DFT-Spread OFDM Modulation for Optical Signal PAPR Reduction
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Solution Overview
Problem
Optical OFDM transmission signals exhibit high Peak to Average Power Ratio (PAPR) due to non-linear effects in optical communication systems, leading to signal distortion and increased bit error rates, which degrade the performance of optical communication systems.
Innovation Solution
Implementing DFT-spread-OFDM modulation in both the transmission and reception apparatus to reduce the PAPR of optical signals, thereby suppressing distortion and improving reception quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional OFDM modulation is used for optical signal transmission, then high frequency spectrum utilization efficiency is achieved, but high PAPR causes serious signal distortion due to non-linear effects
Solution Approach 1:
The patent applies DFT-spread OFDM modulation which transforms the conventional OFDM signal by spreading each data symbol across multiple subcarriers using DFT coefficients. This parameter change in the modulation scheme reduces the PAPR from 10-30 dB to a lower level, thereby reducing signal distortion caused by non-linear optical effects while maintaining the high spectral efficiency of OFDM
2Speed
If conventional OFDM modulation is used, then long-distance and high-speed optical transmission is enabled, but high PAPR leads to increased bit error rate
Solution Approach 1:
By changing the modulation parameter from conventional OFDM to DFT-spread OFDM, the patent reduces the PAPR of the transmitted signal. This parameter change directly addresses the bit error rate issue by minimizing signal distortion in non-linear optical channels, enabling reliable high-speed long-distance transmission
Data Source
AI summary
An optical communication system, a transmission apparatus and a reception apparatus, and a transmission method and a reception method are provided. The transmission apparatus transmits an optical signal, and comprises: at least one encoder for encoding at least one data signal, respectively; at least one first modulator for performing first modulation on the at least one encoded data signal, respectively, and generating at least one first modulated signal; at least one second modulator for performing second modulation, which is DFT-spread-OFDM modulation, on the at least one first modulated signal, respectively, and generating at least one second modulated signal; and an up-converter for up-converting the at least one second modulated signal into the optical signal to be transmitted. Thus, a PAPR of the optical OFDM transmission signal is decreased, a signal distortion caused by non-linearity of optical devices is reduced, and a reception quality of the signal is improved.