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Updated: May 21, 2026

07:45
Quasi-light Storage for Optical Data Packets
Published on: February 6, 2014
16QAM transmission with 5.2 bits/s/Hz spectral efficiency over transoceanic distance
H Zhang1, J-X Cai, H G Batshon
1TE SubCom, 250 Industrial Way West, Eatontown, New Jersey 07724, USA. HZhang@subcom.com
Optics Express
|June 21, 2012
Summary
This study demonstrates error-free transmission of 160 channels using Pulse Amplitude Modulation (PAM) over 6,860 km. Advanced coding and iterative decoding enabled processing over 12 billion bits with high spectral efficiency.
Area of Science:
- Optical communication systems
- Digital signal processing
Background:
- High-capacity optical transmission systems are crucial for modern data networks.
- Achieving high spectral efficiency over long distances presents significant challenges.
Purpose of the Study:
- To investigate the feasibility of transmitting multiple high-order Quadrature Amplitude Modulation (QAM) channels over extended fiber optic links.
- To evaluate the performance of advanced error correction techniques in mitigating transmission impairments.
Main Methods:
- Transmission of 160 channels of Pulse Amplitude Modulation (PAM) with 16-level Quadrature Amplitude Modulation (QAM) and Return-to-Zero (RZ) pulse shaping.
- Utilizing a spectral efficiency of 5.2 bits/s/Hz over a 6,860 km transmission distance.
- Employing coded modulation with iterative decoding, including a Maximum A Posteriori (MAP) decoder and Low-Density Parity-Check (LDPC) based Forward Error Correction (FEC).
Main Results:
- Successful transmission of 160 channels with 16-QAM modulation.
- Achieved a spectral efficiency of 5.2 bits/s/Hz.
- Processed over 3 billion 16-QAM symbols (12 billion bits) without any residual errors after decoding.
Conclusions:
- Coded modulation combined with iterative MAP and LDPC-based FEC decoding effectively eliminates errors in high-capacity optical transmission.
- This approach enables reliable data transmission at high spectral efficiencies over long-haul fiber optic networks.
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