Mobile Backbone Research Articles

Trends and Challenges in Railway Sustainability: The State of the Art regarding Measures, Strategies, and Assessment Tools

Rail is expected to become the backbone of future mobility in the world as the cleanest and greenest high-volume transport. Rail generates the lowest CO2 emissions and energy consumption when in operation, with respect to the other transportation modes, but during construction and maintenance phases, its environmental impacts are significant and need to be carefully assessed and properly mitigated. This paper, through an extensive analysis of the recent literature, aims to provide a comprehensive framework of trends and challenges in railway sustainability, with particular attention paid to track and related materials and components, maintenance strategies, and methods of assessment of sustainability. The followed approach takes into consideration the lifespan of the track and the related main stages. The results show that: (i) several innovative sustainable materials have been introduced with significant environmental performances and limitations, mainly due to the lack of knowledge of long-term mechanical behavior; (ii) appropriate strategies of maintenance, supported by effective monitoring of the track conditions, can reduce negative effects on the environment and society and contribute to making this transportation mode greener; (iii) many devices for the automated detection of the track defects allow increasingly widespread and effective monitoring of the track and are essential means in overcoming the challenge of “smart rails”; and (iv) life cycle assessment (LCA) and circularity metrics are effective and indispensable tools in the decision-making process, since they help to quantify the potential environmental enhancement of different materials and solutions.

Infographic: The Backbone of Mobility: Interconnected Musculoskeletal Health

Infographic: The Backbone of Mobility: Interconnected Musculoskeletal Health

The Backbone of Mobility: Interconnected Musculoskeletal Health

The Backbone of Mobility: Interconnected Musculoskeletal Health

HGKM: An Efficient Hybrid Group Key Management for Unmanned Autonomous Vehicles MBN in Wireless Network Environment

Mobile ad hoc networks (MANET) have been seen as a related advancement to Group Key Management (GKM) applications. Remembering the true objective to guarantee amass applications and disallow uncertified clients from getting to the correspondence data that cannot be anchored by a remote MANET, including IP multicast, the singular gathered data content must remain encoded by a typical shared gathering key. Key administration is required to anchor the assurance of gathering the key and to safeguard those gathering data. GKM framework is associated with the remote system condition partners with three issues: execution, security, and system versatility. This article focuses on the Unmanned Aerial Vehicle (UAV)-mobile backbone node (MBN) remote system performance. The UAV-MBN Network condition is a military system that includes a proposal to group an important administrative structure. A half-and-half gathering key administration technique, which works on each target of UAV-MBN, is included in an arrangement to start two basic remote gathering key administration difficulties: (1) operational performance and (2) multiple-enrollment development. By working with minimal small-scale key administration, this strategy can diminish the execution cost associated with the key administration along with the increment operational execution of remote GKM. Scaled-down key organization is carried out in the context of these movement units. The key administration approach also restricted the operational procedure and decreased the operation’s cost in terms of key generation, figuring, and associated correspondence. Overall, the HGKM strategy that has been introduced enhances the operational process and functions effectively in reasonable remote areas.

Multimodal urban mobility and multilayer transport networks

Transportation networks, from bicycle paths to buses and railways, are the backbone of urban mobility. In large metropolitan areas, the integration of different transport modes has become crucial to guarantee the fast and sustainable flow of people. Using a network science approach, multimodal transport systems can be described as multilayer networks, where the networks associated to different transport modes are not considered in isolation, but as a set of interconnected layers. Despite the importance of multimodality in modern cities, a unified view of the topic is currently missing. Here, we provide a comprehensive overview of the emerging research areas of multilayer transport networks and multimodal urban mobility, focusing on contributions from the interdisciplinary fields of complex systems, urban data science, and science of cities. First, we present an introduction to the mathematical framework of multilayer networks. We apply it to survey models of multimodal infrastructures, as well as measures used for quantifying multimodality, and related empirical findings. We review modeling approaches and observational evidence in multimodal mobility and public transport system dynamics, focusing on integrated real-world mobility patterns, where individuals navigate urban systems using different transport modes. We then provide a survey of freely available datasets on multimodal infrastructure and mobility, and a list of open-source tools for their analyses. Finally, we conclude with an outlook on open research questions and promising directions for future research.

