Inter-Frequency Handover for Femtocell Interference Prevention
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Solution Overview
Problem
Femtocell interference due to shared identification codes leads to handover failures between macrocell and femtocell base stations, causing frequency interference and degrading service quality in communication networks.
Innovation Solution
Implementing an inter-frequency handover method that selects an unshared frequency with lower load and higher quality, allowing user equipment to switch from a shared frequency used by macrocells to an unshared frequency not assigned to femtocells, thereby preventing frequency interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the same identification codes are allocated to multiple femtocell base stations to expand service coverage, then the service capacity of the macrocell is increased, but handover failures occur due to inability to distinguish target femtocell base stations
Solution Approach 1:
The patent introduces frequency information as an intermediary parameter to distinguish between femtocell base stations that share the same identification code. When handover is requested, the source base station selects a target femtocell base station by comparing frequency information in addition to identification codes, enabling unique identification of the target station even when identification codes are reused across multiple femtocells.
2Productivity
If multiple femtocells are installed within a single macrocell to distribute network load, then service capacity is increased, but frequency interference problems occur between femtocells
Solution Approach 1:
The patent applies local quality by assigning different frequency resources to different femtocell base stations within the same macrocell. Each femtocell operates on a specific frequency, creating localized frequency differentiation that prevents interference between co-located femtocells while maintaining their individual service capacities.
Solution Approach 2:
The patent changes the frequency parameter to resolve interference issues. By selecting target femtocell base stations based on frequency information and performing handover to frequencies with lower interference levels, the system dynamically adjusts frequency usage to eliminate harmful interference between femtocells.
3Device complexity
If identification codes are reused for multiple femtocell base stations due to shortage of codes, then device complexity is reduced, but handover procedure fails when target femtocell cannot be distinguished
Solution Approach 1:
The patent adds another dimension (frequency information) to the identification process. Instead of relying solely on identification codes, the system uses a combination of identification codes and frequency information to uniquely identify target femtocell base stations, effectively creating a two-dimensional identification space that resolves the ambiguity caused by code reuse.
Data Source
AI summary
Provided are apparatus and method for controlling handover to prevent femtocell interference. The apparatus may include an event receiving module, a handover determining module, and an inter-frequency processing module. The event receiving module may be configured to receive a control message from user equipment. The handover determining module may be configured to analyze the received control message and determine whether the control message includes a request of inter-cell handover from a first cell base station of the first cell to a second cell base station of one of the second cells. The inter-frequency processing module may be configured to perform inter-frequency handover using an unshared frequency when the handover determining module determines that the control message includes the request of inter-cell handover.