Femtocell Interference Mitigation via Dynamic Power Control
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Solution Overview
Problem
Femtocell base stations experience interference from non-CSG mobile stations, leading to communication disruptions, and existing solutions are incomplete in verifying the source of interference and mitigating it effectively.
Innovation Solution
The femtocell base station triggers non-CSG mobile stations to report interference information, performs checks to confirm if it is the source of interference, and implements measures like beamforming and power control to reduce interference, ensuring network entry only for legal users and mitigating interference through self-correction or coordination with other base stations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If femtocell base station transmit power is increased to ensure good signal strengths for subscribers, then signal quality for CSG members is improved, but interference to non-CSG mobile stations and other base stations increases
Solution Approach 1:
The femtocell base station applies different transmit power levels to different user groups: high power for CSG members to ensure good signal quality, and low or zero power for non-CSG mobile stations to minimize interference. This localized quality adjustment resolves the contradiction by tailoring the signal strength to the specific user category.
Solution Approach 2:
The transmit power of the femtocell base station is made dynamic rather than static. The system adjusts power levels in real-time based on the presence and status of mobile stations. When non-CSG mobile stations are detected or interference is reported, the femtocell dynamically reduces or mutes its transmit power, thereby resolving the contradiction between maintaining service quality and avoiding interference.
2Reliability
If femtocell base station uses CSG-Closed access to protect network resources, then security and resource control are improved, but interference to non-CSG mobile stations in coverage area increases
Solution Approach 1:
The femtocell base station performs preliminary actions by proactively muting or reducing its transmit power when non-CSG mobile stations are detected in its coverage area, before severe interference occurs. This preliminary action prevents the harmful effect while maintaining CSG resource control, as the power adjustment is triggered by detection rather than requiring full CSG authentication.
Solution Approach 2:
The system implements feedback mechanisms where non-CSG mobile stations can report experienced interference to the femtocell base station. The femtocell uses this feedback information to adjust its transmit power accordingly, creating a closed-loop control system that resolves the contradiction between CSG security and interference mitigation to non-CSG users.
3Object-affected harmful factors
If femtocell base station reduces transmit power to avoid interference, then interference to other base stations is reduced, but signal strength for subscribers decreases
Solution Approach 1:
The femtocell base station applies different transmit power levels to different spatial directions and user groups. It maintains high transmit power toward CSG members who need strong signal coverage, while simultaneously reducing or muting power in directions where non-CSG mobile stations or other base stations are located. This localized quality adjustment resolves the contradiction by directing high power only where needed.
Data Source
AI summary
A method for supporting wireless connectivity of a mobile station to a cellular network, wherein the mobile station is located within the coverage area of a femtocell base station of which it is a non-CSG mobile station, and wherein the mobile station experiences interference which it indicates to the femtocell base station, is characterized in that the femtocell base station, upon receiving the experienced interference indication from the non-CSG mobile station, triggers the non-CSG mobile station to report interference related information, wherein, based on the interference related information, the femtocell base station performs a first check whether it is originator of the interference experienced by the non-CSG mobile station. Furthermore, a corresponding femtocell base station for supporting wireless connectivity of a mobile station to a cellular network is disclosed.