PGW Downlink Data Buffering for SGW Reselection in Wireless Networks
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Solution Overview
Problem
Wireless communication systems face inefficiencies in handling frequent changes of the Serving Gateway (SGW) due to the need for reselection and data forwarding when user equipment (UE) moves between different SGW service areas, particularly in scenarios where the control plane and user plane are separated.
Innovation Solution
A method and apparatus for a Packet Data Network Gateway (PGW) that buffers downlink data when not all tracking areas belong to the same SGW service area, allowing for efficient data transmission to the correct SGW as the UE moves, and performs session modifications to ensure seamless data delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If downlink data is transmitted without buffering when SGW service area coverage is uncertain, then data transmission speed is improved, but data delivery reliability deteriorates due to frequent SGW reselection
Solution Approach 1:
The PGW performs preliminary buffering of downlink data before determining the correct SGW destination. This advance preparation ensures that data is ready for immediate forwarding once the correct SGW is identified, resolving the contradiction by prioritizing reliable delivery preparation over immediate transmission speed.
Solution Approach 2:
The buffering function acts as an intermediary between data reception and data forwarding. By introducing this intermediate storage mechanism, the system can reliably capture incoming data while determining the appropriate SGW route, thus ensuring both reliability and eventual efficient delivery.
2Reliability
If data is buffered at PGW for all SGW reselection scenarios, then data delivery reliability is improved, but network complexity increases due to frequent buffering operations
Solution Approach 1:
The PGW applies buffering selectively based on local conditions - specifically when the TAI list indicates coverage across multiple SGW service areas. This localized application of buffering only where needed reduces unnecessary buffering operations and associated complexity while maintaining reliability where required.
Solution Approach 2:
The system changes the buffering parameter from a constant state (always buffer) to a conditional state (buffer only when TAI list spans multiple SGW areas). This parameter change optimizes the balance between reliability and complexity by adapting buffering behavior to specific network conditions.
3Reliability
If frequent data reforwarding is performed during SGW reselection, then data delivery completeness is improved, but network resource utilization deteriorates
Solution Approach 1:
Data is buffered in advance at the PGW before SGW reselection occurs, eliminating the need for frequent reforwarding operations. This preliminary buffering ensures data is ready for single-step forwarding to the new SGW, improving completeness while conserving network resources by avoiding repeated transmission cycles.
Data Source
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AI summary
One embodiment of the present invention relates to a method by which a packet data network gateway (PGW) processes data for an UE in a wireless communication system, the method comprising the steps of: receiving a tracking area identifier (TAI) list from a mobility management entity (MME); and receiving downlink data for the UE from a network, wherein the PGW buffers the downlink data when all of the tracking areas (TAs), which belong to the TAI list, are not included in the same serving gateway (SGW) service region.