• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.25-28
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• 2000

In this paper, we assume various number of multipaths in one chip duration according to spreading bandwidth. And we take into account of the effects of autocorrelation and relative phases among multipath components within one chip duration, and analyze fading effects. We derive the average error probability for different number of users. Then, we compare the performance of W-CDMA systems with different bandwidths. From the simulation results for different band-widths, wideband CDMA systems show better performance than narrowband CDMA systems in vehicular and pedestrian environments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.8B
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• pp.1371-1382
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• 2000

IMT-2000 system is the third generation mobile communication system which aims at mobile multimedia services with global roaming. Like 2nd generation system, the IMT-2000 system is also under strong influence of interferences among active subscribers in the multiple access environment. That is, in multiple access environment, signals from one subscriber could interfere with others in the same cell or in the neighboring cells. The interference control in the IMT-2000 systems is much more difficult then the interference control in the 2ndgeneration CDMA cellular systems, since the transmitted power of a subcriber might be different that of others in the IMT-2000 system. In this paper, a parallel interference cancellation with traffic discrimination is proposed which can effectively cancel interferences by grouping the subscribers into several equi-power classes. As a conclusion, simulation results show that the proposed method outperforms the conventional partial PIC scheme in several aspects.

• Information and Communications Magazine
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• v.15 no.11
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• pp.13-31
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• 1998

이 글은 IMT-2000 무선 접속 규격 후보로서 ITU-R에 제출된 다중 대역 DS-CDMA 시스템인 Global CDMA Ⅰ에 관하여 설명하고, 그 규격에 따라 기저 대역 5MHz에 대하여 8Kbps 음성과 128Kbps 영상 서비스를 구현한 테스트 베드와 향후 개발 방향에 관한 내용이다.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.261-261
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• 2004

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.825-828
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• 1999

A Viterbi Decoder for IMT2000 Mobile Station based on cdma200 is implemented in this paper. There are fundamental traffic channel, supplemental traffic channel for user data transmission and dedicated control channel for signal transmission in cdma2000. This decoder can decode these channels simultaneously, and support l/2, l/3, 1/4 code rate decoding. In case of fundamental channel decoding, it needs about 1100 logic cells and 30000 bit memory block.

• Proceedings of the Korean Information Science Society Conference
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• 2000.04a
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• pp.238-240
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• 2000

현재 IMT-2000서비스를 위한 패킷 전송 망의 표준화는 특히 북미 방식의 3세대 패킷 데이터 시스템과 유럽의 GPRS, 이 두 가지 분야를 중심으로 연구가 진행되고 있다. 지금까지 국내의 이동통신은 CDMA를 중심으로 발전해 왔고 WAP 표준이 나온 후로도 계속해서 CDMA방식에 WAP을 적용하려는 노력이 계속되고 있다. 하지만 WAP은 GSM의 성능을 개선하기 위해 등장한 것이고 특히 GSM의 새로운 기술은 GPRS에 WAP을 적용시키면 이동 간에 인터넷 서비스는 물론 다양한 응용을 윤활하게 서비스할 수 있다. 본 논문에서는 GPRS 기반 하에 WAP을 연동시킬 수 있는 방안을 기술하고자 한다.

• Review of KIISC
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• v.11 no.6
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• pp.63-73
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• 2001

3세대 방식인 IMT-2000 (International Mobile Telecommunication-2000)시스템은 GSM이나 IS-95 CDMA 시스템과 같은 2세대 이동통신 시스템과 비교하여 고속의 멀티미디어 서비스 제공 및 글로벌 로밍을 특징으로 한다. W-CDMA 방식 IMT-2000에 대한 인증 메커니즘은 3GPP TSG SA WG3에 의해서 개발되었다. 본 논문에서는 3GPP에서의 AKA(Authentication & Key Agreement)를 분석하고 이를 통해 안전성 분석 및 취약성을 분석한다. 본 논문에서 제기하는 안전성 분석 및 취약성 분석은 앞으로의 더 좋은 서비스를 제공할 것이다.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.49-52
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• 2000

The Multi-Code CDMA systems that are proposed as an effective transmission methodology in the IMT-2000 systems allow higher rate services under the IS-95 CDMA infrastructure. The Multi-Code CDMA systems convert the higher rate data into the lower rate by serial to parallel operation and spread the converted data streams by the multiple walsh codes, and its mobile receiver needs multiple walsh generators and data correlators to demodulate simultaneously multiple walsh code channels. Therefore, the number of data correlators is increased as the number of traffic channels increases. In this paper, we proposed the new structure of the data correlators using walsh overlay coding, the shared accumulator, and FWHT(Fast Walsh Hadamard Transform) algorithm for reducing the bottle-neck effect resulting the increase of the number of data correlators.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.9B
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• pp.771-777
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• 2004

In a COMA system, the capacity is variable and mainly depends on multiple access interference. The multiple access interference has a deep relationship with transmitted or received power. The capacity of COMA2000 system is considered to be limited by the forward link capacity. In this paper, we show that the forward link cell load can be represented by the total transmitted power of base station and we propose a forward link call admission control (CAC) strategy for COMA2000 system. The proposed call admission scheme adopts the rate control algorithm for data call. This call admission scheme enables the system to utilize radio resource dynamically by controlling data rate according to the cell load status, and enhance the system throughput and grade of service (GoS). quality of service(QoS) such as blocking and outage probability.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.6
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• pp.53-65
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• 2001

Authentication mechanism for W-CMDA IMT-2000 system is developed by 3GPP TSG SA WG3. We simulated the mechanism and algorithms. In this paper, we overview 3GPP authentication procedures and present results of our simulation. We validate the mechanism and parameters transmitted during authentication procedures and we also discuss parameters which are unclear in specification.