Search

Wireless Network-on-Chip (WNoC) incorporating on-chipantennas has emerged as a promising alternative to overcome the communication bottleneck due to high frequency operation, propagation delay, crosstalk delay, noise and need for repeaters inwired interconnects in chip-multiprocessors (CMPs). Recent advancements in nano materials, such as graphene have enabled the development of novel plasmonic graphene devices, which intrinsically operate in THz band. This ultra-low power andcompact graphene-based nano-antennas (GNA) establishes ultra-high bandwidth THz-on-chip wireless links for intra/inter-chip communication. In this article, we design and simulate a novel fork-shaped planarplasmonic nano-patch antenna using grapheneon SiO2/Si substrate that can be integrated into transceivers working at THz frequencies operating from 0.5 THz to 2.6 THz. By simulation at THz band, proposed antenna performance as a wireless inter/intra-chip link is investigated by numericallyobtaining itssignal transmission coefficient characteristics between the two on-chip antennas, acting as transmitter and receiver or vice-verse for short-range THz communication among wireless NoC based multi-core processors integrated on same substrate. Theresults are obtained by placing the antennas in broadside orientation, that can communicate with intra-chip transmission coefficients ranging from − 20 dB to − 60 dB while sustaining bandwidths upto 0.13–0.2 THz. Further, the effect of transmission and radiation performance of proposed antennas with increase in distance dlink is studied along with reconfigurable nature of graphene with varying chemical potentials from 0.1 eV − 0.5 eV. Proposed antenna has obtained maximum gain and radiation efficiency of 3.89 dB and 58% at 1.83 THz when chemical potential of 0.1 eV is applied. This concept can broadly be applied to future systems as it can be directly integrated into transceivers as graphene is compatible with CMOS processes.Fabrication process steps of proposed on-chip antenna and its feasibility as a real device in chip environment isalso discussed. [ABSTRACT FROM AUTHOR]

A scheme for the compensation of chromatic dispersion in Radio over Fiber systems with enhanced performance is proposed and demonstrated. The system implements a cascade of an Ideal Dispersion Compensation Filter and a tanh apodized, linearly chirped Fiber Bragg Grating for mitigating the degradation caused by chromatic dispersion. The analysis probes variations in transmission distance and channel spacing while investigating vital performance parameters like the Q factor and Bit Error Rate. Two-channel spacings of 100 GHz and 50 GHz, transmission distances ranging between 70 and 120 km and effective refractive index of the apodized and linearly chirped FBG extending between 1.3 and 1.5 are considered for the study. The analysis also covers the analysis of optical signal to noise ratio as the fiber length is varied. Additionally, the system performance is evaluated when the transmitted power of the continuous wave Laser in the transmitter segment is altered. The simulation results demonstrate that the system provides acceptable Q factor and BER values even at a transmission distance of 120 km. The comparative analysis with the formerly published results validates the performance enhancement achieved by the proposed system. [ABSTRACT FROM AUTHOR]

The performance of free space optical (FSO) communication is primarily dependent on atmospheric turbulence and pointing errors, where pointing error compromises of boresight error and jitter. However, most of the existing work considered pointing error by counting zero-boresight error or jitter while evaluating the performance of FSO communications. In this paper, a generalized distribution, Nakagami-m fading, for the radial displacement of pointing error is considered by taking account of both boresight and jitter error for performance analysis of FSO communication. Two subsequent auto-tracking mechanisms are designed and developed at the transmitter to combat the issues of boresight error and jitter. First is a coarse tracking system to minimize the boresight error and second is fine tracking to remove leftover boresight error known as jitter. FSO received power is continuously monitored, and the link status is feedback to the transmitter via the RF link to initiate the corresponding tracking. The proposed auto-tracking mechanism has experimented with a wide range of non-zero boresight angles, which is from ± 10 ∘ to ± 180 ∘ with a fine-tuning of horizontal displacement up to ± 8 cm from the receiver center. A closed-form outage probability is derived over generalized phenomenon where the analytical results are compared with simulation, measurement, and with existing methods. [ABSTRACT FROM AUTHOR]

