• Title/Summary/Keyword: 비동기식통신

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A Study on relative distance estimation for asynchronous FDD using Two-way ToA (비동기식 FDD에서 Two-way ToA를 통한 상대거리 측정에 관한 연구)

  • Song, Young-Hwan;Park, Jae-Soo;Shin, Young-Jun;Yoon, Chang-Bae
    • The Journal of the Korea institute of electronic communication sciences
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    • v.11 no.12
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    • pp.1175-1186
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    • 2016
  • The relative distance estimation technique is important to Location-Based Service(: LBS) in a wireless communication environment. In this paper, we propose a scheme for measuring the relative distance by utilizing a frame structure of a physical layer in asynchronous Frequency Division Duplexing(: FDD) when the Internal and external infrastructure for position measurement cannot be used. The proposed method is suitable for continuous distance measurement. The test results showed that the proposed method has the accuracy of less than 10 meters on average.

Performance Comparison between Uplink Synchronous Transmission Scheme and Interference Cancellation Technique (역방향 동기식 전송방식과 간섭제거방식 성능 비교)

  • 박장원;홍인기;이승룡
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.26 no.5B
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    • pp.615-622
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    • 2001
  • 본 논문에서는 IMT-2000 3GPP 규격 물리 채널에 따른 역방향 동기식 전송방식(USTS: Uplink Synchronous Transmission Scheme)의 성능을 다양한 채널 환경에 대하여 평가하였으며, 그 결과를 간섭제거 기술에 의한 간섭 제거 효과와 비교 평가하였다. 시뮬레이션 결과 간섭제거 기법에서는 초기 결정값의 정확도에 따라 그 성능이 매우 크게 변화하는데 비하여 역방향 동기식 전송 방식은 안정된 성능을 나타내는 것을 확인할 수 있었다. 또한 매우 많은 사용자 환경에서는 역방향 동기식 전송 방식으로 제거되지 않은 간섭 성분들이 축적되어 그 성능이 열화되는 경향이 있는 반면, 간섭제거 기법에서는 초기 결정값의 정확도만 어느 정도 보장된다고 하면 간섭 신호를 효과적으로 제거할 수 있을 것으로 나타났다.

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A Study on Frequency Modulation Method to Reduce Time Interval Error (주파수 변조 기법에 의한 시간격 오차 개선에 대한 연구)

  • Ahn, Tae-Won;Lee, Won-Seok
    • Journal of the Institute of Electronics and Information Engineers
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    • v.53 no.2
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    • pp.141-146
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    • 2016
  • This paper presents a method to improve time interval error for asynchronous communication systems. The proposed method is designed and simulated with multi-phase VCO, interpolator, phase selector, up-down counter, comparator and adder. The simulation results for CAN communication system show that the maximum time interval error can be tightly managed for satisfying the required specification. The proposed frequency modulation method can be properly used for asynchronous communication systems requiring high reliability.

Performance of Capability Aware Spanning Tree Algorithm for Bridged Networks (브리지 망에서 지원능력을 고려한 스패닝 트리 생성 알고리듬의 성능 분석)

  • Koo Do-Jung;Yoon Chong-Ho;Lim Jae-Myung
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.5B
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    • pp.421-429
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    • 2006
  • In this paper, we suggest a new capability aware spanning tree(CAST) algorithm for Ethernet bridged network which consists of both legacy Ethernet bridges and synchronous Ethernet ones. The legacy spanning tree algorithm specified in IEEE 802.1D standard select root bridge and construct tree based on each bridge's identifier without consideration of each bridge's capability. Thus we note that if the legacy STP may assign a synchronous bridge as a root bridge, the bridge may become a bottleneck for asynchronous trafficbecause of bandwidth limitation for asynchronous traffic. In this paper, the CAST algorithm constructsmultiple spanning tree by using of bridge capability and makes different transmission path for each traffics, can removes this kind of defect. From the simulation results, we can see that the proposed CAST algorithm has better end-to-end delay performance than legacy spanning tree algorithm in high traffic load and multiple hops environment.

A Study on Reverse Link Power Ratio and Channel Estimation Length Optimization of Synchronous DS-CDMA System (동기식 DS-CDMA 시스템의 역방향 채널 전력비와 채널 추정 길이의 최적화에 관한 연구)

  • 박진홍;강성진;강병권;김선형
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2000.05a
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    • pp.222-225
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    • 2000
  • In this paper, a synchronous CDMA system accepted for the cdma2000 standard is simulated to propose optimized reverse link power ratio and channel estimation lengths. Differently from IS-95, the pilot channel is used in the proposed system to estimate fading channel, so optimized estimation lengths are needed. Therefore, in this paper we analyze optimized estimation lengths which is needed to decide the power ratio of pilot channel and fundamental channel. From fixed estimation lengths, we calculate FER with various power ratio values.

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Reverse-Link Performance of Synchronous Cellular DS-CDMA Networks in Dispersive Rician Multipath Fading Channels (디스퍼시브 리시안 다중경로 페이딩 채널에서 동기식 셀룰라 DS-CDMA, 네트워크의 역방향링크 성능)

  • Hwang Seung-Hoon;Hanzo Lajos
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.9A
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    • pp.722-728
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    • 2005
  • In this paper, the reverse-link performance of synchronous DS-CDMA cellular networks is investigated in Rician multipath fading environments. The system's performance is evaluated in terms of the achievable average bit error rate BER) and the user capacities of two different network layouts, namely those of a uniform grid of hexagonal multiple cells and a single isolated cell. In the multiple-cell scenario, the impact of the other cells' interference on the attainable capacity of the synchronous DS-CDMA uplink is investigated. Upon comparing both networks to a conventional asynchronous CDMA system, we demonstrate an achievable user capacity gain of $25\%$ to $56\%$ for synchronous uplink transmissions over that of the corresponding asynchronous transmission scenario at BER = $10^{-3}$.

Implementation of Synchronized Stream Cryptosytsem for Secure Communication in Radio Channel (무선 채널에서의 암호 통신을 위한 동기식 스트림 암호시스템 구현)

  • 홍진근;손해성;황찬식;김상훈;윤희철
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.6A
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    • pp.894-904
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    • 1999
  • In this paper, a synchronized stream cryptosystem for secure communication in radio channel is designed and its security level is analyzed. The main parts of the proposed cryptosystem consist of synchronization pattern generator, session key generator, and key stream generator. The system performance is evaluated by analyzing the security level depending on the randomness, period, linear complexity, and correlation immunity. Experimental results with image data signal in the 10-1 and 10-2 channel error environment demonstrate the proper operation of the implemented crypto system.

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