Cable Resistance Determination for Base Station Power Delivery
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Solution Overview
Problem
The significant power loss in power cables connecting remote radio heads to baseband units in cellular base stations, especially during backup battery operation, necessitates a cost-effective method to determine the resistance of the power cable, which changes over time due to environmental factors, to maintain constant voltage and reduce power dissipation.
Innovation Solution
A programmable power supply system coupled with a processing system that estimates the resistance of the power cable by varying output voltages and currents, using equations to calculate resistance without needing to know the power consumption of the remote radio head, and employing methods to maintain constant power consumption, such as broadcasting a constant envelope and frequency test tone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the resistance of the power cable is measured only when the cellular base station is constructed, then the measurement is simple and cost-effective, but the resistance value becomes inaccurate over time due to environmental effects
Solution Approach 1:
The system performs preliminary resistance measurement during construction to establish a baseline value, then uses this preliminary measurement as the foundation for ongoing operational measurements. This allows the system to maintain measurement capability without requiring complete re-measurement, balancing simplicity with accuracy over time.
Solution Approach 2:
The system continuously monitors power consumption and uses feedback from actual operational data to adjust and refine resistance measurements. By comparing expected power consumption with actual measurements, the system can detect resistance changes due to environmental effects and update its resistance value accordingly, maintaining accuracy without adding complex measurement circuitry.
2Measurement precision
If additional circuitry is added to the power supply to characterize the resistance of the power cable, then the resistance measurement accuracy improves, but the cost of the cellular base station increases
Solution Approach 1:
The power supply system uses its existing operational parameters (voltage, current, power consumption) to self-determine cable resistance without requiring external measurement devices. The system leverages normal operational data to calculate resistance, making the existing circuitry serve dual purposes: power delivery and resistance characterization.
Solution Approach 2:
The existing power supply circuitry is made multi-functional by using it both for power delivery and for resistance measurement. The same voltage and current measurement capabilities used for normal power management are repurposed to characterize cable resistance, eliminating the need for dedicated measurement circuitry.
3Loss of energy
If the voltage provided to the power cable is increased to reduce current, then power dissipation in the cable decreases, but the risk of voltage instability increases due to varying power consumption of the remote radio head
Solution Approach 1:
The system dynamically adjusts the voltage provided to the power cable based on real-time measurements of cable resistance and remote radio head power consumption. Rather than using a fixed high voltage that could cause instability, the system continuously adapts the voltage level to maintain optimal power delivery while compensating for resistance variations and load changes.
Solution Approach 2:
The system changes the operating parameters (voltage and current) based on measured cable resistance and power consumption conditions. By calculating the optimal voltage-current combination that minimizes power loss while maintaining voltage stability, the system adapts its power delivery parameters to the actual environmental and load conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for accurate determination of power cable resistance, reducing power dissipation and extending the operating time of cellular base stations on battery backup, while being less costly than previous solutions by eliminating the need for additional circuitry or increased battery capacity.
Implementation Method 1
the resistance of the power cable must be known. Although the resistance can be measured when the cellular base station is constructed, the resistance can change over time due to environmental effects
Implementation Method 2
the current drawn and hence the voltage provided to the remote radio head vary over time. To maintain a constant voltage at the input of the remote radio head, the resistance of the power cable must be known
Data Source
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AI summary
In one embodiment, a method is provided. The method comprises: setting a first voltage level provided to a cable; operating a radio, coupled to the cable, with constant power consumption; measuring a first current level provided to the cable; setting a second voltage level provided to the cable; measuring a second current level provided to the cable; and determining a first resistance of the cable using the first and second voltage and current levels.