01720nas a2200193   4500000000100000008004100001100001900042700001800061700001700079700001700096700001800113700002200131245006200153856004300215300000800258490000700266520123900273022001401512       2016                            d1 aRodrigo Santos1 aJavier Orozco1 aSergio Ochoa1 aRoc Meseguer1 aGabriel Eggly1 aMarcelo Pistonesi00aA MAC Protocol to Support Monitoring of Underwater Spaces  uhttp://www.mdpi.com/1424-8220/16/7/984  a9840 v163 aUnderwater sensor networks are becoming an important field of research, because of their everyday increasing application scope. Examples of their application areas are environmental and pollution monitoring (mainly oil spills), oceanographic data collection, support for submarine geolocalization, ocean sampling and early tsunamis alert. The challenge of performing underwater communications is well known, provided that radio signals are useless in this medium, and a wired solution is too expensive. Therefore, the sensors in these networks transmit their information using acoustic signals that propagate well under water. This data transmission type not only brings an opportunity, but also several challenges to the implementation of these networks, e.g., in terms of energy consumption, data transmission and signal interference. In order to help advance the knowledge in the design and implementation of these networks for monitoring underwater spaces, this paper proposes a MAC protocol for acoustic communications between the nodes, based on a self-organized time division multiple access mechanism. The proposal was evaluated using simulations of a real monitoring scenario, and the obtained results are highly encouraging.  a1424-8220