SINR analysis of OFDM systems using a geometry-based underwater acoustic channel model

The Doppler effect is caused by the relative movement between the transmitter (Tx) and the receiver (Rx) and/or the surface motion (waves) in underwater acoustic (UWA) communication systems. The inter-channel interference (ICI) caused by the Doppler effect degrades the performance of orthogonal frequency-division multiplexing (OFDM) systems over UWA channels. This paper is devoted to the ICI plus noise analysis of UWA-OFDM systems over a geometry-based channel model for shallow UWA channels. We carry out the exact calculation of the ICI power, ambient noise power, and required transmit power, as well as their effects on the performance of UWA-OFDM systems. The signal-to-interference ratio (SIR) and the signal-to-interference-plus-noise ratio (SINR) performance are analyzed for different relative speeds of the Tx and Rx, signal bandwidths, and carrier frequencies. The results show that the SIR not only depends on the maximum Doppler frequency but also on the signal bandwidth and the transmit power. The ICI power increases if the maximum Doppler frequency or the transmit power increases. If the bandwidth increases, the ICI power decreases, whereas the ambient noise power increases. Based on the simulation results, the system parameters can be optimized for the design of UWA-OFDM systems.