• Title, Summary, Keyword: CDMA

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Performance analysis of Variable Rate Multi-carrier CDMA under an underwater acoustic channel (수중 음향 채널에서 가변 전송율 다중 반송파 CDMA의 성능 분석)

  • Kang, Hee-Hoon;Han, Wan-Ok
    • The Journal of the Korea institute of electronic communication sciences
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    • v.7 no.1
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    • pp.33-38
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    • 2012
  • As underwater channel is very complex and time-varying, don't supports good-quality for communication service. In this paper, a multi-carrier CDMA(MC-CDMA) system for the reliability and robust service in the underwater acoustic channel is proposed and analyzed for its performance. Applied variable rate algorithm to the proposed system gets a channel state information from relationship between SINR and user data-rate. Using channel state information make spectrum usage more efficient and overall system performance improved. In this paper, the performance of proposed system analyzed by simulation. And Pseudo-Random spread codes used in the system are discussed.

Performance of Decorrelator for Multirate Multicarrier DS/CDMA System (다중전송률 다중반송파 DS/CDMA 시스템을 위한 비상관기의 성능)

  • Lee, Seok-Hyun;Lee, So-Young;Kim, Jin-Young
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.10 no.6
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    • pp.31-37
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    • 2010
  • In this paper, a performance of a decorrelating detector for a multirate MC(multi-carrier) DS/CDMA system is analyzed and simulated in a frequency selective Rayleigh fading channel. The performance is compared with that of single rate MC-DS/CDMA system in term of bit error probability. Variable Spreading Length (VSL) is employed for MC-DS/CDMA system as multirate transmission scheme. From simulation result, it is shown that Decorrelator for multirate MC-DS/CDMA achieves high BER performance as well as that of single rate case.

A Study on Binary CDMA System Correlator Design for High-Speed Acquisition Processing (고속 동기 처리를 위한 Binary CDMA 시스템 코릴레이터 설계에 관한 연구)

  • Lee, Seon-Keun;Jeong, Woo-Yeol
    • Journal of the Korea Society of Computer and Information
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    • v.12 no.1
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    • pp.155-160
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    • 2007
  • Because output of multi-code CDMA system adapted high speed data transmission becoming multi-level system use linear amplifier in output stage and complex output signal. Therefore, Multi-Code CDMA system has shortcoming of high price, high complexity etc.. Binary CDMA technology that allow fetters in existing CDMA technology to supplement this shortcoming proposed. In binary CDMA system When correlator process high speed data, bottle-neck phenomenon is happened on synchronization acquisition process, it is very important parameter. Because existent correlator must there be advantage that power consumption is small but flow addition of several stages to receive correlation's value, the processing speed has disadvantage because the operation amount is much. Therefore in this paper, proposed correlator has characteristic such as data is able to high speed processing, chip area is independent and power consumption is constant in structure in binary CDMA system.

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A Design of Correlator with the PBS Architecture in Binary CDMA System (Binary CDMA 시스템에서 PBS 구조를 가지는 코릴레이터 설계)

  • Lee, Seon-Keun;Jeong, Woo-Yeol
    • The Journal of the Korea institute of electronic communication sciences
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    • v.3 no.3
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    • pp.177-182
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    • 2008
  • Because output of multi-code CDMA system adapted high speed data transmission becoming multi-level system use linear amplifier in output stage and complex output signal. Therefore, Multi-Code CDMA system has shortcoming of high price, high complexity etc. Binary CDMA technology that allow fetters in existing CDMA technology to supplement this shortcoming proposed. In binary CDMA system When correlator process high speed data, bottle-neck phenomenon is happened on synchronization acquisition process, it is very important parameter. Because existent correlator must there be advantage that power consumption is small but flow addition of several stages to receive correlation's value, the processing speed has disadvantage because the operation amount is much. Therefore in this paper, proposed correlator has characteristic such as data is able to high speed processing, chip area is independent and power consumption is constant in structure in binary CDMA system.

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Performance Analysis of Dualrate Multi-code/ Multi-carrier CDMA System with Interference Canceller (간섭제거기를 갖는 이중전송률 MC/MC-CDMA 시스템의 성능분석)

  • Kim, Nam-Sun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.10 no.4
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    • pp.830-837
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    • 2009
  • In this thesis, Multi-code/Multi-carrier CDMA(MC/MC CDMA) system which is combination of Multi-code CDMA and Multi-carrier CDMA is analyzed. This system is suitable fur multi-rate services that use multi-codes and high data rate transmission that employ multi-carriers. In addition, the MC/MC CDMA system is robust against frequency selective fading, is good for narrowband interference rejection, and has higher spectral efficiency. In this paper, The users are assigned OVSF codes as a spreading code according to their data rates and divides the active users having different representative code split into a number of groups for effective cancellation. At the receiver, The code grouping interference canceller performs cancellation between the groups. The proposed receiver does not require any information about interference users, such as code, data and amplitude, and has relatively low complexity. The results show the large improvement in performance that can be attained by cancellation scheme.

