Small-Cell Base Station Power Control for Macro Interference
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Solution Overview
Problem
In mobile communication systems, small-cell base stations located near macro-cell base stations face challenges in handover processes due to high downlink specific reference signal power from macro-cells, making it difficult for mobile stations to locate in small cells, even when downlink signal power is adjusted to the maximum allowed level.
Innovation Solution
A base station apparatus for small-cell base stations measures interference levels from macro-cells and controls downlink transmission power to enhance the specific reference signal (CRS) while reducing other signals, maintaining total power equal to or below the maximum allowable level when interference is high.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the downlink transmission power of small-cell base station is increased to maximum allowed level, then the coverage of small cell is improved, but the interference to macro-cell base station cannot be reduced
Solution Approach 1:
The patent applies local quality by differentiating the power allocation across different signal types. Specifically, the downlink specific reference signal (CRS) is assigned enhanced power to improve small cell detectability and coverage, while other downlink transmission signals maintain reduced power levels to minimize interference to the macro-cell. This selective power distribution allows the small-cell base station to achieve sufficient coverage without generating excessive harmful interference to neighboring macro-cells.
2Difficulty of detecting and measuring
If the downlink specific reference signal power is enhanced, then mobile station can locate small cell more easily, but the total downlink transmission power exceeds maximum allowed level
Solution Approach 1:
The patent implements parameter changes by dynamically adjusting the power allocation parameters of different downlink signals based on interference conditions. When interference to the macro-cell exceeds a predetermined threshold, the system modifies the power parameters such that the downlink specific reference signal receives enhanced power allocation while other downlink signals are allocated reduced power. This parameter adjustment ensures the total power remains within maximum allowed levels while improving small cell detectability.
3Object-generated harmful factors
If the downlink transmission power is reduced to limit interference, then the interference to macro-cell is reduced, but the coverage and handover performance of small cell deteriorates
Solution Approach 1:
The patent resolves this contradiction by applying local quality to specific signal components. The downlink specific reference signal (CRS) is selectively enhanced in power to maintain reliable handover performance and small cell detectability, while other downlink transmission signals are reduced in power to limit interference to the macro-cell. This targeted approach ensures that the critical signals for handover and location maintain sufficient quality without requiring overall power increases that would cause excessive interference.
Data Source
AI summary
A base station apparatus capable of ensuring a sufficiently large coverage of a small cell while reducing a power of downlink signals from a small-cell base station so as to be equal to or smaller than an allowable maximum power is provided. The base station apparatus of the small-cell base station comprises measurement means of measuring an interference level from a macro cell located in a periphery of the own base station and transmission-power control means of controlling a downlink transmission power based on a measurement result of the interference level from the macro cell. The transmission-power control means controls to enhance the transmission power of a downlink specific reference signal (CRS) among the downlink transmission signals of the own base station and to lower the transmission power of signals except for the downlink specific reference signal under a condition that the downlink transmission power is equal to or smaller than an allowable maximum power, when the interference level is higher than a predetermined level.