Serving Gateway Downlink Buffering for Idle UE Reachability
Solution Overview
Problem
Current packet mobile communication networks face inefficiencies in supporting mobile-terminated communications for devices in idle mode using power saving mechanisms like Power Saving Mode (PSM) or Extended Discontinuous Reception (DRX), leading to increased network load and difficulty in reaching devices due to downlink packet retransmissions and inefficient SMS-based triggering.
Innovation Solution
Implementing a method where Downlink packets are buffered in the Serving Gateway for a specified duration when a UE is in PSM or extended DRX, allowing the network to store and forward packets efficiently upon the UE's next active period, and using modified procedures for Mobile Terminated SMS and Location Requests to ensure timely delivery and location reporting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If power saving mechanisms (PSM or extended DRX) are used to reduce device power consumption, then device power consumption is reduced, but device reachability deteriorates and network load increases due to packet retransmissions
Solution Approach 1:
The network performs preliminary actions by buffering downlink packets at the Serving Gateway before the device becomes unreachable, and proactively notifies the device of upcoming wake-up times. This allows packets to be ready for immediate delivery when the device wakes, eliminating retransmissions and improving reachability while maintaining power savings.
Solution Approach 2:
The Serving Gateway acts as an intermediary between the packet core network and the power-saving device. It buffers downlink packets, manages the packet forwarding to the device at appropriate times, and coordinates with the MME/SGSN to notify the device of wake-up times, thereby solving the reachability problem without requiring the device to remain continuously connected.
2Productivity
If downlink packets are immediately discarded when UE is in power saving mode, then network load is reduced, but packet delivery reliability deteriorates requiring retransmissions
Solution Approach 1:
The network performs preliminary buffering of downlink packets at the Serving Gateway before the device becomes unreachable, and proactively notifies the device of upcoming wake-up times. This allows packets to be ready for immediate delivery when the device wakes, eliminating retransmissions and improving reachability while maintaining power savings.
Solution Approach 2:
The system implements feedback mechanisms where the MME/SGSN notifies the UE of upcoming wake-up times, and the UE confirms its availability. This feedback loop ensures that buffered packets are delivered at optimal times, balancing network load reduction with reliable packet delivery.
3Ease of operation
If network triggers service request for mobile terminated communication, then mobile terminated communication is supported, but network load increases and power consumption increases
Solution Approach 1:
The network performs preliminary buffering of downlink packets at the Serving Gateway before the device becomes unreachable, and proactively notifies the device of upcoming wake-up times. This allows packets to be ready for immediate delivery when the device wakes, eliminating retransmissions and improving reachability while maintaining power savings.
Solution Approach 2:
The system maintains continuous packet buffering capability at the Serving Gateway throughout the device's power-saving cycle, ensuring that downlink data is always available for immediate forwarding when the device becomes reachable, thus supporting mobile-terminated communication continuously without interrupting the device's power-saving operation.
Data Source
AI summary
In an embodiment, there is provided a method for support of mobile-terminated communication in an Evolved Packet System, towards a User Equipment UE in idle mode using a power saving mechanism whereby the UE is transiently not reachable, the method includes allowing one or more Downlink DL packets received for the UE to be buffered in a Serving Gateway SGW, upon request, for up to a duration referred to as DL buffering duration.