• Information and Communications Magazine
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• v.20 no.5
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• pp.657-667
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• 2003

• Review of Korean Society for Internet Information
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• v.5 no.3
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• pp.84-100
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• 2004

• IT SoC Magazine
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• s.15
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• pp.44-50
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• 2006

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.10
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• pp.1-10
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• 1998

It is important to know phase offsets of a spreading code in the code division multiple access(CDMA) mobile communication systems because different phase offsets of the same spreading code are used to distinguish each base station. When the period of the code is not that long, the relative phase offset between the code and its shifted code can be found by comparing them, but as the period of the code increases it becomes difficult to find the phase offset. This paper describes a method to calculate the phase offset of a binary code based on the number theoretical approach. We define an accumulator function which plays a central role in this paper, and relationships between the functions are clarified. This number theoretical approach and their results show that this method is very easy for the phase offset calculation. Its application to the CDMA system and circuit realization of the phase offset calculation are also discussed.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.11-14
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• 1998

This paper introuces a new efficient method of synchronization acquisition which is the most important element in DS-CDMA system using the phase offset of binary code. This approach uses the binary code function which can easily estimate the phase offset from the received spreading waveforms which respect to the receiver-stored replica of the spreading code. This paper proposes the initial acquisition model with repeat error control device that is good for perfomance. The hardware is implemented by TMS320c30

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.9A
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• pp.891-899
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• 2008

The cdma2000 1xEV-DO system controls the data rates of mobile terminals based on a binary overload indicator from the base station and a simple probabilistic model. However, this traffic control scheme has difficulty in controlling the reverse-link traffic load effectively and in guaranteeing a stable operation of the reverse link because each mobile terminal determines the next data rate autonomously. This paper proposes a new trafRc control scheme to improve the system stability, and analyzes the proposed scheme by modeling it as a discrete-time Markov process. The numerical results show that the maximum data rate of the proposed scheme is much higher than that of the conventional one. Moreover, the proposed scheme does not modify the standard physical channel structure, so it is compatible to the existing 1xEV-DO system.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.834-837
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• 2011

AMI 시스템은 정보통신 기술과 전력망의 융합으로 탄생한 새로운 형태의 차세대 전력망인 스마트그리드의 핵심기술 중 하나이다. AMI 시스템의 부하 제어 및 수요 측정, 미터링, 과금 등을 위한 다양한 유 무선 통신기술(ZigBee, PLC, Binary CDMA 등)을 적용함에 있어 기존에 제시된 AMI 네트워크 보안 위협에 따른 취약점은 스마트그리드 전체 네트워크의 보안사고를 유발할 수 있다. 본 논문은 AMI 시스템 상에서 ZigBee, Binary CDMA와 같은 무선 네트워크의 적용으로 인한 보안특성을 분석하고 보안 요구사항에 대한 대응방안을 제시한다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.9
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• pp.32-39
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• 2006

In this paper, an iterative subspace-based calibration algorithm for a CDMA-based antenna array in the presence of unknown gain and phase error is presented. The algorithm does not depend on the array geometry and does not require a prior knowledge of the Directions Of Arrival (DOA) of the signals. The method requires the code sequence of a reference user only. The proposed algorithm is based on the subspace method and root finding approach, and it provides estimates of the calibration vector, the DOA and the channel impulse response, by using the code sequence of a reference user. The performance of the proposed algorithm was investigated by means of computer simulations and was verified using field data measured through a custom-built W-CDMA test-bed. The data show that experimental results match well with the theoretical calibration algorithm. Also, teh study propose an efficient algorithm using the simulated annealing technique. This algorithm overcomes the requirement of initial guessing in the subspace-based approach.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5C
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• pp.313-319
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• 2005

In this paper, we propose a class of polyphase signature sequences, whose general odd correlation properties are useful for 4-phase signaling systems. The performance of the direct sequence code division multiple access (DS/CDMA) systems using the proposed sequences is compared with that using binary pseudo-noise sequences. The performance of the system using the proposed sequence is shown to be better than that using other conventional sequences both from the worst-case analysis and bit error rate simulations.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.2019-2022
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• 2002

This paper presents design of spreading codes for asynchronous DS-CDMA systems. We have been trying to generate maximal-period sequences based on one-dimensional maps with finite bits whose shapes are similar to piecewise linear chaotic maps. We propose an efficient search algorithm finding such mammal-period sequences. This algorithm makes it possible to find many kinds of maximal-period sequences with sufficiently long period for CDMA applications. We also investigate bit error rate(BER) in asynchronous DS-CDMA systems using the maximal-period binary sequences by computer simulations.