Research On The Algorithm Of Channel Estimation In LTE-A System With Inter-cell Interference

In the wireless communication system,the performance of the communication system depends largely on the accuracy of the channel estimation.Only when the accurate channel state information is obtained the demodulation signal can be demodulated correctly at the receiver.With the development of wireless communication technology,the frequency domain resources become more and more tense.In order to improve the spectral efficiency and transmission rate,LTE-A(LTE-Advanced)system uses the same frequency network mode,which makes the cell edge users subject to strong interference with the same frequency,seriously affecting the performance of the channel estimation.For the inter-cell interference environment,the traditional channel estimation algorithm needs to be improved to reduce the influence of the co-channel interference.Therefore,it is of great practical significance to study the channel estimation algorithm in the inter-cell interference environment in LTE-A system.Before researching the channel estimation algorithms,this thesis first introduces the development of wireless communication,LTE-A system and its key technologies.The fading characteristics of wireless channel and the channel model commonly used in LTE-A are studied.Then the channel estimation algorithm under the single cell scene is analyzed,including the least squares(LS)channel estimation algorithm,constant copy algorithm,linear interpolation algorithm,DFT-based interpolation algorithm and LMMSE interpolation algorithm.The traditional LMMSE interpolation algorithm assumes that the terminal knows the channel power delay profile(PDP),which is not consistent with the actual situation.This thesis proposes an improved LMMSE interpolation algorithm based on PDP estimation.The algorithm estimates PDP,which is more suitable for practical application in the case of guaranteed performance.In the inter-cell interference environment,the traditional LS algorithm treats the interference signals as additive white Gaussian noise,resulting in a larger channel estimation error.Considering the inter-cell co-channel interference,this thesis proposes an improved joint least squares channel estimation(JLSCE)algorithm,which combines the reference signals of the serving cell and the interfering cells to estimate the channel,which can effectively reduce the impact of inter-cell co-channel interference to get a more accurate channel estimation.In order to further improve the accuracy of channel estimation,this thesis proposes an improved interference rejection combining algorithm based on sequencing interference cancellation.Combining the interference rejection combining algorithm with the channel estimation technique,an iterative channel estimation algorithm based on interference rejection combining is proposed,the algorithm uses the performance gain of interference rejection combining and symbol reconstruction to update the channel initial estimation to obtain more accurate channel estimation.Finally,through the construction of LTE-A simulation link,the proposed algorithm is simulated and conclusions are drawed.