• The Journal of the Korea institute of electronic communication sciences
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• v.2 no.4
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• pp.209-214
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• 2007

This paper effectively suppress the mutual interference simbologan has proposed algorithm using a combination of multi-tier peosepteuron the tab so that the weight update can be done more efficiently. Simulation of the convergence characteristics superior to the average square error, that is research.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.1 no.1
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• pp.55-64
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• 1997

Spread Spectrum Communication is a core technique in CDMA system, but the problem for SS Communication schemes is synchronous method. There are DLL, Tau-dither, SO etc, in the synchronous method. But since there are analog operations, the settling is difficult and size is large. In this paper we realized Digital Delay Lock Loop (DDLL) and estimated it's performance through the Power line experiment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.7
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• pp.1411-1418
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• 1997

This paper presents a statistical analysis of the decision throeshold for derect-sequence spread-spectrum (DS-SS) prallel Pseudo-Noise (PN) code acquistion with a reference filter. The probabilities of detection and false alarm are derived, and the mean acquistion time is evaluated as a measure of the system performance in both nonfading and Rician fiding channels. From the statistical sresults, it is shown that in the performance analysis of the parallel acquisition system with reference filtering, the statistical evaluaion of the decision threshold seems more appropriate than the approximation of the decision threshold adopted in the other schemes[2,3].

• ETRI Journal
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• v.18 no.3
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• pp.127-145
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• 1996

A new analytic framework based on a linear algebra approach is proposed for examining the performance of a direct sequence spread spectrum (DS/SS) slotted ALOHA wireless communication network systems with delay capture. The discrete-time Markov chain model has been introduced to account for the effect of randomized time of arrival (TOA) at the central receiver and determine the evolution of the finite population network performance in a single-hop environment. The proposed linear algebra approach applied to the given Markov problem requires only computing the eigenvector ${\prod}$ of the state transition matrix and then normalizing it to have the sum of its entries equal to 1. MATLAB computation results show that systems employing discrete TOA randomization and delay capture significantly improves throughput-delay performance and the employed analysis approach is quite easily and staightforwardly applicable to the current analysis problem.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.3
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• pp.115-120
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• 2005

In this paper, we propose a personal-computer-based wireless data access system, which use DS/SS(Direct Sequence Spread Spectrum) method and the ISM band of 2.44GHz radio frequency. By applying hi-directional transmission between wireless handy terminals and PCs or servers, it can be easily connected with any kinds of database systems such as Oracle, MS-SQL and MS-ACCESS. Therefore, it could be economically adopted as peripheral equipments for ERP or SCM systems.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.539-542
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• 2005

In this paper, we propose a wireless data access system, which used direct sequence spread spectrum method and the ISM band with 900MHz radio frequency. By applying bi-directional transmission between wireless transmitter and receiver, it can be effectively connected with any kinds of RF-ID with 900MHz ISM band. Therefore it could economically be used as peripheral equipments for RF-ID system.

• Annual Conference of KIPS
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• 2004.05a
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• pp.1347-1350
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• 2004

현재 디지털 이동통신에서 사용되고 있는 DS/CDMA 방식은 멀티미디어 통신과 같은 고속 데이터 전송에 적용할 경우 다중경로 페이딩 채널하에서 인접심볼간 간섭 및 다중접속간섭이 심해지는 문제점을 갖고 있다. 본 논문에서는 이러한 점을 보안하기 위하여 Hybrid DS/FH CDMA 방식을 이용한 시스템에 고속전송을 위한 Multi-Code 시스템을 적용하여 Hybrid DS/FH Multi-Code Spread Spectrum System을 제안하였으며, 컴퓨터 시뮬레이션을 통하여 성능을 분석 검증 하였다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.10 s.352
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• pp.46-54
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• 2006

In this paper, we propose a digital transceiver that can overcome the problems which current analog transceivers have. For the proposed transceiver, we assumed a frequency resource that consists of discrete and narrow channels. We also assumed that person-to-group, group-to-group, as well as person-to-person, voice and data communications with moderate security should be devisedand the data rate is 1 Mbps with simultaneous voice and data. Frequency hewing spread spectrum (FH-SS) and differential 8-PSK (D8PSK) were adopted for security reasons and bandwidth constraints, and for the reduction of implementation complexity, respectively. For the carrier and the symbol timing recovery, the structure of the preamble was proposed based on the IEEE 802.11 FHSS frame format to improve detection probability. The computer simulation results and power budget analysis implies that the proposed system can be usedin simple wireless communications in place of such as analog walkie-talkies.

• The Journal of the Acoustical Society of Korea
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• v.15 no.2
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• pp.79-84
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• 1996

In this paper, adaptive correlator model using backpropagation neural network based on complex multilayer perceptron is presented for suppressing interference of narrow-band of direct sequence spread spectrum receiver in CDMA mobile communication systems. Recursive least square backpropagation algorithm with backpropagation error is used for fast convergence and better performance in adaptive correlator scheme. According to signal noise ratio and transmission power ratio, computer simulation results show that bit error ratio of adaptive correlator uswing backpropagation neural network improved than that of adaptive transversal filter of direct sequence spread spectrum considering of co-channel and narrow-band interference. Bit error ratio of adaptive correlator using backpropagation neural network is reduced about $10^{-1}$ than that of adaptive transversal filter where interference versus signal ratio is 5 dB.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.9
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• pp.1884-1891
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• 2012

In this paper, we design the sliding correlator SS transceiver which supports short message service. We also analyze the PN code acquisition circuit that is essential for spread spectrum receiver. Using Maxplus II tool provided by altera Co., Ltd, we have designed PN code generator, and sliding correlator for PN code acquisition. Then, they have been made into FPGA by way of EPM7064SLC44-10 - a chip of Altera Co., Ltd. Additionally, we have designed delay clock circuit which is faster than the clock of Tx PN clock, designed switching circuit to control the clock rate and data demodulation circuit. The performance of the transceiver is evaluated from the experimental results. Especially, the performance of PN code acquisition accomplished by sliding correlator which is very important to evaluate spread spectrum receiver is evaluated with the comparison of the lock states.