Network Node Intermodulation Detection via Transceiver Feedback
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Solution Overview
Problem
In wireless communication systems, passive intermodulation (PIM) products caused by nonlinear effects in radio frequency (RF) transmitters can lead to reduced signal-to-noise ratio (SNR) and decreased coverage due to interference from multiple transmitted signals, which existing technologies struggle to effectively detect and mitigate, especially in multi-operator FDD RBS sites and carrier aggregation setups.
Innovation Solution
A method for a network node to detect intermodulation interference by determining potentially interfering frequencies, transmitting requests to transceiver devices for signal level measurements, and correlating these measurements with estimated interference levels to determine the presence of intermodulation interference, using look-up tables or calculations based on the receive frequency and known frequency schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple FDD downlink bands are transmitted simultaneously, then network capacity and coverage are improved, but passive intermodulation products are generated that fall into receive bands and degrade receiver SNR
Solution Approach 1:
The network node proactively identifies frequencies that may generate PIM products before they cause interference. By calculating potential PIM frequencies based on transmit frequencies and detecting their presence in advance, the system can take preventive measures such as adjusting transmit power or frequency allocation before the interference degrades receiver performance
Solution Approach 2:
The system continuously monitors receive band interference levels and correlates them with transmit signal levels. When PIM interference is detected, the network node receives feedback about the interference condition and can adjust transmission parameters accordingly. This closed-loop feedback mechanism enables dynamic mitigation of PIM effects while maintaining network capacity
2Measurement precision
If manual inspection by service technician is performed to identify PIM sources, then accurate diagnosis is achieved, but network downtime increases and productivity decreases
Solution Approach 1:
The network node performs self-diagnosis by autonomously identifying frequencies that generate PIM products and detecting their presence in receive bands. The system automatically correlates transmit signal characteristics with received interference patterns, enabling the network to diagnose and mitigate PIM issues without external intervention, thus maintaining high network availability while achieving accurate diagnosis
Solution Approach 2:
The manual mechanical inspection process by service technicians is replaced with automated electronic detection and analysis systems. The network node uses signal processing algorithms to identify PIM sources and characteristics, substituting human-based diagnostic methods with automated electronic systems that operate continuously without causing network downtime
3Manufacturing precision
If external cavity filters are used to filter unwanted components, then transmit spectrum mask compliance is improved, but PIM products caused by multiple transmitted signals cannot be filtered and remain in receive band
Solution Approach 1:
Instead of relying solely on frequency-domain filtering, the system introduces a new dimension of detection by monitoring and correlating signal levels across different frequencies and time. The network node identifies PIM products by analyzing the relationship between transmit frequencies and receive band interference, enabling detection and mitigation of PIM effects that cannot be addressed by traditional frequency filtering alone
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 timely detection and mitigation of intermodulation interference, reducing the likelihood of dropped connections and improving network coverage by identifying and addressing interference issues before they significantly impact service.
Implementation Method 1
passive intermodulation (PIM) products caused by nonlinear effects in radio frequency (RF) transmitters can lead to reduced signal-to-noise ratio (SNR) and decreased coverage due to interference from multiple transmitted signals
Data Source
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AI summary
A method of a network node of a radio access network is provided for detecting interference caused by intermodulation on a receive frequency of the network node. The method comprises determining at least one frequency of a signal which potentially gives rise to an intermodulation product on the receive frequency. The method comprises transmitting a request to a transceiver device, wherein the request includes information about the determined at least one frequency and an instruction to monitor that at least one frequency. The method comprises estimating interference level at the receive frequency at one or more time instants. The method comprises receiving a measurement report from the transceiver device, wherein the measurement report includes information about signal levels on the at least one frequency at one or more time instants. The method comprises determining whether the signal on the at least one frequency is probable to cause intermodulation interference on the receive frequency based on the estimated interference level at the receive frequency and the measurement report. Corresponding method of a transceiver device, a network node and computer programs for implementing the methods are also disclosed.