• Title/Summary/Keyword: Distributed antenna system

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Frequency Spectrum Analysis of Electromagnetic Waves Radiated by Electric Discharges

  • Park, Dae-Won;Kil, Gyung-Suk;Cheon, Sang-Gyu;Kim, Sun-Jae;Cha, Hyeon-Kyu
    • Journal of Electrical Engineering and Technology
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    • v.7 no.3
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    • pp.389-395
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    • 2012
  • In this paper, we analyzed the frequency spectrum of the electromagnetic waves radiated by an electric discharge as a basic study to develop an on-line diagnostic technique for power equipment installed inside closed-switchboards. In order to simulate local and series arc discharges caused by an electric field concentration and poor connections, three types of electrode systems were fabricated, consisting of needle and plane electrodes and an arc generator meeting the specifications of UL 1699. The experiment was carried out in an electromagnetic anechoic chamber, and the measurement system consisted of a PD free transformer, a loop antenna with a frequency bandwidth of 150 kHz-30 MHz, an ultra log periodic antenna with a frequency bandwidth of 30 MHz-2 GHz, and an EMI test receiver with a frequency bandwidth of 3 Hz-3 GHz. According to the experimental results, the frequency spectra of the electrical discharges were widely distributed across a range of 150 kHz-400 MHz, depending on the defects, while commonly found between 150 kHz and 10 MHz. Therefore, considering the ambient noise and antenna characteristics, the best frequency bandwidth for a measurement system to monitor abnormal conditions by detecting electromagnetic waves in closedswitchboards is 150 kHz-10 MHz.

Adaptive Radiation in the Cavity using Slot Antenna (캐비티내 슬룻안테나를 이용한 적응분사)

  • Kim, T.B.;Kim, S.G.;Park, Y.S.
    • Proceedings of the KIEE Conference
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    • 1997.07e
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    • pp.1896-1899
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    • 1997
  • In this paper, New radiation system is presented to improve efficiency and distribution of MWO. And it has one input for two excitatied lines with located on them radiation elements(slots). Radiation elements are distributed along the lines the way that the same electrical distances from the magnetron. New radiation system recompences change of impedance at wide b and frequency.

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Design and Implementation of Robustness Distributed RTLS in Dense Environment (밀집 환경에 적합한 신뢰성 있는 분산형 RTLS 시스템의 설계 및 구현)

  • Jang, Hyun-Sung;Choi, Hoon;Jung, Yeon-Su;Baek, Yun-Ju
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.2B
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    • pp.287-295
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    • 2010
  • RTLS used to track the location of object or person in real time. However, if there are a lot of tags and readers, the conventional single RTLS server may fail to estimate location of tags. And if the server cannot receive the tags signal due to pass-loss or NLOS from more than three readers, the server fail to estimate location of tags. In this paper, we propose a special reader which embeds RTLS location engine for distributed RTLS. And by using multi-directional antenna, alleviating multi-path effect and allowing estimate tag's location only using two readers. We also implement the system, we can reduce server packet 16times and get the all results of location estimate in single second. We achieved the location error within 1m.

A Study on 2 X 2 MIMO Propagation Channel Characteristics for Receiving Antenna Spacings (수신 안테나 이격거리에 대한 2 X 2 MIMO 전파 채널 특성에 관한 연구)

  • Park, Se-Hyun;Yoon, Byung-Tae
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.10 no.4
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    • pp.747-752
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    • 2009
  • In this paper, the MIMO(Multi-Input Multi-Output) channel characteristics for Rx antenna spacing are described in the real environment, which has LOS(Ling of Sight) and NLOS (Won-Line of Sight). We developed $2\times2$ MIMO channel measurement system at 2.3GHz Wibro Band. MIMO antenna evaluation parameters such as received power, channel capacity and spatial correlation are evaluated for standard dipole antenna with 0.25, 0.5, 0.75 and 1.0 wavelength spacing at 2-position for LOS and 4-position for NLOS. The spatial correlation is distributed more than 0.9 in most LOS case which might be intricate to operate MIMO communication. MIMO antenna design need to be focused on getting spatial diversity and reducing spatial correlation in LOS case.

Wireless Access Network Virtualization Based on Distributed Antenna Systems (분산 안테나 시스템에 기반한 무선 액세스망 가상화)

  • Kim, Su Min;Jung, Bang Chul
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.16 no.10
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    • pp.2085-2094
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    • 2012
  • In this paper, we propose a wireless access network virtualization algorithm based on a digital unit (DU)-radio unit (RU) separated network structure in a cellular network with multiple radio access technologies (RATs). The proposed wireless access network virtualization algorithm consists of a baseline access network virtualization, RAT virtualization, and access path migration algorithms. Final wireless access network virtualization is performed by sequentially performing these procedures. Through system-level simulations which assume 3GPP LTE and WiMAX systems, the performance of the proposed wireless access network virtualization is evaluated in terms of system throughput for two scenarios according to asymmetry of network traffic load. Numerical results show that our proposed wireless access network virtualization algorithm achieves significant system throughput gain even in asymmetric traffic load and user distribution situations.

