interconnection between core network and radio access?

Question

Someone can tell in context of mme how interconnection between core network and radi access ( 2G, 3G ,4G ) can be done?

Answer 1

for 4G
B/W UE and ENODEB radio interface will communicate with C-RNTI,TAI
B/W ENODEB AND MME S1-MME interface will communicate with enodeb UE S1AP ID,MMEI,ECGI,TAI

FOR internetwork(2g,3g) MME will share UE context like new/old GUTI,IMSI and security keys