Power Grid Modem Interleaver for Burst Error Distribution
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Solution Overview
Problem
Modems operating on low voltage power grids face challenges with high concentrations of signal errors due to noise bursts, which overwhelm error correction techniques like convolutional codes, and existing interleavers do not effectively distribute errors across time and frequency windows, leading to poor data transmission and reduced throughput.
Innovation Solution
Selecting an interleaver block size that is approximately one-half of the frequency cycle of the power grid communication medium to distribute signal errors evenly, eliminating the need for frequent voltage zero crossing measurements and utilizing this block size to rearrange data bits across time and frequency, thereby reducing error density peaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional interleavers are used to distribute signal errors, then error correction performance improves, but error concentration in contiguous regions remains too high for effective correction
Solution Approach 1:
The patent segments the signal transmission into discrete symbols that are sequentially mapped to different frequency carriers. By dividing the contiguous error-prone region into separate symbol segments transmitted across different frequencies, the interleaver can distribute errors more effectively. Each symbol segment is treated independently and mapped to different carriers, breaking up the error concentration that would otherwise affect contiguous time-frequency regions.
Solution Approach 2:
The patent transitions from one-dimensional error distribution (contiguous time or frequency) to two-dimensional distribution across both time and frequency dimensions. Symbols are sequentially transmitted in time but mapped to different frequency carriers, creating a time-frequency spread that distributes errors across multiple dimensions. This dimensional expansion allows error correction codes to operate more effectively by preventing error concentration in any single dimension.
2Reliability
If interleaver block size is increased to distribute errors more widely, then error density peaks are reduced, but data transmission throughput decreases
Solution Approach 1:
The patent employs dynamic interleaving where the mapping of symbols to frequency carriers adapts based on channel conditions and error patterns. Rather than using a fixed, overly conservative block size that would reduce throughput, the system dynamically adjusts the interleaving parameters to achieve sufficient error distribution while maintaining higher transmission rates. This dynamic approach allows optimization of both reliability and throughput based on real-time conditions.
Solution Approach 2:
The patent changes the interleaver block size parameter based on observed error patterns and channel conditions. Rather than using a fixed large block size that would always reduce throughput, the system adjusts the block size parameter dynamically - using smaller blocks when throughput is prioritized and larger blocks when error distribution is more critical. This parameter adaptation resolves the contradiction by allowing the system to achieve adequate error distribution with smaller, less throughput-penalty block sizes.
3Reliability
If voltage zero crossing measurements are implemented to optimize transmission timing, then error distribution improves, but device complexity and hardware requirements increase
Solution Approach 1:
The patent implements self-service error distribution through the inherent structure of OFDM modulation and sequential symbol mapping. Rather than requiring external voltage zero crossing measurements to determine optimal transmission timing, the system uses its own signal structure - sequentially transmitting symbols that are mapped to different frequency carriers - to automatically achieve error distribution. The OFDM modulation and frequency carrier mapping provide built-in error protection without requiring additional measurement hardware or complex synchronization mechanisms.
Solution Approach 2:
The patent makes the frequency carriers serve multiple functions: they carry the modulated symbols for data transmission and simultaneously provide error distribution through their frequency diversity. The same frequency carriers that transmit the signal also act as the interleaving mechanism, eliminating the need for separate measurement and control systems. This multi-functionality resolves the contradiction by achieving error distribution through the existing transmission infrastructure rather than requiring additional hardware for voltage zero crossing measurements.
Data Source
AI summary
Methods and systems are disclosed for applying an interleaver that better distributes signal errors to be used in devices operating on low voltage power grids. One embodiment of a method comprises: determining a frequency cycle of the communication medium; setting an interleaver block size based on the frequency cycle of the communication medium; re-arranging bits in a data packet based on the interleaver block size; transmitting the re-arranged data packet over the communication medium to a receiver. Specifically, according to an embodiment, the interleaver block size is set to one-half of the frequency cycle of the communication medium.