DOI: 10.3897/jucs.152399

Authors: Abdelhady Naguib, Abdulaziz Shehab

Abstract: The importance of localization algorithms is due to their uses in various wireless sensor network applications. A single anchor movement can be used to aid in localization to reduce the cost of using multiple anchors or equipping sensor nodes with GPS units, but the main challenge here is choosing the best path of movement while avoiding potential obstacles. This paper proposes a path planning algorithm called Square Spiral with Obstacle Avoidance (SQSPOA) which allows a mobile anchor node to track an optimal path while broadcasting its current coordinates to the unknown sensor nodes. During its movement, the mobile anchor node faces many obstacles that may hinder its mobility; but as a result of the superiority of the proposed algorithm the mobile anchor can avoid these obstacles while still broadcasting its coordinates to sensor nodes. The performance of the proposed algorithm was evaluated at the presence of variable-sized obstacles and was compared with recent path planning algorithms. Simulation results proved the superiority of the proposed algorithm with respect to localization error, percent of localized sensor node and trajectory length.

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DOI: 10.3897/jucs.2020.077

Authors: Lelio Campanile, Mauro Iacono, Fiammetta Marulli, Michele Mastroianni, Nicola Mazzocca

Abstract: Technological development and market expansion offer an increased availability of resources and computing power on IoT nodes at affordable cost. The edge computing paradigm allows keeping locally on the edge of the network a part of computing, while keeping all advantages of the cloud and adding support for privacy, real-time and network resilience. This can be further improved in IoT applications by exibly harvesting resources on IoT nodes, by moving part of the computing tasks related to data from the edge server to the nodes, raising the abstraction level of the data aspects of the architecture and potentially enabling larger IoT networks to be efficiently deployed and managed, in a stand-alone logic or as a component of edge architecture. Anyway, an e_cient energy management mechanism is needed for battery powered IoT networks, the most exible implementations, that dynamically balances task allocation and execution in order to In this paper we present a fuzzy logic based power management strategy for IoT subsystem that aims at maximizing the duration of the network by locally migrating part of the computing tasks between nodes. As our goal is to enable the deployment of semi-autonomic large IoT networks, our proposal does not rely on external resources for migration control and operates on a local basis to ensure scalability: at the best of our knowledge, this differentiates our proposal with respect to similar solutions available in literature.

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DOI: 10.3897/jucs.2020.076

Authors: Łukasz Apiecionek, Matusz Biedziak

Abstract: One of huge problem for recent IT systems are attacks on their resources called Distributed Denial of Service attacks. Many servers which are accessible from public network were a victim of such attacks or could be in the future. Unfortunately, there is still no effective method for protecting network servers against source of the attack, while such attack could block network resources for many hours. Existing solutions for protecting networks and IoT systems are using mainly firewalls and IDS/IPS mechanisms, which is not sufficient. This article presents the method minimizing the DDoS attacks. Proposed method provides possibilities for the network administrators to protect their servers and IoT network resources during the attack. The proposed fuzzy adaptive algorithm is using Ordered Fuzzy Numbers for predicting amount of packets which could be passed over the network boarder gateway. Proposed solution will give the opportunity for ordinary users to finish their work when the attack occurs.

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DOI: 10.3897/jucs.2020.028

Authors: Sławomir Bujnowski, Tomasz Marciniak, Beata Marciniak, Zbigniew Lutowski

Abstract: The subject of this article is to present the results of the analysis of the possibilities to create optimal third-degree Reference Graphs which may be used to model ICT networks. The first part discusses the causes for the interest in the subject of the thesis. Basic definitions and terms related to the analysed type of graphs describing ICT networks are given. The second part consists of the analysis of the possibilities to construct regular third-degree structures bases on the usage of one ring of the parameters typical for Reference Graphs. A method of conduct is presented and then used for checking the potential possibility to construct optimal graphs. In the subsequent chapter the results of analysis of the possibilities to create optimal third-degree graphs with a double ring is discussed. The paper is concluded by observations and conclusions resulting from the research.

