Method and apparatus for mobility in Non-terrestrial networks

Abstract

A wireless communication system 300 comprises a first base station (e.g. serving non-terrestrial network NTN eNB 310) supporting a first network and a second base station (such as eNB wireless base station 312) supporting a second network, and a plurality of wireless communication units (User Equipments 370), wherein at least one of the first network and second network is an NTN. The first base station 310 is arranged to send a transmission 322 to at least a first UE 370 of the plurality of UEs. The transmission comprises an instruction to the at least UE to: perform a search for radio signal transmissions from eNB 312 of the second network; and perform radio signal measurements on said radio signal transmissions from eNB 312 of the second network. Serving base station 310 is able to provide an indication from the network, that may avoid UE 370 deciding to not perform any measurement and power off its access stratum functions completely. Therefore, a network (e.g. NTN) may request a UE 370 to perform measurements during discontinuous coverage. Re-directing to a discontinuous coverage NTN may occur when coverage is poor and performance better in a discontinuous network. The transmission is a System Information Block type5, SIB5, message comprising an information element that includes cell re-selection parameters that are common for a frequency and cell-specific re-selection parameters used by the at least first UE to transition to the second network and perform radio signal measurements on said transmissions from the second network.

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