π/4 shift DQPSK 직교 다중 캐리어 변조/차동검파 시스템의 성능 분석 = Performance Analysis of π/4 shift DQPSK-Orthogonal MultiCarrier Modulation/Differential Detection System

다국어 초록 (Multilingual Abstract)

This paper describes a noncoherent demodulation of orthogonal frequency division multiplex(OFDM) signals making use of π/4 shift DQPSK. The performance of the system with and without the guard interval and the convolutional code is analyzed by computer simulations on additive white gaussian noise(AWGN) and frequency selective channels under static and mobile reception conditions, The result of the research shows that the use of the guard interval for reducing ISI can provide performance improvement of 1dB to 4 dB under the frequency selective fixed and portable channels, And the use of the guard interval and the convolutional code can avoid the error floor for the frequency selective mobile channel.