• Title, Summary, Keyword: wireless local area network(WLAN)

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Design and Implementation of Dual Band Antenna for IMT-2000 and 5.7㎓ Wireless Local Area Network (IMT-2000/5.7㎓ 무선 LNA용 이중공진 안테나의 설계 및 구현)

  • 김창일;김주성;공성신;양운근
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • pp.237-240
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    • 2002
  • In this paper, we designed and implemented the dual band antenna for IMT-2000 and 5.7㎓ WLAN(Wireless Local Area Network). The antenna was designed by using 3D simulations program, HFSS(High Frequency Structure Simulator). The electrical characteristics were measured by using HP 8720C network analyzer and measured maximum S$\sub$11/ was -25㏈, and maximum VSWR(Voltage Standing Wavc Ratio) was 1.26 for all frequency bands of interests in IMT-2000 and 5.7㎓ WLAN. Simulation results for antenna gain at 2㎓ and 5.7㎓ were 1.31㏈i and 4.1㏈i with omni directional radiation pattern. Implemented antenna is compact sized and can be produced in low cost enough for commercialization.

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The Design of a Network based Visual Agent Platform for Tangible Space (실감 만남을 위한 네트워크 기반 Visual Agent Platform 설계)

  • Kim, Hyun-Ki;Choy, Ick;You, Bum-Jae
    • Proceedings of the KIEE Conference
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    • pp.258-260
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    • 2006
  • In this paper, we designed a embedded system that will perform a primary role of Tangible Space implementation. This hardware includes function of image capture through camera interface, image process and sending off image information by LAN (local area network) or WLAN(wireless local area network). We define this hardware as a network based Visual Agent Platform for Tangible Space

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Viterbi Decoder-Aided Equalization and Sampling Clock Recovery for OFDM WLAN (비터비 복호기를 이용한 OFDM-WLAN의 채널등화 및 샘플링 클럭추적)

  • Kim Hyungwoo;Lim Chaehyun;Han Dongseog
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.42 no.5
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    • pp.13-22
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    • 2005
  • IEEE 802.11a is a standard for the high-speed wireless local area network (WLAN), supporting from 6 up to 54 Mbps in a 5 GHz band. We propose a channel equalization algerian and a sampling clock recovery algorithm by utilizing the Viterbi decoder output of the IEEE 802.11a WLAN standard. The proposed channel equalizer adaptively compensates channel variations. The proposed system uses re-encoded Viterbi decoder outputs as reference symbols for the adaptation of the channel equalizer. It also extracts sampling phase information with the Viterbi decoder outputs for fine adjustment of the sampling clock. The proposed sampling clock recovery and equalizer are more robust to noise and frequency selective fading environments than conventional systems using only four pilot samples.

Study on the Performance of Wireless Local Area Network in a Multistory Environment with 8-PSK TCM

  • Suwattana, Danai;Santiyanon, Jakkapol;Laopetcharat, Thawan;Charoenwattanaporn, Monton;Goenchanart, Ut;Malisuwan, Settapong
    • Proceedings of the IEEK Conference
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    • pp.549-551
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    • 2002
  • A Wireless Local Area Network (WLAN) is a flexible data communication system implemented as an extension to, or as an alternative for, a wired LAN with in a building or campus. However, communications in an indoor environment present problems not encountered in outdoor wireless communication systems. Since cellular type systems are interference limited, the indoor environment is more hostile than the outdoor environment due to the lower propagation constant. In this paper, the equation for the signal to interference ratio in a multistory building will be derived. Knowing the S/I ratio, the floor frequency reuse can be determined. Finally, the simulation in this research is designed to study the performance (BER) of WLAN system in the multistory environment by applying the 8-PSK Trellis Coded modulation technique. The procedure allows a quick evaluation of BER in Wireless LAN system due to the co-channel interference.

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Remote Devices Data Monitoring System based on Wireless PDA (무선 PDA 기반의 원격 장치 데이터 모니터링 시스템)

  • Seo, Jung-Hee;Kim, Kil-Young;Park, Hung-Bog
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.611-614
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    • 2007
  • This paper suggests a TCP/IP-based remote data monitoring system, which combines PDA (Personal Digital Assistant) and WLAN (Wireless Local Area Network) technologies. Wireless PDA devices are used for remote monitoring of wireless communication by continuously collecting remote device data transmitted from servers such as temperature, humidity and device status, and displaying them on mobile devices. Therefore, remote data monitoring systems that integrate wireless and wired services provide data collection adaptive to administrators and efficient identification of device status.

