Enabling Multi-Mission Interoperable UAS Using Data-Centric Communications

We claim the strong potential of data-centric communications in Unmanned Aircraft Systems (UAS), as a suitable paradigm to enhance collaborative operations via efficient information sharing, as well as to build systems supporting flexible mission objectives. In particular, this paper analyzes the primary contributions to data dissemination in UAS that can be given by the Data Distribution Service (DDS) open standard, as a solid and industry-mature data-centric technology. Our study is not restricted to traditional UAS where a set of Unmanned Aerial Vehicles (UAVs) transmit data to the ground station that controls them. Instead, we contemplate flexible UAS deployments with multiple UAV units of different sizes and capacities, which are interconnected to form an aerial communication network, enabling the provision of value-added services over a delimited geographical area. In addition, the paper outlines an approach to address the issues inherent to the utilization of network-level multicast, a baseline technology in DDS, in the considered UAS deployments. We complete our analysis with a practical experience aiming at validating the feasibility and the advantages of using DDS in a multi-UAV deployment scenario. For this purpose, we use a UAS testbed built up by heterogeneous hardware equipment, including a number of interconnected micro aerial vehicles, carrying single board computers as payload, as well as real equipment from a tactical UAS from the Spanish Ministry of Defense.This article was partially supported by the European H2020 5GRANGE project (grant agreement 777137), and by the 5GCity project (TEC2016-76795-C6-3-R) funded by the SpanishMinistry of Economy and Competitiveness

Epidemic broadcast trees

There is an inherent trade-off between epidemic and deterministic tree-based broadcast primitives. Tree-based approaches have a small message complexity in steady-state but are very fragile in the presence of faults. Gossip, or epidemic, protocols have a higher message complexity but also offer much higher resilience. This paper proposes an integrated broadcast scheme that combines both approaches. We use a low cost scheme to build and maintain broadcast trees embedded on a gossip-based overlay. The protocol sends the message payload preferably via tree branches but uses the remaining links of the gossip overlay for fast recovery and expedite tree healing. Experimental evaluation presented in the paper shows that our new strategy has a low overhead and that is able to support large number of faults while maintaining a high reliability.This work was partially supported by project P-SON: Probabilistically Structured Overlay Networks (POSC/EIA/60941/2004)

Experimentation with MANETs of Smartphones

Mobile AdHoc NETworks (MANETs) have been identified as a key emerging technology for scenarios in which IEEE 802.11 or cellular communications are either infeasible, inefficient, or cost-ineffective. Smartphones are the most adequate network nodes in many of these scenarios, but it is not straightforward to build a network with them. We extensively survey existing possibilities to build applications on top of ad-hoc smartphone networks for experimentation purposes, and introduce a taxonomy to classify them. We present AdHocDroid, an Android package that creates an IP-level MANET of (rooted) Android smartphones, and make it publicly available to the community. AdHocDroid supports standard TCP/IP applications, providing real smartphone IEEE 802.11 MANET and the capability to easily change the routing protocol. We tested our framework on several smartphones and a laptop. We validate the MANET running off-the-shelf applications, and reporting on experimental performance evaluation, including network metrics and battery discharge rate.Comment: 6 pages, 7 figures, 1 tabl

Improving the Multi-Channel Hybrid Data Dissemination System

A major problem with the Internet and web-based applications is the scalable delivery of data. Lack of scalability can hinder performance and decrease the ability of a system to perform as originally designed. One of the most promising solutions to this scalability problem is to use a multiple channel hybrid data dissemination server to deliver requested information to users. This solution provides the high scalability found in multicast, with the low latency found in unicast. A multiple channel hybrid server works by using a push-based multicast channel to deliver the most popular data to users, and reserves the pull-based unicast channel for user requests and delivery of less popular data.The adoption of a multiple channel hybrid data dissemination server, however, introduces a variety of data management problems. In this dissertation, we propose an improved multiple channel hybrid data dissemination model, and propose solutions to three fundamental data management problems that arise in any multiple channel hybrid scheme. In particular, we address the push popularity problem, the document classification problem, and the bandwidth division problem. We also propose a multicast pull channel to the common two-channel hybrid scheme. Our hypothesis that this new channel both improves scalability, and decreases variances in response times, is confirmed by our extensive experimental results. We develop a fully functioning architecture for our three-channel hybrid scheme. In a real world environment, our middleware is shown to provide high scalability for overloaded web servers, while keeping the response times experienced by clients at a minimum. Further, we demonstrate that the practical impact of this work extends to other broadcast-based environments, such as a wireless network