Mode division multiplexing (MDM) has emerged as a futuristic and potential technology for next-generation optical wireless networks. However, the inter-channel interference in multi-channel systems and the modes coupling in mode division multiplexed systems are the two predominant limitations and need to be addressed. Therefore, in this work, an inter-channel interference suppression technique based on the opting transmitter diversity (TD) technique is presented in 2λ × 2HG modes × 10 Gbps IsOWC system. For the realization of TD technique, two diverse arrangements such as Non return to zero (NRZ)-return to zero, and NRZ-alternate mark inversion (AMI) are proposed and also compared with non-TD arrangement such as NRZ–NRZ over 5000 km IsOWC distance. Hermite Gaussian (HG) modes like HG00 and HG01 are modulated with 850 nm and 850.8 nm each and provide 40 Gbps capacity. The proposed multichannel MDM-TD-IsOWC system is investigated for different IsOWC distances and pointing errors in terms of Log Bit error rate (BER) and compared with different reported studies. It is observed that IsOWC system provide improved performance by incorporating an N–A (NRZ-AMI) arrangement and offer maximum log BER for N–N (NRZ–NRZ) (non-TD) system. [ABSTRACT FROM AUTHOR]

Four-Wave Mixing (FWM) is a performance constraint in WDM Radio over Fiber(RoF) systems. This article uses several equations to analyze & investigate the performance of FWM crosstalk power and Signal to Crosstalk Ratio (SXR) corresponding to channel spacing, transmission distance & input optical power for different kinds of fiber like Alcatel Teralight, Corning Leaf, Furukawa SM-332 and Lucent Truewave under the influence of higher-order dispersion terms up to 10th order. An improved optical network including a polarization rotator at the transmitter and modern state of art optical fibers is proposed to combat FWM-induced crosstalk. It is reported that the use of a polarization rotator reduces FWM crosstalk by 7.5 dBm with an input power of 20 dBm. Further, it is also revealed that Corning LEAF performs better compared to the rest of fibers while minimizing FWM-induced crosstalk. [ABSTRACT FROM AUTHOR]

Underwater visible light communication emerges as a promising technique to enhance the capacity of underwater wireless communication networks for upcoming generation. Major technical problem with underwater visible light communication systems in motion is the pointing, acquisition, and tracking. To ease pointing, acquisition, and tracking, hence it is important to navigate optical information beam over broad range and adjust the transmitter beam divergence angle according to the link condition, which is adjusted by the Optisystem software. In this paper, performance comparison among wide range of transmittance optical beams in underwater visible light communications system for high-speed communication is presented for PIN as well as for Avalanche photodiode. The effect of using variable transmittance beam-divergence angle on the bit-error rate, signal-to-noise ratio, communication link distance is also investigated. OptiSystem and MATLAB software is used to implement the underwater visible light communication transceiver system. Finally, it is shown in the paper that in the presence of pointing errors, adaptive beam control techniques improve the performance of high-speed Underwater visible light communication system. [ABSTRACT FROM AUTHOR]

For several years, the fields of new technologies have been experiencing a real boom. The use of the terahertz band is an appropriate solution to meet the requirements of these technology. However, this technology has special requirements among which its antennas must have high bandwidth of few THz and achieve high gain for high productivity. In this paper, we will focus on the design and analysis of an antenna for THz technology. The antenna structure proposed in this work has better performance in terms of bandwidth and gain. In fact, multiples slots were added to the antenna to enhance the antenna's bandwidth. In addition, to enhance the antenna performance in terms of gain and protect the antenna feed line against environmental jeopardies a thin layer as superstrate is used. The suggested antenna covers a wide −10 dB bandwidth from 0.9 to 17.3 THz with a peak gain of 12.8 dBi. Moreover, a VSWR less than 2 at the operating band is obtained. Furthermore, the suggested antenna has circular polarized radiations with an axial ration (AR) less than 3 dB over a wide band 13.6–17.3 THz which mean that the proposed antenna is well suited for application where the transmitter and receiver are moving which is the most case for wireless system. Thus, the suggested THz antenna could be a successful choice for terahertz application like future high-speed short-range indoor wireless communication, explosive detections, arms detection, medical imaging, pharmaceutical analysis, and material characterization in the THz regime industrial inspections. [ABSTRACT FROM AUTHOR]

