In this paper, the capacity of stratospheric cellular communications is improved by optimizing the amplitude feeding of the concentric rings array (CRA). The weighting profile of this array is chosen to be a cosine function raised to some power to control the beam pattern used in the cellular coverage. The power of this function is optimized to reduce the resulted sidelobe levels which increase the carrier-to-interference ratio (CIR) within the cells. It is found that increasing the power of the cosine function will reduce the sidelobe levels especially at lower number of elements in the innermost ring with a minor increase in beamwidth. For an innermost ring of 3 elements in a 10 rings CRA, a sidelobe level of 45 dB can be obtained below the mainlobe level. The simulation results show that a CIR of up to 38dB can be achieved and a minimum of 28dB at the cell borders is guaranteed with a 0.95 coverage ratio.

A botnet is a group of compromised computers—often a large group—under the command and control of a malicious botmaster. Botnets can be used for a wide variety of malicious attacks, including spamming, distributed denial of service, and identity theft. Botnets are generally recognized as a serious threat on the Internet. This paper discusses SocialNetworkingBot, a botnet we have developed that uses Twitter for command and control. In SocialNetworkingBot, the botmaster tweets commands that are acted on by the individual bots. We discuss the functionality and implementation of SocialNetworkingBot, as well as a small-scale experiment that we have conducted. The botnet presented here is intended to serve as a proof of concept and a platform to facilitate further research.

The problem of scheduling dependent tasks (DAG) is an important version of scheduling, to efficiently exploit the computational capabilities of grid systems. The problem of scheduling tasks of a graph onto a set of different machines is an NP Complete problem. As a result, a number of heuristic and meta-heuristic approaches are used over the years due to their ability of providing high quality solutions with reasonable computation time. Discrete Particle Swarm Optimization is one such meta-heuristic used for solving the discrete problem of grid scheduling, but this method converge to sub optimal solutions due to premature convergence. To deal with premature convergence, in this paper we proposed the design and implementation of hierarchical discrete particle swarm optimization (H-DPSO) for dependent task scheduling in grid environment. In H-DPSO particles are arranged in dynamic hierarchy where good particles lying above in hierarchy are having larger influence on the swarm. We consider the bi-objective version of problem to minimize makespan and total cost simultaneously as the optimization criteria. The H-DPSO based scheduler was evaluated under different application task graphs. Simulation analysis manifests that H-DPSO based scheduling is highly viable and effective approach for grid computing.

This work describes the neural network technique to solve location management problem. A multilayer neural model is designed to predict the future prediction of the subscriber based on the past predicted information of the subscriber. In this research work, a prediction based location management scheme is proposed for locating a mobile terminal in a communication without losing quality maintains a good response. There are various methods of location management schemes for prediction of the mobile user. Based on individual characteristic of the user, prediction based location management can be implemented. This work is purely analytical which need the past movement of the subscriber and compared with the simulated one. The movement of the mobile target is considered as regular and uniform. An artificial neural network model is used for mobility management to reduce the total cost. Single or multiple mobile targets can be predicted. Among all the neural techniques multilayer perceptron is used for this work. The records are collected from the past movement and are used to train the network for the future prediction. The analytical result of the prediction method is found to be satisfactory.

Long Term Evolution (LTE), the standard specified by 3GPP on the way towards the fourth generation mobile networks, is intended to deliver high speed data and multimedia services to next generation mobile users. The Radio Resource Management (RRM) plays a very crucial role in managing limited radio resources to enhance system's data rate and to ensure quality of service (QoS) provisioning in both uplink and downlink. LTE downlink scheduling is a RRM entity that is responsible for the allocation of shared radio resources among mobile user equipment (UEs). One of the challenges that need to be addressed in downlink scheduling algorithms is to provide higher spectral efficiency with fairness ensured to all its users. This paper proposes a novel downlink scheduling algorithm which balances its performance between efficiency (in terms of throughput) and fairness to users. The algorithm makes use of Assignment Model for resource allocation to all the selected users during each Transmission Time Interval (TTI). The proposed algorithm is simulated and the simulation results are compared with three techniques proposed in literature. The simulator results show that the new algorithm balances well between throughput and fairness.

In present epoch, secure online access to enterprises resources is very important for any organization. To protect valuable data become one of the big challenge for today's business as enterprise customers or clients involved in business-to-customer (B2C) and business-to-business (B2B) e-commerce need to feel that their transactions are secured from system hackers. Biometric technology provides a solution to this problem in enterprise network security. In this article we enhance the security of online transaction using secure and unique biometric template. The uniqueness of our process is that we store biometric template and password together in encrypted form both without the fusion of score level and decision level, which leads a successful way to combine multiple technologies, different from earlier methods. Password hardened biometric system helps to generate many different secure biometric templates for the same biometric system. It also generates unique biometric templates for multiple biometric systems from the same biometric trait.

Fault attacks are powerful and efficient cryptanalysis techniques to find the secret key of the Advanced Encryption Standard (AES) algorithm. These attacks are based on injecting faults into the structure of the AES to obtain the confidential information. To protect the AES implementation against these attacks, a number of countermeasures have been proposed.
In this paper, we propose a fault detection scheme for the Advanced Encryption Standard. We present its details implementation in each transformation of the AES. The simulation results show that the fault coverage achieves 99.999% for the proposed scheme. Moreover, the proposed fault detection scheme has been implemented on Xilinx Virtex-5 FPGA. Its area overhead and frequency degradation have been compared and it is shown that the proposed scheme achieves a good performance in terms of area and frequency.

Modern microprocessors are loaded with a lot of performance optimization features. Single Instruction Multiple Data (SIMD) instruction set feature specially designed for improving the performance of multimedia applications is one among them. But most of the encryption algorithms do not use these features to its fullest. This paper discusses various optimization principles to be followed by encryption algorithm designers to exploit the features of underlying processor to the maximum. It also analyses the performance of four eSTREAM finalist stream ciphers – HC-128, Rabbit, Salsa 20/12 and Sosemanuk – under various methods of implementation. Scope of implementing these stream ciphers using SIMD instructions is examined and improvement in performance achieved by this implementation has been measured. Modifications in the algorithm which provide further improvement in performance of these ciphers are also studied.