Abstract

The call for papers resulted in a high number of submis- sions, from which we have been able to select 12 excellent papers dealing with the different aspects of satellite commu- nications and navigation. Multiple-input multiple-output (MIMO) techniques are attracting a considerable amount of attention from within the terrestrial wireless community. The first paper of this spe- cial issue, “Multisatellite MIMO communications at Ku band and above: investigations on spatial multiplexing for capac- ity improvement and selection diversity for interference mit- igation,” considers the application of such technology over a satellite platform operating in the Ku band and above. The paper considers how MIMO can be used to increase capac- ity by using a satellite spatial multiplexing system and how antenna selection can be used to mitigate interference. The next paper “Investigations in satellite MIMO channel model- ing: accent on polarization” looks at MIMO systems from the polarization diversity point of view and dwells on the satellite cooperative communication concepts. Switch and stay combining (SSC) is a form of diversity technique used in digital receivers to compensate for fade events introduced by the mobile channel. The third paper “Performance analysis of SSC diversity receivers over corre- lated Ricean fading satellite channels” investigates the per- formance of dual-branch SSC receivers for different fading channel characteristics. The next four papers deal with the emerging scenario of mobile digital video broadcasting (DVB-S2 and RCS mo- bile). Alternative approaches to counteracting fading chan- nels introduced when operating in a train environment re- ceiving satellite DVB-S2 are presented in the paper “Ad- vanced fade countermeasures for DVB-S2 systems in railway scenarios.” Here, as a result of simulation analysis, antenna diversity and packet-level forward error correction mecha- nisms are proposed and their impact is evaluated with respect to the receiver design and system complexity. The theme of DVB-S2 is continued with the paper “Capacity versus bit er- ror rate trade-off in the DVB-S2 forward link,” which inves- tigates how satellite capacity can be optimised for DVB-S2 transmissions. The DVB return channel via satellite (DVB- RCS) is then addressed in “Frequency estimation in iterative interference cancellation applied to multibeam satellite sys- tems,” which considers the application of interference cancel- lation on the reverse link of a multibeam satellite system, us- ing DVB-RCS with convolutional coding as an example. The paper “A QoS architecture for DVB-RCS next-generation satellite networks” proceeds to design and emulate a quality- of-service (QoS) architecture that demonstrates using real multimedia applications how QoS can be supported over a DVB-RCS network. 2 EURASIP Journal on Wireless Communications and Networking Synchronization aspects are dealt with in “Maximum likelihood timing and carrier synchronization in burst-mode satellite transmissions.” The paper addresses the problem of achieving synchronisation for a burst-mode satellite trans- mission over an AWGN channel. The subject of burst trans- mission continues with the paper “Burst format design for optimum joint estimation of Doppler-shift and Doppler- rate in packet satellite communications,” which considers optimising the burst-format of packet-oriented transmis- sions by proposing very-low-complexity algorithms for car- rier Doppler-shift and Doppler-rate estimation. A network comprising satellite and high-altitude plat- forms is considered in the paper “TCP-call admission con- trol interaction in multiplatform space architectures.” Cross- layer techniques are implemented by means of TCP feeding back into call admission control (CAC) procedures for the purpose of prevention of congestion and improvement in QoS. Finally, since navigation is an extremely important part of the satellite system family, we have included two papers. The first paper “Efficient delay tracking methods with side- lobes cancellation for BOC-modulated signals” deals with bi- nary offset carrier (BOC) modulation, which is adopted in typical navigation systems. The paper considers how to improve the tracking of the main lobe of the BOC-modulated signal by using sidelobe suppression techniques. An alternative approach based on filter bank processing is presented in “Analysis of filter-bank-based methods for fast serial acqui- sition of BOC-modulated signals” to conclude the special issue. Document type: Part of book or chapter of book

Abstract

Traffic engineering encompasses a set of techniques that can be used to control the flow of traffic in data networks. We discuss several of those techniques that have been developed during the last few years. Some techniques are focused on pure IP networks while others have been designed with emerging technologies for scalable Quality of Service (QoS) such as Differentiated Services and MPLS in mind. We first discuss traffic engineering techniques inside a single domain. We show that by using a non-linear programming formulation of the traffic engineering problem it is possible to meet the requirements of demanding customer traffic, while optimising the use of network resources, through the means of an automated provisioning system. We also extend the functionality of the traffic engineering system through policies. In the following, we discuss the techniques that can be used to control the flow of packets between domains. First, we briefly describe interdomain routing and the Border Gateway Protocol (BGP). Second, we summarise the characteristics of interdomain traffic based on measurements with two different Internet Service Providers. We show by simulations the limitations of several BGP-based traffic engineering techniques that are currently used on the Internet. Then, we discuss the utilisation of BGP to exchange QoS information between domains by using the QOS_NLRI attribute to allow BGP to select more optimum paths. Finally, we consider the multi-homing problem and analyse the current proposed IPv6 multi-homing solutions are analysed along with their impact on communication quality.

