Inter-RAT Load Balance via Probability Threshold
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Solution Overview
Problem
Current inter-Radio Access Technology (RAT) load-balancing and congestion control methods are unfair to certain user groups and inefficient in managing primary RAT congestion, as they either group users unfairly or require frequent updates in priority thresholds, leading to suboptimal Quality of Service (QoS) and radio resource utilization.
Innovation Solution
A broadcast message is used by the secondary RAN to control idle reselection to the primary RAT, featuring a group-agnostic probability threshold for all users, enabling only those with random values exceeding the threshold to reselect, along with a retention timer to prevent repeated attempts, and an optional congestion indicator to prevent reselection when the primary RAT is congested.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If group-based user division is used for load balancing, then load distribution is achieved, but fairness among user groups deteriorates
Solution Approach 1:
The patent changes the parameter from fixed group-based control to dynamic probability threshold control. Each UE generates a random value and compares it with a broadcast probability threshold to determine reselection behavior. This parameter change eliminates the need for unfair group division while maintaining load distribution efficiency through probabilistic control.
2Reliability
If priority threshold updates are used for congestion control, then congestion management is achieved, but system complexity and update frequency requirements increase
Solution Approach 1:
The patent replaces the complex priority threshold parameter with a simpler probability threshold parameter. The probability threshold directly controls the proportion of UEs that will reselect to the primary RAT, eliminating the need for frequent updates and complex management while maintaining effective congestion control.
Solution Approach 2:
Each UE independently generates a random value and compares it with the broadcast probability threshold to determine its own reselection behavior. This self-service mechanism eliminates the need for complex network-side priority management and frequent updates, as each UE autonomously makes the reselection decision based on the probability threshold.
3Adaptability or versatility
If frequent reselection attempts are allowed, then user access flexibility is improved, but network congestion worsens
Solution Approach 1:
The patent introduces a retention timer that creates periodic action in the reselection process. After a UE fails the probability test or reselects to the primary RAT, it must wait for the retention timer to expire before attempting reselection again. This periodic restriction prevents continuous reselection attempts that would worsen congestion while still allowing flexible access when conditions improve.
Data Source
Figure 1~2
Figure 3A~3C
Figure 3B
AI summary
A system (24) and method (40, 54, 68, 77, 92) to perform load-balancing and congestion control between a primary Radio Access Technology (RAT) (27) and a secondary RAT (28). A broadcast message is sent to all User Equipments (UEs) (34) operating under the secondary RAT. If the primary RAT is congested, a congestion indicator in the broadcast message prevents the UEs from idle re-selecting or switching to the primary RAT. Even if the primary RAT is not congested, the broadcast message may stilt include other parameters such as one or more probability values, a group identifier for the UE groups, and a retention timer. The idle UEs in the secondary RAT that generate device-specific random values that are equal to or greater than the applicable probability threshold value(s) are allowed to reselect the primary RAT. If an idle UE fails this probability test, it may not be allowed to reselect the primary RAT again until the retention timer expires.