Active-Set Tone Reservation for PAR Reduction
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Solution Overview
Problem
Existing multicarrier transmission systems, such as OFDM, face high peak-to-average power ratios (PAR) that can lead to performance degradation due to nonlinear amplifier operation, and known solutions for reducing PAR often involve high computational overhead or inaccuracy.
Innovation Solution
An iterative method using a peak-canceling vector is employed, where a time-domain data vector is processed to reduce peak magnitudes by shifting and scaling a peak-reducing vector, iteratively balancing peak magnitudes until the PAR is within a target threshold, utilizing hardware or software processing blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tone reservation is used to reduce PAR, then amplifier linearity is improved, but computational overhead increases
Solution Approach 1:
The patent pre-calculates and stores peak-canceling vectors in a lookup table before transmission. During actual operation, the system only needs to query and apply the pre-computed vectors, eliminating the need for real-time complex calculations and significantly reducing computational overhead while maintaining PAR reduction effectiveness
Solution Approach 2:
The patent uses simplified models or representative signal characteristics to generate peak-canceling vectors that approximate the optimal solution without requiring full-signal processing. This copying approach reduces computational complexity while achieving sufficient PAR reduction for practical applications
2Manufacturing precision
If iterative peak cancellation is applied, then PAR reduction accuracy is improved, but processing time increases
Solution Approach 1:
The patent pre-computes peak-canceling vectors for various signal conditions and stores them in lookup tables. During transmission, the system quickly retrieves the appropriate pre-computed vectors based on current signal characteristics, achieving accurate PAR reduction without the time penalty of iterative real-time calculations
Solution Approach 2:
The patent implements a dynamic selection mechanism that adapts the processing approach based on signal conditions. For signals with moderate PAR, simpler methods are used, while for extreme cases, more sophisticated peak-canceling vectors are applied, optimizing the balance between accuracy and processing time
Data Source
AI summary
In an embodiment, a transmitter includes first and second processing blocks, which may each include hardware, software, or a combination of hardware and software. The first processing block is operable to generate a first peak-reducing vector. And the a second first processing block is operable to receive a first data vector, the data vector comprising a plurality of samples, the first data vector having a first peak with a first index and a first magnitude, a second peak with a second index and a second magnitude that is less than the first magnitude, and a first peak-to-average power ratio, and to generate a second data vector having a second peak-to-average power ratio that is lower than the first peak-to-average power ratio by using the first peak-reducing vector.