Localized Hop-Count Based Routing (LHR) Protocol for Underwater Acoustic Sensor Networks

Underwater Acoustic Sensor Networks (UASNs) is one of the emerging fields in the area of communication due to the number of applications. UASNs face several challenges like limited energy and bandwidth, high bit error rate, packet loss, node mobility, low propagation speed, and routing. Underwater routing is challenging due to the dynamic topology. Many routing protocols used in the UASNs use the hop-count of the neighbor as one of the attributes to select the next-hop. However, due to changes in underwater topology, hop count changes frequently. Obtaining up-to-date hop-count information is one of the major challenges. Many protocols send beacons periodically to update the hop-count, which creates overhead on the network. This paper proposes a Localized Hop-count based Routing (LHR) protocol, which uses a novel mechanism to determine hop-count. Hop-count in LHR is determined based on the local attributes of neighbors. LHR avoids periodic transmission of the beacons from the sink. Thereby, LHR reduces the overhead of transmitting beacons from the sink node periodically. Further, LHR makes use of metrics such as hop-count, depth, and distance for selecting the next-hop.