Mobility Control Method for Heterogeneous Mobile Networks
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Solution Overview
Problem
In heterogeneous mobile communication networks with macro and small cells, the frequent creation of location registration signaling occurs due to the short duration of mobile station stays in small cells, especially when mobile stations move at high speeds, leading to increased signaling load and potential service quality degradation.
Innovation Solution
A mobility control method that sets different mobility determination times for individual neighbor cells or cell types based on their size, using extended cell reselection timers and speed-dependent scaling factors to delay location registration in small cells, thereby reducing unnecessary location registration and handover signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If small cells are deployed to provide coverage compensation and capacity increase, then coverage and capacity are improved, but the probability of radio wave interference increases and communication quality degrades
Solution Approach 1:
The network is segmented into macro cells and small cells with different functions. Macro cells provide broad coverage while small cells provide capacity enhancement in specific areas. This segmentation allows the system to achieve both coverage compensation and capacity increase while managing interference through functional differentiation.
Solution Approach 2:
Different cells are assigned different qualities and roles based on their characteristics. Small cells are deployed specifically in areas requiring capacity enhancement or coverage compensation, while macro cells cover broader areas. This local quality differentiation optimizes the network performance by placing the right type of cell in the right location.
2Measurement precision
If mobile stations frequently reselect to small cells during high-speed movement, then location registration accuracy is improved, but signaling load increases and service quality degrades
Solution Approach 1:
The cell reselection parameters are made dynamic and speed-dependent. The determination time for cell reselection is adjusted based on the mobile station's speed, with longer determination times for high-speed movements. This dynamic adjustment prevents frequent reselections during high-speed movement, reducing signaling load while maintaining adequate location registration accuracy.
Solution Approach 2:
The patent changes the parameter of determination time for cell reselection based on movement speed. By extending the determination time for high-speed mobile stations, the system reduces the frequency of cell reselection decisions, thereby reducing signaling load while still providing timely location updates when appropriate.
3Quantity of substance
If cell reselection determination time is extended to reduce reselection frequency, then signaling load is reduced, but mobility response time increases
Solution Approach 1:
The determination time is made dynamic rather than fixed. It is extended for high-speed mobile stations to reduce signaling load, but kept shorter for low-speed stations to maintain fast mobility response. This dynamic adjustment resolves the contradiction by adapting the determination time to the specific mobility scenario.
Solution Approach 2:
The patent introduces speed-dependent scaling factors that change the determination time parameter based on mobile station speed. This parameter change allows the system to optimize between signaling load reduction and mobility response time by adjusting the determination time according to the actual mobility conditions.
Data Source
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AI summary
A mobility control method and device that can suppress an increase of location registration signaling are provided. In a mobile communication network including cells (21 a, 21 b) of multiple types differing in cell size, mobility determination times (T_reselection) are determined for individual neighbor cells (22a-29d) or individual neighbor cell types (Operation 303), and mobility control is performed by determining whether or not a predetermined mobility criterion remains satisfied during the mobility determination time set for a neighbor cell (Operations 304-306).