Advanced Fade Countermeasures for DVB-S2 Systems in Railway Scenarios

This paper deals with the analysis of advanced fade countermeasures for supporting DVB-S2 reception by mobile terminals mounted on high-speed trains. Recent market studies indicate this as a potential profitable market for satellite communications, provided that integration with wireless terrestrial networks can be implemented to bridge the satellite connectivity inside railway tunnels and large train stations. In turn, the satellite can typically offer the coverage of around 80% of the railway path with existing space infrastructure. This piece of work, representing the first step of a wider study, is focusing on the modifications which may be required in the DVB-S2 standard (to be employed in the forward link) in order to achieve reliable reception in a challenging environment such as the railway one. Modifications have been devised trying to minimize the impact on the existing air interface, standardized for fixed terminals

Insights in the cost of continuous broadband Internet on trains for multi-service deployments by multiple actors with resource sharing

The economic viability of broadband Internet services on trains has always been proved difficult, mainly due to a high investment cost and low willingness to pay by train passengers, but also due to unused opportunities such as non-passenger services (e.g. train performance monitoring, crew services) and optimization of the resources consumed to offer Internet services. Evaluating opportunities to improve the return on investment is therefore essential towards profitability of the business case. By efficiently sharing resources amongst services, costs can be pooled over several services in order to reduce the investment cost per service. Current techno-economic evaluation models are hard to apply to cost allocation in a multi-service deployment with multiple actors and resource sharing. We therefore propose a new evaluation model and apply it to a deployment of Internet services on trains. We start with a detailed analysis of the technical architecture required to provide Internet access on trains. For each component, we investigate the impact by the different services on resource consumption. The proposed techno-economic evaluation model is then applied in order to calculate the total cost and allocate the used and unused resources to the appropriate services. In a final step, we calculate the business case for each stakeholder involved in the offering of these services. This paper details the proposed model and reports on our findings for a multi-service deployment by multiple actors. Results show important benefits for the case that considers the application of resource sharing in a multi-service, multi-actor scenario and the proposed model produces insights in the contributors to the cost per service and the unused amount of a resource. In addition, ex-ante insights in the cost flows per involved actor are obtained and the model can easily be extended to include revenue flows to evaluate the profitability per actor. As a consequence, the proposed model should be considered to support and stimulate upcoming multi-actor investment decisions for Internet-based multi-service offerings on-board trains with resource sharing

Wireless communication, identification and sensing technologies enabling integrated logistics: a study in the harbor environment

In the last decade, integrated logistics has become an important challenge in the development of wireless communication, identification and sensing technology, due to the growing complexity of logistics processes and the increasing demand for adapting systems to new requirements. The advancement of wireless technology provides a wide range of options for the maritime container terminals. Electronic devices employed in container terminals reduce the manual effort, facilitating timely information flow and enhancing control and quality of service and decision made. In this paper, we examine the technology that can be used to support integration in harbor's logistics. In the literature, most systems have been developed to address specific needs of particular harbors, but a systematic study is missing. The purpose is to provide an overview to the reader about which technology of integrated logistics can be implemented and what remains to be addressed in the future

Satellite-3G Hybrid Networks: Impact of ACM and ARQ on TCP Performance

The adoption of satellite systems in providing broadband transmissions to mobile users such as trains, buses and vans is expected to be an interesting solution. The scenario we considered refers to a hybrid network architecture, where a geostationary satellite forward link and a terrestrial 3G return link are used in order to exploit both the high bandwidth of a satellite channel and the lower propagation delay of a terrestrial path. The resulting round-trip delay is much shorter than that one experienced by using both the forward and return link via satellite. This is particularly appealing for overcoming the TCP efficiency degradation in high delay-bandwidth product and error prone channels. In this hybrid scenario, we used simulation results to compare the goodput of four of the most popular TCP variants, in the presence of a GOOD-BAD satellite channel, as the one experienced by mobile users. We applied an Adaptive Coding and Modulation (ACM) technique as well, and studied its impact on TCP efficiency, when used both alone and in cooperation with an Automatic Repeat reQuest (ARQ) scheme of the Selective Repeat (SR) type with low persistency. Results obtained indicate that this hybrid architecture is advantageous for TCP transmissions in terms of average goodput, and that ACM is effective only if it is jointly used with ARQ schemes

A novel network architecture for train-to-wayside communication with quality of service over heterogeneous wireless networks

In the railway industry, there are nowadays different actors who would like to send or receive data from the wayside to an onboard device or vice versa. These actors are e.g., the Train Operation Company, the Train Constructing Company, a Content Provider, etc. This requires a communication module on each train and at the wayside. These modules interact with each other over heterogeneous wireless links. This system is referred to as the Train-to-Wayside Communication System (TWCS). While there are already a lot of deployments using a TWCS, the implementation of quality of service, performance enhancing proxies (PEP) and the network mobility functions have not yet been fully integrated in TWCS systems. Therefore, we propose a novel and modular IPv6-enabled TWCS architecture in this article. It jointly tackles these functions and considers their mutual dependencies and relationships. DiffServ is used to differentiate between service classes and priorities. Virtual local area networks are used to differentiate between different service level agreements. In the PEP, we propose to use a distributed TCP accelerator to optimize bandwidth usage. Concerning network mobility, we propose to use the SCTP protocol (with Dynamic Address Reconfiguration and PR-SCTP extensions) to create a tunnel per wireless link, in order to support the reliable transmission of data between the accelerators. We have analyzed different design choices, pinpointed the main implementation challenges and identified candidate solutions for the different modules in the TWCS system. As such, we present an elaborated framework that can be used for prototyping a fully featured TWCS