Research On The OFDM Technology In The Underwater Acoustic Communication

The limited channel bandwidth and ISI introduced by channel multipath propagation are the obstacles for underwater acoustic (UWA) communications. Orthogonal frequency division multiplexing (OFDM) is a bandwidth-efficient modulation scheme with robutness to frequency selective fading. To attain reliable data transmission over UWA channels, the key techniques of OFDM aimed for UWA communications are studied in this thesis. And the results of simulation study and lake trial proved its excellent performance. The main content of this thesis are as follows:1. Talking about the orthogonality of OFDM and explaining realization principle of OFDM system based on IFFT / FFT.2. Making a research into channel estimating arithmetic.Introducing the theory of massive pilot and pectination pilot. And comparison of the advantages and disadvantages of both. By comparison we choose massive pilot insert method and the minimum square estimation to simulate. As can be seen from the simulation results, Using massive pilot insert method and the minimum square estimation can attain good effect. But with the frequency increase, performance will gradually deteriorated.3. Making a research into peak-to-average power ratio(PAR), Respectively selecting confining range algoritlim and partial transmit sequence(PTS) algorithm to progress system simulation. In spite of different mechanism, both of sides can attain better performance on reducing peak-to-average power ratio(PAR).4.A OFDM simulation platform was designed and validated that the technology referring above play a key role.5. Out of necessity of project, The experiment was carried out in Songhua...