6.1 Introduction

23.2213GPPArchitectural requirementsRelease 17TS

From a Mobility Management point of view, the CN encompasses two domains, a CS domain and a PS domain. The UTRAN and the GERAN can be connected either to both these CN domains or to one of the CN domains. The E-UTRAN connects with the PS domain only.

A single RRC connection (between RAN and UE) shall carry all user plane and signalling flows to/from a UE. This is regardless of where in the CN they originate/terminate.

The 3GPP specifications for UTRAN and GSM in Iu mode shall support compatibility with GSM networks in A/Gb mode from the point of view of roaming and handover. The 3GPP specifications for EPS support compatibility with GSM networks and with UMTS from the point of view of roaming and handover. For the LM/MM functionality point of view this implies among other things the following:

a) IMSI shall be used as the common user identity in the two CN domains;

b) common MAP signalling is applied to networks supporting either Iu or A/Gb mode or both.

c) radio network parameters and radio resource management should be isolated in the RAN.

The LM/MM techniques used should minimise radio resource usage of the RAN.