Section: J.4 Downlink data transfer
Content: Figure J.4-1 shows a downlink data transfer to an idle state UE when ISR is activated. The Serving GW receives downlink data. Because of activated ISR, the Serving GW has control connections with both MME and SGSN and sends therefore downlink data notifications to both nodes. MME and SGSN start their paging procedures, which results in paging of the UE in the registered RA and TA(s) in parallel. In the example illustrated in Figure J.4-1 it is assumed that the UE camps on E-UTRAN. So the UE responds to paging as usual with Service Request. This triggers the MME to setup the user plane connection between eNodeB and Serving GW. The downlink data are transferred to the UE. When the UE camps on UTRAN/GERAN it performs the paging response as specified for these access systems without any required update or other signalling before. The downlink data are then transferred via UTRAN/GERAN to the UE. Figure J.4-1: Downlink data transfer with ISR active