Abstract: A wireless sensor network consists from a collection of transceivers positioned in the plane. Each transceiver is equipped with a limited battery charge. The battery charge is reduced after each transmission, depending on the transmission distance. One of the major problems in wireless ad hoc network is designing a route network traffic algorithm that will maximize the lifetime of the network i.e., the number of successful transmissions. Our objective is to construct a broadcast routing tree rooted at the source node with the longest possible lifetime. We perform a simulative study of the problem and show an improvement to currently existing BIP algorithm [18].
Abstract: Heterogeneous networks allow mobile terminals to take advantage of complementary radio technologies for their concurrent connections. In this paper we propose a mechanism for automated radio access network selection with several novelties: It enables terminals to build prioritized lists of target access networks independently for each of their active connections. It aims to satisfy user preferences. Lastly, it operates with two decision-making points (mobile terminal and core network), splitting the complexity of the overall process. After
discussing the functionality of the proposed mechanism, we present its formal specification in SDL. Finally, a test-bed implementation comprising two access networks is presented. It uses open source tools and it is based on Mobile IP, showing the feasibility of our proposal.
Abstract: The rapid evolution of the telecommunication domain increases the performance of different access networks continuously. New services, especially in the domain multimedia content distribution, require higher and higher bandwidth at the user’s and service provider’s side [1].
Multimedia services like Video on Demand, IPTV and live streaming were introduced in the past and are still improved in quality and quantity. Multimedia streams and Peer to Peer (P2P) file sharing dominates the worldwide Internet traffic nowadays and will continue further.
The user acceptance of enjoying multimedia content over the Internet will grow steadily together with the increasing quality of the available multimedia content. Network operators and service providers have to face the growths, by either increasing their service platform with higher performance and bandwidth or introducing a scalable solution.
We present the design and implementation of a scalable Peer-to-Peer live streaming overlay architecture for Next-Generation-Networks (NGN) in this paper that addresses this challenge.
Abstract: In the wireless sensor networks composed of battery-powered sensor nodes, one of the main issues is how to save power consumption at each node. The usual approach to this problem is to activate only necessary nodes (e.g., those nodes which compose a backbone network), and to put other nodes to sleep. One such algorithm using location information is GAF (Geographical Adaptive Fidelity). GAF is enhanced to HGAF (Hierarchical Geographical Adaptive Fidelity). In this paper, we study the energy-efficient partition of a 3 dimensional sensor field into cells. Further, we give a theoretical upper bound on the cell size for this problem.
Abstract: Functioning and effective telecommunications are fundamental during and after disasters, be they natural or man-made, and it is specially in these particular situations that communications might congest at a very high rate. Therefore, emergency sessions need to be prioritized over non-emergency sessions to ensure the best coordination. For the more, it becomes clear that the control of Quality of Service in the on-going non-emergency sessions or even the acceptance of new non-emergency sessions is a key feature for the success of emergency services in critical situations. For all these reasons we propose a novel portable model for telecommunications operators for the support of emergency services, which through specific thresholds and dynamic policies will enhance the performance of Next Generation Networks under exceptional circumstances. The model complements the work done in emergency situations from other related work and conveys with the requirements defined by the ITU-T.
Abstract: Recent technological advances in sensors, low-power microelectronics and miniaturization, and wireless networking enabled the design and proliferation of wireless sensor networks capable of autonomously monitoring and controlling environments. One of the most promising applications of sensor networks is for human health monitoring. A number of tiny wireless sensors, strategically placed on the human body, create a wireless body area network (WBAN) that can monitor various vital signs, providing real-time feedback to the user and medical personnel. The wireless body area networks promise to revolutionize health monitoring. Since the sensors collect personal medical data, security and privacy are important components in this kind of networks (WBAN). It is a challenge to implement traditional security infrastructures in these types of lightweight networks, since they are by design limited in both computational and communication resources. In this paper, we present an approach which exploits physiological signals (electrocardiogram (ECG)) to address security issues in WBAN (a Biometric Approach for Secure Communications in Wireless Body Area Network). Our approach manages the generation and distribution of symmetric cryptographic keys to constituent sensors in a WBAN and protects the privacy. The analysis results, demonstrates the feasibility and efficiency of the approach for delivering secure communications in WBAN.
