Packet-optical transport network for future radio infrastructure

The technical advances in wavelength division multiplexing (WDM) techniques has made possible the introduction of optical technology into the path layer of the transport network. Besides the significant improvement in the transmission capacity, WDM technology allows the accomplishment of routing and switching functions directly in the optical domain. Thus Optical Cross-Connects (OXCs) can be realized with a throughput of a few hundreds of Gbit/s, so removing the bottleneck placed by electronic technology. The transport network node can be designed as an OXC interfacing a Digital Cross-Connect (DXC). Multi-Gigabit signals are directly routed in the optical network layer by the OXCs, while the DXCs provide demultiplexing to lower digital hierarchies and routing at the electrical level. The optical path layer can be designed so as to be transparent to the signal transmission format and speed. The aim of this paper is to assess the feasibility of transmitting sub-carrier multiplexed CATV channels in this optical path layer, by analysing the performance of the following transmission path: the CATV channels are generated in a production center, cross a geographical area through a transport network and an optical ring of a regional network, down to the access network and then to the customer.

National Defense Traffic and Transport Networks (NDTTN) is an important research object in transportation engineering and characteristics of its topology lay the foundations for national defense traffic networks programming and logistic management. This paper mainly studies the complexity of traffic and transport networks and related problems. The scale-free behavior of NDTTN is investigated and the example analysis is given. According to the flux restriction and the chain failure in the traffic networks, a traffic and transport networks breakdown model based on the node loads is established so as to validate the robustness of traffic and transport networks. Furthermore, the increase mechanism of traffic and transport networks is deep analyzed, and then a scale-free NDTTN model based on the local better choice is proposed. By simulation, it is proved that the general performance of traffic and transport networks constructed with the new model is optimized.

The evolution beyond 5G towards 6G will accelerate the transformations begun by 5G to deploy new approaches to define delivery services. The network should be accessible anywhere, always-on and with the guarantee performances. This poses new challenges to the transport network that should assure available connectivity among the functions at different levels of granularity. The transport network should be so flexible to guarantee on-demand the connectivity among the processing functions that automatically will be required and, at the same time, should assure extreme performance. Optical network and Dense Wavelength Division Multiplexing technology are relevant candidates to match high bandwidth and low latency, but new challenges are required to assure the suitable cost and size for the wireless access networks. The current optical technology, suitable used in aggregation and long-haul transport network, cannot be simply downsized to be used in the access area, but novel paradigm should be considered for the optics as well. Integrated photonics seems a promising direction to realize low cost and low size optical components for the transport network. Moreover, this technology enables a certain level of remote tunability and reconfiguration of optical equipment that allow to simplify and reduce cost of installation in field and operation of the transport network. In this paper relevant optical components for transport networks are analyzed using the integrated photonics to assess the technology challenges.

The introduction of an optical path layer in the transport network allows the improving of the transport nodes processing capability, through wavelength routing , besides increase in point-to-point transmission capacity granted by wavelength division multiplexing (WDM) technique. A generic node of a transport network could be designed as an optical crossconnect (OXC) interfacing a digital cross-connect (DXC). In this paper we distinguish between low, medium and high degree of modularity, and discuss the modularity for some relevant OXC architectures. Moreover a new highly modular OXC architecture is proposed.

Wavelength division multiplexing (WDM) optical interconnect technology offers an effective solution for addressing the ever-increasing data traffic. Microring modulators (MRMs), owing to their high bandwidth, compact footprint, and inherent wavelength selectivity, have become key building blocks in WDM systems. However, the limited free spectral range (FSR) of MRMs restricts the number of available wavelength channels and the corresponding overall data rate capacity in WDM systems. In this study, we propose an optimized Bezier-bent MRM, in which the device radius is reduced to 3 μm to significantly enhance the FSR. The proposed MRM operates without the need for a DC bias voltage and an RF amplifier, exhibiting a low insertion loss of 0.4 dB, an ultrawide FSR exceeding 4 THz, and a high electro-optic bandwidth of over 110 GHz. Back-to-back (BtB) transmission experiments demonstrate that the modulator supports 400 Gbps PAM-8 data transmission under a driving voltage of only 1 V, satisfying the 7% hard-decision forward error correction (HD-FEC) bit-error-rate (BER) threshold of 3.8 × 10–3. Owing to the compact-radius design, the junction capacitance is substantially reduced, enabling an exceptionally low modulation power consumption of 0.2 fJ/bit. The proposed MRM presents significant potential for dense integration in future optical communication systems.

