Common Public Radio Interface (CPRI) is a standardized protocol that defines the digital interface between the Radio Equipment Control (REC) and RF Equipment (RE) of wireless infrastructure base station. This realizes the interoperability among different supplier devices and protects the software investment of wireless service provider. CPRI is still evolving and the wire rate is also rising. At present, the latest standard V7.0 maximum operating speed (line bit rate) has been up to 24.3Gbps, so 25Gbps SFP28 optical module can meet its needs.

CPRI supports using distributed architecture. The base station comprising REC is connected to remote radio front-end (RRH or RE) via the optical fiber link carrying CPRI data. Because it is only required to install the remote radio front-end at the place with poor environment, this architecture reduces the cost of service provider. The base station can be located in the heartland with good environment, which is an area with ideal signal coverage, climate and power supply. In a typical network, several remote radio front-ends will be connected to the same base station via the topology.

BBU is baseband processing unit and RRU is radio remote unit. They are connected with each other by using digital optical modules. RRU will emit the digital baseband signals via the antenna after processing, frequency conversion, and radio filtering and radio amplification.

For CPRI wireless fronthaul networks, CloudOptics has developed a complete set of industrial-grade SFP, SFP+ and SFP28 optical transceivers. The optical interface types are optional with dual fiber and single fiber) and the maximum transmission distance is 80km.