RF System PAPR Reduction via Symbol Modification

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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 LTE 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

VSEngineering Contradiction Analysis

1Power

If clipping is used to reduce PAPR, then PAPR is reduced, but distortion and adjacent channel interference are introduced

Engineering Contradiction:

ImprovePAPRVSAvoiddistortion and adjacent channel interference

Core Design Contradiction:

PowerVSObject-generated harmful factors

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 instantaneous power, avoiding the need for clipping and its associated distortion and interference problems.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the parameter values of symbols in the bitstream to optimize PAPR. Specifically, it modifies symbols to have values that will produce lower instantaneous power when transmitted, thereby reducing PAPR without introducing distortion or interference.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If modulation scheme is downgraded to reduce bit-error rate, then bit-error rate is reduced, but bandwidth is reduced

Engineering Contradiction:

Improvebit-error rateVSAvoidbandwidth

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent changes symbol parameters to values that are more discriminable and less susceptible to errors, thereby reducing bit-error rate while maintaining the same modulation scheme and bandwidth. This allows the system to improve reliability without sacrificing productivity.

Inventive Principle:

Principle #35Parameter changes

3Power

If symbols are modified to reduce PAPR, then PAPR is reduced, but bit-error rate may increase

Engineering Contradiction:

ImprovePAPRVSAvoidbit-error rate

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent carefully selects which symbols to modify and to what values, changing parameters to reduce PAPR while simultaneously considering the impact on error rate. By choosing symbol modifications that reduce power peaks but maintain or improve discriminability, it achieves PAPR reduction without increasing bit-error rate.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11172455B2Peak to average power output reduction of RF systems utilizing error correction

Publication Date: 2021.11.09 MICROSOFT TECHNOLOGY LICENSING LLC

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.