Information and Communication Technologies

Recently, the IEEE published the 802.11s standard amendment for wireless mesh networks using IEEE 802.11 hardware. Since most of the new techniques may be implemented in software, this allows to bring the benefits of mesh networking to a broad market of about one billion devices. The standard amendment describes new power save schemes which allow efficient energy saving for all mesh nodes. On the downside, the power save schemes will also degrade the network performance in terms of delay and throughput. In this paper we present a testbed analysis of the effects of 802.11s power save on mesh link performance. We analyze the effects on round-trip time and throughput in detail for different configurations and network parameters.

The performance of multi-hop wireless networks can be substantially improved by using smart antennas. However, the utilization of smart antennas is quite challenging as the benefit of the different transmission modes strongly depends on specific channel conditions. In this paper we present a novel path selection protocol PSPSA (path selection protocol for smart antennas) and a modified MAC protocol that exploits the benefits of smart antennas. PSPSA selects an optimum path considering the specific ranges and transmission rates implied by the different transmission schemes (spatial multiplexing and beamforming). The MAC protocol is a modification of the traditional DCF scheme to cope with the different PHY layer transmission schemes. Our solution enables mesh nodes to dynamically select their transmission scheme on a per packet basis according to the current channel conditions. Simulation results show that the overall packet success rate (throughput) of multi-hop wireless networks are substantially improved.

Wireless Sensor Networks (WSNs) are networks formed by highly constrained devices that communicate measured environmental data using low-power wireless transmissions. The increase of spectrum utilization in non-licensed bands along with the reduced power used by these nodes is expected to cause high interference problems in WSNs. Therefore, the design of new dynamic spectrum access techniques specifically tailored to these networks plays an important role for their future development. This work aims to provide insights into the performance of two well-known low energy-consuming Medium Access Control (MAC) techniques for WSNs (the receiver-initiated and the short-preamble burst), adapted to work with multiple channels. The results obtained show the best working conditions for each approach.

White Spaces in the UHF bands are very interesting because of their potential use in rural communications, but their feasibility needs to be proven. This paper analyses the TV spectrum occupation in the region of Catalonia, Spain, because it will be one of the first EU regions where changes in the UHF band are going to be implemented. Those changes are derived from the implementation of the Digital Dividend. The goal of this paper is to correlate population density with future free channel availability, and to proof that communications through TV White Spaces equipment is a good candidate for low density population areas.

Current virtualization technologies enable hosting of a large number of Virtual Machines (VMs) on a common physical host. The hypervisor interconnects these VMs via Virtual Networks (VNs). These VNs underlie the same security requirements as physical networks. Network elements such as stateful firewalls contribute in enforcing this security. With the advent of stateful firewalls on the hypervisor level, a new challenge arises when it comes to VM migration. Not only the VM itself, but also the associated Security Context (SC) has to migrate. Current open-source hypervisors do not address this issue. In this paper we present the architecture and implementation of our framework for migrating SC along with VMs.

The two important problems of collaborative intrusion detection are aggregation and correlation of intrusion events. The enormous amount of data generated by detection probes requires significant network and computational capacity to be processed. In this article we show that a distributed hash table based approach can reduce both network and computational load of intrusion detection, while providing almost the same accuracy of detection as centralized solutions. The efficiency of data storage can be improved by selecting Kademlia as the underlying overlay network topology, as its routing can easily adapt to the dynamic properties of such an application.

The interconnection of building automation and control system networks to public networks has exposed them to a wide range of security problems. This paper provides an overview of the flow data usability to detect security issue in these networks. The flow-based monitoring inside automation and control networks is a novel approach. In this paper, we describe several use cases in which flow monitoring provides information on network activities in building automation and control systems. We demonstrate a detection of Telnet brute force attacks, access control validation and targeted attacks on building automation system network.

In the last decade RFID technology has become widespread. It can be found in various fields of our daily life. Due to the rapid development more and more security problems were raised. Since tags have limited memory and very low computational capacity a so-called lightweight authentication is needed. Several protocols have been proposed to resolve security and privacy issues in RFID systems. However, the earlier suggested algorithms do not satisfy all of the security requirements.

In this paper we introduce our hash-based mutual authentication protocol which meets all the security requirements. Our solution provides an efficient mutual authentication method. Our protocol can defy the well-known attacks and does not demand high computational capacity.

