Research On Channel Estimation Technology Of GFDM Communication System

With the rapid development of wireless communication technology,many new multi-carrier modulation methods have been proposed one after another,of which Generalized Frequency Division Multiplexing(GFDM)has received widespread attention.GFDM overcomes the limitations of Orthogonal Frequency Division Multiplexing(OFDM)and has a series of advantages such as low peak-to-average power ratio,low out-of-band radiation,and high spectrum utilization.In the GFDM communication system,channel estimation technology is an important factor that affects the performance of the GFDM system.Only by obtaining accurate channel state information(CSI)can the bit error rate of the receiver be effectively reduced.Because GFDM is a non-orthogonal multi-carrier communication technology,the inherent interference in the system reduces the signal-to-interference ratio of the pilot signal,especially under the condition of time-varying multipath channels,the inter-carrier interference introduced by the channel(Inter Carrier Interference,ISI)and.Inter Sub-symbol Interference(ISI)will further reduce the signal-to-interference ratio of the pilot signal,resulting in reduced channel estimation performance.Therefore,it is of great significance to study the channel estimation technology of the GFDM system and improve the accuracy of channel estimation.In this paper,we study the GFDM channel estimation technology under the conditions of rare hydrophobic acoustic channel and time-varying multipath channel.First,the basic principles and performance of the GFDM communication system are studied.After that,the characteristics of underwater acoustic channels and the simulation technology of underwater acoustic channels are introduced.Based on this,the sparse characteristics of underwater acoustic channels are used to design a sparse hydrophobic acoustic channel estimation algorithm based on compressed sensing technology,respectively for OFDM and GFDM systems.Compressed sensing technology is used for channel estimation.Compared with OFDM,GFDM is verified to be more suitable for transmission on time-varying channels such as dilute hydrophobic sound channels.In addition,the algorithm of sparse hydrophobic sound channel estimation based on compressed sensing technology is analyzed through simulation comparison Differences in performance from traditional channel estimation techniques.Finally,for the GFDM channel estimation technology under time-varying multipath channels,in order to reduce the interference of ICI and ISI to the pilot signal,this paper proposes an interference cancellation channel estimation scheme based on index modulation(Index Modulation,IM).The index modulation technique is adopted around the pilot symbol of GFDM,and the signal-to-interference ratio of the pilot signal is improved by adjusting the number of active subcarriers and Sub-symbols,thereby improving the quality of channel estimation.The channel estimation mean square error calculation formula of the channel estimation method based on matched filter receiving technology using the index modulation interference cancellation scheme is derived,and the channel estimation performance simulation under the condition of time-varying multipath channels verifies the effectiveness of the scheme.