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DOI: 10.3217/jucs-025-07-0788

Authors: Robin Mueller-Bady, Martin Kappes, Inmaculada Medina-Bulo, Francisco Palomo-Lozano

Abstract: In this paper, the applicability of heuristic methods for an automated and reactive optimization of network infrastructures in highly-dynamic communication networks is studied. With an increasing amount of (mobile) participants and at the same time significantly growing quality requirements in communication networks over the past years, optimization of communication infrastructures will become an inevitable challenge in providing a reliable and high-quality communication service. Mostly, changes in highly-dynamic networks, which may be planned or unplanned, happen swiftly, such that it is not possible to apply manual optimization. Thus, an automated and reactive optimization becomes necessary to address this problem. Two major issues arise from the optimization of highly-dynamic communication networks. First, the complexity of problems, which is either implied by the complex optimization problem or the number of different possibly concurrent goals subject to optimization. Second, the highly-dynamic optimization search space, where network topologies may change rapidly introducing severe challenges for the optimization process. Here, different evolutionary and greedy optimization heuristics for the optimal selection of monitors in communication networks are studied and compared. Monitor selection is a well-known, important, and complex (NP-hard) optimization problem, serving as a current and actual use case for the general concept of highly-dynamic communication network optimization. As the results show, two of three methods reliably provide solutions of sufficiently high quality in reasonable time, enabling the applicability of heuristic methods of optimization in highly-dynamic communication networks. Results of the experiments are obtained using state-of-the-art statistical methods for evaluation of (evolutionary) search heuristics on a set of 39 real-world and synthetic benchmark problem instances.

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DOI: 10.3217/jucs-025-06-0591

Authors: Sławomir Bujnowski, Tomasz Marciniak, Beata Marciniak, Zbigniew Lutowski

Abstract: The paper shows the analysis of the influence of the introduction of network resources control on the transmission properties of the networks described with irregular graphs. The method developed and used by the authors in reference to regular graphs was applied. It consists in distributing the transmission resources according to specified unevenness coefficients of United States of Americage of individual edges. The way of determining these coefficients was described as well as the applied rule of distribution of the resources in case of equivalent and various density of the traffic generated by the network users. The improvement of the transmission properties of the analysed networks, understood to be the lowering of the probability of rejecting a service call resulting from the introduction of network resources control, was proved by the results of simulation research of simple and more complex network structures.

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DOI: 10.3217/jucs-025-06-0571

Authors: Łukasz Apiecionek, Marcel Großmann, Udo Krieger

Abstract: In recent years we have realized a rapid development regarding the Internet of Things (IoT). Its goal is to interconnect all possible devices to the Internet and to enhance these physical objects by new functionalities. In this way a user's life standard shall be improved. Regarding the application of Internet of Things concepts, there are some commonly known types of an IoT architecture which can provide different technical opportunities. However, comparative studies on Internet of Things architectures are rare. To relieve the difficulties of establishing a single universal IoT architecture, we describe some well-known architectures and compare these proposals with a special regard to important security aspects. A major focus is devoted to methods repulsing Denial-of-Service attacks. We compile a set of criteria that support network administrators in their decision-making processes with regard to a considered specific IoT scenario and its solution. The goal is to fit optimally to the requirements of these solutions. Finally, the proposed approach is illustrated by three already deployed IoT systems and a comparison of their related architectures and functionalities is presented.

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DOI: 10.3217/jucs-024-09-1282

Authors: Pir Shah, Peer Shah, Sadaf Yasmin, Zahoor Ur-Rehman, Akhlaque Ahmad, Yunyoung Nam, Seungmin Rho

Abstract: Content Centric Networking (CCN) is recently gaining attention for its potential to support emerging applications within Internet of Things (IoT). IoT generates huge volumes of data, with millions of nodes frequently requesting or generating different contents. CCN helps in breaking the coupling between a content and its location by addressing data with name rather than its location. This paper supports a CCN based approach in the IoT environment. To address scalability problems associated with CCN-assisted IoTs, we propose a new crumbling walls log quorum system based name resolution routing technique. The proposed system supports scalability, as the intersection property of a quorum system, inevitably minimizes the read/write operations overhead on distributed name resolution servers. Results show that the proposed technique increases the availability of the system along with low lookup overhead, latency, and load on distributed servers.

