Browsing by Author "Maruf Hossain, Md."

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Feasibility assessment of implementing GSM or DCS frequency band for 3G wireless network in Bangladesh
(Institute of Appropriate Technology, BUET., 2019-04-24) Maruf Hossain, Md.; Mamun, Dr. Mohammad Arif Hasan
The usages and demand of wireless technologies has been increased incredibly in urban, suburban as well in rural area. To fulfill the user demand and for the self-interest, many service provider companies had been established in Bangladesh with different techniques as, Mobile communication system, WiMAX system and small area Wi-Fi services. Especially mobile wireless communication system has become crowded to fulfill the user demands over the nation. As a result radio frequency plans also getting a challenging factor to cover the whole national area by the updated wireless technologies. To facilitate the users in rural area by the updated 3G and 4G mobile technologies, it is needed to choose an appropriate frequency band to alleviate the existing coverage problem of mobile signals. The aim of this thesis work is to find out a suitable frequency band for 3G mobile communication system in Bangladesh. Three available frequency bands 900 MHz, 1800 MHz and 2100 MHz are selected as the alternatives to complete the analysis of finding suitable target frequency band for 3G system. For this study Analytic Hierarchy Process is applied as a Multi-criteria Decision Making Method (MCDM) which is a technology assessment tool. The assessment has been conducted by considering the quality of signal, operation cost, coverage area, signal penetration, environmental values, economic impacts as criteria and sub-criteria for the target of this thesis work. A number of telecommunication researchers from different universities and professionals of renowned telecommunication industries have been selected and taken their interview to avail expert opinion for the assessment works. Most of those researchers and professionals expressed their opinion as lower band 900 MHz would be a better choice for mobile operators to facilitate more 3G coverage area with less integration and maintenance cost. Based on the thesis result it can be ascertained that lower frequency band 900 MHz can be an appropriate additional choice for high speed 3G mobile communication system in Bangladesh to enhance the coverage area especially in suburban and rural areas. So from the outcomes of this work, mobile operators may be guided to choose an appropriate frequency band for their existing 3G network as lower band spectrum has been proposed to improve the signal penetration as well for more coverage area.
Performance analysis of a subcarrier multiplexed free space optical mimo transmission link through atmospheric turbulence
(Department of Electrical and Electronic Engineering (EEE), 2011-05) Maruf Hossain, Md.; Majumder, Dr. Satya Prasad
Free space optical communications is a line-of-sight (LOS) technology that transmits a modulated beam of visible or infrared light through the atmosphere. Now a days, Free Space Optical (FSO) communication is a very much promising technology for communication. But the main weakness is atmospheric turbulence which causes major transmission impairment for an open air optical communication system. To overcome the effect of atmospheric turbulence, Multiple Input Multiple Output (MIMO) communication system has become a very important topic of research over the past few years, due to its capability to greatly enhance spectral efficiencies. So, free space Multiple Input Multiple Output (MIMO) optical communication system through atmospheric turbulence is studied in this thesis. The main objective of this thesis is to analyze the performance of Free Space optical (FSO) communication through atmospheric channel using QPSK Subcarrier Intensity Modulation. Here the performance analysis for a Subcarrier Multiplexed Intensity modulated OFS link with optical intensity modulation and direct detection considering single transmitter and single photo detector in the presence of atmospheric turbulence is carried out. Then the theoretical analysis is extended to a MIMO optical transmission link in the presence of the atmospheric turbulence effect considering Maximal Ratio Receive Combining (MRRC) technique. The performance of the FSO system is evaluated in the presence of atmospheric turbulence for both SISO and MIMO configurations. In this thesis, the performance results are evaluated and shown in terms of BER for several parameters and it is clearly found that BER performance is significantly improved for a Multiple Input Multiple Output (MIMO) system.