Multimodal Acoustic-RF Adaptive Routing Protocols for Underwater Wireless Sensor Networks

In multi-function underwater wireless sensor networks (UWSNs), multiple applications share the same physical infrastructure to fully exploit network resources. Under such scenarios, diverse packets coexist in the same network which require differentiated delivery strategies to satisfy application demands, such as ocean monitoring packets and multimedia-based intrusion detection packets (e.g., video streams, voice or images) demand versatile support for data forwarding operation. However, the limited bandwidth and high propagation delay of acoustic channel pose great challenges to satisfy such demands. A feasible solution to solve such a problem is to exploit multimodal networks which integrate complementary acoustic and non-acoustic technologies to enhance transmission capability. Therefore, in this paper, we leverage both surface wireless radio frequency (RF) and underwater acoustic technology to fulfill different performance requirements of underwater sensor networks. We first propose two multimodal acoustic-RF adaptive routing schemes, and identify the major factors which influence the performance of these adaptive protocols. Then, we conduct extensive evaluations of the algorithms for both grid and random deployment scenarios. The simulation results confirm the feasibility of the proposed multimodal acoustic-RF routing protocols under diverse communication scenarios and channels.