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Content for  TR 22.835  Word version:  18.0.0

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5.11  Interaction with Third party for network slice

5.11.1  Description

A network slice can be provided and customized based on the request of customers. For example, an application provider may want a dedicated network slice for its application and may expand or decrease the capacity of the network slices based on the dynamic demand for the application.
In other scenario, the third party itself may get and have right to use a specific frequency band. For example, by applying for local spectrum license, third party itself may own the right to use some frequency band and this frequency band can be used for a network slice and UEs dedicated to this third party.
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5.11.2  Pre-conditions

Application provider AP1 has a service agreement with operator OP1. With this service agreement, OP1 creates and runs a network slice NSz, which is dedicated for AP1. AP1 provides application App1 to its customers and this application requires very demanding QoS. Traffic generated for the application App1 are transported via NSz. Initially, frequency band FB1 with size of 50 MHz are allocated for NSz.
There is another application provider AP2, which also has a service agreement with operator OP1. With this service agreement, OP1 creates and runs a network slice NSy, which is dedicated for AP2. AP2 provides application App2 to its customers and the QoS requirement for this application is not stringent. Thus, instead of using a licensed spectrum, application provider AP2 requests the OP1 to provide network slice NSy over unlicensed spectrum, which is frequency band UFB1.
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5.11.3  Service Flows

Following is service flow for application provider AP1:
  • UEs using App1 transmit data over frequency band FB1.
  • As the App1 gets popular, the application provider decides to increase capacity for the network slice NSz. The application provider requests the operator OP1 to increase the dedicated frequency bandwidth.
  • The OP1 adjusts its 3GPP system so that additional frequency band is dedicated to support the network slice NSz.
  • Later, the application provider identifies that there is a periodicity in the usage pattern for its application. I.e., some specific time period during the day, there is a small demand for its application. So, the application provider requests to reduce the allocated frequency bandwidth for network slice NSz for a specific time period.
  • The OP1 takes into account the information from the application provider, and reduce the size of dedicated frequency during the time period.
  • Later, the application provider itself gets a right to use some specific frequency band FB2 at a certain location from authorities.
  • The application provider requests the OP1 to additionally use FB2 for network slice NSz. OP1 updates configuration for network slice NSz. From this point, OP1 keeps record usage of network slices per used frequency bands.
Following is service flow for application provider AP2:
  • Application provider requests OP1 to create network slice NSy using unlicensed frequency band UFB1.
  • When there is a user traffic for App2, the traffic is delivered over frequency band UFB1.
  • For a UE subscribes to both App1 and App2, traffic for app2 is delivered through NSy over UFB1 while traffic for app1 is delivered over other frequency bands.
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5.11.4  Post-conditionsWord‑p. 31
The UEs using App1 are served with NSz over FB2.
The UEs using App2 are served with NSy over UFB1.

5.11.5  Existing features partly or fully covering the use case functionality

Following are existing requirements specified in TS 22.261:
  • Based on operator policy, a 5G network shall provide suitable APIs to allow a trusted third-party to manage this trusted third-party owned application(s) in the operator's Service Hosting Environment.
  • Based on operator policy, the 5G network shall provide suitable APIs to allow a trusted third-party to scale a network slice used for the third-party, i.e. to adapt its capacity.
  • The 5G network shall provide suitable APIs to allow a trusted third-party to get the network status information of a private slice dedicated for the ' party, e.g. the network communication status between the slice and a specific UE.
  • Based on operator policy, the 5G network shall provide suitable APIs to allow a trusted third-party to define and update the set of services and capabilities supported in a network slice used for the third-party.
  • Based on operator policy, the 5G network shall expose a suitable API to allow an authorized third-party to define and reconfigure the properties of the communication services offered to the third-party.
  • Based on operator policy, a 5G network shall provide suitable APIs to allow a trusted third-party to create, modify, and delete network slices used for the third-party.
  • Based on operator policy, the 5G network shall provide suitable APIs to allow a trusted third-party to define and update the set of services and capabilities supported in a network slice used for the third-party.
  • Based on operator policy, the 5G network shall provide suitable APIs to allow a trusted third-party to configure the information which associates a UE to a network slice used for the third-party.
  • Based on operator policy, the 5G network shall expose a suitable API to an authorized third-party to provide the information regarding the availability status of a geographic location that is associated with that third-party.
  • Based on operator policy, the 5G network shall provide suitable APIs to allow a trusted third-party to configure the information which associates a service to a network slice used for the third-party.
These existing requirements allow interaction between the third party and the 5G system. However, these requirements do not fully address the service flow in previous section:
  • Existing requirements focused on the capability of the network slice, and not on the details of configuration, e.g. using specific resources owned by third party.
  • Existing requirements do not address restriction that can be set by third party, in using network slice.
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5.11.6  Potential New Requirements needed to support the use caseWord‑p. 32
Following new potential requirements can be derived from this use case:
[PR.5.11.6-1]
In case a third party has requested provision of a network slice using specific radio resources for the network slice, 5G system shall be able to generate charging information regarding the used radio resources e.g. used frequency bands.

