On the Design of Underwater Acoustic Cellular Systems

The design of a cellular underwater network is addressed from the viewpoint of determining the cell size and the frequency reuse pattern needed to support a desired number of users operating over a given area within a given system bandwidth. By taking into account the basic laws of underwater acoustic propagation, it is shown that unlike in the terrestrial radio systems, both the cell radius R and the frequency reuse number N must satisfy a set of constraints in order to constitute an admissible solution (which sometimes may not exist). The region of admissible (R, N) defines the possible network topologies. It is determined by the user density and the system bandwidth (rho, B), and by the required signal-to-interference ratio and per-user bandwidth (SIR_o, W_o). The range of admissible solutions also depends on the choice of operating frequency region. Moving to a higher frequency region than that dictated by SNR maximization, improves the SIR and yields a greater system capacity.