tailieunhanh - Báo cáo hóa học: "Channel length assisted symbol synchronization for OFDM systems in multipath fading channels"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Channel length assisted symbol synchronization for OFDM systems in multipath fading channels | Chin EURASIP Journal on Wireless Communications and Networking 2011 2011 68 http content 2011 1 68 o EURASIP Journal on Wireless Communications and Networking a SpringerOpen Journal RESEARCH Open Access Channel length assisted symbol synchronization for OFDM systems in multipath fading channels Wen-Long Chin Abstract Despite the promising role of orthogonal frequency-division multiplexing OFDM technology in communication systems its synchronization in multipath fading channels remains an important and challenging issue. This work describes a novel synchronization algorithm that exploits channel length information for use in OFDM systems. A timing function that can identify the ISI-free region and subsequently the channel length is also developed based on both the redundancy of the cyclic prefix CP and the drastic increase in intersymbol interference ISI that rises with symbol timing error in multipath fading channels. Knowledge of the channel length information allows the symbol timing to be safely set in the middle of the ISI-free region without any ISI. Simulation results indicate that the maximum value of the timing function occurs at the correct timing offset when the signal-to-noise ratio SNR is high. From low- to medium SNRs the correct timing offset is guaranteed when the signal power induced by the channel tap is more significant than the noise power. Furthermore an efficient search algorithm is derived to reduce the search complexity search time and computation complexity . Keywords Channel length Cyclic prefix CP Orthogonal frequency-division multiplexing OFDM Symbol synchronization I Introduction Orthogonal frequency-division multiplexing OFDM is a promising technology for broadband transmission. However OFDM systems are sensitive to synchronization errors that may destroy the orthogonality among all sub-carriers. Accordingly intercarrier interference ICI and intersymbol interference ISI are introduced by synchronization errors .