• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.125-128
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• 2000

In this paper, we derive forward link Erlang capacity reflecting both outage probability and blocking probability of each traffic type in mixed traffics environment. We firstly determine the number of available virtual trunks of the forward link from a circuit switching perspective. Then, capacity sharing model and generalized Erlang model are employed to derive joint Erlang capacity of various traffics types.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.222-225
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• 2000

In this paper, a synchronous CDMA system accepted for the cdma2000 standard is simulated to propose optimized reverse link power ratio and channel estimation lengths. Differently from IS-95, the pilot channel is used in the proposed system to estimate fading channel, so optimized estimation lengths are needed. Therefore, in this paper we analyze optimized estimation lengths which is needed to decide the power ratio of pilot channel and fundamental channel. From fixed estimation lengths, we calculate FER with various power ratio values.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4B
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• pp.291-297
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• 2002

Due to the increasing demand for high data multimedia service, there has been progressing study of adaptive smart antenna to increase both the performance and capacity using limited wireless resource. IS-95 scheme in the origin of cdma2000 of IMT-2000 standard uses signals of spreading and Walsh-Orthogonal Modulation in reverse link. But, in the case of reverse lint there exists difficulty in synchronous of signals transmitted from users. Therefore, orthogonality between users is not satisfied. So, asynchronous MC-CDMA scheme may yield low performance. In this paper, MC/DS-CDMA scheme to reverse link transmission in adaptive array antenna environment is proposed for spreading the S/P-converted data streams using a given spreading code. Due to frequency diversity effect, simulation results show that the proposed system provides improved BER performance and narrow band interference supple psi on.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.4
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• pp.668-675
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• 2001

Recently, the performance of the commercial PCS(Personal Communication Service) system has been improved to the uppermost limit and ultimately the next generation mobile communication is to be realized by IMT-2000 (International Mobile Communication-2000) to provide multimedia services. Therefore, the new type receiving system is researched actively and one of the most important part in a receiver is direct conversion method. The direct conversion method is suitable for low power consumption, small size, MMIC, and low price, which is to be adopted to the next generation mobile communication systems. In this case, however, several problems occur due to DC-offset. The DC-offset suppresses amplification of the required signal because of the leakage signal of frequency synthesizer in the system. In this thesis, the removing method of DC-offset was considered. There are four removing techniques of DC-offset, which are AC-coupling, large capacitor, DC-feedback loop, and DC-free coding. Among these, the AC-coupling method is the most simplest method and the DC-feedback loop method has the best performance. Then, the performance of the AC-coupling method and DC-feedback loop method are evaluated by HP's ADS simulation tool. As a result, the AC-coupling method cannot be used to the digital communication systems due to data loss. On the other hand, it was confirmed that the DC-feedback loop method is suitable for the direct conversion receiver.

• Information and Communications Magazine
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• v.14 no.11
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• pp.22-28
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• 1997

ETSI SMG plays a key role at the development of standards for the UMTS Universal Mobile Telecommunications System, a set of standards aimed at the global market. It will be a real Third Generation Global System for Mobile CommunlcaUons adding new features and Introducing relevant technological InnovaUons while evolving from both GSM and ISDN networks. UMTS Is based on the carefully selected market requirements and belongs to the IMT-2000 family. UMTS standardlsaUon Is a market driven process being developed In a close co-operatlon with the UMTS Forum and GSM MoU.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.5
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• pp.970-976
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• 2004

In this paper, we analyze channel estimation algorithms in a RAKE receiver with MRC. There are 3 popular channel estimation algorithms, which are WMSA(Weighted Multi-Slot Averaging) algorithm, EGE(Equal Gain Estimation) algorithm, SSE(Symbol-to-Symbol Estimation) algorithm. We analyze asynchronous IMT-2000(3GPP) which employ 3 different channel estimation algorithms by HP-ADS(Advanced Design System) simulation tool. We used lakes fading channel model for the analysis. from simulation results, we could observe that the performance of WMSA algorithm is better than others in low Doppler effect(3Km/h). However, in the case of high Doppler effect(120km1h), the EGE algorithm is more efficient. In this case the simple estimator with EGE algorithm seems to be more useful.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.5C
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• pp.601-610
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• 2004

In this paper, the performance of an adaptive array antenna using Constant Modulus Algorithm (CMA) based on the signal structure for the IMT-2000 3GPP specification reverse link of an asynchronous direct sequence code division multiple access (DS-CDMA) system are evaluated. In addition, the performance is compared with the array antenna using Least Mean Square (LMS) based on the training signal. The simulation parameters such as the number of multipath, mu10pa1h intensity profiles between path, spreading gain and multiuser etc., are considered in the Monte Carlo simulation. Simulation results demonstrate an adaptive array antenna using CMA may give more capacity gain than the amy antenna using LMS in the case of multipath fading channel.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7A
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• pp.996-1004
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• 1999

In this paper, we evaluate the performance of reverse link synchronous CDMA with orthogonal spreading and Rake combining, and compare this to that of an asynchronous transmission under Rayleigh multipath fading environments. The link performance is evaluated in terms of average bit error rate (BER) and capacity, assuming ideal BPSK data modulation. The focus of this paper is on the impact that the multipath intensity profile (MIP) shape and number of taps in Rake receiver have on the performance of synchronous transmission. The results show the reverse link synchronous transmission can always achieve smaller BER than the asynchronous transmission even if inter-path interference exists.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.6
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• pp.645-655
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• 1997

In this paper, the performance of the noncoherent code tracking loop designed at baseband for CDMA applications is analyzed in detail and is confirmed by computer simulations. Analytical closed-form formula for jitter variance is derived for AWGN channel environments as a function of pulse shaping filter, timing offset, signal-to-interference ratio, and loop filter coefficients. The design issue of the loop filter is also addressed with emphasis on the second-order tracking loop. Finally, the performance of the designed tracking loop is examined by computer simulations for both AWGN and Rayleigh fading channels, when applied to the reverse link of the coherent CDMA system for IMT-2000 designed by ETRI.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.355-358
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• 2002

The network functional standard for MNP defines tile network functional structure and information flow to provide Number portability among the imt-2000 mobile phone. In this paper we define network function and system function and processing method of information which will be changed among them. In this paper, we also defines the processing method of SMS.