• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.11A
• /
• pp.1081-1091
• /
• 2005

Unlike conventional DVB-T transmission with the streaming method, DVB-H system based on the IPDC(IP Data Casting) method uses Time-slicing scheme to achieve the maximization of portability by reducing the power consumption of a receiver. To enhance the power efficiency of the receiver, Time-slicing scheme controls the receiver operation to perform only for corresponding burst in specific time slot. The additional power saving can also be achieved by reducing the required time for synchronization. In this paper, we propose a fast scattered pilot synchronization algorithm, which detects the pilot pattern of currently received OFDM symbol. The proposed scheme is based on the correlation between the adjacent subcarriers of potential scattered pilot position in two consecutively received OFDM symbols. Therefore, it can reduce the time for the scattered pilot synchronization within two symbols as com-pared with the conventional method used for DVB-T. And the proposed algorithm has better performance than the two schemes proposed by Nokia for DVB-H and the method using correlation with reference signal. Extensive com-puter simulation is performed based on ETSI EN300 744 ETSI and performance results show that the proposed algorithm has more efficient and stable operation than the conventional schemes.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
• /
• v.8 no.3
• /
• pp.111-115
• /
• 2009

Cognitive Radio (CR) technology is proposed for using the unused spectrum band efficiently because of the spectrum scarcity problems. Spectrum sensing is one of the most challenging issues in cognitive radio system. In this paper, we focus on the signal detection of WiBro system band. As most of the modulated signals can be treated as cyclostationary random process, we can detect the signal of the OFDM signals in WiBro system. OFDM symbols using WiBro system have several pilot subcarriers and periodic pilots have cyclostationary characteristic. To improve the detection performance, we get diversity gain using multiple antennas.

• Journal of Microbiology and Biotechnology
• /
• v.16 no.12
• /
• pp.2000-2003
• /
• 2006

A gene (GenBank AF096282) coding for a $\alpha$-glucosidase (TcaAG, EC 3.2.1.20) from Thermus caldophilus GK24 was expressed in Saccharomyces cerevisiae, a generally recognized as safe (GRAS) host. The thermostable $\alpha$-glucosidase was produced inside of the GRAS host at 0.04 unit/mg-dry cell by the constitutively expressing ADH1 promoter and at 1.2 unit/mg-dry cell by the inductively expressing GALl0 promoter, respectively. No $\alpha$-glucosidase activities were found in the medium when the MF-alpha signal sequence from S. cerevisiae or $\alpha$-amylase signal sequence from Aspergillus oryzae were fused before the $\alpha$-glucosidase gene for the secretion.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.16 no.4
• /
• pp.12-19
• /
• 2008

GIOVE-B is the second experimental Galileo satellite for the Galileo In-Orbit Validation, which was launched by a Soyuz/Fregat rocket departing from the Baikonur cosmodrome in Kazakhstan on 27 April and now operated successfully. This paper presents the results obtained from processing of the E5a signal transmitted from the GIOVE-B. The acquisition and tracking of the data and pilot channels are performed by the E5a software receiver implemented by ETRI. Moreover, the paper suggests the GIOVE-B E5a-I/E5a-Q secondary code, which is determined by analyzing the correlation output of the primary correlator using the primary code.

• Journal of Communications and Networks
• /
• v.11 no.1
• /
• pp.42-46
• /
• 2009

Superimposed training (SIT) design for estimating of time-varying multipath channels is investigated for mobile orthogonal frequency division multiplexing (OFDM) systems. The design of optimum SIT consists of two parts: The optimal SIT sequence is derived by minimizing the channel estimates' mean square error (MSE); the optimal power allocation between training and information data is developed by maximizing the averaged signal to interference plus noise ratio (SINR) under the condition of equal powered paths. The theoretical analysis is verified by simulations. For the metric of the averaged SINR against signal to noise ratio (SNR), the theoretical result matches the simulation result perfectly. In contrast to an interpolated frequency-multiplexing training (FMT) scheme or an SIT scheme with random pilot sequence, the SIT scheme with proposed optimal sequence achieves higher SINR. The analytical solution of the optimal power allocation is demonstrated by the simulation as well.

• Journal of information and communication convergence engineering
• /
• v.5 no.4
• /
• pp.328-332
• /
• 2007

The structure of MMSE receiver frontended by CMA array working in CDMA forward link is proposed. By using the despreaded pilot signal of forward link as a reference signal, CMA array can capture multi-path signals securely even in severely faded mobile channel. The remaining MAl (Multiple Access Interference) is cancelled by the cascaded MMSE receiver. Through computer simulation, it is proved that the proposed system shows much better BER performance than any other systems. As a mobile based spatio-temporal receiver, the proposed system also reduces implemental cost and complexity by adopting the simplest algorithm for its spatial and temporal domain processing.

• ETRI Journal
• /
• v.29 no.4
• /
• pp.536-538
• /
• 2007

We propose and describe the fabrication of a linear power amplifier (LPA) using a new analog feedforward method for the IMT-2000 frequency band (2,110-2,170 MHz). The proposed analog feedforward circuit, which operates without a pilot tone or a microprocessor, is a small and simple structure. When the output power of the fabricated LPA is about 44 dBm for a two-tone input signal in the IMT-2000 frequency band, the magnitude of the intermodulation signals is below -60 dBc and the power efficiency is about 7%. In comparison to the fabricated main amplifier, the magnitude of the third intermodulation signal decreases over 24 dB in the IMT-2000 frequency band.

• Proceedings of the IEEK Conference
• /
• 2003.07a
• /
• pp.418-421
• /
• 2003

In this thesis, a new channel estimation technique is proposed for orthogonal frequency division multiplexing (OFDM) over time varying channels. The channel estimation algorithm exploits the fact that the estimated channel impulse response (CIR) by using pilot signal is the average value of the CIR variation within an OFDM symbol period. With this fact, the CIR variation is simply estimated through lowpass interpolation of the CIRs of the adjacent OFDM symbols. For signal detection, a time domain equalizer is used in this thesis. Simulation results show that the proposed system improves the bit error rate (BER) over time varying channels.

• Journal of Sensor Science and Technology
• /
• v.16 no.3
• /
• pp.202-210
• /
• 2007

The aim of this study is to acquire useful information of lower urinary tract symptom (LUTS) diagnosis through urophonography signal as a noninvasive method. The hardware and software which could evaluate the function of compensatory hypertrophy with noninvasive and comfortable method was implemented to measure uroflow and urophonography signal during urination. The PSD (power spectrum density) and the log-log plot gradient analysis were accomplished in frequency domain. For evaluation of the system and analysis method, a model system for the lower urinary system of men was used. From the evaluation of the model system, the PDS and the log-log plot gradient were dependent on the occlusion degree significantly. In a pilot study on normal and abnormal male subjects, the PSD and the log-log plot gradient were highly correlated with the artificial urethral obstruction.

• Proceedings of the IEEK Conference
• /
• 2002.07c
• /
• pp.1455-1458
• /
• 2002

In this paper, we propose a modified CP-AFC(Cross-Product Automatic Frequency Control) algorithm to enhance coherent signal detection for WCDMA reverse link receiver. We introduce a moving average filter at the FDD(Frequency Difference Detector) input to increase the number of cross-products, since pilot symbol in WCDMA is not transmitted continuously. We also add normalization algorithm to overcome the conventional CP-FDD's sensitivity to the variance of input signal amplitude and to increase the linear range of S- curve. For rapid frequency acquisition and tracking, we adopt a multi-stage tracking mode. We applied the proposed algorithm in the implementation of WCDMA base station modem successfully.