• Title/Summary/Keyword: MC 기법

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Crest Factors of 16-QAM Modulated Multicode MC-CDMA Signals Employing Complementary Sequences (이진 상보형 수열 쌍을 대역확산 부호로 사용하고 16-QAM 변조 기법을 이용한 MC-CDMA 신호의 전력 포락선 특성 분석)

  • Choi Byoung-Jo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.9C
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    • pp.817-824
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    • 2006
  • The crest factor properties of 16-QAM modulated one- and two-code assisted multi-carrier code-division multiple-access (MC-CDMA) signals employing complementary pair as spreading sequences are characterized. It is shown that a set of relationship between the two 16-QAM symbols entirely characterize the power envelope waveforms of the signals. There exists 60 different sets of relationship, which results in 16 different crest factors as a result of various equivalent transforms on the corresponding message symbols. It is also shown that the individual crest factor corresponding to each message combination is always bounded by 3dB.

Generation Technique of MC/DC Test Cases for Requirement Diagrams (도형 요구사항의 MC/DC 테스트 케이스 생성 기법)

  • Won, Jong-Seob;Choi, Kyung-Hee;Jung, Ki-Hyun
    • Proceedings of the Korea Information Processing Society Conference
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    • 2008.05a
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    • pp.327-330
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    • 2008
  • 본 논문은 도형 요구사항(Requirement Diagram)을 기반으로 MC/DC를 만족하는 테스트 케이스를 생성하는 방법을 기술한다. MC/DC는 테스트 케이스의 여러 커버리지 중 테스트 케이스의 질 측면과 효율성 측면에서 우수하다. 하지만 MC/DC는 구조적 커버리지(Structural Coverage)로써 이를 바로 도형 요구사항에 대해 적용시킬 수 없다. 그러므로 MC/DC를 기반으로 도형 요구사항에 적용하는 방법을 제시한다.

Performance analysis of MC-CDMA Mobile Communication Systems with Smart Antennas (스마트 안테나를 적용한 MC-CDMA 시스템의 성능 분석)

  • 이종길
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.7 no.4
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    • pp.667-672
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    • 2003
  • Smart antennas will be used mon widely for the higher data rate and the larger number of users as the demand of wireless multimedia service is increased. Therefore, the BER performance is analyzed in this paper for DS-CDMA and MC-CDMA systems using smart antennas. A reverse link channel is simulated assuming the frequency selective Rayleigh fading. The simulation results are presented based on the characteristics of DS-CDMA and MC-CDMA systems according to the signal spectrum bandwidth and the method of adaptive beamforming. The BER performances of both systems are improved as the beam width of smart antennas is decreased. Also, it is shown that the performance of MC-CDMA system is much better than that of DS-CDMA system as the number of users is increased.

Performance Analysis of MC-DS/CDMA System with Phase Error and Hybrid SC/MRC-(2/3) Diversity (위상 에러와 하이브리드 SC/MRC-(2/3)기법을 고려한 MC-DS/CDMA 시스템의 성능 분석)

  • Kim Won-Sub;Park Jin-Soo
    • The KIPS Transactions:PartC
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    • v.11C no.6 s.95
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    • pp.835-842
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    • 2004
  • In this paper, we have analyzed the MC-DS/CDMA system with input signal synchronized completely through adjustment of the gain in the PLL loop, by using the hybrid SC/MRC-(2/3) technique, which is said to one of the optimal diversity techniques under the multi-path fading environment, assuming that phase error is defined to the phase difference between the received signal from the multi-path and the reference signal in the PLL of the receiver. Also, assuming that the regarded radio channel model for the mobile communication is subject to the Nakagami-m fading channel, we have developed the expressions and performed the simulation under the consideration of various factor, in the MC/DS-CDMA system with the hybrid SC.MRC-(2/3) diversity method, such as the Nakagami fading index(m), $the\;number\;of\;paths\;(L_p),$ the number of hybrid SC.MRC-(2/3) $diversity\;branches\;(L,\;L_c),$ the number of users (K), the number of subcarriers (U), and the gain in the PLL loop. As a result of the simulation, it has been confirmed that the performance improvement of the system can be achieved by adjusting properly the PLL loop in order for the MC/DS-CDMA system with the hybrid SC/MRC-(2/3) diversity method to receive a fully synchronized signal. And the value of the gain in the PLL loop should exceed 7dB in order for the system to receive the signal with prefect synchronization, even though there might be a slight difference according to the values of the fading index and the spread processing gain of the subcarrier.

Forward Link Performance of CDMA/FDM Systems with Truncated Adaptive Transmission (차단 적응 전송 기법을 쓴 부호분할 다중접속/주파수분할 방식의 내림 연결 성능)

  • Kim, Hong-Jik;Oh, Jong-Ho;Yoon, Seok-Ho;Lee, Ju-Mi;Song, Ick-Ho
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.7C
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    • pp.666-674
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    • 2005
  • A hybrid multicarrier CDMA/FDM system with a truncated adaptive transmission scheme is analyzed in forward link based on the feedback information from the mobile station. In the single cell environment, the prop(mea scheme outperforms the adaptive FH/DS system as well as the MC DS/CDMA system when orthogonal signature sequences are used. In the multiple cell environment also, the proposed scheme has better performance characteristics than the adaptive FH/DS system when orthogonal and random codes are used as spreading sequences.

