• 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.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.6 no.4
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• pp.3-38
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• 1996

The mobile station shall convolutionally encode the data transmitted on the reverse traffic channel and the access channel prior to interleaving. Code symbols output from the convolutional encoder are repeated before being interleaved except the 9600 bps data rate. All the symbols are then interleaved, 64-ary orthogonal modulation, direct-sequence spreading, quadrature spreading, baseband filtering and QPSK transmission. The sync, paging, and forward traffic channel except the pilot channel in the forward CDMA channel are convolutionally encoded, block interleaved, spread with Walsh function at a fixed chip rate of 1.2288 Mcps to provide orthogonal channelization among all code channels. Following the spreading operation, the I and Q impulses are applied to respective baseband filters. After that, these impulses shall be transmitted by QPSK. Authentication in the CDMA system is the process for confirming the identity of the mobile station by exchanging information between a mobile station and the base station. The authentication scheme is to generate a 18-bit hash code from the 152-bit message length appended with 24-bit or 40-bit padding. Several techniques are proposed for the authentication data computation in this paper. To protect sensitive subscriber information, it shall be required enciphering ceratin fields of selected traffic channel signaling messages. The message encryption can be accomplished in two ways, i.e., external encryption and internal encryption.

• Journal of the Korea Society of Computer and Information
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• v.14 no.7
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• pp.57-64
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• 2009

Based on this article, I have analyzed the OFDM system which applies three types of equalizer forms in the two-path channel of the microwave baseband. The Two-path channel of microwave baseband had been simulated through the Rummler channel. In the Two-path channel, the OFDM system which has three forms of equalizer has been analyzed and the result is, equalizer 1-tab has great improvement in efficiency compared with Pre-FFT 11-tab which has noise power ratio less than 18dB. On the contrary, if the symbol energy to the noise ratio is more than 18dB, the equalizer which applies Pre-FFT 11-tab has greater efficiency compared to the equalizer which applies 1-tab frequency. Last but not least, the OFDM system which applies Dual equalizer has better efficiency compared to the system which has 1-tab frequency and equalizer which applies Pre-FFT 11-tab.

• Journal of IKEEE
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• v.2 no.1 s.2
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• pp.1-14
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• 1998

In this paper, Antenna, LNA, Mixer, VCO, and Modulation/Demodulation in Baseband processor which are the RF main components in Wireless LAN system for ultra high-speed communications network are studied. Antenna bandwidth and selective fading due to multipath can be major obstacles in high speed digital communications. To solve this problem, wide band MSA which has loop-structure magnetic antenna characteristics is designed. Distributed mixer using dual-gate GaAs MESFET can achieve over 10dB LO/RF isolation without hybrid, and minimize circuit size. As linear mixing signal is produced, distortions can be decreased at baseband signals. Conversion gain is achieved by mixing and amplification simultaneously. Mixer is designed to have wide band characteristics using distributed amplifier. In VCO design, Oscillator design method by large signal analysis is used to produce stable signal. Modulation/Demodulation system in baseband processor, DS/SS technique which is robust against noise and interference is used to eliminate the effect of multipath propagation. DQPSK modulation technique with M-sequences for wideband PN spreading signals is adopted because of BER characteristic and high speed digital signal transmission.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.11a
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• pp.30-34
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• 2001

본 논문에서는 근거리에 놓여있는 노트북, 휴대폰, PDA, 혜드셋 등 각종 이동 가능한 장치들을 하나의 무선네트워크로 연결할 수 있는 블루투스의 베이스밴드 시스템 프로토콜 기능을 분석하고 설계하였다. 즉, 전체적인 논리 기능구조를 설계한 후 하드웨어로 구현될 패킷생성 블록, HEC와 CRC 기능블륵, Whitening/Dewhitening 기능블록, FEC 기능블록, 입출력 블록(TX, RX 루틴), 클럭 생성 기능블록, 주파수 선별 기능블록, 오디오 기능블록 그리고, 패킷 제어 블록들의 처리절차를 Verilog HDL 코드로 설계 및 검증하였다.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.5
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• pp.10-23
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• 1996

In this paper, the reverse link performance evaluation with synchronous CDMA is analyzed in the PCS system, which is the schem based on proposed method of KMT-PCS to increase the capacitance of cellular CDMA system. We make the baseband system model of CDMA reverse link, and then analyze system performance and subsystem techniques considering effect of channel and power control that are improtant factor influencing system performance in the PCS system. Based on this result, the paper presents primary technique analyses required at synchronous reverse link proposed by the KMT, which compose of initial synchronization range in initial synchronization step and control signal period in the synchronization maintenance step.

