Fiber Access Research Articles

Techno‐economic model of fibre‐to‐the‐home as 5G fronthaul: evaluation of capital expenditures

Fibre optics is the best solution for the deployment of 5G fronthaul, but it is expensive and time-consuming. The use of a common fibre access network for fixed and mobile services results in cost reduction, quality of experience improvement, and synergy and convergence of the resources. Accordingly, in this study, a practical dual-purpose techno-economic model (FTTx + 5G) was introduced to evaluate its Capital Expenditures (CAPEX). Some technical, financial, and geographical data were also used for computation and comparing the costs in different situations by the integer linear programming method.

A Review on MIMO Wireless Signals over Fibre for Next Generation Fibre Wireless (FiWi) Broadband Networks

Next-generation access/mobile networks have set high standards in terms of providing wireless services at high data rates in order to keep up with the vast demands for other mobility and multiple services. Wireless-optical broadband access network (WOBAN) technology, also known as fibre-wireless (FiWi), has uncovered incredible opportunities for the future of next-generation networks because it gets the best of both domains: huge bandwidth provided by the optical fibre and high ubiquity of the wireless domain. The objective of FiWi networks is to integrate the high data rate and long reach provided by optical networks and the ubiquity and mobility of wireless networks, with the target to decrease their expense and complexity. Multiple-input–multiple-output (MIMO) is an inevitable technique for most of the new mobile/wireless networks that are driven by the huge data rates required by today’s users. Consequently, to construct any FiWi system for next-generation (NG) access/broadband networks, an MIMO technique has to be considered. This article presents a comprehensive, contemporary review of the latest subsystems, architectures and integrated technologies of MIMO wireless signals backhauling using optical fibre or fibre access networks, such as passive optical networks (PONs). An overview for FiWi, PONs and MIMO wireless systems is provided. In addition, advanced techniques of accommodating the MIMO wireless signals over optical fibre are explained and compared. Different types of wireless MIMO signals over fibre, such as 5G, WiFi and related transport technologies, are reviewed. Moreover, future research trends are also discussed.

Integrating phosphotungstic acid-assisted prerefining with cellulase treatment for enhancing the reactivity of kraft-based dissolving pulp

Viscosity control and reactivity enhancement are of practical importance for high-quality dissolving pulp manufacturing. In this work, we demonstrate a two-step activating process consisting of a phosphotungstic acid (PTA)-assisted prerefining (PTA/R pretreatment), followed by cellulase treatment for this purpose. The cellulase adsorption can increase from 29.1% to 49.7% as a result of PTA/R pretreatment (8000 r at 90 °C). The viscosity of the resultant pulp decreases from 665 to 430 mL/g, while its Fock reactivity increases from 31.5% to 74.4% under a low-loading cellulase treatment (0.5 mg cellulase /g odp), which mainly due to the fact that the PTA/R pretreatment can increase fiber accessibility and viscosity control, thus facilitating cellulase adsorption and reaction efficiency. Moreover, PTA also shows a high recyclability/ reusability (more than 86%) during the PTA/R pretreatment. Therefore, the new proposed two-step activating process provides a green, and efficient pathway for large-scale manufacturing of high-quality dissolving pulp.

Key Enabling Technologies for the Post-5G Era: Fully Adaptive, All-Spectra Coordinated Radio Access Network with Function Decoupling

