Shahida Rafique

FPGA realization of multipurpose FIR filter

A multipurpose FIR filter has been designed and realized by field programmable gate arrays (FPGA) for real-time filtering applications. The design can accomplish an arbitrary filter frequency response and variable filter order up to 127. The coefficients are computed through the Hamming windowing technique. The model is capable of performing filtering operations, like lowpass, highpass, bandpass and bandstop based on selection that is embedded into the design. The filter is set to 8-bit signed data processing. Linear constant coefficient difference equation (LCCDE) has been used to filter the input data in time domain. The design is coded with VHDL to cope with the parallelism of digital hardware. Simulation, compilation and synthesis have been done to verify the validity of the design outputs. To test the correctness of the design the observed output is compared with the calculated output results from MATLAB implementation that confirms the effectiveness of the design.

Use of LTE for the Interoperability between Different Generations of Wireless Communication

This paper looks potential approaches to interoperability as well as inter-technology mobility using Long Term Evolution (LTE) between different generations of wireless communication. Focus is given on how these approaches can be used in interoperable service deployment, access technology integration, service continuity and smooth migration to LTE by maximizing the use of legacy networks coverage. One of the most important interoperability criterions is the handover latency. Using NCTUNS6 simulator it is shown that LTE (4G) provides less handover latency in comparison to that of other generations of wireless communication system for homogeneous environment.

Interoperability of Wireless Networks Based on Layer Modification and LTE with 4G

Future generation of wireless communication systems are envisioned to offer higher data rates, higher mobility support, transparent and seamless communication. These requirements open potentials for the operators to increase their service portfolio and for the users to experience context-rich and personalized services. Consequently the interoperability between different wireless network platforms emerges as a crucial necessity. Here focus is given to the significance of the network interoperability aspect based on layered approach and its role in the development towards 4G.This paper gives an overview of the major and differentiating features of 4G from other generations. Attention is also paid to the interoperability provided by LTE.

Interoperability of Wireless Networks with 4G Based on Layer Modification

Fourth generation wireless communication systems feel the necessity of transparent and seamless user roaming with end-to-end connectivity. These systems also demand higher data rate, higher mobility support and QoS guarantees due to rapid development of wireless and mobile networks. These requirements open potentials for the operators to increase their service portfolio and for the users to experience context-rich and personalized services. Consequently the interoperability between different wireless network platforms emerges as a crucial necessity. Here focus is given to the significance of the network interoperability aspect based on layered approach and its role in the development towards 4G. This paper also gives an overview of the major 4G features and differentiating characteristics from other generations.

Analysis of real-time multimedia traffic in the context of self-similarity

Multimedia networks are now providing versatile services to meet different types of subscriber needs including voice, video, data, etc. Voice and video conferencing applications over these IP networks have already gained wide acceptance in todaypsilas end-user communities. The traffic characteristics and intensity as a function of time, geographic source can be realized by observing traffic distribution. Multimedia traffic has characteristics very different from Poisson characteristics, generating high rate data at one time and low rate data at another. Variable bit rate (VBR) real-time applications such as compressed video and audio and also the data sources tend to generate bursty traffic patterns and exhibit certain degree of correlation between arrivals and show long-range dependence in time i.e. self-similarity [1, 2, 3, 4, 5]. Therefore, it is important to identify and characterize network traffic flows to analyze network performance. In the present work the analysis of real time audio and video streaming traffic, colleted from the videoconferencing session of an enterprise high-speed hybrid multimedia network, has been done in the context of self-similarity.

Complete bandgap in two dimensional photonic crystals with square bravais lattice

Two- dimensional (2-D) photonic crystals (PhCs) of square lattice have been investigated to find the complete photonic bandgap. Band diagram calculations have been performed using the simulator “PWE band solver” of the software package optiFDTD™, based on plane wave expansion method. GaAs dielectric rods in air background with four different shapes have been considered. Filling fraction, rod/air hole orientation angle and material dielectric constant have been varied. It has been found that PhCs with square dielectric rods have the largest gap; the gap-midgap ratio is 5.39% when filling fraction ƒ = 0.47 and orientation angle Θ = 0°. It has also been found that the photonic band gap behavior for other types of material e.g. Si, Ge are similar to the GaAs and these materials can exhibit complete photonic band gap.

Integration of GPS-24, GEO & LEO: Modeling, receiver selection algorithm and performance analysis for navigation

In this research study, an integrated network of GPS-24, GEO and LEO has been designed to improve the worst-case precision values. The precision values to be realized by the receiver with an algorithm have been proposed. It is expected that a good worldwide availability of best four selected orbiting satellites among many having maximum coverage would be the preferred constellation for navigation. A new approach for minimum dilution of precision (DOP) determination using integrated constellation is developed. Satellite visibility through GPS receiver has been investigated using complex simulations of failure scenarios by giving shadow effect. This work is to improve coverage and satellite visibility for accurate, flexible, fast and cost-effective navigation purpose using integrated network. Using a 3-step algorithm a set of best four satellites selection is possible by minimum calculation by determining minimum DOP. A measurement for positioning, satellites at low elevation angles and at high elevation angles has been compared. The proposed model and algorithm will hopefully be used for navigation purposes in the worst case. The system can also be used academically as well as for commercial purpose.

An approach to realize a quantum NOT gate through optical implementation

Transverse modes of electromagnetic fields are proposed to be encoded as qubits for the implementation of a quantum NOT gate. The possibility of this encoding scheme was designed, simulated and verified through rigorous numerical analyses using the Beam propagation method. The proposed gate has the potential of being more compact and easily realizable than some other optical implementation proposals since it is based on planar light wave circuit technology and can be constructed very easily by using a planar light wave technology. The Results proved that the design is able to perform the required NOT transformation and the conclusion was reached that the model was a successful implementation of a quantum NOT gate.

Design, simulation and realization of a highly efficient wireless sensor network

A sensor network has greater potential for performance improvement, due to its versatility and the ability to monitor a large geographical area. Recent advancement in wireless communication and electronics has enabled the development of low power consumption and low cost sensor network. There are different technical issues that researchers are currently resolving. Most of the attention however has been given to the routing protocols since they might differ depending on the application and network architecture. In this paper, the current state-of-art of sensor networks is captured. An energy efficient design proposal is suggested considering physical layer, data link layer and network layer. The simulator OMNeT++ was employed to evaluate the throughput, number of packet collisions of the network, and the network node duty cycle. The network was found to be stable even with node duty cycles as low as 0.19 percent, and able to handle an offered data throughput of 0.5 messages/node/hour. The node duty cycle was shown not to vary significantly with position in the tree network. Packet collisions were rare, validating the medium access function of the SAR protocol.

A proposal of an improved Handoff decision algorithm

A number of variants of traditional Handoff (HO) algorithms have been shown in the literature. In this paper a modified version of HO decision algorithm is proposed. This algorithm has less computational complexity comparing to the traditional HO decision algorithm. This new algorithm measures the distances of adjacent seven cells including the serving cell, instead of scanning the neighboring 16 cells signal strength, so it naturally reduces the searching complexity for handoff by (11/16)%=32%. As a result HO time will be reduced in every case by 32% compared with the traditional handoff algorithm. It also reduces channel usage by not considering more than 50% cells during search, which subsequently increases channel capacity, QoS and reduces delay and call drop.