直放站的覆盖范围理论计算

1、直放站的覆盖范围理论计算直放站覆盖范围的考虑思路完全和基站一样，主要由直放站到手机的传播损耗和系统最 大允许的损耗决定，人体损耗余量、建筑物穿透损耗余量、衰落损耗余量等在直放站覆盖区 也同样要考虑进来。二者不同之处主要集中在反向链路功率预算，这里原先基站接收机的噪 声系数被直放站串联噪声系数取代。影响直放站覆盖范围的主要参数有天线类型、挂高、倾角、地形、要求的Ec/Io值、发 射功率、增益等等。在ZXRPT直放站的混合组网规划时我们已经反复考虑过了，这里提供一 组理论值用于简便快速的评估。首先考虑传播损耗，对于800MHzCDMA系统无线传播分析我们采用Okumura_Hata模型。PL(dB

2、)=69.55+26.16log(F)-13.82log(H) + (44.9-6.55log(H)*log(D)+CPL(dB)=123.3+34.42logD+C(当 F=800MHz，H=40m 时)PL(dB)=126.4+35.22logD+C(当 F=878MHz，H=30m 时)其中：PL：路径损耗，单位dBF： 频率，单位MHz(150-1500MHz)，计算取值为800MHzD：距离，单位kmH：基站天线有效高度，单位m，计算取值为40mC：环境校正因子；取值：密集城区：0 dB TOC o 1-5 h z 城区：-5 dB郊区：-10dB农村：-17dB根据以上公式计算可以

3、得出距离和路径损耗的关系。PL(dB)=69.55+26.16log800-13.82log40+ (44.9-6.55log40)*logD+C=69.55+26.16X2.9-13.82X 1.6+(44.9-6.55X 1.6) X logD+C =69.55+77-20.41+35.22X logD+C =123.3+34.42logD+Cd_1密集城区城区郊区开阔地1123.4123.3113.795.31.5129.4129.4119.8101.42133.7133.7124.1105.72.5137.1137.0127.4109.03139.8139.8130.1111.73.5

4、142.1142.1132.4114.04144.1144.1134.4116.04.5145.8145.8136.2117.85147.4147.4137.8119.45.5148.8148.8139.2120.86150.1150.1140.5122.16.5151.3151.3141.7123.37152.4152.4142.8124.47.5153.5153.5143.8125.48154.4154.4144.8126.48.5155.3155.3145.7127.39156.2156.2146.6128.19.5157.0157.0147.4128.910157.8157.8148.

5、1129.710.5158.5158.5148.9130.411159.2159.2149.6131.111.5159.9159.8150.2131.812160.5160.5150.9132.412.5161.1161.1151.5133.013161.7161.7152.0133.613.5162.3162.2152.6134.214162.8162.8153.2134.714.5163.3163.3153.7135.315163.8163.8154.2135.815.5164.3164.3154.7136.316164.8164.8155.1136.716.5165.2165.2155.

6、6137.217165.7165.7156.1137.617.5166.1166.1156.5138.118166.5166.5156.9138.518.5167.0166.9157.3138.919167.4167.3157.7139.319.5167.7167.7158.1139.720168.1168.1158.5140.120.5168.5168.5158.9140.4其次，结合系统上下行功率预算得出最大允许路径损耗。最后，把最大允许路径损耗代入传播公式求得直放站覆盖半径。举例说明：假设直放站转发天线挂高40米，下行最大发射功率为5W,直放站串联噪声系数为 FREP+3dB。先考虑直放

7、站上行覆盖范围，一般这是覆盖距离的瓶颈。标号参数密集城区城区郊区乡村开阔地不考虑余量路径损耗计算AMS 发射功率(0.2W)(dBm)2323232323EBS电缆损耗（dB）-3-3-3-3-3FBS天线增益（dBi）1717171717GMS天线增益（dBi）00000HMS电缆损耗（dB）00000直放站串联噪声系数（dB）5+35+35+35+35+3直放站接收机背景噪声（dBm）-110-110-110-110-110直放站接收机C/I（dB）-14-14-14-14-14S等效BS接收机灵敏度（dBm）-116-116-116-116-116PL1最大允许路损（未考虑余量）1531

8、53153153153路径损耗余量计算I人体损耗-3-3-3-3-3J建筑物穿透损耗-20-15-10-60K阴影衰落余量（8dB,90%/75%）-5.4-5.4-5.4-5.4-5.4软切换增益3.73.73.73.73.7干扰余量（系统负荷50%）-3-3-3-3-3PL2路损余量-27.7-22.7-17.7-13.7-7.7路径寸损耗计算结果（PL1+PL2）PL最大允许路损（考虑余量）125.3130.3135.3139.3145.3传播距离（km）（800M,hata模型）1.22.24.39.127然后考虑下行功率预算，下表是直放站在最大功率输出时，下行链路功率预算和在不同 地

9、形下的覆盖范围。标号参数密集城区城区郊区乡村开阔地不考虑余量路径损耗计算ABS发射功率(5W)(dBm)3737373737B业务信道功率78%（dB）-1.1-1.1-1.1-1.1-1.1C同时使用的业务信道数20（dB）-13.1-13.1-13.1-13.1-13.1DBTS EIRP （每个业务信道）（dBm）22.822.822.822.822.8EBS电缆损耗（dB）-3-3-3-3-3FBS天线增益（dBi）1717171717GMS天线增益（dBi）00000HMS电缆损耗（dB）00000SMS接收机灵敏度（dBm）-119-119-119-119-119PL1最大允许路损（未考虑余量）155.8155.8155.8155.8155.8路径损耗余量计算I人体损耗-3-3-3-3-3J建筑物穿透损耗-20-15-10-60K阴影衰落余量（8dB,90%/75%）-5.4-5.4-5