Earticle

A mobile ad hoc network (MANET) is a system of wireless mobile nodes with routing capabilities, any group of them capable of forming an autonomous network that requires no infrastructure and is capable of organizing itself into arbitrary changeable topologies. A MANET needs a special mechanism to bear with its ad hoc behaviour. In this paper, we are considering a set of heterogeneous nodes in MANETs, which are having different packet size, different security mechanisms and different communication speed etc. The architecture we propose comprises of two main building blocks, namely security management and communication management across all heterogeneous nodes in the scalable and non scalable MANETs. In this network each node does not understand security techniques of each other nodes, because, there could be different encryption techniques, packet size, protocol etc, hence this network is fully dependent on middleware of MANETs. The proposed solution provides security solutions in middleware for scalable and non scalable MANETs and it has found that the malicious node would not be a part of communication in the network through simulation. This technique is very effective for security issues in heterogeneous nodes in MANETs.

A communications network that is capable of storing packets temporarily in intermediate nodes, until the time an end-to-end route is re-established or regenerated is known as a delay tolerant network/s, in short, DTN. This paper aims to detail basic & general aspects specific to information needs in DTN routing and present classification chart. We start with evolution of some relevant routing objectives and issues since their inception, discuss in some detail routing types, groups and classifications. Our study culminates in identification of various schemes and techniques that will provide an insight and help us to exploit the delay and effectively utilize the time in a judicious manner to help improve the efficiency of information exchange in a DTN network. The basic objective is to utilize efficiently this temporal-period or adhoc-period by opportunistically establishing connectivity - in a strategic manner, to exchange information across locally distributed resources, thus making optimal use of available network resources and enhancing the efficiency of information exchange.

This paper presents a new implementation and evaluation of digital signature for mobile devices. This digital signature system takes into account the device limitations and thus generates a functional digital signature. Its efficiency is described and justified along the paper. It also presents a case study that allows the evaluation of the device implication in the key generation that takes part of the digital signature process.

The GPS has been applied in many fields of knowledge. The sophisticated technology on GPS has contributed many findings of new alternative and facilitating the end-user many of ease, specifically on position tracking matters and its accuracy is also utilized to navigate a path of directions of travel’s destination. Usability of GPS to track coordinates of places precisely is also able to be utilized to assist a Moslem traveler who goes on a trip which has not been visited yet to find the nearest mosque to perform the prayer. However, not many techniques have been proposed for a Moslem traveler for Mosque tracking system and how to resolve the geometrics dilution of precision problematic on signal retrieving while tracking the mosques is still an issue. This paper presents development GPS on tracking nearest mosque surrounding visited area with geometric dilution solving and optimization of GPS track using mobile application software embedded with prayer time’s synchronization on the mobile application. The proposed technique could not leave 5 times prayer and somehow confronts many difficulties to seek the nearest mosque to perform the worshiping in new areas.

Mobile radio channel simulators are essential for repeatable system tests in the development, design, or test laboratory. Field tests in a mobile environment are considerably more expensive and may require permission from regulatory authorities. Because of the random, uncontrollable nature of the mobile propagation path, it is difficult to generate repeatable field test results. The Nakagami model can be used to test the performance of radios in a mobile environment in the lab, without the need to perform measurements whilst actually mobile. The mobile fading simulation can also if required be replicated, and the effects can be varied according to the ‘velocity’ of the mobile receiver. This allows the comparison of the performance of different receivers under standardized conditions that would not normally be possible in actual mobile testing situations. In this paper, two techniques that are capable of generating correlated Nakagami channels with arbitrary fading parameters are proposed. Basically our approach is to generate Nakagami RVs from the square root of directly generated correlated Gamma RVs (not from sum of squares of Gaussian RVs).

The present work is dedicated to study attacks and countermeasure in MANET. After a short introduction to what MANETs are and network security we present a survey of various attacks in MANETs pertaining to fail routing protocols. We present the different tools used by these attacks and the mechanisms used by the secured routing protocols to counter them. We also study a mechanism of security, named the reputation, proposed for the MANETs and the protocol which implements it as well as its vulnerabilities. Our work ends with a proposal to fend off some of these attacks like Blackhole cooperative, Blackmail, Overflow, Selfish and an implementation of this solution on a compiler of C named Dev.-C++ in order to make comparative tests with the mechanisms already proposed.

PCRF is defined as an entity used for policy and QoS control for a converged network by 3GPP. Though there are elaborate procedures defined for policy and QoS control for session establishment, modification and deletion, however, there are no procedure defined which can help in improving the Quality of Experience (QoE) for an established session. The current paper focuses on tracking actual QoS which is being experienced by the user (termed as QoE in this paper) and defines procedures for Policy control entities in a 3GPP defined setup for RTP based Video and non-Voice Media session.

Energy level performance of three packet delivery schemes in a Wireless Sensor Networks (WSNs) over fading channels is evaluated. Effects of two short term fading such as Rayleigh and Rician on packet delivery schemes are evaluated. Three different information delivery mechanisms are considered using regenerative relays with or without error correction capability. In all the three schemes, message packet is sent on hop-by-hop basis. In scheme I, message is corrected for error at every hop while in the other two schemes; message is corrected at the destination. Energy consumption for successful delivery of a data packet for each mechanism is evaluated and compared under several conditions of node density, bit rate and transmit power. Energy efficiencies of different retransmission schemes are evaluated. Further an optimal packet length based on energy efficiency is derived in each transmission scheme. Effects of different level of severity of Rician fading on energy efficiency and energy consumption are also investigated. Impact of optimal packet size on total energy expenditure is analyzed.

A compact two element MIMO (Multiple Input Multiple Output) system is proposed using a multi slot patch antenna employing polarization diversity. The proposed MIMO system offers improved bandwidth, return loss and isolation characteristics. The system resonates at 5.35GHz and 5.81GHz frequencies for VSWR≤2, which can be used for 4G & WiMAX applications. The simulation results of return loss, mutual coupling, correlation coefficient and gain are presented. The channel capacities for the developed system are also estimated for indoor propagation.