• The Journal of the Acoustical Society of Korea
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• v.19 no.4
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• pp.52-57
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• 2000

In this paper, we designed the 16 Kbps speech coder that has compatibility with CS-ACELP algorithm(G.729). The speech signal is sampled at rate of 16 KHz, divided into two narrowband signal by QMF filterbank, and decimated to rate of 8 KHz. The lower-band signal is encoded by CS-ACELP and the upper-band signal is encoded by Adaptive Transform Coding(ATC) algorithm. At the receiver, two band signals are synthesized by decoder of CS-ACELP and ATC, respectively. The reconstructed output is obtained by passing the QMF synthesis bank. The proposed wideband coder is evaluated with ITU-T G.722 coder through the Mean Opinion Score(MOS) test.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.447-450
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• 2009

In this paper, binary pulse-antipodal modulation (2PAM) direct-sequence (DS) ultra-wideband (UWB) system is applied to multiple input multiple output (MIMO) system using vertical bell lab layered space-time (V-BLAST) structure to achieve high-data-rate communications over indoor wireless channels. The relationship between antenna dimension and BER performance of 2PAM DS UWB MIMO system is discussed. In the receiver of UWB-MIMO system, various MIMO detection algorithms such as zero-forcing (ZF), ZF-ordered successive interference cancellation (OSIC), minimum-mean-square-error (MMSE), MMSE-OSIC and maximum likelihood (ML) are comparatively studied.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.33-36
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• 2000

In this paper, the performance of the W-CDMA system with smart antenna is investigated. The channel is assumed as wideband realistic channel mode, JTC(Joint Technique Committee), which has clustered multipaths. The beamforming-RAKE receiver structure is proposed, whose performance is analyzed on the assumption of the perfect channel estimation. In a simulation, the probability density function(pdf) of SINR(Signal to Interference and Noise Ratio) according to the number of antennas and users is presented. And based on the pdf of SINR, the BER(Bit Error Rate) is presented. According to the result of a simulation, the performance of the W-CDMA system with smart antenna over the realistic JTC channel model has been considerably improved.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.2
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• pp.217-226
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• 2001

A small sized ceramic dielectric patch antenna is designed and implemented for GPS/GLONASS combined receiver, and it shows a wideband characteristics with circular polarization. For the miniaturization of the antenna, high-permittivity dielectric material is used, and the wideband characteristics with low axial-ratio is achieved by using dual feed with 90$^{\circ}$ phase difference. The measured data of the manufactured antenna show that the bandwidth is 242 MHz, the axial ratio is less than 3 dB, the half-power beam-width is more than 112$^{\circ}$, and the antenna satisfies the required characteristics of the GPS/GLONASS antenna.

• ETRI Journal
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• v.36 no.3
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• pp.460-468
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• 2014

This paper addresses the problem of joint time of arrival (TOA) and direction of arrival (DOA) estimation in impulse radio ultra-wideband systems with a two-antenna receiver and links the joint estimation of TOA and DOA to the sparse representation framework. Exploiting this link, an orthogonal matching pursuit algorithm is used for TOA estimation in the two antennas, and then the DOA parameters are estimated via the difference in the TOAs between the two antennas. The proposed algorithm can work well with a single measurement vector and can pair TOA and DOA parameters. Furthermore, it has better parameter-estimation performance than traditional propagator methods, such as, estimation of signal parameters via rotational invariance techniques algorithms matrix pencil algorithms, and other new joint-estimation schemes, with one single snapshot. The simulation results verify the usefulness of the proposed algorithm.

• Journal of information and communication convergence engineering
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• v.2 no.4
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• pp.205-208
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• 2004

In this paper, we analyzed the performance of SDR-based dual-band CDMA system in wideband multipath channel employing RAKE receiver with MRC diversity. For the simulation of SDR-based dual-band CDMA system, we used digital IF techniques, polyphase analysis filter bank as channelizer. Also, Remez exchange algorithm is employed in the realization of the digital filter in the polyphase analysis filter bank. For performance analysis of dual-band CDMA system, we consider power loss of IF signal after passing through channel and the filter. Also, the performance for different sampling rates is analyzed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6A
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• pp.767-774
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• 1999

In this paper, we compare the performance of asynchronous W-CDMA system with different bandwidth. We take into consideration of wideband multipath channel environment which consists of discrete multipath components whose strength is Rayleigh distributed. Each CDMA system different bandwidth experience different effects of multipath because there are different number of multipath within one chip duration according to the spreading bandwidth. We derive the average error probability versus the capacity, and compare the capacity of W-CDMA systems using the RAKE receiver with EGC diversity.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.309-310
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• 2008

In this paper, we propose a novel D-ATR (Differential-Average Transmitted Reference) scheme for UWB (Ultra Wide Band) based on impulse radio. The proposed scheme utilizing differential coding at transceiver, does not cause half loss of data rate unlike the conventional TR (Transmitted Reference) and ATR (Average TR) systems which transmit additional reference signals. In addition, the proposed scheme may provide improved BER (Bit Error Rate) performance by averaging the received reference signals like the conventional ATR. The proposed D-ATR receiver produces the averaged reference template by considering both the detected data bit and the differential coding rule.

• ETRI Journal
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• v.28 no.1
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• pp.95-98
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• 2006

In this letter, a novel M-ary code-selected direct sequence (DS) ultra-wideband (UWB) communication system is presented. Our purpose is to achieve a high data rate by an M-ary code-selected direct sequence bipolar pulse amplitude modulation (MCSDS-BPAM) scheme. In this system, a particular DS code sequence is selected by the $log_2M$/2 bits from the DS gold code set. This scheme can accomplish both a high data rate without increasing the system bandwidth or changing the pulse shape and improve the BER with an increase of modulation level M even at a lower signal-to-noise ratio (SNR). The receiver signal processing algorithm is given for an MCSDS-BPAM UWB system over an ideal AWGN channel and correlation receivers.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.313-317
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• 2003

In this paper, ultra-wideband frequency synthesizer which operates at S-band ($2{\sim}4GHz$) is designed. Designed frequency synthesizer shows the frequency range of $2.2{\sim}4.0GHz$ and output power of $-2{\sim}3dBm$. Phase noise characteristics are measured below -92.0dBc/hz at 100kHz offset frequency in entire sweep range and lock time is measured below 3.55ms. Spurious level is below -62.33dBc at comparison frequency of 1MHz.