How to know if the BTS is 2G or 3G or 4G or 5G? the RAN evolution in mobile cellular network

A mobile cellular network is composed of three main parts, User Equipment (UE), Radio access network (RAN), core network (CN) and other external networks (e.g. internet).

• User Equipment (UE) have traditionally corresponded to mobile phones, smartphones and tablets, but will increasingly include cars, drones, industrial and agricultural machines, robots, home appliances, medical devices, and so on.

• Radio access network (RAN) connects individual devices to other parts of a network through radio connections. The RAN includes a base station and antennas that cover a specific region according to its capacity, design and propagation.

• Core network (CN) provides coordination between different parts of the access network and also provides connectivity to the internet.

• Transport network provides connectivity between the RAN and the CN.

This article focuses on the changes in RAN in mobile networking evolution from 2G through 5G. 

The RAN includes a base station and antennas that cover a specific region according to its capacity, design and propagation. 

In the 2G GSM network, the RAN is composed of several BTSs(Base Transceiver Station) and one BSC(base station controller).

• BTS is responsible for managing all the radio communication between a mobile handset and the mobile network. 

• BSC usually controls a number of BTSs. BSC has the intelligence to manage mobile radio resources, and it controls tasks such as handover and frequency allocation. A BSC also functions as a "funneler". It reduces the number of connections to the Mobile Switching Center (MSC) and allows for higher capacity connections to the MSC.

Node B and RNC collectively represent the 3G UMTS radio access network.

• Node B is the base station in 3G networks. Node B communicates with the mobile handsets just like BTS does in a 2G GSM network. 

• Radio Network Controller (RNC) is the 3G equivalent of BSC. It controls Node B and carries out radio resource management, some mobility management functions and encrypts data before it is sent to and from the mobile. The RNC establishes a connection between the 3G radio access network and the 3G mobile core.

In 4G LTE network, eNodeB is the main component of the E-UTRAN radio access network.

• The base stations in 4G LTE networks are called evolved Node B or eNodeB.

• eNodeB has an additional role as the radio network controller in 4G LTE networks, in addition to creating mobile network coverage. It means that for LTE, eNodeB is able to perform as equivalent to what Node B and RNC do together in 3G UMTS.

In the 5G NR network, the base station is in the form of NodeB (or gNB), replacing the eNodeB in 4G LTE..

• Unlike 4G, 5G base stations are split to CU (centralized unit) and DU (distributed unit). This is a major change in network architecture.

• The base station takes digital packets from the network core (typically the EPC) and synthesises the radio signals for transmission.

• Modern eNodeB and gNodeB base stations typically use Software Defined Radio (SDR) for this purpose.