This use case illustrates the realization of a S&F service between a UE with satellite access and an Application Server for a delay-tolerant/non-real-time IoT NTN service in the case of a Mobile Originated message. A description of store and forward operation is provided in Annex A. Company TrackingInc offers a service of remote monitoring of fields and deploys and tracks many battery-powered IoT type UEs across the globe. All the IoT remote monitoring UEs deployed include a 5G communication with satellite access. Some of the UEs are deployed in a remote area where there is no mobile coverage by MNO and only satellite is possible. For the satellite access, TrackingInc uses the service of IoTSAT for the 5G IoT connectivity by satellite and IoTSAT uses a LEO constellation which supports S&F operation mode. All IoT remote monitoring UEs regularly send information related to the area they are monitoring to the application server of TrackingInc and sometimes receive new parameters from the application server. In most of the cases, the messages exchanged are delay-tolerant/non-real-time IoT.

In the present use case, the IoT remote monitoring UE is in a remote area with no ground stations available for feeder link connectivity and the IoT remote monitoring UE is aware that IoTSAT constellation operates in S&F mode.

The IoT remote monitoring UE needs to send a message to the TrackingInc application server. The UE waits for satellite network coverage and sends its message when the satellite passes by. The IoT remote monitoring UE and the satellite providing coverage interact over the service link, allowing the UE to transfer the message to the satellite, which has no connectivity to the ground segment. And consequently, the satellite has to store locally the received message. At this point:

• Limitations to the size/amount of data that can be sent from the UE could be enforced.
• Forwarding priority for the stored data to the ground station and data retention period for the exchanged data could be established.
• Acknowledgement of the received data by the satellite could be issued.

At a later time, the satellite with the stored message establishes connectivity with the ground network via a feeder link and relays/forwards/downloads the message to the ground network. All accumulated and stored MO messages are delivered to the ground once the feeder link is available, at the same time, all accumulated and stored relevant MT messages are also delivered to the satellite via the same feeder link, which will impact the performance of the feeder link, 5GC, and satellite significantly. The relevant performance optimization method will be taken into consideration accordingly. The ground network, based on established connectivity configuration and routing, delivers message to the TrackingInc application server.

The message generated by the IoT remote monitoring UE has been either delivered successfully to the TrackingInc application server without relying on a continuous end-to-end network connectivity path between them or, in case the data retention period has been exceeded, the message has been discarded.

Clause 6.3.2.3 of TS 22.261 on satellite access includes the following requirements: However, it is not sufficient in regards of S&F operation especially for the delivery of delay-tolerant/non-real-time IoT NTN services with NGSO satellites.

[PR 5.1.6-001] [PR 5.1.6-002] [PR 5.1.6-003] [PR 5.1.6-004] [PR 5.1.6-005] [PR 5.1.6-006] [PR 5.1.6-007] [PR.5.1.6-008] [PR.5.1.6-009] [PR.5.1.6-010]