Research On Channel Estimation Based On Block Pilot In FBMC System

Faced with the high user experience rate,low end-to-end delay,and huge number of user connections in the future communication network,the Orthogonal Frequency Division Multiplexing(OFDM)used in 4G is no longer sufficient to support,due to its low spectrum resource utilization,large side lobes,and high out-of-band leakage.Among the most popular multi-carrier schemes,the Filter Bank Multi-carrier(FBMC)has strong anti-inter-carrier interference and inter-symbol interference due to the use of a prototype filter with good time-frequency focusing characteristics,and with the ability of low leakage and high spectrum utilization,has become the most powerful candidate for multi-carrier technology in wireless communication in the future.However,the above advantages of FBMC system are due to the relaxation of orthogonal conditions which only satisfied in the real domain,so there is inherent imaginary interference,which leads to the channel estimation technique used in the traditional OFDM system cannot be directly applied to the channel estimation of FBMC system.In this paper,the channel estimation algorithm based on block pilot in FBMC system is studied,and some improved channel estimation algorithms are proposed.The specific contributions are as follows:(1)An improved channel estimation algorithm based on block pilot in FBMC system is proposed.The paper studies the pilot-based channel estimation method,include interference approximation algorithm,interference cancellation algorithm and interference avoidance algorithm.The interference approximation algorithm uses the interference information to form an equivalent pilot,and the performance of the channel estimation can be improved by increasing the power of the equivalent pilot.Most of the current IAM algorithms use a three-column pilot structure,which is a waste of spectrum resource.For this problem,an improved method is proposed.First,a new twocolumn pilot structure is designed.Then,from the calculation expression of the channel frequency response value,it is found that the influence of noise can be further reduced by introducing the idea of wavelet denoising.The simulation results show that the new channel estimation algorithm not only maintains the performance but also improves the transmission efficiency because of saving a list of pilot overhead.(2)An improved channel estimation algorithm based on subcarrier weighted in FBMC system is proposed.At present,among the channel estimation algorithms basedon pilot in FBMC system,the research based on block pilot is the most,and the strong correlation between the subcarriers of the block pilot makes the redundant information exist in the channel estimation result.There are relatively few studies on algorithms that utilize redundant information.In order to improve the accuracy of the channel frequency response estimation,based on the OQAM-C algorithm with the idea of interference elimination,this paper adopts the same pilot structure of OQAM-C,then,carry out weighted processing on the sub-carrier estimation value,and the redundant information is used to improve the performance of channel estimation.Simulation results show that the new algorithm effectively improves the performance of channel estimation.