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: Research Article Time and Frequency Synchronisation in 4G OFDM Systems | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2009 Article ID 641292 9 pages doi 2009 641292 Research Article Time and Frequency Synchronisation in 4G OFDM Systems Adrian Langowski Chair of Wireless Communications Poznan University of Technology Polanka 3A 61-131 Poznan Poland Correspondence should be addressed to Adrian Langowski alangows@ Received 30 June 2008 Revised 28 October 2008 Accepted 20 December 2008 Recommended by Erchin Serpedin This paper presents a complete synchronisation scheme of a baseband OFDM receiver for the currently designed 4G mobile communication system. Since the OFDM transmission is vulnerable to time and frequency offsets accurate estimation of these parameters is one of the most important tasks of the OFDM receiver. In this paper the design of a single OFDM synchronisation pilot symbol is introduced. The pilot is used for coarse timing offset and fractional frequency offset estimation. However it can be applied for fine timing synchronisation and integer frequency offset estimation algorithms as well. A new timing metric that improves the performance of the coarse timing synchronisation is presented. Time domain synchronisation is completed after receiving this single OFDM pilot symbol. During the tracking phase carrier frequency and sampling frequency offsets are tracked and corrected by means of the nondata-aided algorithm developed by the author. The proposed concept was tested by means of computer simulations where the OFDM signal was transmitted over a multipath Rayleigh fading channel characterised by the WINNER channel models with Doppler shift and additive white Gaussian noise. Copyright 2009 Adrian Langowski. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. 1. Introduction Due to its many .
