Femto Base Station Radio Resource Control for Interference Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Femto base stations located in close proximity to each other within a building experience significant interference issues due to shared frequency bands, leading to potential degradation of downlink and uplink signal quality for registered mobile stations.
Innovation Solution
A radio resource control method that records and analyzes connection request histories from unregistered mobile stations to adjust radio resources, such as transmission power, and frequency bands, to minimize interference between registered and unregistered stations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If femto base stations transmit common pilot signals using the same frequency band to enable communication with registered mobile stations, then communication functionality is provided, but interference occurs between adjacent femto base stations causing degradation of signal quality
Solution Approach 1:
The patent applies local quality by allowing each femto base station to independently determine its transmission power based on its local environment (received power from macro base station and connection request history). This enables each station to adapt its signal characteristics to its specific location, reducing interference with neighboring stations while maintaining adequate coverage for registered mobile stations.
Solution Approach 2:
The patent changes the transmission power parameter dynamically based on the connection request frequency from unregistered mobile stations. By adjusting this parameter according to local conditions (using the formula Ptx = Pmacro + Poffset - α·F), the system optimizes the balance between providing communication functionality and minimizing interference to adjacent cells.
2Device complexity
If transmission power of common pilot signal is set to fixed value to simplify control, then system complexity is reduced, but interference cannot be suppressed between adjacent femto base stations
Solution Approach 1:
The patent implements self-service by enabling each femto base station to autonomously determine its transmission power without requiring complex centralized control. Each station independently measures the received power from macro base stations, counts connection requests from unregistered mobile stations, and calculates its own transmission power using a predefined formula, thereby simplifying overall system control while effectively suppressing interference.
3Object-affected harmful factors
If femto base station autonomously sets transmission power to reduce interference, then interference suppression capability is improved, but device complexity increases due to power control mechanisms
Solution Approach 1:
The patent employs feedback mechanisms by using the connection request frequency from unregistered mobile stations as an indicator of interference conditions. This feedback information, combined with measured received power from macro base stations, drives the autonomous transmission power adjustment, providing effective interference suppression through a relatively simple control loop that monitors and responds to actual interference conditions.
Data Source
AI summary
To effectively suppress interference on other radio stations located in the vicinity, when the radio station performs radio communication with a registered radio station. A femto base station 1 stores a history of connection requests issued by an unregistered radio station that is not pre-registered in the femto base station 1. Then, the femto base station 1 determines the need of a adjustment of a radio resource used in communication with a registered radio station that is pre-registered in the femto base station 1 itself by using connection request frequencies each for one of unregistered radio stations obtained from the connection request history as an index.