In this paper we discuss the impact the use of IPv6 has on remote penetration testing of servers and web applications. Several modifications to the penetration testing process are proposed to accommodate IPv6. Among these modifications are ways of performing fragmentation attacks, host discovery and brute-force protection. We also propose new checks for IPv6-specific vulnerabilities, such as bypassing firewalls using extension headers and reaching internal hosts through available transition mechanisms.

The changes to the penetration testing process proposed in this paper can be used by security companies to make their penetration testing process applicable to IPv6 targets.

Telecommunication services are widespread and subject today to tensions on a competitive market. Telecommunication service design is more and more software oriented. To reduce time to market and cost of services, a service designer better need to simulate and evaluate his design earlier. The approach proposed in this paper is to reduce the abstraction gap between modeling and simulation phases using model transformation. But manual transformations are so far time consuming and error prone. As a trustworthy solution, model based techniques and associated transformations permit to systematically link service models with simulation phase before realization. We thus propose as a first contribution a meta-model dedicated to concepts of IP Multimedia Subsystem core network as a case study. Our meta-model constrains and defines such network entities to be used in the code generation, which is our second contribution. The implementation of a video conference service permits to illustrate our workbench.

This paper introduces the problem of communication network migration for backbone networks. Heuristic solutions for this problem can be determined by the application of genetic algorithms to the problem. A description of the system model is presented, as well as the used algorithmic approaches and optimization results. Our main goal is the optimization of migration costs, by respecting increasing demands over the migration period, while device costs per bit are decreasing. We will present Crowded DPGA as best found GA to solve the network migration problem.

Node capability parameter configuration is the validation and settings of node capability parameter values according to node capability parameter configuration specification (CapSpc). A node capability is a property of a node required as basis for service implementation. This paper presents a Node Capability Parameter Configuration System (CapCon). Node Capability Ontology (CapOnt) is the basis for CapCon. This paper has focus on CapCon in network management. CapSpc specifies required types, parameters, and parameter values for the node capabilities. OWL and OWL/XDD are used to represent the ontology concepts. The NETCONF framework is applied for the network management functionality. A prototype implementation and a case study including experimental results are presented.

The present paper compares, from a techno-economic point of view, two currently available access network solutions (Digital Subscriber Line and Passive Optical Network). It also considers Long-Reach Optical Access, which augments the span of the access network. All potential solutions are evaluated on the basis of Payback Period, Net Present Value and Internal Rate of Return. The market is segmented in different areas depending on their respective households density, and various business models are considered, in order to assess the impact of public funding. The French market is shown to be the most demanding in Europe, due to its low broadband access tariffs. The paper shows that, unless the take up rate for optical access significantly increases beyond its actual value, the profitability of deploying optical access for the network operators is low.

Most federations across the world apply Single Sign-On (SSO) Authentication and Authorization Infrastructure (AAI) platforms. Thus, access to services offered by organizations, which belong to such a federation, can be granted to their users independent of their current location. The increasing demand to charge users for those service usages lead organizations to establish various charging mechanisms. However, until today the majority of organizations is using service-dependent solutions to perform charging. This policy absorbs the utility of an SSO system, since users still have to monitor and control each credit account separately. Therefore, the approach proposed defines an extension to SSO platforms, which is consolidated, non dispersed and service-independent. A Single Funding Point Charging Architecture (SFP-CA) allows users to settle payments using funds from the same credit account, for any type of service they use inside their federation.

Worldwide Interoperability for Microwave Access (WiMAX) based on the IEEE 802.16-2009 standard is a serious competitor of Long Term Evolution (LTE) for cellular networks providing high data rates to mobile users. To support various multimedia applications the Quality of Service (QoS) support is a crucial function. While the IEEE 802.16- 2009 standard defines five service classes to support the QoS requirements of various multimedia applications, the algorithms and especially the scheduling algorithms to enforce these requirements have not been specified for vendor differentiation. We propose a scheduling algorithm allocating resources according to the guaranteed and sustained rates of each connection, in contrast to common two layer scheduling approaches differentiating between service classes. Simulation results show that our scheduler is able to fulfill the QoS requirements of connections defined by the IEEE 802.16 standard.

Multipath TCP (MPTCP) is an experimental protocol currently under standardization in the IETF. MPTCP allows to use multiple TCP connections for one data transmission if at least one of the endpoints is multi-homed. For example, this can be a mobile device with a Wifi and a 3G interface. It is assumed that the paths are disjoint or partly disjoint. As such these paths have different transmission characteristics, like speed or delay. With MPTCP the congestion control of each single TCP transmission is coupled in such a way that the transmission data is distributed over all subpaths depending on the load situation on each path. In this paper, we present our implementation of the MPTCP congestion control algorithm in the Linux kernel. We evaluated, based on simulations that use the real Linux kernel implementation, if the intended goals on resource pooling and sharing could be reached.