Can rail infrastructure determine perceived quality of service of suburban trains? Insights from Cercanias Madrid

Public transport modes in urban peripheries have a twofold function: buses provide the territorial capillarity, while the suburban rail acts as the backbone of mobility. Despite its relevance there, suburban rail usually runs on pre-existing tracks for heavy rail services. Moreover, in the current context of rail liberalization in Europe, the infrastructure manager and the rail operator are separate organizations with impacts on suburban rail. Therefore, it is important to discern the responsibilities of both agents in providing a better service, to promote a more sustainable mobility. This work aims to explore how the perceived quality of service (QoS) of suburban rail services can be influenced by the rail network infrastructure. The suburban rail network of Madrid (Cercanías) has been selected as case study because of the combination of pre-existing and new tracks as well as having a total of 9 regular lines, enough to perform this analysis. Data is gathered from the 2019 annual Cercanías traveler satisfaction survey. First, different aspects of the lines are thoroughly examined, such as the travel time between stops, shared sections or the location of the different sections within the metropolitan area. These factors are transformed into indicators to ease comparison. Based on the main indicators and the average QoS, lines are classified into 4 groups. The joint analysis of the infrastructure indicators and the attributes from the traveler satisfaction survey suggests that lines with similar QoS also have features common regarding to infrastructure and operation such as line length or travel time between stations.

Big data analytics for large‐scale UAV‐MBN in quantum networks using efficient hybrid GKM

SummaryA primary important aspect of wireless network domain is known to be secured communication as the signals are emphatically available and broadcasted through the air. Quantum wireless networks are a hot topic of research in recent years that made researchers to avail new techniques in this field. Big data is one of the major aspects that support large‐scale quantum network applications. As sensor nodes have resource constraints, it is more complex when using the traditional techniques of key establishment that only used for stable communication networks. Group‐related applications are also one of the important aspects in wireless network for sending and receiving messages from multiple users. Unfortunately, maintenance of security for the group‐oriented protocols is major issue due to the frequent changes in membership. In this paper, a hybrid GKM with re‐keying procedure is proposed to obtain a secure communication for the remote system of unmanned autonomous vehicle (UAV) with mobile backbone network (MBN). Here, the group controller is selected based on the simplified hybrid energy efficient distributed (HEED) protocol and honey key encryption algorithm is used by the key management center (KMC) for generating and distribution of key for the group's controller. The secure communication is explored using the key exchange mechanism between the nodes. The joining and leaving of a node from the group are initiated by the re‐keying process. The simulation results explain the improved performance of the proposed hybrid method when compared with other existing techniques in terms of privacy level, energy, memory, and time consumption.

BRT in the Philippines: A Solution to Manila and Cebu Traffic Problems?

Bus Rapid Transit (BRT), where buses run on dedicated roads at high frequency, almost in a metrorail manner, has been adopted as a backbone of urban mobility in the cities of many developing countries. Originally developed in South America (Curitiba, Brazil and Bogotá, Colombia), it has entered Asia with force, from Indonesia (Jakarta’s Transjakarta) to India and China. In the case of the Philippines, where intercity bus transportation is widely used due to the current lack of a railway network, city traffic, especially in Manila, is heavily congested, partly due to a high number of city buses running half-empty, the small proportion of road space relative to the vehicle population, and the insufficient provision of urban rail transportation. This paper examines the current situation of congestion, and its adverse effects, in the two main urban areas of the Philippines, Manila and Cebu, and the plans to implement BRT, looking at the routes chosen, the financing, the schedule of development and the expected outcomes. A major impediment to improvement in traffic conditions in the Philippines is the current boundary system, which coupled with the high number of bus operating companies leads to wild competition on the road, with the strong potential for multiple traffic jams and traffic accidents. Implementing a BRT system to make traffic smooth and fluid will require not only some road work and financing, but also a profound change in the way the bus system operates. It will also require a profound re-evaluation of intermodality between the renovated bus system, the rail system and two iconic Filipino transport modes, the aging jeepney and the lowly trisikel.

