• TTA Journal
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• s.105
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• pp.177-181
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• 2006

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.4
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• pp.646-651
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• 2003

In this paper, we investigate the performance comparisons of various turbo interleavers which are adopted as a standard such as IMT-2000 and satellite DVB(digital video broadcasting). The bit error rate performance is calculated by the fixed point computer simulations over Rayleigh fading channels. For a fair comparison, the simulation is performed on the basis of equal the interleaver size as we can. From the results, it is shown that the turbo interleaver in W-CDMA outperforms the turbo interleavers in CDMA2000 and satellite DVB. The performance gains are even larger as the interleaver size is increased.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.54-58
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• 2000

멀티미디어 서비스를 제공하기 위한 피코셀(Pico-cell)환경의 IMT-2000(International mobile Telecommunication-2000) 이동통신망 구조를 살펴보면, 셀의 크기가 작기 때문에 이동체의 셀간 이동이 상대적으로 증가해서 잦은 핸드오프 처리로 서비스 중단이 빈번히 발생할 수 있을 뿐만 아니라 자원의 낭비도 많아지게 된다. 이런 문제를 해결하기 위해 셀 간 이동체에 대하여 중단 없는 서비스를 제공하고 멀티미디어 서비스를 효율적으로 채공하기 위하여 멀티캐스트 그룹 선정 방법과 핸드오프 알고리즘을 제안하고 성능을 평가하였다. 제안한 방법은 이동체의 속도와 예상 진행 방향을 애측하여 멀티캐스트 그룹을 결정한다. 결정된 멀티캐스트 그룹을 이용하여 이동체의 속도 증\ulcorner감소에 따라 멀티캐스트 그룹을 조절하여 핸드오프 멀티캐스트로 인한 버퍼 오버헤드를 감소시킴으로서 핸드오프 호의 블러킹을 감소시켜 전체적인 QoS를 향상시킬 수 있다.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.577-580
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• 2003

최근 차세대통합네트워크(NGN), ALL-IP 망 진화 방향과 함께 동기식과 비동기식 IMT-2000 망의 통합(Convergence) 또는 연동(Harmonization)에 관한 연구가 활발히 이뤄지고 있으며, 이동통신 망의 개방화에 대한 분위기가 점차 무르익어 가고 있다. 이러한 추세에 UMTS, cdma2000, WLAN 과 같은 서로 다른 방식의 무선 액세스 망으로부터 요구되는 무선인터넷 접속 요구를 하나의 통로로 연결하고 수용할 수 있는 모바일 액세스 통합 게이트웨이가 필요하다. 본 논문에서는 차세대 네트워크 발전 방향과 이동통신 망 개방의 흐름에 맞추어 동기식 망과 비동기식 IMT-2000 망에서 동시에 무선인터넷 서비스 접속을 제공하는 통합 게이트웨이 시스템(A-MiDAS)을 개발하기 위한 형상 설계 방법과 시스템 개발 시 고려사항 등에 대해서 기술한다.

• IE interfaces
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• v.13 no.2
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• pp.178-187
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• 2000

In this paper, we investigate the system performance when the voice traffic is constructed as the ATM Adaptation Layer type 2(AAL-2) and then it is transmitted to the Base Station Controller(BSC) from the Base Station Transceiver Subsystem(BTS) through El link in International Mobile Telecommunication-2000 (IMT-2000) network. For this purpose, we first briefly describe the architecture of the BTS and the BSC, and then model it as a queueing network. By simulation study, we present the required processing time at traffic control blocks and the timeout time which should be set for multiplexing the user packets in the LIU(Line Interface Unit). Further, we evaluate the performance of physical links and the timeout probability that user packets can not be multiplexed within the established timeout time, and the multiplexing gain. Finally, we present the number of voice users who can be simultaneously admitted on one El link and 99.9% value of the transmission delay from the Radio Channel Element(RCE) to the Selector & Transcoder Subsystem(STS).

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.29-33
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• 2001

본 논문은 IMT-2000용 동기(cdma2000) 및 비동기(W-CDMA) 통신시스템간의 가드 밴드와 전파간섭에 관한 것으로, ITU-R SM.337-4 권고(안)과 수신필터 특성을 반영한 ACIR(Adjacent Channel Interference Ratio) 표준규격을 IMT-2000의 특징인 다층 셀 구조에 적용하여 두 시스템간의 가드밴드로 1.5625MHz를 제안했다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.2
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• pp.56-63
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• 2003

We investigate some implementation factors that affect the performance of multi-rate parallel interference cancellers (PICs) for the international mobile telecommunications-2000 (IMT-2000) 3rd-generation partnership project (3GPP) system. We consider the simple multi-rate PIC [1,2] that can remove effectively multiple access interference (MAI) through block-based detection and sample-based cancellation in asynchronous user environments. The PIC structure has significantly lower complexity as compared with that of the existing scheme, especially as the number of users increases. We analyze the effects of timing error, oversampling rate, unsynchronized users and/or outer-cell interference, and the number of Quantization bits on the PIE performance through extensive computer simulations. The models for such factors and the optimum parameters are drawn. Finally, we evaluate the receiver complexities of the PIC receivers employing using the advanced removal scheme.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.37 no.2
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• pp.54-61
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• 2000

This paper presents the performance evaluation of channel estimation algorithm using RLS algorithm lot W-CDMA reverse link over Rayleigh fading channels. By obtaining BER(Bit Error Rate) performance through computer simulations, the RLS(Recursive Least Square) algorithm is compared with the existing WMSA(Weighted Averaging)(K=1,3) and constant gain algorithm. The channel structure, modulation and pilot patterns are applied to the ARIB (Association of Radio Industries and Business) and 3GPP (3rd Generation Partnership Project) ITU-R proposal for the IMT-2000. The BER performance of RLS algorithm with linear interpolation is similar to that of WMSA(K=1) and slightly superior to that of constant gain algorithm at low Doppler frequencies. Also, RLS algorithm performance is better than that of the WMSA(K=1,3) and constant gain algorithms about 4dB at BER=2.0$\times$$10^{-2}$ and Doppler frequencies $F_D$=320Hz. With increasing Doppler frequency, therefore, the BER performance of RLS algorithm with linear interpolation is superior to WMSA(K=L.3) and constant rain algorithms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.8B
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• pp.819-825
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• 2002

Resolution 221 requests the ITU-R to conduct studies, as a matter of urgency, on the feasibility of utilizing HAPS system as a base station to provide IMT-2000 services. And HAPS base stations should not cause harmful interference to the cellular IMT-2000 services. To study on the interference between HAPS system and cellular system is divided into two cases. One is the interference into HAPS system from the cellular system and the other is the interference into the cellular system from HAPS system. Since the former case has been already studied[1]. this paper describes the interference the interference to the noise power ration(I/N) with various parameters, such as the transmitting power, the number of users per cell, maximum antenna gain and the multibeam cell radius of HAPS. With the proposed estimation, we can determine the optimum values of various parameters in HAPS IMT-2000 system.

• 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.