Carolina Fortuna

Trends in the development of communication networks: Cognitive networks

One of the main challenges already faced by communication networks is the efficient management of increasing complexity. The recently proposed concept of cognitive network appears as a candidate that can address this issue. In this paper, we survey the existing research work on cognitive networks, as well as related and enabling techniques and technologies. We start with identifying the most recent research trends in communication networks and classifying them according to the approach taken towards the traditional layered architecture. In the analysis we focus on two related trends: cross-layer design and cognitive networks. We classify the cognitive networks related work in that mainly concerned with knowledge representation and that predominantly dealing with the cognition loop. We discuss the existing definitions of cognitive networks and, with respect to those, position our understanding of the concept. Next, we provide a summary of artificial intelligence techniques that are potentially suitable for the development of cognitive networks, and map them to the corresponding states of the cognition loop. We summarize and compare seven architectural proposals that comply with the requirements for a cognitive network. We discuss their relative merits and identify some future research challenges before we conclude with an overview of standardization efforts.

Exposing real world information for the web of things

In this paper, we propose SemSense architecture for collecting real world data from a physical system of sensors and publishing it on the Web, thus contributing to the Web of Things. SemSense comprises of four components: (1) the data collection component, (2) the storage component (3) the semantic enrichment component and (4) the publishing component, which are described and implemented for an existing deployment of a sensor network. Through these components, the real world data is collected from the physical devices, processed, equipped with semantic information and published on the Web. The paper addresses challenges of efficiently collecting data and meta-data from sensors and publishing it following the linked data principles.

Evaluation of Wavelength Requirements for Stratospheric Optical Transport Networks

This paper addresses the concept of optical transport network based on high altitude platforms (HAPs) flying in lower stratosphere and equipped with optical communications payload. The stratospheric transport network is formed of optical links between HAPs and optical backhaul uplinks and downlinks between HAPs and ground stations (GSs) hosting gateways to the backbone network. In order to consider limitations of free space optics (FSO) for the dimensioning of stratospheric optical transport network (OTN), we investigate the physical layer aspects for a DWDM based optical interplatform link (IPL). Taking into account the physical constraints imposed by FSO, we estimate the number of wavelengths required for full interconnectivity without wavelength conversions. We are using an analytical approach for bus and full mesh regular topologies, and a numerical approach for circumcircled star, ring and star regular topologies. We also evaluate the performance of a representative network with irregular topology using different routing and wavelength assignment algorithms. We show that the number of wavelengths needed to achieve full interconnectivity strongly depends on the physical topology of the network, and that adaptive routing yields better overall performance of the network compared to fixed and fixed alternate routing. The analysis also shows that resources in realistic network topologies tend to be used very inefficiently, which could be improved by traffic engineering solutions or wavelength conversions.

A hybrid approach to QoS-aware Web Service classification and recommendation

The proliferation of Web Services (WSs) has given significant importance to the Quality of Service (QoS) in the discovery process. This paper introduces a hybrid system which combines semantic technology and logic based reasoning (i.e. OpenCyc) with numerical calculus to classify, evaluate and then recommend QoS aware WSs. The system is able to answer high level composed functional and/or nonfunctional queries related to a real-life dataset containing 2500 WS, therefore enabling classification and recommendation of WSs.

Dynamic composition of services for end-to-end information transport

An increasing number of communication technologies in access and core segments of the network belonging to different providers and subject to different network design criteria are making networks complex and difficult to manage. In such networks it is also more difficult to guarantee requested levels of quality of service. Service oriented design can be the answer to problems facing the providers of services for information transport. In this article we propose an end-to-end service composition for information transport based on principles from service oriented architecture (i.e., dynamically composing transport services with characteristics matching the requirements of a given application). SOA principles are similar to those behind the division of labor, and therefore should give providers incentive to adopt them to make better use of resources and increase revenue. As we show, some SOA concepts are similar to concepts in the open systems interconnection reference model, with the key advantages of dynamism and flexibility. We discuss service oriented networks based on transport service composition across access and core segments, and describe access network selection for online gaming. In particular, we show how semantic technologies can be used for layer 2 queries and discuss the advantages of using knowledge bases over traditional approaches.

