The Study Of Channel Equlization At High-speed Mobile Environment

Orthogonal frequency division multiplexing (OFDM) technology has become the coretechnology of the high speed wireless communication. In the decline of the channel characteristics,multipath fading and Doppler frequency shift have the greatest impact on the broadband wirelessmobile business, and the influence that the two factors have on the OFDM systems is the current hotspot of research.Under the long multipath condition, this thesis proposes a frequency algorithm based on thebalance of frequency domain. The balanced performance of this algorithm is obviously superior tothe traditional equalization algorithm. As to the fast time-varying channel, this thesis puts forwardtwo joint equalization algorithms which are based on parallel interference eliminate and serialinterference eliminate. The constraints of the two algorithms are less than the traditional methods.Under the time-varying conditions, the algorithm based on parallel interference can effectivelyeliminate the Inter Carrier Interference (ICI), and the accuracy of the data judgment and channelestimation will be higher too. During improving large quantities of the former algorithm, the thesisalso proposes the method based on serial interference eliminate, because this algorithm avoids thecomplex matrix for inverse, amount of calculation is reduced significantly, and the practicalapplication is relatively simple.In the high-speed mobile environment, ICI will seriously affect the performance of the OFDMsystem. This thesis analyzes the formation of ICI and proposes an improved algorithm to eliminateICI, which can raise the efficiency of bandwidth, however the Bit Error Rate (BER) of the systemdrops. Finally, in the rapidly changing channel's premise condition, a new method which recoverssignal through received symbol is proposed. At first, this thesis analyzes the efficiency of thealgorithm under time-varying channel, and gives equilibrium results in Jakes spectrum Rayleighfading channel. In this method, there is no limit for changes of the linear channel, and it also hasgood robustness for the pace of change in the channel. However, the weakness is that when thechannel mismatch, performance will have to decline significantly．...