DAS Loop Gain Measurement via Test Signal Injection
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Solution Overview
Problem
Distributed antenna systems (DAS) face instability due to loop gain issues, where energy feedback from downlink paths to uplink paths causes signal distortion and oscillation, leading to under-configuration and underutilization when designed based on worst-case generic loop gain assumptions.
Innovation Solution
Measuring actual loop gain by injecting a test signal from a disconnected downlink path to an RAU and measuring its power differential at a second contact point, allowing for determination of gain margin and optimization of DAS capacity and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If DAS is designed based on worst-case generic loop gain assumptions, then system stability is improved, but system capacity and performance deteriorate due to under-configuration and underutilization
Solution Approach 1:
The patent changes the parameter basis from generic worst-case loop gain assumptions to actual measured loop gain values. By measuring the real loop gain in the specific DAS configuration and using these actual values for design decisions, the system can be properly configured to achieve both stability and maximum capacity utilization, eliminating the conservative under-configuration caused by worst-case assumptions.
2Measurement precision
If loop gain measurement is implemented, then measurement precision is improved, but device complexity increases due to additional measurement equipment and procedures
Solution Approach 1:
The measurement system utilizes existing DAS components (signal sources, transmission paths, and receivers) to perform self-measurement of loop gain. The system injects test signals through existing infrastructure and measures the returned signals, eliminating the need for separate external measurement equipment and reducing overall system complexity while achieving precise measurements.
Data Source
AI summary
In a wireless distribution system, a test signal(s) having a first power level is injected from a first contact point. The test signal(s) is configured to propagate from the first contact point to a second contact point over a downlink path and an uplink path, thus creating a signal loop(s). A second power level of the test signal(s) is measured at the second contact point, and an actual loop gain of the wireless distribution system is determined by subtracting the first power level from the second power level. By determining the actual loop gain of the wireless distribution system, it is possible to further determine a gain margin of the wireless distribution system. Based on the gain margin, it is possible to determine optimization possibilities for the wireless distribution system to maximize capacity and performance of the wireless distribution system.