무선통신 채널에서 다이버시티 기법과 채널 부호와 기법을 사용한 DS/CDMA 시스템의 블록 오율 성능개선

강희조 東新大學校 工業技術硏究所 2001 工業技術硏究 Vol.7 No.-

In this paper, we analyze the error performance improvement of the CDMA system, whose information data are spread with PN sequences, and the chip signals are modulated with BPSK signal, combining MRC diversity technique with repetition transmission, or FEC code in mobile communication channel which is characterized by Nakagami fading. As a result of study, the coding techniques provide more efficient improvement than a diversity technique, but coding techniques are required the adding bandwidth as many coding rate. Also, when the system is combined MRC diversity technique with coding techniques, the amount of improvement is dramatically increased.

이동체 통신에 있어서 멀티슬롯 할당을 이용한 적응변조방식에 관한 성능해석

강희조 東新大學校 1998 論文集 Vol.10 No.-

This paper proposes an adaptive multislot allocation algorithm in order to achieve larger system capacity and higher throughput data transmissions. The proposed system is the combination of the slow adaptive modulation system, in which the base station dynamically assigns optimum modulation parameters measuring the C/N (carri-to-noise power ratio) of each transmission terminal, and the multislot allocation scheme, in which the base station flexibly allocates an appropriate number of TDMA data slots according to the instantaneous load conditions. Computer simulations confirm that the proposed system can tremendously improve average message delay characteristics in comparison with the conventional fixed slot allocation method.

적응변조방식을 이용한 멀티미디어 통신 시스템에 있어서 동적채널 할당 방식에 관한 성능

강희조 東新大學校 工業技術硏究所 2000 工業技術硏究 Vol.6 No.-

This paper proposes a adaptive modulation with dynamic assignment (AMDCA) to achieve high capacity, high speed, high quality mobile communication systems. In the proposed method, the received C /(N + I) of each TDMA slots is measured to search available slot as to find out the optimum modulation parameters for each slot, thereby effectively combines the buffering effect of spacially distributed electric field strength by the adaptive modulation and that of spacially and temporary distributed traffic by the DCA. Computer simulation confirms the proposed system can achieve 7.5 times larger capacity than the conventional fixed assignment system using QPSK in the case of the voice transmission.

위상에러와 라이시안 페이딩을 고려한 DS/CDMA 시스템의 성능평가

강희조 東新大學校 工業技術硏究所 1998 工業技術硏究 Vol.4 No.-

In this paper, the performance improvement of DS-CDMA (Direct Sequence-Code Division Multiple Access) systems have been analyzed in land mobile satellite communication and Rician fading channel. Also, the performance improvement scheme have been studied and results are obtained for DS-CDMA system. The results show that the error performance of the DS-CDMA system is degraded by MAI (Multi Access Interference) and multi path fading. In this case, performance improvement has been obtained by adopting CCI (Co-Channel Interference) cancellation techniques. The analysis model selected communication using a low earth orbit mobile satellite. The Doppler phase error due to the relative velocity between the earth station and a satellite in communications using a low earth orbit mobile satellite is detected. The error performance of DS-CDMA system by using CCI canceller in the presence of the MAI, Rician fading channel environment with the Doppler phase error and AWGN(Additive White Gaussian Noise) was compared with the error performance without CCI canceller.

나카가미 페이딩과 라이시안 페이딩 환경하에서의 다이버시티 수신된 DS-CDMA/디지틀 신호의 성능 분석

강희조,이정도 東新大學校 工業技術硏究所 1997 工業技術硏究 Vol.3 No.-

본 논문에서는 대역확산 방식인 DS-CDMA/MFSK, MPSK, MDPSK 신호를 m-분포 페이딩과 라이시안 환경하에서 유도한 후, 페이딩으로 인한 경감된 오율성능을 개선하기 위해 MRC(Maximal Ratio Combining) 다이버시티 기법을 사용하여 두 환경에서 비효 분석하였다. 라이시안 페이딩 모델은 m-분포 페이딩 모델에 알맞은 값을 선택하여, 사용자 수( U), 페이딩 지수(m), 라이시안 지수(K), 다이버시티 가짓수( L), 그리고 비트에너지 대 잡음전력비(E_(b)/(N_(o))를 함수로 하여 오율 특성을 구했다. 그 결과 페이딩이 약할수록, 사용자 수와 다이버시티 가짓수가 많을수록 결과는 점점 더 일치함을 알 수 있었다. The error rate equation of DS-CDMA/MFSK, MPSK, MDPSK signal has been derived in m-distribution and Rician fading channels. MRC(Maximal Ratio Combining) diversity technique in conjunction is employed for improving the bit error rate performance which is degraded by multipath fading. The suitability of modeling a Rician fading environment by a properly chosen m-distribution model is examined. Using the error performance of the derived equation has been evaluated and shown in figures as a function of user number ( U), fading index (m), Rician factor (K), diversity branches number (L) and E_(b)/N_(o). The results shows that the error performance corresponds as much as fading becomes weak and increases with user number ( U) and diversity number (L).

