Error-Coded Symbol Changes for Lower PAPR and Bit Errors
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Solution Overview
Problem
Modern communication systems face challenges with high Peak-to-Average Power Ratios (PAPR) and bit error rates, particularly in noisy environments, which can lead to distortion and out-of-band interference.
Innovation Solution
The system intentionally modifies symbols in the bitstream after error correction encoding but before transmission, to optimize communication metrics such as reducing PAPR or bit error rates. This is achieved by changing symbols to lower transmission powers or to positions on the constellation map that are farther apart, thereby utilizing the extra capacity of error correction codes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If clipping is used to reduce PAPR, then peak power is reduced, but distortion and out-of-band interference occur
Solution Approach 1:
The patent applies preliminary action by modifying symbols in advance before transmission to reduce PAPR. The transmitter identifies symbols with high power contribution and replaces them with alternative symbols that have lower power, preventing the generation of high peak powers that would require clipping. This proactive approach eliminates the need for post-processing clipping operations that cause distortion.
Solution Approach 2:
The patent changes the parameters of symbols in the bitstream by replacing high-power symbols with alternative symbols that have different power characteristics. This parameter change approach modifies the power distribution of the signal to reduce PAPR without altering the fundamental signal structure, thereby avoiding the distortion and interference problems associated with clipping.
2Reliability
If modulation schemes are downgraded to reduce bit error rates, then error rates decrease, but data rates are reduced
Solution Approach 1:
The patent changes the spatial parameter of symbols by moving them to different positions on the constellation map that are farther apart. This increases the minimum distance between constellation points, making the signal more robust against noise and reducing bit error rates while maintaining the same modulation order and data rate.
Solution Approach 2:
The patent applies preliminary action by pre-modifying symbols to increase their separation distance on the constellation map before transmission. This proactive arrangement ensures that symbols are positioned to maximize noise immunity, reducing the need for lower-order modulation schemes and preserving data rates while improving reliability.
3Power
If symbols are modified to reduce PAPR, then peak power is reduced, but transmission power may be reduced
Solution Approach 1:
The patent changes the power parameter of selected symbols by replacing them with alternative symbols that have lower power contribution to the overall signal. This selective parameter change reduces the peak power and PAPR while the system compensates by adjusting the power levels of other symbols or using amplification to maintain the required average transmission power and signal quality.
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.