GITAR: generic extension for internet-of-things architectures enabling dynamic updates of network and application modules

Abstract The Internet-of-Things (IoT) represents the third wave of computing innovation and relies on small, cheap and/or energy efficient devices, densely deployed in various spaces. Automatically managing, updating and upgrading the software on these devices, particularly the network stacks, with new, improved functionality is currently a major challenge. In this paper we propose GITAR, a generic extension for Internet-of-Things architectures, that enables dynamic application and network level upgrades in an efficient way. GITAR consists of four design concepts which can be applied to any operating system running on IoT/M2M devices. The proof of concept implementation in this paper uses the Contiki OS and the evaluation, based on analytical and experimental methods, shows that GITAR i) is up to 14% more efficient in terms of memory usage and ii) has less or similar run-time CPU overhead as state of the art solutions while offering upgrade functionality down to the network level and iii) can reuse existing Contiki network protocols for dynamic updates without requiring modifications to the code.

Low-Cost Testbed Development and Its Applications in Cognitive Radio Prototyping

Having a huge potential to improve the way radio spectrum is being used, the techniques that are used for the research in cognitive radio are maturing and therefore move from being evaluated in a simulation environment to more realistic environments such as dedicated testbeds. In this chapter we describe our experiences with the design, deployment and experimental use of the LOG-a-TEC embedded, outdoor cognitive radio testbed, based on the VESNA sensor node platform. We describe the choice of experimental low-cost reconfigurable radio frontends for LOG-a-TEC and discuss the potential capabilities of custom designs. The core part of this chapter gives practical experiences with designing the embedded testbed infrastructure, covering topology design and performance evaluation of the management network as well as our considerations in the choice of network protocols employed in the LOG-a-TEC testbed. Finally, we provide two use cases where the LOG-a-TEC testbed has been used for performing experiments with cognitive radio, one relevant to the investigation of coexistence of primary and secondary users in TV white spaces and the other addressing power allocation and interference control in the case of shared spectrum.

Mashups for the Web of Things

The Web of Things (WoT) together with mashup-like applications is gaining popularity with the development of the Internet towards a network of interconnected objects, ranging from cars and transportation cargos to electrical appliances. In this chapter we provide a brief architectural overview of technologies which can be used in WoT mashups with emphasis on artificial intelligence technologies such as conceptualization and stream processing. We also look at data sources and existing WoT mashups. In the last part of the chapter we discuss the architecture and implementation of Videk, a prototype mashup for environmental intelligence.

Real-time news recommender system

In this demo we present a robust system for delivering real-time news recommendation to the user based on the users history of the past visits to the site, current users context and popularity of stories. Our system is running live providing real-time recommendations of news articles. The system handles overspecializing as we recommend categories as opposed to items, it implicitly uses collaboration by taking into account user context and popular items and, it can handle new users by using context information. A unique characteristic of our system is that it prefers freshness over relevance, which is important for recommending news articles in real-world setting as addressed here. We experimentally compare the proposed approach as implemented in our system against several state-of-the-art alternatives and show that it significantly outperforms them.

Advanced access architecture for efficient service delivery in heterogeneous wireless networks

For several years now the industry is promising to mobile users high QoS seamless wireless access. This promise has been kept to some extent, but the cost for services is still high. Open spectrum access is expected to lead to lower cost of bit/Hz, encourage the development of new wireless technologies and increase their market penetration. Under an open spectrum access scenario where connectivity can be achieved using several wireless technologies (cellular, WLAN, WMAN, satellite, etc.) seamless access represents the major challenge. In this paper we propose SmartA, a wireless access architecture that brings several advantages to the end user and to the network operator (NO) in the same time. The proposed wireless access architecture permits the user to benefit from the services which can be provided over a wireless infrastructure in a cost-effective way while hiding the technological complexity of the underlying system. The architecture uses cognitive network principles so that the NO can maximize its revenue using adequate policies and reduce network operation and maintenance costs.