• Title, Summary, Keyword: CDMA

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Design of New Multi-Code CDMA System by Using SOC Technique (SOC 기술을 이용한 새로운 Multi-Code CDMA system의 설계)

  • Kong, Hyung-Yun;Woo, Il-Seung
    • Proceedings of the IEEK Conference
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    • pp.17-20
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    • 1999
  • In this Paper, we discuss reducing the number of orthogonal code in Multi-Code CDMA (MC-CDMA) system. MC-CDMA system is highlighted for multi-media communication services, but conventional MC-CDMA(CMC-CDMA) system are needed many more orthogonal codes compared to traditional direct sequence CDMA(DS-CDMA) systems. in this paper, we propose the system which can reduce the number of orthogonal codes using sub-orthogonal code(SOC) technique. We certificate that the performance of the proposed system shows the almost same result under gaussian noise environment as compared to CMC-CDMA system through Monte-Curio computer simulation method.

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Dynamic Transmission Control Design in Buffered MC-CDMA System (버퍼를 가진 다중코드-코드분할다중접속(MC-CDMA) 시스템에서 동적 전송 제어 프로토콜 설계)

  • Kim, Young-Yong
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.39 no.9
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    • pp.20-27
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    • 2002
  • The demand for multimedia transmission in wireless networking is rapidly increasing. Performance evaluation in the CDMA system has been carried out on the voice-oriented system without re-transmission or buffering. We propose a multimedia access protocol with buffering and ARQ which can meet a variety of QoS requirements. We study the effect of buffering in MC-CDMA(Multi-Code CDMA) and design a dynamic rate control algorithms, whose simulation shows the efficiency of MC-CDMA.

Design and Implementation of a Wireless CCTV System based on the Binary-CDMA Technology (Binary CDMA 기반의 무선 CCTV 시스템 설계 및 구현)

  • Choi, Jae-Won
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.16 no.1
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    • pp.72-80
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    • 2012
  • Binary CDMA is a new standard technology for wireless communication developed by our country that makes high speed communications and good quality of services. In this paper we researched the design and implementation methods of a wireless CCTV System based on the Binary-CDMA technology that makes it freely installed in any place without cables and laying works. We implemented the hardware and software for the CCTV system and developed a Prototype Wireless CCTV system based on the Binary-CDMA technology.

Performance Analysis of TD-CDMA Systems with Cell Synchronization Error (기지국간 동기오차를 고려한 TD-CDMA 시스템 성능 분석)

  • 한진규;권동승;이명원;박한규
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.26 no.12B
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    • pp.1648-1655
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    • 2001
  • TD-CDMA is based on a combination of CDMA, TDMA, and TDD technologies, and it is proposed to support TDD mode for IMT-2000 service. To analyze the performance of TD-CDMA, we have to establish a modeling technique that takes into account the interference that can occur in each scheme. There is special interference in TDD mode, e.g. interference from base station to base station and from mobile to mobile. In this paper, we present an interference model for analyzing the performance of TD-CDMA systems and the slot allocation strategies. This model includes the cell synchronization error. As a result, this paper shows that almost equal slot allocation and low cell synchronization error guarantee desirable performance in TD-CDMA.

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Performance Analysis of Dualrate MC-CDMA Systems Using Hybrid Interference Cancellation (하이브리드 간섭제거기법을 적용한 이중전송률 MC-CDMA 시스템의 성능분석)

  • Kim Nam-Sun
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.3C
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    • pp.228-236
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    • 2006
  • A Multicarrier code division multiple access(MC-CDMA) is a scheme that combines multicarrier modulation with CDMA. It offers robustness to frequency selective fading effect and can support higher rate data transmission with higher spectral efficiency. The objective of this article is proposed and analyzed a new asynchronous MC-CDMA system with various kinds of data rates which employs a multiple access interference (MAI) canceller. The proposed multirate MC-CDMA system can be accomplished by changing the number of Parallel branch(P) according to their data rate and hybrid interference canceller(HIC) are used for MAI cancellation. We compare the performance of proposed system in terms of average bit error rate(BER) with that of a single rate MC-CDMA system. The results show the large improvement in performance that can be attained by the cancellation scheme under multipath environments.