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DOI: 10.3217/jucs-024-05-0577

Authors: S. Prabavathy, K. Sundarakantham, S. Mercy Shalinie

Abstract: The rapid growth of Internet of Things(IoT) has reached all the facets of life including critical infrastructures. It has become the foundation for most of the critical infrastructures. The increased connectivity and the heterogeneity in IoT have widened the attack surface of critical infrastructures for attackers to exploit. Certain cyberattacks in critical infrastructures can lead to catastrophe and hence the attack has to be identified as early as possible to stop or reduce its impact by activating suitable responses. Therefore, the critical infrastructures require an intelligent security mechanism which can intelligently interpret the attacks from the IoT traffic and efficiently handle the attack scenario by activating appropriate response at faster rate. In this work, an autonomic security system with intelligent self-protect mechanism has been proposed for critical infrastructures. The autonomic security system can autonomously detect known attacks using Extreme Learning Machine, predict the unknown attacks using Gaussian process regression, and select suitable response for handling the attack using fuzzy logic. This intelligence of self-protect mechanism is incorporated in the distributed fog nodes to handle the attack scenario at faster rate and protect the critical infrastructures with minimal human intervention. The experimental analysis of the proposed autonomic security system proves to be efficient in detecting and defending the cyber-attacks with high accuracy and success rate. The results on network load and response time indicates the effectiveness of fog computing in proposed system.

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DOI: 10.3217/jucs-023-05-0454

Authors: Grzegorz Blinowski, Krzysztof Szczypiorski

Abstract: One of the areas in which wireless networks based on visible light communication (VLC) is considered superior to traditional radio-based communication is security. The common slogan summarizing VLC security features is WYSIWYS - "What You See Is What You Send". However, especially in the case of infrastructure downlink communication, security must be accounted for also in case of VLC. In this paper, we analyze the possibilities of implementing a steganographic channel in VLC systems on the physical (PHY) and medium access control (MAC) layers. We introduce new steganographic techniques for VLC: hiding data in dimming patterns and color visibility dimming (CVD) frames, and adapt methods previously proposed for radio networks, such as using unused header bits and pseudo-corrupted frames to hide data. We use the IEEE 802.15.7 standard as a reference model for protocol structure, but the steganographic techniques that we describe can also be used in networks based on different standards.

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DOI: 10.3217/jucs-022-07-0896

Authors: Unai Aguilera, Diego López-De-Ipiña

Abstract: Service discovery is a fundamental aspect of many services oriented applications; however, it cannot be directly applied to mobile ad hoc networks (MANET) due to their dynamic nature. The lack of central manager nodes results in the need of specific discovery solutions for this kind of networks. In this paper, we present a solution for the discovery of services in MANETs that is based on the classification of service's parameters according to a shared domain ontology. Our proposed discovery protocol encompasses two main processes: dissemination and search. The search process defines a pruning mechanism that enables to detect if search messages must be propagated or not, reducing the number of messages communicated through the network. The dissemination and search processes are integrated within the route management mechanism that enables to reduce the number of propagated messages. We have implemented and tested our discovery solution using the ns-2 network simulator. Experiments have been performed using rigorously constructed scenarios for testing the characteristics of the proposed solution. The obtained results show how the inclusion of the ontology not only increments the expressiveness of the search and discovery process, but also enables to reduce the number of propagated messages due to the grouping and pruning processes.

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DOI: 10.3217/jucs-021-12-1594

Authors: Shantanu Pal

Abstract: With the tremendous growth of mobile devices, e.g, smartphones, tablets and PDAs in recent years, people are looking for more advanced platforms in order to use their computational applications (e.g., processing and storage) in a faster and more convenient way. In addition, mobile devices are capable of using cloud-based applications and the use of such technology is growing in popularity. However, one major concern is how to efficiently access these cloud-based applications when using a resource-constraint mobile device. Because it requires a continuous Internet connection which is difficult to obtain in challenged environments that lack an infrastructure for communication (e.g., in sparse or rural areas) or areas with infrastructure (e.g., urban or high density areas) with restricted/full of interference access networks and even areas with high costs of Internet roaming. In these situations the use of opportunistic networks may be extended to avail cloud-based applications to the user. In this paper we explore the emergence of extending mobile cloud platforms using opportunistic networks. The motivation of this paper is twofold. First, we classify the available mobile cloud architectures according to their intent, the way they deliver services, and survey the state of the art research and issues related to their performance (e.g., battery power, storage capacity, bandwidth utilisation), environments (e.g., heterogeneity of networks, user's collaborations), robustness (e.g., scalability and availability of resources) and efficiency (e.g., context aware mobile services, access costs, energy consumption). Second, we devise a new `mobile-opportunistic collaborative cloud' (MoCC) architecture which enhances mobile cloud platforms using opportunistic networks. Next, we outline the open issues and future research directions that need to be improved upon for delivering a more scalable, location-aware and context based service to the users.