RANKING NODES IN COMPLEX NETWORKS: A CASE STUDY OF THE GAUBUS

Abstract. Connecting points of interest through a well-planned, inter-connected network provides manifold benefits to commuters and service providers. In the South African context, traffic congestion has become of great concern. Given how the South Africa community is slowly developing towards the use of multi-modes of mobility, the Gautrain network can be used to promote the use of multi-modes of mobility, as the Gautrain has been identified as the backbone of mobility within the Gauteng province. Currently commuters have the option to board the Gaubus (a form of Bus Rapid Transit) at their origin points which will take them to the Gautrain station to board the Gautrain. The problem to be solved arises when a commuter wishes to traverse from any bus stop to the Gautrain station, currently he/she only has one option and if the bus network has a shutdown at any point in the network the commuter’s journey will not be possible. In solving this problem, we consider the problem of graph robustness (that is creating new alternative routes to increase node/bus stop connectivity). We initial use Strava data, to identify locations were cyclist prefer to cycle and at what time of day. In graph theory, the nodes with most spreading ability are called influential nodes. Identification of most influential nodes and ranking them based on their spreading ability is of vital importance. Closeness centrality and betweenness are one of the most commonly used methods to identify influential nodes in complex networks. Using the Gaubus network we identify the influential nodes/ bus stops, using the betweenness centrality measure. The results reveal the influential nodes with the highest connectivity as these have cross-connections in the network. Identification of the influential nodes presents an important implication for future planning, accessibility, and, more generally, quality of life.

A Methodology to Evaluate Accessibility to Bus Stops as a Contribution to Improve Sustainability in Urban Mobility

Walking and transit are the backbone of sustainable mobility. Bus stops not only represent the connection between the two, but are also central in dictating the attractiveness of the latter. Accessibility of bus stops becomes, then, pivotal in increasing both attractiveness and sustainability of public transport. The paper describes a multi-step methodology to evaluate bus stops’ accessibility starting from a cluster of seven indicators describing objective and subjective features influencing passengers’ choice toward a given bus stop. The indicators are weighed by a questionnaire submitted to experts. Finally, a multicriteria analysis is developed to obtain a final score describing univocally the accessibility of each stop. Outcomes are mapped and a case study in Rome is reported as an example, with 231 bus and tram stops assessed accordingly. Results shows the relevance of the urban network and environment in evaluating the accessibility and in promoting more sustainable mobility patterns. Research innovation relies on the possibility to merge data from different fields into a specific GIS map and easily highlight for each bus stop the relationships between built environment, passengers’ comfort, and accessibility, with the concluding goal to provide advanced knowledge for further applications.

Design and Simulation of 1.28 Tbps Dense Wavelength Division Multiplex System Suitable for Long Haul Backbone

Abstract Wavelength division multiplex (WDM) system with on/off keying (OOK) modulation and direct detection (DD) is generally simple to implement, less expensive and energy efficient. The determination of the possible design capacity limit, in terms of the bit rate – distance product in WDM – OOK –DD systems is therefore crucial, considering transmitter/receiver simplicity, as well as energy and cost efficiency. A 32-channel WDM system is designed and simulated over 1000 km fiber length using Optsim commercial simulation software. The standard channel spacing of 0.4 nm was used in the C–band range from 1.5436 to 1.556 nm. Each channel used the simple non return to zero – on/off keying (NRZ – OOK) modulation format to modulate a continuous wave (CW) laser source at 40 Gbps using an external modulator, while the receiver uses a DD scheme. It is proposed that the design will be suitable for long haul mobile backbone in a national network, since up to 1.28 Tbps data rates can be transmitted over 1000 km. A bit rate length product of 1.28 Pbps.km was obtained as the optimum capacity limit in 32 channel dispersion managed WDM – OOK – DD system.

Topology control based on the group mobility model for mobile wireless mesh backbone networks

In this paper, we study the characteristics and components of mobile wireless mesh backbone networks (MWMBNs). How to maintain the heterogeneous network connectivity in mobile scenarios is important. We propose a topology control algorithm based on the group mobility model for MWMBN to maintain network connectivity in mobile scenarios. It includes the following work: MWMBNs is classified into the mobile wireless backbone node group (MWBNG) and unit groups (UGs). the MWBNG is composed of all the MWBNs while the UG is composed of a MWBN and several TNs connect it. In the MWBNG, we propose the reference points assignment algorithm (RPAA) based on the RPGM model. In the UG, the TNs has different communication radius with the MWBNs', we propose the topology control algorithm based on tolerate zone using nomadic community mobility, the control algorithm does not need to use any control information to maintain topology control or to change the routing table. The TNs change the self-position to maintain the connectivity with the MWBN. The simulation results show the topology control algorithm based on the group mobility model for MWMBN to maintain the heterogeneous network connectivity when they move together.

