SCEF MME Connection Establishment for Non-IP Data Delivery
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Solution Overview
Problem
In the Cellular Internet of Things (CIoT) Evolved Packet System (EPS), there is a challenge in delivering non-IP data to User Equipment (UE) without an existing connection between the Service Capability Exposure Function (SCEF) and the Mobility Management Entity (MME), leading to service disruptions and increased pending UE contexts or connections.
Innovation Solution
A method is introduced where the SCEF receives a message for non-IP data delivery, retrieves MME information, and sends a Connection-Management-Request (CMR) message to establish a connection with the MME, even if no connection exists, allowing for non-IP data delivery and re-establishment of connections if the MME loses connectivity, ensuring service continuity and reducing pending UE contexts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the SCEF waits for an existing connection with the MME before delivering non-IP data, then connection stability is maintained, but service continuity deteriorates when connections are lost
Solution Approach 1:
The SCEF performs preliminary actions by proactively establishing connections with MMEs before data delivery is required. When downlink data arrives at the SCEF, it initiates connection establishment procedures in advance, retrieving MME information from HSS and sending Connection-Management-Request messages to ensure connections are ready before needed, thereby maintaining service continuity even if previous connections were lost.
2Reliability
If the SCEF actively establishes connections with MMEs, then service continuity is improved, but the number of pending UE contexts increases
Solution Approach 1:
The connection establishment mechanism is made dynamic rather than static. The SCEF establishes connections on-demand based on actual data delivery requirements, and maintains connections only as long as necessary. This dynamic approach allows the system to adapt connection states to current needs, reducing the accumulation of pending UE contexts while ensuring service continuity when connections are actively established.
3Speed
If the SCEF retrieves MME information frequently to establish connections, then connection establishment speed is improved, but signaling overhead increases
Solution Approach 1:
The SCEF performs preliminary retrieval of MME information from HSS when downlink data arrives, before actual connection establishment is needed. This preliminary action prepares the necessary routing information in advance, so when connection establishment is required, the SCEF already has the MME details needed to quickly initiate the Connection-Management-Request, thereby reducing the overall time and signaling overhead for connection establishment.
Data Source
AI summary
A method in a SCEF is provided. The method comprises receiving a message indicating that non-IP data is to be delivered to a UE. The method further comprises retrieving information associated with a MME serving the UE. The method further comprises transmitting, to the MME, a message triggering establishment of a connection between the SCEF and the MME for delivering the non-IP data. Other devices and methods for connection establishment between MME and SCEF are also provided.