Iterative turbo beamforming for OFDM based hybrid terrestrial-satellite mobile system

In the context of orthogonal frequency division multiplexing (OFDM)-based systems, pilot-based beamforming (BF) exhibits a high degree of sensitivity to the pilot sub-carriers. Increasing the number of reference pilots significantly improves BF performance as well as system performance. However, this increase comes at the cost of data throughput, which inevitably shrinks due to transmission of additional pilots. Hence an approach where reference signals available to the BF process can be increased without transmitting additional pilots can exhibit superior system performance without compromising throughput. Thus, the authors present a novel three-stage iterative turbo beamforming (ITBF) algorithm for an OFDM-based hybrid terrestrial-satellite mobile system, which utilises both pilots and data to perform interference mitigation. Data sub-carriers are utilised as virtual reference signals in the BF process. Results show that when compared to non-iterative conventional BF, the proposed ITBF exhibits bit error rate gain of up to 2.5 dB with only one iteration

Numerical Solution of the Natural Convection Around a Horizontal Cylinder Subjected to Non-uniform Radiative Heat

A two-dimensional steady model of the natural convection around a cylinder is solved numerically using COMSOL Multiphysics software. The cylinder receives non-uniform heat from a radiating panel, which is assumed to be sufficiently far away so that the flow around the panel does not interfere with the cylinder. Changes in temperature and velocity are monitored for varying heating rates and cylinder sizes. A good agreement is found with numerical results in the literature which deal with isothermal and uniform heating scenarios. Variable flow properties and reradiation effects are found to have an appreciable effect on the temperature and flow around the cylinder. Larger cylinders are found to be more likely to support a flame than smaller cylinders when exposed the same heating rate

An evaluation of classroom instruction and assessment practices and their effects on learners' reading performance in selected secondary schools in pakistan: a case study.

Pertamanya, kajian ini bertujuan menyelidik cara pembacaan / bacaan diajar kepada pelajar EFL Gred 10 di beberapa buah sekolah menengah terpilih di Pakistan. Yang keduanya, menyelidik amalan penilaian bacaan yang dipraktikkan oleh guru-guru di sekolah berkenaan untuk menilai. The purpose of this study is firstly to investigate the manner in which reading is taught to Grade 10 EFL learners in selected secondary schools in Pakistan. Secondly, it is to investigate reading assessment practices carried out by secondary school teachers in the selected schools to assess Grade 10 EFL learners‟ reading comprehension

Design of dielectric resonator antenna arrays for wireless applications

This thesis presents design of dielectric resonator antenna array for wireless applications. Three antenna designed are presented in the following sections. The first design is a notched chamfered two element rectangular dielectric resonator antenna (DRA) array for wireless (WLAN and WIMAX) applications. Here the DRA array is excited by conformal patch connected to microstrip line. The shape is notched and chamfered to improve the performance of the antenna. From the Simulation results it can be observed that the proposed antenna covers 2.4, 3.6 and 5 GHz WLAN bands and 3.4 to 3.7 GHz WIMAX bands, achieving an impedance bandwidth from 2.18 to 3.75 GHz and 4.84 to 5.14 GHz. Parametric study is done by varying the shapes of the rectangular DRA arrays (Simple Rectangle, chamfered and chamfered with notched). Another parametric study is carried out by varying the dimension of the ground plane of the final design. The second design is a rectangular shaped two element Dielectric Resonator Antenna (DRA) array for 2.4 GHz WLAN application. Here microstrip feed line in corporate (parallel) arrangement is used for feeding. Simulation result shows that the antenna achieves a bandwidth from 2.1 to 3 GHz, covering the 2.4 GHz WLAN band. Here the parametric study is done by varying the feed line and the ground plane of the antenna. The simulation results as well as the parametric studies are incorporated in this thesis. The third one is the Design of four element rectangular shaped dielectric resonator antenna (RDRA) array for wireless applications. The RDRA array is fed by rectangular conformal patch (RCP) connected to microstrip line. Simulation result shows that the proposed antenna achieves an impedance bandwidth from 4 GHz to 7.1 GHz covering various wireless bands. Parametric studies have been carried out by varying the RCP height and the ground plane of the final design