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A Distributed Wireless Local Area Network (WLAN) Access Scheme for Efficient WLAN Communication in Busy Train Stations (혼잡 철도 역사에서 효율적인 무선랜 통신을 위한 무선랜 분산 접속 방법)

  • Koh, Seoung-Chon;Choi, Kyu-Hyoung;Kim, Ronny Yongho
    • Journal of the Korean Society for Railway
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    • v.17 no.6
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    • pp.402-409
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    • 2014
  • Wireless local area network (WLAN) is a widely used wireless access method due to its easy usability and excellent performance. However, its performance degrades significantly as the number of users increases. In busy train stations, where the number of WLAN users are large and, more importantly the number of simultaneous packet transmission attempts is extremely large due to the time synchronization upon train arrival, the packet transmission delay problem is very severe and almost impossible for WLAN stations to initiate communication with WLAN networks. In this paper, a novel distributed WLAN access scheme for efficient WLAN communication in busy train stations is proposed. Using the proposed scheme, WLAN access delay can be significantly reduced under highly congested traffic environments. Therefore, a significant performance enhancement for the WLAN performance used in the Communication Based Train Control (CBTC) can be achieved.

IEEE 802.11 WLAN 환경에서 전력 절감 방식 연구 동향

  • Jin, Seong-Geun
    • Information and Communications Magazine
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    • v.31 no.5
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    • pp.73-79
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    • 2014
  • IEEE 802.11 Wireless Local Area Network (WLAN)을 위한 전력 절약 방식에 관한 연구는 오랫동안 연구 되었음에도 불구하고 계속 발전하고 있다. 본 고는 최근 진행된 IEEE 802.11WLAN을 위한 전력절약방식에 관해 알아보고 향후 진행될 관련 연구 방향에 대해서 논의해 본다.

Heuristic Algorithms for Optimization of Energy Consumption in Wireless Access Networks

  • Lorincz, Josip;Capone, Antonio;Begusic, Dinko
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.5 no.4
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    • pp.626-648
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    • 2011
  • Energy consumption of wireless access networks is in permanent increase, which necessitates development of more energy-efficient network management approaches. Such management schemes must result with adaptation of network energy consumption in accordance with daily variations in user activity. In this paper, we consider possible energy savings of wireless local area networks (WLANs) through development of a few integer linear programming (ILP) models. Effectiveness of ILP models providing energy-efficient management of network resources have been tested on several WLAN instances of different sizes. To cope with the problem of high computational time characteristic for some ILP models, we further develop several heuristic algorithms that are based on greedy methods and local search. Although heuristics obtains somewhat higher results of energy consumption in comparison with the ones of corresponding ILP models, heuristic algorithms ensures minimization of network energy consumption in an amount of time that is acceptable for practical implementations. This confirms that network management algorithms will play a significant role in practical realization of future energy-efficient network management systems.

Design and Implementation of 2.4/5 GHz Dual-Band Plate Type Antenna for Access Point of Wireless LAN (2.4/5 GHz 무선 LAN 액세스 포민트용 이중 공진 판형 안테나 설계 및 구현)

  • Lee Won-Kew;Son Ji-Myoung;Han Jun-Hee;Yang Woon-Geun
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.17 no.5
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    • pp.401-407
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    • 2006
  • In this paper, we present a small-sized and light weighted dual-band antenna for an access point of 2.4/5 GHz dual-band WLAN(Wireless Local Area Network). The antenna for WLAN should show the characteristic of omni-directional radiation pattern. First, to obtain the omni-directional radiation pattern the proposed dual-band antenna has an orthogonal inverted triangular type element at the center and locates four resonating elements symmetrically around it. Also, for the purpose of easy manufacturing and miniaturization of the antenna, we changed the central element which had the orthogonal inverted triangular type structure into the plate type. Measured $S_{11}$ for the proposed dual-band plate type antenna showed characteristic which was less then -12.8 dB for WLAN frequency bands. Measured results for the maximum gain showed 3.17 dBi at 2.44 GHz, 5.38 dBi at 5.77 GHz with omni-directional radiation pattern. The implemented antennas showed applicable performances for the access point of WLAN.

Lower Characteristic Impedance Based Compact f λ0/4 Short-Circuited Stub UWB Bandpass Filter with WLAN Stopband (저특성 임피던스의 λ0/4 단락 스터브 기술을 이용한 WLAN 저지 대역을 가지는 UWB BPF)

  • Hoa, Duong Thai;Joo, Hyo-Suk;Kim, Ihn-Seok
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.20 no.4
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    • pp.323-332
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    • 2009
  • In this paper, we introduce a modified short-circuited stub bandpass filter suitable for ultra-wideband(UWB) applications utilizing low temperature co-fired ceramic(LTCC) technology. By modifying the conventional short-circuited stub bandpass filter structure with stubs and connecting lines of lower characteristic impedances, the number of stubs has been reduced from 5 to 2 on a high dielectric constant substrate($\varepsilon_r$ = 40). A wireless local area network (WLAN) stopband in the frequency range of 5.15 to 5.825 GHz has been inserted into the filter characteristic using three short-circuited coupled lines. The filter has been measured with an insertion loss less than 1.0 dB and return loss better than 10 dB in the pass bands. A bandwidth ratio of 109.49 % has been achieved. Measurement results agree well with simulation results. The dimensions of the filter are $4{\times}8{\times}0.57\;mm^3$.