What is RRH (Remote Radio Head), How it is connected to BBU (Base Band Unit) ?

RRH是个啥？它是怎么与BBU连接的？

July 14, 2017adminLTE, RF Basics, Tech Fundas

The remote radio head (RRH) contains the base station’s RF circuitry plus analog-to-digital or digital-to-analog converters and up/down converters.

RRH是无线拉远设备，其中包括与基站连接的电路、模-数和数-模以及上、下行转换器模块；

         图1.RRH结构示意图

It is sitting on top of cell tower that mainly performs following functions:

RRH安装在铁塔上，具体有以下功能：

• Convert optical signal to electrical signal and   vice versa using CPRI

• 通过CPRI进行光信号与电信号相互转换；

• In transmitter section of RRH, it convert digital   signal to RF and amplifies that signal to the desire power level and    Antenna connected to it, radiates the RF signal in air

• RRH发射模块进行数字信号与无线电波转换、放大；与天线连接将无线信号发送到空中；

• In Receiver section of RRH, it receives the desired   band of signal from antenna and amplify it.

• RRH接收模块，通过天线接收预设波段的信号并放大；

• And convert RF signal back to digital signal in the  receiver chain.

• 接收端将接收到的无线信号转换成数字信号；

   

RRH has been made of RF transmitter chain and RF receiver chain which includes the ADC (Analog to digital converter), DAC (Digital to analog converter), Mixer, PA (Power amplifier), LNA (Low Noise Amplifier) etc. Basic Block diagram of RRH is as shown below:

RRH设备中包括：RF发送和接收模块，其中包括ADC(模数转换)、DAC（数模转换）电路、合路器、PA（功率放大器）、LNA（低噪声放大器）等；RRH主要模块见下图：

                           图2.RRH主要模块示意图

RRH is connected to the Base band unit (BBU) via optical cable. Optical cable is used because it has less loss and it is cheaper as compared to RF Coaxial cable.

RRH通过光纤与基带单元（BBU）连接；使用光纤是因为（比同轴电缆)损耗小、价格便宜；

One base-band unit is connected to multiple RRHs depending upon the capability of base-band unit.

根据其容量，一个基站（单元）可连接多个RRH；

                                    图3.基站多个RRH连接 

原文来自：http://www.techplayon.com/