• Title/Summary/Keyword: Bandwidth Efficiency

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A Study on the Enhancement of Isolation of the MIMO Antenna for LTE/DCS1800/USPCS1900 Handset (LTE/DCS1800/USPCS1900 단말기용 MIMO 안테나의 격리도 개선에 관한 연구)

  • Cho, Dong-Ki;Son, Ho-Cheol;Lee, Jin-Woo;Lee, Sang-Woon;Lee, Mun-Soo
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.47 no.10
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    • pp.80-85
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    • 2010
  • In this paper, a MIMO antenna is proposed for LTE/DCSl800/USPCSl900 handset applications. The proposed antenna is based on the IFA and its wide bandwidth is obtained by using a stagger tuning technique. To improve the isolation, a suspended line is connected to the shorting points in two antennas, and capacitors and inductors are added to the connected suspended line. Two identical antennas of which dimension is 2.8cc($40{\times}10{\times}7mm$) are mounted on the two end lines of the system ground plane($40{\times}60mm$). Analysis of the antenna performance and optimization is performed using CST Microwave Studio. The bandwidths are satisfied for LTE band class 13(746-787MHz), class 14(758-798MHz) and DCSl800/USPCSl900 band (1710-1990MHz). The isolations between two antennas are about -12dB for LTE band and -10dB for DCSl800/USPCSl900 band. And the radiation efficiency of each antenna is about for LTE band 33% and 45% for DCSl800/USPCSl900 band respectively.

A Nulling Anti-Jamming Scheme for the Polyphase Filter Bank-Based Satellite Repeat System (다상 필터 뱅크 기반의 위성 중계시스템을 위한 항재밍 기법의 연구)

  • Oh, Jin-O;Im, Sung-Bin;Ko, Hyun-Suk
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.49 no.7
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    • pp.39-47
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    • 2012
  • The combination of the broadband property and the wide area coverage of satellite communications enables high speed transmission. Every user in the region under the satellite beam coverage can tranceiver and one can simultaneously communicate with multiple users. For these reasons, it is one of commendable telecommunication networks for information transfer. Since the satellite communications use open channels, it is likely to cause jamming with unwanted interference signals. In the thesis, APSK (Amplitude Phase Shift Keying) is employed, which is recommended for DVB-S2 due to high-speed transmission and excellent bandwidth efficiency. For obtaining reliable communication under the jamming environments, the communication satellite transponder rests on the polyphase filter bank structure, which enables switching among the subchannels and gain control on each subchannel, resulting in effectively eliminating jamming. Furthermore, the nulling scheme, one of the various anti-jamming approaches, is investigated, in which unwanted jamming signals are eliminated in the frequency domain after passing through the analysis part of the polyphase filter bank. The performance of the nulling scheme is evaluated for tone jamming and partial band jamming in terms of BER and EVM. The simulation results indicate that the nulling scheme improve the BER and EVM performance over the case without any anti-jamming approach.

Design of Compact and Broadband Quasi-Yagi Antenna Using Balance Analysis of the Balun (발룬의 평형도 해석을 이용한 소형화된 광대역 Quasi-Yagi 안테나 설계)

  • Woo, Dong Sik;Kim, In-Bok;Kim, Young-Gon;Kim, Kang Wook
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.24 no.1
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    • pp.27-35
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    • 2013
  • In this paper, a compact, broadband quasi-Yagi antenna utilizing balance analysis of the ultra-wideband microstrip-to-coplanar stripline(MS-to-CPS) balun is proposed. The antenna size was reduced by removing the reflector on bottom layer and ground plane is used as a reflector. A planar balun that transforms from microstrip(MS) to balanced coplanar stripline(CPS) is characterized in the amplitude and phase imbalances at CPS output ports are investigated and discussed. As compared with the conventional balun, the proposed MS-to-CPS balun demonstrated very wideband performance from 7 to over 20 GHz. From the simulation study, amplitude and phase imbalances are within 1 dB and ${\pm}5^{\circ}$, respectively. The implemented antenna provides very wide bandwidth from 6.9 to 15.1 GHz(74.5 %). The gain of the antenna is from 3.7 to 5.5 dBi, the front-to-back ratio is more than 10 dB, and the nominal radiation efficiency is about 94 %.

