Adaptive Sc-fde System And Channel Estimation,

OFDM and SC-FDE are two supportive technologies of wideband wireless communications, this thesis mainly introduces adaptive SC-FDE system based on OSS and one of key technologies of adaptive SC-FDE system — channel estimation.This thesis firstly analyzes the characters of wideband wireless channel in brief, and points out that the wideband wireless channel has double selectivity, which are time selectivity and frequency selectivity. Especially under the environment of high speed, how to deal with the time variance of the channel becomes a difficult problem of wireless communication.After simple introduction of the basic principles of OFDM and SC-FDE, this thesis discusses the duality between OFDM and SC-FDE. With this duality, this thesis analyses some problems of OFDM and SC-FDE, and brings some new concepts in SC-FDE system.This thesis analyses the effect of different equalization methods for OFDM and SC-FDE, and introduces the SC-FDE system based on OSS theory (or adaptive SC-FDE system) and Gaussian criterion which is used to decide the dimension of OSS. This system uses those frequency domain sub-channels with higher gain to transmit information and avoids the sub-channels with lower gain. With this method, the performance of SC-FDE is improved obviously. When Gaussian criterion is adopted to determine the dimension of OSS, the performance of SC-FDE over multi-path fading channels is very close to that over AWGN channel. Since some frequency domain sub-channels with very low gain are forbidden, so the system wastes a part of spectrum, the spectral efficiency of adaptive SC-FDE seems to decrease. So this thesis designs some simulations to compare the spectral efficiency of OFDM and SC-FDE. From the simulation results, such conclusions can be drawn: the spectral efficiency of adaptive SC-FDE is much higher than that of coded OFDM, and under the...