With the rapidly growing bandwidth demand for wireless applications, new system technologies related to post-5G are emerging. In this article, an all-spectra fully adaptive and coordinated radio access network (RAN) is reported and discussed. By employing a fiber-wireless integration and networking architecture, all data-carrying channels could be aggregated in the same fiber access infrastructure. This enables a coordinated RAN with function decoupling, in which lower RF, 5G New Radio (NR), sub-THz, and even lightwave are employed; also, different types of services are delivered depending on their physical layer properties. Promising scenarios are discussed, such as integrated access of wireless NR-free space optical (FSO) backhauling and indoor systems via visible light communication (VLC) and efficient NR beamforming aided by VLC positioning system. The former use case can enhance the network throughput and reliability. This is because both FSO and NR can support high channel capacity due to their abundant bandwidth. Meanwhile, with the advancement of novel DSP techniques, the stability of the NR-FSO link under diverse weather turbulences or suffering from burst mode interference can be enhanced. The latter scenario provides an alternative solution for high-speed data link and a simplified beam management via the VLC-aided positioning system. VLC can concurrently provide ubiquitous indoor illumination, data transmission, and positioning. With the help of artificial intelligence algorithms, a VLC-based precision positioning system can provide a location accuracy of less than 1 cm, and it is able to meet the narrow beam size of the NR beamformer in a 3D model. Therefore, it is foreseeable that an all-spectra function decoupled RAN can serve as a unified network platform to support all wireless applications while optimizing system throughput, channel condition, network coverage, and software/ hardware complexity for post-5G mobile data networks.

Swelling and dissolution kinetics of natural and man-made cellulose fibers in solvent power tuned ionic liquid

The kinetics of the dissolution and swelling of different cellulose fibers in the ionic liquid 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]) was studied by varying solvent power and temperature. Natural fiber, flax, and man-made fibers, Cordenka and Lyocell-type (Ioncell) were used with one Ioncell fiber containing lignin and hemicelluloses. Through the addition of water, the solvent power was modified from very good (neat ionic liquid), to moderate (with 5 wt% water) and weak (15 wt% water). The temperature was varied to correlate the fiber dissolution rate with the solvent viscosity. All fibers were characterized by chemical composition, crystallinity, molecular weight distribution and dynamic vapor sorption. It was demonstrated that while the rate of fiber dissolution in neat ionic liquid depends on fiber accessibility and solvent viscosity, the water-induced decreased solvent power dominates the general fiber behavior. Flax appeared to be the most “sensitive” to the solvent power due to its hierarchical structure. The fastest dissolution or swelling was recorded for Ioncell and the slowest for Cordenka.

Sensory quality of tilapia hamburger (oreochromis niloticus) with addition of soybean residue (okara)

This paper intends to develop and evaluate the sensory quality of tilapia hamburgers with addition of okara flour, aiming to develop a product of good protein quality, rich in fiber, low cost and easy access to the population. Okara flour was added at different concentrations (0, 5, 10, 15, 20 and 25%) to hamburgers and then these were subjected to analysis of acceptability (9-point hedonic scale). The averages for all evaluated parameters varied between 5.02 and 7.5, within the range of "indifferent" to "liked moderately". The highest means were found for formulations with 10 and 15% of okara, indicating the okara amount that provides better sensory quality of the product. These results confirm the tendency to seek products with higher nutritional value, and tilapia hamburger with added okara as an alternative to market, aiming at making fish and soybean increasingly present in the eating habits of the population.

Fiber investment and access under uncertainty: long-term contracts, risk premia, and access options

Regulated access schemes shape incentives for both investment and entry in next-generation networks. We study in a general duopoly setting whether and how risk premia, access options or long-term contracts improve those incentives as compared to standard access pricing. The first two do so: Risk premia guarantee highest coverage, while distorting retail pricing. Access options safeguard undistorted retail competition, but are not effective in the most costly areas. On the other hand, long-term contracts have little scope to increase coverage because they intensify retail competition.

Integration of FSO Traffic in Ring-Topology Bidirectional Fiber Access Network With Fault Protection

In this work, we first propose and demonstrate a bidirectional time-division-multiplexing (TDM) free space optical communication (FSO) traffic integrated in ring-based fiber access network together with fiber fault protection. Here, while we add the new designed optical devices in the central office (CO) and each optical wireless unit (OWU) respectively, the TDM-FSO fiber system can achieve the self-protected operation against fault. In addition, according to the proposed ring-based fiber network, the maximum numbers of eight OWUs can be provided for the symmetric 10 Gbps on-off keying (OOK) FSO downstream and upstream connections. As a result, the proposed FSO access network can allow 25 km fiber transmission and proper FSO transmission length depending on the atmospheric attenuation of different weather condition.

