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

RRH是個(gè)啥？它是怎么與BBU連接的？

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是無線拉遠(yuǎn)設(shè)備，其中包括與基站連接的電路、模-數(shù)和數(shù)-模以及上、下行轉(zhuǎn)換器模塊；

         圖1.RRH結(jié)構(gòu)示意圖

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

RRH安裝在鐵塔上，具體有以下功能：

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

• 通過CPRI進(jìn)行光信號(hào)與電信號(hào)相互轉(zhuǎn)換；

• 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發(fā)射模塊進(jìn)行數(shù)字信號(hào)與無線電波轉(zhuǎn)換、放大；與天線連接將無線信號(hào)發(fā)送到空中；

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

• RRH接收模塊，通過天線接收預(yù)設(shè)波段的信號(hào)并放大；

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

• 接收端將接收到的無線信號(hào)轉(zhuǎn)換成數(shù)字信號(hào)；

   

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設(shè)備中包括：RF發(fā)送和接收模塊，其中包括ADC(模數(shù)轉(zhuǎn)換)、DAC（數(shù)模轉(zhuǎn)換）電路、合路器、PA（功率放大器）、LNA（低噪聲放大器）等；RRH主要模塊見下圖：

                           圖2.RRH主要模塊示意圖

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通過光纖與基帶單元（BBU）連接；使用光纖是因?yàn)椋ū韧�軸電纜)損耗小、價(jià)格便宜；

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

根據(jù)其容量，一個(gè)基站（單元）可連接多個(gè)RRH；

                                    圖3.基站多個(gè)RRH連接 

原文來自：http://www.techplayon.com/