Phase-Offset Polar Constellation for Reducing PAPR
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Solution Overview
Problem
Existing digital communication systems, particularly those using OFDM modulation, face challenges with high peak-to-average power ratio (PAPR) which can lead to inefficiencies and robustness issues against phase variations, especially at high frequencies beyond 6 GHz.
Innovation Solution
A telecommunication method that utilizes a polar constellation with block modulation and controlled phase-rotation vectors to reduce the PAPR of multi-carrier symbols, without requiring phase information to be transmitted to the receiver, thereby enhancing robustness against phase variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If OFDM modulation is used, then spectral efficiency and robustness against channel time dispersion are improved, but PAPR increases leading to power amplifier inefficiency
Solution Approach 1:
The patent applies phase rotation to the OFDM signal in the time domain, transforming the signal parameters to reduce peak values. By multiplying the time-domain signal by a phase rotation factor e^jθ, the signal's amplitude characteristics are modified while maintaining its spectral properties, thereby reducing PAPR and improving power amplifier efficiency without sacrificing spectral efficiency
Solution Approach 2:
The patent performs preliminary phase rotation on the OFDM signal before power amplification. By pre-processing the signal to reduce its peak-to-average power ratio before it reaches the power amplifier, the system prepares the signal in advance to operate within the amplifier's efficient linear region, avoiding energy loss and distortion that would occur with high peak values
2Productivity
If conventional constellations are used, then data transmission capacity is maintained, but robustness against phase variations deteriorates at high frequencies
Solution Approach 1:
The patent introduces an asymmetric phase rotation parameter θ that is specifically designed to counteract phase variations. By applying a controlled asymmetric phase transformation to the constellation points, the system creates an offset that compensates for frequency-dependent phase shifts, thereby maintaining reliability in millimeter-wave and terahertz bands while preserving data transmission capacity
Solution Approach 2:
The patent implements a feedback mechanism where the receiver estimates the phase rotation parameter and feeds back information to the transmitter. This allows the system to adaptively adjust the phase rotation to match actual channel conditions, maintaining robustness against phase variations while ensuring accurate data recovery at high frequencies
3Loss of energy
If phase rotation is applied to reduce PAPR, then power amplifier efficiency is improved, but phase information must be transmitted to the receiver
Solution Approach 1:
The patent extracts the phase rotation parameter θ as a separate, explicitly signaled quantity that is independently communicated to the receiver. By separating the phase rotation information from the data payload and transmitting it through dedicated pilot symbols or overhead channels, the system avoids the need to embed phase information within the data stream, thereby maintaining power amplifier efficiency while minimizing information loss
Solution Approach 2:
The patent uses pilot symbols as an intermediary to convey phase rotation information to the receiver. These dedicated reference signals carry the necessary phase calibration data without interfering with the main data transmission, allowing the receiver to compensate for phase rotation effects and recover the original data accurately while maintaining efficient power amplifier operation
Data Source
AI summary
A telecommunications method includes transmitting a multicarrier symbol constructed from points of a polar constellation that are modulated in blocks and controlling at least one phase rotation vector of one of the modulated blocks of points in order to reduce the peak-to-average power ratio of the transmitted multicarrier symbol.