The radio access network (RAN) has been in use since the beginning of cellular technology and has evolved through the generations of mobile communications (1G, 2G, 3G, 4G, and in anticipation of the forthcoming 5G). Components of the RAN include a base station and antennas that cover a given region depending on their capacity.
Radio Access Network Basics
In a RAN, radio sites provide radio access and coordinate management of resources across the radio sites. A device is wirelessly connected to the core network, and the RAN transmits its signal to various wireless endpoints, and the signal travels with other networks’ traffic.
Two types of radio access networks are Generic Radio Access Network (GRAN), which uses base transmission stations and controllers to manage radio links for circuit-switched and packet-switched core networks; and GSM Edge Radio Access Network (GERAN), which supports real-time packet data. Two other types of radio access networks are UMTS Terrestrial Radio Access Network (UTRAN), which supports both circuit-switched and packet-switched services; and Evolved Universal Terrestrial Radio Access Network (E-UTRAN), which focuses only on packet-switched services. E-UTRAN also provides high data rates and low latency.
Radio Access Network Controller
The RAN’s controller controls the nodes that are connected to it. The network controller performs radio resource management, mobility management, and data encryption. It connects to the circuit-switched core network and the packet-switched core network, depending on the type of RAN.
Today’s RAN architectures — particularly in digitally transformed networks — separate the user plane from the control plane into different network elements. In this scenario, the RAN controller can exchange user data messages through one software-defined networking (SDN) switch, and a second set with base stations via a second control-based interface. This separation of the control plane and data plane will be an essential aspect of the flexible 5G radio access network, as it aligns with SDN and network functions virtualization (NFV) techniques such as service chaining and network slicing.
Radio Access Network Evolution
Radio access networks have experienced much evolution since their origins, to the point at which today’s radio access networks support multiple-input, multiple-output (MIMO) antennas, large spectrum bandwidths, multi-band carrier aggregation, and so on — all of which bodes well for the 5G future.