• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.4 no.3
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• pp.30-36
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• 1993

This paper presents the RAKE receiver over a multipath fading channel. This interference between the propagation paths in a multipath fading causes a serious degradation in the mobile communication environment. In order to derive the path interference and reduce the fading effect, the RAKE receiver is used. As a result, the RAKE receiver gives a better performance than the DS / SS receiver over a multipath fading channel.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.11
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• pp.5394-5409
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• 2019

The paper investigates a novel detector receiver with Kalman channel information estimator and iterative channel response equalization for MIMO (multi-input multi-output) OFDM (orthogonal frequency division multiplexing) communication systems in fast multipath fading environments. The performances of the existing linear equalizers (LE) are not good enough over most fast fading multipath channels. The existing adaptive equalizer with decision feedback structure (ADFE) can improve the performance of LE. But error-propagation effect seriously degrades the system performance of the ADFE, especially when operated in fast multipath fading environments. By considering the Kalman channel impulse response estimation for the fast fading multipath channels based on CE-BEM (complex exponential basis expansion) model, the paper proposes the iterative receiver with soft decision feedback equalization (SDFE) structure in the fast multipath fading environments. The proposed SDFE detector receiver combats the error-propagation effect for fast multipath fading channels and outperform the existing LE and ADFE. We demonstrate several simulations to confirm the ability of the proposed iterative receiver over the existing receivers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.9C
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• pp.589-595
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• 2011

This paper proposes an improved multi-stage timing offset estimation scheme for orthogonal frequency division multiplexing (OFDM) systems in multipath fading channel environment. The conventional multi-stage timing offset estimation scheme is very sensitive to the random multipath components. By exploiting the sample standard deviation of the cross-correlation values, the proposed scheme achieves a robustness to the random multipath components. Simulation results demonstrate that the proposed scheme has a higher correct estimation probability and has a better mean square error (MSE) performance than the conventional scheme in multipath fading channels.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.4
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• pp.47-55
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• 1994

This paper presents the CDMA system using the RAKE receiver over a multipath fading channel and in multi-user environments. The interference between the propagation paths in a multipath fading causes a serious degradation in the mobile communication environment. In order to derive the path inteference and reduce the fading effect, the RAKE receiver is used. In a computer simulation, the path number of a fading channel and the branch number of the RAKE receiver are modified. As a result, the CDMA system using the RAKE receiver gives a better performance than the conventional CDMA system over a multipath fading channel and in multi-user environments.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.3
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• pp.1-9
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• 1996

in this paper, we analyzed CDD-DLL code tracking loop for tracking of direct-sequence spread-spectrum signals in a multipath fading channel. The multipath fading channel is modeled as two-ray rayleigh fading channel which is well applicable in a land mobile communication environments. We use trackin jitter variance and mean-time-to-lose-lick as performance measures. From the numerical resutls, it is shown that the effect of multipath fading decreases as SNR/bit increases. Also it is shown that CDD-DLL provides superior jitter performance compared with noncoherent DLL and jitter performance improvement is more significant for a two-ray rayleigh fading channel than an AWGN channel.

• Journal of Advanced Navigation Technology
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• v.11 no.3
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• pp.266-273
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• 2007

In this paper presents the WCDMA(Wideband Code Division Multiple Access) system using the rake receiver over multipath fading and wireless mobile communication environments. The interference between the propagation paths in a multipath fading causes a serious degradation in the wireless mobile communication environments. In order to derive the path interference and reduce the fading effect the rake receiver is used. As a result, the WCDMA system using the rake receiver gives a better performance than the convention WCDMA system over a multipath fading and wireless mobile communication environments.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.3
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• pp.10-17
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• 1996

The performance of tau-dither loop (TDL) is evaluated for a direct-sequence spread-spectrum system in a multipath fading channel. The multipath fading channel is modeled as a two-ray rayleight fading channel. The code tracking perfomrance of TDL is analyzed in terms of tracking jitter and mean-tiem-to-lose-lick (MTLL). The tracking jitter performance is degraded while MTLL perfomrance is improved with increasing discriminator offset and decreasing power ratio of main to second paths. It is shown that for a large bit SNR, the effect of multipath fading becomes more significant. And it is also shown that tracking jitter and MTLL performance is less sensitive to delay spacing and discriminator offset for a small bit SNR than for a large bit SNR.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.6 no.1
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• pp.66-76
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• 1995

In this paper, the error rate performance of DS/SSMA system in multipath fading channel is calculated by computer simulation. At first, the multipath fading channel is modeled with TDL(Tap Delay Line) model. The characteristics of channels, including multipath fading effects and error pattern, are examined by doppler frequency and signal bandwidth, and time spread variation. Using the multipath fading channel model, the error rateperformance of block code and convolutional code is compared, thus the coding sys- tem is applied to the DS / SSMA system. The BER results of DS / SSMA system show that the proposed receiver gives about 2~3[dB] improve- ment compared with the conventional receiver.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.126-129
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• 1999

In this paper, it is assumed that a mobile radio channel is a Rayleigh distributed multipath fading channel and Erlang capacity and equivalent channel numbers are calculated for the reverse link of a imperfect power controlled DS/CDMA cellular system considering both shadowing and multipath fading. The DS/CDMA blocking probability is calculated based on a new analysis method that considers Erlang capacity and ICF(interference correction factor) using the median value of $E_{b(i)}$/ $I_{o}$ corresponding to each reverse link user. It is showed that the effect of multipath fading must not be ignored in Erlang capacity of the IS-95 DS/CDMA cellular system and the Erlang capacity is decreased according to the increase of the deviation of the imperfect power control, to the decrease of the processing gain, to the increase of the voice activity.y.

• Journal of Digital Contents Society
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• v.1 no.1
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• pp.39-52
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• 2000

In this paper, we derive the BER performance of an asynchronous DS/CDMA system and analyze the improvement of BER performance through turbo coding and RAKE receiver in multipath Rayleigh fading and impulsive noise environments. As a result, impulsive noise affects the performance of the system more than multipath fading in lower $E_b/N_o$ than a certain threshold. However, in higher $E_b/N_o$, multipath fading are more dominant than impulsive noise. It is found that in lower $E_b/N_o$, turbo code improves the performance of the system against impulsive noise, and in higher $E_b/N_o$, RAKE receiver improves the performance of the system against multipath fading. Therefore, great improvement can be obtained by employing turbo code and RAKE receiver in multipath Rayleigh fading and impulsive noise environments.