ECC Symbol Modification for Lower PAPR and Bit Errors
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Solution Overview
Problem
Modem communication systems face issues with high Peak-to-Average Power Ratios (PAPR) and bit-error rates, particularly in noisy environments, leading to distortion and reduced bandwidth, which existing solutions like clipping and modulation scheme downgrading attempt to address but with undesirable side effects.
Innovation Solution
The method involves intentionally modifying symbols in the bitstream after error correction encoding but before transmission to optimize communication metrics such as reducing PAPR or error rates by changing symbols to lower power levels or more distinguishable constellation points, utilizing the extra correction capacity of Error Correction Codes (ECC) to achieve these goals without clipping or downgrading modulation schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If clipping is used to reduce PAPR, then PAPR is reduced, but distortion and adjacent channel interference are introduced
Solution Approach 1:
The patent applies preliminary action by modifying symbols in advance before transmission to reduce PAPR. Specifically, symbols with high power levels are identified and changed to alternative symbols with lower power levels before the signal is transmitted, preventing the need for clipping at the transmitter or receiver, thus avoiding distortion and interference while achieving PAPR reduction
2Reliability
If modulation scheme downgrading is used to reduce bit-error rates, then bit-error rates are reduced, but data rate is reduced
Solution Approach 1:
The patent applies local quality by selectively modifying only certain symbols that are prone to errors (e.g., symbols with high power levels or symbols that are close to decision boundaries in the constellation diagram) while leaving other symbols unchanged. This targeted approach improves reliability for problematic symbols without reducing the overall data rate, as the modification is localized to specific symbols rather than requiring a general downgrading of the modulation scheme
3Power
If symbols are modified to reduce PAPR or error rates, then PAPR and error rates are reduced, but bit errors are intentionally introduced
Solution Approach 1:
The patent applies blessing in disguise by intentionally introducing controlled modifications to symbols, which appear as errors, but these modifications are actually beneficial because they reduce PAPR and improve overall system performance. The ECC decoder at the receiver end corrects these intentional modifications, converting what would be harmful bit errors into beneficial PAPR reduction, thus improving both power efficiency and reliability
Data Source
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AI summary
Disclosed in some examples are methods, systems, devices, and machine-readable mediums which optimize one or more metrics of a communication system by intentionally changing symbols in a bitstream after encoding by an error correction coder, but prior to transmission. The symbols may be changed to meet a communication metric optimization goal, such as decreasing a high PAPR, reducing an error rate, reducing an average power level (to save battery), or altering some other communication metric. The symbol that is intentionally changed is then detected by the receiver as an error and corrected by the receiver utilizing the error correction coding.