Base Station Pilot Signal Power Variation for Interference Reduction
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Solution Overview
Problem
In dense small-cell environments, the high interference from neighboring small-cell base stations can hinder the detection of pilot signals from macro-cell base stations, leading to inefficient resource utilization and reduced coverage areas in mobile communication systems.
Innovation Solution
Base stations and self-organizing network (SON) servers generate pilot signals with power variations between a first and second power level, allowing nearby user equipment to perform cell selection and re-selection by adjusting the power levels of pilot signals based on stored patterns and received radio parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pilot signals are transmitted at constant power levels to provide fixed reference for mobile stations, then coverage area definition becomes clear and simple, but interference level from base stations increases
Solution Approach 1:
The patent applies periodic action by implementing time-variant power levels for pilot signals instead of constant power levels. The base station transmits pilot signals with power that varies periodically over time, allowing mobile stations to detect coverage areas during specific time intervals when interference is reduced, thereby resolving the contradiction between clear coverage definition and interference reduction
Solution Approach 2:
The patent implements dynamics by transitioning from static constant power levels to dynamic time-variant power levels for pilot signal transmission. The power level becomes a time-dependent parameter that adapts to changing interference conditions, enabling mobile stations to perform measurements when interference is minimal while maintaining clear coverage area boundaries
2Area of stationary object
If a large number of small cells are densely installed in a limited area to improve coverage, then service coverage is enhanced, but interference between neighboring small cells and macro cells increases
Solution Approach 1:
By implementing periodic power variations in pilot signal transmission across multiple cells, the patent enables time-division multiplexing of measurements. Mobile stations can measure pilot signals from different cells at different time intervals when interference from other cells is reduced, allowing dense cell deployment without excessive interference
Solution Approach 2:
The dynamic time-variant power levels allow the system to adapt to the dense small-cell environment by adjusting transmission characteristics over time. This enables more cells to operate in a limited area while maintaining acceptable interference levels through temporal separation of measurement opportunities
3Object-generated harmful factors
If orthogonal frequency reuse or correlation with orthogonal sequence techniques are used to mitigate interference, then interference between cells is reduced, but resource utilization efficiency degrades
Solution Approach 1:
The patent changes the power level parameter of pilot signals over time instead of using frequency domain separation or orthogonal sequences. This time-domain approach allows all cells to use the same frequency resources while reducing interference through temporal power variations, thereby maintaining high resource utilization efficiency while mitigating interference
Data Source
AI summary
Technologies are generally described for generating pilot signal patterns in a base station, such as a small-cell base station, or a self-organizing network (SON) in a mobile communication system. Example devices/systems described herein may include one or more of a storage unit, a control unit and/or a communication unit in a base station. The storage unit may be configured to store a pilot signal pattern corresponding to a power variation between a first power level and a second power level. The control unit may be coupled to the storage unit and configured to generate a pilot signal in accordance with the stored pilot signal pattern. Further, the communication unit may be coupled to the control unit and configured to transmit the generated pilot signal such that any nearby mobile stations (or user equipment) can use the signal to perform cell selection or re-selection.