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무선멀티미디어 통신을 위한 Coded-OFDM의 성능해석
김창선,김병주,김재수,변건식 동아대학교 생산기술연구소 2001 生産技術硏究所硏究論文集 Vol.6 No.2
Recent communication system has gotten out of character and voice communication. In order to process real-time moving image and numerous data, high-speed and high-capacity communication systems are required to be developed. OFDM(Orthogonal Frequency Division Multiplex) modulates transmitting data with many carriers in parallel. As a result, high-speed data transmission is carried out and high spectral efficiency is provided by overlapping orthogonal frequencies. Therefore, OFDM is applied to many communication systems. In this paper, according to modulation methods(M-PSK and M-QAM), coded-OFDM wireless communication is simulated. Turbo code is used and two channels(virtual and real channel) are used. Both channels have multipath delay spread, Gaussian noise, and peak power clipping. As a result of the simulation, coding gain is about 3dB and it is proved that M-QAM modulation is better than M-PSK.
부지연 회로를 내장한 200MHz 고속 16M SDRAM
김창선,장성진,김태훈,이재구,박진석,정웅식,전영현 대한전자공학회 1997 電子工學會論文誌, C Vol.c34 No.4
This paper shows a SDRAM opeating in 200MHz clock cycle which it use data interleave and pipelining for high speed operation. We proposed NdC (Negative DEaly circuit) to improve clock to access time(tAC) characteristics, also we proposed low power WL(wordline)driver circit and high efficiency VPP charge-pump circit. Our all circuits has been fabricated using 0.4um CMOS process, and the measured maximum speed is 200Mbytes/s in LvTTL interface.