Spatial encoding of communication sequences with an ocean acoustic time-reversal mirror

With the at-sea demonstration of producing simultaneous multiple focal spots with a TRM, spatial encoding of communication sequences is now possible. We present the results of an ocean acoustic experiment in which we demonstrate that different communication sequences can be simultaneously sent to and decoded at individual receivers on a vertical array. This ‘‘multiple input, multiple output (MIMO)’’ process significantly increases the acoustic communications band rate. Various incoherent and coherent communication temporal coding schemes are employed together with this spatial procedure.