Charalabos Skianis

Energy efficient network coding-based MAC for cooperative ARQ wireless networks

In this paper we introduce a network coding-aided energy efficient Medium Access Control (MAC) protocol that coordinates the transmissions among a set of relay nodes which act as helpers in cooperative Automatic Repeat reQuest-based (ARQ-based) wireless networks. Applying network coding techniques, we achieve to increase the energy efficiency of the network without compromising the system performance in terms of Quality of Service. Our proposed solution is evaluated by both analytical and simulation results.

Optimized fusion of heterogeneous wireless networks based on media-independent handover operations [Accepted from Open Call]

In recent years a plethora of wireless technologies has become available. Users may efficiently utilize heterogeneous network infrastructures while moving among different access networks in order to attain better services, everywhere and at any time, following the always best connected concept. In this article enhanced handover functionality is described for integrated Wi-Fi/WiMAX networks, based on the recently established IEEE 802.21 standard that serves to glue together heterogeneous wireless access technologies. Moreover, alternative implementation choices are introduced with an emphasis on the mapping of primitives between the IEEE 802.21 standard and the various underlying access network technologies. As a result, optimized media-independent handover operations are provided alongside highlighted possible improvements to the related standards.

A Survey on Buffer-Aided Relay Selection

Relays receive and retransmit signals between one or more sources and one or more destinations. Cooperative relaying is a novel technique for wireless communications that increases throughput and extends the coverage of networks. The task of relay selection serves as a building block to realize cooperative relaying. Recently, relays with buffers have been incorporated into cooperative relaying providing extra degrees of freedom in selection, thus improving various performance metrics, such as outage probability, power reduction, and throughput, at the expense of tolerating an increase in packet delay. In this survey, we review and classify various buffer-aided relay selection policies and discuss their importance through applications. The classification is mainly based on the following aspects: 1) duplexing capabilities, 2) channel state information (CSI), 3) transmission strategies, 4) relay mode, and 5) performance metrics. Relay selection policies for enhanced physical-layer security and cognitive communications with reduced interference are also discussed. Then, a framework for modeling such algorithms is presented based on Markov Chain theory. In addition, performance evaluation is conducted for various buffer-aided relay selection algorithms. To provide a broad perspective on the role of buffer-aided relay selection, various issues relevant to fifth-generation (5G) networks are discussed. Finally, we draw conclusion and discuss current challenges, possible future directions, and emerging technologies.

Service-driven inter-domain QoS monitoring system for large-scale IP and DVB networks

There is a growing synergy between well-established Service Providers (SP), Content Providers (CP), and Network Providers (NP), to propose new value-added services, and hence opening new markets to generate further revenues. Meanwhile, the explosive increasing amount of multimedia content to be offered in the Internet and the heterogeneity of the underlying networking technologies demand the provision of new QoS-enabled mechanisms and architecture to efficiently control, manage and monitor the networks. Quality of service monitoring is becoming crucial to SPs for providing quantified QoS-based services and service assurance and to NPs for managing network resources. This paper proposes a framework for large scale inter-domain QoS monitoring in heterogeneous networks including IP and DVB networks that has been developed in the IST-ENTHRONE project of European Commission. One of the main aims is actually to allow high cooperation between different providers while keeping intact the authority, confidentiality, and full control of each provider over its underlying resources. The proposed monitoring framework consists of a layered architecture with two signaling protocols namely an inter-domain monitoring signaling protocol (EQoS-RM), and an intra-domain active measurement signaling protocol (Emon). The proposed QoS monitoring system is service-driven in the sense that it aimed at providing in service verification of QoS performance guarantees for the services offered to the users by the providers. To achieve this, it uses both QoS probes that perform both active and passive monitoring at different levels of abstraction employing node and network wide measurements and application-level perceived quality meters for detecting quality degradation. As such, this framework specifies three types of QoS monitoring components operating at different levels: at network element or node, at network and at service levels. This proposed system also provides monitoring information to NPs in order to assist in managing the operational status of their networks. Design and implementation of the proposed QoS monitoring system is described in this paper. Some experimental assessments of this service-driven QoS monitoring system prove its functioning in terms of accuracy and responsiveness in providing the necessary results.

