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陳年鋼,方成日,卓龍相 단국대학교 1995 論文集 Vol.29 No.-
Fading simulator which simulates environments of real mobile communication channels was developed to find fading compensation method and measure system performance. In this paper, designed and implemented the device that can be simulated multipath fading situation in the land mobile communications. A realistic PDF(probability density function) of vertical spatial angle was introduced to Aulin's 3 Dimentional model, and induced fading control signals. The result control signals are useful to apply general purpose micro-processor and look up table method. Therefore, it is possible to design fading simulator that has comparatively accurate property using simple hardware. In order to estimate the performance of implemented simulator, simulation results were compared with criteria which is provided by the U. S. EIA/TIA document TR 45.3(IS-55). CDF(cumulative distribution function) measurements to overall Doppler frequencies range indicate good agreement with criterion. But LCR(level crossing rate) makes the serious false detection error problem by granular noise. Because it is the function on time. Accordingly, the exact LCR measurement was very difficult, but the results indicated comparatively good agreements with the theorical values.
디지탈 이동통신용 TCM-MPSK의 필터 특성에 관한 연구
陳年鋼,方成日,李承大 단국대학교 1992 論文集 Vol.26 No.-
In this paper, TCM-MPSK for land mobile radio has been simulated to calculate the spectrum efficiency, η_T, in terms of multi-level phase modulation, coding rate of FEC, and fading rate. The calculated results show that TCM-QPSK can make its efficiency higher than other system(M=2, 8, 16) regardless of the diversity. A switched-capacitor filter for limiting the channel bandwidth is used to improve intersymbol interference(ISI) and jitter in trellis-coded M-ary PSK systems. It is difficult to analyze their effects of the system mathmatically. Therefore, their effects are measured using eye diagrams to results in improving by -3.25 dB and 67.9% switched-capacitor characteristics having roll-off factor, △0.3, and a=7.5% above the Nyquist rate more than the case with only △=0.3 in case of trellis-coded 8-PSK system.
W-CDMA를 이용한 PCS 기지국용 RF 송신부의 설계 및 구현
진년강,백주기 단국대학교 1999 論文集 Vol.34 No.-
In this study, the wideband CDMA transmitter for PCS is designed and implemented. As a modulation method, the CC-OQPSK implemented as the ASIC and this modulation method has better spectral and power efficiency than conventional QPSK system because it has constant envelope characteristics. In the intermediate frequency stage using double-conversion scheme, good hamonics rejection characterisitics and gain of 20 ㏈ were obtained. The output power of two-stage RF amplifier is +21.14 ㏈m in 1.9㎓ band. It has been confirmed that the electrical characterisitics of the transmitter which is implemented in the paper satisfy with the specification of wideband CDMA transmitter that has been set to be the design standard of PCS.
이동무선채널에서 1-비트 차동검파를 갖는 CPM의 성능 향상
陳年鋼,方成日,姜洪求 단국대학교 1993 論文集 Vol.27 No.-
In this paper, the performance of constant envelope digital CPM with 1-bit differential detection has been analyzed in time selective fading AWGN channels. The analysis is based upon the canonic receiver model combining postdetection for performance enhancement. In radio mobile communication channel with AWGN and fading, it is shown that the diversity receiver is effective in decreasing influence of the AWGN and the fading. Among the CPM schemes, the performance of 2SRC is found to be the best. The 3RC and GMSK(B_iT=0.25) performances are quite close and 2RC and 2SRC performances are quite close.
金允溟,陳年鋼,朴東明 단국대학교 1987 論文集 Vol.21 No.-
This paper represents a graphical design techniques of the symmetrical dielectric waveguide couplers. Ones the phase constants are found by an approximate modal analysis, coupling lengths can be easily calculated for each couplers. This method will be a convenient approach to the designing of dielectric waveguide couplers.