Back-off Mechanism for Trusted WLAN Access Overload Control
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Solution Overview
Problem
Mobile communication networks face performance degradation in overload situations due to high signaling loads, particularly in Core Network entities, with no well-defined UE behavior for handling network overload in Trusted WLAN Access to EPC, especially in Single Connection Mode (SCM) and Transparent Single Connection Mode (TSCM), leading to increased signaling load and network congestion.
Innovation Solution
Implementing a back-off mechanism where the Trusted WLAN Access Network (TWAN) and AAA Server communicate a congestion cause and back-off time to the User Equipment (UE), causing the UE to refrain from new requests during the back-off period, thereby reducing signaling load and alleviating network congestion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE continuously retries requests during network congestion, then the UE attempts to maintain service connectivity, but the signaling load increases and network performance degrades
Solution Approach 1:
The patent applies preliminary anti-action by having the network proactively send a back-off indicator to the UE before the UE can generate excessive retry signaling. This preliminary signal prevents the harmful retry behavior before it occurs, reducing signaling load while maintaining connectivity reliability through controlled reattempt timing
Solution Approach 2:
The patent implements feedback by establishing a closed-loop mechanism where the network monitors congestion conditions and sends back-off indicators to UEs, which then adjust their retry behavior accordingly. This feedback loop enables dynamic adaptation of UE retry timing based on actual network conditions, balancing connectivity maintenance with signaling load reduction
2Object-generated harmful factors
If the network rejects requests during congestion without providing back-off information, then the signaling load is reduced, but the UE cannot determine when to retry and service continuity is impaired
Solution Approach 1:
The patent applies preliminary action by pre-calculating and providing the back-off timer value to the UE along with the rejection message. This allows the UE to immediately determine when to retry without generating additional probing signaling, thus reducing signaling load while ensuring service continuity through predictable retry timing
Solution Approach 2:
The patent implements self-service by enabling the UE to autonomously manage its retry behavior using the back-off indicator received from the network. The UE independently determines when to retry based on the provided timing information, eliminating the need for continuous network intervention and reducing signaling load while maintaining reliable service recovery
3Speed
If the UE implements aggressive retry behavior to overcome temporary congestion, then service recovery is faster, but network overload worsens and system stability decreases
Solution Approach 1:
The patent applies dynamics by making the UE retry behavior adaptive rather than static. The back-off indicator dynamically adjusts the retry timing based on current network congestion conditions, allowing faster recovery when appropriate while preventing instability during severe overload. This dynamic control balances service recovery speed with network stability
Solution Approach 2:
The patent implements parameter changes by modifying the retry timing parameter based on network conditions. The back-off indicator changes the retry delay parameter dynamically, enabling the system to optimize between fast recovery and stability by adjusting this key parameter according to congestion severity and duration
Data Source
AI summary
In an embodiment, a method is provided for overload control for Trusted WLAN access to EPC, comprising:when rejecting a request for an UE in single connection mode (SCM) for an authenticated and authorized user, the network signalling a back-off time to the UE for the requested APN when congestion control is active for the APN,upon reception of the back-off time, the UE not initiating new request for the congested APN, for the duration of the back-off time.