Linear analysis of a terahertz staggered double-grating arrays waveguide Cerenkov traveling wave amplifier

Based on a sheet electron beam propagating through the tunnel of a staggered double-grating arrays waveguide (SDGAW) slow-wave structure (SWS), a three dimensional linear theory for describing beam-wave interaction is presented, in which the higher order terms inside the groove were retained.

With the optimized parameters, a 1THz SDGAW Cerenkov traveling wave amplifier (CTWA) may obtain a moderate net gain larger than 10dB/cm in 0.92THz to 1.145THz considering the serious Ohmic losses in THz frequency range.

Poster: A simulator for heterogeneous vehicular networks

We are aiming to better investigate heterogeneous vehicular networking technologies to overcome the shortcomings of using just a single wireless technology. Performance evaluation is usually done using simulation, for which we need integrated tools supporting WiFi, IEEE 802.11p, cellular technology, and mobility feedback.

The established vehicular networking simulators such as Veins, iTETRIS, or VSimRTI, however, currently have no support for such heterogeneous networking, in particular for Long Term Evolution (LTE). We present a new integrated simulation framework based on the popular and mature Veins framework named VeinsLTE. We present early results that clearly demonstrate the potential of this integrated approach.

Recent open source wireless sensor network supporting simulators: A performance comparison

Any common methodology for functionality research in the field of communication systems engineering is network simulation. There is always the overriding worry when utilizing simulation that the results may not reflect appropriate behavior. Therefore, it is important to recognize the particular strengths and also flaws of such simulators. There are a variety of network simulators, as an illustration, NS-2, NS-3, OMNET++, SWAN, OPNET, Jist, and also GloMoSiM and so forth.

As a result, the selection of any network simulator for assessing investigation function is really a critical activity for researchers. The leading emphasis in this research is usually to examine the particular advanced, open source network simulators based on the parameters, CPU usage, memory usage, computational time period, and also scalibility by simulating a wireless sensor network routing protocol, to identify a best network simulator to the investigation area.

Building and evaluating P2P systems using the Kompics component framework

We present a framework for building and evaluating P2P systems in simulation, local execution, and distributed deployment. Such uniform system evaluations increase confidence in the obtained results. We briefly introduce the Kompics component model and its P2P framework. We describe the component architecture of a Kompics P2P system and show how to define experiment scenarios for large dynamic systems. The same experiments are conducted in reproducible simulation, in real-time execution on a single machine, and distributed over a local cluster or a wide area network.

This demonstration shows the component oriented design and the evaluation of two P2P systems implemented in Kompics: Chord and Cyclon. We simulate the systems and then we execute them in realtime. During realtime execution we monitor the dynamic behavior of the systems and interact with them through their Web-based interfaces. We demonstrate how component-oriented design enables seamless switching between alternative protocols.

Programmable firewall using Software Defined Networking

Software Defined Networking is an exciting technology that enables innovation and flexibility in designing and managing networks, but it also introduces new security issues. Our Major challenge is to build powerful and flexible firewall applications for protecting software defined based networks. In this paper we focus on designing and developing OpenFlow based firewall application.

The implementation shows that most of the firewall functionalities can be built using software, without need of dedicated hardware. We are using open source POX Controller based on python for our experiments. To perform experiment, we have used VMPlayer virtualization solution and installed Mininet emulator for creating network topologies. In this paper, we present the implementation details as well as experimentation results of firewall application.

Independent transient plane design for protection in OpenFlow-based networks

Network protection against link failure is required to allow packets to reach the destination with minimal packet loss when a failure occurs. When a link fails, traffic that attempts to use the failed link is interrupted. Typically, routers in the network discover the failure and find a new route to bypass the failed link. Alternatively, well-known segment protection schemes can also be used to speed up the link recovery time by rerouting packets locally through precalculated protection paths. However, several backup paths have to be prepared for each primary path, making path configuration rather complex and poorly scalable.

This paper proposes a design for fast rerouting in an OpenFlow-based network. This new design reduces the number of flow entries and the number of configuration messages needed for network rerouting, which in turn reduces the memory size needed in each switch and the CPU load at the controller. We show empirically and using simulations that our design can reduce the number of flow entries and configuration messages needed by about 60% and 75%, respectively, when compared with an existing OpenFlow-based segment protection design. Furthermore, we implement the proposed design on a pan-European network and show that our design can recover from a link failure in as little as 25 ms.

