ECC Symbol Changes for OFDM PAPR and Error-Rate Optimization
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Solution Overview
Problem
Modern communication systems face issues with high Peak-to-Average Power ratios (PAPR) and bit-error rates, particularly in OFDM-based systems like 4G and 5G networks, leading to distortion and interference, and current solutions like clipping or downgrading modulation schemes are inefficient.
Innovation Solution
The system intentionally modifies symbols in the bitstream before transmission using error correction codes to optimize communication metrics such as reducing PAPR or bit-error rates by changing symbols to lower power levels or more discriminable constellation points, utilizing the ECC's correction capacity to maintain data integrity.
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 before transmission to prevent high PAPR from occurring in the first place. The transmitter proactively changes symbols to values that will result in lower power levels, eliminating the need for clipping and avoiding the associated distortion and interference problems.
Solution Approach 2:
The patent converts the harmful effect of symbol modifications (which normally would be considered errors) into a beneficial outcome. By intentionally modifying symbols to reduce PAPR and using error correction codes to handle the apparent errors, the system transforms what would be harmful distortion into a useful power reduction mechanism.
2Reliability
If modulation schemes are downgraded to reduce bit-error rates, then bit-error rates are reduced, but data rate decreases
Solution Approach 1:
The patent applies preliminary action by proactively modifying symbols before transmission to make them more discriminable and less susceptible to errors. By changing symbols to values that will result in more discriminable constellation points, the system reduces bit-error rates without needing to downgrade the modulation scheme, thereby maintaining high data rates.
Solution Approach 2:
The patent changes the parameters of symbols (their values or representations) to optimize both reliability and productivity. By selecting symbol values that map to more discriminable constellation points, the system improves error performance while maintaining the original modulation order and data rate.
3Power
If symbols are modified to reduce PAPR, then PAPR is reduced, but error rate may increase without ECC
Solution Approach 1:
The patent introduces error correction codes as an intermediary mechanism between symbol modification and error detection/correction. The ECC acts as a mediator that handles the apparent errors introduced by symbol modifications, allowing the system to reduce PAPR through proactive symbol changes while maintaining reliability through error correction.
Solution Approach 2:
The patent converts the harmful effect of symbol modifications (which would normally increase error rates) into a beneficial outcome by using error correction codes. The modifications that would create errors are actually useful for reducing PAPR, and the ECC system transforms these apparent errors into correctable events, achieving both power reduction and maintained reliability.
Data Source
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.