Wireless Test Signal Chain for Precise SNR Across Aggregated Bandwidth
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Solution Overview
Problem
Current testing devices and methods fail to achieve a well-defined signal-to-noise ratio (SNR) within an aggregated bandwidth for devices under test with wireless communication capabilities, as per the 3GPP TS 36.521-1 V15.2.0 standards, due to the lack of effective generation and processing of artificial white Gaussian noise signals that meet tight ripple requirements.
Innovation Solution
A testing device comprising multiple signal generators, numerically controlled oscillators, white Gaussian noise generators, digital filters, adders, digital-to-analog converters, and an analog processor, which output and process digital baseband signals and noise signals to achieve a well-defined SNR by frequency shifting and compensating signals to ensure accurate and efficient SNR within the aggregated bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single noise generator and filter are used, then device complexity is reduced, but manufacturing precision of SNR cannot be achieved within aggregated bandwidth
Solution Approach 1:
The patent divides the noise generation system into multiple independent channels (at least two), each with its own noise generator, digital filter, and signal generator. This segmentation allows each channel to be optimized for specific frequency ranges while maintaining overall SNR precision across the aggregated bandwidth, resolving the contradiction between precision and complexity.
Solution Approach 2:
The patent combines multiple processed noise signals and signal paths through analog addition in the analog processor. By merging the outputs of multiple independently processed channels, the system achieves comprehensive coverage of the aggregated bandwidth with precise SNR control, balancing the need for precision with manageable system complexity.
2Manufacturing precision
If digital filtering is applied to white gaussian noise signals, then manufacturing precision of noise frequency response is improved, but device complexity increases due to multiple digital filters
Solution Approach 1:
The patent assigns specific digital filters to different noise signal channels, with each filter optimized for its designated frequency range. This segmentation of filtering functions allows precise control of the noise frequency response across the entire aggregated bandwidth while distributing the filtering complexity across multiple manageable components.
Solution Approach 2:
Each digital filter is designed with specific characteristics tailored to its assigned frequency range and signal path. This local optimization of filter properties ensures that each portion of the noise spectrum is processed with appropriate precision, achieving overall manufacturing precision without requiring a single overly complex filter.
3Productivity
If multiple signal paths are aggregated, then productivity of bandwidth coverage is improved, but measurement precision of SNR deteriorates due to ripple accumulation
Solution Approach 1:
The patent implements a feedback mechanism where the digital filters are designed with complementary transfer functions that account for the aggregation of multiple signal paths. The filter designs incorporate knowledge of how signals will combine, allowing the system to pre-compensate for potential ripple accumulation and maintain SNR measurement precision across the aggregated bandwidth.
Solution Approach 2:
The patent carefully controls and adjusts key parameters including the statistical independence of noise signals, the frequency offset values, and the filter transfer function characteristics. By optimizing these parameters, the system achieves high productivity in bandwidth coverage while preventing ripple accumulation that would degrade SNR measurement precision.
4Adaptability or versatility
If frequency offset is applied in digital domain, then adaptability of carrier frequency adjustment is improved, but manufacturing precision of carrier frequency deteriorates due to offset errors
Solution Approach 1:
The patent replaces direct analog frequency adjustment mechanisms with digital frequency offset application followed by analog compensation. This substitution allows flexible and adaptive carrier frequency adjustment through digital means while using the analog processor to compensate for any precision losses, achieving both adaptability and manufacturing precision.
Solution Approach 2:
The analog processor acts as an intermediary that receives digitally offset signals and performs precision frequency compensation. This intermediary component bridges the digital frequency adjustment stage and the final analog output, correcting any precision errors introduced by digital frequency offset while maintaining the adaptability benefits of digital control.
Data Source
AI summary
A testing device and a method for testing a device under test are provided. The testing device comprises at least two signal generators, at least two numerically controlled oscillators, at least two white gaussian noise generators, at least two digital filters, each of which comprising a respective transfer function Hi, at least two adders, at least two digital-to-analog converters, and an analog processor.