A Radio Access Technology or (RAT) is the underlying physical connection method for a radio based communication network. Many modern mobile phones support several RATs in one device such as

Bluetooth Bluetooth is a short-range wireless technology standard that is used for exchanging data between fixed and mobile devices over short distances and building personal area networks (PANs). In the most widely used mode, transmission power is limit ...

Wi-Fi Wi-Fi () is a family of wireless network protocols, based on the IEEE 802.11 family of standards, which are commonly used for local area networking of devices and Internet access, allowing nearby digital devices to exchange data by radio w ...

, and GSM,

UMTS The Universal Mobile Telecommunications System (UMTS) is a third generation mobile cellular system for networks based on the GSM standard. Developed and maintained by the 3GPP (3rd Generation Partnership Project), UMTS is a component of the In ...

, LTE or

5G NR 5G NR (New Radio) is a new radio access technology (RAT) developed by 3GPP for the 5G (fifth generation) mobile network. It was designed to be the global standard for the air interface of 5G networks. As with 4G (LTE), it is based on OFDM. Th ...

. The term RAT was traditionally used in mobile communication network interoperability, for example, in Virtej et al., or in the example provided on the Wiki page for

radio access network A radio access network (RAN) is part of a mobile telecommunication system. It implements a radio access technology. Conceptually, it resides between a device such as a mobile phone, a computer, or any remotely controlled machine and provides co ...

. More recently, the term RAT is used in discussions of heterogeneous wireless networks. The term is used when a user device selects between the type of RAT being used to connect to the Internet. This is often performed similar to access point selection in IEEE 802.11 (Wi-Fi) based networks.

Inter-RAT (IRAT) handover

A mobile terminal, while connected using a RAT, performs neighbour cell measurements and sends measurement report to the network. Based on this measurement report provided by the mobile terminal, the network can initiate

handover In cellular telecommunications, handover, or handoff, is the process of transferring an ongoing call or data session from one channel connected to the core network to another channel. In satellite communications it is the process of transfe ...

from one RAT to another, e.g. from

WCDMA The Universal Mobile Telecommunications System (UMTS) is a third generation mobile cellular system for networks based on the GSM standard. Developed and maintained by the 3GPP (3rd Generation Partnership Project), UMTS is a component of the I ...

to GSM or vice versa. Once the handover with the new RAT is completed, the channels used by the previous RAT are released.

References

Computer networking {{Compu-network-stub