Bit Error Ratio Tests with Two-Sided Frequentist Intervals
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Solution Overview
Problem
The margining operation in communication devices to determine optimal time/voltage slices for bit detection can be lengthy and inefficient, particularly when using large numbers of bits per test, leading to potential infinite tests or non-convergence issues due to reliance on BER tests with inadequate exit criteria.
Innovation Solution
Implementing a two-sided bit error ratio frequentist confidence interval (FCI) as an exit criterion to ensure convergence at a target confidence level, allowing the margining operation to terminate when a calculated two-sided bit error ratio FCI meets a threshold size, thereby controlling the duration and accuracy of BER tests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If large numbers of bits per test are used in BER tests, then measurement precision of BER estimates is improved, but test duration increases and convergence cannot be guaranteed
Solution Approach 1:
The patent changes the parameter of test exit criteria from fixed bit counts to dynamic confidence interval-based termination. The test continues until the confidence interval width falls below a threshold, allowing adaptive termination that balances precision and time. This resolves the contradiction by enabling early termination when sufficient precision is achieved without committing to fixed large bit counts.
Solution Approach 2:
The patent implements feedback by continuously monitoring the confidence interval width during testing and using it to determine termination. The exit criterion provides feedback about measurement precision, allowing the system to stop when the desired precision level is reached, thus avoiding unnecessary extended testing while ensuring adequate accuracy.
2Device complexity
If BER tests use inadequate exit criteria, then test simplicity is maintained, but reliability of convergence is worsened due to potential infinite tests
Solution Approach 1:
The patent changes the exit criterion parameter from simple fixed-count termination to confidence interval-based termination. While this increases computational complexity slightly, it guarantees convergence by ensuring the test stops when statistical precision requirements are met, eliminating the risk of infinite tests while maintaining practical simplicity through automated calculation.
Data Source
AI summary
An example communications device may include a slicer that may generate a digital output signal by thresholding a received signal according to variably set timing and voltage parameters. Testing circuitry may determine expected bit error ratios for multiple time-voltage slicer by performing test operations corresponding respectively to the multiple time-voltage slices. Each of the test operations may include setting the timing and voltage parameters of the slicer based on the corresponding time-voltage slice, periodically measuring a number of total bits and a number of erroneous bits based on the digital output signal and calculating a two-sided bit error ratio frequentist confidence interval (FCI) size from the measured bit error ratio. The measured bit error ratio is output in response to the two-sided bit error ratio FCI being less than or equal to a two-sided bit error ratio interval target size.