• 제목/요약/키워드: Received transmission

검색결과 761건 처리시간 0.029초

Multirate 무선랜 환경에서 Fragment Burst의 전송을 위한 개선된 NAV Update 방법 (The Improved NAV Update method for Transmit of Fragmented Burst in Multirate WLAN environment)

  • 김태환;송경희;박동선
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2003년도 하계종합학술대회 논문집 I
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    • pp.53-56
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    • 2003
  • In order to enhance the system capacity of multi rate IEEE 802.11 WLAN, we propose the transmission rate select method using the control frame in this paper. The transmission rate is selected dynamically based on the RSSI(Received Signal Strength Indicator) of received control frame. And we also propose the Enhanced NAV Update method for Fragmented MPDU burst transmission in multirate WLAN environment. This method can improve the system capacity by support the burst transmission of fragmented MPDU.

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Establishing Best Power Transmission Path using Receiver Based on the Received Signal Strength

  • 엄정숙;손희동;박용완
    • 인터넷정보학회논문지
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    • 제18권6호
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    • pp.15-23
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    • 2017
  • Wireless power transmission (WPT) for wireless charging is currently attracting much attention as a promising approach to miniaturize batteries and increase the maximum total range of an electric vehicle. The main advantage of the laser power beam (LPB) approach is its high power transmission efficiency (PTE) over long distance. In this paper, we present the design of a laser power beam based WPT system, which has a best WPT channel selection technique at the receiver end when multiple power transmitters and single power receiver are operated simultaneously. The transmitters send their transmission channel information via optically modulated laser pulses. The receiver uses the received signal strength indicator and digitized data to choose an optimum power transmission path. We modeled a vertical multi-junction photovoltaic cell array, and conducted an experiment and simulation to test the feasibility of this system. From the experimental result, the standard deviation between the mathematical model and the measured values of normalized energy distribution is 0.0052. The error between the mathematical model and measured values are acceptable, thus the validity of the model is verified.

RF무선충전 시스템 전송효율 개선 및 비교 분석 (Comparative Analysis and Improvement of Transmitting Efficiency in RF Wireless Charging System)

  • 손명식
    • 반도체디스플레이기술학회지
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    • 제20권4호
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    • pp.102-107
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    • 2021
  • In this paper, the measurements of received power was shown and compared in two developed 5.8GHz 25W wireless charging systems. One is the system using commercial transmission antenna, and the other is the system using transmission antenna combined with metamaterial. The system combined with metamaterial shows higher received power due to negative reflective index of metamaterial. In addition, a comparative analysis of the systems shows that the transmission efficiency in the systems can decrease the real gain of transmission antenna due to higher side robe of beam pattern. The side robe beams of transmitting antenna interferes transmitted beam with the reflected beams from the bottom region due to the side robes. The failure problems of the RF wireless charging systems are discussed and proposed in order to charge mobile devices through the RF wireless charging system.

Tank회로를 이용한 배전선신호 결합장치의 특성분석 (Signal Transmission Characteristic of PLC Coupler using Tank Circuit)

  • 김종수;계문호;유동욱;오성철;김종우
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1993년도 하계학술대회 논문집 B
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    • pp.809-811
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    • 1993
  • The load impedance of power lines generally varies with time, areas, and season. Also, the harmonic noises by the power electrical equipments are scattered through the power lines. The received signal level varies with the environment and is not able to detect the PLC(Power Line Carrier) signal. For this reason, it is requried for the signal transmitter to hold the received signal level uniform independently with the variation of the load impedence. In this paper, the power lines are modeled simply and a method keeping the received signal level uniform is suggested through the analysis of the signal transmission characteritics of the PLC coupler using tank circuit.

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CDMA무선채널에서 압축된 정지영상 전송 시스템의 성능 시뮬레이션 (Simulation of Performance in Compressed Still Image Transmission System over Wireless CDMA Channel)

  • 황태욱;김영철;노재성;조성준
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2001년도 하계종합학술대회 논문집(1)
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    • pp.93-96
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    • 2001
  • In this paper, the performance of DS/CDMA-BPSK system for image transmission is simulated by computer, and received image is compared with the origin image. In order to transmit standard image 'Lena', the image is discrete-cosine- transformed and quantized. Then image transmission data is made through assigning 8 bits to the image and high frequency data part of the image is compressed for reducing the size of data. The source-coded image is transmitted and received by the DS/CDMA-BPSK system. The BER, PSNR, and source Quality are changed according to the number of multiple access users, processing gain of the system, and SMR.

