Design And Hardware Implementation Of SC-FDMA Baseband System Based On FPGA

In recent years,with the development of wireless communication technology,scattering communication has been widely used in military communication and disaster emergency because of its advantages of long communication distance,strong anti-interference ability,and high reliability.Because it uses the scattering effect of the scatterers in the atmosphere to communicate,the channel transmission loss is relatively large.Due to the multipath effect and the Doppler effect,the scattering channel has serious time-selective fading and frequency-selective fading characteristics.A communication system with reasonable channel characteristics is particularly important.In this thesis,the SC-FDMA baseband system is designed and implemented according to the characteristics of the scattering channel.The thesis first introduces the background and significance of the research,introduces the characteristics of scatter communication,SCFDMA technology and FPGA technology,and expounds the main work and structural arrangement of the thesis.Then the basic parameters of the system are designed according to the current scattering channel,including system bandwidth,working mode,channel division and so on.The design of the baseband system adopts DSP+FPGA to realize the architecture.DSP is responsible for bit-level data processing,including encoding and decoding,interleaving and de-interleaving,etc.,while FPGA completes modulation and demodulation.Then take the downlink receiver and transmitter as examples,design and verify some of the FPGA algorithm function modules.The system uses transform domain diversity and equal gain combining technology to resist channel fading.Modulation methods include BPSK,QPSK and 8PSK;block pilots suitable for frequency-selected channels are used;cyclic prefixes with reasonable lengths are designed according to the maximum delay of scattering channels;Select a constant amplitude and zero autocorrelation waveform with good autocorrelation and cross-correlation characteristics as the synchronization header sequence;adopt shaping matched filter processing to make the signal suitable for channel transmission.At the receiving end,firstly complete bit synchronization and frame synchronization through timing synchronization;complete frequency synchronization through frequency offset estimation and compensation;estimate signal-to-noise ratio based on pilot;use least-squares method for channel estimation;use least mean square in combination with signal-to-noise ratio The error method is used for equalization;finally,the soft information obtained by data demodulation is transmitted to the DSP.Secondly,the interactive interface between DSP and FPGA is designed according to the system requirements using SRIO interface,and related transfer parameters are designed.At the same time,according to the working status of the base station and the user,the working timings of the base station and the user are designed respectively.Finally,the system was tested on the board and tested with the radio frequency,and the resource consumption and processing delay in the test results were analyzed.The implementation results show that the currently designed SC-FDMA baseband system can be well applied to the current scattering channel,and it still maintains good communication performance in a low signal-to-noise ratio environment.