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[Communications in Computer and Information Science] Futuristic Trends in Network and Communication Technologies Volume 958 (First International Conference, FTNCT 2018, Solan, India, February 9–10, 2018, Revised Selected Papers) || Future Perspectives in Elastic Optical Networks
摘要： The new generation Elastic Optical Networks (EONs) based on Orthogonal Frequency Division Multiplexing (OFDM) can accommodate exponentially increasing heterogeneous data traffic efficiently and economically. In EONs, the optimum channel spacing between various subcarriers is very crucial for its efficient performance. The use of Sub-Carrier Multiplexing (SCM) in EONs is visualized as an evolving field. This paper present the evaluation of SCM based EONs for both mathematical and simulative model. The designed SCM-EON network is analytically evaluated for its performance with different modulation techniques (Direct Modulation and External Modulation). The performance of system is also evaluated for amplification using Semiconductor Optical Amplifier (SOA) and Erbium Doped Fiber Amplifier (EDFA). Simulative results show that Optical Phase Modulation (OPM) along with EDFA offers enhanced performance for the proposed model. It has also been observed that OPM is a better technique for SCM and hence it can be deduced that the combination will boost EONs efficiency in handling network resources.
关键词： SCM,Elastic Optical Networks,OFDM,EDFA,OPM,Bandwidth variable-wavelength cross-connects (BV-WXC),Quadrature Amplitude Modulation (QAM),Coherent Optical Orthogonal Frequency Division Multiplexing (CO-OFDM),Mach-Zehnder modulator (MZM)
更新于2025-09-23 15:23:52
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Enhanced performance of odd order square geometrical shaping QAM constellation in underwater and free space VLC system
摘要： Visible light communication(VLC) employing light-emitting diodes(LED) as light source has become a promising field for underwater wireless communication. However, due to the complex underwater environment and scattering, absorption and diffusion effects during optical transmission in water, the underwater VLC system will suffer from poor SNR and highly nonlinear distortion. In this paper, we proposed and experimentally demonstrated a novel Square Geometrical Shaping(SGS) odd order QAM discrete multitone(DMT) and carrier-less amplitude phase(CAP) modulation based VLC system. Unlike to traditional odd order QAM constellation aiming at the minimum Euclidean distance but without Gray coding at edge constellation points, the new SGS constellation boasts acceptable Euclidean distance and thoroughly Gray coding for every constellation point. Therefore, the system performance can be effectively enhanced by SGS constellation for low SNR and high nonlinearity cases. Both numerical and experimental results verify that SGS 32QAM and 128QAM constellations can outperform traditional QAM constellation by mitigating nonlinearity in a blue LED based underwater and free space VLC system using DMT modulation or CAP modulation. By employing SGS 128QAM, we successfully demonstrate 2.534Gb/s 1.2meter underwater transmission at the driving voltage of 1.1Vpp.
关键词： SGS constellation,nonlinearity,CAP,VLC underwater system,QAM-DMT
更新于2025-09-23 15:23:52
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[IEEE 2018 International Conference on Information and Communication Technology Convergence (ICTC) - Jeju (2018.10.17-2018.10.19)] 2018 International Conference on Information and Communication Technology Convergence (ICTC) - Polar Modulation with CR Method for Optical Wireless Communication MIMO System
摘要： Simple modulation technique named polar modulation for converting QAM symbol to real and positive symbol is well known that the does not require the complicated process like Hermitian symmetry. However, there is a problem that the Euclidean distance between polar modulated symbols is uneven in constellation, thereby increasing the error probability of a specific symbol. In this paper, we propose an efficient polar modulation scheme which uses CR to uniform the Euclidean distance between polar modulated symbol. Simulation result shows that the proposed method has better BER gain and power consumption compared with general polar modulation.
