Research And Implementation Of Underwater Acoustic OFDM Communication System With Wake Up Mechanism Based On USRP Platform

The development of the marine economy,the protection of marine ecological resources and the building of a marine power are the strategic plans of "The 13th FiveYear Plan".To develop marine science and encomy,underwater acoustic communication(UAC)is the key technology.Although UAC technology has been studied in recent decades,it is still shackled by the unique underwater acoustic channels with strong space-time-frequency variability.Compared with terrestrial wireless communication,an accommodate channel model is unavailable till today.The best way to assess the performance of UAC systems still relies on the real field trials.Therefore,a real-time,rapidly prototyping UAC online system is of great theoretical significance and application meaning for the development of marine since and encomy.This thesis aims to build a software-defined UAC system evaluation platform over Universal Software Radio Peripheral(USRP)and the open-source software framework GNU Radio,where an underwater acoustic baseband OFDM communication system is realized.It presents a real-time performance evaluation platform for newly researching UAC algorithms,meanwhile,it is a feasible reference for developing software-defined UAC systems.In order to reduce the complexity of the receiver design,baseband OFDM technology without central carrier is adopted.Compared with traditional passband OFDM system,the baseband OFDM is not affected by the carrier frequency offset(CFO).Furthermore,a wake-up mechanism adaptive to the channel conditions is proposed to reduce the energy consumption.Based on this wake-up mechanism,a practical frame synchronization method is realized on our developed UAC system.Summarily,the contribution of this thesis are as follows:(1)Based on the universal software radio peripheral USRP and the open-source software framework GNU Radio,it was the first domestic implementation of an online underwater acoustic baseband OFDM communication system with wake-up mechanism based frame synchronization.The trials in experimental pool demonstrate the feasibility of the online UAC system.(2)A channel-adaptive underwater acoustic wake-up mechanism is proposed.The outdoor lake trial and sea trial channel simulation results verify that the detection probablility of wake-up mechanism is more than 0.95 and its false alarm rate is less than 0.01 in a long-delay,strong noise(-5dB)environment.