Round-robin based load balancing in Software Defined Networking

These days our networks have to handle large amount of traffic, serve thousands of clients. It is very difficult for a single server to handle such huge load. The solution is to use multiple servers with load balancer acting as a front end. The clients will send the requests to the load balancer. The load balancer will forward the client requests to different servers depending upon load balancing strategy. Load balancer use dedicated hardware. That hardware is expensive and inflexible. Currently available load balancers contain few algorithms that can be used.

Network administrators can not create their own algorithms since traditional load balancer are vendor locked, non programmable. On the other hand SDN load balancers are programmable and allow you to design and implement your own load balancing strategy. Other advantages of SDN load balancer is we do not need dedicated hardware. The dumb silicon device can be converted to a powerful load balancer by using SDN controllers. In this paper we are implementing and comparing Round-Robin load balancing strategy with already implemented random strategy using an OpenFlow switch connected to a POX controller.

Simulation based comparative study of MAODV, ODMRP and Gossip protocol

Multicasting is intended for group communication, which supports the dissemination of information from a sender to all the receivers in a group. Mobile wireless Ad Hoc networks are infrastructure less and often used to operate under unattended mode, posing problems like scarcity of bandwidth, short lifetime of the nodes due to power constraints, and dynamic topology caused by the mobility of nodes. Multiple multicasting protocols have been proposed for Ad Hoc networks based on different approaches and some performance simulations are made on numbers of routing protocols.

In this paper, we are comparing three different protocols ODMRP (On-Demand Multicast Routing Protocol), MAODV (Multicast Ad Hoc On-Demand Distance Vector), and Anonymous Gossip (AG) using packet delivery fraction as performance parameter while varying various network parameters such as number of nodes, transmission range and mobility of nodes using the tool GloMoSim. We have also taken average end to end delay as performance metric for analyzing the best protocol for delay sensitive applications. To the best of our knowledge, comparison of these protocols have not yet being done on the parameter chosen by us in the literature. We look at the relative strengths, weaknesses, and applicability of each multicast protocol to diverse situations.

A routing Ad Hoc network for disaster scenarios

In this work we study the wireless networks without infrastructure especially in emergency situations where groups of rescuers must be on site to accomplish emergency tasks, which is necessary to establish a wireless communication in real time between individuals or groups. The nature of MANET (Mobile Ad Hoc network) makes it suitable to be used in the context of emergencies and that, when the existing infrastructure is down or severely overloaded. In emergency cases Ad Hoc networks can be used to deploy quickly small spontaneous networks. Since nodes are mobile, the network topology may change rapidly and randomly.

The increasing mobility of terminals makes them progressively dependent on their autonomy from the power source; this is illustrated by introducing many mobility models and using many scenario of mobility in emergency situation. Energy efficiency in emergency scenario is the main objective of this paper, achieved by the combination of a low-power mode algorithm and a power-aware routing strategy. A selected set of simulation studies indicate a reduction in energy consumption and a significant increase in node lifetime whereas network performance is not affected significantly. This is the big interest of our works in emergency situation, by increasing life time of nodes individuals can communicate longer and give more chance to rescuers to find them.

Dempster-Shafer evidence theory based trust management strategy against cooperative black hole attacks and gray hole attacks in MANETs

The MANETs have been experiencing exponential growth in the past decade. However, their vulnerability to various attacks makes the security problem extremely prominent. The main reasons are its distributed, self-organized and infrastructure independent natures. As concerning these problems, trust management scheme is a common way to detect and isolate the compromised nodes when a cryptography mechanism shows a failure facing inner attacks. Among huge numbers of attacks, black hole attack may collapse the network by depriving the route of the normal communication. The conventional proposed method achieved good performance facing black hole attack, while failing to detect gray hole attacks.

In this paper, a Dempster-Shafer (D-S) evidence based trust management strategy is proposed to conquer not only cooperative black hole attack but also gray hole attack. In the proposed method, a neighbour observing model based on watchdog mechanism is used to detect single black hole attack by focusing on the direct trust value (DTV). Historical evidence is also taken into consideration to go against gray hole attacks. Then, a neighbour recommendation model companied with indirect trust value (ITV) is used to figure out the cooperative black hole attack. D-S evidence theory is implemented to combine ITVs from different neighbours. Some of the neighbour nodes may declare a false ITV, which effect can also be diminished through the proposed method. The simulation is firstly conducted in the Matlab to evaluate the performance of the algorithm. Then the security routing protocol is implemented in the GloMoSim to evaluate the effectiveness of the strategy. Both of them show good results and demonstrate the advantages of proposed method by punishing malicious actions to prevent the camouflage and deception in the attacks.