Design And Implementation Of IS-LDPC Code To Reduce PAPR In FBMC System

As a more advanced multi-carrier communication method based on filter banks and using interleaved quadrature amplitude modulation,FBMC-OQAM technology has been favored by many scholars in recent years,and with its own small side lobes and high frequency spectrum The use of many advantages has become a research hotspot at home and abroad.However,as we all know,in the process of studying multi-carrier communication,the peak-to-average ratio(PAPR)phenomenon is inevitable,but some of the more mature peak-to-average ratio suppression schemes in OFDM are difficult to implement directly in FBMC.The suppression of high PAPR has become a barrier for the further promotion and application of FBMC technology.In view of this problem,this paper designs a scheme to reduce the PAPR of the FBMC system using IS-LDPC codes.First,this paper designed an IS-PEG algorithm for the construction of IS-LDPC;then,according to the characteristics of the IS-LDPC code reversible subset can be flipped independently and the resulting codeword is still a legal codeword,we use The way of inserting the flag bit allows the code words of the corresponding packet to flip and record the flip information,thus providing a possible set for the screening of low PAPR signals;then,for the overlapping characteristics of the FBMC signals,we designed a multi Symbol coding subset joint optimization scheme,used to optimize multiple FBMC symbols as a whole;based on the architecture,this paper proposes a low-complexity objective function for solving the optimal legal codeword in the set.The final Matlab simulation results prove that the IS-LDPC code constructed using the IS-PEG algorithm has excellent error correction capabilities,and at the same time,combined with the multi-symbol encoding subset joint optimization algorithm can effectively reduce the peak-to-average power ratio of the FBMC system When the number of reversible subsets increases,the effect of this scheme on suppressing the peak-to-average ratio is more significant.Finally,in order to verify the effect of the design of this article in the engineering implementation,we used the USRP RIO equipment produced by National Instruments(National Instruments)to complete the construction and test of the system.The system is divided into the following modules: signal transmission,frame synchronization,sliding window,FFT and frequency despreading,channel estimation and equalization,demodulation,decoding module,etc.,using the LabVIEW software platform to implement each module,and gives a block diagram With related instructions,the next experiment is to analyze and compare the waveforms and data in the USRP RIO panel,and draw the frame error rate curve of the IS-LDPC code according to the transmission power and the frame error rate information dynamically displayed on the front panel.The conclusion is proved that the scheme is feasible.To sum up: In this paper,through the IS-LDPC reversible subset feature,the IS-PEG algorithm is designed to construct the IS-LDPC code,combined with the multi-symbol encoding subset joint optimization architecture,a practical and feasible FBMC suppression The scheme of system peak-to-average ratio,and then the performance of the scheme was verified by Matlab simulation,and finally implemented based on USRP RIO equipment.