On Optimizing Guard Interval Lengths for UWA-OFDM Communication Systems Using Geometry-Based Channel Modelling

This paper proposes a method to optimize the guard interval length of underwater acoustic (UWA) Orthogonal Frequency Division Multiplexing (OFDM) systems by using the geometry-based UWA channel modelling. The guard interval lengths are determined in depending of the influences of UWA channel parameters on the system performance. Based on the geometry-based UWA channel simulator, a set of parameters including the numbers of scatterers, the transmission distances, and the depths of the transmitter and the receiver, are investigated for the guard interval length optimization. Using the numerical simulation results, we can determine the guard length not only to prevent the inter symbol interference (ISI), but also to minimize the power consumption and increase the spectral efficiency of UWA-OFDM systems for a given transmission scenario. The proposed scheme can be used as a practical guideline to determine appropriate guard lengths for the design of UWA-OFDM systems.