Wireless Receiver Radar Interference Detection Without Aliasing
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Solution Overview
Problem
Current wireless communication systems face challenges in accurately detecting interference from co-existing radar systems, leading to unnecessary frequency vacating and reduced usable frequencies due to ambiguous signal strength measurements caused by image frequency conversion and aliasing effects.
Innovation Solution
A receiver design with a first and second branch-off element and an element with a-priori known attenuation values processes detection signals to differentiate between signal strengths, allowing precise identification of interfering frequencies by comparing differences with threshold values, thereby distinguishing between actual radar frequencies and converted frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If signal strength measurement is performed after analog-to-digital converter stage in the digital part, then the detection process is simplified, but the measurement precision deteriorates due to image frequency conversion and aliasing effects causing ambiguous frequency identification
Solution Approach 1:
The patent applies preliminary action by performing analog signal processing and interference detection before the analog-to-digital conversion stage. The receiver identifies radar interference in the analog domain using a signal strength meter and frequency discriminator, then uses this information to configure the digital processing parameters. This ensures that only relevant frequency bands are digitally processed, eliminating aliasing effects and image frequency conversion ambiguities while maintaining simplified detection through targeted digital processing.
2Reliability
If the wireless communication system vacates frequencies potentially used by radar systems, then interference with radar systems is avoided, but the number of usable frequencies for wireless communication is reduced
Solution Approach 1:
The patent replaces the conventional approach of vacating entire frequency bands with a more precise electronic/digital discrimination method. Instead of mechanically avoiding frequencies, the system uses a frequency discriminator in the analog part to identify specific radar frequencies, then digitally marks only those specific frequencies for avoidance. This substitution enables precise frequency identification and selective avoidance, maintaining reliability while maximizing the number of usable frequencies.
Solution Approach 2:
The patent changes the detection parameter from general signal strength thresholding to frequency-specific identification using a frequency discriminator. By analyzing the frequency characteristics of detected signals and comparing them against known radar frequency patterns, the system can distinguish between radar signals and legitimate wireless communication signals. This parameter change enables selective frequency avoidance based on actual radar presence rather than blanket frequency vacating.
Data Source
AI summary
A receiver and a method are applied in a wireless communication system for detecting interference with a coexisting radar system. A signal received from an antenna is fed through an analog part and a subsequent digital part of said receiver. The receiver has an element with a-priori known attenuation values for a predefined set of frequencies, a first branch-off element for deriving a first detection signal from the signal before the element and a second branch-off element for deriving a second detection signal from the signal after the element. The receiver processes the first and the second detection signal such that a difference between the first and second detection signal is comparable with a threshold value, where the threshold value depends on the a-priori known attenuation values of the element. Depending on the comparison result, a frequency is identified as interfering or not a co-existing radar system.