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Performance of grey-coded IQM-based optical modulation formats on high-speed long-haul optical communication link
摘要： In this article the performance of grey-coded advanced optical modulation formats is evaluated on a single-channel high-speed long-haul optical communication link and are compared to the respective differential-coded modulation formats. Polarisation division multiplexed optical in-phase quadrature modulator (IQM) structure and homodyne detection scheme are used to realise 100 Gbps quadrature phase-shift keying (QPSK), 120 Gbps 16-ary quadrature amplitude modulation (16-QAM), 360 Gbps 32-QAM and 480 Gbps 64-QAM modulation formats. Advanced digital signal processing unit with various pre-processing and recovery stages such as direct current blocking, normalisation, low-pass Bessel filter, resampling, quadrature imbalance compensation, chromatic dispersion compensation, non-linear compensation, timing recovery, adaptive equalisation, down-sampling, frequency offset estimation, and carrier phase estimation is used at the receiving end to compensate for signal impairments during propagation. Maximum transmission distances of 7200, 1050, 560, and 360 km have been achieved at an acceptable bit error rate for QPSK, 16-QAM, 32-QAM, and 64-QAM, respectively. The grey-coded systems outperformed the differential-coded systems regarding optical signal-to-noise ratio requirement, receiver sensitivity, and transmission distance.
关键词： grey-coded,optical modulation formats,high-speed long-haul optical communication,homodyne detection,IQM,digital signal processing
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE International Conference on Signal Processing, Communications and Computing (ICSPCC) - Dalian, China (2019.9.20-2019.9.22)] 2019 IEEE International Conference on Signal Processing, Communications and Computing (ICSPCC) - Enabling technologies for high-speed LED based underwater visible light communications
摘要： Underwater optical wireless communication (UWOC) is an interesting area need to be explored. In recent years, underwater visible light communication (UVLC) is expected to act as an alternative candidate in next-generation underwater wireless optical communications for the Internet of Underwater Things. The challenge is that the absorption, scattering, diffraction effect and turbulence of water medium, which can bring large attenuation and nonlinearity penalty. Therefore, it needs to apply lots of advanced modulation formats which including orthogonal frequency division multiplexing (OFDM), discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S OFDM) and carrier-less amplitude and phase modulation (CAP) in UVLC signal system. What’s more, advanced digital processing algorithm such as pre/post equalization, nonlinear compensation and other algorithms based on artificial intelligence are needed. In this paper, we introduce three advanced modulation formats including DFT-S OFDM, OFDM and CAP employing probabilistic shaping for high-speed LED based underwater visible light communication.
关键词： underwater visible light communication,probabilistic shaping,advanced modulation formats
更新于2025-09-16 10:30:52
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Advanced Modulation Techniques for Flexible Optical Transceivers: the Rate/Reach Trade-off
摘要： This tutorial paper reviews advanced modulation techniques that have been proposed in the literature for the implementation of flexible (or reconfigurable) transceivers, which are fundamental building blocks of next-generation software-defined optical networks. Using a common reference multi-span propagation system scenario, the performance of transceivers employing standard quadrature-amplitude modulation with variable-rate forward error correction, probabilistic constellation shaping and time-domain hybrid formats is assessed, highlighting the achievable flexibility in terms of continuous trade-off between transmission rate and distance. The combination of these techniques with sub-carrier multiplexing, which enables an increase of the fiber nonlinearity tolerance thanks to the optimization of the symbol rate per sub-carrier, is also discussed.
关键词： coherent detection,Optical fiber communication,hybrid QAM,flexible optical transceivers,modulation formats,subcarrier multiplexing,probabilistic shaping
更新于2025-09-04 15:30:14
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Multi-Section Semiconductor Optical Amplifiers for Data Centre Networks
摘要： The ever-growing Internet based services and applications, involving a huge amount of computing and storage resources, have been powered by data centres (DC) [1]. The storage and movement of data within the DCs is driving the requirement for cost-effective, higher capacity inter- and intra- next generation DC networks [2]. Within the context of these next generation DC networks, the ability to transmit very high data rates (100 – 400 Gb/s) over both short and long distances (intra or inter DC fibre links) is one of the main challenges (within the optical sector. The modulation format that is currently touted as the most suitable for such high capacities is 4-level pulse amplitude modulation (PAM4), which carries 2 bits per symbol. Optical amplification is needed for reach extension for inter- and intra- DC communications, Semiconductor optical amplifiers (SOAs) are needed to realize a low cost amplification solution. SOAs possess many advantages, including low power consumption, small footprint, wide bandwidth, being integrateable, and the ability to accommodate wavelength ranges beyond the scope of Erbium doped fibre amplifiers. However, the use of SOAs for linear amplification of C-band optical signals is still relatively limited, mainly due to the relatively large noise figure (NF) associated with them compared to erbium doped fiber amplifiers and low saturation powers of about 10 mW. Multi-section SOAs are known to possess superior NFs and larger saturation powers than an equivalent single-section SOA [3], and hence may provide performance benefit for reach extension for DC networks. In this work, we examine the use of a multi-section semiconductor optical amplifier (MS-SOA) [3] to provide an improvement in its use as a linear amplifier compared to a single section SOA. The MS-SOAs have been shown to have superior noise and linearity performance compared with single section SOAs. We configure the MS-SOA to operate in the low-NF mode with high saturation power mode and the equivalent single-section SOA. We compare the input power dynamic range for the MS-SOA and equivalent single-section SOA. We expect an improvement in the input power dynamic range of at least 3 dB [4]. The combination of a lower NF and higher saturation power enables crosstalk-free amplification of simultaneous multi-wavelength channels using the same SOA device.
关键词： multi-section semiconductor optical amplifier,advanced modulation formats,data centre networks
更新于2025-09-04 15:30:14