A unicast based gradient routing protocol for asynchronous duty-cycling UWSNs

In underwater wireless sensor networks, asynchronous duty-cycle MAC protocols and gradient based routing protocols can be used in order to extend network lifetime and provide network scalability, respectively. However, in asynchronous duty-cycle MAC protocols, the advertisement message which is essential in gradient based routing protocols cannot be broadcasted efficiently. In this paper, we propose a unicast-based gradient routing protocol (UGRP) in order to get along with asynchronous duty-cycle MAC protocols. Especially, in UGRP, each node makes own gradients maintained by unicast transmissions.