• 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.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.7
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• pp.1033-1043
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• 1999

We consider an improved multicarrier(MC) CDMA system that combines both DS-CDMA with a concatenated orthogonal/PN spreading sequence and MC modulation. This system incorporates the advantages of DS-CDMA with a concatenated sequence to achieve large user capacity and MC modulation technique to combat the effects of a multipath fading channel and intersymbol interference(ISI). Considering voice activity and imperfect sectorization, the system performance is analysed for the maximal ratio combiner(MRC) under a multicell, multiuser, and multipath Rayleigh/Rician fading channels. The performance of the system is improved much more for the single path fading channel compared to the multipath fading channel. Also the system is shown to have the more improved average bit error rate(BER) over the orthogonal MC-CDMA with the conventional PN sequence.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.486-488
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• 2004

Rayleigh signal fading phenomena due to multipath propagation in wireless communication can be simulated using the sum-of-sinusoids channel model. Jakes' fading model is very simple simulator based on the sum-of-sinusoids and has been widely used. However, It has some short-comings. Its time correlation properties based on the simulated waveform do not correspond to the statistical ones. In this paper, the difference between statistical and time properties of Jakes' fading channel model is examined and new simulator is proposed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.3
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• pp.288-295
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• 2013

In this paper, we compare the existing channel estimation technique for 4S (Ship to Ship, Ship to Shore) maritime communications under AWGN channel model, Rician fading channel model, and Rayleigh fading channel model respectively. In general, the received signal is corrupted by multipath and ISI (Inter Symbol Interference). The estimation of a time-varying multipath fading channel is a difficult task for the receiver. Its performance can be improved if an appropriate channel estimation filter is used. The simulation is performed in MATLAB. In this simulation, we use the popular estimation algorithms, LMS (Least Mean Square) and RLS (Recursive Least-Squares) are compared with respect to AWGN, Rician and Rayleigh channels.

• 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.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.233-236
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• 2000

In this paper, we consider a code acquisition of W-CDMA signals over multipath Rayleigh fading channel when double-dwell serial search code acquisition is used for initial synchronization. We derive the detection and false alarm probability, and mean acquisition time mathematically by taking into account of multiple H$_1$ cells and double-dwell serial search. It is noteworthy that the more the number of the post-detection integration, the shorter the mean acquisition time in low SNR.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.05a
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• pp.280-285
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• 1999

In this paper, we have analyzed a performance of fast frequency hopping communication systems when a rayleigh fading caused by envelope variations of a signal received in multipath channel is, but it is not considered that intentional or unintentional jamming can be. The multipath fading channel and rayleigh fading are confirmed by theoretical analysis. In fading or non-fading, the performance of this system is studied. When the path diversity is applied to this system, the performance is shown to be superior to non-diversity systems about 20dB. for modulation methods, BFSK was compared with DPSK.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.3
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• pp.579-586
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• 1999

In this paper, we have analyzed a performance of fast frequency hopping communication systems when a rayleigh fading caused by envelope variations of a signal received in multipath channel is, but it is not considered that intentional or unintentional jamming can be. The multipath fading channel and rayleigh fading are confirmed by theoretical analysis. In fading or non-fading, the performance of this system is studied. When the path diversity is applied to this system, the performance is shown to be superior to non-diversity systems about 20dB. For modulation methods, BFSK was compared with DPSK.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.2
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• pp.360-367
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• 2006

In this paper, we design the complementary code keying (CCK) modulation/demodulation structure that is proposed in the IEEE 820.11b and IEEE 802.11g. And, this paper proposes the CCK Rake receiver to be fitted for the large delay spread case like the inter-vehicle communications. The channel estimation of each path in the multipath Rayleigh fading channel is done using the packet preamble and, the combining of the multipath signals in the coherent CCK Rake receiver is achieved as the symbol level combining type. In this paper, in order to validate the utilization of CCK modem for the inter-vehicle communications of the telematics communications, we suggest the CCK modem performance that is made for the multipath Rayleigh fading channel with the mobile speed of 300km/h.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.397-400
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• 2002

In this paper, a novel noncoherent multiuser detector with diversity reception for a differentially encoded DS/CDMA signal in a frequency-selective Rayleigh fading channel is proposed. The proposed receiver employs multipath decorrelator and decision feedback differential detector (DFDD) with diversity reception. DFDD performs differential encoding and diversity combining. The performance is obtained by analysis and simulation and it is sown that the proposed receiver outperforms conventional differential receiver with slight increase of complexity.