Topology control based on the group mobility model for mobile wireless mesh backbone networks

Topology control based on the group mobility model for mobile wireless mesh backbone networks

P‐AOMDV: An improved routing protocol for V2V communication based on public transport backbones

ABSTRACTThe Vehicular Ad Hoc Networks consider the vehicle‐to‐vehicle communication to provide safety and entertainment to their users. Vehicle‐to‐vehicle networks are self‐organized and self‐managed mobile networks with decentralized control, being independent of fixed infrastructures. These networks are also characterized by the high mobility of nodes (vehicles), the scarce or unbalanced traffic, and the restrictions imposed by the roads. Such characteristics imply lack of connectivity and low performance of the protocols. Many studies claim that the use of fixed infrastructure with classic routing protocols may provide connectivity and allow the use of Vehicular Ad Hoc Networks. Meanwhile, the associated costs are too high, which make them unable most of the times. A way to overcome these problems is to deploy a reliable infrastructure that will bear the routing protocol out. This paper proposes the construction of a new routing protocol, named Priority Ad Hoc On‐demand Multipath Distance Vector (P‐AOMDV), which has the capability of acting together with a mobile backbone formed by public transport buses (MOB‐NET) and, consequently, to minimize the effects of the lack of connectivity and to improve network performance. The P‐AOMDV can discover many routes between source and destination, allowing the nodes to have a broad vision of the network, being able to take routing decisions considering metrics that are not limited to the number of hops. Simulation experiments have shown that the pair P‐AOMDV/MOB‐NET can improve metrics like packet delivery ratio (PDR) and active route ratio (ARR) and, at the same time, minimize problems due to route breakage and route unavailability.

Current and Future Trends of the Automotive Industry

Mobility, and especially individual physical mobility, is still an essential component of nearly all societies.The combustion engine was for more than a hundred years, and is still today, the backbone of road-based mobility. However, the guarantor for the triumphant advance of the combustion engine was by far not its technical superiority over its electrical rival at the beginning of the automobile era, but the energy density and the easy worldwide availability of fossil fuels as a means of energy storage. So, e.g. to store the energy equivalent of one kg Gasoline, a lithium ion battery with a mass of about 180 kg would be required (Schramm, 2012), even if the higher efficiency of the electric motor vs. the combustion engine is taken into account. Actually an electric motor is much better suited as a drive source for a motor vehicle as an internal combustion engine. Only the achievable energy density along with the cost of its chemical-process based storage, the battery, still prevent its immediate breakthrough in the automotive drive technology. Nevertheless, the German Government has set the target to bring at least a million electrified motor vehicles on Germany's roads by 2020, which is already impossible to reach from today’s perspective. However, strategies are needed to achieve a sustainable transition to electric mobility. This, in addition to continued research on high-efficiency batteries which also includes the development of vehicles that offer a good compromise between coverage, costs and consumption while satisfying the mobility needs of their users. Another trend that will lead to a paradigm shift in the use of individually-powered vehicles is the automation of the task of driving up to the highly automated or even autonomous vehicle. The technical prerequisites like sensors and actuators for these new systems are already available at least for application on motorways and rural regions, e.g. in Germany. More activities are required for robust algorithms and strategies to hand over control back to the driver in complex situations and even vice versa from the driver to the car in cases where the driver is unable to further control his car, e.g. in case of a heart attack. Another open field is the question of the responsibility in case of an accident along with even ethic problems. A widely uncharted aspect is the individual customer who is expected and needed to buy the vehicle and his/her behaviour of vehicle use. For this reason currently a variety of activities is underway to find out how cars are actually being used in different countries. Those different usage scenarios would have a significant effect on the availability, environmental impact and economics notably of electrified vehicles. So a project funded by the German government is the Ruhr Car Sharing Project operated by the University of Duisburg-Essen and their partners for several years especially for electric and hybrid vehicles (Tewiele et al., 2015). Still unidentified, however, is the influence of a large proportion of electrified and highly automated vehicles on consumption, the total CO2 emissions and traffic jams (Jeschke et al., 2014). For this purpose extensive field experiments are conducted along with activities using simulation models to predict these impacts reliably for the future. It has to be made possible to successfully derive development strategies for Europe and other regions as well (Schuller et al., 2015). Despite all difficulties, we are confident that there will be solutions for robust environment friendly technical solutions, acceptance by humans and even legal obstacles. As Albert Einstein once said, “Amid the difficulty lies opportunity.”

