• Title/Summary/Keyword: 다중반송파

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Performance Analysis of Multi-channel Joint Detection for CDMA in Multi-path Fading Channel (다중경로 페이딩 채널에서의 CDMA 다중채널 결합 검출 방식의 성능 분석)

  • 황용선;이종훈;김동구
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.8A
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    • pp.1099-1106
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    • 1999
  • In this paper, the bit error ratio(BER) performance of multi-carrier CDMA system in multi-user/multi-path environment is analytically derived, and effect of interferences due to multi-user, multi-carrier, multi-path is analyzed. A multi-carrier/multi-user/multi-path joint detection scheme incorporating a decorrelating detector is proposed, and its performance as well as the enhancement of noise due to decorrelating process are analyzed. BER of the proposed joint detection scheme is only slightly degraded compared to the ideal case of single user environment.

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An Efficient Vehicular Ad-hoc Networks and Ranging System Using Spread Spectrum Multi-carrier Modulation Scheme (SS 다중반송파 변조방식을 이용한 효율적인 차량 에드혹 네트워크 거리측정 기법)

  • Kim, Young-An
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.7A
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    • pp.554-561
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    • 2009
  • In this paper, we propose a novel Vehicular Ad-hoc Network(VANET) which includes communication and ranging features, using Spread Spectrum(SS) multi-carrier modulation scheme. In existing methods, a spread spectrum technique was used to communicate with other vehicles and raging was possible by detecting phase difference between transmission/reception of the PN signal. However, the use of high-speed PN signals is mandatory to detect possible errors of phase difference and to increase the analysis capacity. In the proposed system, multi-carrier modulation scheme was used as solution of mentioned problem. The multi-carrier modulation scheme uses smaller PN signal and chip-rate than the single-carrier modulation, so it is possible to send multiple carrier waves using the same frequency range. This technique (multiple carrier waves) allows to have the Equal Gain Combing (EGC) diversity effect, providing better result in phase difference error detection and raging accuracy.

An Orthogonal Multicarrier DS/CDMA System Based on Convolutional Coding (길쌈부호화를 바탕으로 한 직교 다중반송파 직접수열 부호분할 다중접속 시스템)

  • Kim, Yun-Hui;Lee, Ju-Mi;Song, Ik-Ho;Kim, Hong-Gil;Kim, Seok-Chan
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.37 no.4
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    • pp.35-43
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    • 2000
  • In this paper, we propose to transmit convolutionally coded DS waveforms over orthogonally overlapped subchannels. It is shown that the proposed system, the convolutionally coded orthogonal multicarrier DS/CDMA system, significantly outperforms the system using frequency diversity combining. It is also shown that the proposed system has better performance than the convolutionally coded almost non-overlapped multicarrier DS/CDMA system under the condition that the information rate and total available bandwidth are the same.

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A Multicarrier CDMA System for Multipath and Doppler Diversity (다중경로 및 도플러 다이버시티를 위한 멀티캐리어 CDMA 시스템)

  • Park Hyung-Kun
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.42 no.1
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    • pp.29-37
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    • 2005
  • One of the principal disadvantages of multicarrier modulation technique is the sensitivity to the frequency offset introduced by Doppler shift. This frequency offset introduces inter-carrier interference (ICI) among the multiplicity of carriers in the multicarrier modulated signal. However, Doppler spread induced by temporal channel variations can Provide another means for diversity. In this paper, we propose a modified multicarrier code division multiple access (CDMA) system to exploit Doppler diversity as well as multipath diversity. The key work of our framework is a canonical time-frequency-based decomposition of the mobile wireless channel into series of independent fading channel. The decomposition naturally leads to a time-frequency generalization of the Rake receiver that exploits both multipath and Doppler diversity.

Performance Analysis of the Wide-band Radio Transmission System using a Multi-carrier Adaptive Modulation Schemes (다중반송파 적응변조를 이용한 광대역 무선전송시스템의 성능분석)

  • 임승주;강민구;천현수;강창언
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.5 no.4
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    • pp.621-629
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    • 2001
  • In this thesis a wireless data transmission system has been proposed and analysed that uses the multi-carrier technique with the adaptive modulation scheme. In general, the OFDM(Orthogonal Frequency Division Multiplexing) system is assigning a same amount of information to all sub-carriers in a wireless data transmission. In the proposed system, the different amount of information is assigned to each sub-carrier depending on the state of channel and the target probability of error of system. With the proposed scheme, the transmission rate can be maximized with the fixed power and the required power to transmit the information can be minimized with the target probability of error of system.

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Performance Analysis of Multicarrier DS/CDMA System Employing Combined Modulation techniques in a Nakagami Fading Channel (나카가미 페이딩 채널에서 합성변조 기법을 채용한 다중반송파 DS/CDMA 시스템 성능 분석)

  • 양원일;강희조
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.5 no.1
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    • pp.52-60
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    • 2001
  • In this paper proposes a multi-carrier MFSK-DPSK/DS-CDMA combined modulation techniques in Nakagami fading environment. Also, multi-carrier DS-CDMA combined system is a promising technique for mobile communications systems, since it has a strong immunity to multipath fading and increasing bandwidth efficiency. The modulations under consideration are noncoherent M-ary frequency shift keying (MFSK)and an MFSK based joint frequency phase modulation utilizing differential phase shift keying (DPSK). With the result, performance improvement of power efficiency and bandwidth efficiency combined system in multi-carrier MFSK-DPSK/DS-CDMA are better then conventional communication system.

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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.

Analysis of Synchronous Orthogonal Multicarrier DS-CDMA Systems in Dispersive Multipath Fading Channels (디스퍼시브 다중경로 페이딩 채널에서 동기식 직교 다중반송파 DS-CDMA 시스템의 분석)

  • Hwang Seung-Hoon;Hanzo Lajos
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.43 no.4 s.346
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    • pp.39-43
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    • 2006
  • In this contribution, the achievable performance of orthogonal multicarrier DS-CDMA systems employing synchronous uplink transmissions is investigated. The bit error ratio (BER) performance is analyzed under dispersive Rayleigh multipath fading conditions as a function of the number of users.