Climatical Characterization of Northern Arabian Sea for OFDM Based Underwater Acoustic Communication

Abstract

The effects of climatic changes on the Underwater Acoustic (UWA) communication are addressed here with the aim to evaluate the performance of proposed scheme in the whole year specifically for the north Arabian Sea. Oceanic channel is a most challenging medium for the design of underwater wireless communication as it offers various unwanted degradations in terms of frequency-dependent attenuation, multipath spread, long path delays, etc. Multipath spread having extended delay spread further deteriorates the communication packet (s) and in result, mutilation of entire signal, i.e., Inter-Symbolic Interference (ISI) is occurred. Detailed analysis for the interaction of sound wave with the water mass is essential for the design of Underwater Acoustic (UWA) communication. In particular, at varying temperature and warm surface site like Ormara, Pakistan (north-western region of Arabian Sea), where a very strong seasonal dependency may be observed due to climatic changes. OFDM, being the most feasible communication scheme and well suited for underwater environment is utilized in this study for the effect's monitoring. In this study, we are presenting the effects of climate on the selected region of North-west Arabian Sea and validating our work on Zero Padded (ZP) OFDM scheme for UWA communication. Relevant meteorological and oceanic data are obtained from open source buoy ARGOS ID 2901374 and Global ARGOS marine atlas (Worldwide tracking and environmental monitoring by satellite). For each of March, June, September and December we find a temperature and salinity with respect to the depth and subsequently calculate the sound speed in the specific channel. Bellhop ray tracing program is used to obtain the receiving path's amplitudes and delays for respective channel modeling and ZP OFDM based communication system. Simulation results explain the effects of climate in the transmission and endorse that ZP-OFDM is a viable choice for high-rate communications in these types of oceanic channel. In this way system level design of the underwater acoustic wireless communication/telemetry can be optimized for the most prevailing channel conditions.