移动通信系统中光纤直放站的设计

移动通信系统引入光纤直放站后使基站接收端的噪声发生变化，通过对光纤直放站之间的传输距离分析以及引入光纤直放站后基站接收端的噪声变化分析发现，噪声增量主要由直放站增益和基站发射机至直放站的路径损耗决定，并进一步推导出光纤直放站的上行增益应比路径损耗小8 dB，而其下行增益的设计应充分考虑到系统上下行的平衡。最后，设计了系统噪声系数为3 dB，上行增益为30 dB，下行输出功率设为36 dBm的光纤直放站。实际投放后发现，网络盲区的比例减小到3.18%，说明该直放站的效果相当显著，并且性能稳定，与原基站兼容性好。

Designing of Light Fiber Repeater in Mobile Communication System

The noise of receiving end in mobile communication systems will change after the introduction of fiber optic repeater station.Through the analysis of the noise transmission distance between the fiber optic repeater and the noise change of the receiving end after introduction of fiber optic repeater station,it was found that the noise increment was mainly decided by repeater gain and the path loss from repeater to base station transmitter.Further,it was deduced that the fiber optic repeater uplink gain should be smaller than loss path by 8 dB,and its downstream gain should be designed to fully take into account the balance of the system up and down the line.Finally,a set of fiber optic repeater were designed with the system noise figure of 3 dB,uplink gain of 30 dB,and downlink power of 36 dBm.After actual delivery,it was found that the proportion of the network blind reduced to 3.18%,indicating that the repeater has quite remarkable effect,stable performance,and good compatibility with the original base.