Revathi Venkataraman

Regression-based trust model for mobile ad hoc networks

The focus of this study is to propose a generalised trust-model over routing protocols in mobile ad hoc networks (MANETs). It is observed that the presence of malicious nodes is a critical factor affecting the network performance in an ad hoc network. The novelty in the approach is that the notion of trust can be easily incorporated into any routing protocol in MANETs. The vector auto regression based trust model is introduced to identify malicious nodes that launch multiple attacks in the network. The proposed trust model is incorporated over ad hoc on-demand distance vector (AODV) routing protocol and optimised link state routing (OLSR) protocol in MANETs. The performance evaluations show that by carefully setting the trust parameters, substantial benefit in terms of throughput can be obtained with minimal overheads. The computed trust and confidence values are introduced into the path computation process of the ad hoc routing protocols. It was observed that the nodes in the network were able to learn the malicious activities of their neighbours and hence, alternate trustworthy paths are taken to avoid data loss in the network, with trade-offs in end-to-end packet delay and routing traffic.

Prevention of flooding attacks in mobile ad hoc networks

The lack of any centralized infrastructure in mobile ad hoc networks (MANET) is one of the greatest security concerns in the deployment of wireless networks. Thus communication in MANET functions properly only if the participating nodes cooperate in routing without any malicious intention. However, some of the nodes may be malicious in their behavior, by indulging in flooding attacks on their neighbors. Some others may act malicious by launching active security attacks like denial of service. This paper addresses few related works done on trust evaluation and establishment in ad hoc networks. Related works on flooding attack prevention are reviewed. A new trust approach based on the extent of friendship between the nodes is proposed which makes the nodes to co-operate and prevent flooding attacks in an ad hoc environment. The performance of the trust algorithm is tested in an ad hoc network implementing the Dynamic Source Routing (DSR) protocol.

Trust-based backpressure routing in wireless sensor networks

In this paper, we apply a vector autoregression VAR based trust model over the backpressure collection protocol BCP, a collection mechanism based on dynamic backpressure routing in wireless sensor networks WSNs. The backpressure scheduling is known for being throughput optimal. In the presence of malicious nodes, the throughput optimality no longer holds. This affects the network performance in collection tree applications of sensor networks. We apply an autoregression based scheme to embed trust into the link weights, so that the trusted links are scheduled. We have evaluated our work in a real sensor network testbed and shown that by carefully setting the trust parameters, substantial benefit in terms of throughput can be obtained with minimal overheads. Our results show that even when 50% of network nodes are malicious, VAR trust offers approximately 73% throughput and ensures reliable routing, with a small trade-off in the end-to-end packet delay and energy consumptions.

Fault tolerant and dynamic file sharing ability in mobile ad hoc networks

This paper proposes a new method for replication of files within a mobile adhoc network based on the prediction of the drift of the mobile nodes. The main feature of mobile ad hoc network is the dynamic topology. That is the nodes in the network are in mobile. To facilitate file sharing in mobile networks the only technique is file replication. Shared files are available at all times even if the owner of the file drifts away. The goal is to ensure that files autonomously maintain replica levels over time in a potentially dynamic and hostile environment. Also the proposed algorithm ensures that only those files are to be replicated which are about to exit from the network ensuring better efficiency and fewer overheads. Existing algorithms are simulated in Netlogo simulation environment and observations are compared with the proposed technique to check the efficiency of all algorithms.

Implementation of a trust model over AODV in a wireless ad hoc testbed

We have customized Ad hoc On demand Distance Vector (AODV) protocol and augmented security aspect in real time scenario using numeric step values called Trust assigned to finite number of neighbor nodes to evaluate network behavior, subsequently secure the network by barricading the network from malicious nodes in Blackhole and flooding attack modes. Experiments were carried out using a custom-made testbed built on wxPython that supports various characteristics of nodes like variable data rates, node positions and malicious behavior for testing and display results in a graphical format. The results have favored aforementioned proposal showing a 70% increase in throughput obtained from trust implemented experimentation as compared to standard one without the trust parameter. The overhead in trusted scenario encountered was minimal despite the end to end delay of packets being higher than the traditional AODV by 30 msec. Hence, we have concluded that our method of using trust has resulted in a secured reactive protocol with applications suited for wireless attack prone environment when applied to a network consisting of four nodes. Our work is also the first ever implementation of a trust model over an adhoc routing protocol in a real adhoc testbed.