Super-PON is a 16-wavelength passive optical network with 50 km reach and 64 ONUs per λ , providing up to 10 Gb/s to sparsely populated areas. To bridge its challenging loss-budget, Super-PON includes an EDFA located next to the OLT, thus compromising transceiver integration and future spectral expansion. An alternative for downstream transmission consists in using a powerful directly-modulated semiconductor optical amplifier (SOA) and an avalanche photodiode. Here, we numerically demonstrate the technical feasibility of this proposal. By combining a sensitivity of − 24.9 dBm and an optimized SOA transmitter output of +19.4 dBm, error-free (BER ≤ 3.8x10 - 3 ) transmission is demonstrated. This achievement relies on the use of PAM-4 modulation to combat the limited opto-electronic bandwidth of the SOA, and Tomlinson-Harashima precoding (THP) to mitigate fiber transmission and receiver impairments. It is also shown that THP enhances the direct modulation capability of SOAs, leveraging their use in integrated transceivers aimed for high-loss photonic systems. [ABSTRACT FROM AUTHOR]

Dual polarization quadrature phase-shifting keying (DP-QPSK) wavelength division multiplexing (WDM) systems are currently acting as the backbone of long-haul optical networks. It has provided a cost-effective solution for network up-gradation due to its backward compatibility on legacy infrastructure of standard single-mode fiber. Encoding of two bits per symbol per polarization, low BER over long haul transmission reach, and simple digital equalization techniques are the main features of 100G DP-QPSK technology. A large amount of voice, video, and high-speed data services are being provided by DP-QPSK WDM-based optical networks. This paper reviews the progress happened in the DP-QPSK WDM system since its introduction. The work is focused on reviewing important incorporations researched and developed related to the transmitter and digital coherent receiver. [ABSTRACT FROM AUTHOR]

We present an emulation design method for converting asymmetrical transmitters to nonreciprocal isolators equipped with time-varying metasurfaces. To illustrate the model, we design a structure using a combination of the photonic crystal (PhC) and time-varying metasurface. Moreover, we propose a general approach for numerical analysis of the time-modulated proposed structure using the extension of the transfer matrix method (TMM) which consists of working through the device one layer at a time and calculating an overall transfer matrix including the time-variation of the permittivity and permeability in each layer. Also, we use an optimization algorithm that is less used in the field of electromagnetism but is suitable for fast and accurate parameter optimization. The results show that the proposed method, using pure time-varying metasurfaces which cannot prepare full nonreciprocity alone, is a promising procedure for breaking the Lorentz reciprocity in the general isolator system as well as maintaining the main core of previously asymmetric designed structure. [ABSTRACT FROM AUTHOR]

Free space optical (FSO) communication is a remarkable transmission technique and offers many benefits such as faster rate of data transfer, immunity to electromagnetic interferences (EMI), security and enormous bandwidth. In this research article, a spectrum sliced (SS) FSO system at 2.5 Gbps is demonstrated by using Supercontinuum generation in highly nonlinear fiber for spectrum broadening. Modulations plays crucial role in the final performance of FSO system and therefore, differential phase shift keying (DPSK) based SS-FSO system is investigated at different FSO distances, beam divergences, transmitter and receiver antenna diameters in terms of Q factor and log BER. Further, in order to evaluate the performance of proposed systems, it is compared with non-return to zero (NRZ), return to zero (RZ) and compressed spectrum RZ (CS-RZ). Result revealed that proposed DPSK-SS-FSO system surpassed the performance of rest of investigated modulations formats. [ABSTRACT FROM AUTHOR]

Free space optics (FSO) communication is a very recent mechanism. It is mainly needed when physical connection between the transmitter and the receiver is practically impossible and when high bandwidth data transmission is expected. This paper walks through the investigation of the performance of FSO communication adopting spectral amplitude coding optical code division multiple access (SAC-OCDMA) systems at different weather scenarios. The suggested system uses enhanced double weight codes as signature codes by 3 clients, simultaneously. To eliminate multiple access interference and phase induced intensity noise, two different detection schemes are used; single photodiode (SPD) and modified-AND subtraction detection schemes. Furthermore, a comparison between PIN and APD detectors is performed. The performance is evaluated through its propagation distance, received power, Q-factor and bit error rate (BER). The obtained numerical results reveal both Q-factor and BER are modified by 30%. Accordingly, the system performance is enhanced by 30%, when using SAC-OCDMA-FSO with SPD detection technique compared with modified-AND subtraction technique. [ABSTRACT FROM AUTHOR]

