Research On CDMA Based Multi-user Of Underwater Acoustic Communication

In modern marine military defence and commercial ocean development, the underwater acoustic communication is indispensable. We need to transmit informations among different naval ships, submarines, UUV/AUV. It is necessary to build a underwater acoustic network to link all these nodes.This paper organizes discussion around the realization of underwater acoustic network's physics layer. The main problem is how to transmit information among users. In the paper use CDMA as theoretical basement to realize communication. The main work in this paper include:First of all, we expatiate the elements of Direct Sequence-Spread Spectrum Communication (DSSS) System. The emphasize is put on two modulate ways -BPSK&QPSK, and compare the performance of them. A ameliorate spread code is proposed in this paper which used m sequence as basement. To conquer the interference of multipath and phase shift the author introduce an adaptive equalization technology.Then, Frequency Hopping-Spread Spectrum (FHSS) Communication System theory was introduced in this paper. To chooce the code perfermence good in self-correlation and cross correlation we used unrepeated hopping sequence. And it has the biggest spread spectrum gain. Channel coding technology also used in these two systems to improve the quality of communication.At last we build simulation platform and simulate these two system in it. To compare different condition we draw some conclusion.