이동통신 채널에서 Truncated Type-Ⅱ Hybrid ARQ 기법과 MRC 다이버시티 기법에 의한 Hybrid DS/SFH-CDMA/FSK 신호의 성능 개선

강희조,임태길 東新大學校 工業技術硏究所 1997 工業技術硏究 Vol.3 No.-

본 논문에서는 AWGN, MUI, 나카가미 페이딩이 존재하는 육상 이동통신 채널에서 Truncated Type-Ⅱ Hybrid ARQ 기법과 MRC 다이버시티 기법에 의한 Hybrid DS/SFH- CDMA/FSK 신호의 성능을 분석하였다. 또한 에러율과 throughput에 대한 결과를 그림에서 보여주고 있다. 결과적으로 가장 중요한 것은 본 논문에서 Truncated Type-Ⅱ Hybrid ARQ 기법을 채용했을 경우에 MRC 다이버시티 기법이 결합되었을 때 그 개선 효과가 증가하고, FEC 기법을 채용할 경우 보다 더 효율적으로 개선되므로 고신뢰도와 지연이 제한되는 응용 프로그램을 필요로 하는 이동통신 시스템 및 무선 데이터 통신 시스템에 적용할 수 있다. In this paper, we analyze the performance of the Hybrid DS/SFH-CDMA/FSK signal with truncated Type-Ⅱ Hybrid ARQ and MRC diversity techniques in mobile communication channel which is characterized by AWGN, MUI (Multi-User Interference) and Nakagami fading. Using the derived equation, the error probability and the throughput are evaluated and shown in figures. The most important results that we have obtained in this paper are that the truncated Type-Ⅱ Hybrid ARQ scheme provides more efficient improvement over on FEC (Forward Error Correction) scheme and the amount of improvement is increased when it is combined with MRC diversity technique. Therefore, it is proper for mobile and radio data communication systems that require high reliability and delay-limited applications.

라이시안 페이딩 환경하에서 이동위성 통신채널상에서 도플러 효과에 의한 DS/CDMA-PSK 신호의 오율성능

강희조,이권현 동신대학교 환경연구소 1997 환경연구 Vol.2 No.1

본 논문에서는 육상 이동 통신채널과 저궤도 (LEO : Low Earth Orbit) 이동위성통신에 적용할 수 있는 라이시안 페이딩 환경에서 도플러 위상에러와 다중접속 간섭이 동시에 부가될 경우 DS/CDMA-PSK신호의 성능 분석을 하였다. 성능평가는 신호전력 대 잡음전력비(SNR), 도플러위상에러(dp), 라이시안 페이딩 지수(K), 다중접속 사용자 간섭수(U), 그리고 확산 코드길이(N)에 따른 분석을 한다. 성능 분석 결과 라이시안 페이딩 지수와 화산 코드의 길이가 증가함에 따라 성능이 좋으며, 도플러 위상 에러와 다중접속 사용자수가 증가하면 성능이 열화 됨을 알 수 있었다. In this paper, It was studied on the performance of DS/CDMA-PSK signal over land mobile satellite communication channel. The analysis model selected communication using a low earth orbit mobile satellite. The Doppler phase error due to the relative velocity between the earth station and a satellite in communications using a low earth orbit mobile satellite is detected. As for the doppler phase error and the direct wave to reflex wave ratio and the MAI(Multi Access Interference) user number and the PN code length, the performance of DS/CDMA-PSK signal in the presence of the Rician fading channel environment with the Doppler phase error and noise was compared with the error performance.

