Research On Channel Estimation Algorithm Of Lte Downlink

Orthogonal Frequency Division Multiplexing(OFDM) is one of the key technology of high data rate wireless transmission application,which is a multi-carrier digital modulation technology. The oscillation of the transmitter and receiver deviation or the doppler effect can cause the frequency offset in mobile OFDM system, what destroys the orthogonality between sub-carrier, then causes inter-carrier interference (ICI), and makes the performance of the system rapidly deteriorating. Therefore, we must suppress ICI interference, and improve the system performance. This thesis is expanded to study the two main factors of the frequency offset and doppler effect, in view of which cause ICI.First, the characteristics of wireless channel is introduced in this thesis, especially expounds the characteristics of small scale fading channel, the basic principle of OFDM is briefly described, and the causes and the effects of ICI are particularly discussed; Secondly, with studied the self-cancellation technology for mitigating ICI, including the coding technique and the scheme design technology, and analyzes the existing several valuable frequency offset estimation algorithm, then an effective new scheme for mitigating ICI is proposed in the article, the simulation results show that the proposed scheme can validly remove the "error floor" in a wide range of frequency offset, and the performance of the elimination algorithm is improved than before since that; Finally, with having further studied the frequency domain equalization algorithm, including the traditional frequency domain equalization algorithm and different types of iterative equalization algorithm, by aiming at the shortcomings about the tall complexity or the poor performance, this paper presents a kind of difference treatment scheme using MMSE equalization for in-band and out-band interference information. Theoretical analysis and simulation results show that:on the one hand, compared with the band equalization algorithm, the performance of the system significantly improve; on the other hand, compared with the traditional full form equalization algorithm especially iterative equalization algorithm, The complexity is similar linear relation with the banded equalization algorithm.