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RISS 인기검색어
- 검색키워드
- 저자 : Mostafizur Rahaman (검색결과 3 건)
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Selection of the Best Two-Hop AF Wireless Link under Multiple Antenna Schemes over a Fading Channel
Rahaman, Abu Sayed Md. Mostafizur,Islam, Md. Imdadul,Amin, M.R. Korea Information Processing Society 2015 Journal of information processing systems Vol.11 No.1
In evaluating the performance of a dual-hop wireless link, the effects of large and small scale fading has to be considered. To overcome this fading effect, several schemes, such as multiple-input multiple-output (MIMO) with orthogonal space time block codes (OSTBC), different combining schemes at the relay and receiving end, and orthogonal frequency division multiplexing (OFDM) are used in both the transmitting and the relay links. In this paper, we first make compare the performance of a two-hop wireless link under a different combination of space diversity in the first and second hop of the amplify-and-forward (AF) case. Our second task in this paper is to incorporate the weak signal of a direct link and then by applying the channel model of two random variables (one for a direct link and another for a relayed link) we get very impressive result at a low signal-to-noise ratio (SNR) that is comparable with other models at a higher SNR. Our third task is to bring other three schemes under a two-hop wireless link: use of transmit antenna selection (TAS) on both link with weak direct link, distributed Alamouti scheme in two-hop link and single relay antenna with OFDM subcarrier. Finally, all of the schemes mentioned above are compared to select the best possible model. The main finding of the paper is as follows: the use of MIMO on both hops but application TAS on both links with weak direct link and the full rate OFDM with the sub-carrier for an individual link provide a better result as compared to other models.
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Mostafizur Rahaman,Ibnelwaleed Ali Hussein,Ali Aldalbahi,Anwar Parvez,Joao B. P. Soares 한국고분자학회 2018 Macromolecular Research Vol.26 No.4
In this article, metallocene catalyzed polyethylene homopolymer and ethylene 1,7-octadiene copolymers were synthesized and the produced polymers were characterized. The results show that these polymers were high density polyethylene. The effect of comonomer 1,7-octadiene on thermal, mechanical, and rheological properties of the polymers was investigated. The molecular weight, melting temperature (T m), d-spacing, crystallite size, and % crystallinity (% X c) decrease with the increase in comonomer content. Polyethylene homopolymer and copolymer exhibit cold drawing processes. The tensile stress-strain plots show multiple necks. A reduction in tensile modulus, strength, and strain at break is seen for copolymers compared to homopolymer. The effect of comonomer content on dynamic and extensional rheology of the polymers was also studied. In addition, Direct Current conductivity and dielectric property of the polymers were also reported. The results were interpreted in terms of mainly polymer type, molecular weight, and crystallinity.
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Selection of the Best Two-Hop AF Wireless Link under Multiple Antenna Schemes over a Fading Channel
( Abu Sayed Md Mostafizur Rahaman ),( Md Imdadul Islam ),( M R Amin ) 한국정보처리학회 2015 Journal of information processing systems Vol.11 No.1
In evaluating the performance of a dual-hop wireless link, the effects of large and small scale fading has to be considered. To overcome this fading effect, several schemes, such as multiple-input multiple-output (MIMO) with orthogonal space time block codes (OSTBC), different combining schemes at the relay and receiving end, and orthogonal frequency division multiplexing (OFDM) are used in both the transmitting and the relay links. In this paper, we first make compare the performance of a two-hop wireless link under a different combination of space diversity in the first and second hop of the amplify-and-forward (AF) case. Our second task in this paper is to incorporate the weak signal of a direct link and then by applying the channel model of two random variables (one for a direct link and another for a relayed link) we get very impressive result at a low signal-to-noise ratio (SNR) that is comparable with other models at a higher SNR. Our third task is to bring other three schemes under a two-hop wireless link: use of transmit antenna selection (TAS) on both link with weak direct link, distributed Alamouti scheme in two-hop link and single relay antenna with OFDM subcarrier. Finally, all of the schemes mentioned above are compared to select the best possible model. The main finding of the paper is as follows: the use of MIMO on both hops but application TAS on both links with weak direct link and the full rate OFDM with the sub-carrier for an individual link provide a better result as compared to other models.
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