Path loss analysis of RF waves for underwater wireless sensor networks

Abstract

Radio waves are preferred to acoustic and optical waves for underwater wireless communications for shallow water real-time applications. However, for deep water communication, acoustic waves are preferred to electromagnetic waves as acoustic waves are capable of propagating through compressions and rarefactions. Moreover, acoustic waves require high power for underwater transmissions. Radio waves have a different mechanism of propagation than acoustic waves. Also, radio waves have higher data rate underwater than acoustics. This leads to low power usage by underwater sensors. Therefore, radio frequency electromagnetic waves can be employed to address constrained battery life issue in underwater wireless sensor networks. Attenuation loss in seawater depends on temperature and salinity of the wireless medium and frequency of propagating radio signal. Temperature and salinity both changes with variation in depth. This leads to lower attenuation of radio waves in deep water as compared to shallow water. Our research analytically establishes the fact that radio waves are suitable for deep water communications by using acoustics as a complementary technology. In this paper, an extensive study of path loss analysis is provided for radio waves in case of shallow and deep water sensor networks.