• Title, Summary, Keyword: CDMA

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Bit Error Probability Analysis of PW/CDMA System in AWGN Noise Environments (펄스폭변조 다중채널 DS/CDMA 시스템의 AWGN 환경하에서의 비트오율 성능 분석)

  • 김명진;오종갑;김성필
    • Proceedings of the Korea Institute of Convergence Signal Processing
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    • pp.9-12
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    • 2001
  • In DS/CDMA system the number of output signal levels increases as multi-channel signals are summed, hence the power amplifier with high linearity is required. PW/CDMA is a transmission technique that performs pulse width modulation on the multilevel signal synthesized from multiple channel data. In PW/CDMA system the signal level is maintained to be binary, hence the modulation and demodulation circuits become simple. In this paper we derive the probability of bit error of the PW/CDMA system in AWGN environment. The results are compared with DS/CDMA system and are verified through the computer simulations.

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Logic gate implementation of constant amplitude coded CS/CDMA transmitter (정포락선 부호화된 CS-CDMA 송신기의 논리 게이트를 이용한 구현)

  • 김성필;류형직;김명진;오종갑
    • Proceedings of the IEEK Conference
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    • pp.281-284
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    • 2003
  • Multi-code CDMA is an appropriate scheme for transmitting high rate data. However, dynamic range of the signal is large, and power amplifier with good linearity is required. Code select CDMA (CS/CDMA) is a variation of multi-code CDMA scheme that ensures constant amplitude transmission. In CS/CDMA input data selects multiple orthogonal codes, and sum of these selected codes are MPSK modulated to convert multi-level symbol into different carrier phases. CS/CDMA system employs level clipping to limit the number of levels at the output symbol to avoid hish density of signal constellation. In our previous work we showed that by encoding input data of CS/CDMA amplitude of the output symbol can be made constant. With this coding scheme, level clipping is not necessary and the output signal can be BPSK modulated for transmission. In this paper we show that the constant amplitude coded(CA-) CS/CDMA transmitter can be implemented using only logic gates, and the hardware complexity is very low. In the proposed transmitter architecture there is no apparent redundant encoder block which plays a major role in the constant amplitude coded CS/CDMA.

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Performance Analysis of FH MC/DS CDMA Stystem with Multi-tone Jamming over Nakakgami Fading Channel (나카가미 페이딩 채널하에서 멀티톤 재밍을 고려한 FH MC/DS CDMA 시스템의 성능분석)

  • Kim, Sang-Wook;Kim, Joon-Bae;Jung, Keun-Yeol;Yang, Jung-Mo;Park, Jin-Soo
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • v.9 no.1
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    • pp.543-546
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    • 2005
  • In this paper, it was estimated the BER performance of the individual system type by applying the SFH type and the FFH type to the FH MC-DS CDMA system that combined the strong points of MC DS/CDMA and that of Frequency Hopping under the Nakagami fading channel with Multi-tone Jamming. An increase in the number of hoppings means that it can improve the BER performance by reducing the receiving burden of the FH MC DS/CDMA by achieving a frequency diversity effect. Therefore, I verified that the performances of the FH MC DS/CDMA system could be improved by increasing the number of hoppings.

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A Study on Dual-rate MC-CDMA Systems (이중전송률 다중반송파 CDMA 시스템)

  • Kim Nam-Sun
    • Journal of the Korea Industrial Information Systems Research
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    • v.10 no.1
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    • pp.1-8
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    • 2005
  • Multicarrier code division multiple access(MC-CDMA) Is a scheme that combines multicarrier modulation with CDMA. It offers robustness to frequency selective fading and can support higher rate data transmission with higher spectral efficiency. The objective of this article to proposed a new asynchronous ME-CDMA system to implement multiple data rate communications. It can be accomplished by changing the number of parallel branch(.p). For the analysis of average BER performance, numerical method and computer simulation were used. After MAI power of received signal calculated, the average BER can be acriuired using Gaussian approximation to MAI. We also compare the system performance with that of a single rate MC-CDMA system.

