M. Lutfar Rahman

Network architecture and security issues in campus networks

Network architecture with its security is a growing concern in the present time. A campus network faces challenges to address core issues of security which are governed by network architecture. This paper is mainly targeted towards campus networks which deliver required security. This is essential because, it prevents the institution from suffering any significant attacks associated with network. A university network has a number of uses such as teaching, learning, research, management, e-library, and connections with the external uses. Therefore, network architecture and its security are vital issues for any university. In this work, a network infrastructure is proposed on the basis of the practical and experimental requirements. The proposed network infrastructure is realizable with adaptable infrastructure.

A Geometric Model to Reduce Interference Computations in Simulation of Large Ad hoc Networks

Simulation of wireless networks has recently drawn considerable attention in the area of abstraction. Simulation is a precious tool used to model complex systems where the desired network size is large in scale. For large mobile ad hoc networks, the most computation intensive tasks in simulation are computing interference and determining which receivers are in range of a transmitter. In both cases, O(N2) physical layer calculations are required for a wireless system of N nodes, which scales poorly. In this paper, a geometric model, minimal rectangular coverage area is devised for the optimization of the complexity of interference computations in simulations of wireless mobile ad hoc networks. This method lessens the number of unaffected nodes by considering less area as affected by transmission range, which exists outside the transmission range of a transmitter. However, the experimental results suggest that this geometric model reduce the affected coverage area 12.5% - 78.15% than existing grid based algorithm used in current version of NS2. This paper also discusses about the efficiency considerations of the algorithm in detail.

Geometric model for minimizing node discovery load in network simulators for large ad hoc networks

The area of wireless ad hoc networking has been receiving increasing attention among researchers in recent years. NS2 is the most common simulator which is used to simulate wireless ad hoc networks. But, NS2 does not scale the simulation well, where there are a large number of nodes in a simulation area. In this paper a geometric approach is proposed targeting the optimization of the area that exists between the approximated area for processing and the area outside the coverage area of a transmitter. Thus, this proposed algorithm reduces the number of unaffected nodes (considering the transmission signal range), which are currently considered by the NS2 simulator for checking, whether the node resides inside the transmission area or not. The current version of NS2 uses a block based optimization but the algorithm, proposed here, reduces the coverage area of the blocks near the boundary of the transmission range, targeting the improvement of the performance of NS2 for the simulation of large ad hoc networks. These theoretic assumptions have been followed by extensive realistic test conditions for generating a set of sensible result-set for achieving the optimum from the proposed physical propagation model to facilitate NS2 with a faster simulation performance for larger wireless ad hoc mobile network. The proposed approach saves the coverage area from at least 12.5% upto 78.15% than in existing solution.

Tape Transport Mechanism Control For a Magnetic Tape Recorder/Player Used for High-Speed Data Transfer

In this paper an attempt is made to develop an efficient tape transport mechanism required for high-speed data transfer. The mechanism is controlled by a microcomputer, which is a party in the data transfer operation. A commercially available transport system has been adopted for this purpose, with simple modification. During data search operation the tape speed is faster than the speed in normal Read/Write operation. At the same time, the Read/Write head position is adjusted in accordance with the tape speed. The system includes facilities for detecting the beginning and the end of the tape, and switching off the amplifier for read and write operation. Taking into account the delay for signal transfer and the time for motor torque, a tape motion velocity profile has been generated. This is used to obtain start, stop and interblock gap length.