Mobility Control Method for Inter-Cell Interference Mitigation
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Solution Overview
Problem
In cellular wireless communication systems using OFDMA, inter-cell interference is significant, particularly at cell edges, leading to reduced channel capacity and increased load on base stations, making it difficult to maintain communication quality and balance load distribution between cells of varying sizes.
Innovation Solution
A mobility control method that utilizes interference and load information to facilitate handovers from cells with high terminal loads to those with low loads, adjusting handover criteria based on cell size and load balance to minimize interference and optimize channel capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If transmit power of all wireless stations is lowered to minimum required level to reduce inter-cell interference, then interference between neighboring cells is reduced, but coverage area shrinks and communication speed decreases
Solution Approach 1:
The patent applies local quality by differentiating power control strategies between cell-edge terminals and non-cell-edge terminals. Cell-edge terminals receive enhanced power control adjustments to maintain coverage, while other terminals use standard power control. This localized differentiation allows interference reduction without sacrificing overall coverage area.
Solution Approach 2:
The patent changes the power control parameter dynamically based on terminal location and cell load conditions. By adjusting the power control adjustment amount as a variable parameter rather than a fixed value, the system can reduce interference when possible while maintaining coverage requirements, resolving the contradiction between interference reduction and coverage maintenance.
2Object-affected harmful factors
If transmit power of all wireless stations is lowered to minimum required level to reduce inter-cell interference, then interference between neighboring cells is reduced, but communication speed decreases
Solution Approach 1:
The patent applies local quality by differentiating power control strategies between cell-edge terminals and non-cell-edge terminals. Cell-edge terminals receive enhanced power control adjustments to maintain communication quality, while other terminals use standard power control. This localized differentiation allows interference reduction without sacrificing overall communication speed.
Solution Approach 2:
The patent changes the power control parameter dynamically based on terminal location and cell load conditions. By adjusting the power control adjustment amount as a variable parameter rather than a fixed value, the system can reduce interference when possible while maintaining communication speed through adaptive parameter adjustment.
3Area of stationary object
If cell size of base station is increased to cover larger area, then coverage area is expanded, but interference to neighboring cells increases
Solution Approach 1:
The patent applies dynamics by making the power control adjustment amount variable rather than fixed. The adjustment amount changes dynamically based on real-time conditions including terminal location relative to cell edge and base station load status. This dynamic adjustment allows large cells to adapt their transmit power to minimize interference while maintaining coverage.
Solution Approach 2:
The patent implements feedback mechanisms where the base station receives power information from terminals and adjusts power control parameters accordingly. This feedback loop enables the system to respond to changing conditions and balance coverage requirements against interference constraints, allowing large cells to operate efficiently without excessive interference.
4Productivity
If handover criteria is adjusted to balance load between cells, then load distribution is optimized, but handover control complexity increases
Solution Approach 1:
The patent changes handover criteria parameters dynamically based on base station load conditions. Rather than using fixed handover thresholds, the system adjusts power control adjustment amounts and handover parameters according to real-time load status. This parameter adaptation enables load balancing while keeping the control mechanism relatively simple by building upon existing handover frameworks.
Data Source
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AI summary
Interference applied to neighbor cells during terminal handovers can be reduced in wireless communication systems containing base stations 201 having different cell sizes. A serving cell makes handover judgment criteria easier based on pre-acquired cell size information on its own cell and cell size information of neighbor cells in order to facilitate terminal handovers from a base station 201 with a large cell size to a base station 201 with a small cell size. The serving cell finds evaluation function values based on the propagation state (e.g. reference signal received power) between the terminal 203 and target cell, and the interference and load information exchanged between the base stations 201, and selects the terminal 203 for handover by comparing the evaluation function value with the handover criteria value. The system selects a target cell having a good effect in lowering interference such as a cell with large reference signal received power acquired from a terminal 203, to serve as the handover destination.