Design And Implementation Of F-OFDM Downstream Filter Based On FPGA

With the clarification of the 5G vision and requirements,new application scenarios and services have higher requirements on the network speed,network capacity,latency,and reliability of communications systems.Based on the sub-band filtering-based Orthogonal Frequency Division Multiplexing(F-OFDM),by adding sub-band filtering,waveform parameters matching with service requirements can be configured to meet the needs of complex scenarios and services.On the transmitter side of F-OFDM system,by analyzing the similarities and differences between the F-OFDM and OFDM signal processing flow,the signal vector model of the transmitter of F-OFDM technology is given.In the case of multiple sub-bands,the transmission terminal sub-bands resource allocation method is analyzed under the principle of ensuring that the system's data sampling frequency is the same.At the same time,the mapping of sub-bands sub-carriers is performed through the method of uniform numbering of sub-carriers in the frequency band.When designing the sub-band filter,a window function design method based on the Hanning window is adopted,and a frequency domain filter with a lower computational complexity is selected as the filter scheme.At the receiving end,the method of matching filtering is selected to achieve the decoupling of the sub-bands,and the time-frequency efficiency of the F-OFDM technology in the IoT service,low delay,high reliability,and hot spot high capacity scenario is analyzed.The simulation results show that the error rate of F-OFDM system is basically the same as that of OFDM.The designed sub-band filter improves the out-of-band leakage suppression of F-OFDM system by 20 dB compared with traditional OFDM,and only needs less protect subcarriers as protection bandwidth.Finally,according to the structure of the transceiver of F-OFDM technology,it is divided into the generation of training sequences,insertion of pilots,implementation of IFFT/FFT,addition of cyclic prefixes,generation of sub-band filters,synchronization detection,channel estimation and equalization,etc.The seven modules were respectively implemented by FPGA,and the function simulation and timing simulation were performed.The experimental results show that the sub-band filter can realize the parallel transmission of multiple sub-bands.