Femto Node Transmit Power Control for Macrocell Interference
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Solution Overview
Problem
Femto cells in wireless communication systems cause interference with macro cells due to ad-hoc deployment, leading to suboptimal RF coverage and communication performance, particularly in multi-resident apartments where unplanned installation results in interference between neighboring femto base stations.
Innovation Solution
Implement a method in femto nodes to monitor interference levels with macro cells, determine an optimal transmit power for user equipment to minimize interference, and adjust transmit power settings accordingly, using busy indicators and signal strength measurements to manage interference and maintain effective communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If femto base stations are deployed in an ad-hoc manner to supplement macro cell coverage, then indoor wireless coverage is improved, but interference with macro cells and other femto cells increases
Solution Approach 1:
The patent implements dynamic transmit power adjustment for user equipment communicating with femto cells. The system continuously monitors interference levels and adjusts the maximum allowed transmit power accordingly, transitioning from static power settings to adaptive power control that responds to real-time network conditions, thereby reducing interference while maintaining coverage.
Solution Approach 2:
The patent establishes a feedback mechanism where the femto base station monitors uplink interference at the macro cell and sends control signals to adjust user equipment transmit power. This closed-loop feedback system enables the network to automatically respond to interference conditions and optimize power settings without manual intervention.
2Reliability
If user equipment transmits at high power to maintain communication with femto cell, then communication reliability is improved, but interference to macro cell base station increases
Solution Approach 1:
The patent changes the power parameter dynamically by adjusting the maximum allowed transmit power of user equipment based on monitored interference conditions. Instead of using a fixed high power setting, the system varies the power parameter in response to network conditions, achieving a balance between maintaining communication reliability and reducing harmful interference to macro cells.
Data Source
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AI summary
Transmit power for a user equipment (UE) is set by a Home NodeB (HNB) in response to interference at a nearby macrocell. The HNB monitors an interference level to the macrocell from a UE communicating with the HNB. An acceptable transmit power for the UE is determined by the HNB in response to the interference level. A power change indicator is transmitted from the HNB to the UE to adjust the transmit power of the UE. In some cases, the interference may be estimated from a busy indicator from the macrocell and the HNB sends a modified version of the busy indicator to the UE to adjust the transmit power of the UE. In other cases, the HNB estimates a path loss for the UE based on received signal power from the macrocell and signals a transmit power change to the UE, if needed, based on the estimated path loss.