关键词： QAM,MIMO,QCM,OWC,polar modulation,CR
更新于2025-09-23 15:23:52
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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) - Enhanced Capacity of Radio over Fiber Links Using Polarization Multiplexed Signal Transmission
摘要： The future vision of integrating back- and front-haul in 5G mobile networks requires the design of high capacity transport architectures. To achieve this progress we suggest the application of the radio over fiber (RoF) technology for 5G back- and front-haul access links. Our proposed design is based on the coherent polarization multiplexed (Pol-Mux) technique. To understand the properties of polarization mode dispersion (PMD) we present the impact of PMD on the link quality factor with varying fiber length, bit rate, and PMD coefficient. To increase the capacity of the radio over fiber link we propose a new conversion method utilizing polarization controllers and the polarization beam combiners. Applying the new method 40 Gbit/s QPSK and 16-QAM signals are converted to coherent polarization multiplexed (Pol-Mux) signals. In the Pol-Mux approach the polarization cross talk can cause a significant impairment. However, with sufficient polarization extinction ratio this effect can be reduced substantially. Our simulation results reveal that the Pol-Mux approach yields better performance e.g. in terms of high data rates, and this way can significantly increase the link capacity for 5G access and core network functions.
关键词： QPSK,PMD,Pol-Mux,16-QAM,5G mobile network
更新于2025-09-23 15:22:29
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Precompensation and System Parameters Estimation for Low-Cost Nonlinear Tera-Hertz Transmitters in the Presence of I/Q Imbalance
摘要： Tera-Hertz (THz) transmission can offer several attractive applications, yet developing low-cost energy-efficient THz devices is at an early stage. The most promising low-cost THz transmitter architecture in the literature is the so-called frequency-multiplier-last architecture. However, it is incapable of transmitting quadrature amplitude modulation (QAM) due to the architecture's inherent nonlinear distortions. We study such nonlinear THz communication systems by incorporating the nonlinearity aspects of the low-cost THz devices and the inphase and quadrature (I/Q) imbalance effect into the signal model. Then, we propose a precompensation scheme to compensate the nonlinearity and I/Q imbalance effects, thus enabling the QAM-capable frequency-multiplier-last architecture for THz systems. The proposed precompensation scheme requires the knowledge of the system parameters. To estimate the system parameters, we propose a maximum-likelihood estimator and its practical implementation via an alternating estimation algorithm. We also derive closed-form expressions for the Cramér–Rao lower bounds (CRLBs) of the system parameters estimation, and design the pilot sequence used in estimating the system parameters. Numerical results show that the proposed precompensation schemes overcome the prominent problems experienced in the existing THz systems, namely severe nonlinear distortions of the modulation symbols as well as spectral spreading and/or large spectrum sidelobes, and mitigate the I/Q imbalance effect.
关键词： precompensation,estimation,QAM,I/Q imbalance,nonlinear distortion,Low-cost,Tera-Hertz
更新于2025-09-23 15:22:29
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[IEEE 2018 International Conference on Information and Communication Technology Convergence (ICTC) - Jeju (2018.10.17-2018.10.19)] 2018 International Conference on Information and Communication Technology Convergence (ICTC) - Performance of SIM/S-QAM FSO Systems with Phase Errors in Gamma-Gamma Turbulence Channels
摘要： In this paper, we study the performance of subcarrier intensity modulation (SIM) squared quadrature-amplitude modulation (S-QAM) free-space optical (FSO) communication systems considering the atmospheric turbulence-induced phase error in fading channel. The atmospheric fading channel is modeled by Gamma-Gamma distribution while the Tikhonov model is used for the turbulence-induced phase error. The numerical results quantitatively show the impact of atmospheric turbulence parameters to the performance of FSO systems in terms of average symbol-error probability (ASEP) and the power penalty. Besides, the theoretical results are validated through Monte Carlo simulation to confirm our analysis.
关键词： Free-space optics (FSO),Phase error.,Atmospheric Turbulence,Fading Channel,Squared quadrature-amplitude modulation (QAM)
更新于2025-09-23 15:22:29
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Construction of Zero Correlation Zone Sequence Sets over the 16-QAM Constellation
摘要： Based on the known binary and quaternary zero correlation zone (ZCZ) sequence sets, a class of 16-QAM sequence sets with ZCZ is presented, where the term “QAM sequence” means the sequence over the quadrature amplitude modulation (QAM) constellation. The sequence sets obtained by this method achieve an expansion in the number of 16-QAM sequence sets with ZCZ. The proposed sequence sets can be applied to quasi-synchronous code division multiple access (QS-CDMA) systems to eliminate the multiple access interference (MAI) and multipath interference (MPI) and improve the transmission data rate (TDR).
