Femto Base Station Pilot Power Control for Quality Consistency
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Solution Overview
Problem
Indoor communication quality in femto base stations is inconsistent due to the placement of femto base stations and mobile stations, leading to variable reception of common pilot signals and increased interference, making it difficult to maintain appropriate communication quality.
Innovation Solution
A wireless communication system where a second base station measures the reception quality of a first pilot signal and adjusts its own transmission power to ensure that the lowest reception quality level among connected mobile stations reaches a predetermined target level, thereby maintaining consistent communication quality while minimizing transmission power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If femto base stations transmit common pilot signals with fixed transmission power, then the system is simple to operate, but communication quality becomes inconsistent due to variable placement and interference conditions
Solution Approach 1:
The femto base station measures the reception quality of common pilot signals from other base stations and uses this feedback information to autonomously adjust its own transmission power, creating a closed-loop control system that adapts to changing environmental conditions while maintaining consistent communication quality
Solution Approach 2:
The femto base station autonomously determines and adjusts its own transmission power without external control, using its own measurements of received pilot signal quality to self-regulate power levels according to the formula Ptx = Pmacro + Poffset, eliminating the need for complex external power management
2Reliability
If femto base stations autonomously set transmission power based on received power measurements, then communication quality improves, but interference to other cells increases
Solution Approach 1:
The transmission power parameter is dynamically adjusted based on the measured reception quality parameter, changing from a fixed value to a variable value that adapts to environmental conditions, thereby improving communication quality while controlling interference through measured feedback
3Reliability
If transmission power is increased to ensure coverage for all permitted mobile stations, then communication quality becomes consistent, but power consumption increases
Solution Approach 1:
The transmission power transitions from a static fixed value to a dynamic value that changes based on measured reception quality, allowing the system to use only the necessary power level required for each specific environmental condition rather than constantly operating at maximum power
Data Source
AI summary
To provide appropriate communication quality for a mobile station that is permitted to connect to a femto base station regardless of the place at which the femto base station is installed and the place at which the mobile station is used while reducing the transmission power of the femto base station as much as possible, a femto base station 4 measures the reception quality (e.g., received power or reception SIR) by receiving a common pilot signal from a macro base station 3, and sets the transmission power Ptx of a pilot signal to be transmitted by the femto base station itself based on the received power. Further, the femto base station 4 transmits a common pilot signal with a transmission power Ptx and communicates with a plurality of mobile stations 7-2 to 7-4 within a femtocell 6. Furthermore, the femto base station 4 receives a measurement result of the reception quality level of a common pilot signal transmitted from the femto base station 4 from the mobile stations 7-2 to 7-4, and adjusts the transmission power Ptx of a common pilot signal so that the lowest level among a plurality of reception quality levels gets closer to a predetermined target level.