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.

Analysis of effect of mobility and transmission power on AODV and DSR in mobile Adhoc network

Now a days there is a remarkable growth in telecommunication technology which makes users of mobile electronic devices accessible to a communication network. These electronic devices are nothing but the nodes of the Mobile Ad hoc Network (MANET). Each node can move from one place to other during communication and this mobility is having its effect on performance of the network. Mobility changes when speed of the node and pause time with which it moves changes. Change in mobility causes break of link with neighboring nodes as a result of which the performance of a network may be reduced.

A number of packets are dropped at different layers of the network. This paper describes the analysis of change in performance due to change in mobility and transmission power. The parameters describing the reason of variation in performance are (1) number of link breaks and (2) number of packet delivered. (3)End to end delay. The simulator we have used in our work for the calculation of performance matrices is GLOMOSIM. The performance comparison has also made between two types of on demand routing protocols AODV and DSR.

A collaborative reputation approach to avoid misbehaving nodes in MANETs

Ad-hoc networks carry out routing and forwarding functions through available nodes. These nodes act as base stations and also are involved in route discovery and maintenance, forwarding traffic, and network management functions. Nodes expend most of their energy to forward packets to others without receiving any direct gain from doing so. A misbehaving and greedy node only considers its own short-term utility, and it may not choose to participate within the network.

A reputation approach (RAP) is proposed in this paper, based on the reputation model that is used to detect and isolate misbehaving nodes which do not cooperate in forwarding packets of other nodes. Promising results are found through extensive simulation using GloMoSim in identifying selfish nodes.

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.

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.

Low power and high performance MOSFET

To analysis leakage current and delay for Double Gate MOSFET with Single gate MOSFET at 45nm in CMOS Technology by using the Cadence Virtuoso simulation tool. When compared to single gate MOSFET, the leakage current and delay are observed to be reduced in double gate MOSFET. The drive current remains the same for both single and double gate MOSFET based on Vgs but the short channel characteristics of double gate MOSFET gets improved.

Double gate MOSFET is mostly recommended for low power and high performance application. When compared to bulk Si single gate device, the total power utilization of inverter, static, dynamic circuit and latch by using double gate demonstrates that leakage current and delay reduced by a factor of over 10X.

System analysis for optimizing various parameters to mitigate the effects of satellite vibration on inter-satellite optical wireless communication

Inter-satellite links are necessary between satellites in orbits around the earth for data transmission between satellites and also for efficient data relay from one satellite to other and then to ground stations. Inter-satellite Optical Wireless Communication deals with the use of wireless optical communication using lasers instead of conventional radio and microwave systems. Optical communication using lasers provide many advantages over conventional radio frequency systems.

A major problem existing in this wireless optical communication for inter-satellite links is the effects of satellite vibration, which results in serious pointing errors that degrade the performance. Performance of this system also depends on various parameters like transmitted power, data rate and antenna aperture which are analyzed using OptiSystem simulation software. This paper suggests ways to tackle effects of satellite vibration by optimizing the parameters of system design. The results of this study could be used further to design a feedback loop to correct effects of satellite vibrations in the system.

Revisiting TCP Outcast Problem Using DCTCP in Data Center Networks

Data Center Networks (DCNs) today are used to compute and store the data of multiple users because of low cost, flexibility and availability. In this multi-tenant cloud environment, resources are shared among different users. Suppose two users fetch data at same time from the same DCNs, one fetches small amount of data (like web search) while another user fetches larger amount of data (like software update). If these large set of flows and small set of flows arrive at two different input ports of a switch and compete for same output port, then large flow packets get the buffer while small flow packets are dropped consecutively.

This issue occurs due to drop tail implementation of queue in switches and as one set of flows is outcast by other, the problem is known as TCP Outcast. While a few studies have already explored the TCP Outcast problem, this paper aims to revisit this problem by using DCTCP in DCNs. The experiments carried out using Mininet show that DCTCP solves the problem of TCP Outcast by ensuring fairness for all types of flows.

Secure communication system for wearable devices wireless intra body communication

This paper explains how intra-body communication can be used to establish a secure communicationchannel for wearable devices. Intra-body communication transfers data using the human body as its conductor. This paper describes a secure communication system that supports multiple wearable slave devices.

Our prototype, wearable on the wrist, has an integrated processor to control the intra-bodycommunication module. Instead of using radio transmission, the module uses the human body, thus maximizing the security of transmitted signals.