Changes in supramolecular structure and improvement in reactivity of dissolving pulp via enzymatic pretreatment with processive endoglucanase EG1 from Volvaria volvacea

Processive endoglucanase EG1 and its core domain, EG1(CD), were used to pretreat the commercial dissolving pulp to improve cellulose reactivity. The Fock reactivity of the pulp which was treated with EG1 and EG1 (CD) at 50 U/g enzyme loading increased from 74.3% of the control to 90.6% and 88.4%, respectively. Refining also improved the Fock reactivity of the pulp, but not as effective as EG1 or EG1(CD) treatment. Refining prior to EG1 or EG1(CD) treatment could slightly further improve the Fock reactivity, to 91.6% and 90.0%, respectively. After enzymatic treatment and (or) refining, the water retention value, differential scanning calorimetry and alkaline solubility analysis indicated that enzyme treatment, especially by EG1, significantly increased the accessibility of fibers to reaction reagents. Combined with the characteristics of soluble reducing sugar produced by EG1 treatment and the changes of degree of polymerization, it is inferred that a small fraction of cellulose crystallization regions are destroyed in the enzymatic hydrolysis process due to the processive acting ability of EG1, and some microchannels in the fiber cell wall were created, which is similar to the effect of “drilling holes”, so that the reaction reagent can reach the inside of the cell wall evenly, thus obviously improving the reactivity of the dissolved pulp.

Enhancing latency performance through intelligent bandwidth allocation decisions: a survey and comparative study of machine learning techniques

Converged access networks consolidating 5G and beyond and fixed optical fiber access are expected to support future latency-sensitive human-to-machine applications over the Tactile Internet. Making intelligent bandwidth allocation decisions among end users/machines/robots of the converged network is thus crucial to meeting stringent latency requirements. The recent renewed interest in machine learning (ML) has contributed towards a plethora of undeniable performance improvements in communication networks. Current insights into how ML can be exploited to provide intelligent bandwidth allocation decisions to enhance latency performance, along with guidance on the most suitable ML technique in that regard, remain elusive. This paper provides the first insights, to the best of our knowledge, into the suitability of commonly adopted ML techniques for this purpose by first presenting an in-depth survey focusing on the technical details of these techniques and how each technique is used in existing studies. The benefits, drawbacks, resultant time and space complexity incurred, and prediction accuracy are then evaluated for each ML technique reviewed. Next, a comprehensive comparative study of the ML techniques is presented for the first time, to our best knowledge, to provide guidance on the selection of ML technique that provides intelligent bandwidth allocation decisions towards supporting emerging latency-sensitive applications. The uplink latency performance of a converged network adopting an artificial neural network (ANN) supervised bandwidth allocation scheme is then compared with those arising from using existing bandwidth allocation schemes. Results highlight the ability of the ANN to learn the association among bandwidth demand, network parameters, and the resulting uplink latency such that, in operation, the allocated bandwidth will always be optimized to enhance latency performance.

Long-range single-molecule mapping of chromatin accessibility in eukaryotes.

Mapping open chromatin regions has emerged as a widely used tool for identifying active regulatory elements in eukaryotes. However, existing approaches, limited by reliance on DNA fragmentation and short-read sequencing, cannot provide information about large-scale chromatin states or reveal coordination between the states of distal regulatory elements. We have developed a method for profiling the accessibility of individual chromatin fibers, a single-molecule long-read accessible chromatin mapping sequencing assay (SMAC-seq), enabling the simultaneous, high-resolution, single-molecule assessment of chromatin states at multikilobase length scales. Our strategy is based on combining the preferential methylation of open chromatin regions by DNA methyltransferases with low sequence specificity, in this case EcoGII, an N6-methyladenosine (m6A) methyltransferase, and the ability of nanopore sequencing to directly read DNA modifications. We demonstrate that aggregate SMAC-seq signals match bulk-level accessibility measurements, observe single-molecule nucleosome and transcription factor protection footprints, and quantify the correlation between chromatin states of distal genomic elements.