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DOI: 10.3217/jucs-020-13-1855

Authors: Ming Yang, Bo Liu, Wei Wang, Junzhou Luo, Xiaojun Shen

Abstract: By exploiting multi-radio multi-channel technology, wireless mesh networks can effectively provide wireless broadband access to the Internet for mobile users. Due to the limited number of orthogonal channels, overlapping channel assignment is one of the main factors that greatly affect the network capacity. However, current results in this area are not so satisfying. In this paper, we first propose a model for measuring achieved network capacity in MR-WMNs. Then we prove that finding an optimal overlapping channel assignment in a given MR-WMN with odd number of channels, is equivalent to finding an optimal assignment by only using its orthogonal channels. This theory allows us to use fewer channels to solve complicated channel assignment problems. Third, we prove that in 802.11b/g MR-WMN the simplified optimization problem is a Max-3-Cut problem. Although this problem is NP-hard, it has an efficient approximation algorithm that achieves approximation ratio of 1.19616 probabilistically by using the algorithm for Max-Cut whose approximation ratio is 1.1383 probabilistically. Based on the algorithm for Max-Cut, this paper proposes Max-Cut based channel assignment (MCCA) which uses a heuristic method to adjust the result produced by the Max-Cut algorithm to achieve an even better result. Finally, we perform extensive simulations to compare the MCCA with a state-of-the-art Tabu-Search based algorithm. The results show that the Max-Cut based overlapping channel assignment algorithm effectively and efficiently improves on the network capacity compared with existing algorithms.

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DOI: 10.3217/jucs-020-13-1738

Authors: Davide Vega, Roc Meseguer, Felix Freitag, Sergio Ochoa

Abstract: Volunteer computing is a paradigm in which devices participating in a distributed environment share part of their resources to help others perform their activities. The effectiveness of this computing paradigm depends on the collaboration attitude adopted by the participating devices. Unfortunately for software designers it is not clear how to contribute with local resources to the shared environment without compromising resources that could then be required by the contributors. Therefore, many designers adopt a conservative position when defining the collaboration strategy to be embedded in volunteer computing applications. This position produces an underutilization of the devices’ local resources and reduces the effectiveness of these solutions. This article presents a study that helps designers understand the impact of adopting a particular collaboration attitude to contribute with local resources to the distributed shared environment. The study considers five collaboration strategies, which are analyzed in computing environments with both, abundance and scarcity of resources. The obtained results indicate that collaboration strategies based on effort-based incentives work better than those using contribution-based incentives. These results also show that the use of effort-based incentives does not jeopardize the availability of local resources for the local needs.

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DOI: 10.3217/jucs-019-16-2437

Authors: Giuseppe Cattaneo, Giancarlo Maio, Umberto Petrillo

Abstract: The Global Systems for Mobile communications (GSM) is actually the most widespread mobile communication technology existing nowadays. Despite being a mature technology, its introduction dates back to the late eighties, it suffers from several security vulnerabilities, which have been targeted by many attacks aimed to break the underlying communication protocol. Most of these attacks focuses on the A5/1 algorithm used to protect over-the-air communication between the two parties of a phone call. This algorithm has been superseded by new and more secure algorithms. However, it is still in use in the GSM networks as a fallback option, thus still putting at risk the security of the GSM based conversations. The objective of this work is to review some of the most relevant results in this field and discuss their practical feasibility. To this end, we consider not only the contributions coming from the canonical scientific literature but also those that have been proposed in a more informal context, such as during hacker conferences.

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DOI: 10.3217/jucs-018-12-1643

Authors: Pedro Martinez-Julia, Antonio Skarmeta

Abstract: In this paper we show a network architecture for Next Generation Internet (NGI) that prevents operation traceability and protects the privacy of communication parties while raising their identity to be a central element of the network. As a side effect, our architecture inherently supports authentication and mobility of the entities involved in the communication. Moreover, it is designed to be agnostic to any underlying network infrastructure and can be used to enhance them with reduced penalty, which makes it a perfect component to take its features to existing networks without defining a brand new transport layer. We also show the successful verification of the protocol security and demonstrate its feasibility and scalability showing its behavior when instantiated on top of two different architectures.