Abstract: In the recent years, several transport protocols have been proposed for very high bandwidth-delay product networks. However, little is known about the performance of these new mechanisms as well as the interaction with other elements of the network (such as the RED queue management). On the other hand, the control-theoretic approach has proved to be a very useful tool in order to get analytical insight into the performance of congestion control algorithms. In this paper, a control-theoretic research framework is designed and implemented for analyzing high speed transport protocol proposals in network environments with RED active queue management. As a case study, a comprehensive control-theoretic analysis of a promising proposal, namely the HighSpeed TCP is provided. The main contributions of this paper are the following. First, we provide a fluid-flow model for HighSpeed TCP/RED networks. Second, a comprehensive and systematic implementation methodology is described in detail, and a Simulink-based framework is designed for analyzing fluid-based models. Third, we derive a stability condition for HighSpeed TCP/RED networks. The flow-level results are validated by packet-level simulations conducted in Ns-2. Finally, an extension of the framework is presented that makes it capable of describing the interaction of different transport protocols.
Abstract: In dynamic networks with flexible memberships, group signatures and distributed signatures are an important problem. Dynamic threshold cryptosystems are best suited to realize distributed signatures in dynamic (e.g. ad-hoc) networks. Without a group manager or a trusted third party even more flexible scenarios can be realized.
Gennaro et al. [1] showed, it is possible to dynamically increase the size of the signer group, without altering the public key. We extend this idea by removing members from the group, also without changing the public key. This is an important feature for dynamic groups, since it is very common, e.g. in ad-hoc networks that members leave a group.
Gennaro et al. used RSA and bi-variate polynomials for their scheme. In contrast, we developed a DL-based scheme that uses ideas from the field of proactive secret sharing (PSS). One advantage of our scheme is the possibility to use elliptic curve cryptography and thereby decrease the communication and computation complexity through a smaller security parameter.
Our proposal is an efficient threshold cryptosystem that is able to adapt the group size in both directions. Since it is not possible to realize a non-interactive scheme with the ability to remove members (while the public key stays unchanged), we realized an interactive scheme whose communication efficiency is highly optimized to compete with non-interactive schemes. Our contribution holds against passive and active information theoretic adversaries.
Abstract: Large-scale wireless LAN systems based on the IEEE 802.11 standards have become the most successful wireless networks deployed in large organizations, such as educational campuses and corporate warehouses. However, the suite of IEEE 802.11 MAC protocols, including DCF, PCF and EDCA mechanisms, was unable to meet the challenges to provide collision freedom and differentiated quality of services. We propose a channel access scheduling protocol based on Latin squares, called DCLASS (Distributed Coordination based on LAtin SquareS), that provisions a set of highly desirable features to large scale wireless networks with stringent performance demands. DCLASS is scalable, fair, and co-exists with IEEE 802.11 nodes with traditional DCF mechanisms. The performance of DCLASS is evaluated using an IEEE standards compliant simulation toolkit, QualNet 4.5, in distributed WLAN systems. The experiment results show the near-optimum performance of DCLASS in contrast to IEEE 802.11 DCF under various scenarios.
Abstract: In this paper, we propose a new EIFS strategy to improve the performance in IEEE 802.11. In IEEE 802.11 specifications, the EIFS time delay is activated after a node initiates an
unsuccessful transmission. The new EIFS strategy uses the same activation mechanism as the specifications. The major difference between the standard EIFS and the new EIFS strategy is when to deactivate such time delay. According to the specification, a node deactivates the EIFS time delay whenever any node in system executes a successful transmission. However, in our proposed EIFS strategy, a node deactivates the EIFS time delay only when it has completed a successful transmission. Performance results via simulations have shown that this new strategy is able to boost the system performance significantly.