Transcatheter Intra-Arterial Infusion Combined with Interventional Photothermal Therapy for the Treatment of Hepatocellular Carcinoma.

BackgroundPhotothermal therapy (PTT) has great potential application in the treatment of tumors. However, due to the low penetration of near-infrared light (NIR) and the low concentration of nanomaterials in the tumor site, the application of PTT has been limited.PurposeThe objective of this study was to investigate the therapeutic effect of transcatheter intra-arterial infusion of lecithin-modified Bi nanoparticles (Bi-Ln NPs) combined with interventional PTT (IPTT) on hepatocellular carcinoma.MethodsBi-Ln NPs were prepared by emulsifying the hydrophobic Bi nanoparticles and lecithin, and the photothermal conversion and cytotoxicity of Bi-Ln NPs were then measured by infrared imaging and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, respectively. Twenty-four VX2 hepatic carcinoma rabbits were randomly divided into four groups. Rabbits in group A received Bi-Ln NPs by intra-arterial infusion and NIR laser treatment (IA Bi-Ln NPs + Laser), group B received Bi-Ln NPs by intravenous infusion and NIR laser treatment (IV Bi-Ln NPs + Laser), group C received PBS (phosphate buffer saline) via intra-arterial infusion with NIR laser treatment (IA PBS + Laser), group D received PBS via intra-arterial infusion (IA PBS). Transcatheter intra-arterial infusion was conducted by superselective intubation under digital subtraction angiography (DSA) guidance. IPTT was performed by introducing an NIR optical fiber access to the rabbit VX2 hepatic carcinoma under real-time ultrasound guidance. Magnetic resonance imaging (MRI) was performed to evaluate the tumor size. Hematoxylin and eosin (H&E) stain and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) were conducted 7 days after treatment to evaluate the necrosis rate and viability of tumor, respectively.ResultsThe Bi-Ln NPs have the advantages of good biological compatibility and high photothermal conversion efficiency. Minimally invasive transcatheter intra-arterial infusion can markedly increase the concentration of Bi-Ln NPs in tumor tissues. IPTT can contribute to the significant improvement in the photothermal efficiency of Bi-Ln NPs. Compared to other groups, the group of IA Bi-Ln NPs + Laser showed a significantly higher tumor inhibition rate (TIR) of 93.38 ± 19.57%, a higher tumor necrosis rate of 83.12 ± 8.02%, and a higher apoptosis rate of (43.26 ± 10.65%) after treatment.ConclusionTranscatheter intra-arterial infusion combined with interventional PTT (IPTT) is safe and effective in eradicating tumor cells and inhibiting tumor growth and may provide a novel and valuable choice for the treatment of hepatocellular carcinoma in the future.

ITU TWDM-PON module for ns-3

Optical fiber access systems are one of the driving forces behind the success of the Internet. Time- and wavelength-division multiplexing passive optical network (TWDM-PON) is regarded as the key technology for future Internet access networks. In this paper, we propose an ITU TWDM-PON module for the ns-3 network simulator and describe its concept and design specifications. The proposed module is developed based on the XG-PON module for ns-3. It can simulate G.989 standard-compliant data packet transmission in the upstream and downstream directions using multiple wavelength channels. It enables us to evaluate the performance issues that arise with the TWDM-PON development, including various dynamic bandwidth allocation and dynamic wavelength allocation algorithms. The proposed module is expected to become a good platform for studying future access networks composed of TWDM-PON and mobile networks by enabling us to simulate dynamic wavelength and bandwidth allocation.

