Thư viện Kĩ thuật Viễn thông

Bài viết trình bày và phân tích kỹ thuật MIMO-OFDM VBLAST(Multiple Input Muliple OutputOrthogonal Frequency Division Multiplexing Vertical Bell Laboratories Layered Space Time) cho phép tăng dung lượng và chất lượng của hệ thống một cách đáng kể.

3p  visatori2711 17-04-2019 0 0   Download

Bài viết trình bày về sự phổ biến quả nhanh chóng của smartphone trong xã hội hiện nay là một điều không khó để nhận ra, nó mang lại những tiện ích hữu dụng cho người sử dụng. Đó là các ứng dụng chạy trên smartphone, hỗ trợ người dùng trên nhiều lĩnh vực.

5p  hanh_tv28 17-04-2019 0 0   Download

Network-on-Chip (NoC) paradigm allows designers to integrate efficiently more intellectual properties (IPs) into a single chip system. However, the power consumption has become one of the most critical issues for designing such large complex systems. Low power design can be achieved by scaling the voltage and frequency of the target components.

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n this paper, we study performances of multi-hop transmission protocols in underlay cognitive radio (CR) networks under impact of transceiver hardware impairment. In the considered protocols, cooperative communication is used to enhance reliability of data transmission at each hop on an established route between a secondary source and a secondary destination.

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This article proposes BDAaaS, a flexibly adaptive cloud-based framework for real-time Big Data analytics. The framework collects and analyzes data for IoT applications reusing existing components such as IoT gateways, Message brokers and Big Data Analytics platforms which are deployed automatically.

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In this paper, a dual-band antenna that works at 1780 MHz and 2610 MHz has been proposed for 4G-LTE handheld devices. The antenna has been designed on FR4 substrate with sizes of 20 mm × 50 mm × 1.2 mm to fit the mobile casing. The simulation and measurement results of both return loss and radiation patterns have also been presented. Very good agreement between simulated ans measured data has been obtained.

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This paper proposes an analytical model which covers full specification of IEEE 802.11e EDCA. To reduce the complexity, the model is simplified by decomposing the problem in two models based on Markov chain that can be easily solved by numerical method. The proposed model is presented in the theoretical aspect as well as numerical results to clarify its accuracy.

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The sentence alignment approach proposed by Moore, 2002 (M-Align) is an effective method which gets a relatively high performance based on combination of length-based and word correspondences. Nevertheless, despite the high precision, M-Align usually gets a low recall especially when dealing with sparse data problem.

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This paper proposes a novel structure of the inverted F antenna based on meandering and folding methods for the monopole antenna placed on FR4 dielectric plate. The proposed antenna has compact size (21 mm × 14 mm × 3.2 mm). Moreover, this antenna still offers enough wide bandwidth (VSWR ≤ 2), which covers 3G bandwidth. Using the simulation program to optimize antenna structure and calculate the antenna parameters in order to verify its applicability for the 3G mobile devices.

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This paper presents the design of a wideband circularly polarized E-shaped patch antenna for 2.4-GHz wireless local area networks (WLAN) applications. The proposed antenna is a modified form of the conventional circularly polarized E-shaped patch antenna.

7p  vixyliton2711 17-04-2019 0 0   Download