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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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Effect Investigation of a GP for Asynchronous MC-CDMA Systems (비동기 MC-CDMA 시스템에 대한 보호구간의 영향 분석)

  • Ko, Kyun-Byoung;Hong, Dae-Sik
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.11C
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    • pp.851-859
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    • 2008
  • This paper investigates the effect a guard period (GP) in the form of a cyclic prefix for asynchronous multicarrier-code division multiple access (MC-CDMA) systems. At first, we analyze the performance of asynchronous MC-CDMA systems with a GP, which results in closed-form bit error rate (BER) performance. Furthermore, it confirms that the frequency diversity of MC-CDMA systems is identical to the path diversity. The analytical approach proposed here is extended to the case without a GP. The derived analytical results show that a GP is required for MC-CDMA systems in order to mitigate not only the effect of intersymbol interference (ISI) and intercarrier interference (ICI) but also the desired signal power degradation. In addition, the accuracy of the proposed analysis is verified by simulations.

A Study on the Channel Estimation for MC-CDMA System (MC-CDMA 시스템을 위한 채널 추정에 관한 연구)

  • 박형근;이윤호;김응배;차균현
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.8A
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    • pp.1179-1186
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    • 1999
  • Multi-carrier CDMA technique is more attractive in wireless communication system. It can support the effect of frequency diversity with higher spectral efficiency. In this paper, pilot symbol structure was proposed to estimate chann디 paramenters for MC-CDMA system and we analyzed the perfoemance of proposed MC-CDMA which compensates the received signals using the pilot symbols for link transmission. At first, we proposed the new method of pilot's usage for reverse link transmission that can distinguish accessing users whose signals undergo diggerent channels. And we analyzed the performance of coherent MC-CDMA reception using estimated channel parameters

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Effects of Nonlinearity on the Performance of Multi-Code CDMA Communication Systems (Multi-Code CDMA 시스템에서의 비선형 전력 증폭기의 영향분석)

  • 권진만;김상우
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.6A
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    • pp.855-863
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    • 1999
  • Recently a number of multi-rate CDMA systems have been proposed for the third generation mobile communication system. Multi-Code CDMA (MC-CDMA) offers the system construction advantage of being able to use a single-rate receiver. But MC-CDMA suffers from the distortion due to the nonlinearity of the power amplifier. In this paper, we analyze the effect of the nonlinearity on the bit error rate performance of MC-CDMA systems. A polynomial model is used to represent the amplifier amplitude nonlinearities.

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The Study on Improvement of Traffic Rho Performance in RF Transmitter of CDMA Handset (CDMA 단말기 RF 송신단의 Traffic Rho 성능 개선에 관한 연구)

  • 박희봉;황승훈;황금찬
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.4B
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    • pp.624-628
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    • 2000
  • In this paper, the phenomenon to show in CDMA handset in case of which CDMA handset do not meet Traffic Rho value of IS-98B specifications, which have minimum requirements of CDMA handset about electrical performance is analyzed. This paper proposed method to improve Traffic Rho through improving the matching circuit of TX IF SAW FILTER and deleting noise of LDO(Low Dropout Regulator) to generate 3.OV_TX in TX block. HP8924C(CDMA Mobile Station Tester Set) and HP8595E(Spectrum Analyzer) measures the improved CDMA waveform.

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The Research about Voice Transmission between CDMA Network and PSTN Network Using CDMA Circuit Data Service (CDMA 회선 데이터 서비스를 이용한 CDMA망과 PSTN 망간의 음성 전송에 관한 연구)

  • Park, Yong-Seok;Ahn, Jae-Hwan;Ryou, Jae-Cheol
    • The KIPS Transactions:PartC
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    • v.15C no.5
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    • pp.367-374
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    • 2008
  • To realize the voice privacy between CDMA mobile phone and PSTN terminal, the voice frames shall be transmitted transparently between the heterogeneous networks. For satisfying this requirement, we propose the method which transmits voice frames using the CDMA circuit data channel in real time. In this paper we analyze the causes of voice delay which occurs during voice transmission using circuit data channel. And in order to overcome this kind of delay, the technique controlling the TCP control flag and the variable audio block construction algorithm according to the vocoder output rate are proposed. As a result of experimenting by applying the proposed method, we confirmed that the transit delay was improved with about average 70%.