A Study on the Performance of MAC Protocols for High-Speed Mobile Data Services (이동 고속데이타 서비스용 MAC계층 프로토콜의 성능연구)

  • 김태규;조동호
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.19 no.9
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    • pp.1730-1738
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    • 1994
  • Broadband code division multiple access(B-CDMA)previously proposed for personal communication services(PCS) is not suitable for high-speed data services with large variations in speed, because it is designed only for low-speed voice calls with small variations in speed. Meanwhile, hybrid intra-cell TDMA/inter-cell CDMA(Hybrid TDMA/CDMA) recently proposed could accomodate high-speed services easily because of its internal use of the TDMA scheme, but there would be much inefficiency in treating variable bit rate services due to the intrinsic properties of TDMA transmission scheme, In this paper, a media access control(MAC) protocol, called Resevation TDMA/CDMA, which uses a reservation scheme similar to the one in the packet reservation multiple access(PRMA) protocol to compensate for these shortcomings is proposed. In addition, the performance of this protocol is analyzed and compared with conventional protocols by computer simulation. According to the simulation results, it has been shown that the proposed Reservation TDMA/CDMA scheme could support various transmission rates of user data traffics easily, and it could utilize the variations of the treansmission rates in each active call more efficiently.

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Study on Acquisition Method for GAS-CP-CDMA (Cyclic-Prefix Code Division Multiple Access using Good-Autocorrelation-Sequence) (GAS-CP-CDMA 동기 포착 방법 연구)

  • Lee, Seong-Min;Kim, Young-Je;Kim, Whan-Woo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.11A
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    • pp.1087-1094
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    • 2008
  • In this paper, we propose the acquisition method of the Cyclic-Prefix CDMA using Good-Autocorrelation-Sequence (GAS-CP-CDMA) system. The sequences for GAS-CP-CDMA are m-sequence and constant amplitude zero autocorrelation code (CAZAC) with good autocorrelation property. The GAS-CP-CDMA system is proposed for interference cancellation in multi-user and -path environment in co-cell. However, the reliable initial acquisition in multi-path fading channel and multi-user system environment is crucial. In this paper, non-coherent power detector and threshold value are used for discriminating signal acquisition. The sequence used for computer simulation is CAZAC. The simulation results show proper threshold value depends on the number of users. Through the computer simulation, we draw setting up method of the optimum threshold value for the GAS-CP-CDMA system.

A performance analysis of the discrete time DS/CDMA system based on the code phase difference (코드 위상차에 따른 이산 시간 CDMA 시스템의 성능 분석)

  • 안병양
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.35S no.5
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    • pp.11-16
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    • 1998
  • DS/CDMA systems for the high speed communication require high code rats. In discrete time CDMA receivers, the performance degradation, caused by the phase difference between transmission code and reference code, increase the sampling frquency of the receiver. This increment of the sampling frequency makes hard to implement high speed CDMA systems. This paper analyzes the SIR(signal to interference Ratio) performance of the discrete time DS/CDMA system, based on the code phase difference. The results of this paper may be useful to study a low-sampling CDMA receiver.

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Performance Analysis of Multicode DS/CDMA-BPSK Signal in Nakagami Fading Channel (Nakagami 페이딩 채널에서 멀티코드 DS/CDMA-BPSK 신호의 성능 분석)

  • 조성언
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.4 no.1
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    • pp.201-209
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    • 2000
  • In this paper, the bit error rate (BER) performance of Multicode DS/CDMA-BPSK communication system is investigated in the presence of multi user interference and Nakagami fading channel environments. The DS/CDMA-BPSK communication system adopts multicode technique to enhance the data transmission rate. Using the calculated BER performance, BER figures of Multicode DS/CDMA-BPSK communication system are shown to discuss the effect of the number of multi user interference, Nakagami fading index, and data transmission rate. From the results, the transmission rate of DS/CDMA-BPSK signal improve by adopting Multicode technique. And we know that the major parameter of BER performance degradation in Multicode DS/CDMA system is the effect of multi user interference than the fading depth.

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Analysis of Erlang Capacity for Multi-FA CDMA Systems Supporting Voice and Data Services (음성 및 데이터 서비스를 지원하는 다중 반송파 코드 분할 다중 접속방식 시스템의 얼랑 용량 분석)

  • 구인수;양정록;김태엽;김기선
    • Proceedings of the IEEK Conference
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    • pp.37-40
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    • 2000
  • As the number of CDMA subscribers increases, CDMA systems utilize more than one CDMA carrier In order to accommodate Increasing capacity requirement. In this paper, we present a new analytical method for evaluating the Erlang capacity of CDMA systems with multiple CDMA carriers. in the case of the algorithm proposed in 〔5〕, the calculation complexity for evaluating the call blocking probability Is increased proportionally to the sixth power of the number of used CDMA carriers when the CDMA system supports voice and data services. Consequently, It is Impractical to calculate Erlang capacity with the algorithm of 〔5〕especially when the number of used CDMA carriers is larger than 3. To resolve this problem, we propose a new analytical method for evaluating the Erlang capacity. The calculation complexity of the proposed method for evaluating call blocking probability is increased just proportionally to the second power of the number of used CDMA carriers when the CDMA systems support voice and data services.

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