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 Degenerated-Inverse-Matrix-Based Channel Estimation for OFDM Systems | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2009 Article ID 807549 10 pages doi 2009 807549 Research Article Degenerated-Inverse-Matrix-Based Channel Estimation for OFDM Systems Makoto Yoshida Fujitsu Laboratories Limited YRP R D Center 5-5 Hikari-no-Oka Yokosuka 239-0847 Japan Correspondence should be addressed to Makoto Yoshida mako@ Received 21 January 2009 Accepted 14 April 2009 Recommended by Dmitri Moltchanov This paper addresses time-domain channel estimation for pilot-symbol-aided orthogonal frequency division multiplexing OFDM systems. By using a cyclic sinc-function matrix uniquely determined by Nc transmitted subcarriers the performance of our proposed scheme approaches perfect channel state information CSI within a maximum of dB degradation regardless of the delay spread of the channel Doppler frequency and subcarrier modulation. Furthermore reducing the matrix size by splitting the dispersive channel impulse response into clusters means that the degenerated inverse matrix estimator DIME is feasible for broadband high-quality OFDM transmission systems. In addition to theoretical analysis on normalized mean squared error NMSE performance of DIME computer simulations over realistic nonsample spaced channels also showed that the DIME is robust for intersymbol interference ISI channels and fast time-invariant channels where a minimum mean squared error MMSE estimator does not work well. Copyright 2009 Makoto Yoshida. 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 Orthogonal frequency division multiplexing OFDM is well known as an anti-multipath-fading technique for broadband wireless systems and is used as a standard in digital broadcasting and wireless LAN systems. Increased demand for a better .