QoS provisioning and policy management in a broker-based CR network architecture

The paper presents an infrastructure-based cognitive radio network architecture that enables for TV white spaces exploitation, QoS provisioning and policy management, under the real time secondary spectrum market policy. It describes the configuration of a spectrum broker that coordinates the radio resource management process (RRM) among LTE secondary systems as a matter of maximum possible TVWS utilisation and minimum frequency fragmentation, and also administrates the economics of such transactions towards maximum revenue following a fixed-price trading. The validity of the proposed architecture is verified via a number of tests carried under controlled experimental conditions (i.e. simulations) exploiting a decision-making algorithm.

Trust establishment in ad hoc and sensor networks

Ad hoc and sensor networks highly depend on the distributed cooperation among network nodes. Trust establishment frameworks provide the means for representing, evaluating, maintaining and distributing trust within the network, and serve as the basis for higher level security services. This paper provides a state-of-the-art review of trust establishment frameworks for ad hoc and sensor networks. Certain types of frameworks are identified, such as behavior-based and certificate-based, according to their scope, purpose and admissible types of evidence. Moreover, hierarchical and distributed frameworks are discussed, based on the type of ad hoc and sensor networks they are designed for. The review is complemented by a comparative study built both on criteria specific to each category and on common criteria, grouped into three distinct classes: supported trust characteristics, complexity and requirements, and deployment complexity and flexibility.

Case study of a dimmable outdoor lighting system with intelligent management and remote control

The following paper introduces the experimental development of an energy-efficient, intelligent outdoor lighting management and monitoring system with remote control. The data communication system is based on wireless personal area networks that support IP technology for connecting all nodes and network entities with a sink node which is the gateway to the remote management and monitoring service. The proposed system maintains lighting at a low level until vehicle or pedestrian motion is detected by a set of proximity sensors. In this case, the level of lighting is increased in order to provide better visibility while the area is occupied and dims to a lower level when the area is clear again. At the same time, data regarding lamp parameters like status and operation dimming level are transferred to the management system via a bidirectional channel that may receive feedback based on a certain system operation profile. The system can be easily installed over street lighting systems that use old and inefficient technologies without major cost thus, lowering energy consumption. The technologies used can make it part of a larger IP network following the concept of “internet of things” which may support smart road applications. Some aspects of the wireless communication system and experimental measurements are presented and discussed.

Performance evaluation of single and multi-channel actor to actor communication for wireless sensor actor networks

Abstract The paper discusses two distributed actor to actor communication schemes (a single channel one and a multi-channel one) for wireless sensor actor networks (WSANs). The performance of these two schemes is evaluated through analysis and simulation. The simulation results show that the whole analysis is fairly accurate. It is further proven that the multi-channel scheme has better performance than the single channel one. The key feature of the multi-channel scheme is the separation of the single hop from the multi-hop traffic.

Trust establishment in sensor networks: behaviour-based, certificate-based and a combinational approach

Sensor networks highly depend on the distributed cooperation among network nodes. Trust establishment frameworks provide the means for representing, evaluating, maintaining and distributing trust within the network, and serve as the basis for higher level security services. This paper provides a state-of-the art review of trust establishment frameworks for ad hoc and sensor networks. Certain types of frameworks are identified, such as behaviour-based and certificate-based, according to their scope, purpose and admissible types of evidence. The review is complemented by a comparative study built both on criteria specific to each category and on common criteria, grouped into three distinct classes: supported trust characteristics, complexity and requirements and deployment complexity and flexibility. We then present a trust establishment framework targeted for sensor networks that combines aspects from the two alternative approaches on trust establishment on common evaluation metrics, so that it can uniformly support the needs of nodes with highly diverse network roles and capabilities.

Interactions between intelligent multimodal terminals and a network management system in a B3G context

This work addresses aspects relevant to the optimal joint exploitation of heterogeneous wireless networks in an ‘all-IP’ integrated infrastructure, frequently called ‘Beyond 3G Systems’ (B3G) or composite radio networks. After briefly reviewing general architectural aspects pertaining to such systems, the paper focuses to the management functionality possessed by B3G systems and highlights the benefits that stem from sharing intelligence among the hybrid network (through a network management system) and the multimodal wireless terminals. In particular, the paper discusses an appropriate signaling protocol for the exchange of information between management modules at the network and the wireless terminal, investigates associated performance aspects and correlates the relevant findings with measurement results obtained from experiments over a prototype B3G network testbed. Copyright