Anis Ahmed

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.

Design and performance analysis of rectangular microstrip patch antenna at 2.45 GHz

This paper presents simulation and performance analysis of a single element rectangular microstrip patch antenna (RMPA) and a 2×1 patch array for Industrial, Scientific and Medical (ISM) band (2.45 GHz). Both the antennas are designed over a Flame Retardant-4 (FR-4) substrate with dielectric constant (ε0) of 3.8, thickness (h) of 1.5 mm and loss tangent of 0.02. The optimum design parameters of the antennas are selected to achieve the compact dimensions, as well as the best possible characteristics such as resonant frequency, high gain, high radiation efficiency etc. Return loss of single element and double element antenna is -38.5 dB and -37.67 dB respectively and gain is 5.49 dB and 8.0 dB respectively. Gain, directivity and bandwidth (BW) enhancement is obtained in two element patch array. Microstrip line feed is used, simulation results are obtained using CST Microwave Studio and the fabricated antennas are measured using Wave and Antenna Training System (WATS-2002).

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.

Measurement of pulse dispersion in optical fiber communication system

Fiber optic communication technologies are constantly growing and facing more challenges that limit its ability to transmit for long distances with great capacity. One of these challenges is the degradation phenomenon that occurs when optical signals pass through the fiber. There are two causes of degradation - power attenuation and dispersion. Minimization of these effects will help the system to support long haul transmission with high capacity. The dispersion effect is studied and analyzed in this paper. The typical dispersion coefficient for Plastic Optical Fiber is 0.3 ns/ nm.m and from practical measurement we have found it to be 22 ns/ nm.m. Simulation is done to show the output response for glass fiber. It is found that for single mode fiber with 1550 nm Laser source and speed of 2.5 Gbps, the system performance is limited to a distance of 15 km and this is due to the high dispersion and attenuation effect.

Analysis of path loss characteristics in Body Area Network for different physical structures

Wireless Body Area Network (WBAN) is one of the latest technologies in wireless communication, and is being widely studied for its applications in military, healthcare, sports, and other sectors. In this paper transmission coefficients S21 are measured for several on-body radio channels and the effects of two different body structures on path loss coefficients are determined. Considering static position of body in the laboratory, measurements are carried out for Line-of-Sight (LOS) and Non-Line-of-Sight (NLOS) radio channels by using two identical tri-slot microstrip patch antennas of 2.48 GHz connected with a vector network analyzer (VNA). Using necessary statistical method path loss coefficients are calculated from the measured data and compared to explore the effect of different types of bodies on WBAN performance. Finally, we have tried to justify the reasons for considering LOS and NLOS measurements separately in establishing an accurate channel model for BAN.

Analysis of nonlinear three-layer optical waveguide

Optical waveguides are characterized by regions of high refractive index bounded by regions of lower index regions and can be categorized as planar, channel, and fiber guides. Monochromatic Laser light is used as the signal carrier through the optical waveguide. If the strength of Laser light is increased, the repeater distance of an optical fiber network can be increased. So to obtain high intensities, it is usually necessary to focus laser beams into the higher index guided region of the optical waveguide where signal processing will take place. However, high laser intensity within a small guided region will cause nonlinear behavior of the waveguide. In this research work the refractive index of the waveguide is assumed to be the function of the square of electric field. Various guided structures are analyzed considering nonlinear refractive index. First the eigenvalue equation is solved to determine the confined guided modes and then the propagation of these modes through different structures are found using Beam Propagation Method (BPM). Since the efficiency of a nonlinear interaction depends at least linearly, and in many cases quadratically, on the interaction distance, clearly there is a trade-off in the efficiency between high intensity and interaction length.

Performance analysis of navigation by the integration of GPS-24 with LEO & GEO

An integrated network consisting of GPS-24 (global positioning system), LEO (Low earth orbit) and GEO (geostationary earth orbit) is analyzed in order to find the position coordinates of a GPS receiver or user position by calculating the position coordinates of GPS satellites. The integrated network is designed to extend the coverage area of GEO satellites up to the polar regions as well as to improve the user position accuracy. Satellite visibility through GPS receiver has been investigated using complex simulations of failure scenarios by giving shadow effect. An algorithm is proposed to estimate the userpsilas position from the known parameters of GPS satellites. Numerical analysis is carried out for the selection of best four satellites to be used for the calculation of userpsilas position. A new approach is also developed for the determination of minimum dilution of precision (DOP) using such integrated network.