A Generalized Trust Framework for Mobile Ad Hoc Networks

Mobile ad hoc networks (MANET) are formed when two or more nodes come within the communication range of each other. Since the wireless range is very short, all the nodes in the network have to extend their complete co-operation for efficient functioning of the network. This paper proposes a generalized trust framework for any ad hoc routing protocol to curb selfish and malicious nodes in a MANET. The trust relationships existing between the nodes determine the routing path to be taken for data transfer. The trust framework is combined with any MANET routing algorithm. The performance analysis of this framework is currently done with two reactive protocols. Jointly, they form a trusted network to curb various attacks originating in the ad hoc network. This type of a trusted framework established in a MANET, would be most suited for tactical environments.

Energy Aware Data Sharing in Mobile Ad Hoc Networks

In mobile ad hoc networks (MANET) ,computation devices are battery powered. Limited energy in battery constrains the computation and communication of each device. Hence services like sharing a data or information among users becomes a challenging issue in critical environments like military applications, rescue operations etc. To overcome this, we have proposed a replication model which replicates shared data in suitable nodes. It addresses how data sharing can be done effectively by periodically checking the remaining energy of each node that holds the replica. If the remaining energy falls below a threshold level, replica can be relocated to appropriate nodes that has the maximum energy. Therefore our proposal ensures file availability, improves the network life time, decreases query response time, increases energy utilization, decreases number of packet drops due to battery depletion of a node.

Applicability of sub graph centrality to improve data accessibility among peers in MANETs

Data sharing plays an essential role in many of the mobile ad-hoc network (MANET) applications that exhibits collaborative behavior. In such applications, replication is used as a foremost and fundamental technique to improve data availability. However, due to the dynamic nature of the network, data replication becomes more intricate in MANET. To alleviate this problem, we have proposed a mechanism which not only enhances data accessibility, replicates data in a minimum number of nodes, relocates shared data on the prediction of mobility of replica holder and in addition, data can be accessed by any node in a minimum number of hops. In our approach, we have prefaced mathematical concept known as minimum dominating set and sub graph centrality principle to decide the number of replicas both in static and dynamic environment. Simulation results when compared with the existing mechanisms shows that the response time or data access delay is reduced, client can access the data from the server in a minimum number of hops, and consequently the number of forwarded messages to access the data are greatly reduced thus making our network energy efficient.

Design of Penta-Band Low Noise Amplifier

A new Penta-Band Low Noise Amplifier (PB-LNA) for vehicular communication applications that works simultaneously at navigational frequencies viz., 1.2 GHz, 1.5 GHz and wireless Communication frequencies viz., 2.4 GHz, 3.3 GHz and Dedicated Short Range Communication frequency (DSRC), 5.8 GHz is designed and analysed. Frequency transformation method is adopted for the input matching network of the designed PB-LNA. The output matching circuit is designed with a LC matching network by applying load-pull methodology. The LNA is unconditionally stable for the desired frequency bands. The power gain of PB-LNA is in the range of 10 dB to 12 dB. Noise figure (NF) below 2dB is achieved in the band of interest.

Penta-band active integrated spiral antenna

This paper describes the design of novel penta-band active integrated spiral antenna for vehicular wireless applications. Frequency transformation method is adopted for the input matching network of the penta band low noise amplifier (LNA) and by using load-pull methodology; the output matching circuit is designed with simple LC matching network. The designed active integrated spiral antenna operates at navigational frequencies 1.32 / 1.5 GHz, wireless communication frequencies 2.4 / 3.3 GHz and Dedicated short range communication frequency 5.8 GHz.