• Title/Summary/Keyword: DS-CDMA

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Performance Analysis of MFSK-MDPSK/DS-CDMa System Employing Diversity Techniquies and Error Coding Technique in Nakagami Fading Environment (나카가미 페이딩 환경하에서 다이버시티기법과 에러 정정부호화 기법을 채용한 MFSK-MDPSK/DS-CDMA 시스템의 성능 분석)

  • 양원일;강희조
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.11 no.4
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    • pp.553-564
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    • 2000
  • In this thesis, mobile communication channel with multi-path fading which is major factor of performance degradation of DS-CDMA system has been considered. An MRC diversity and error correcting coding technique have been used to improve performance of MFSK-MDPSK/DS-CDMA system. The MFSK-MDPSK/DS-CDMA system performance has been obtained quantitatively by the numerical analysis. the modulations under consideration are noncoherent M-ary frequency shift keying(MFSK) and an MFSK based joint frequency phase modulation utilizing MFSK/DS-CDMA and MDPSK-DS-CDMA systems the MFSK-MDPSK/DS-CDMA system obtain a better performance . Also, the error performance of MFSK-MDPSK/DS-CDMA system in Nakagami fading environments is improved by increasing the number of diversity branch and coding gain.

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Comparison and Analysis of the MC DS-CDMA/MPSK and DS-CDMA/MPSK Systems in Nakagami Fading (나카가미 감쇄에서 MC DS-CDMA/MPSK와 DS-CDMA/MPSK 시스템 비교 분석)

  • 이정도;강희조
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.10 no.6
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    • pp.951-958
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    • 1999
  • Multicarrier modulation or orthogonal frequency division multiplexing(OFDM) is a promising technique for mobile communications systems, since it has a strong immunity to multipath fading without employing complicated adaptive equalization. In this paper, performance of MC DS-CDMA/MPSK(multi-carrier direct sequence-code division multiple access/mary phase shift keying) and DS-CDMA/MPSK(direct sequence-code division multiple access/mary phase shift keying) with coherent detection for a CDMA system over Nakagami fading channel analysis. For a given bandwidth, it is shown that MC DS-CDMA/MPSK eventually outperforms DS-CDMA MPSK with random sequences.

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Performance Comparison on Non-linear Distortion for MC-CDMA and MC-DS/CDMA System in Mobile Satellite Quasi-synchronous Return Link (이동 위성 준동기 리턴링크에서 MC-CDMA와 MC-DS/CDMA 시스템의 비선형 왜곡에 대한 성능 비교 분석)

  • 안치훈;최영관;이호진;김동구
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.40 no.3
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    • pp.1-9
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    • 2003
  • We analyze the performances of MC-CDMA and MC-DS/CDMA systems on quasi-synchronized mobile satellite return link. Quasi-synchronization is considered that chip offset between user terminals is within a few chips. Since the transmitted signals of MC-CDMA and MC-DS/CDMA systems have non-constant envelop, they are easily distorted by nonlinearity of transmit amplifier. Since the nonlinear amplifier input signal level of MC-CDMA system using Walsh code to employ frequency domain spreading is lower than that of MC-DS/CDMA system, performance of single user in MC-CDMA system is respectively 2.3dB and 1dB better than that of MC-DS/CDMA system when amplifier input backoff is 0dB and 6dB. However, since interference of MC-DS/CDMA is less than that of MC-CDMA with many subcarriers in quasi-synchronization and AWGN channel, MC-DS/CDMA system is much better than MC-CDMA system as the number of users increases.

Throughput Analysis of Multi-Carrier DS-CDMA System in Rayleigh Fading Channels (레일리 페이딩 채널에서 Multi-Carrier DS-CDMA 시스템의 Throughput 해석)

  • 김영철;노재성;강희조;조성준
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.5 no.6
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    • pp.1066-1072
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    • 2001
  • ALOHA Multi-Carrier DS-CDMA systems in the multipath Rayleigh fading channel. The throughput of two systems are compared according to the length of a packet in the fast Rayleigh and the slow Rayleigh multipath fading. As a result, we have known that Multi-Carrier DS-CDMA system has less capacity than wideband DS-CDMA system in the same bandwidth, but throughput of Multi-Carrier DS-CDMA system is higher than that of wideband DS-CDMA system. And in Multi-Carrier DS-CDMA systems, higher throughput can be obtained through shortening the length of packet in the fast Rayleigh fading, and it is efficient to control the length of a packet adequately or increase the system capacity of Multi-Carrier DS-CDMA system in the slow Rayleigh fading.

