82173.77170.77167.77165.77149.7715.5164.31159.31154.31147.3

14、1136.31174.26171.26168.26166.26150.2616164.78159.78154.78147.78136.78174.74171.74168.74166.74150.7416.5165.24160.24155.24148.24137.24175.20172.20169.20167.20151.2017165.69160.69155.69148.69137.69175.64172.64169.64167.64151.6417.5166.12161.12156.12149.12138.12176.08173.08170.08168.08152.0818166.54161.54156.54149.54138.54176.50173.50170.50168.50152.5018.5166.95161.95156.95149.95138.95176.91173.91170.91168.91152.9119167.35162.35157.35150.35139.35177.31174.31171.31169.31153.3119.5167.74162.74157.74150.74139.74177.69174.69171.69169.69153.6920168.12163.1