This paper presents an analysis of a suggested method for improving fairness among competing adaptive HTTP video streams. The metrics used as fairness indicators are differences in achieved average rate and stability among the competing streams. The method analyzed is based on changing a fixed and equal video segment request rate of each stream, to either a per session unique or random request rate. The analysis is done by means of measurements in a controlled environment using the Microsoft Smooth Streaming solution. The findings are considered very positive as they show that it is possible to achieve a significant improvement in fairness by applying the suggested method. The main novelty of the paper is that it demonstrates the potential of achieving such improvements without modifying either client or server algorithms.

Advertising servers play an important role in the entire contrary e-business. In this paper an approach for a high performance ad server is proposed. A prototype of a new architecture is presented: system achieving scalability by multiplication of ad servers with separate local memory storage and single managing server for entire cluster of those, providing data processing and ads preparation.

The paper includes benchmarks of alternate technologies possible at the design stage, results of the stress tests of the prototype, as well as the data from its performance with real web traffic. Limitations of the proposed solution are discussed. Although the prototype is created on a specific platform, all technologies used are widely available or have replacements on other platforms, granting generality to the proposed solution.

There is no effective method to support IP level Internet wide multisource multicast sessions, that can be easily used from almost every ISP There are several protocols implementing the necessary functionality, but the penetration of them is really low recently. The most obvious work all-round is using SSM – Source Specific Multicasting, in which, the IP multicast session is identified by the multicast group address and the source’s unicast IP address. SSM allows using all the SSM address range for every source IP addresses and limits the address allocation problem inside the host of the source; however, its significant drawback is that the SSM has no native support to create multicast sessions with more than one source; it uses separate source specific distribution trees for every single source therefore it needs more resources on the router side. The alternative solution for supporting multisource multicast session is the ASM – Any Source Multicasting. However, its significant drawback is the lack of Internet wide dynamic address allocation. To address the recent problems of the Internet wide multisource multicast session a novel IP multicast service model, the Responsible Source Multicasting - RSM is introduced in this paper. RSM uses shared distribution trees like ASM; however, builds a reverse path tree towards an appropriate well-known unicast IP address like SSM. The paper demonstrates that this novel multicast routing protocol handles Internet wide multisource multicast sessions. The paper also shortly presents the DAMA – Dynamic Address Allocation of Multicast Addresses protocol for dynamic multicast IP address allocation, which works in a strong collaboration with the RSM.

Middleware has become a key element in the development of distributed Cyber Physical Systems (CPS). Such systems often have strict non-functional requirements, and designers need a means to predict and manage non-functional properties. In this work, the authors present a mathematical model for the most relevant resources managed by FTT middleware architectures; namely, (1) processor, (2) memory, (3) energy and (4) network. This model can be used both off-line for simulation and designing purposes of a Cyber Physical System (CPS), or in run-time within an admission test or inside the algorithm of a specific scheduling policy executed by the middleware. In such case, the admission test is aimed at predicting whether a system fulfils the non-functional requirements or not before carrying out any modification in its execution plan at run-time.

This paper focuses on survivability modeling to characterize the transient behavior of an infrastructure-based wireless network in the presence of disastrous failures and repairs. Two modeling approaches, an exact model and an approximate product-form model are presented. Numerical experiments with the two models demonstrates that the approximative product-form approach obtain close to exact results with a significant lower computational complexity. The product-form approach has been applied to study the impact of various system parameters on the survivability of the studied network.

The relay encoder is an unreliable probabilistic device which is aimed at helping the communication between the sender and the receiver. In this work we show that in the quantum setting the probabilistic behavior can be completely eliminated. We also show how to combine quantum polar encoding with superactivation-assistance in order to achieve private communication over noisy quantum relay channels.

In this paper we present a distributed algorithm, which enables to follow and surround moving objects by a swarm of homogenous robots that only use local sensing. We introduce the multi orbit surrounding problem and present a solution for it. We prove that our solution always guarantees that the robots enclose the target and circulate around them. We also evaluate our solution by simulations.