Designing effective transport networks can be considered as one of the most debated problems in the area of computational intelligence. Some nature-inspired algorithms have shown excellent abilities in the adaptive network construction. In this aspect, a unique creature, called Physarum , has exhibited the computing capacity to optimize protoplasmic networks connecting distributed food sources. This inspires our work to design a Physarum foraging platform for constructing transport networks. Specifically, the traditional Physarum foraging model is adapted to construct transport networks in China. In order to get close to the real scenario, practical data are collected to build the environment of the Physarum foraging model and the structure of real transport networks. Some measurements in the domain of complex networks, such as average path length, network efficiency, topology robustness, and functional robustness, are used for performance comparison. The experimental results demonstrate that Physarum foraging models excel in constructing highly efficient and robust networks, which can be utilized for directing the design of transport networks in the real world.

Data security plays a crucial role in healthcare monitoring systems, since critical patient information is transacted over the Internet, especially through wireless devices, wireless routes such as optical wireless channels, or optical transport networks related to optical fibers. Many hospitals are acquiring their own metro dark fiber networks for collaborating with other institutes as a way to maximize their capacity to meet patient needs, as sharing scarce and expensive assets, such as scanners, allows them to optimize their efficiency. The primary goal of this article is to develop of an attack detection model suitable for healthcare monitoring systems that uses internet protocol (IP) virtual private networks (VPNs) over optical transport networks. To this end, this article presents the vulnerabilities in healthcare monitoring system networks, which employ VPNs over optical transport layer architecture. Furthermore, a multilayer network architecture for closer integration of the IP and optical layers is proposed, and an application for detecting DoS attacks is introduced. The proposed application is a lightweight implementation that could be applied and installed into various remote healthcare control devices with limited processing and memory resources. Finally, an analytical and focused approach correlated to attack detection is proposed, which can also serve as a tutorial oriented towards even nonprofessionals for practical and learning purposes.

Emerging data-driven applications such as graph processing applications are characterized by their excessive memory footprint and abundant parallelism, resulting in high memory bandwidth demand. As the scale of datasets for applications is reaching orders of TBs, performance limitation due to bandwidth demands is a major concern. Traditional on-chip electrical networks fail to meet such high bandwidth demands due to increased energy-per-bit or physical limitations with pin counts. Silicon photonic networks have emerged as a promising alternative to electrical interconnects, owing to their high bandwidth density and low energy-per-bit communication with negligible data-dependent power. Wide-scale adoption of silicon photonics at chip level, however, is hampered by their high sensitivity to process and thermal variations, high laser power due to losses along the network, and power consumption of the electrical-optical conversion. Device-level technological innovations to mitigate these issues are promising, yet they do not consider the system-level implications of the applications running on manycore systems with photonic networks. This work aims to bridge the gap between the system-level attributes of applications with the underlying architectural and device-level characteristics of silicon photonic networks to achieve energy-efficient computing. We particularly focus on graph applications, which involve unstructured yet abundant parallel memory accesses that stress the on-chip communication networks, and develop a cross-layer framework to evaluate 2.5D systems with silicon photonic networks. We demonstrate 38% power savings through system-level management using wavelength selection policies with only 1% loss in system performance and further evaluate architectural design choices on 2.5D systems with photonic networks.

To meet energy-efficient performance demands, the computing industry has moved to parallel computer architectures, such as chip-multi-processors (CMPs), internally interconnected via networks-on-chip (NoC) to meet growing communication needs. Achieving scaling performance as core counts increase to the hundreds in future CMPs, however, will require high performance, yet energy-efficient interconnects. Silicon nanophotonics is a promising replacement for electronic on-chip interconnect due to its high bandwidth and low latency, however, prior techniques have required high static power for the laser and ring thermal tuning. We propose a novel nanophotonic NoC architecture, LumiNOC, optimized for high performance and power-efficiency. This paper makes three primary contributions: a novel, nanophotonic architecture which partitions the network in to subnets for better efficiency; a purely photonic, in-band, distributed arbitration scheme; and a channel sharing arrangement utilizing the same waveguides and wavelengths for arbitration as data transmission. In a 64-node NoC under synthetic traffic, LumiNOC enjoys 50% lower latency at low loads and ~40% higher throughput per Watt on synthetic traffic, versus other reported photonic NoCs. LumiNOC reduces latencies ~40% versus an electrical 2D mesh NoCs on the PARSEC shared-memory, multithreaded benchmark suite.