• Journal of Advanced Navigation Technology
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• v.13 no.4
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• pp.482-489
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• 2009

This paper proposes a CW(Continuous-Wave) bio-radar applying a new adaptive noise canceller based on ALE(Adaptive Line Enhancer) which can remove the Gaussian noise and system noise. Recently the research works on this CW bio-radar which can be used to detect heartbeat and respiration are advanced by the university and research facility. Although the researches describe CW bio-radar not only is vulnerable for the Gaussian noise but also has a disadvantage of decreasing the heart-rate accuracy due to the noise, the researches do not demonstrate the effective method for removing the noise component in a baseband signal. In this paper, a CW bio-radar applying the new adaptive noise canceller based on ALE which can remove the noise component is proposed. This paper compares and analyzes the performance for increasing the heart-rate accuracy according to removing the Gaussian noise and system noise in the baseband signal through the quadrature receiver which can alleviate the demodulation sensitivity to target position.

• Journal of Korea Multimedia Society
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• v.6 no.3
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• pp.436-443
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• 2003

A digital video watermarking algorithm is proposed that uses HVS and DWT. In this algorithm, each video frame is decomposed into four-level by DWT which reveals the characteristics of the human eyes and watermark is embedded into DWT coefficients using HVS. For robustness, the lowest level subbands which represent the highest frequency component are excluded in watermark embedding step and watermark is embedded into the perceptually significant coefficients (PSCs) of the rest subbands. PSCs of the baseband are selected according to the amplitude of the coefficients and PSCs of the high frequency subbands are selected by successive subband quantization (SSQ). Watermark is embedded into the PSCs of the baseband and high frequency subbands by Weber's law and spatial masking effect, respectively, for the invisibility and robustness. We tested the performance of the proposed algorithm compared with the conventional watermarking algorithm by computer simulation. Experimental results show that the proposed watermarking algorithm produces a better invisibility and robustness than the conventional algorithm.

• Journal of Advanced Navigation Technology
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• v.10 no.1
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• pp.56-62
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• 2006

In this paper, we simulated terrestrial digital broadcasting system and analyzed the performance of 8-VSB signal and carried out baseband simulation of tranceiver modeling by standard parameter and passband simulation for interchannel interference. Also, an error rate equation for fading and interference of 8-VSB signal is derived. As a result, the case not to consider Rician fading, the influence of the interference did not exist if frequency interval fell off over the 20MHz. The case to consider Rician fading, the system had the degradation of the performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.12A
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• pp.2100-2108
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• 2001

A digital image watermarking algorithm is proposed that uses human visual system (HVS) and discrete wavelet transform (DWT). In this algorithm, an image is decomposed into four-level by DWT which reveals the characteristics of the human eyes and watermark is embedded into DWT coefficients using HVS. For robustness, the lowest level subbands which represent the highest frequency component are excluded in watermark embedding step and watermark is embedded into the perceptually significant coefficients (PSCs) of the rest subbands. PSCs of the baseband are selected according to the amplitude of the coefficients and PSCs of the high frequency subbands are selected by successive subband quantization (SSQ). Watermark is embedded into the PSCs of the baseband and high frequency subbands by Weber\`s law and spatial masking effect, respectively, for the invisibility and robustness. We tested the performance of the proposed algorithm compared with the conventional watermarking algorithm by computer simulation. Experimental results show that the proposed watermarking algorithm produces a better invisibility and robustness than the conventional algorithm.