关键词： zero correlation zone (ZCZ),QS-CDMA,16-QAM sequence,filtering operation
更新于2025-09-23 15:21:01
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Performance studies of MIMO based DCO-OFDM in underwater wireless optical communication systems
摘要： The research in underwater communication system is focused towards wireless networks in view of recent developments in wireless technology and increasing need for deep sea data mining. The underwater wireless optical communication (UWOC) have more advantages for short-range wireless links due to very high bandwidth and data rate than acoustic communication. Although UWOC offers high capacity links at low latencies, they suffer from limited communication range due to various distinctive characteristics of underwater channel. A major degrading effect associated with the underwater channel is turbulence-induced fading. To mitigate this fading and to extend the viable communication range, spatial multipath diversity techniques can be adopted over UWOC links. The proposed work evaluates the performance of a multicarrier modulation scheme, i.e., MIMO based DC biased Optical Orthogonal Frequency Division Multiplexing (DCO-OFDM) for underwater wireless optical channel. The simulation of MIMO-DC biased optical OFDM technique employing spatial diversity in underwater optical communication is a novel approach towards the determination of an optimal modulation technique for underwater optical wireless channels. The performance is evaluated based on the various parameters such as Signal to Interference plus Noise Ratio (SINR), Throughput and Bit Error Rate (BER). A simple experiment is conducted to demonstrate the BER performance assessment for different link distance of 0.45 m and 1.5 m with different transmitter and receiver configurations (SIMO and MIMO) for both clear water and coastal water using MIMO DCO OFDM technique.
关键词： SNR,BER,MIMO,DCO-OFDM,QAM,Underwater wireless optical communication
更新于2025-09-23 15:19:57
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[IEEE 2018 IEEE BiCMOS and Compound Semiconductor Integrated Circuits and Technology Symposium (BCICTS) - San Diego, CA, USA (2018.10.15-2018.10.17)] 2018 IEEE BiCMOS and Compound Semiconductor Integrated Circuits and Technology Symposium (BCICTS) - A DC-60 GHz I/Q Modulator in 45 nm SOI CMOS for Ultra-Wideband 5G Radios
摘要： This paper presents a DC-60 GHz I/Q modulator/transmitter chip in 45 nm SOI CMOS, that can serve as a critical building block for next generation multi-standard and high-capacity wireless backhaul links. The modulator consists of a wideband quadrature signal generator, wideband buffers and two current-combined DC-100 GHz low-noise double-balanced mixers driven in quadrature. The 1.4 mm2 modulator chip achieves 60 dB of dynamic range in a 1 GHz bandwidth, with an OP 1dB of -10 to -12 dBm, thus enabling spectrally-ef?cient high-order modulation schemes such as 256-QAM. The I/Q modulator achieves 200 Gbps in 16-QAM (50 Gbaud/s), while consuming 200 mW, resulting in record 1 pJ/bit modulation ef?ciency. In addition to backhaul links, the modulator is an attractive and cost-effective alternative to short-range optical links for data center interconnects (DCI) applications.
关键词： QAM,CMOS,transmitter,5G,mm-wave,radio,Modulator
更新于2025-09-23 15:19:57
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[IEEE 2018 26th Telecommunications Forum (TELFOR) - Belgrade, Serbia (2018.11.20-2018.11.21)] 2018 26th Telecommunications Forum (TELFOR) - Adaptable QAM Transmitter to Current Elastic Optical Networks Demand
摘要： A novel adaptable transmitter scheme for optical networks (ONs) is proposed supporting the generation of arbitrary higher-order quadrature amplitude modulation (QAM) formats currently used in worldwide installed networks. With this transmitter structure, a low cost actual network upgrade towards flexible elastic future-proof ONs is allowed.
关键词： Transmitter,Elastic Network,QAM,Modulation Format,Optical Network
更新于2025-09-19 17:15:36