Jan 29 2015
Research and Markets has announced the addition of EJL Wireless Research's new report "CPRI 6.0 Subsystem Technology Analysis-Optical Interfaces for Digital to RF Connectivity " to their offering.
At first glance, the vital link between the digital baseband unit (DU) and the remote radio unit (RRU) appears to be a typical industry standard fiber optic connection that uses standard small form factor pluggable (SFP/SFP+) fiber optic laser modules in a Base Transceiver Station system, as shown in Exhibit 1 below.
However, the transmission standard known as the Common Public Radio Interface (CPRI), or just CPRI, is far more than a typical industry standard. In fact, it defines Fronthaul and sets its parameters. Ericsson, Huawei, NEC, NSN, and Alcatel-Lucent are the current members of the CPRI cooperative (Co-Op). Collectively, they own the copyrights associated with the CPRI specification, and their continuous development of CPRI has made this specification the well-established Fronthaul interface for all Radio Base Station products as shown below.
The CPRI Co-Op is now working on increasing efficiency through the inclusion of new features. Updates on these features are available when they publish newer versions of the CPRI specification.
While the CPRI Co-Op's work is an ongoing effort to increase CPRI efficiency, and enhance features and capabilities, the release of a new specification itself does not provide the necessary CPRI Subsystem detail or context to ensure its proper implementation. Instead, this report provides the necessary CPRI subsystem insight for guiding successful use of CPRI in the years to come.
During our extensive research into the specification and the entire CPRI ecosystem it spawned, we uncovered an incredible mix of interdependencies between ASICs, FPGAs, and other components that comprise a CPRI subsystem. Ultimately, these components must become fully compliant with the CPRI Specification.
By definition and assertion, the CPRI specification applies to any RE or REC that includes an interface compliant with the specification. The evolution of CPRI has not deviated too far from its scope as defined in its first published version based on its physical layer (Layer 1) supporting both an electrical and optical interface for remote radio equipment, with a Layer 2 that shall support flexibility and scalability.
The definitive stand on the use of CPRI over Ethernet (CoE) comes from the Metro Ethernet Forum (MEF) Mobile Backhaul Implementation Agreement (IA). [MEF 22.1.1, Mobile Backhaul Phase 2, Amendment 1Small Cells, July 2014.] Its Section 4.1.1 Radio Coordination lists coordination requirements from no coordination to very tight coordination. Both Fronthaul and CPRI have very tight coordination requirements. This level of coordination is out of scope for the current IA, because MEF Ethernet Services cannot currently support the fronthaul of CPRI.