High quality and ubiquitous Internet access is a key feature of today’s mobile systems such as LTE. While LTE can provide competitive peak data rates and a relatively low latency, there is still room for solutions improving end-users’ Quality-of-Experience by optimizing services running over the LTE infrastructure. Being the most widespread transport protocol, TCP is in the main focus of such research projects. A widely recommended solution for TCP performance improvement is the split connection TCP proxy that divides the end-to-end TCP connection into two independent connections, that results increased throughput and faster error recovery. This paper investigates the performance of a split connection TCP proxy deployed in LTE’s SAE-GW. Numerical results show significant performance improvement of file downloading, web browsing and video steaming applications in case of not congested transport networks.

Fire fighters often work in dangerous and dynamic environments, which results in frequent change of network topologies and routing requirements. While the existing routing protocols are not able to cope with such a changeable environment, this paper proposes a self adaptive hybrid routing algorithm. This routing algorithm can switch between the proactive routing algorithm and reactive routing algorithm for each node pair automatically. An analytical model is created to describe the routing switch decision making algorithm. This model is based on a set of the cost functions. A numerical example shows the necessity of switching routing algorithms to reduce the overall control message overhead.

The current Internet architecture was designed more than 30 years ago for a very different set of services than those used today. Several new architectures have been proposed for a Future Internet to better meet todays and future requirements. Content Centric Networking (CCN) is one of those new architectures gaining worldwide attention by researchers and the focus of this article. CCN is based on naming content instead of hosts allowing routers to cache popular content. It has been shown that CCN can also support point-to-point real-time conversations, for example voice or video calls. However, it has not been defined how node mobility can be achieved in such a real-time scenario with strong time constraints. In this paper a close study to the handover algorithms has been carried out. A handover decision maker, which is based on neuro-fuzzy system (NFS) is proposed and evaluated. The results show that the proposed decision maker meets the design targets.

To implement a maintenance free and reliable sensor network is necessary in complex sensor systems nowadays. There are studies, which can control developers, who want to build an autonomous sensor network in a dynamically changing environment. The existing solutions have several drawbacks because of the diversity and complexity of the wireless type sensor networks. This paper introduces a sensor network architecture model, which is a good base to implement a simulation environment for the systems before implementing them. The introduced features make the possibility to fine-tune the operational parameters during the planning phase. In this way, the presented sensor network architecture is working based on the presented roles to provide its services.

In this paper we describe an efficient way of implementing multi hop broadcast in ad hoc mobile networks with an online, distributed machine intelligence solution. In our solution not just the runtime parameters of predefined protocols are optimized, but the decision logic itself also emerges dynamically. The model is based on genetic programming and natural selection: sucessive generations of protocol instances are produced to approximate optimal performance by picking certain instances from the previous generation (natural selection) and combining them with each other and/or mutating (genetic operators) them. We implemented (i) a genetic programming language to describe protocols, and (ii) defined a distributed, communication-wise non-intensive, stigmergic feed-forward evaluation and selection mechanism over protocol instances, and (iii) a budget based fair execution model for competing protocols. The results indicate that online, autonomous protocol evolution outperforms traditional approaches, by adapting to the situation at hand, when used for the multi-hop broadcast problem in ad hoc mobile networks. The evolution also protected the system from the negative effects of initially present harmful protocols.

In various network tests we often need to use different trace files in order to get the most comprehensive result. This procedure requires multiple input files which were generated in different ways. In this paper we suggest a method for analyzing a traffic measurement and extracting the most typical user behaviors. We introduce the Traffic Descriptive Strings (TDS) which is a projection of measurement data. We present an algorithm which is able to score the similarities between two TDSs.

Web services standards were designed to enable interoperability of heterogeneous application servers in the Service Oriented Architecture. Although the standards proved to be highly successful, there are still difficulties in effective services integration. The paper presents a methodology that enables description of application servers interoperability in order to improve the service integration process. The methodology proposes a systematic classification of Web services standards, versions and configuration options, and uses the classification for interoperability rating. Concrete integrations are rated by developers that specify integration scope, configuration complexity and required expertise level. The methodology was implemented in a web system that enables definition of standards and configuration options as well as rating of integrations. As a part of the research, interoperability experiments were executed and registered in the system.

