ANDSF Rule Validity via UE Historical Trajectory
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Solution Overview
Problem
Existing access network selection methods, such as those using ANDSF rules, lead to unnecessary handovers between cellular and WLAN networks for users in motion, causing signaling overload and service interruptions due to frequent switches between networks.
Innovation Solution
Implementing an ANDSF server and client system that defines ANDSF rules with validity conditions including historical trajectory and location areas, allowing the UE to selectively switch between networks based on past location patterns, thereby preventing unnecessary handovers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ANDSF rules prioritize WLAN over cellular network, then WLAN connectivity is improved for stationary users, but unnecessary successive handovers occur for moving users
Solution Approach 1:
The patent applies dynamics by making the ANDSF rule validity conditional on the UE's movement state. The system dynamically evaluates whether the UE is stationary or moving before applying the WLAN priority rule. When the UE is detected to be moving, the rule becomes invalid, preventing unnecessary handovers. When the UE is stationary, the rule becomes valid, ensuring reliable WLAN connectivity. This dynamic adaptation resolves the contradiction between improving WLAN reliability and preventing harmful successive handovers.
2Adaptability or versatility
If ANDSF rules enable frequent handovers to WLAN, then network selection adaptability is improved, but signaling load and battery consumption increase
Solution Approach 1:
The patent implements feedback by continuously monitoring the UE's movement state and using this information to control the application of ANDSF rules. The system receives feedback about UE mobility from the network or UE itself, evaluates this feedback against the validity conditions, and adjusts rule application accordingly. This feedback mechanism maintains network selection adaptability while preventing energy-wasting successive handovers by only allowing WLAN switching when appropriate.
3Ease of operation
If ANDSF rules are applied without validity conditions, then ease of operation is improved, but service interruption occurs due to successive handovers
Solution Approach 1:
The patent applies preliminary action by pre-defining validity conditions in the ANDSF rules that specify when each rule should be applied or not applied. These validity conditions are established in advance based on UE movement state, location information, or other predictive criteria. When the validity conditions are not met (e.g., UE is moving), the rule is automatically invalid, preventing service interruptions from successive handovers. This preliminary configuration maintains ease of operation while ensuring service continuity.
Data Source
AI summary
A method is provided that includes defining at an ANDSF server an ANDSF rule that includes a validity condition to be fulfilled. The validity condition includes a validity location area and a validity trajectory towards the validity location area, and the validity trajectory includes a list with one or more previous location areas. The method also includes transmitting the ANDSF rule from the ANDSF server to an ANDSF client of the UE; tracking, at the ANDSF client, a historical trajectory for the UE by storing a list with one or more successive location areas where the UE has been located; and upon matching a current location of the UE with the validity location area, and the tracked historical trajectory for the UE with the validity trajectory, determining that the validity condition is fulfilled and applying the ANDSF rule at the ANDSF client.