Research And Implementation Of Sparse Channel Estimation Algorithm For Underwater Acoustic OFDM Based On Single Vector Sensor

Based on the communication interaction between UUV and AUV underwater formation,this paper studies and designs an underwater acoustic OFDM communication system based on single vector sensor.By improving sparse channel estimation technology and using single vector sensor for signal processing,the reliability and stability of communication between underwater vehicles are improved.On this basis,the computational load and complexity of the system are simplified.Finally,the whole system is implemented on the low cost and small size STM32H7 digital processing platform,so as to achieve the purpose of efficient and stable communication interaction between intelligent underwater vehicles.First,the sparse channel estimation technique of underwater acoustic OFDM is studied and improved.The underwater acoustic channel is analyzed and the model is established to master the underwater acoustic OFDM system.The LS channel estimation algorithm in the algorithm,the OMP algorithm based on compression perception study,aiming at the problem of traditional OMP algorithms depend on the prior information of the introduction of the LS-OMP channel estimation technology,and put forward using CZT Hermitian inner product improvement process to solve the problem of high precision estimate dictionary when matrix is too large.Through FFT,the system complexity is reduced,and the improved algorithm has obvious channel estimation advantage.Secondly,the processing gain is obtained by using a single vector sensor.The vector modeling of the single vector sensor is carried out to study its directivity.The combined processing of sound pressure and combined vibration velocity in different combinations is carried out and the directivity factor is derived.The processing gain of 4.8d B can be obtained during p（10）2v_c processing.The sound pressure channel and vibration velocity channel of a single vector sensor are regarded as multi-receiving systems,and the theoretical decoding bit error rate obtained by combining the maximum ratio of sound pressure and combined vibration velocity under the condition of QPSK modulation is derived.Combined with the sparse underwater acoustic OFDM system discussed in Chapter2,further system performance simulation is carried out,and it is verified that the lowest bit error rate of the p（10）2v_c combined processing is close to10^-3（signal-to-noise ratio of 20d B）under CZT improved LS-OMP algorithm.Thirdly,the underwater acoustic OFDM communication system based on single vector sensor was designed and built.The parameters and signal structure of the communication system were demonstrated and designed,and the hardware platform was designed.STM32H7 was selected as the digital signal processor,and the analog to digital conversion scheme,signal conditioning circuit form,power amplifier circuit and power supply module of the system were designed and built.According to the design of the hardware,the D/A transmission and A/D acquisition drivers are written,and the above improved algorithm is implemented in the system.Finally,the system test and sea trial are carried out.The simulation and digital parts of the electrical system are tested.The test results show that the electrical system meets the design requirements and the communication conditions.The communication test is carried out in the water tank to verify that the communication system can realize stable communication in the water tank.Finally,the correct rate of demodulation is output in the form of CRC check through the sea measurement of Daya Bay.In 1538 frames of data,1536 are correctly demodulated,and the correct rate is more than 99%,which meets the preset requirements of the system.