Research On FBMC Channel Estimation Based On Pilot Design

The fifth generation mobile communication technology(5G)requires the physical layer waveform technology to be more flexible and have higher frequency utilization efficiency.At the same time,the conventional OFDM adds cyclic prefix in order to increase the system's resistance to multipath interference,which results in a waste of spectrum resources;and the sidelobe of the filter is large too,which results in less flexibility of the system.On the other hand,FBMC as a candidate for 5G's waveform technology,compared with OFDM,its prototype filter has a better time-frequency characteristic,so it does not need CP to resist channel fading,and that makes FBMC system to be more spectrum efficient,and have more flexibility to take advantage of some of the existing non-continuous spectrum resources.Also,FBMC has a good compatibility for OFDM,so some of the techniques in OFDM can be applied directly to FBMC,but in order to obtain better time-frequency characteristics,FBMC sacrifices orthogonality between subcarriers.Therefore,compared with OFDM,its channel estimation is more complex.The current research situation of FBMC is analyzed and arranged in this paper,firstly.And with the research,conclusion can be drawn that finding the channel estimation technology and the combination with MIMO are the two hottest issues in FBMC.However,the current research on channel estimation is mainly focused on slow fading channel.Therefore,the main topic of this paper is focused on channel estimation techniques for FBMC,especially for fast fading channels.Following this,the basic principle of FBMC are introduced detaily,including the characteristics of the prototype filter,modulation,frequency domain implementation and time domain implementation using polyphase structure,and the complexity of the two implementation methods of FBMC is analyzed compared to OFDM.Secondly,this paper analyzes the channel estimation technology of FBMC/OQAM both in slow and fast fading channel.This paper introduces two kinds of classic pilot design algorithm in FBMC/OQAM,which are MIAM and AP namely.Based on the above research a new pilot design algorithm is proposed:pilot power doubling method,and it is more spectrum efficient,less complex in computing,and more important,its bit error rate performance has been greatly improved compared with traditional OFDM pilot design method.At the same time,this paper analyzes the pilot design in fast fading channel and finds that the auxiliary pilots can not keep track of the channel changes under the condition of fast fading channel.So this paper comes up with a kind of comb type pilot arrangement based on auxiliary pilot,and comes up with two kinds of channel estimation algorithm,feedback interference estimation algorithm and feedback interference calculate algorithm.It is proved by simulation that the performance of these two algorithms is better than original algorithm,and the computational complexity and spectral efficiency of the proposed algorithm are also analyzed respectively.Finally,this paper analyzes the bit error rate of OFDM and FBMC in the doubly selective channel.From both in theory and simulation aspects,the conclusion can be drawn that the robustness of FBMC in the fast fading channel is better than OFDM.At the end of this paper,research of the project is summerized,and some other FBMC problems to be solved as well as the future research directions are mentioned.