The rapid increase in internet services demands high capacity and brings high energy dissipation. For broadband access networks, energy efficient passive optical networks (PONs) are ubiquitously demonstrated to conserve energy. However, high cost components for monitoring, complexity, delays and synchronization issues in active/passive optical network unit (ONU) status are the utmost issues to be addressed. Energy efficient symmetrical Wavelength division multiplexed (WDM) and Time division multiplexed (TDM) hybrid passive optical network using Access-Load Difference between ONUs (ALD) approaches with dynamic wavelength switches has been proposed. Dual capacity providing system is presented where 2 Gbps and 12 Gbps sources are operated according to traffic at ONUs. Total capacity of individual low data rate transmitter are 8 Gbps (2 Gbps × 4) and 48 Gbps (12 Gbps × 4) for each ODN serving 64 ONU. Proposed approach is competent to only use specific transmitter module based on load at ONU and keep rest of the transmitters inactive. Design of ALD DWS is such that there is no service interruption even when any transmitter stops working. Moreover, nonlinear carrier generation eliminate the requirements of lasers for upstream transmission which saves cost as well as energy. It is observed that proposed system save 400% energy below 10 Gbps, 300% between 10–20 Gbps, 200% between 20–30 Gbps, 100% between 30–40 Gbps and 0% for beyond 50 Gbps. Therefore variable transmitters (Bandwidth) are operational in this architecture and provide economical in initial operational expenditure (OPEX). [ABSTRACT FROM AUTHOR]

A scheme for transportation of information with minimum Rayleigh backscattering (RB) noise to the multi-users by employing Qdash laser diode as a source is designed and evaluated. In this paper, employing digital phase shift keying, millimeter wave, 16-quadrature amplitude modulation orthogonal frequency division multiplexing (16-QAM OFDM), and 32-QAM OFDM techniques, the data rates of 4 × 10 Gbps are transmitted simultaneously over 50 km single mode fiber, plus 15 m wireless link, 50 m free space optical (FSO) link, 10 m wireless respectively. Four selective self-injection locked modes of Qdash laser are utilized as optical carriers for downstream and upstream transmission. To ensure the matter of mitigation of RB noise, which mainly arises due to the transmission of light-wave of same wavelengths in bidirectional transportation, the carrier signals of different wavelength are used for modulation and remodulation in optical line terminal and optical network unit. Besides being a strong support to increase the tolerance level against RB noise, this architecture is capable to transmit less noisy information wirelessly in radio frequency sensitive areas too. The constancy of the proposed architecture is evaluated by very low power penalty (~ 1.5–1.7 dB, ~ 2.4–2.6 dB, ~ 1.4–1.6 dB, ~ 1.7–1.8 dB for four channels respectively), clear constellation, prominent eye opening, low bit-error-rate (< 10–9 for pseudo random bit sequence data stream and < 3.8 × 10–3 for OFDM signal) and low error vector magnitude (< 12.4% for 16 QAM, < 10% for 32 QAM). Therefore, the proposed architecture could be promising alternative not only due to the scheme for mitigation of RB noise but also be a potent in the field of applications of the communication world to provide less noisy information to the multi-users (wired/wireless/FSO). [ABSTRACT FROM AUTHOR]

As a potential complementary access technology for the 5G wireless systems, optical wireless communication (OWC) gains extensive attention for decades owing to its numerous advantages of broad license-free spectrum, immunity to electromagnetic interference and high-level privacy. However, two rigorous obstacles to achieve high data-rate OWC transmission are the severe nonlinear clipping of transmitter and high-frequency attenuation of OWC system. In this paper, we propose the first interleaved single-carrier frequency-division multiplexing (I-SC-FDM) scheme for OWC systems. Compared with orthogonal frequency-division multiplexing (OFDM), I-SC-FDM has a lower peak-to-average power ratio, which makes it more immune to the nonlinearity clipping in OWC systems. Meanwhile, for the bandwidth-limited OWC systems, I-SC-FDM has better performance on resistance to the serious high-frequency distortion. The simulation results indicate that, under the transmitter nonlinearity and optical-wireless diffuse fading channel, the maximum Q2 of I-SC-FDM is about 3.44 dB and 3.14 dB higher than that of OFDM when 4-ary quadrature amplitude modulation (4-QAM) and 16-QAM are modulated, respectively. The results show the feasibility and advantages of I-SC-FDM for cost-sensitive OWC systems. [ABSTRACT FROM AUTHOR]