Wideband modeling of the acoustic water pipe channel

In this work we describe our investigation into wideband channel models for the acoustic water pipe channel operating over the 10-50KHz frequency band. We provide experimental results for a straightforward water pipe system consisting of a single pipe of length 6.3m, diameter 7.1cm, constructed from PVC and terminated with water tanks at each end in a hydrostatic configuration. It is observed that acoustic waves up to 50KHz can propagate through the water pipe and exhibit minimal propagation loss as a result of the pipe. There is also evidence to support the proposition that the pipe acts as a waveguide for acoustic propagation with associated modes. One key observation is that signals below around 15KHz cannot be transmitted through the water pipe without the use of high voltage projector sources. A model for acoustic wave propagation in rigid water pipes is also proposed to predict propagation loss and delay spread that incorporates modes. In addition we provide preliminary results demonstrating that wireless communication is feasible in the water pipe channel by providing bit error rate (BER) simulations for an OFDM BPSK modulated system using the experimental acoustic water pipe channel results.