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DOI: 10.3217/jucs-018-09-1194

Authors: Qiang Liu, Min Chen, Jie Zhang, Bingwen Shen, Zhong Chu

Abstract: In this paper, a novel network planning process of the Mobile WiMAX for Railway (WiMAX-R) network is proposed. We first analyze the factors need considered in network planning. After introducing the WiMAX-R network architecture, the WiMAX-R network planning process is presented in detail. The process comprises application analysis, capacity prediction, network parameters configuring, coverage planning, handover planning and network simulation validation. In each step, Mobile WiMAX technical features and railway environment characters are both take into consideration. Finally, we simulated a WiMAX-R planning example based on OPNET platform. The simulation results showed that the designed WiMAX-R network can perfectly satisfy the applications’ QoS requirements.

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DOI: 10.3217/jucs-018-06-0857

Authors: Jezabel Molina-Gil, Pino Caballero-Gil, Cándido Caballero-Gil

Abstract: A key aspect to ensure that Vehicular Ad-hoc NETworks (VANETS) work properly is the provision of reliable and real time information to users. In order to achieve this goal, on the one hand, nodes must cooperate actively in relaying the messages to reach as many users as possible to warn them about possible hazards. On the other hand, users should be able to rely on the received information, so they should be able to verify that the relayed network data are true. As distributed and decentralized networks, security problems such as prevention of false information injection, and detection of misbehaviour could be solved through cooperation among nodes. In this work we propose a set of countermeasures to prevent selfish behaviour and malicious attacks, making use of node revocation through cooperation enforcement mechanisms and isolation of malicious nodes from the network. The proper performance of the proposed techniques has been evaluated with many simulations, and the results show that the countermeasures described in this work increase not only efficiency but also security of communications.

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DOI: 10.3217/jucs-018-05-0599

Authors: Grzegorz Chmaj, Krzysztof Walkowiak

Abstract: Peer-to-Peer (P2P) computing (also called 'public-resource computing') is an effective approach to perform computation of large tasks. Currently used P2P computing systems (e.g., BOINC) are most often centrally managed, i.e., the final result of computations is created at a central node using partial results - what may be not efficient in the case when numerous participants are willing to download the final result. In this paper, we propose a novel approach to P2P computing systems. We assume that results can be delivered to all peers in a distributed way using three types of network flows: unicast, Peer-to-Peer and anycast. We describe our concept of the system architecture with a special focus on the decision strategies developed for system participants. Using our discrete realtime simulator we evaluate the proposed strategies in various scenarios and present a comprehensive analysis of obtained results. According to obtained results, the Peer-to-Peer flow provides lower operational cost of the computing system compared to unicast and anycast flows. Moreover, an appropriate selection of decision strategy can significantly reduce the operational cost.

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DOI: 10.3217/jucs-017-14-2064

Authors: Junzhou Luo, Wenjia Wu, Ming Yang

Abstract: In a wireless mesh network (WMN), gateways act as the bridges between the mesh backbone and the Internet, and significantly affect the performance of the whole network. Hence, how to determine the optimal number and positions of gateways, i.e., gateway deployment, is one of the most important and challenging topics in practical and theoretical research on designing a WMN. Although several approaches have been proposed to address this problem, few of them take load balancing and interference minimization into account. In this paper, we study the Load-balancing and Interference-minimization Gateway Deployment Problem (LIGDP), which aims to achieve four objectives, i.e. minimizing deployment cost, minimizing MR-GW path length, balancing gateway load and minimizing link interference. We formulate it as a multi-objective integer linear program (ILP) issue first, and then propose an efficient gateway deployment approach, called LIGDP Heuristic. The approach joints two heuristic algorithms, i.e., MSC-based location algorithm (MLA) and load-aware and interference-aware association algorithm (LIAA), to determine gateway positions and construct GW-rooted trees. Simulation results not only show that the trade-off between deployment cost and network performance can be achieved by adjusting R-hop, GW throughput and MR throughput constraints, but also demonstrate that, compared with other existing approaches, LIGDP Heuristic performs better on MR-GW path, load balancing and interference minimization without deploying more gateways.

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DOI: 10.3217/jucs-017-11-1605

Authors: Khaled Salah, Mojeeb-Al-Rhman Al-Khiaty, Rashad Ahmed, Adnan Mahdi

Abstract: Snort is the most widely deployed network intrusion detection system (NIDS) worldwide, with millions of downloads to date. PC-based Snort typically runs on either Linux or Windows operating systems. In this paper, we present an experimental evaluation and comparison of the performance of Snort NIDS when running under the two newly released operating systems of Windows 7 and Windows Server 2008. Snort's performance is measured when subjecting a PC host running Snort to both normal and malicious traffic. Snort's performance is evaluated and compared in terms of throughput and packet loss. In order to offer sound interpretations and get a better insight into the behaviour of Snort, we also measure the packet loss encountered at the kernel level. In addition, we study the impact of running Snort under different system configurations which include CPU scheduling priority given to user applications or kernel services, uni and multiprocessor environment, and processor affinity.

