Scale model analysis of full-duplex communications in an underwater acoustic channel

Due to issues of in-band artifacts produced by a transmitter that would otherwise influence or jam an adjacent receiver in the near field, current underwater acoustic communication systems employ half-duplex algorithms. This limits the information transfer between nodes to exclusively send or receive at any given time. The use of full-duplex communications, allowing simultaneous send and receive protocols to be employed, could help improve data transfer rates and error checking. A direct evaluation of the effectiveness of full-duplex transmissions is investigated in a scale-model, shallow water waveguide. The results of simultaneous two-way communications achieved through the use of adjacent, nonoverlapping frequency bands are presented. In this case, use of appropriate filtering of the receptions is being used to minimize cross-talk between bands. Different elements of the arrays are also assigned specific operating bands in order to help reduce cross-talk. The use of orthogonal signals (such as PRN sequences) over common bands is also discussed.