user in these mini-datacenters. This architecture provides the flexibility to deploy RAN software along with packet core functions and application software within a single cloud infrastructure. One of the consequences of the move to virtualization and the change to a 5G architecture is the in- creased contribution by software and the reduction in proprietary hardware. This has generated a strong desire by the operators to move to more open systems in the RAN. These operators and many industry vendors came together and formed various alliances to define 5G RAN functions using open protocols as well as specify COTS platform features. The following section covers the most important organizations behind these evolutions in the RAN. 4.6.1 Common Public Radio Interface Common Public Radio Interface (CPRI) is a cooperation between five companies: Ericsson, Hua- wei, NEC, Nokia (previously Siemens), and Nortel. Nortel left the organization in December 2009 after contributing to the early releases of CPRI. The CPRI specification defines an interface that connects radio antennas to the 3G/4G base station. In their terminology, CPRI is a specification for the interface that connects the Radio Equipment Controller (REC) to the Radio Equipment (RE). The latest version of the CPRI specification (7.0) was published in October 2015. The terminology between different SDOs and even each generation of mobile is a cause of severe confusion for those ramping up in this field. At this point of reading, the book tends toward simplicity, avoiding some terms until later in the book. But do not be surprised to see completely different terms from different organiza- tions and to see that terminology changes for each new generation of mobile specifications. Although the layer 1 transport is standardized, the CPRI specification reserves data fields for the transmission of vendor-specific data, allowing manufacturers to customize their deployment of CPRI. Due to this vendor-specific customization, the industry regards implementations of CPRI 