Performance of 1550 nm VCSEL at 10 Gb/s in G.655 and G.652 SSMF

Vertical cavity surface emitting lasers (VCSELs) are now major optical sources in optical communication and technology. The VCSEL-based transmission systems satisfy the next generation optical fibre access networks requirements such as low output power, low threshold currents, no optical amplification and use of single fibre for signal transmission. High speed and long wavelength 1550 nm VCSEL are attractive candidates for use in short distance transmission system due to its cost effectiveness and low drive currents. The performance of VCSEL, especially with respect to the low output power characteristics, has made significant progress. However, dispersion and attenuation is a major hurdle to VCSELs transmission at bit rate of 10 Gb/s and above. In this study, we experimentally and theoretically evaluate the capability of 1550 nm VCSEL to operate upto 10 Gb/s on G.655 and G.652 fibres. We present VCSEL characterization and BER performance as a function of received power. A 1550 nm VCSEL was directly modulated with 10 Gb/s NRZ PRBS 2⁷-1 and transmitted over 25 km ITU. T G.652 and ITU. T G.655 fibres. Error free transmission (with bit error rate, BER, of 10^-9) over 25 km G.655 single mode fibre (SMF) has been demonstrated. The Q factor was used theoretically to quantify the performance of the VCSEL. The Q factor increased with the increase in the output power at the receiver. High Q factor values of 6 and above were achieved when 1550 nm VCSEL was transmitted over G.655 fibre. These results show the feasibility of long-wavelength VCSELs in the deployment of enhanced optical access networks.

Hybrid WDM FSO Fiber Access Network With Rayleigh Backscattering Noise Mitigation

In the paper, we present and investigate an integrated wavelength-division-multiplexing (WDM) free space optical (FSO) fiber access network for 51 km long-reach connection. Here, the proposed network architecture also can mitigate Rayleigh backscattering (RB) interferometric beat noise. We employ symmetric 4 × 10 Gbit/s on-off keying (OOK) WDM-FSO downstream and upstream wavelengths for demonstration. According to the simulated and experimental results, the free space transmission length of 400 to 940 m can be achieved based on various WDM-FSO downstream signals and their corresponding power budget, when the wavelengths are without optical amplification.

Processing and Characterization of Natural Fiber Reinforced Polymer Composite

Polymer materials synthetic fibers, for example, glass and carbon gives point of interest of high stiffness and strength to weight proportion when compare with conventional construction materials, for example wood, cement and steel. The accessibility of natural fibers and comfort of manufacturing have attempted researchers to try locally accessible inexpensive fibers and do study for their feasibility of strengthening purpose. Accordingly, many researchers do broad study on the properties of polymer matrix composite. The synthetic fiber substituting with the natural fiber for example, jute, sisal, pineapple and bamboo. The natural fiber removed by retting and manual procedures were exposed to soluble base treatment. this study is concerned with the investigation of mechanical properties of Grewia Optiva and jute fiber with epoxy resin matrix-based polymer composites. study investigate the tensile, bending and abrasion behavior of composites material made by grewia optiva and jute into epoxy resin. result shows that the better tensile strength of Grewia optiva fiber composite.

Lignin Reactions and Structural Alternations under Typical Biomass Pretreatment Methods

The utilization of biomass in the production of renewable bioenergy and biomaterials has been a popular topic since the past decades as they are rich in carbohydrates. Most biomasses, such as wood, monocotyledons, and agriculture residues, need to be pretreated before the conversion of carbohydrates in order to break down the recalcitrant cell wall structure and increase the fiber accessibility. To date, a variety of pretreatment methods have been developed that vary from physical to chemical and biological methods. Pretreatment processes affect the cell wall physical structure as well as the chemical structure of the cell wall constituents. Comparing to the studies of the cellulose and hemicelluloses structural changes during pretreatment, such studies on lignin are relatively limited. On the other hand, in order to utilize the part of lignin from biorefinery processes, the understanding of the lignin structural changes during the refining process becomes important. In this study, typical pretreatment methods such as hydrothermal pretreatment, alkaline pretreatment, biodegradation, and oxidative pretreatment are introduced and their corresponding impacts on the lignin structures are reviewed.