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Energy Efficiency Analysis of Cellular Downlink Transmission with Network Coding over Rayleigh Fading Channels

  • Zhu, Jia
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제7권3호
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    • pp.446-458
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    • 2013
  • Recently, energy-efficient cellular transmission has received considerable research attention to improve the energy efficiency of wireless communication. In this paper, we consider a cellular network consisting of one base station (BS) and multiple user terminals and explore the network coding for enhancing the energy efficiency of cellular downlink transmission from BS to users. We propose the network coded cellular transmission scheme and conduct its energy consumption analysis with target outage probability and data rate requirements in Rayleigh fading environments. Then, the energy efficiency in Bits-per-Joule is further defined and analyzed to evaluate the number of bits delivered per Joule of energy cost. Numerical results show that the network coded cellular transmission significantly outperforms the traditional cellular transmission in terms of energy efficiency, implying that given a Joule of energy cost, the network coded cellular transmission scheme can deliver more bits than the traditional cellular transmission.

무선 광 전송용 APD 전력 공급기와 원통형 레이저형상 보정용 마이크로 렌즈 기술 (The Improved Power Supply for APD and Efficiently Designed Cylindric Micro-lens for a Wireless Optical Transmission System)

  • 김만호
    • 대한전기학회논문지:시스템및제어부문D
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    • 제54권11호
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    • pp.654-659
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    • 2005
  • An improved power supply for APD(Avalanche Photo Diode) with a received optical power monitoring circuit allows the received optical power increase temporary without of the degradation of the electrical signal. For the cost reduction and simple fabrication, an improved power supply has been proposed that it was designed for driving a APD as a receiving device of a wireless optical transmission system. It was demonstrated that it was possible to improve a dynamic range by compensating the temperature coefficient of the APD up to 1.0 V/$^{\circ}C$ through the power supply. Also, for an efficient transmission at the receiver end, a simple structure of a single cylindrical micro-lens configuration was used in conjunction with the laser diode to partially compensate a laser beam ellipticity. For this purpose, an astigmatism introduced by the micro-lens is utilized for the additional compensation of the beam ellipticity at the receiver end. In this paper, it is demonstrated that an efficient beam shaping is realized by using the proposed configuration consisting of the single lens attached to the laser diode.

초음파를 이용한 비상방송시스템에 관한 연구 (Study on the Emergency Broadcasting System Using Ultrasonic Waves)

  • 백동현
    • 한국화재소방학회논문지
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    • 제33권6호
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    • pp.186-189
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    • 2019
  • NFSC202에는 화재로 인하여 하나의 층의 확성기 또는 배선이 단락되어도 다른 층의 화재 통보에 지장이 없도록 규정하고 있다. 이를 위해 Analog digital converter (ADC), High pass filter (HPF), Low pass filter (LPF)로 구성된 초음파송수신장치를 제작하였으며 시험을 통해 해당 장치가 증폭기출력, 확성기용량, 음량레벨의 변동에 관계없이 동작함을 확인하였다. 또한 기준주파수 110 kHz(-12 dB)를 송신하는 경우 단락시 -12dB~-18 dB, 정상인 경우-24 dB~-66 dB, 단선시에는 -66 dB을 초과하는 경우와 수신데이터가 없는 경우의 설정된 값을 만족하였다. 따라서 NFSC202 규정에 적정한 시스템임을 확인하였으며 본 시스템을 적용할 경우 점검기준이나 시험기준이 수정 또는 개정되어야 한다.

Contention-based Reservation MAC Protocol for Burst Traffic in Wireless Packet Networks

  • Lim, In-Taek
    • Journal of information and communication convergence engineering
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    • 제5권2호
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    • pp.93-97
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    • 2007
  • In this paper, centralized access control and slot allocation algorithm is proposed for wireless networks. The proposed algorithm is characterized by the contention-based reservation. In order to reduce the collision probability of reservation request, the base station calculates and broadcasts the transmission probability of reservation requests, and the wireless terminal transmits its reservation request with the received transmission probability. The scheduler allocates the uplink data slots based on the successful reservation requests. Simulation results show that the proposed algorithms can provide high channel utilization, and furthermore, maintains constant delay performance in the heavy traffic environment.

디지털 위성방송 시스템의 고속 서비스를 위한 Pulse Shaping Filter 설계 (Design of Pulse Shaping Filter for High-Speed Service in Digital Satellite Broadcasting System)

  • 오재현;이인섭;이완범;강정용;박형근;김환용
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2002년도 하계종합학술대회 논문집(2)
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    • pp.337-340
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    • 2002
  • In data transmission at the digital satellite broadcasting systems, the delay and spread are caused whit receiving original signals from the transmitter in the receiver. So, there are some problems in data fast transmission. Also, transmitted signals ate received in stale of the combination of transmission delay and noise of channel. The affect of channel noise is reduced when increasing transmission power, but as signal interference due to the transmission delay and spread of channel increase in proportion to the transmission power, there is a problem in spite of increasing the transmission power. And there is the problem to add ISI(inter symbol interference) because the property of the channel is limo-varying due to relative moving in the transceiver Therefore, in this paper, a pulse shaping filter for the high-speed service in digital satellite broadcasting systems was designed and reduced the ISI.

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