Transmitting Information by Propagation in an Ocean Waveguide: Computation of Acoustic Field Capacity

Abstract

Abstract : The maximum rate at which information can be transferred without error by acoustic wave propagation between two spatially distinct regions in an ocean waveguide is investigated by applying information-theoretic principles. An expression for this upper bound on transmission rate (i.e., information capacity) is determined within an ocean environment comprised of a penetrable, absorptive bottom with spatially uniform sound speeds and densities for both the water column and bottom, in conjunction with a correlated noise field. The acoustic source is described by a continuous, spatially confined distribution and, together with a receive volume, can be viewed in the context of multiple input multiple output (MIMO) communications between source and receive regions in the waveguide. In this scenario, the acoustic field is interpreted as a carrier of information in the information-theoretic sense, and an expression for the field capacity using a full wave formulation of propagation in this waveguide is derived. Using the compactness of the Green function operator and singular value decomposition, the capacity is written as a sum of link capacities identified with independent pseudo-channels, subject to constraints on the source power distribution among these channels and knowledge of the environment at the transmit region