Physical layer design consideration for Underwater Acoustic Sensor Networks

Unlike that of terrestrial sensor networks, the physical layer design of Underwater Acoustic Sensor Networks (UW-ASNs) faces far more challenges because of the limited band-width, extended multipath, refractive properties of the medium, severe fading and large Doppler shifts. This paper takes a tutorial overview of the physical properties of acoustic propagation, modulation schemes and power efficiency that are relevant to the physical layer design for UW-ASNs, and analyses the design consideration on each aspect. In the end, it presents several open research issues, aiming to encourage research efforts to lay down fundamental basis for the development of new advanced underwater networking techniques in the near future.