Parametric Study of Slow Wave Structure for Gain Enhancement and Sidelobe Suppression (이득 증가와 부엽 억제를 위한 저속파 구조의 설계변수에 대한 연구)

  • Park, Se-Been;Kang, Nyoung-Hak;Eom, Soon-Young
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.27 no.12
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    • pp.1059-1068
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    • 2016
  • This paper proposes slow wave structure(SWS) utilized to increase antenna gain of printed dipole antenna(PDA) and to suppress sidelobe level simultaneously, and makes sure of electrical characteristics of the antenna according to parameter variations of components of the slow wave structure. The printed slow wave structure which is composed of a dielectric substrate and a metal rods array is located on excited direction of the PDA, affecting the radiation pattern and its intensity. Parasitic elements of the metal rods are arrayed in narrow consistent gap and have a tendency to gradually decrease in length. In this paper, array interval, element length, and taper angle are selected as the parameter of the parasitic element that effects radiation characteristics. Magnitude and phase distribution of the electrical field are observed and analyzed for each parameter variations. On the basis of these results, while the radiation pattern is analyzed, array methods of parasitic elements of the SWS for high gain characteristics are provided. The proposed antenna is designed to be operated at the Wifi band(5.15~5.85 GHz), and parameters of the parasitic element are optimized to maximize antenna gain and suppress sidelobe. Simulated and measured results of the fabricated antenna show that it has wide bandwidth, high efficiency, high gain, and low sidelobe level.

Multi-Band Antenna Design by Controlling Characteristic of Third Order Mode (고차 모드 주파수 특성 제어 다중 대역 안테나)

  • Yu, Jaekyu;Zhang, Rui;Liu, Yang;Lee, Jaeseok;Kim, Hyung-Hoon;Kim, Hyeongdong
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.23 no.12
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    • pp.1343-1350
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    • 2012
  • This paper presents a new method for designing a dual-band WIFI antenna using the third-order harmonic mode of a monopole antenna whose first-order mode operates at the low frequency band of WIFI. As analysing the current distribution of the third-order mode of this monopole antenna, the strongest point of electric field can be found. Then by attaching a stub at this point, the resonant frequency of the stub radiator can be adjusted from the third-order mode of the monopole antenna into the high frequency band of WIFI and the input impedance at this resonant frequency can be controlled with the width of the branch, without affecting the low frequency band of WIFI (the first-order mode of the monopole antenna). The compact dual-band antenna is designed at the size of an USB(universal serial bus) dongle and the bandwidth covers 600 MHz(2.3~3 GHz) at 2 GHz and 1 GHz(4.9~5.9 GHz) at 5 GHz under -10 dB which is satisfied with WLAN frequency. Efficiency of proposed antenna achieves over 50 % at WLAN frequency.

An Authentication and Handoff Mechanism using AAA and HMIPv6 on NEMO Environment (이동 네트워크(NEMO)에서 HMIPv6를 적용한 AAA 인증 방안 연구)

  • Choi, Kyung;Kim, Mi-Hui;Chae, Ki-Joon
    • The KIPS Transactions:PartC
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    • v.16C no.2
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    • pp.165-182
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    • 2009
  • Mobile IPv6 spends considerable bandwidth considering that its signal volume is proportional to the mobile and also it should be strengthened to support the binding signal volume, the traffic, and effective mobility. So, the study in NEMO(Network Mobility), an extended version of Mobile IPv6, has been conducted. NEMO provides its mobility by putting several mobiles and more than one portable router into one unit called as mobile network. Because nodes access Internet via the portable router at this time, it receives transparency without any additional work and that much reduces binding signal while solving binding storm. By supporting mobility, NEMO is able to have various mobile structures which realize several networks hierarchically and it is necessary to improve its safety and security by authenticating among the upper networks or the lower ones while moving. Also, it is extremely required to begin a study in the device to improve efficiency accompanied with mobility, which is executed by the fast hand-off as well as the safe authentication. For those reasons, this paper not only classifies various NEMO mobile scenarios into 7 ways, but also provides AAA authentication of each scenario, the authentication through the safety authentication and fast handoff authentication using F+HMIPv6 and the way to reduce both signaling volume and packet delays efficiently during the handoff.

File System Support for Multimedia Streaming in Internet Home Appliances (인터넷 홈서버를 위한 스트리밍 전용 파일 시스템)

  • 박진연;송승호;진종현;원유집;박승민;김정기
    • Journal of Broadcast Engineering
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    • v.6 no.3
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    • pp.246-259
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    • 2001
  • Due to recent rapid deployment of Internet streaming service and digital broadcasting service, the issue of how to efficiently support streaming workload in so called "Internet Home Appliance" receives prime interests from industry as well as academia. The underlying dilemma is that it may not be feasible to put cutting edge CPU, boards, disks and other peripherals into that type of device. The primary reason is its cost. Usually, Internet Home Appliances has its dedicated usage, e.g. Internet Radio, and thus it does not require high-end CPU nor high-end Va subsystem. The same reasoning applies to I/O subsystem. In Internet Home Appliances dedicated to handle compressed moving picture, it is not equipped with high end SCSI disk with fast rotational speed. Thus, it is mandatory to devise elaborate software algorithm to exploit the available hardware resources and maximize the efficiency of the system. This paper presents our experiences in the design and implementation of a new multimedia file system which can efficiently deliver the required disk bandwidth for a periodic I/O workload. We have implemented the file system on the Linux operating system, and examined itsperformance under streaming I/O workload. The results of the study show that the proposed file system exhibits superior performance than the Linux Ext2 file system under streaming I/O workload. The result of this work not only contribute to advance the state f art file system technology for multimedia streaming but also put forth the software which is readily available and can be deployed. deployed.

