Research On Underwater Acoustic Wireless Video Transmission Technology On OFDM

Underwater acoustic video can provide long-time successional timely and comprehensive data to scientists and engineers,and it makes the underwater acoustic wireless video communication a wide range of applications,such as oceanographic observation,ocean engineering,offshore security,and ocean environment monitoring,etc.The transmission of underwater video has features of large data volume and highly real-time.However,the band-limit underwater channel,high bit error rate of communication,and long feedback time bring huge challenges to the underwater acoustic video transmission.To work out the problem of underwater uncooperative point to point wireless video transmission,this paper starts the research on two ideas: first,using high compression ratio video code to reduce the signal data volume,and improving the communication rate by adopting OFDM and high-order modulation method.Then,the video is packet to streaming media,and the strategy of dividing the different types of code frame is used to improve the environment adaptation.First,this paper uses the information source processing technology of streaming media to reference,and uses it to the underwater acoustic wireless video communication.By analyzing the features of the underwater video,we find underwater video have a lot of redundant which means the video can be compressed under high compression order.Then the simulation results show that PSNR of video frame under high compression order are reasonable.Secondly,this paper uses the information channel technology of streaming media to reference,and carry research on underwater acoustic wireless video transmission under high modulation order.Aim at the problem that the FFT number and computation will increase rapidly under the conditions of high center frequency and limited band-width,this paper adopts ZFFT to realize OFDM and reduce the computations.Then for the large cache length of the resampling OFDM video frames,this paper uses the CP to realize synchronization.In the OFDM modulation,this paper adopts 16 QAM and 16 APSK as the modulation methods,and LDPC+BCH as the error-correcting code to improve communication rate and error-resilient performance.And simulations are given in the end.Then,Underwater communication will face high error rate,we proposed the strategy of unequal error protection based on the analysis of the compression file and the streaming file format to reduce the error.The strategy includes file header repeatedly sending and unequal error protection between key Tags and non-key Tags.we simulated the performances of the strategy under OFDM communication method.Finally,in the trial of our research team where is conducted in Bayuquan District ofDalian city,we tested the OFDM communication and dividing strategy.The results show that,the transmission design can improve communication rate and the stability of the video communication.