Cell Reselection Control for IoT Load Balancing
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Solution Overview
Problem
In mobile communication systems, especially for machine type communication (MTC) and Internet of Things (IoT) services, the enhanced coverage function increases cell load, leading to potential communication failures due to access restrictions when radio terminals in RRC idle mode cannot select a serving cell, causing load imbalances and interference issues.
Innovation Solution
A cell reselection control method where a base station transmits reselection instructions to radio terminals in enhanced coverage to switch to neighboring cells, allowing intra-frequency reselection even when access restrictions are set, thereby reducing load on the original cell and minimizing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If access restrictions are set for the cell to reduce load, then cell load is reduced, but radio terminals cannot select the cell as serving cell causing communication failure
Solution Approach 1:
The cell coverage is segmented into first coverage (normal coverage) and second coverage (enhanced coverage). Different access restriction policies are applied to different segments: access restrictions are enforced for terminals in first coverage, while terminals in second coverage are allowed to perform intra-frequency reselection. This segmentation resolves the contradiction by applying differentiated control strategies to different terminal groups based on their coverage requirements.
Solution Approach 2:
Different reselection control behaviors are applied to different local regions (coverage areas). Terminals in enhanced coverage area (second coverage) are granted special permission to perform intra-frequency reselection despite access restrictions, while terminals in normal coverage area (first coverage) follow standard access restriction rules. This local quality differentiation allows the system to maintain communication reliability for edge terminals while still managing overall cell load.
2Area of stationary object
If coverage enhancement function is applied to increase coverage area, then coverage area is enhanced, but cell load increases due to repetition
Solution Approach 1:
The system dynamically adjusts reselection behavior based on terminal location and coverage requirements. Terminals in enhanced coverage area can dynamically perform intra-frequency reselection to neighboring cells when needed, allowing the system to adaptively manage load distribution while maintaining coverage enhancement benefits. This dynamic control enables the system to respond to changing traffic patterns and load conditions.
3Reliability
If many radio terminals are in RRC idle mode in enhanced coverage, then coverage is improved, but load on cell increases due to paging transmission and reception
Solution Approach 1:
The system segments terminal management by coverage type, applying different control mechanisms to terminals in enhanced coverage versus normal coverage. By allowing intra-frequency reselection for enhanced coverage terminals, the system distributes these terminals across multiple cells, reducing the concentration of idle terminals in any single cell and thereby reducing paging-related load on individual cells.
Data Source
AI summary
A cell reselection control method according to an embodiment comprises transmitting, by a base station configured to manage a cell having a first coverage and a second coverage as a portion enhanced more than the first coverage, to a radio terminal under the cell, a reselection instruction that instructs to reselect a neighboring cell different from the cell, and reselecting, by the radio terminal, the neighboring cell according to the reselection instruction when the radio terminal is in the second coverage.