C. K. Nagpal

Reachability Analysis of Mobility Models under Idealistic and Realistic Environments

The mobility models are used to represent the unpredictable movement pattern of the nodes in Mobile Ad-hoc Network (MANET) and give us an idea regarding their location, velocity and acceleration change over time. These models are used for simulation purpose in standard software tools such as QualNet, ns-2 etc. This paper evaluates the performance of routing protocols for mobility models such as Random Way Point (RWP), Random Walk (RW) and Random Direction (RD) under idealistic and realistic conditions based on a parameter termed as Probability of Reachability (POR). The POR is defined as the fraction of reachable routes to all possible routes between all pairs of sources and destinations. For this purpose a simulator is designed in MATLAB. We observe a marked difference in value of POR under idealistic and realistic conditions.

Towards realistic performance evaluation of Mobile Ad Hoc Network

Mobile Ad-Hoc Network (MANET) is a self-configuring network of mobile nodes connected by wireless links to form an arbitrary topology without the use of existing infrastructure. In order to facilitate communication between a pair of nodes, routing protocols are used. The performance of routing protocols is evaluated using simulation tools such as QUALNET, NS-2 and MATLAB etc. Simulation tool provides researchers with a number of significant benefits, including repeatable scenarios, isolation of parameters, and exploration of a variety of metrics. We wish to make these simulations more realistic for ad hoc network. To do the same different shapes such as square, elliptical, circular and rectangular of the simulation region were taken. In addition to different shapes, we used the concept of obstacle. These obstacles restrict node movement as well as obstruct the communication path between nodes. Simulation results show that for same number of nodes deployed having equal areas and with different shapes the throughput will have inverse relationship with perimeter. The result can be very useful while designing a routing protocol.

Impact of area's shape on MANET performance

The Mobile Ad hoc Networks (MANETs) are normally deployed in the disaster affected areas where there is a big damage to infrastructural resources or in the military operations in the remote areas, where the infrastructural resources are virtually nonexistent. The performance of these networks is known to be dependent upon various parameters such as transmission range, mobility, bandwidth and residual power of the nodes, and the network size. Literature provides the study of the impact of these parameters on the MANET performance. This paper provides the impact of a new parameter, the shape of the area where the ad hoc network is to be deployed, on the performance of ad hoc networks through simulation in MATLAB.

A Novel Transmission Power Efficient Routing in Cognitive Radio Networks Using Game Theory

Owing to frequently increasing demand of wireless communication technology, the problem of spectrum shortage arises. To overcome this, Cognitive Radio (CR) came into play. CRs use the available vacant spectrum of primary users intelligently. CRs use these spectrum holes opportunistically by changing their transmission parameters. To model the performance of a wireless network, game theory has been used due to its capability to model individual, independent decision-makers. Game theory can be used in any network at various layers, to model its behavior and performance. To send data between any two nodes in network, we need a routing protocol. We aim to find out a transmission power-aware routing algorithm which routes the message packets efficiently within the network, while maximizing the overall throughput of the system. And then we compare its performance with shortest path and minimum transmission power routing scheme. Implementation is done in MATLAB-9.0.

Publicly verifiable watermarking scheme for intellectual property protection using quantum Chaos and bit plane complexity slicing

Intellectual Property such as music, painting, videos and other similar works being broadcasted on web need to be protected against copyright infringement to ensure the rights of their legitimate owners. Moreover, their users must also be sure of the originality of these artefacts. Both these problems can be solved through proper authentication on behalf of the creator. For this purpose, various publicly verifiable watermarking schemes have been available in literature. Recent proposal, in this domain, is based on chaos theory and Secured Hashing Algorithms SHA-2. Due to tremendous growth in the availability of Intellectual Property on the web and associated breaches it becomes a mandatory requirement to update these authenticating schemes. This paper proposes the usage of some more secure, reliable and efficient components in watermarking schemes than being used at present. Proposed changes include the deployment of encryption scheme based on Quantum Logistic maps instead of current Chaos encryption based on peter de-jong map, in order to optimise randomness, correlation and time complexity. For better security and efficiency in hardware implementation SHA-3 is a better choice than SHA-2. Data embedding can be done in regions where imperceptibility is quite high. The proposed changes can result in the creation of more reliable and efficient system. To test the hypothesis, proposed mechanism has been implemented in MATLAB-16a and various performance metrics such as correlation coefficient, PSNR, UIQI, SSIM have been measured. The results show that proposed scheme outperforms its counterpart in terms of all the performance metrics.

An efficient hybrid security mechanism based on chaos and improved BPCS

Commonly used security mechanisms such as cryptography and steganography suffer from weaknesses when used in a standalone manner. Extra efforts in the form of additional permutations/diffusions etc. result in higher ciphering/deciphering time complexity. Thus, there is a requirement for a security mechanism(s) which can provide adequate security without putting a considerable burden on ciphering/deciphering time complexity. This paper is an effort in this direction. The paper proposes a hybrid mechanism that employs chaotic based encryption scheme to encrypt data and an improved Bit-Plane Complexity Segmentation Steganography algorithm to embed the data. The proposed mechanism uses two new complexity measures to differentiate between noisy regions and simple ones appropriately. The scheme was implemented in MATLAB, and the simulation results show that the proposed mechanism has high embedding capacity, high security with a moderate decrease in PSNR value and is computationally fast.

A novel routing strategy for cognitive radio ad hoc network based on Sugeno fuzzy logic

In cognitive radio networks, a secondary user (SU) is dependent upon the spectrum, of varied frequency, temporarily vacated by primary users (PU) thereby making it quite a challenging task to design a protocol for finding a reliable and efficient routing path. To address the issue many routing schemes have been proposed based upon Mamdani type fuzzy inference system (FIS) to create a human intelligence analogy. The Mamdani type fuzzy inference mechanism is unable to simultaneously optimise multiple quality of service (QoS) parameters. This paper proposes a routing scheme based upon the Sugeno type fuzzy inference system (SFIS) that handles the continuously changing input parameters in quite effective manner and provides an effective performance with respect to multiple QoS parameters. The proposed routing scheme has been implemented using Matlab-9.0 and simulation results showed that the paths selected using this scheme are much more efficient than the paths selected by other routing schemes.

Semantic similarity between terms for query suggestion

To retrieve semantically related documents with the query submitted by the user has always become a challenging task. An efficient assessment of semantic similarity is of critical importance in the area of information retrieval and web mining so as to associate the query with its associated documents. However their cannot be any accurate measure for semantic similarity as its domain is spread not only over individual words but also on the terms, phrases, sentences, entity and sometime even over whole of the document. To calculate semantic similarity between terms based on synsets a new method is proposed in this paper in which synsets are derived using online resources. The advantage of the proposed work is that, the semantic similarity between terms is calculated that helps in query suggestion or replacement of one query with the most appropriate query.

Journey of Web Search Engines: Milestones, Challenges & Innovations

Past few decades have witnessed an informat ion big bang in the form of World Wide Web leading to gigantic repository of heterogeneous data. A humble journey that started with the network connection between few computers at ARPANET project has reached to a level wherein almost all the computers and other communication devices of the world have joined together to form a huge global in formation network that makes availab le most of the information related to every possible heterogeneous domain. Not only the managing and indexing of th is repository is a big concern but to provide a quick answer to the user‘s query is also of critical importance. Amazingly, rather miraculously, the task is being done quite efficiently by the current web search engines. This miracle has been possible due to a series of mathematical and technological innovations continuously being carried out in the area of search techniques. This paper takes an overview of search engine evolution from primitive to the present .