what is nsa mode in 5g

5G NSA (Non-Standalone) mode is a type of operation for 5G networks that relies on a connection to a 4G LTE network. In NSA mode, the 5G radio access network (RAN) operates on a legacy 4G LTE core, known as the Evolved Packet Core (EPC), and manages control plane functions. NSA includes both a 4G and 5G base station, but the 4G base station takes precedence. Because the NR control plane anchors to the EPC, radio frequency signals forward to the primary 4G base station. NSA is considered the first stage of 5G and can serve as a steppingstone for carriers unprepared to make a hefty investment when transitioning from legacy 4G LTE to 5G networks. Devices running Android 10 or higher can support 5G NSA, and they can display a 5G icon on the status bar when connected to a 5G network. In contrast, Standalone (SA) mode is an end-to-end 5G network with both a 5G RAN and NR core.