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common public radio interface (CPRI)

CPRI, or Common Public Radio Interface, is a specification for wireless communication networks that defines the connectivity and control communications between baseband units (BBUs) and remote radio units (RRUs), also known as remote radio heads (RRHs)[1]. It was originally developed in 2004 by a consortium of five original equipment manufacturers: Nokia, Huawei Technologies, Ericsson, NEC, and Nortel, with Nortel leaving the consortium in 2005[1].

The CPRI specification provides a standardized framework for the development of equipment for mobile networks. It defines the key internal interfaces (digitized serial) between radio equipment (RE) and local/remote radio equipment controllers (RECs) in radio base stations[1]. The first version of the specification (CPRI v1.0) also defined the items for transport, connectivity, and control, including user plane data, control plane transport mechanisms, and synchronization methods[1].

CPRI is often used to replace a copper or coax cable connection between a radio and a base station, allowing the connection to be made to a remote and more convenient location[2]. This connection, often referred to as the Fronthaul network, can be a fiber to an installation where the fiber supports both single and multi-mode communication[2].

The benefits of CPRI include its flexibility and scalability for wireless radio base stations, the ability for base station manufacturers to use one common protocol, and a wide radio base station portfolio that can be easily adapted to multiple deployment scenarios[1]. The specifications are free and available to the public[1].

It's important to note that CPRI is not a standard, but a specification. Each radio equipment OEM encodes a unique adaptation of the specification to provide processing capabilities[3]. The CPRI specification only defines the key criteria for interfacing transport, connectivity, and control communications between the BBU and RRU[3].

CPRI plays a crucial role in modern telecommunications, particularly in the realm of wireless communication systems. It enables the seamless transmission of data-intensive content, including high-definition video streaming, online gaming, and large file downloads[6]. It's a linchpin in modern telecommunications networks, enabling the efficient, high-speed, and low-latency data transmission that is fundamental to our interconnected world[6].