• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.39 no.6
• /
• pp.10-10
• /
• 2002

This paper introduces the high-resolution channel estimation technique which are used to estimate the first arrival multipath delay component. The proposed technique yields the precise estimate of the first time arrival which is directly related to the performance of TDOA-based position location. The proposed technique utilizes the transformed auto-correlation function of received common pilot signal in frequency domain, its samples compose the hermitian Toeplitz matrix at sequel. Then the time delay components could be estimated with precision by the analysis of eigen-structure of corresponding matrix. In this paper, obeying the modified CODIT model, the performance of the PR-IPDL(Pseudo Random-Idle Period Downlink) and TA-IPDL(Time Aligned-Idle Period Downlink considered as 3GPP position location technique will be exploited systematically through the computer simulations with applying the proposed technique.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.39 no.6
• /
• pp.268-276
• /
• 2002

This paper introduces the high-resolution channel estimation technique which are used to estimate the first arrival multipath delay component. The proposed technique yields the precise estimate of the first time arrival which is directly related to the performance of TDOA-based position location. The proposed technique utilizes the transformed auto-correlation function of received common pilot signal in frequency domain, its samples compose the hermitian Toeplitz matrix at sequel. Then the time delay components could be estimated with precision by the analysis of eigen-structure of corresponding matrix. In this paper, obeying the modified CODIT model, the performance of the PR-IPDL(Pseudo Random-Idle Period Downlink) and TA-IPDL(Time Aligned-Idle Period Downlink considered as 3GPP position location technique will be exploited systematically through the computer simulations with applying the proposed technique.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.7B
• /
• pp.695-705
• /
• 2002

In this paper, we propose a simple open loop transmit diversity (TD) scheme for the wideband code division multiple access (W-CDMA) systems in Rician multipath fading channels such as rural area or satellite channels where line-of-sight (LOS) paths are in presence. The proposed scheme does not require any pre-processing of transmit data, resulting in simpler structure as compared to conventional closed loop transmit adaptive array (TxAA) and open loop space-time transmit diversity (STTD). We analytically derive the probability density function of signal-to-noise ratio at the Rake receiver output and the uncoded bit error rate performance of the proposed scheme. Extensive simulation is Performed to verify the analytical performance of the proposed scheme under typical Rician multipath fading channel environments. Moreover, comparative results with the conventional TxAA and STTD are also provided. Simulation results show that the proposed scheme shows slightly better performance than the conventional open loop STTD under the channels with very weak LOS components, however, it significantly outperforms the STTD under the channels with dominant LOS components, and achieves a close performance of ideal closed loop TxAA.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.18 no.3 s.118
• /
• pp.298-304
• /
• 2007

In this paper, the antenna which has a multiband operation (GSM850, EGSM, DCS1800, USPCS, W-CDMA) is proposed. This antenna was designed by the commercial software HFSS 3-D EM simulator, and it is organized by using a meander branch structure which has a via and lines on FR-4$(\varepsilon_r=4.4)$ substrate. Especially, it has a gap feeding structure which makes good operation at overall bandwidth. The designed antenna is manufactured by PCB processing, and measured by using a network analyzer and a test chamber. The manufactured antenna with the dimension of 8 mm width, 20 mm height and 3.2 mm thickness is able to applied as an internal antenna for multiband mobile phones.

• Journal of electromagnetic engineering and science
• /
• v.14 no.4
• /
• pp.393-398
• /
• 2014

A highly efficient dual-mode linear CMOS stacked-FET power amplifier (PA) is implemented for 3G UMTS and 4G LTE handset applications. High efficiency is achieved at a backed-off output power ($P_{out}$) below 12 dBm by employing an active-bypass amplifier, which consumes very low quiescent current and has high load-impedance. The output paths between high- and low-power modes of the PA are effectively isolated by using a bypass switch, thus no RF performance degradation occurs at high-power mode operation. The fabricated 900 MHz CMOS PA using a silicon-on-insulator (SOI) CMOS process operates with an idle current of 5.5 mA and shows power-added efficiency (PAE) of 20.5%/43.5% at $P_{out}$ = 12.4 / 28.2 dBm while maintaining an adjacent channel leakage ratio (ACLR) better than -39 dBc, using the 3GPP uplink W-CDMA signal. The PA also exhibits PAE of 35.1% and $ACLR_{E-UTRA}$ of -33 dBc at $P_{out}$ = 26.5 dBm, using the 20 MHz bandwidth 16-QAM LTE signal.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.21 no.2
• /
• pp.46-53
• /
• 2007

