5G and Cloud technologies are driving new Radio Access Network (RAN) architectures referred to as Centralized RAN (C-RAN). In the C-RAN architecture, the mobile base station is split into two units – a) a centralized baseband unit hosted at a data center that can carry out cost and energy efficient processing of common functions such as packet inspection, security, header compression etc, and b) remote distributed units that integrate the PHY and MAC layer functions with the radio antenna and could be installed at the street level. The two units can be separated by a distance of up to 20 km over a “fronthaul" connection and uses an emerging protocol called Common Public Radio Interface (CPRI).

With the recent release of eCPRI specifications, the use of packet transport technologies such as Ethernet is now possible over fronthaul. Thus a common cost-efficient Ethernet based network can be used for transporting both eCPRI traffic as well as data traffic from other network applications (e.g., fixed-line networks). Ethernet also offers additional advantages in terms of the use of advanced OAM mechanisms for operations, administration and maintenance of the network. Newer applications such as Mobile Edge Computing (MEC) can be moved to the distributed edge and support advanced capabilities for video analytics, location-based services and IoT (Internet of Things) resulting in further reduction in backhaul bandwidth requirements.

Tejas optical products support CPRI interfaces for optical fiber communication from baseband to remote radio-heads over both short spans (less than 2 km) and over longer distances (up to 20 km). As a result fiberized cell sites can seamlessly integrate packet optical transmission with 4G/4G+ mobile broadband access with the added benefit of unified OAM, reduced space requirements and greater power savings.