Elaborating a decentralized market information system

A Decentralized Market Information System (DMIS) that aggregates and provides information about markets is an important component for achieving markets in Grid and Peer-to-Peer systems. The proposed work is the development of a framework for the DMIS, which fulfils the economic provision within the main technical requirements like scalability towards nodes and data attributes and robustness against failures. The proposed work also allows obtaining results concerning the trade-off between economic benefits and technical costs. Introducing dynamic adaptive processes promises improvements in efficiency with regards to distributed queries and routing structures. This research proposal presents and discusses the research questions and challenges, the current knowledge and the research methodology proposed for the development of the DMIS framework.Peer Reviewe

Towards a generic group communication service

View synchronous group communication is a mature technology that greatly eases the development of reliable distributed applications by enforcing precise message delivery semantics, especially in face of faults. It is therefore found at the core of multiple widely deployed and used middleware products. Although the implementation of a group communication system is a complex task, application developers may benefit from the fact that multiple group communication toolkits are currently available and supported. Unfortunately, each communication toolkit has a different interface, that differs from every other interface in subtile syntactic and semantic aspects. This hinders the design, implementation and maintenance of applications using group communication and forces developers to commit beforehand to a single toolkit, thus imposing a significant hurdle to portability. In this paper we propose jGCS, a generic group communication service for Java, that specifies an interface as well as minimum semantics that allow application portability. This interface accommodates existing group communication services, enabling implementation independence. Furthermore, it provides support for the latest state-of-art mechanisms that have been proposed to improve the performance of group-based applications. To support our claims, we present and experimentally evaluate implementations of jGCS for several major group communication systems, namely, Appia, Spread/FlushSpread and JGroups, and describe the port of a large middleware product to jGCS.This work was partially supported by the IST project GORDA (FP6-IST2-004758

The SATIN component system - a metamodel for engineering adaptable mobile systems

Mobile computing devices, such as personal digital assistants and mobile phones, are becoming increasingly popular, smaller, and more capable. We argue that mobile systems should be able to adapt to changing requirements and execution environments. Adaptation requires the ability-to reconfigure the deployed code base on a mobile device. Such reconfiguration is considerably simplified if mobile applications are component-oriented rather than monolithic blocks of code. We present the SATIN (system adaptation targeting integrated networks) component metamodel, a lightweight local component metamodel that offers the flexible use of logical mobility primitives to reconfigure the software system by dynamically transferring code. The metamodel is implemented in the SATIN middleware system, a component-based mobile computing middleware that uses the mobility primitives defined in the metamodel to reconfigure both itself and applications that it hosts. We demonstrate the suitability of SATIN in terms of lightweightedness, flexibility, and reusability for the creation of adaptable mobile systems by using it to implement, port, and evaluate a number of existing and new applications, including an active network platform developed for satellite communication at the European space agency. These applications exhibit different aspects of adaptation and demonstrate the flexibility of the approach and the advantages gaine

Service-oriented middleware for wireless sensor networks

There is a wide range of applications for wireless sensor networks (WSNs) with different needs. The network infrastructure and data dissemination protocol change according to each specific application requirement. To achieve the best network performance, it is important to adapt the network operation to the application needs. We propose a middleware system for WSNs, which provides a layer between user applications and the network. Such middleware offers an automatic choice of the network configuration and data dissemination strategy