Design And Implementation Of SC-FDE Data Transmission System For Unmanned Ship At Sea

The single carrier frequency domain equalization(SC-FDE)technology has been included in the IEEE802.16 a standard as a physical layer modulation technology because of its outstanding anti-multipath capability and low implementation complexity.In view of the hardware conditions and sea surface channel characteristics of maritime unmanned ship data transmission,the advantages of low peak-to-average ratio and insensitivity to frequency deviation of SC-FDE technology can well meet the needs of unmanned ship data transmission.However,the SC-FDE technology is more sensitive to timing deviation,and the Doppler shift caused by relative motion will also affect the communication quality.Aiming at the problem of time slot change in SC-FDE burst communication,this paper designs a carrier synchronization method based on a multi-mode frame structure;under the current mainstream hardware equipment conditions,the transmission rate supported by the existing timing synchronization algorithm cannot meet the specific In response to the needs of the scenario,a timing synchronization algorithm suitable for twice oversampling signals was designed,and Matlab simulation and FPGA implementation of the system and algorithm were carried out based on the SC-FDE technical solution.The main work and innovations include:1.Aiming at the shortcomings of the quadruple oversampling timing synchronization algorithm,this paper designs a double oversampling feedforward timing synchronization method without data assistance.First,divide the twice oversampled signal into three groups,then use the grouped signal to calculate the timing deviation,then calculate the interpolation base point and interpolation coefficient through the timing deviation,and finally interpolate the original twice oversampled signal to obtain a double symbol rate timing signal.It is proved by simulation that the double oversampling timing synchronization algorithm,compared with the original algorithm,reduces the computational complexity while ensuring that the timing deviation estimation accuracy is not reduced,and at the same time satisfies the project’s requirements for higher data transmission rates.2.The existing carrier synchronization method cannot adapt well to the changing communication time slot in the SC-FDE burst data transmission.To solve this problem,a frame structure suitable for the unmanned ship’s SC-FDE burst communication time slot is designed.By calculating the autocorrelation function of the preamble sequence and the unique word(UW)sequence and adjusting the differential correlation length,a carrier synchronization method suitable for multi-mode frame structure is proposed.It is proved by simulation that the multimode frame carrier synchronization method can adapt to the change of the time slot in burst data transmission on the one hand,and on the other hand,this method improves the accuracy of frequency offset estimation under the premise of the same estimation range as the existing algorithm,which is an algorithm engineering The main design of the realization provides reference.3.Based on the ZYNQ7045 platform and the SC-FDE technical solution,the FPGA implementation of the SC-FDE communication system and its key algorithms was completed,and the board-level performance test was carried out.Under the test conditions of the AWGN channel and the dual-path channel,the error performance and resource occupancy rate of the SC-FDE data transmission system can meet actual engineering needs,providing effective technical support for subsequent engineering practice and product development.