P. Balamuralidhar

A mechanism for detection of gray hole attack in mobile Ad Hoc networks

Protecting the network layer from malicious attacks is an important and challenging security issue in mobile ad hoc networks (MANETs). In this paper, a security mechanism is proposed to defend against a cooperative gray hole attack on the well known AODV routing protocol in MANETs. A gray hole is a node that selectively drops and forwards data packets after it advertises itself as having the shortest path to the destination node in response to a route request message from a source node. The proposed mechanism does not apply any cryptographic primitives on the routing messages. Instead, it protects the network by detecting and reacting to malicious activities of any node. Simulation results show that the scheme has a significantly high detection rate with moderate network traffic overhead.

QoS-enabled group communication in integrated VANET-LTE heterogeneous wireless networks

Ubiquitous integration of high-speed WLANs with wide-range 3GPP systems results in the service extension of the backbone cellular network. This paper envisions such heterogeneous wireless network architecture by integrating IEEE 802.11p VANETs with 3GPP LTE to achieve seamless data connectivity for uninterrupted multimedia sessions amongst spatially-apart vehicular clusters. Issues on cluster head-based multicasting and QoS are explored in this paper. An adaptive multi-metric Cluster Head (CH) election mechanism is proposed to manage the VANET sub-clusters. In addition to this, construction of a 2-hop virtual overlay mesh-based shared multicast tree for lower-level multicasting within VANETs is discussed. Following this, the process of VANET-LTE upper-level communication is detailed, addressing the issues of CH and gateway handover, and resource allocation of the LTE eNB. The envisioned architecture enables the LTE to effectively schedule multimedia sessions based on the service requirements of the VANET gateways, thus satisfying QoS. Requisite simulation results are presented to evaluate the integrated network.

A distributed protocol for detection of packet dropping attack in mobile ad hoc networks

In multi-hop mobile ad hoc networks (MANETs), mobile nodes cooperate with each other without using any infrastructure such as access points or base stations. Security remains a major challenge for these networks due to their features of open medium, dynamically changing topologies, reliance on cooperative algorithms, absence of centralized monitoring points, and lack of clear lines of defense. Among the various attacks to which MANETs are vulnerable, malicious packet dropping attack is very common where a malicious node can partially degrade or completely disrupt communication in the network by consistently dropping packets. In this paper, a mechanism for detection of packet dropping attack is presented based on cooperative participation of the nodes in a MANET. The redundancy of routing information in an ad hoc network is utilized to make the scheme robust so that it works effectively even in presence of transient network partitioning and Byzantine failure of nodes. The proposed scheme is fully cooperative and thus more secure as the vulnerabilities of any election algorithm used for choosing a subset of nodes for cooperation are absent. Simulation results show the effectiveness of the protocol.

An Improved Time-of-Arrival Estimation for WLAN-Based Local Positioning

Local positioning, particularly in indoor environments, poses challenges that are not faced by global and terrestrial positioning systems. Many a times, it is cost effective to build these localization schemes on the existing wireless local area networks (WLANs). This paper presents a novel time-of-arrival estimation technique for IEEE 802.11a WLAN system, which provides better accuracy than the traditional correlation-based scheme.

On the architecture of vehicle tracking system using wireless sensor devices

Integration of different technologies potentially provides support to wide variety of applications and systems with vastly varying requirements and characteristics. Vehicle tracking system is one of such applications possible by embedding wireless sensor devices on the vehicles. The most of the state-of the-art technology uses GPS (Global Positioning System) for tracking vehicles which is very expensive. The focus of the proposed vehicle tracking system is to track the desired vehicle with low-cost, effective implementation as in contrast to the existing high-cost tracking systems. In this paper, we present architecture for vehicle tracking system using wireless sensor technology. We have defined the packet structure for communication between the nodes. Certain issues that arise during implementation are discussed. To investigate our proposed design towards implementation, we have performed simulations for different scenarios under certain realistic conditions using Qualnet network simulator. The results from the analysis and evaluation through simulations provide general design guidelines to implement the proposed solution.