Performance Improvement of Frequence Sharing of DS-CDMA/TDMA System (DS-CDMA/TDMA 주파수 공유 시스템의 성능 개선)

  • 백승선;강희조
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.5 no.4
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    • pp.639-644
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    • 2001
  • Sequence Code Division Multiple Access) and TDMA(Time Division Multiple Access) system. In this system, the narrowband TDMA signals can cause intolerant interferences to CDMA signals. In this paper, DS-CDMA/TDMA frequency sharing system have been analyzed in AWGN(Additive white Gaussian Noise), MAI (Multi Access Interference) and NI(Narrowband Interference) environment. Also, performance improvement has been obtained by adopting an adaptive notch filtering scheme using complex filter bank and CCI canceller.

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Performance Comparison of Binary Chirp DS-CDMA System over Gaussian Channel (가우시안 채널 하에서 Binary Chirp DS-CDMA System의 성능 비교)

  • Lee, Won-Tae;Lee, Jae-Jo;Byun, Woo-Bong;Woo, Dae-Ho;Byun, Youn-Shik
    • Proceedings of the KIEE Conference
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    • pp.2655-2657
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    • 2004
  • 기존의 DS-CDMA 방식은 잡음이 많거나 채널 왜곡이 심한 환경에서는 성능이 급속히 저하하는 현상이 나타난다. 이러한 문제점 해결을 위한 다양한 연구들이 현재 진행되고 있으며, 본 논문에서도 이에 대한 해결방안을 제시한다. Chirp 방식은 레이더와 같은 변복조 방식에 다양하게 사용되고 있으며, 원하는 주파수 대역으로 쉽게 이동할 수 있고. 구현이 용이하다는 장점이 있다. 본 논문에서는 다중 접속이 가능한 DS-CDMA 기술과 chirp 변복조 기술을 결합한 Binary Chirp DS-CDMA(BCDS-CDMA) 방식을 제안한다. 제안한 DS-CDMA 시스템 성능을 평가하기 위하여, 가우시안 환경에서 기존의 DS-CDMA 방식과 비교 실험을 하였으며, 실험 결과 chirp을 이용한 방식이 DS-CDMA 보다 개선된 성능을 지니고 있음을 알 수 있었다.

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Characteristics of the Required Signal Power for Multimedia Traffic in CDMA Systems (CDMA 이동통신시스템에서 멀티미디어 트래픽의 요구 신호 전력 특성)

  • 강창순
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.27 no.6B
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    • pp.593-600
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    • 2002
  • The reverse link signal power required for multimedia traffic in multipath faded single-code (SC-) and multi-code CDMA (MC-CDMA) systems is investigated. The effect of orthogonality loss among multiple spreading code channels is herein characterized by the orthogonality factor. The required signal power in both the CDMA systems is then analyzed in terms of the relative required signal power ratio of data to voice traffic. The effect of varying system parameters including spreading bandwidth, the of orthogonality factor, and the number of spreading codes are examined. Analytical results show that MC-CDMA users transmitting only a single traffic type require significantly more power than SC-CDMA users with only a single traffic type. On the other hand, MC-CDMA users transmitting multimedia traffic require power levels approximately identical to SC-CDMA users with multimedia traffic. The results can be used in the design of radio resource management (e.g., power allocation) scheme for wireless multimedia services.

Research on Wireless Router for Data Relay between Binary CDMA Pico-Cell Networks (Binary CDMA Pico-Cell 네트워크간의 데이터 중계를 위한 무선 라우터에 대한 연구)

  • Park, Jong-Beom
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.10 no.4
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    • pp.116-124
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    • 2011
  • For Binary CDMA network, communication can be accomplished only within a Pico-net on the boundary of management by the master station because it manages network resources of each entity. In this research, we try to overcome these limits and extend the application for Binary CDMA system to broad-band network. We suggest a new Binary CDMA router such that network is devised by cell unit and multiple Pico-net and a unique address is assigned to each Pico-cell to relaying data between Pico-cells.

Performance of cellular CDMA system for voice/data integrated service (음성/데이타 집적서비스를 위한 CDMA 셀룰러 시스템의 성능 연구)

  • 강군화;조동호
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.19 no.9
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    • pp.1748-1758
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    • 1994
  • Recently, the demand of mobile communication is rapidly increasing. Also, not only the voice service but also the nonvoice services such as data, FAX, and image service are required. Therefore, in this paper, the voice/data intergraed service methods that will be utilized as a basic core technology of the PCS systems are proposed and their performances are analyzed and compared by computer simulation. According to the simulation results, it could be seen that the performance of voice/data integrated PR-CDMA method is better than that of voice/data integrated broadband CDMA method using a dedicated terminal or a voice/data integrated terminal. The reason is that the voice/data integrated PR-CDMA method can overcome the weak points of CDMA protocol, such as a limitation of the fixed CDMA logical channel number and a falling-off in channel utilization, by using PRMA protocol as a multiple access method that the terminals to which a CDMA logical channel is assigned compete.

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