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

RRH是個啥？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是無線拉遠設備，其中包括與基站連接的電路、模-數和數-模以及上、下行轉換器模塊；

         圖1.RRH結構示意圖

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進行光信號與電信號相互轉換；

• 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)射模塊進行數字信號與無線電波轉換、放大；與天線連接將無線信號發(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，通過天線接收預設波段的信號并放大；

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

• 接收端將接收到的無線信號轉換成數字信號；

   

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設備中包括：RF發(fā)送和接收模塊，其中包括ADC(模數轉換)、DAC（數模轉換）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；使用光纖是因為（比同軸電纜)損耗小、價格便宜；

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

根據其容量，一個基站（單元）可連接多個RRH；

                                    圖3.基站多個RRH連接 

原文來自：http://www.techplayon.com/