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Quality Metric with Video Characteristics on Scalable Video Coding (영상 특성을 고려한 스케일러블 비디오 기반 품질 메트릭)

  • Yoo, Ha-Na;Kim, Cheon-Seog;Lee, Ho-Jun;Jin, Sung-Ho;Ro, Yong-Man
    • Journal of Broadcast Engineering
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    • v.13 no.2
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    • pp.179-187
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    • 2008
  • In this paper, we proposed the qualify metric based on SVC and the subjective quality. The proposed quality metric is for a general purpose. It means we can use it for any video sequences regardless of its temporal and spatial characteristics. The Quality of Service(QoS) is one of the important issues in heterogeneous environment which has diverse restrictions such as limited network bandwidth and limited display resolution. Scalable Video Coding(SVC) is the efficient video coding skill in heterogeneous environment. Because SVC can be adapted to various quality bitstreams using three scalabilities(spatial, temporal, and SNR) from one bitstream which has full scalability. To maximize the QoS in this environment, we should consider the subjective quality which is the viewer response. And also we should consider temporal and spatial characteristics of video sequence because the subjective quality is affected by temporal and spatial characteristics of video sequence. To verify the efficiency of the proposed method, we perform subjective assessments. The experimental results show that the proposed method has high correlation with subjective quality. The proposed method can be a decision tool of SVC birstream extraction.

Hybrid Buffer Structured Optical Packet Switch with the Limited Numbers of Tunable Wavelength Converters and Internal Wavelengths (제한된 수의 튜닝 가능한 파장변환기와 내부파장을 갖는 하이브리드 버퍼 구조의 광 패킷 스위치)

  • Lim, Huhn-Kuk
    • Journal of Internet Computing and Services
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    • v.10 no.2
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    • pp.171-177
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    • 2009
  • Optical packet switching(OPS) is a strong candidate for the next-generation internet, since it has a fine switching granularity at the packet level for providing flexible bandwidth, and provides seamless integration between WDM layer and IP layer. Optical packet switching have been studied in two categories: OPS in synchronous and OPS in asynchronous networks. In this article we are focused on contention resolution of OPS in asynchronous networks. The hybrid buffer have been addressed, to reduce packet loss further as one of the alternative buffer structures for contention resolution of asynchronous and variable length packets, which consists of the FDL buffer and the electronic buffer. The OPS design issue for the limited number of TWCs and internal wavelengths is important in the aspect of switch cost and resource efficiency. Therefore, an hybrid buffer structured optical packet switch and its scheduling algorithm is presented for considering the limited number of TWCs and internal wavelengths, for contention resolution of asynchronous and variable length packets. The proposed algorithm could lead to the packet loss improvement compared to the legacy LAUC-VF algorithm with only the FDL buffer.

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An Extended Virtual LAM System Deploying Multiple Route Server (다중 라우트 서버를 두는 확장된 가상랜 시스템)

  • Seo, Ju-Yeon;Lee, Mee-Jeong
    • Journal of KIISE:Information Networking
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    • v.29 no.2
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    • pp.117-128
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    • 2002
  • Virtual LAN (VLAN) is an architecture to enable communication between end stations as if they were on the same LAN regardless of their physical locations. VLAN defines a limited broadcast domain to reduce the bandwidth waste. The Newbridge Inc. developed a layer 3 VLAN product called VIVID, which configures a VLAN based on W subnet addresses. In a VIVID system, a single route server is deployed for address resolution, VLAN configuration, and data broadcasting to a VLAN. If the size of the network, over which the VLANS supported by the VIVID system spans, becomes larger, this single route server could become a bottleneck point of the system performance. One possible approach to cope with this problem is to deploy multiple route servers. We propose two architectures, organic and independent, to expand the original VIVID system to deploy multiple route servers. A course of simulations are done to analyze the performance of each architecture that we propose. The simulation results show that the performances of the proposed architectures depend on the lengths of VLAN broadcasting sessions and the number of broadcast data frames generated by a session. It has also been shown that there are tradeoffs between the scalability of the architecture and their efficiency in data transmissions.