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DOI: 10.3217/jucs-017-08-1202

Authors: Hajar Mousannif, Ismail Khalil, Hassan Moatassime

Abstract: Vehicular Networks, including Vehicular Adhoc Networks (VANETs) and Vehicular Sensor Networks (VSNs), stimulate a brand new variety of services, ranging from driver safety services, traffic information and warnings regarding traffic jams and accidents, to providing weather or road condition, parking availability, and advertisement. 3G networks and sophisticated Intelligent Transportation Systems (ITS), including deploying costly roadside base stations, can indeed be used to offer such services, but these come with a cost, both at network and hardware levels. In this paper we introduce Cooperation as a service (CaaS): A novel architecture that will allow providing a set of services for free and without any additional infrastructure, by taking advantage of Vehicle-to-Vehicle communications. CaaS uses a hybrid publish/subscribe mechanism where the driver (or subscriber) expresses his interests regarding a service (or a set of services) and where cars having subscribed to the same service will cooperate to provide the subscriber with the necessary information regarding the service he subscribed to, by publishing this information in the network. CaaS structures the network into clusters, and uses Content Based Routing (CBR) for intra-cluster communications and geographic routing for inter-cluster communications.

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DOI: 10.3217/jucs-016-21-3299

Authors: Khaled Salah, Mohamed Hamawi

Abstract: These days, commodity-off-the-shelf (COTS) hardware and software are used to build high-end and powerful workstations and servers to be deployed in today's local area networks of private homes and small- to medium-sized business. Typically, these servers are multipurpose and shared - running networking functionalities involving IP packet forwarding in addition to other CPU intensive applications. In this paper we study and investigate the impact of running CPU-bound applications on the performance of IP packet forwarding. We measure and compare the impact and performance for the two operating systems of choice for home and small-business users, namely Linux and Windows XP. The performance is studied in terms of key performance metrics which include throughput, packet loss, round-trip delay, and CPU availability. For our measurements, we consider today's typical home network hosts of modern processors and Gigabit network cards. We also consider different configuration setups and utilize open-source tools to generate relatively high traffic rates. Our empirical results show that Linux exhibits superior performance over Windows XP in terms of IP forwarding performance. Results also show that, unlike Windows XP, the IP forwarding performance of Linux is not significantly impacted by running CPU-bound applications.

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DOI: 10.3217/jucs-016-15-1973

Authors: Carlos Baladrón, Alejandro Cadenas, Javier Aguiar, Belén Carro, Antonio Sánchez-Esguevillas

Abstract: Telco operators and other players are searching for intelligent value-added services, i.e., communication applications that take advantage of the huge amount of user data available to the operators (location, contact lists, etc.) in order to adapt themselves to the preferences and context of each individual. However, the current networks of the operators lack the proper infrastructure to handle context data in a clean and unified way, so smart context-aware applications are extremely difficult to engineer, develop and deploy. Accordingly in this paper a global context processing architecture is presented. In addition, the monitoring of users in order to extract and process the context is a task potentially resource consuming. That is a significant problem in global telco deployments.This paper also presents a proposal for a multi-level context management framework for smart telecommunications services, whose objective is to optimise the available processing resources of the presented architecture to provide contextual monitoring to a high number of subscribers with limited resources.

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DOI: 10.3217/jucs-016-12-1592

Authors: Lidia Fuentes, Nadia Gámez

Abstract: Developing Ambient Intelligence applications is a very complex task since it implies dealing with low-level software and hardware resources. The use of a middleware platform may alleviate this task by providing a set of high-level and platform-independent services to these kinds of applications. Nevertheless, the tendency is that the middleware deployed in each device has a flat and homogeneous architecture, although these devices and the requirements of intelligence environments are heterogeneous. This implies the middleware software deployed in each device normally contains more functionality than strictly required, leading to waste resources so scarce in lightweight devices. But the configuration and deployment of a minimal middleware customized to a target platform is a complex task, due to the diversity of hardware and software present in devices and the variable requirements of ambient intelligence applications. In order to solve these shortcomings, we propose to customize the piece of software related to the middleware platform by using a Software Product Line engineering approach. This paper presents an innovative configuration process for a software product line for ambient intelligence middleware where a minimal set of high-level parameters needs to be specified. So, the software engineers for this kind of systems can automatically obtain customized middleware by simply specifying this high-level information.

