SCEF Buffer Handling for Non-IP Data Delivery in PSM Devices
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Solution Overview
Problem
The current mobile terminated Non-Internet Protocol (IP) Data Delivery (NIDD) procedure in 3GPP specifications does not efficiently handle power saving devices using Extended Discontinuous Reception (eDRX) and Power Saving Mode (PSM), leading to issues with data delivery due to devices being unreachable during low-power states.
Innovation Solution
A buffer handling mechanism is introduced between the Serving Gateway (S-GW) and Packet Data Network (PDN) Gateway, with added signaling to manage buffering when CIoT User Equipment devices are using PSM or eDRX, involving the Serving Network Inter-Working (IWK) Service Capability Exposure Function (SCEF) to avoid data loss and ensure efficient delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If UEs use eDRX or PSM to save energy by listening to radio only during short periods, then energy consumption is reduced, but data delivery reliability deteriorates because UEs are unreachable during sleep states
Solution Approach 1:
The network performs preliminary actions by buffering downlink data at the SCEF or MME before the UE becomes reachable. The system proactively stores data during the UE's sleep period and automatically forwards it when the UE wakes up, eliminating the need for the UE to continuously monitor the radio for data availability.
Solution Approach 2:
The SCEF or MME acts as an intermediary between the data network and the UE during sleep periods. The intermediary buffers data, manages the delivery timing, and ensures data is forwarded to the UE when it becomes reachable, resolving the unreliability issue without requiring the UE to stay awake.
2Speed
If the network continuously monitors UEs for data delivery, then data delivery speed is improved, but energy consumption increases because UEs must keep radio active
Solution Approach 1:
The network performs preliminary buffering actions during the UE's sleep period, so data is ready for immediate delivery when the UE wakes up. This maintains fast delivery speed without requiring continuous UE radio monitoring, as the buffering work is done in advance by the network.
Solution Approach 2:
The system uses periodic DRX cycles where the UE alternates between sleep and wake states. Data delivery is synchronized with these periodic wake periods, allowing the UE to conserve energy during sleep while ensuring data is delivered during scheduled wake times without requiring continuous radio activity.
3Reliability
If data is buffered in MME for PSM/eDRX devices, then data loss is prevented, but system complexity increases due to additional buffering management signaling
Solution Approach 1:
The MME and SCEF are designed to perform multiple functions: they act as both mobility management entities and data buffering points for PSM/eDRX devices. This multi-functionality allows data buffering to be integrated into existing network elements without adding separate dedicated buffering infrastructure, thereby limiting the increase in system complexity.
Solution Approach 2:
The network elements (SCEF/MME) automatically manage data buffering and delivery timing based on UE reachability information. The system self-services by autonomously determining when to buffer data, when to forward it, and how to handle delivery failures without requiring complex external coordination or manual intervention.
Data Source
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AI summary
A method in a core network node (22, 36) and a core network node for delivery of non-IP data comprising: receiving (103) a NIDD submit request comprising non-IP data and an identifier of a wireless device (18) to which the non-IP data is to be delivered; upon determining that the wireless device (18) is not reachable, sending (104) a NIDD submit response that indicates that the non-IP data was not delivered to the wireless device (18); and upon determining that the wireless device (18) is reachable, sending (106) a NIDD submit indication indicating that the wireless device (18) is reachable.