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Throughput Analysis of Multi-Carrier DS-CDMA System in Rayleigh Fading Channels (레일리 페이딩 채널에서 Multi-Carrier DS-CDMA 시스템의 Throughput 해석)

  • 김영철;노재성;강희조;조성준
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2001.10a
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    • pp.675-679
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    • 2001
  • In this paper, throughput is derived for slotted ALOHA wideband DS-CDMA and slotted ALOHA Multi-Carrier DS-CDMA systems in the multipath Rayleigh fading channel. The throughput of two systems are compared according to the length of a packet in the fast Rayleigh and the slow Rayleigh multipath fading. As a result, we have known that Multi-Carrier DS-CDMA system has less capacity than wideband DS-CDMA system in the same bandwidth, but throughput of Multi-Carrier DS-CDMA system is higher than that of wideband DS-CDMA system. And in Multi-Carrier DS-CDMA systems, higher throughput can be obtained through shortening the length of packet in the fast Rayleigh fading and it is efficient to control the length of a packet adequately or increase the system capacity of Multi-Carrier DS-CDMA system in the slow Rayleigh fading.

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Performance Improvement of MFSK-MDPSK/DS-CDMA System Employing MRC Diversity Techniques and Convolution Coding Techniques in Nakagami Fading Environment (나카가미 페이딩 환경하에서 MRC 다이버시티기법과 컨벌루션 부호화 기법을 채용한 MFSK-MDPSK/DS-CDMA 시스템의 성능 개선)

  • 박형호;김영철;강희조;이권현;조성준
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.8 no.2
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    • pp.173-184
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    • 1997
  • In most DS-CDMA systems, the modulation scheme used is a simple one. In this paper, the error performance of DS-CDMA system employing a MFSK-MDPSK combined moulation techniques in adopting MRC diversity reception and convolution coding technique are evaluated. The obtained result show that the error performance of MFSK-MDPSK/DS-CDMA system in Nakagami fading environments is improved by increasing the number of diversity branch and coding gain. Also the power efficiency and bandwidth efficiency combined system in MFSK/ DS-CDMA, MDPSK/DS-CDMA are better than conventional MFSK-MDPSK/DS-CDMA systems.

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Performance Improvement of Multi-Carrier DS-CDMA System using Hybrid SC/MRC-Lc/L Diversity Received Technique (Multi-Carrier: DS-CDMA 시스템에서의 하이브리드 SC/MRC-Lc/L 다이버시티 수신 기법을 이용한 성능 개선)

  • Kim, Young-Chul
    • Journal of Digital Contents Society
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    • v.7 no.4
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    • pp.279-285
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    • 2006
  • In this paper, we have considered the performance improvement of Multi-Carrier DS-CDMA system using hybrid SC/MRC-Lc/L diversity receiving technique over multipath fading environment and compared with that of a Wideband DS-CDMA system. In the result, the PBI has caused a performance deterioration over partial bandwidth in Multi-Carrier DS-CDMA system. Also, Multi-Carrier DS-CDMA system using Hybrid SC/MRC-Lc/L diversity received can determined the complexity and the performance vs the expenses for the system that select the number of input branches.

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Analysis of CI/DS-CDMA Communication Systems using Interference of Multiple Carriers (다중반송파간섭을 이용한 CI/DS-CDMA 통신시스템 특성분석)

  • 이강봉;이정재
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2001.05a
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    • pp.129-132
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    • 2001
  • In this paper a new multiple access scheme, CI/DS-CDMA rising the interference of multiple carriers, is introduced. In this system the chip is made up of N orthogonal carriers equally spaced in frequency, where N corresponds to the number of chips in DS-CDMA. The characteristics of CI/DS-CDMA systems in a typical frequency selective fading channel environment, are analyzed. And it is shown that the frequency diversity benefits of this system result in significant performance enhancements relative to traditional DS-CDMA with RAKE receivers.

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Performance Analysis of Quasi-synchronous MC-CDMA and MC-DS/CDMA in Mobile Satellite Return Link (이동위성 리턴링크에서 준동기 MC-CDMA와 MC-DS/CDMA 성능 분석)

  • 안치훈;최영관;이호진;김동구
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.40 no.8
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    • pp.307-317
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    • 2003
  • We analyze the performance of MC-CDMA and MC-DS/CDMA system on quasi-synchronized moble satellite return link. Quasi-synchronization is considered that chip offset between terminals is within a few chips. In 10-3 BER, performance of MC-DS/CDMA system with walsh code is 0.3dB better than that of MC-CDMA system when the number of user is 5 from -0.5 $T_{c}$ to 0.5 $T_{c}$ quasi-synchronization of MC-DS/CDMA system and from -5/64 $T_{c}$ $^{MC}$ to 5/64 $T_{c}$ $^{MC}$ quasi-synchronization of MC-CDMA system. MC-DS/CDMA system with walsh code is over 0.2dB better than that of MC-DS/CDMA system with extended m code and gold code. MC-CDMA system with walsh code is over 1.2dB better than that of MC-CDMA system with gold code when the number of user is 5 and lower than from -5/32 $T_{c}$ $^{MC}$ to 5/32 $T_{c}$ $^{MC}$ quasi-synchronization.

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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