A Study on the Effective Capacity increasement and Interference reduction technique for MC-CDMA with a Multiple Antenna System (다중 안테나 환경을 고려한 MC-CDMA 시스템에서의 효율적인 전송 용량 증대와 간섭 완화 기법에 관한 연구)

  • Cha, Dong-Ho;Lee, Kyu-Jin;Hwang, Sun-Ha;Lee, Kye-San
    • Journal of Satellite, Information and Communications
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    • v.6 no.2
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    • pp.117-124
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    • 2011
  • In this paper, we present more effective throughput enhancement technique to improve the data rate and reliability by using the multiple antenna technique. The conventional spatial diversity scheme is limited in according with the interference from each antenna channel status, and the orthogonality of spreading codes and subcarriers are destroyed due to the frequency selectivity. Proposed system is considered MC-CDMA system with 4 transmit antennas and 1 receive antenna. Proposed system based on SVD with the MS-RLS MMSE subcarrier combining method in order to achieve better performance with low computational complexity. Via computer simulation, we confirm that the proposed system is able to improve the BER performance by suppressing the interference of other antenna signals.

Complexity reduced partial transmit sequence for PAPR reduction and performance analysis with nonlinear high power amplifier in MC-CDMA (MC-CDMA에서 PAPR 감소를 위한 복잡도가 감소된 부분전송열 기법과 비선형 고출력 증폭기에 의한 성능 분석)

  • 강군석;김수영;오덕길;김재명
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.5A
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    • pp.305-315
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    • 2003
  • MC-CDMA(Multicarrier code division multiple access), which is based on a combination of OFDM(orthogonal frequency division multiplexing) and CDMA(code division multiple access), has gained a lot of interests in wireless multimedia communications, as high speed data transmission is required for mobile services. MC-CDMA has many advantages for broadband high speed data transmission in multipath environment because it can offer both advantages of the CDMA and the OFDM. However, A high PAPR(peak to average power ratio) problem, which is a major drawback of OFDM, is also shown in the MC-CDMA. In this paper, we propose a new phase factor optimization scheme to reduce complexity in PTS(partial transmit sequence) to reduce PAPR. We also analyze the performance of the MC-CDMA with various PTS schemes to investigate the relations between PAPR characteristics and effect of nonlinear distortion of a high power amplifier. Our simulation results reveal that the proposed PTS scheme reduces PAPR about 0.2∼0.5 dB even with 25% reduced- complexity compared to the conventional scheme.

The Performance Improvement Method using Decision Feedback Channel Estimation Scheme in PB/MC-CDMA System (PB/MC-CDMA 시스템에서 결정 귀한 채널 추정 기법을 이용한 성능 향상 방법)

  • Lee, Kyujin;Kim, Guijung
    • Journal of Digital Convergence
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    • v.12 no.12
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    • pp.329-335
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    • 2014
  • In this paper, to improve the performance of PB/MC-CDMA system, we have researched about the decision feedback channel estimation method using the pilot symbol with data symbol. The PB/MC-CDMA system is able to obtain the improved BER by frequency diversity gain and frequency domain equalizer in the frequency selective fading channel. However, when it is not the estimating of channel exactly, it is degrading the performance of BER in the system for occurred the interference among users. To improve the performane system in the multi-user environment the proposed system is using the decision feedback to estimate channel using the channel estimated value of the first stage and second stage. The proposed system is evaluated by computer simulation. The proposed system is not only able to improve the performance of BER by decreasing the interference to each user, but also the proposed system is possible to reduce number of pilot symbol to estimate the channel. Therefore, it confirmed the proposed system improves the performance than the conventional system.

Karyotype Analysis and Physical Mapping of rDNAs Using McFISH in Jeffersonia dubia Benth (깽깽이풀의 핵형분석과 McFISH를 이용한 rDNA의 물리지도 작성)

  • Kim, Soo-Young;Choi, Hae-Woon;Koo, Dal-Hoe;Kim, Chan-Soo;Bang, Jae-Wook
    • Korean Journal of Medicinal Crop Science
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    • v.13 no.1
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    • pp.48-51
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    • 2005
  • Karyotype analysis and chromosomal locailization of 45S and 5S rDNAs using McFISH (multi-color fluorescence in situ hybridization) were carried out in Jeffersonia dubia Benth., which is one of medicinal plants belonging to Berberidaceae. The somatic metaphase chromosome number was 2n=2x=12 and the size of chromosomes ranged $1.95{\sim}3.50\;{\mu}m$. The chromosome complement consisted of two pairs of metacentrics (chromosomes 1 and 3), two pairs of submetacentrics (chromosomes 2 and 4) and two pairs of subtelocentrics (chromosomes 5 and 6). In McFISH, one pair of 45S rDNA site was detected on the centromeric region of chromosome 2 and three pairs of 5S rDNA sites were detected on the short arm of chromosomes 4, 5 and 6, respectively.

Performance Modeling of Resource Reservation Cost in Wireless/Mobile Networks (무선 이동 망 환경에서 자원 예약 비용 성능 모델링)

  • Won, Jeong-Jae;Lee, Hyong-Woo;Cho, Choong-Ho
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.4C
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    • pp.433-441
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    • 2003
  • We propose a new resource reservation scheme called MC-HMRSVP(Mobile clustering based-Hierarchical mobile ReSource reserVation Protcol) that is an extension of HMRSVP[3,4]. MC-HMRSVP always establishes a virtual cluster called Mobile Cluster, which includes its immediately adjacent MA(Mobile Agent) for passive reservation as well as the current MA for active reservation to which MH(Mobile Host) belongs. Our scheme also establishes the MC regardless of intra/inter region movement by GMA(Gateway Mobile Agent) function when a MH moves. To provide a general formulation on analyzing the performance in terms of reservation cost, we also model the resource reservation cost by using a simple recursive equation. Then, we show that our scheme decreases the reservation cost in comparison with the existing HMRSVP extentions.