Content for  TR 22.835  Word version:  18.2.0

For a flexible and dynamic management, a network slice used for broadcast services can be provided over a dedicated frequency band. For example, in a specific frequency band or in a specific region, only sessions for broadcast can be allowed while all other unicast sessions are not allowed. This may trigger various deployment scenarios where third parties such as broadcasters may create their own network slices and the mobile operator packs these network slices into a specific dedicated frequency band. Typically, for broadcast service, all or most traffic flows in downlink direction only. This characteristic may fit well to some frequency spectrum allocation and can increase utilization ratio of frequency spectrum.

An operator OPM owns a bunch of spectrum. One of the spectrum is FB1, and this is an unpaired spectrum, e.g. downlink only spectrum. The other spectrum is FB2 and this spectrum supports both downlink and uplink. OPM decides to dedicate spectrum FB1 for broadcast service slices. Because, services over broadcast service slices are broadcast/multicast service which does not generates UL traffic. For example, TV service is best suited for this broadcast service slice. The operator OPM also provides network slices for unicast traffic services, and this network slices are configured to use frequency band FB2, because FB2 is a paired spectrum which supports both UL traffic and DL traffic. With OPM, a UEa has a subscription for the broadcast service slice, and also for a unicast traffic service slice. This UEa does not support simultaneous operation over FB1 and FB2 due to capability limitation. Thus, while the UE engaged in the broadcast service slice, the QoS over a unicast service slice may degrade or may stop.

Following is service flow for this use case:

• User of UEa starts browsing internet contents. The internet traffic for the browsing is transported over unicast network slices, which is configured to use FB2.
• The user discovers that a famous TV show is ongoing and he/she has a subscription for that. The user launches a TV application, which uses broadcast service slice. Now, the user does not use browsing application anymore because the user now watches TV service.
• Because the broadcast service slice is provided over FB1, the UEa tunes to that frequency band.
• The UEa starts to receive traffic for TV show via the broadcast service slice.
• While the user is watching the TV show delivered over broadcast service slice, an incoming call is notified. From the phone number information, the user identifies it as a Robocall and decides not to take the call. In this step, i.e., while the UEa is engaged in the notification procedure of incoming call, the quality of experience of broadcast service slice is not degraded. I.e., there is no noticeable interruption of TV show.
• Later, a friend of the user makes a phone call to the user. An incoming call is notified to the user who is in the middle of watching a TV program.
• Once the user decides to take the phone call, the UEa may suspend TV application. I.e, the use of broadcast slice is suspended.

The user ends TV reception and starts voice call with his/her friend.

Following are existing requirements specified in TS 22.261: These existing requirements specify the case where the UE access simultaneous access multiple network slices. However, the assumption here is that the UE can support multiple frequency spectrum simultaneously. If the UE cannot support multiple frequency bands and if each frequency band supports different network slices, the UE cannot simultaneously use network slices on different frequencies. For this UE, the UE can use multiple network slices only when the network slices are on the same frequencies. In the service flow in the previous section, the UE has limited capability so that the UE cannot support simultaneous reception/transmission on multiple frequency bands. And, this has not been addressed by existing service requirements. The ability for a 3rd party to configure a network slice is already supported in TS 22.261, including configuring the direction (e.g., uplink only, downlink only, both) of supported traffic. Similarly, requirements to avoid interference between network slices are already included in TS 22.261.

N/A

Relay nodes can be used to provide extended coverage for a UE located in area where radio signal from radio access network is weak. Also, relay nodes can be used to reduce power consumption of UEs. When a user traffic generated by a UE is relayed by relay nodes, the radio resources used between the relay nodes and gNB can be different from the radio resource used between the relay nodes and the UEs. In most cases the relay node is more capable than the UE. E.g., it can support more different frequency ranges or support simultaneous use of different frequency bands.

Figure 5.13.2-1 shows the use case scenario where there are two possible frequency bands between the UEs, the intermediate nodes and gNBs.

In this Figure, it is assumed that

• UEs and intermediate nodes:
  • UE A1 and A2 have subscription to slice N.
  • R1 and R2 are intermediate nodes. These intermediate nodes can be IAB-nodes. Both are authorized to relay traffic for any network slice.
  • Intermediate node R1 is configured to use F2 toward UEs, while intermediate node R2 is configured to use F1 toward UEs. The link between the intermediate node R1/R2 and NG-RAN can use either F1 or F2 or both.
  • UE A1 is within coverage of R1 and UE A2 is within coverage of R2.
• Deployment:
  • Slice N is configured to use Frequency F2.
  • Slice M is configured to use Frequency F1.

Following is service flow for this use case:

• The UE A1 and A2 are out of coverage. After power-on, these UEs start search for potential intermediate nodes.
• Intermediate nodes R1 and R2 are operational. R1 provides connectivity service to UEs via F2 and R2 provides connectivity service to UEs on F1. Both are connected to gNB.
• The UE A1 detects intermediate node R1 on frequency F2, and establishes connection toward R1. Because the network slice N is configured to use F2, the UE A1 transmits and receives user traffic of network slice N to/from the intermediate node R1 over frequency band F2. Because the link between R1 and NG-RAN is backhauling link, the user traffic for the UE A1 for the network slice N can be transported either F1 or F2 over the link between intermediate node R1 and gNB.
• The UE A2 detects intermediate node R2 on frequency F1, and establishes connection toward R2. Because the network slice N is configured to use F2, the UE A2 does not transmit and receive user traffic of network slice N to/from the intermediate node R2.

UE A1 is provided with network service for the network slice N. UE A2 is not provided with network service for the network slice N.

Following are existing requirements specified in TS 22.261: The existing requirement talks about the criterion that is used by a remote UE for relay selection. However, it does not describe the radio resource usage restriction or configuration. Thought the service flow in the previous section discusses some aspect of relay selection, the focus is the radio resource restriction that can be put in place when relay functionality is used. The existing requirements do not clarify whether restriction on frequency resource for a network slice also applies in case the relay is used.

Following new requirements can be derived from this use case: [PR.5.13.6-1]