A Digital Subcarrier Multiplexing Technique for Increased Spectral Efficiency in Optical Systems Using Direct Detection

2010 ◽  
Author(s):  
O. Gaete ◽  
L.D. Coelho ◽  
B. Spinnler ◽  
S. Hellerbrand ◽  
E.-D. Schmidt ◽  
...  
Keyword(s):  
Spectral Efficiency ◽  
Direct Detection ◽  
Optical Systems ◽  
Subcarrier Multiplexing ◽  
Digital Subcarrier Multiplexing

scholarly journals Complex Signal Mapping for Improving Spectral Efficiency of Li-Fi Systems

2019 ◽  
Vol 3 ◽  
pp. 58-62
Author(s):  
Ibrahim K. Sileh ◽  
Ayad A. Abdulkafi ◽  
Mohammed K. Hussein ◽  
Saad M. Hardan
Keyword(s):  
Spectral Efficiency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Direct Detection ◽  
Average Power ◽  
Visible Light Communication ◽  
Optical Systems ◽  
Complex Signal ◽  
Transmission Scheme ◽  
New Approach ◽  
High Spectral Efficiency

Light fidelity (Li-Fi) systems based on the orthogonal frequency division multiplexing (OFDM) scheme have gained more attention in the communications circles, as a means to provide high spectral efficiency and ensure stricter data rate requirements for visible light communication (VLC) systems. However, common OFDM schemes employ Hermitian symmetry to obtain a real-valued signal which is necessary in intensity modulation and direct detection (IM/DD) optical systems, at the expense of doubling the required bandwidth. In this paper, a novel transmission scheme for an OFDM-based Li-Fi system is proposed to tackle the issue in question. A new approach to complex signal mapping (CSM), based on the pairing function method, has been developed for Li-Fi systems. It does not require Hermitian symmetry and, hence, saves about 50% of the required bandwidth. Unlike existing OFDM-based VLC approaches, the proposed scheme employs CSM to ensure a real and positive signal without Hermitian symmetry in order to fully utilize the bandwidth available to Li-Fi networks. Simulation results show that the proposed scheme significantly outperforms other systems in terms of spectral efficiency. The CSM-OFDM based Li-Fi system also achieves a good peak-to-average power ratio (PAPR) reduction with acceptable bit-error-rate (BER) performance, compared to conventional approaches.

Unique Word DMT Schemes for Optical Systems With Intensity Modulation and Direct Detection

2017 ◽  
Vol 35 (18) ◽  
pp. 3862-3869 ◽  
Author(s):  
Sher Ali Cheema ◽  
Emilio Rafael Balda ◽  
Mike Wolf ◽  
Martin Haardt
Keyword(s):  
Direct Detection ◽  
Intensity Modulation ◽  
Optical Systems ◽  
Unique Word

scholarly journals Spectral Efficiency Optimization in Flexi-Grid Long-Haul Optical Systems

2015 ◽  
Vol 33 (13) ◽  
pp. 2735-2742 ◽  
Author(s):  
Tommaso Foggi ◽  
Giulio Colavolpe ◽  
Alberto Bononi ◽  
Paolo Serena
Keyword(s):  
Spectral Efficiency ◽  
Optical Systems ◽  
Efficiency Optimization
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