# Cellular Network Architecture ## What is Cellular Network Architecture Cellular network architecture describes how the different components of a mobile network are organized and interconnected to provide coverage and services to mobile devices. The architecture has evolved significantly with each generation of cellular technology, becoming more sophisticated to support higher data speeds, lower latency, and more efficient use of spectrum. ## Radio Access Network The Radio Access Network, or RAN, is the part of the cellular network that connects mobile devices to the core network through wireless radio links. The RAN consists of base stations, called eNodeB in LTE and gNodeB in 5G, that contain the radio antennas and electronics that communicate with mobile devices. In older networks, each base station had a controller that managed a group of base stations. In modern LTE and 5G networks, some of these control functions have been moved into the base station itself. ## Core Network The core network is the central part of the cellular network that provides the switching, routing, and management functions. In LTE, the core is called the Evolved Packet Core or EPC. The core network authenticates users, assigns IP addresses, routes data to and from the internet, provides mobility management to track where users are as they move between cells, and handles billing and quality of service. In 5G, the core network is redesigned with a service-based architecture that uses cloud-native technologies. ## Fronthaul and Backhaul Backhaul connects base stations to the core network. This connection must carry all the traffic generated by all devices served by the base station. Fronthaul, used in virtualized RAN architectures, connects a remote radio unit at the antenna site to a centralized baseband processing unit. The split allows baseband processing to be centralized and shared among many radio sites. ## Voice and Data Services Early cellular networks were designed primarily for voice calls. Data services were added later. In modern LTE and 5G networks, all traffic including voice is carried as data packets using IP. Voice over LTE, or VoLTE, provides high-quality voice calls over the LTE data network. 5G extends this to Voice over New Radio.