Applications using Network Slice(s) offered on different radio resources may be used differently in location and time. This brings motivation for the 5G System to support a mechanism to establish and manage a preference ordering among subscribed applications/services for use in cell (re)selection.
Application preference could be set by the user or derived based on the user's application usage pattern. Application preference information in the network can be overridden by application activation, such that activating an application with a lower preference order may trigger a change in serving network slice (assuming no other application is also active on that slice) and cell (re)selection if the newly activated application requires a different radio resource.
Slice M & Slice N are two slices provided by the same Operator. Services from Slice M are provided over frequency band FR1 and services from slice N are provided over frequency band FR2.
Slice M provides VPN and streaming services while slice N provides VPN and AR/VR-Gaming services. The UE's shown in the illustration have subscriptions to applications provided by both the slices M and N. The key difference in network slice selection lies in the application preference order used by each UE.
Rama and Krishna work in different companies at the same location (e.g., an office building). Rama has a WFH (Work from Home) option which he can use frequently while Krishna does not have a WFH option from his company but may be allowed WFH in rare situations. Both their homes are located in the same service area. Rama likes to use his AR/VR-Game application during office-breaks while at the office. Krishna mostly uses his streaming service during office-breaks while at the office. Both use their streaming service application most after office hours when at home.
Rama (UE1) and Krishna (UE2) have subscriptions to applications VPN, AR/VR-Game and a streaming service.
Rama has his preference profiles set in the following order:
5.8.3 Service Flows Word‑p. 23
For a normal working day at the office, Rama's UE selects slice M and Krishna's UE selects slice N based on their preferences.
Figure 5.8.3-1: Applications preferred network slices for Rama and Krishna during Workdays (Working Hours)
Both return to their homes after office hours. Both Rama's UE and Krishna's UE select slice M based on their preferences.
Figure 5.8.3-2: Applications preferred network slices for Rama and Krishna during Evenings (off-Working Hours)
During a WFH Day for Rama, he changes his profile setting to use 'WFH Profile'. While Krishna goes to office as usual. Rama's UE stays on slice M instead of switching to Slice N while Krishna's UE selects slice M as usual at the office.
Figure 5.8.3-3: WFH Scenario for Rama and normal work day for Krishna.
Once, both Rama and Krishna meet at a conference and become friends. Rama invites Krishna to join him to play an AR/VR game during office-breaks. Krishna accepts the invitation and subsequently starts playing the AR/VR game during office-breaks instead of watching his streaming service. Initiating the AR/VR-Gaming application triggers Krishna's UE to use the least preferred application during his office breaks and causes it to (re)select a cell offering Slice N
Figure 5.8.3-4: Slice Switch Triggered for Krishna due to AR/VR-Game usage
The 5G System now derives/updates the new preference for Krishna based on AR/VR-Game Usage during office breaks.