Femtocell Interference Control via Conditional Transmitter Activation
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Solution Overview
Problem
In wireless communication systems with overlapping macro and femto cells, inter-cell interference occurs due to the installation of femto base stations within macro cells, leading to service quality degradation and increased business costs for service providers.
Innovation Solution
A method is introduced where a femto base station switches on its transmitter only when a registered mobile station enters its coverage area, using a femtocell driving control message transmitted at a predetermined power, and the macro base station notifies the mobile station of its entry into a home cell, thereby controlling interference between macro and femto cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If femto base stations are installed within macro cells to improve indoor signal environment, then service quality is improved, but inter-cell interference occurs between macro and femto cells
Solution Approach 1:
The femto base station dynamically switches its transmitter between on and off states based on whether a preregistered mobile station is detected in its coverage area. This dynamic operation allows the femto base station to provide service quality improvement when needed while avoiding continuous transmission that would cause inter-cell interference with macro cells and other femto base stations.
Solution Approach 2:
The system changes the transmission state parameter of the femto base station from continuous operation to conditional operation. When a mobile station enters the femtocell coverage area, the transmitter parameter switches from off to on state, and vice versa when the mobile station leaves, thereby controlling interference through parameter change.
2Adaptability or versatility
If femto base stations use omnidirectional antennas to provide coverage, then service coverage is improved, but signals from macro base stations and other femto base stations cause interference to mobile stations
Solution Approach 1:
Instead of continuous transmission, the femto base station employs periodic transmission by switching the transmitter on and off based on mobile station presence. This periodic action pattern allows the omnidirectional antenna to provide coverage when needed while minimizing interference to mobile stations during off periods.
Data Source
AI summary
A wireless communication system with femtocells and a method for mitigating inter-cell interference in the wireless communication system are provided. The interference control method includes notifying a mobile station of entry to a home cell, when the mobile station enters a macrocell including a femto base station with which the mobile station is registered, transmitting, by the mobile station, a femtocell driving control message to the femto base station at a predetermined transmission power, when the mobile station enters a femtocell of the femto base station, and switching on, by the femto base station, a transmitter, when the femtocell driving control message is received.