Channel Estimation Scheme For Ofdm Systems

In the future, wideband wireless communication system faces the challenge of the impact of multipath fading channel and system bandwidth efficiency. The OFDM technique can combat effectively the influence of multipath fading channel by converting the frequency-selective multipath fading channel into a number of flat subchannels in the frequency domain. Therefore, OFDM technique for wireless broadband digital communication system has been widespread concern. Accurate channel state information (CSI) guarantees the information to be reliably received for OFDM system. Channel estimation techniques have different effect on synchronization and subcarrier allocation. Thus, accurate estimation of channel state information is one of the key issues for OFDM system.Comprehensive research and analysis is conducted in channel estimation for OFDM systems. Firstly, this paper studies the channel estimation method for OFDM system based on pilot symbol. The pilot insertion method and interpolation algorithms in channel recovery are studied. Then, research on RLS and LMS algorithms were simulated and analyzed although they are based on different criteria of adaptive filtering methods. three interpolation algorithm and two estimate criteria are compared. Finally, this thesis analysises a joint channel estimation method in time and frequency domain. Finally, the LMS estimation algorithm RTL implementation is verified successfully in OFDM systems based on 802.11a.