이동통신에서 MRC 다이버시티 수신시 BCH 부호화된 M-ary FSK 신호의 성능해석

姜熙照,金在玟 東新大學校 工業技術硏究所 1994 工業技術硏究 Vol.1 No.-

The error rate performance of NFSK(Noncoherent Frequency Shift Keying) signal transmitted through the Gaussian noise and Nakagami fading channel has been analyzed. In this paper as diversity technique MRC(Maximal Ratio Combining) diversity and coding techniques BCH(Bose-Chaudhuri-Hocquenghem) code is adopted. The amount of improvement of the error performance has been evaluated as function of fading figure, error-correcting capability and diversity branch number. And the results are shown in graphs and discussed. From the results, it is known the error performance of NFSK signal improves by adopting coding techniques even in fading environment and with the diversity technique and coding techniques is very effetive e.g., at 10^(-3) in error rate, with the diversity technique and BCH(15, 7) coded is better than with the diversity and BCH(15, 7) coded NFSK signal by amount of 5(dB) in terms of E_(b)/N_(o), respectively.

제주 동부지역 지하수 인공함량에 관한 연구

윤정수,신희섭,박상운 濟州大學校 基礎科學硏究所 1996 基礎科學硏究 Vol.9 No.2

The purpose of this study is to examine the comprohensive field test of the artificial groundwater inflow method where the east confined aquilfer selected for study that was badly degraded by sea water. The stream order of Cheunmichen has the 6th order whereas Kamachen is the 4th order. The bifurcation ratio is 2.50 in the Gheunmi stream and 2.42 in the Kama stream, which indicates that the studied stream is flows steeper slope region and belong to the short period of erosional streams. Average annual precipitaion is 2.024.9mm. Total precipitation in 4 months from June to September amounts to 48% out of annual precipitation and them run off the stream flows. Evapotranspiration is about 750.2mm, estimating the run-off of the surface is about 318.8mm and total amount of the recharge to aquifer is 956.4mm/yr. when precipitation is about 312mm from July first to third in 1995 in study area. The surface run-off of cheunmichen were calculated as about 10825.790㎥/24hr, and the total amount of inflow from the 4 recharge wells to aquifer is about 55.468㎥/24hr., when precipitation is about 312mm from July first to third in 1995 in study area. Injection was begin in 4 wells from July second to third in 1995, the groundwater levels for observatory A well is increase to 0.418m, 0.109m respectively rather than that the original levels. The purpose of this study is to examine the comprehensive field test of the artificial groundwater inflow method where the east confined aquilfer selected for study that was badly degraded by sea water. The stream order of Cheunmichen has the 6th order whereas Kamachen is the 4th order. The bifurcation ratio is 2.50 in the Gheunmi stream and 2.42 in the Kama stream, which indicates that the studied stream is flows steeper slope region and belong to the short period of erosional streams. Average annual precipitaion is 2.024.9mm. Total precipitation in 4 months from June to September amounts to 48% out of annual precipitation and them run off the stream flows. Evapotranspiration is about 750.2mm, estimating the run-off of the surface is about 318.8mm and total amount of the recharge to aquifer is 956.4mm/yr. in 1995 in study area. The surface run-off of cheunmichen were calculated as about 10825.790㎥/24hr, and the total amount of inflow from the 4 recharge wells to aquifer is about 55.468㎥/24hr.,when precipitation is about 312mm from July first to third in 1995 in study area. Injection was begin in 4 wells from July second to third in 1995, the groundwater levels for observatory A well is increase to 0.418m, 0.109m respectively rather than that the original levels.

제주도 해안선주변 1개정점(용두암 근처)에서 부유성갑각류 현존량의 일주변화

고유봉,신희섭,정용진 제주대학교 해양연구소 1989 해양자원연구소연구보고 Vol.13 No.-

Planktonic crustacean samples and hydrographic data were obtained seasonally at intervals of two hours for one day at one station(near the Dragon Head Rock) around the coast line of northern part in Cheju Island from 1987 to 1988. Seasonal average individuals were low in February (307 indv./㎥) and October (282 indv./㎥), and highest in August (3.459 indv./㎥). Most of individuals were small animals retained on fine mesh(90μm mesh) net, composing over 91% of the total crustaceans. Range of seasonal average biomass was 3.0~20.5㎎/㎥. Generally, individuals and biomass of small planktonic crustaceans were higher during the daytime than those at night. whereas those on medium or large organisms were remarkably higher during the nighttime, Daily mean production, and ratio of daily production to biomass(P/B ratio) were highest in August and lowest in February, showing the larger the number of individuals and water temperature. the greater daily production and P/B ratio.