Millimeter Wave Integrated Access and Backhaul in 5G: Performance Analysis and Design Insights

With the emergence of integrated access and backhaul (IAB) in the fifth generation (5G) of cellular networks, backhaul is no longer just a passive capacity constraint in cellular network design. In fact, this tight integration of access and backhaul is one of the key ways in which 5G millimeter wave (mm-wave) heterogeneous cellular networks (HetNets) differ from traditional settings where the backhaul network was designed independently from the radio access network (RAN). With the goal of elucidating key design trends for this new paradigm, we develop a stochastic geometry-based analytical framework for a millimeter wave (mm-wave) two-tier HetNet with IAB where only the macro BSs (MBSs) have fiber access to the core network and the small cell BSs (SBSs) are wirelessly backhauled by the MBSs over mm-wave links. For this network, we derive the downlink rate coverage probability for two types of resource allocations at the MBS: 1) integrated resource allocation (IRA): where the total bandwidth (BW) is dynamically split between access and backhaul, and 2) orthogonal resource allocation (ORA): where a static partition is defined for the access and backhaul communications. Our analysis concretely demonstrates that offloading users from the MBSs to SBSs may not provide similar rate improvements in an IAB setting as it would in a HetNet with fiber-backhauled SBS. Our analysis also shows that it is not possible to improve the user rate in an IAB setting by simply densifying the SBSs due to the bottleneck on the rate of wireless backhaul links between MBS and SBS.

Optics-Simplified DSP for 50 Gb/s PON Downstream Transmission using 10 Gb/s Optical Devices

Directly-modulated laser (DML) is widely employed in intensity modulation and direct detection (IMDD) system due to its low cost and high output power. However, the corresponding frequency chirp is regarded as one of the main disadvantages for its application in passive optical networks (PONs). In this paper, we theoretically analyze the frequency response evolution of DML based system under different chirp and dispersion conditions, proving that the system bandwidth can be improved by interactions between negative dispersion and DML chirp. Based on this concept, we experimentally demonstrated downstream 50 Gb/s PAM4 signal transmission over 20 km single-mode fiber (SMF) access based on the 10 Gb/s DML operating at 1310 nm and avalanche photodiode (APD). A dispersion-shifted fiber (DSF) providing −150 ps/nm dispersion at 1310 nm in the optical line terminal (OLT) is used to pre-equalize the frequency response of bandwidth-limited directly modulated signals in the optical domain. Thanks to our proposed dispersion-supported equalization (DSE) technique, the system bandwidth can be improved by 5 GHz. Feed-forward equalization (FFE), decision feedback equalization (DFE) and Volterra filter are employed to evaluate the signal performance improvement, respectively. By evaluating the receiver sensitivity, the DSE combined with FFE scheme shows 2 dB improvement than the complex Volterra algorithm, indicating its potential to reduce the complexity of digital signal processing (DSP) and therefore a lower cost and power consumption in PON.

Meeting the Traffic Requirements of Residential Users in the Next Decade with Current FTTH Standards: How Much? How Long?

Traffic demand in access networks has grown in recent years, and service providers need to upgrade their infrastructure to the latest access standards. While fiber has become the preferred technology of choice in access networks, there are many fibre access technologies available in the market. This poses challenging questions to operators that are not always easy to answer: How to upgrade? What technology and for how long wil it cope with the demands? In this article we model the traffic forecast in access networks for the next decade and analyze possible upgrade scenarios of fibre access networks, concluding which of the NG-PON flavors could better fit the demand.