Wyniki wyszukiwania - BazTech

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Cooperative MIMO OFDM system based on Amplify and Forward Relay: Evaluation of ZF-SIC and MMSE-SIC equalization

Rahman M., Alam S., Islam S., Samy A. A., Islam N. A.

Przegląd Elektrotechniczny

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2018

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R. 94, nr 9

75--79

EN

In the world of wireless communication, cooperative communication is a modern and unprecedented approach which enables wireless nodes to transfer the information in a cooperative manner and finally to reach the destination without least possible deterioration. Orthogonal frequency division multiplexing (OFDM) can provide high data rate and better performance and a combination of OFDM and cooperative communication may push a wireless network forward to its next generation with enhanced reliability and efficiency. In this work, we develop a mathematical model for cooperative multiple input multiple output (MIMO) OFDM system. Results are achieved in the study to evaluate and compare bit error rate (BER) for different detection schemes. Based on the results it can be mentioned that the performance of cooperative MIMO-OFDM with space time block code (STBC) under amplify and forward (AF) relay for the MMSE-SIC detection scheme was found very satisfactory with improved signal to noise ratio (SNR).

PL

W artykule przedstawiono model matematyczny kooperacyjnej komunikacji bezprzewodowej wiele wejść, wiele wyjść (MIMO) z multipleksingiem i ortogonalnym podziałem częstotliwości (OFDM). Określono współczynnik BER (bit error rate) dla różnych metod detekcji. Najlepsze parametry otrzymano dla systemu STBC (space time block code).

2

A data mining approach to improve military demand forecasting

Thiagarajan R., Rahman M., Gossink N., Calbert G.

Journal of Artificial Intelligence and Soft Computing Research

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2014

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Vol. 4, No. 3

205--214

EN

Accurately forecasting the demand of critical stocks is a vital step in the planning of a military operation. Demand prediction techniques, particularly autocorrelated models, have been adopted in the military planning process because a large number of stocks in the military inventory do not have consumption and usage rates per platform (e.g., ship). However, if an impending military operation is (significantly) different from prior campaigns then these prediction models may under or over estimate the demand of critical stocks leading to undesired operational impacts. To address this, we propose an approach to improve the accuracy of demand predictions by combining autocorrelated predictions with cross-correlated demands of items having known per-platform usage rates. We adopt a data mining approach using sequence rule mining to automatically determine crosscorrelated demands by assessing frequently co-occurring usage patterns. Our experiments using a military operational planning system indicate a considerable reduction in the prediction errors across several categories of military supplies.

3

Effect of Polymer Cations on Photoluminescence Properties of Blue Emitting Alkaline-Earth Metals and Silicon Based Phosphors

Rahman M., Kida T., Nagano M., Khan M.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 2

249-255

EN

Efficient blue emitting phosphors were prepared by depositing mixed hydroxides of Ca, Sr, Ba, Mg, Eu over spherical SiO2 particles from tetra-ethyl-orthosilicate (TEOS) pre-coated with polycations (polyethyleneimine: PEI) followed by calcination at 1200C in a reducing atmosphere. The prepared phosphor showed intense blue emission, which can be ascribed to 4f 7-4f 65d interconfiguration transitions of Eu2+ ions. In contrast, the luminescence intensity of the phosphor was much decreased when prepared without polycations. It was suggested that negatively charged hydroxides are deposited on positively charged SiO2 surfaces pre-coated with polycations through electrostatic self-assembly interaction. The common formula of the prepared phosphors is AMgSi2O6:Eu2+ (A= Ca, Sr, Ba or fraction of Ca and Sr), where alkaline-earth/Si = 1, the each entire sample was prepared by treating with polycations and without polycations.

4

A new topology-based watermarking method for layered 3D triangular mesh models

Rahman M., Kaneda K., Harada K.

Machine Graphics and Vision

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2005

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Vol. 14, No. 4

427-439

EN

A new topology-based watermarking method is proposed to embed information in objects with layered 3D triangular meshes such as those reconstructed from CT or MRI data. The main idea of the method is to compare the heights of the vertices of a triangle lying in the same layer. A watermark message is converted into a binary bit sequence, and then embedded into the modelin such a way that the first vertex of a triangle in the upper level carries information 1, and the first vertex of a triangle in the lower level carries information 0. For experimental purposes, a watermark message is embedded in a mouse embryo model. It is robust against translation, rotation, re-sectioning, local deformation and scaling. It left some artifacts after re-arrangement of local or global numbering. It is useful for shape sensitive 3D geometric models.