Generalized Distributed Multiple Turbo Coded Cooperative Differential Spatial Modulation

  • Jiangli Zeng;Sanya Liu;Hui Wang
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.17 no.3
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    • pp.999-1021
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    • 2023
  • Differential spatial modulation uses the antenna index to transmit information, which improves the spectral efficiency, and completely bypasses any channel side information in the recommended setting. A generalized distributed multiple turbo coded-cooperative differential spatial modulation based on distributed multiple turbo code is put forward and its performances in Rayleigh fading channels is analyzed. The generalized distributed multiple turbo coded-cooperative differential spatial modulation scheme is a coded-cooperation communication scheme, in which we proposed a new joint parallel iterative decoding method. Moreover, the code matched interleaver is considered to be the best choice for the generalized multiple turbo coded-cooperative differential spatial modulation schemes, which is the key factor of turbo code. Monte Carlo simulated results show that the proposed cooperative differential spatial modulation scheme is better than the corresponding non-cooperative scheme over Rayleigh fading channels in multiple input and output communication system under the same conditions. In addition, the simulation results show that the code matched interleaver scheme gets a better diversity gain as compared to the random interleaver.

Performance Modeling of STTC-based Dual Virtual Cell System under the Overlay Convergent Networks of Cognitive Networking (중첩 융합 네트워크 환경을 고려한 STTC기반 이중 셀 시스템 분석 모델)

  • Choi, YuMi;Kim, Jeong-Ho
    • Journal of the Institute of Electronics and Information Engineers
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    • v.49 no.12
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    • pp.20-26
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    • 2012
  • The newly introduced model of a STTC-based Distributed Wireless Communication System (DWCS) can provide the capability of joint control of the signals at multiple cells. This paper has considered the virtual cell systems: the Dual Virtual Cell (DVC), and also proposes DVC employment strategy based on DWCS network. The considered system constructs DVC by using antenna selection method. Also, for multi-user high-rate data transmission, the proposed system introduces multiple antenna technology to get a spatial and temporal diversity gain and exploits space-time trellis codes known as STTC to increase a spectral efficiency.

A Study on the Mobile Communication System for the Ultra High Speed Communication Network (초고속 정보통신망을 위한 이동수신 시스템에 관한 연구)

  • Kim, Kab-Ki;Moon, Myung-Ho;Shin, Dong-Hun;Lee, Jong-Arc
    • Journal of IKEEE
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    • v.2 no.1 s.2
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    • pp.1-14
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    • 1998
  • In this paper, Antenna, LNA, Mixer, VCO, and Modulation/Demodulation in Baseband processor which are the RF main components in Wireless LAN system for ultra high-speed communications network are studied. Antenna bandwidth and selective fading due to multipath can be major obstacles in high speed digital communications. To solve this problem, wide band MSA which has loop-structure magnetic antenna characteristics is designed. Distributed mixer using dual-gate GaAs MESFET can achieve over 10dB LO/RF isolation without hybrid, and minimize circuit size. As linear mixing signal is produced, distortions can be decreased at baseband signals. Conversion gain is achieved by mixing and amplification simultaneously. Mixer is designed to have wide band characteristics using distributed amplifier. In VCO design, Oscillator design method by large signal analysis is used to produce stable signal. Modulation/Demodulation system in baseband processor, DS/SS technique which is robust against noise and interference is used to eliminate the effect of multipath propagation. DQPSK modulation technique with M-sequences for wideband PN spreading signals is adopted because of BER characteristic and high speed digital signal transmission.

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Cooperative Synchronization and Channel Estimation in Wireless Sensor Networks

  • Oh Mi-Kyung;Ma Xiaoli;Giannakis Georgios B;Park Dong-Jo
    • Journal of Communications and Networks
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    • v.7 no.3
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    • pp.284-293
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    • 2005
  • A critical issue in applications involving networks of wireless sensors is their ability to synchronize, and mitigate the fading propagation channel effects. Especially when distributed 'slave' sensors (nodes) reach-back to communicate with the 'master' sensor (gateway), low power cooperative schemes are well motivated. Viewing each node as an antenna element in a multi-input multi-output (MIMO) multi-antenna system, we design pilot patterns to estimate the multiple carrier frequency offsets (CFO), and the multiple channels corresponding to each node-gateway link. Our novel pilot scheme consists of non-zero pilot symbols along with zeros, which separate nodes in a time division multiple access (TDMA) fashion, and lead to low complexity schemes because CFO and channel estimators per node are decoupled. The resulting training algorithm is not only suitable for wireless sensor networks, but also for synchronization and channel estimation of single- and multi-carrier MIMO systems. We investigate the performance of our estimators analytically, and with simulations.

Effects of Array Weight Errors on Parallel Interferene Cancellation Receiver in Uplink Synchronous and Asynchronous DS-CDMA Systems

  • Kim, Yong-Seok;Hwang, Seung-Hoon;Whang, Keum-Chan
    • ETRI Journal
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    • v.26 no.5
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    • pp.413-422
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    • 2004
  • This paper investigates the impacts of array weight errors (AWE) in an antenna array (AA) on a parallel interference cancellation (PIC) receiver in uplink synchronous and asynchronous direct sequence code division multiple access (DS-CDMA) systems. The performance degradation due to an AWE, which is approximated by a Gaussian distributed random variable, is estimated as a function of the variance of the AWE. Theoretical analysis, confirmed by simulation, demonstrates the tradeoffs encountered between system parameters such as the number of antennas and the variance of the AWE in terms of the achievable average bit error rate and the user capacity. Numerical results show that the performance of the PIC with the AA in the DS-CDMA uplink is sensitive to the AWE. However, either a larger number of antennas or uplink synchronous transmissions have the potential of reducing the overall sensitivity, and thus improving its performance.

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