OFDM Signal Precoding for PAPR Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current OFDM communication systems face challenges with high Peak to Average Power Ratio (PAPR), leading to expensive power amplifiers and signal distortion, while existing methods either reduce communication capacity or degrade decoding performance.
Innovation Solution
The method involves performing precoding in the time domain on data symbols using a specific precoding matrix before spreading in the frequency domain, which reduces PAPR without affecting system performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If OFDM is used for high-speed transmission, then transmission speed is improved, but PAPR increases leading to expensive power amplifiers and signal distortion
Solution Approach 1:
The patent applies precoding in the time domain before OFDM modulation as a preliminary action to reduce PAPR. By transforming data symbols through a precoding matrix before spreading in frequency domain, the signal's peak power is reduced in advance, allowing the use of cheaper power amplifiers while maintaining high-speed transmission capability
Solution Approach 2:
The patent changes the signal processing parameters by introducing time-domain precoding with specific precoding matrices before the standard OFDM process. This parameter change transforms the signal characteristics to achieve lower PAPR while preserving the high-speed transmission advantage of OFDM
2Ease of manufacture
If PAPR reducing schemes are applied, then power amplifier cost is reduced, but OFDM system performance is affected
Solution Approach 1:
By performing precoding before spreading and modulation, the patent reduces PAPR at the source without requiring post-processing or clipping operations that would degrade performance. This preliminary action maintains signal integrity while achieving cost reduction
3Ease of manufacture
If signal generating schemes are changed to reduce PAPR, then power amplifier cost is reduced, but decoding rate decreases
Solution Approach 1:
The precoding is applied as a preliminary transformation that prepares the signal for transmission without altering the underlying data structure or requiring complex decoding operations. This maintains the original decoding rate while achieving PAPR reduction
Solution Approach 2:
The patent changes the signal generation parameters through precoding matrices while preserving the fundamental OFDM structure and data encoding, ensuring that decoding performance remains unaffected
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An apparatus for transmitting data using a plurality of carriers and method thereof are disclosed, by which PAPR improving effect is enhanced. A method of generating an OFDM signal, which is transmitted by spreading data symbols using a DFT (Discrete Fourier Transform) matrix, according to the present invention includes the steps of generating an output symbol by data-processing the data symbols in time domain in a manner of giving a specific weight to the data symbols and summing up the weight-given data symbols and generating the OFDM signal by performing OFDM data processing on the output symbol.