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DOI: 10.3217/jucs-016-10-1343

Authors: Lei Shu, Manfred Hauswirth, Yan Zhang, Jianhua Ma, Geyong Min, Yu Wang

Abstract: The use of multimedia sensor nodes can significantly enhance the capability of wireless sensor networks (WSNs) for event description. In a number of scenarios, e.g., an erupting volcano, the WSNs are not deployed to work for an extremely long time. Instead, the WSNs aim to deliver continuous and reliable multimedia data as much as possible within an expected lifetime. In this paper, we focus on the efficient gathering of multimedia data in WSNs within an expected lifetime. An adaptive scheme to dynamically adjust the transmission Radius and data generation Rate Adjustment (RRA) is proposed based on a cross layer design by considering the interaction among physical, network and transport layers. We first minimize the end-to-end transmission delay in WSNs while using the minimum data generation rate. In this phase, an optimal transmission radius can be derived. Then, using this transmission radius, we adaptively adjust the data generation rate to increase the amount of gathered data. Simulation results show that the proposed RRA strategy can effectively enhance the data gathering performance in wireless multimedia sensor networks (WMSNs) by dynamically adjusting the transmission radius of sensor nodes and the data generation rate of source nodes.

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DOI: 10.3217/jucs-015-14-2747

Authors: Carlos Aguirre, Ramon Huerta, Lev Tsimring

Abstract: A network attack is a set of network elements that are disabled by an adversary. The goal for the attack is to produce the most possible damage to the network in terms of network connectivity by disabling the least possible number of network elements. We show that the problem of finding the optimal attack in a serverless network is NP-Complete even when only edges or nodes are considered for disabling. We study a node attack policy with polynomial complexity based on shorter paths and show that this attack policy outperforms in most cases classical attacks policies such as random attack or maximum degree attack. We also study the behavior of different network topologies under these attack policies.

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DOI: 10.3217/jucs-014-07-1105

Authors: SungSoo Lee, HangKon Kim, ChongGun Kim

Abstract: A central characteristic of ad hoc mobile networks is the frequent changes of their topology. This is the source of many problems that need to be solved. AODV is an on-demand routing protocol for decreasing maintenance overhead in ad hoc networks. However, some path breaks can cause significant overhead and transmission delays. If the maintenance overhead of the ro uting table can be reduced, table -driven routing methods could be an efficient substitution. In this paper , we propose a knowledge discovery agent for an effective routing method that uses simple bit -map topology information. The agent node gathers topology knowledge and creates topology bit -map information. All available paths from a source to a destination can easily be calculate d using the bit-map. All the nodes in the network maintain the bit-map distributed from the agent, and use it for the source of routing. The performance and the correctness of the proposed agent method is verified by computer simulations.

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DOI: 10.3217/jucs-014-05-0731

Authors: Alberto Garcia, Klaus Hackbarth

Abstract: This article provides a comparison among different methods for estimating the aggregation of Internet traffic resulting from different users, network-access types and corresponding services. Some approximate models usually used as isolated methods are combined with a temporally scaled ON-OFF model with binomial approximations. The aggregation problem is solved using a new form of parameterization based on the composition of the source traffic accordingly to the concrete characteristics of the users, the accesses and the services. This is a new concept, called CASUAL, included within an overall network planning methodology for the design and dimensioning of Next Generation Internet.

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DOI: 10.3217/jucs-014-05-0653

Authors: Laura De Lope, Klaus Hackbarth

Abstract: The European Regulator Gr oup (ERG) defines Bitstream Access Service as a wholesale service offered by a broadband network operator with significant market power to an Internet Service Provider , and identifies it as a market subje ct to regulation. This paper develops a cost model f or the Bitstream Access Service under xDSL technology, following the recommendations of the ERG , considering different user classes with differentiated QoS requirements. For this purpose, three traffic engineering methods are analysed: separate virtual tunnels, over-engineering and priority queuing techniques.

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DOI: 10.3217/jucs-014-05-0642

Authors: Wojciech Stańczuk, Józef Lubacz, Eugeniusz Toczyłowski

Abstract: This paper presents a novel market model for balancing communication bandwidth trade. The distinguishing characteristic of the model is that it assumes that market players can place buy offers not only for isolated network resources (inter-node links), but also for end-to-end network paths of predefined capacity. It also enables effective balancing of sell and buy offers for network resources in such a way which maximizes the global economic welfare. From a formal point of view, the model produces a linear programming problem for clearing a multi-commodity market. Three simple examples are used to discuss and illustrate the proposed model.