Hazardous Materials Transportation Network (HMTN) has very tight coupling with Traffic Flow Network of Hazmat Transportation (TFNHT). We build the interdependent system for the two networks. One of them is the HMTN of Zhangjiagang City, another is generated with power-law parameters which is considered as TFNHT. One node from the HMTN is random failed as initial emergency failure. It has an impact on one dependent node from the TFNHT. The dependent node would give traffic pressure on connected nodes from the HMTN. In order to know the stability and robustness of each single network, we propose the Node Failure Rate (NFR) to show the percentage of non-function with iterations going on. The two variables in simulation are different average degrees of the TFNHT and initial failure of one random selecting node which belongs to the set of different degrees. In terms of the basic data and the simulation results, we found that (1) the high average degree of the TFNHT has more impact on the interdependent network than the low average degree of it. It means that high values of average degree can lead interdependent weakness and instability; (2) We suggest that the node of low degree should be considered as the part of hazmat transportation routes, and it reduces as far as possible selecting the nodes of high degree when we design the HMTN for improving the robustness; (3) In the interdependent transportation network, the HMTN is more stability than the connected TFNHT and the two networks have the same NFR rising trend.

The transport of the increasing traffic volume caused by narrow-band and evolving broadband services requires the enhancement of the existing public telecommunication transport network. For this purpose an optical network layer based on optical frequency-division multiplexing (OFDM) with cross-connect and add/drop functionalities will be added to the existing transport network, which is based on synchronous digital hierarchy (SDH) and asynchronous transfer mode (ATM). However, electronic SDH and ATM equipment will still be required in the future.

Evaluation of robustness in underground networks

The fifth generation of mobile networks is planned to be commercially available in a few years. The scope of 5G goes beyond introducing new radio interfaces, and will include new services like low-latency industrial applications, as well as new deployment models such as cooperative cells and densification through small cells. An efficient realization of these new features greatly benefit from tight coordination among radio and transport network resources, something that is missing in current networks. In this article, we first present an overview of the benefits and technical requirements of resource coordination across radio and transport networks in the context of 5G. Then, we discuss how SDN principles can bring programmability to both the transport and radio domains, which in turn enables the design of a hierarchical, modular, and programmable control and orchestration plane across the domains. Finally, we introduce two use cases of SDN-based transport and RAN orchestration, and present an experimental implementation of them in a testbed in our lab, which confirms the feasibility and benefits of the proposed orchestration.

In this paper, we consider the problem of network design for hazardous materials transportation in a road network in an uncertain environment. Assume that the parameters such as transport risks of road sections are uncertain and can be represented by fuzzy numbers. A minimum risk Steiner tree network model is developed for this network design problem and there exists one and only one route between any given origin and destination in the tree network. The objective is to minimize the total risk of the hazardous materials transportation. To solve the tree network model with fuzzy parameters, we provide a fuzzy chance-constrained programming model for it, then convert it to the crisp equivalent, and lastly solve the crisp equivalent model using an off-the-shelf solver. The numerical example shows that different confidence levels lead to different Steiner tree networks and in order to design a robust hazardous materials transportation network, we should take into account the fuzziness of the parameters.

In the developing countries along with formal public transport network (FPTN), informal public transport network (IPTN) also plays an integral role by achieving high public transport ridership. IPTN caters effectively to the user’s expectations and appears to be highly integrated with urban fabric. IPTN either complements or compete with the existing FPTN, even though due credit is not given to IPTN and considered as unlawful entities. Efficiency and robustness of transport network is based on topological structure of network. To summarize which network is more efficient and robust, the study tests the network parameters of formal Public Transport Network and Informal Public Transport Network of Nagpur (India). A topological measure of network structure has tested based on elementary concepts of graph theory. We explore the network structure and their properties. The practical significance of the network parameters was then analysed. In the IPTN the degree of small-worldliness is smaller, as compared to FPTN, indicative of IPTN being more robust as compared to FPTN. This study provides an approach to understand the efficiency of an Informal public transport network in combination with Formal public transport network. The article identifies the importance of Informal public transport network to improve the Complementarity with the formal public transport network. Integrating formal and informal transportation network into a hybrid network has the potential to induce the desired relationships amongst FPTN and IPTN, i.e. competing or complimenting nature to improve the overall efficiency of FPTN.