5.12  Broadcast for network slice

5.12.1  Description

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.
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5.12.2  Pre-conditions

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.
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5.12.3  Service Flows

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.
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5.12.4  Post-conditionsWord‑p. 33
The user ends TV reception and starts voice call with his/her friend.

5.12.5  Existing features partly or fully covering the use case functionality

Following are existing requirements specified in TS 22.261:
  • The 5G system shall enable a UE to be simultaneously assigned to and access services from more than one network slice of one operator.
  • Traffic and services in one network slice shall have no impact on traffic and services in other network slices in the same network.
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.
  • Traffic and services in one network slice shall have no impact on traffic and services in other network slices in the same network.
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5.12.6  Potential New Requirements needed to support the use case

N/A

5.13  Relaying and backhauling data for a network slice

5.13.1  Description

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.
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5.13.2  Pre-conditions

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.
(not reproduced yet)
Figure 5.13.2-1: Initial condition
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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.
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5.13.3  Service FlowsWord‑p. 34
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.
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5.13.4  Post-conditions

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.

5.13.5  Existing features partly or fully covering the use case functionalityWord‑p. 35
Following are existing requirements specified in TS 22.261:
  • The 3GPP system shall support selection and reselection of relay UEs based on a combination of different criteria e.g.
    • the capabilities/capacity/coverage when using the relay UE,
    • the QoS that is achievable by selecting the relay UE,
    • the power consumption required by relay UE and remote UE,
    • the pre-paired relay UE,
    • the 3GPP or non-3GPP access the relay UE uses to connect to the network,
    • the 3GPP network the relay UE connects to (either directly or indirectly),
    • the overall optimization of the power consumption/performance of the 3GPP system, or
    • battery capabilities and battery lifetime of the relay UE and the remote UE.
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.
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5.13.6  Potential New Requirements needed to support the use case

Following new requirements can be derived from this use case:
[PR.5.13.6-1]
For traffic pertaining to a network slice offered via a relay node, 5G system shall use only radio resources (e.g. frequency band) allowed for the network slice.

6  Potential Consolidated Requirements

Following are consolidated potential requirements.
[CPR-001]
For a UE authorized to access multiple network slices of one operator which cannot be simultaneously used by the UE (e.g. due to radio frequency restrictions), the 5G system shall be able to support the UE to access the most suitable network slice in minimum time (e.g. based on the location of the UE, ongoing applications, UE capability, frequency configured for the network slice).
[CPR-002]
For a UE authorized to access to multiple network slices of one operator which cannot be simultaneously used by the UE (e.g. due to radio frequency restrictions), the 5G system shall minimize service interruption time when the UE changes the access from one network slice to another network slice. (e.g. based on changes of active applications).
[CPR-003]
5G system shall minimize signaling exchange and service interruption time for a network slice, e.g. when restrictions related to radio resources change (e.g., frequencies, RATs).
[CPR-004]
For a roaming UE activating a service/application requiring a network slice not offered by the serving network but available in the area from other network(s), the HPLMN shall be able to provide the UE with prioritization information of the VPLMNs with which the UE may register for the network slice.
[CPR-005]
In case a third party has requested provision of a network slice using specific radio resources for the network slice, the 5G system shall be able to generate charging information regarding the used radio resources e.g. used frequency bands.
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7  Conclusions and RecommendationsWord‑p. 36
This document analyses a number of use cases to enhance the support of network slice. The resulting potential requirements have been consolidated in clause 6.
It is recommended that the consolidated potential requirements identified in this TR are considered as the basis of normative requirements in order to better serve the communication services.

A  Consideration for different type of frequencyWord‑p. 37
Frequency band defined in 3GPP can be classified into FDD frequency and TDD frequency as shown in Table 5.2-1 of TS 38.101-1 and TS38.101-2 [6]. In case of TDD system, the same frequency is used for both UL and DL. However, in case of FDD system, UL frequency is different from DL frequency. Thus, when radio resource restriction scenario is discussed, care should be taken by considering these variations e.g. frequency used for both DL/ UL, UL only or DL only.
In addition, 5G system introduces further flexibility in using frequency band. For example, SUL (Supplementary UL) and SDL (Supplementary DL) are frequency band either defined only in DL or only in UL, as described in annex B of TS 38.300. This spectrum is used to assist other frequency band, e.g. when base frequency band lacks coverage in either DL or UL, then SUL or SDL can be used to replace the base frequency band. If the SUL and/or SDL band is restricted for a certain network slice, some UEs may experience reduced coverage for the network slice.
Aspects related to carrier aggregation also needs to be considered similarly, because it is used to support QoS requirement by using different combination of DL bands and UL bands, e.g. using three DL bands together with one UL bands to boost downlink data rate. If allowed network slices differs for different frequency bands, then operation of CA also needs to take this into account for a network slice.
DSS (Dynamic Spectrum Sharing) allows use of same frequency band for both NR and E-UTRA, to cater for various deployment scenario of operators. Thus, same frequency band is split in time to support both E-UTRA and NR. Thus, when there is active restriction for a RAT in using a frequency, consideration should be given in which case it is restricted and any potential impact on quality of service.
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$  Change historyWord‑p. 38

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