Abstract
Underwater acoustic (UWA) communication techniques have gained popularity for wireless communication in shallow and deep seas. Orthogonal frequency division multiplexing (OFDM) has established to be a reliable multicarrier modulation method for a UWA communication for fending-off inter symbol interference (ISI). Since the UWA channel happens to be frequency selective in nature because of having multipath signals as a result of transmitted signals bouncing off the sea floor and/or the surface, equalization techniques must be utilized to counter the effect of fading. Therefore, we propose a least-squares error (LSE) based channel estimation technique using pilot subcarriers for UWA OFDM. Simulation results using a Rician fading based underwater channel model show that a reasonable number for the pilots is one-fourth of the number of sub-carriers. Any further increase in the number of pilots does not improve error performance. Moreover, error performance degrades as the energy of the pilots is increased.