Uplink Power Control via Offset Values in LTE Base Stations
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Solution Overview
Problem
In next-generation mobile communication systems like E-UTRA and LTE, the conventional closed loop Transmitter Power Control method is challenging due to fluctuating transmission signal power and the need for wide bandwidth reference signals for channel quality measurement, making it difficult to maintain stable transmission power levels for uplink reference, control, and data signals.
Innovation Solution
A base station apparatus that receives uplink reference signals, provides transmission power control data, and derives offset power values to adjust the transmission power of uplink control and data signals, ensuring appropriate power levels by reporting these values to user equipment at a cycle longer than the predetermined cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wide bandwidth reference signals are transmitted for channel quality measurement, then channel quality measurement accuracy is improved, but transmission power stability deteriorates
Solution Approach 1:
The patent segments the uplink signals into three distinct types (reference signals, control signals, and data signals) with different power control mechanisms. Reference signals are transmitted at fixed power levels to ensure stable channel quality measurement, while control and data signals use dynamic power control based on offset values. This segmentation resolves the contradiction by isolating the measurement function from power fluctuations.
Solution Approach 2:
The patent applies different power control strategies to different signal types based on their specific requirements. Reference signals use fixed power for measurement stability, while control and data signals use dynamic offset-based power control. This local differentiation allows each signal type to optimize its performance characteristics without compromising others.
2Productivity
If transmission power is dynamically adjusted for uplink control and data signals, then transmission efficiency is improved, but power control complexity increases
Solution Approach 1:
The patent changes the power control parameter from direct power adjustment to offset value adjustment. The base station derives and signals offset values (first offset for control signals, second offset for data signals) relative to a reference power level. This parameter transformation simplifies the control mechanism while maintaining dynamic power adjustment capability, reducing complexity compared to direct power control.
Solution Approach 2:
The patent introduces offset values as an intermediary parameter between the base station's power control decisions and the actual transmission power. Instead of directly controlling absolute power levels, the system uses relative offset values that are added to the reference signal power. This intermediary approach simplifies the control signaling and power management complexity.
3Speed
If transmission power control data is reported frequently, then power control responsiveness is improved, but signaling overhead increases
Solution Approach 1:
The patent applies partial power control by only dynamically adjusting control signals and data signals, while keeping reference signals at fixed power. This partial application of dynamic control reduces the frequency and amount of power control signaling required compared to controlling all uplink signals dynamically, thereby reducing overhead while maintaining essential responsiveness.
Data Source
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AI summary
A base station apparatus for a mobile communication system is disclosed that includes a unit to receive an uplink reference signal transmitted from user equipment, a unit to provide transmission power control data indicating whether a transmission power value of the uplink reference signal to be transmitted later is to be changed, a unit to derive a first offset power value so that the uplink control signal is transmitted at a power value determined by adding the first offset power value to the transmission power value of the uplink reference signal, a unit to derive a second offset power value so that the uplink control signal is transmitted at a power value determined by adding the second offset power value to the transmission power value of the uplink reference signal, and a unit to report the data and values to the user equipment.