• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.31-34
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• 1999

In this paper, the improved initial cell searching algorithm is proposed for 3GPP W-CDMA system. The key objective of the proposed algorithm is to utilize the reliability of the first stage of cell searching algorithm in order to accomplish the second stage. So the proposed algorithm makes the mobile station transfers to the second stage from the first stage, just after the slot synchronization is declared successively at the same time-offset. In order to compare the proposed algorithm with the conventional one, the simulations are accomplished for cell search algorithm for 3GPP W-CDMA systems in the multipath Rayleigh fading channel. Some parameters are also presented for the better performance in the initial cell searching algorithm.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.286-289
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• 2003

In this paper, the performance of W-CDMA system with smart antenna is analyzed for angular spread in spatio-temporal wideband vector channel. We consider correlation between any two elements of antenna array, the angle spread of multipath, and structure of antenna array in this channel model. And each multipath is assumed as a reflective wave from only one direction. Several multipaths within one chip are distinguished into each one and the strongest signal is selected. As a result, the performance of the W-CDMA system with smart antenna in spatio-temporal wideband vector channel has been considerably improved in proportion to the increase of angular spread.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.389-393
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• 2003

This paper describes the design of enhanced TSSI RF Power Detector which has wide dynamic range using switch and Log amp. This Power Detector consists of low and high gain loops, and they adaptively switched by output DC voltage which is proportioned to input power level. Because Power Detector needs to separate the channel, so architecture is heterodyne system having 70MHz intermediate frequency. This proposed RF Power Detector is settle to the satisfaction of Closed loop power control system for W-CDMA optic repeater, and the obtained dynamic range cover the higher than 50dB.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.8 no.4
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• pp.201-206
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• 2009

The third generation mobile communications system requiring the reliable multimedia data transmission has provided with the reliable voice, data and video services over the variable propagation environment. However the broadband wireless multiple access technologies cause Inter Symbol Interference (ISI) or Multiple Access Interference (MAI) to degrade the performance of W-CDMA (Code Division Multiple Access) system. Constant Modulus Algorithm (CMA) which is frequently used as the adaptive blind equalizers to remove the interfering signal has ill-convergence phenomenon without proper initialization. In this paper, new blind equalization method based on conventional CMA is proposed to improve the channel efficiency, and through computer simulation this is tested over the time varying fading environment of mobile communication system. Consequently, new blind equalization method into concatenated Kalman filter with CMA is verified better than conventional CMA through adopting minimum mean square errors and eye-pattern obtained from algorithm are compared.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.265-268
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• 2003

In this paper, we propose new simple and efficient stopping criteria for W-CDMA turbo decoding. The new criteria are based on the sum of logarithm of absolute extrinsic information values and the count of one-estimations calculated after each component decoder. The calculation of the proposed criteria can be made simpler by summing one of ten values without any penalty. This Proposed method can be implemented with negligible overhead and no extra memory. Simulation results on W-CDMA standard shows that the number of iterations required is reduced compared to the existing stopping criteria without degrading the BER performance. Reduced iterations and simple operations make the proposed criteria desirable for low-power turbo decoder.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.10A
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• pp.775-779
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• 2003

A spatio-temporal searcher structure for 3rd generation W-CDMA systems is proposed to enhance the detection capability of the multi-path searcher for the desired signal. This searcher employs the spatio-temporal signal structure to search for newly emerging multipath signals. The proposed multi-path searcher provides better detection capability andthus reduces the mean acquisition time. The detection and false alarm probabilities of new and conventional schemes are calculated and numerical examples of mean acquisition time are given thereafter.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.7
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• pp.723-730
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• 2007

This paper shows how the ACLR of power amplifier can be reduced by using Anti-phase IMD linearization technique which generate anti-phase IMD in the driver stage compare to output stage's IMD. And design process proposed. From the experimental result of W-CDMA 4FA input signal, this amplifier has ACLR -55 dBc@5 MHz offset at 30 watts average power. Compare to optimum matching technique to get maximum power gain, this technique has been improved ACLR by 12 dBc. Also this amplifier meets 50 watts average output power amplifier specification in domestic market.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.10
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• pp.9-17
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• 2000

In this paper, the improved initial cell searching algorithm is proposed for 3GPP(The third Generation Partnership Project) W-CDMA system. The key objective of the proposed algorithm is to reduce searching slot and to increase the reliability in the first stage of cell searching algorithm in order to accomplish the second stage. So the proposed algorithm makes the mobile station transfers to the second stage from the first stage, just after the slot synchronization is declared successively at the same time-offset. In order to compare the proposed algorithm with the conventional one, the simulations are accomplished for cell search algorithm for 3GPP W-CDMA systems in the multipath Rayleigh fading channel. The first stage of conventional algorithm is also analyzed in a Rayleigh fading channel in order to prove simulation to be reasonable. In this paper, the proposed algorithm presents the better performance than conventional one. We also propose some parameters for optimal performance.

• Journal of Korea Society of Industrial Information Systems
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• v.11 no.4
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• pp.112-120
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• 2006

Multicarrier code division multiple access(MC-CDMA) system that combines multicarrier modulation with CDMA offers robustness to frequency selective fading and can support higher rate data transmission with higher spectral efficiency. A new asynchronous MC-CDMA system to implement multiple data rate communications is proposed in this paper. In a W-CDMA downlink the orthogonal variable spreading factor(OVSF) code is used for variable spreading factor for various multimedia traffic. Proposed system utilizes the OVSF code that generated by generation property for spreading. The proposed MC-CDMA system use different lengths of OVSF code as a spreading code according to their data rate. The groupwise processing is accomplished by code grouping in OVSF code generation tree. For the analysis of average BER performance, numerical method and computer simulation were used. We also compare the system performance with that of a single rate MC-CDMA system used orthogonal code as a spreading code.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.6
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• pp.120-128
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• 2010

In this paper, equivalent isotropic radiated power (EIRP) of six mobile phones made by two national companies were measured in order to introduce power limit of mobile phones for national CDMA, PCS and WCDMA applications. The measurement has been conducted in a full anechoic chamber and used antenna substitution method. From the measured results, the measured power of the mobile phones are compared by power limit regulations of mobile phones for USA, Japan and Europe. Finally, we propose power limits of 2 W ERP for CDMA phones, 2 W EIRP for PCS phones, and 2 W EIRP for WCDMA phones, respectively.