Extension of the mobile communication and the rapidly developing services connected with wireless multimedia(W-CDMA, DMB, Wibro, and so on) need great many base station transceiver systems, antennas, and many signal transmission line to embody these services. The min communication appliances system is exposed always in danger of transient overvoltage by direct stroke or induced lightning surge flowing in through antenna because the antenna of base station transceiver system or relay equipment is combined with expensive communication network equipments through signal transmission line. Now, gas discharge tube(GDT) or narrow band stub arrestor which is used by the surge protector for communication use is exposing limitations as for lightning surge protective means of the communication facility with high speed and wide frequency band. Therefore, for improving performance of surge arrestor, we applied ceramic filter which can reduce lightning surge invading from antenna effectively, and proved that ceramic filter is effective in residual voltage reduction through the experimental research.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.8 no.4
• /
• pp.761-766
• /
• 2004

Rayleigh fading due to multi-path degrades the mobile service quality, especially high data rate mobile services such as 1xEVDO and W-CDMA. The field test showed that down load date rate of 1xEVDO is seriously affected by Rayleigh fading. To reduce the effect of Rayleigh fading, transmit diversity was implemented in RF repeater. In field test, transmit diversity function increased the data rate about twice comparing with no transmit diversity repeater. Recently high data rate service is getting more important, so transmit diverstiy function will be an important function in repeater.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.11 no.4
• /
• pp.67-75
• /
• 2001

3GPP proposed f8 and f9 algorithms based on the block cipher KASUMI to provide the data confidentiality and integrity over a radio access link for IMT-2000(W-CDMA). Also 3GPP proposed Milenage algorithm based on the block cipher Rijndael to provide an example set for 3GPP authentication and key generation functions. In order to analyze the security of 3GPP algorithms, we must go ahead an analysis of security of KASUMI and Rijndael. Since S-box is an important point of security of block cipher, in this paper we analyze the S-boxes of KASUMI and Rijndael and compare the S-boxes of KASUMI with the S-box of Rijndael. Although KASUMI S9-box is bad for AC and SAC, we find that AC of KASUMI FI function containing S7-box and S9-box is equal to AC of Rijndael S-box and SAC of KASUMI FI function is better than SAC of Rijndael S-box.

• 한국정보통신설비학회:학술대회논문집
• /
• 2005.08a
• /
• pp.124-127
• /
• 2005

국내에서는 언제 어디서나 휴대용 단말을 이용하여 저렴한 요금으로 고속의 무선인터넷을 사용할 수 있는 휴대인터넷 서비스를 2006년부터 서비스 할 계획이다. 앞으로 서비스 될 WiBro 휴대인터넷 서비스 방식은 기존 이동통신 방식과 달리 RF 송신 주파수와 수신 주파수가 동일한 TDD (time division duplexing) 방식을 사용한다. WiBro 무선통신 기지국 장비에 있어서도 기존 CDMA 이동통신 기지국 장비에서와 마찬가지로 RF Power Amplifier (PA)가 매우 고가의 핵심 부품이라 할 수 있다. 물론, 기존 FDD (frequency division duplexing) 방식의 CDMA 기지국 PA와 달리 WiBro용 기지국 PA는 TDD 신호를 처리할 수 있는 새로운 기술을 필요로 한다. TDD 방식인 WiBro 기지국용으로 사용할 수 있는 새로운 2.3 GHz 42 W PA를 설계, 제작한 결과를 본 논문에서는 발표하고자 한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2002.11a
• /
• pp.209-212
• /
• 2002

The realization for code domain analyzing system on WCDMA is presented. This system is realized with the RF, FPGA and DSP processor. The FPGA firgures out the scambling code, and DSP produces the power of code domain using OVSF. The experiment results allow the code domain power accuracy to keep $\pm$1dB low. This system leads to split the text, sound and image signal.