장원호 Won Ho Jang , 홍주석 Ju Seok Hong , 이윤현 Yun Hyun Lee

DOI: JANT Vol.6(No.4) 273-278, 2002

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In this paper, we provide the Interference Canceller Systems(ICS) in the wireless environments in the presence of co-existing ETACS and CDMA digital cellular systems to effectively cancel the interference than the established canceller systems. We proved the enhanced cancelling performances more than 29 dB cancellation characteristics between co-existing ETACS and CDMA digital cellular systems and the stabilized system characteristics in the rapidly changing wireless circumstances.

한용인 Yong In Han , 조치성 Chi Sung Jo , 김인석 Ihn Seok Kim

DOI: JANT Vol.6(No.4) 279-290, 2002

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In this paper, tapered shape of multiport power divider/combiner modified for 2 GHz range from the model published by [10] is proposed. Parameters determining electrical property of the circuit structure have been analyzed by HFSS simulation. For input matching, balance of output signals and phase linearity at each output port, one circular hole has been etched out on the circuit surface. 1:2 and 1:3 power dividers/combiners designed by this study have been compared with the same circuits designed by the method of [10] in terms of S-parameters. As a result, it has been found that the modified structure of power divider/combiner have improved return loss more than 20 dB and another 18 dB, respectively, at 2 GHz.

이남경 Nam Kyung Lee , 채수환 Soo Hoan Chae

DOI: JANT Vol.6(No.4) 290-295, 2002

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In Mpeg-4 system, objects are composed of ES(Elementary Stream). Each of the objects is managed independently by object-based coding and is transmitted via DMIF(Delivery Multimedia Integration Framework). The data streams im Mpeg-4 are transmitted with using DVB-Data Carousel which can improve the reliability and efficiency by cyclic retransmission. This paper describes a system which transmits some part of data stream of Mpeg-4 object with using DVB-Data Carousel to clients via satellite. This also uses a performance enhancing proxy server for reducing round trip time between ground network and satellite.

윤여송 Yeo Song Yun , 김학선 Hak Sun Kim

DOI: JANT Vol.6(No.4) 296-305, 2002

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This paper suggests the parameters of the requirement conditions of minimum performance for a RF transceiver system design from the specifications of IEEE Std 802.11b and IEEE Std 802.11a. It has yielded the requirement conditions of minimum performance in the design process due to these parameters. A RF transceiver system is simulated by using Agilent ADS(Advanced Design System) after selecting the components of optimal conditions to fabricate the RF transceiver system. The results of both the analysis and the simulation will be used for a real wireless LAN design.

박기식 Ki Sik Park

DOI: JANT Vol.6(No.4) 306-311, 2002

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In this paper, we have proposed the Multi-Carrier (MC) CDMA system by adopting multi-interference cancellation techniques connecting an adaptive array antenna and a CCI canceller in cascade form. And, we have analyzed the BER performance of system in AWGN channel where MUI is a major interference degrading the performance of the proposed MC CDMA system. As the result of analysis, a CCI canceller is better efficient than an adaptive array antenna in the performance improvement and that the performance improvement becomes large as the number of users increases when multi-interference cancellation techniques are used in cascade form. Also, we found that performance of 10^5 in a point of view BER could be achieved when E_b/N_o is more than 10 dB.

한석균 Sok Kyun Han , 최병하 Byung Ha Choi

DOI: JANT Vol.6(No.4) 312-318, 2002

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This paper presents a graphical design method for a low noise amplifier using the match circles plotted in the Γ_(IN) plane on the smith chart. Each circle would be useful for reducing some trial and error efforts resulting from making a trade-off for an optimized performance of a single stage amplifier. A design example is presented to illustrate the design procedure.

이양선 Yang Sun Lee , 강희조 Heau Jo Kang

DOI: JANT Vol.6(No.4) 318-325, 2002

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In this paper, the effects of the interference environments on the performance of the time hopping(TH) binary PPM impulse radio(IR) system are presented. Based on the monocycle pulse available within the frequency of 3.1 ~ 10.6 GHz permitted for application by FCC, a PPM-modulated TH IR system simulator was designed and followed by the analysis of the monocycle pulse characteristics as well as the system performance. Particularly for the evaluation of the system performance, the multiple access interference and the narrowband system interference signals were considered as the interference signals. Since the narrowband system interference signal has very narrow bandwidth and very large amplitude compared with those of IR system, the analysis of the IR system performance was implemented by considering the interference power and band fraction ratio of the narrowband interference signal.