Increasing Connectivity in VANETs Using Public Transport Backbones

The Vehicular Ad Hoc Networks (VANETs) can be deployed in several regions of urban environments in different days and times, depending on the flow of vehicles. Because of that, the network behavior concerning topological aspects may vary considerably and the guarantee of connectivity between vehicles is a great challenge. The utilization of a fixed infrastructure can enable the use of VANETs, however, this kind of architecture presents prohibitive costs. In big cities, the metropolitan buses that travel on exclusive lanes may be used to set up a metropolitan vehicular data network (backbone). Therefore, this paper considers the implementation of a live mobile backbone, totally ad hoc (BMVA), which provide infrastructure and increase the network connectivity. In order to demonstrate the viability of the BMVA, statistical analysis were performed based on real data from express buses, which travel on exclusive lanes in the city of Curitiba (PR). Statistical, analytical and simulation results confirm that the buses that travel on exclusive lanes could be used to build a totally ad hoc data network and to provide very good network connectivity. In order to exploit the intrinsic connectivity provided by BMVA a new routing protocol, called P-AODV, is also proposed. The P-AODV aims to give priority to the nodes belonging to BMVA during the route discovery process, thereby improving the network performance.

Detection and Removal of Gray, Black and Cooperative Black Hole Attacks in AODV Technique

Mobile ad hoc network (MANET) is an autonomous self-configuring infrastructure-less wireless network. MANET is vulnerable to a lot of routing security threats due to unreliability of its nodes that are highly involved in the routing process. In this paper, a new technique is proposed to enhance the security of one of the most popular MANET routing protocols that is called Ad hoc on Demand Distance Vector (AODV) with minimum routing overhead and high packet delivery ratio. The proposed technique intends to detect and remove black, gray, and cooperative black hole AODV attacks depending on a mobile backbone network constructed from randomly moving regular MANET nodes based on their trust value, location, and power. The backbone network monitors regular nodes as well as each other to periodically estimate monitoring trust values which represent the reliability of each node in the network. The drop in the monitoring trust value of any node is used as a clue to its malicious behavior. The backbone network also tries to bait the malicious nodes to reply to a request for a route to fake destination address. The proposed technique uses the control packets of the AODV to exchange its control information which highly reduces the overhead. The simulation results show that the performance of the proposed technique is more secure than AODV and the other recently introduced techniques.

Improving VANETs Connectivity with a Totally Ad Hoc Living Mobile Backbone

The vehicular ad hoc network (VANET) for intelligent transportation systems is an emerging concept to improve transportation security, reliability, and management. The network behavior can be totally different in topological aspects because of the mobility of vehicular nodes. The topology can be fully connected when the flow of vehicles is high and may have low connectivity or be invalid when the flow of vehicles is low or unbalanced. In big cities, the metropolitan buses that travel on exclusive lanes may be used to set up a metropolitan vehicular data network (backbone), raising the connectivity among the vehicles. Therefore, this paper proposes the implementation of a living mobile backbone, totally ad hoc (MOB-NET), which will provide infrastructure and raise the network connectivity. In order to show the viability of MOB-NET, statistical analyses were made with real data of express buses that travel through exclusive lanes, besides evaluations through simulations and analytic models. The statistic, analytic, and simulation results prove that the buses that travel through exclusive lanes can be used to build a communication network totally ad hoc and provide connectivity in more than 99% of the time, besides raising the delivery rate up to 95%.

A sociality-aware approach to computing backbone in mobile opportunistic networks

There are increasing interests on mobile opportunistic networks which have promising applications. Constructing a mobile backbone can effectively improve the packet delivery performance of a mobile opportunistic network by excluding poor relay nodes and reducing packet collisions. However, it is highly challenging to construct an effective mobile backbone because of the absence of the quantitative relationship between the network performance and the selection of backbone nodes, and expositive search space. We theoretically prove that the backbone construction problem is NP-Complete (NPC). By analyzing the real traces collected from around 100 users, we reveal that the nodes exhibit clear sociality. Motivated by this observation, we explicitly take such node sociality into account when computing the backbone for mobile opportunistic networks and we incrementally propose three algorithms for computing the mobile backbone. One of the algorithms is proved to achieve near-optimal solution under a specific model. Trace-driven simulations have been conducted and simulation results demonstrate that the sociality-aware algorithms can achieve low delivery delay and high delivery ratio.

Minimization of Backbone Nodes in Wireless Mobile Backbone Networks using Approximation Algorithms

Minimization of Backbone Nodes in Wireless Mobile Backbone Networks using Approximation Algorithms