Optical System PAPR Reduction via Symbol Modification
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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 OFDM systems like 4G LTE and IEEE 802.11 networks, leading to distortion and interference, and current solutions like clipping or downgrading modulation schemes are inefficient.
Innovation Solution
Intentionally modifying symbols in the bitstream after error correction encoding but before transmission to optimize communication metrics such as reducing PAPR or bit-error rates, by changing symbols to lower power levels or distributing them to reduce peak powers, using ECC 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 interference increase
Solution Approach 1:
The patent applies preliminary action by modifying the coded bitstream before transmission to preemptively reduce PAPR. The optimizer changes symbols in the bitstream after error correction encoding but before modulation and transmission, preparing the signal in advance to have lower peak power values, thereby avoiding the need for clipping that would cause distortion and interference.
2Power
If modulation schemes are downgraded to reduce PAPR, then PAPR is reduced, but data rate decreases
Solution Approach 1:
The patent applies parameter changes by modifying the bitstream parameters (symbols) after error correction encoding to achieve PAPR reduction without changing the fundamental modulation scheme. The optimizer changes specific symbol values in the coded bitstream while maintaining the same modulation order, thereby reducing peak power values while preserving the data rate capability of the original modulation scheme.
3Power
If deliberate bit flipping is used to reduce PAPR, then PAPR is reduced, but bit error rate increases
Solution Approach 1:
The patent applies preliminary action by performing deliberate bit flipping (symbol modification) in advance, after error correction encoding but before transmission. The optimizer identifies and modifies specific symbols that contribute to high PAPR, and these modifications are compensated for by the error correction decoder at the receiver, which corrects the intentionally introduced errors, thereby reducing PAPR while maintaining acceptable bit error rate performance.
Solution Approach 2:
The patent uses the error correction code as an intermediary mechanism. The ECC acts as a mediator that allows deliberate bit flips to be introduced into the bitstream while ensuring that the original data can still be recovered. The error correction decoder at the receiver identifies and corrects the intentionally modified symbols, enabling PAPR reduction without permanent degradation of bit error rate.
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.