Estimating true speed of moving vehicle using smartphone-based GPS measurement

The Global Positioning System (GPS) receivers are now an integral part of smartphones. However, phone based GPS measurements display much less accuracy as compared to professional grade receivers. On the other hand, the deep penetration of smartphones in consumer market offers opportunity for customizing new solutions. One such possible application is targeted towards identifying risky driving profile for the purpose of customizing auto-insurance premium. For this to be successful, one needs to estimate the true vehicle speed. In this paper, we have presented a method to estimate the true speed of a moving vehicle derived solely from GPS measurements. In this case the accelerometer sensors are not used in conjunction with GPS measurement. The results are compared with OBD2 speed measurement. The proposed method computes a better estimate of vehicle speed, where correctness is measured relative to OBD2 measurement.

SpreadStore: A LDPC Erasure Code Scheme for Distributed Storage System

A wide proliferation of distributed storage systems call for more robust and efficient systems than regular replication based storage systems. The Low density parity check (LDPC) codes have become a popular alternative to traditional Reed-Solomon (RS) erasure codes due to their low computational complexity. In this paper we propose, Spread Store- a distributed storage system based on LDPC code. Also, a brief analysis is made by examining different LDPC codes from the perspective of their efficiency and erasure handling capabilities.

Polarization diversity improves RSSI based location estimation for wireless sensor networks

Signal strength based wireless location estimation suffers accuracy in indoor environments since the distance to RSSI (received signal strength indicator) function is not monotonic and gives multiple distance estimates for a specific signal strength value. In this paper an advancement of the existing estimation techniques is proposed by establishing the use of polarization diversity in getting robust location estimation. The measurements done in indoor environment clearly bring to fore the need to compute the signal strengths on different polarization vectors of radiated E-field, for prediction of location of wireless communication nodes with a better accuracy. Experiments conducted for both line-of sight and non-line of sight cases show that an optimal weighted sum of the respective signal strengths for different polarizations lead to a monotonic path loss expression which can be used for predicting the locations even with minimal initial training sequence. This novel approach enables precision indoor localization with a minimal set of measurements by exploiting the easily available RSSI information

Effect of Check Node Processing on the Performance of Message Passing Algorithm in the Context of LDPC Decoding for DVB-S2

Low density parity check (LDPC) codes have become very popular in recent times due to their capacity approaching performance and are considered in the next generation digital video broadcasting DVB-S2 standard. This paper presents few results and observations obtained when some of the existing decoding algorithms are studied in the context of the standardized codes. These results with further consolidation will facilitate to arrive at the right algorithm for decoder design

A Scheme of Certificate Authority for Ad Hoc Networks

The attractiveness of the wireless ad hoc networks lies in the fact that these networks are self-organized: the hosts constituting the networks can communicate with each other without reliance on any centralized or specified entities such as base stations or access points. With these networks finding more applications, the need for adequate security mechanism is increasingly becoming important. Key management is an essential cryptographic primitive upon which other security protocols are built. However, most of the existing key management schemes are not feasible in ad hoc networks because public key infrastructures with a centralized certification authority are hard to deploy there. In this paper, we propose and evaluate a security mechanism based on distributed certification authority based on threshold cryptography that is suited to wireless ad hoc networks. A collection of nodes acts as the certificate authority and provides the certification service. The feasibility of the proposed scheme is verified by some simulation studies. The results show the effectiveness of the scheme.The institutional effect is used to explain and predict MBA students decisions to adopt e-learning in their studies. A composite model including four constructs, namely, perceived usefulness, perceived ease of use, sense of popularity and convenience, were formed and tested in the empirical study. This study found that normatively appropriate and taken-for- granted structure of institutions were the most important principles for adult students when making e- learning decisions.