Research On Channel Estimation And Pilot Design In LTE-A System

In the next generation mobile communication system, the data coherent detection and soft decoding need to know the channel coefficients which are given by the channel estimation. The channel estimation accuracy of channel coefficient directly determines the system receiver performance, so the channel estimation and pilot design has been one of the key technologies in the LTE and LTE-A system.This paper studies an improved Jakes channel simulation model and proposes the channel simulation flow chart for LTE. Then a time-frequency two-dimensional channel estimation of LTE system is built and the performances of the different channel estimation algorithms are compared. Futhermore, a novel method for the optimal pilot design is propsed. Firstly, the spacings in the time and frequedncy domain between two pilot symbols are determined according to the largest multi-path delay and the maximum Doppler frequency shift, respectively. Then the exhaustive search method is used to list all possible pilot patterns. Finally, the MSE between the estimated channel and actual channel are calculated in order to obtaining the minimum one which corresponds to the optimal pilot pattern. Simulation results show that the system BER performance of the optimal pilot pattern is better than that of the original one in LTE system and prove the proposed algorithm is correct and efficient.This paper still studies the reference signal design of the normal CP for the LTE-A system. According to the design principles of normal CP, the existing RS patterns of the normal CP are analyzed and the superiority of the existing patterns are verified by simulation assessment. Simulation results show that CDM pattern not only satisfy the compatibility and overhead requires but also can obtain better channel estimation performance.This paper finally the reference signal design of the extended CP for the LTE-A, such as the RS overhead design, DMRS design of Rank 1-2, DMRS design of Rank 3-4, DMRS design of Rank 5-8 and layer mapping analysis. And based on above all, a LTE-Advanced exhaustive reference signal system design is proposed, Simulation results show that the optimal pilot proposed by the new exhaustive design methods can get the best performance.