OFDM Modulator Matrix Operations Reduce PAPR
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Solution Overview
Problem
OFDM communication systems face challenges in reducing Peak-to-Average Power Ratio (PAPR), which requires complex phase control of subcarriers and amplifiers with wide linearity to prevent distortion, and also suffer from additive noise affecting bit error rates.
Innovation Solution
A communication apparatus and method that employs specific non-singular matrices for modulating and demodulating signals in OFDM systems, simplifying the process by generating baseband signals through matrix operations that reduce PAPR and suppress additive noise, thereby improving bit error rates without the need for repeated phase control calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If phase control of subcarriers is implemented to reduce PAPR, then PAPR is reduced, but device complexity increases due to repeated calculations
Solution Approach 1:
The patent transforms the phase control problem from a sequential decision process into a matrix multiplication operation. By representing phase rotations as diagonal matrices and applying them to the subcarrier modulation signal, the system achieves PAPR reduction through linear algebra operations that are more efficient than repeated sequential calculations.
Solution Approach 2:
The patent replaces the mechanical/sequential phase control process with a mathematical matrix operation system. Instead of iteratively adjusting phases through sequential decisions, the system uses predetermined transformation matrices that can be applied directly to the signal vector, substituting a complex control mechanism with a streamlined mathematical transformation.
2Reliability
If amplifiers with wide linearity range are used to transfer signals without distortion, then signal fidelity is improved, but device complexity and cost increase
Solution Approach 1:
The patent performs preliminary PAPR reduction through matrix-based phase control before the signal reaches the amplifier. By reducing peak values in advance through transformation matrices applied to the subcarrier signal, the system prepares the signal to be more amplifier-friendly, allowing standard amplifiers to operate more efficiently without requiring wide linearity ranges.
3Loss of energy
If sequential decision procedure is used to calculate optimal phase, then PAPR reduction is achieved, but processing time increases
Solution Approach 1:
The patent replaces the time-consuming sequential decision procedure with direct matrix multiplication operations. The transformation matrices are predetermined and can be applied in parallel to all subcarriers simultaneously, eliminating the iterative nature of sequential calculations and significantly reducing processing time while achieving the same PAPR reduction effect.
4Ease of operation
If matrix operations are used for modulation and demodulation, then processing is simplified, but computational requirements change
Solution Approach 1:
The patent changes the computational approach from sequential phase adjustments to matrix multiplications. While matrix operations require computational resources, they can be implemented efficiently using standardized linear algebra libraries and hardware accelerators, transforming the computational burden into a more manageable form that benefits from optimized mathematical routines rather than complex control logic.
Data Source
AI summary
A modulator generates a modulation signal from an input signal. A serial-parallel converter generates a subcarrier modulation signal from the modulation signal. A first operator generates first data by multiplying a predetermined non-singular matrix by the subcarrier modulation signal. A second operator generates second data by multiplying a matrix calculated by multiplying a predetermined transformation matrix by the predetermined non-singular matrix by the subcarrier modulation signal, or multiplying the predetermined transformation matrix by the first data. A synthesizer generates a baseband signal from data obtained by adding the second data to the first data, or data obtained by subtracting the second data from the first data. A transmitter generates a transmission signal from the baseband signal, and transmits the transmission signal to another apparatus via an antenna.