Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học Journal of Biology đề tài: Research Article Time-Frequency Based Channel Estimation for High-Mobility OFDM Systems—Part II: Cooperative Relaying Case | Hindawi Publishing Corporation EURASIP Journal on Advances in Signal Processing Volume 2010 Article ID 973286 7 pages doi 2010 973286 Research Article Time-Frequency Based Channel Estimation for High-Mobility OFDM Systems Part II Cooperative Relaying Case Erol Onen Niyazi Odabasioglu and Aydin Akan EURASIP Member Department of Electrical and Electronics Engineering Istanbul University Avcilar 34320 Istanbul Turkey Correspondence should be addressed to Aydin Akan akan@ Received 17 February 2010 Accepted 14 May 2010 Academic Editor Lutfiye Durak Copyright 2010 Erol Onen et al. 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. We consider the estimation of time-varying channels for Cooperative Orthogonal Frequency Division Multiplexing CO-OFDM systems. In the next generation mobile wireless communication systems significant Doppler frequency shifts are expected the channel frequency response to vary in time. A time-invariant channel is assumed during the transmission of a symbol in the previous studies on CO-OFDM systems which is not valid in high mobility cases. Estimation of channel parameters is required at the receiver to improve the performance of the system. We estimate the model parameters of the channel from a time-frequency representation of the received signal. We present two approaches for the CO-OFDM channel estimation problem where in the first approach individual channels are estimated at the relay and destination whereas in the second one the cascaded source-relay-destination channel is estimated at the destination. Simulation results show that the individual channel estimation approach has better performance in terms of MSE and BER however it has higher computational cost compared to the cascaded approach. 1. Introduction In wireless communication antenna diversity is .