Abstract: The wireless personal area network (WPAN) is an emerging wireless technology for future short range indoor and outdoor communication applications. The IEEE 802.15.3 medium access control (MAC) is proposed, especially, for short range high data rates applications in WPAN, to coordinate the access to the wireless medium among the competing devices. A thought of an improved backoff algorithm (IBA) was brought up in [3]. In this paper, we propose an IBA for contention process of IEEE 802.15.3, where binary exponential backoff (BEB) is originally used. Here, we compare both BEB and IBA algorithms, and show the superiority of IBA over BEB in terms of channel efficiency, channel access delay and energy efficiency.
Abstract: HSDPA defines a new High Speed Shared Channel (HS-DSCH) which allows for practical speeds up to 10 Mbps. Among all the changes introduced by HSDPA, the most prominent ones regarding QoS are the inclusion of “link adaptation”, “Hybrid ARQ” and the quick “Scheduling” algorithms. In HSDPA the Radio Network Controller (RNC) is still the responsible for admitting new users but also for handling different kinds of traffics of
different users over the same channel. One of the mostly adopted solutions for admitting new users assuring QoS comprises an admission control algorithm based on performance, with the cells power as the limiting resource. This kind of algorithms makes use of a static “guard power offset” for users whose channel conditions worsen in the course of the connection. In this paper, we propose two admission control algorithms that take into account that this guard power varies according to the channel conditions of each user, the number of allowed users, the service and the transmission speed that they require, and the power used by the cell on each Transmission Time Interval (TTI).
The coverage radius of the cell will be divided into three concentric rings, and those users with better channel conditions (the ones nearer to the Node-B) will be assigned with higher priority. Since they will need less power than those farther they will have a better chance on satisfying their needs. Simulation scenario in Matlab shows the behavior of these proposals by comparing how many users are admitted and how many of them are satisfied.
Abstract: Converged telecommunication networks, which simultaneously support a growing variety of services through a common network infrastructure, are aimed at significantly reducing network expenditures. This trend has encouraged the development of a unified network paradigm capable of supporting a wide variety of cost-effective recovery solutions, each of which may cope differently with fiber cuts and nodal equipment failures in order to satisfy service-dependent requirements. Expansion of the Origin-Destination (OD) Cycles approach
is used to meet that challenge by offering ten different policies for survivability and their relative performance measures in terms of consumption of network resources and the resulting times of recovery. For practical purposes the scope of failure scenarios is limited to single and double-network failures only, even though the approach suggested is generic and can basically address even more complex events. Three test networks are extensively analyzed to demonstrate the paradigm developed and to present some useful observations
about the relative positioning of the policies considered for survivability.
Abstract: The routing engine is the essential part of a router. As a software component, the routing engine is used to control the router activities and to build the data forwarding table. Along with the hardware evolution, several software generations for routing engines have been experienced. In this paper, we first review the different routing engine architectures over the time and their main components. In some previous papers, we have investigated new directions for routing engine development for next generation routers, where specific distributed architectures have been proposed for several routing protocols. Taking into account the increasing traffic in the core networks, we next propose a framework integrating all specific distributed routing protocol architectures in order to significantly improve the scalability of the next generation routers. Bottlenecks are reduced, resulting in improving both the overall performance and the resiliency in the presence of faults. The scalability of the proposed distributed framework is estimated with respect to each routing protocol.
Abstract: Since the appearance of the data networks, many researchers have focused their efforts designing and developing many ways to communicate the network devices. This paper will introduce the reader to the network protocols and algorithms that are used for data transfer between devices. The meanings of the terms, their description and their explanation are provided. Finally, the scope of the journal and its aim are presented.