Multimedia streams have increased dramatically over the wireless networks during the last few years. 3D video stream-based applications and movies will become significant contents of wireless network traffic in future Internet. This paper shows Quality of Experience (QoE) results based on transport network’s Quality of Service (QoS) level degradation obtained from subjective tests which were carried out for 3D stereoscopic video files transporting through GPON-based transport network combined with IEEE802.11n standard based WiFi sub-networks on clients’ side. Gathered information show that QoE level is influenced with more factors like: bandwidth limitation or channel interference in WiFi network and QoS parameters’ values of transport network as well. In case of 3D contents quality of film shooting, size and resolution value of using display also take effect on perceived visual quality. Evaluation results were processed statistically IBM SPSS Statistics software-package.

Wireless indoor positioning has been a popular research topic for years because it provides the basis for a broad domain of location-based applications. Especially the usage of WLAN (Wireless Local Area Network) technology is widespread to build an indoor positioning system due to the reuse of existing and almost ubiquitous WLAN infrastructure worldwide lowering the costs. However, these WLAN systems were not originally designed for positioning services, thus the provided accuracy might be low. The accuracy can be increased by the careful placement of WLAN access points to cover the given area appropriately. In this paper, we propose a method based on simulated annealing to find the optimal number and placement of WLAN access points for indoor positioning and show its investigation using simulations.

Internet traffic is continuously growing and contributes substantially to rising costs for network operators. Evaluations have shown that today multimedia content accounts for a major part of the transferred bytes in the Internet and that HTTP is the dominant protocol. A natural solution for reducing these network costs is caching of frequently requested content. Already in the beginning of the 90s HTTP caches have been proposed, which were deployed in the domains of the network operators. These traditional HTTP caches rely on URLs to identify resources and to avoid transferring the same data twice. Unfortunately today a specific content might be available under different URLs. Furthermore many HTTP connections are personalized and therefore caching is often disabled by content producers. So traditional HTTP caching became inefficient for the network operators. In this paper we propose a method to improve the efficiency of HTTP caching. Our approach is based mainly on hash keys as additional identifiers in the header of HTTP messages. By that identification of the transferred content is more precise than with URLs. Beside this we show how caching can be achieved even in the presence of personalization in HTTP messages and how content producers remain full control over their content although it is cached by ISPs.

The work discusses nonmonotonicity in terms of trust management systems and presents model allowing for credential revocation in the Role-based Trust-management Framework. A freshness constraints have been adopted into RT Framework in order to overcome nonmonotonicity and turn it to be temporarily monotonic. The proposed model allows for freshness requirements specification on policy level and utilises freshness graph in order to perform propagation of freshness requirements along credential chains. Finally, an evaluation of the model against real-life scenario has been performed.

In wireless network design and positioning it is essential to use radio propagation models for the applied frequency and environment. There are many propagation models available for both indoor and outdoor environments; however, they are not applicable for 433 MHz ISM frequency, which is perfectly suitable for smart metering and sensor networking applications.

During our work, we gathered the most common propagation models available in scientific literature, broke them down to components and analyzed their behavior. Based on our research and measurements, a method was developed to create a propagation model for both indoor and outdoor environment optimized for 433 MHz frequency.

The possible application areas of the proposed models: smart metering, sensor networks, positioning.

Today, the research field of assisted living technologies is becoming more and more important. In this paper, an intelligent space framework is going to be presented which can be applied as a framework for assisted living. There are two beneficial properties which can improve the performance of the presented framework. The first is the use of semantic information which increases the flexibility and the autonomy of the framework so that it maximizes the collaboration possibilities between the entities of the intelligent space. The second is the relation to cognitive info-communications which makes it possible to use not only conventional channels in user interaction, but other alternative channels as well, i.e. to represent the user as a complex source and drain of several kinds of information. In this paper, it is described how these properties of the framework can be adopted in this special application field.

The deterministic network coding has several advantages over random network coding methods, like lower communication overhead and faster linear independence check. We would like to create a P2P content sharing simulation environment, where nodes communicate with deterministic network coding to observe the different properties of deterministic source coding. Our simulator is based on the Peersim generic P2P simulation framework. We examine the diversity of block combinations, as this property is the key for increasing the P2P network reliability.

Tablet PCs, iPads and mobile phones all include facilities to browse the mobile Internet. The costs of mobile Internet access may become extraordinary, however, when the data limit is exceeded or when the user is roaming abroad without a roaming data plan. Since users may see advertisements as unwanted traffic, they can be confronted with a bill of which a significant part is caused by data they did not ask for. The goal of this paper is to investigate the amount of data generated by advertisements when browsing, and the potential costs of such advertisements for average users. Our analysis shows that web advertisements take up 7-9% of the total data traffic, depending on Flash usage.