6 Application Examples

23.2363GPPIntra-domain connection of Radio Access Network (RAN) nodes to multiple Core Network (CN) nodesRelease 17TS

This clause describes some application examples for networks using the intra domain NAS node selection. In these examples, pool-areas are depicted by boxes or ellipses, while the core network elements which serve the pool-areas are depicted by the NRIs they have been assigned.

6.1 Network configuration example 1

This example configures 9 pool-areas each with 3 CN nodes serving within a pool-area. When a MS moves from one (NRI:1,2,3) to another pool-area (NRI:4,5,6). It indicates the old NRI (3) derived from its old TMSI to the RNC in the new pool-area (NRI:4,5,6). This NRI 3 is not configured in the RNC of the pool-area (NRI:4,5,6). The RNC selects a CN node out of the available NRIs 4,5,6 and establishes the signalling connection for the MS with the selected CN node. This new CN nodes allocates a new TMSI to the MS and thereby the new NRI for the new pool-area.

In this example, the NRIs can be re-used in a pattern where adjacent pool areas do not use the same NRI. Every pool area change will initiate a new selection of a new CN node.

Figure 2: Network configuration example 1

6.2 Network configuration example 2

This example shows a network covering one city centre surrounded by residential areas. The city centre is covered by all 4 pool-areas while each of the residential areas is covered by one pool-area only. Once a MS „found" its pool-area, it will not change the pool-area while commuting between the city centre and its residential area. Each of the pool-areas is served by 5 MSCs, indicated by the 5 NRI values in the figure below, which share the load within the pool-area. Only distinct NRI values are used for the overlapping pool-areas. Therefore, a MS changing between these pool-areas will always be allocated to a new MSC by the NAS node selection function. In addition it is shown, that the NRIs can be re-used in other pool-areas as indicated in the figure by the smaller areas with only one NRI. Also at a change to these areas the MSs will always be allocated to a new MSC by the NAS node selection function as adjacent areas do not use the same NRI values.

A calculation for the possible number of subscribers in this scenario is in Annex A.1: One city centre surrounded by residential areas

Figure 3: Network configuration example 3