Abstract

The Maritime Spatial Planning (MSP) Challenge game: Short Sea Shipping (SSS) Edition is a table-top strategy board game, designed for policy-makers and stakeholders involved in MSP, short-sea shipping and the Blue Economy. It is a ‘serious game’, allowing the development of a better understanding of the issues involved in MSP through creative and imaginative role playing, taking into account the relevant professional and personal experience of the players. The authors present and discuss the use of the MSP Challenge board game to test how, and to what extent, the concept can help stakeholders understand Maritime Spatial Planning.

Abstract

Abstract A testing-based faster-than relation has previously been developed that compares the worst-case efficiency of asynchronous systems. This approach reveals that pipelining does not improve efficiency in general; that it does so in practice depends on assumptions about the user behaviour. Accordingly, the approach was adapted to a setting where user behaviour is known to belong to a specific, but often occurring class of request–response behaviours; some quantitative results on the efficiency of the respective so-called response processes were given. In particular, it was shown that in the adapted setting a very simple case of a pipelined process with two stages is faster than a comparable atomic processing of the two stages. In this paper, we determine the performance of general pipelines, which is not so easy in an asynchronous setting. Pipelines are built with a chaining operator; we also study whether the adapted faster-than relation is compatible with chaining and two other parallel composition operators, and give results on the performance of the respective compositions. These studies also demonstrate how rich the request–respond setting is.

Abstract

Assigning and scheduling vehicle routes in a stochastic time-dependent environment is a crucial management problem. The assumption that in a real-life environment everything goes according to an a priori determined static schedule is unrealistic. Our methodology builds on earlier work in which the traffic congestion is captured in an analytical way using queueing theory. The congestion is then applied to the VRP problem. In this paper, we introduce the variability in traffic flows into the model. This allows for an evaluation of the routes based on the uncertainty involved. Different experiments show that the risk taking behavior of the planner can be taken into account during optimization. As more weight is given to the variability component, the resulting optimal route will take a slightly longer travel time, but will be more reliable. We propose a powerful objective function that is easily implemented and that captures the trade-off between the average travel time and its variance. The evaluation of the solution is done in terms of the 95th-percentile of the travel time distribution (assumed to be lognormal), which reflects well the quality of the solution in this stochastic time-dependent environmen

Abstract

Due to the geographical distance between producers and consumers, the impact of our current transport system on the environment is considerable. In an ideal, more sustainable transport system, several complementary transport modes are available, so that the most suitable route can always be selected. Because multiple transport modes and operators are involved, decision processes become more complex. That is why this research focuses on the development of innovative transport systems with realistic characteristics and planning limitations, in order to stimulate intermodal transport. Two planning tools have been developed to support decisions made by intermodal transport planners. It concerns on the one hand the integration of intermodal short and long distance routing and on the other hand the loading planning of trains. Both tools consist of fast planning algorithms that can handle realistic problem properties and can be integrated into transport management systems. The objective is to minimize transport costs and to make maximum use of available transport capacity.

Abstract

In order to improve the efficiency of transportation networks, it is critical to forecast traffic congestion. Large-scale traffic congestion data have become available and accessible, yet they need to be properly represented in order to avoid overfitting, reduce the requirements of computational resources, and be utilized effectively by various methodologies and models. Inspired by pooling operations in deep learning, we propose a representation framework for traffic congestion data in urban road traffic networks. This framework consists of grid-based partition of urban road traffic networks and a pooling operation to reduce multiple values into an aggregated one. We also propose using a pooling operation to calculate the maximum value in each grid (MAV). Raw snapshots of traffic congestion maps are transformed and represented as a series of matrices which are used as inputs to a spatiotemporal congestion prediction network (STCN) to evaluate the effectiveness of representation when predicting traffic congestion. STCN combines convolutional neural networks (CNNs) and long short-term memory neural network (LSTMs) for their spatiotemporal capability. CNNs can extract spatial features and dependencies of traffic congestion between roads, and LSTMs can learn their temporal evolution patterns and correlations. An empirical experiment on an urban road traffic network shows that when incorporated into our proposed representation framework, MAV outperforms other pooling operations in the effectiveness of the representation of traffic congestion data for traffic congestion prediction, and that the framework is cost-efficient in terms of computational resources. Document type: Article

Abstract

This work proposes a numerical methodology for the calculation of currents and voltages induced on underground pipelines by nearby overhead power lines. A previously developed quasi-3D methodology is extended, allowing the investigation of nonparallel routings of the pipelines with respect to the power lines. The proposed technique is based on a discretization of the pipeline path into several segments parallel to the power line. The section of the corridor corresponding to each pipeline segment is regarded as an electrical multi-port component, whose electrical parameters are extracted via finite element 2D analysis. Then, the obtained components are integrated into a network embodying the physical characteristics of the whole corridor. In this way, the circuital analysis is used to extend the capabilities of a standard two-dimensional field analysis. The proposed methodology is employed to simulate a pipeline running parallel to a power line for a distance of 12km. Afterwards, several nonparallel configurations – consisting of crossings between a pipeline and a power line – are assessed. The physical consequences of the crossing are discussed and a convergence study is performed to investigate the optimal pipeline subdivision procedure to be adopted for a set of different crossing angles.