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DOI: 10.3217/jucs-013-01-0056

Authors: Dang-Quan Nguyen, Pascale Minet

Abstract: Ad hoc wireless networks have enormous commercial and military potential becauseof their self-organizing capacity and mobility support. However, some specificities of these networks such as radio interferences and limited resources make more complex the quality of service(QoS) support. Indeed, on the one hand, the bandwidth offered to users is strongly affected by radio interferences. On the other hand, flooding information in such a network must be optimizedin order to save resources. Therefore, we propose in this paper, a solution taking into account radio interferences in mobile ad hoc network routing and optimizing flooding. This solution isbased on a modified version of the OLSR routing protocol that considers bandwidth requests and radio interferences in the route selection process while providing a very efficient flooding.A comparative performance evaluation based on NS simulations shows that despite the overhead due to QoS management, this solution outperforms classical OLSR in terms of QoS perceivedby the users (e.g. bandwidth amount granted to a flow and delivery rate). The efficiency of the optimized flooding is equal to that provided by the native version of OLSR.

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DOI: 10.3217/jucs-013-01-0004

Authors: Saadi Boudjit, Cédric Adjih, Paul Mühlethaler, Anis Laouiti

Abstract: Mobile Ad hoc NETworks (MANETs) are infrastructure-free, highly dynamic wireless networks, where central administration or configuration by the user is very difficult. In hardwired networks nodes usually rely on a centralized server and use a dynamic host configuration protocol, like DHCP [Droms et al. 2003], to acquire an IP address. Such a solution cannot be deployed in MANETs due to the unavailability of any centralized DHCP server. For small scale MANETs, it may be possible to allocate free IP addresses manually. However, the procedure becomes impractical for a large-scale or open system where mobile nodes are free to join and leave.

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DOI: 10.3217/jucs-011-04-0495

Authors: Tomaso Forzi, Meikel Peters

Abstract: A well-functioning Knowledge Management is a competitive advantage for enterprises that act in co-operative and distributed networks with knowledge intensive production processes. A Knowledge Management approach that integrates both, hard factors (e.g. Information Technology) and soft factors (e.g., cultural aspects) for distributed and dynamic entrepreneurial (inter-organisational) networks is currently missing. This paper presents research findings of a project that is developing a methodology as well as an appropriate toolkit to support a service provider responsible for the KM within distributed entrepreneurial networks. The project integrates explicitly both new Information and Communication Technology driven organisational concepts, human-oriented approaches and existing KM methodologies and instruments.

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DOI: 10.3217/jucs-003-12-1382

Authors: Uwe Glaesser, Rene Karges

Abstract: Based on the ITU-T Recommendation Z.100 [27]---also known as SDL-92--- we define a formal semantic model of the dynamic properties of Basic SDL in terms of an abstract SDL machine. More precisely, we use the concept of multi-agent realtime ASM [17] as a semantic platform on top of which we construct our mathematical description. The resulting interpretation model is not only mathematically precise but also reflects the common understanding of SDL in a direct and intuitive manner; it provides a concise and understandable representation of the complete dynamic semantics of Basic SDL. Moreover, the model can easily be extended and modified---a particularly important issue for an evolving technical standard. In this article, we consider all relevant aspects concerning the behavior of channels, processes and timers with respect to signal transfer operations and timer operations. The model we obtain is intended as a basis for formal documentation as well as for executable high-level SDL specifications.

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DOI: 10.3217/jucs-001-01-0023

Authors: Ville Leppänen

Abstract: We show how to implement an -processor EREW PRAM workoptimally on a 2-dimensional n-sided mesh of trees, consisting of n processors, n memory modules, and nodes. Similarly, we prove that an -processor EREW PRAM can be implemented work-optimally on a 3-dimensional n-sided mesh of trees. By the work-optimality of implementations we mean that the expected routing time of PRAM memory requests is per simulated PRAM processor with high probability. Experiments show that on relatively small and the cost per simulated PRAM processor is 1.5-2.5 in the 2-dimensional case, and 2-3 in the 3-dimensional case. If at each step at most 1/3'th of the PRAM processors make a reference to the shared memory, then the simulation cost is approximately 1. We also compare our work-optimal simulations to those proposed for coated meshes.

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