Depth-based Opportunistic Routing Algorithms For Underwater Acoustic Sensor Networks

As the underwater acoustic sensor network has a great application foreground in ocean environment protection,ocean disaster monitoring,ocean work and maritime safety,it is attracting more attention from many countries,industrial community and academic community in recent years.The routing algorithm is the key point in forwarding packets fleetly and reliably for underwater acoustic sensor networks,it is one of the popular topics in recent years.This dissertation investigates the opportunistic routing algorithms for underwater acoustic sensor networks.We add adaptive threshold and differentiated service mechanism into classical DBR(Depth-Based Routing)algorithm,and propose three improved depth-based opportunistic routing algorithms.In addition,the proposed algorithms are evaluated by extensive simulations.This dissertation firstly summarizes the feature and network structure of underwater acoustic sensor networks,and analyses the research status of routing algorithms for underwater acoustic sensor networks.According to the next hop candidate node selection,we sum up the classical routing algorithms for underwater acoustic sensor networks.And we analyze the advantage of opportunistic routing in underwater acoustic sensor networks.In addition,we analyze the main idea of DBR algorithm,and point out its limitation of fixed depth threshold in next hop candidate set selection.Based on the adaptive depth threshold mechanism,we propose a Depth-Based Routing with Adaptive Threshold(DBR-AT)algorithm.This algorithm adjusts the depth threshold adaptively according to the network node density.In sparse networks,nodes decrease the depth threshold automatically to improve the packet delivery ratio.In high density networks,nodes increase the depth threshold dynamically to decrease the redundant packet copies.In order to further decrease the redundant copy number of DBR-AT algorithm and to reduce network energy consumption,we add the mechanism of removing fixed blind zone in EE-DBR into DBR-AT algorithm,and propose an Energy Efficiency Depth-Based Routing with Adaptive Threshold(EE-DBR-AT)algorithm.This algorithm combines the advantage of EE-DBR algorithm and DBR-AT algorithm,and it is superior to the existing algorithms in terms of network energy consumption and packet delivery ratio.Moreover,as DBR algorithm does not support differentiated service,and does not meet the different quality of service of underwater applications,we add the mechanism of differentiated service into DBR algorithm,and propose a Differentiated Service Depth-Based Routing(DS-DBR)algorithm.According to the different quality of service of underwater applications,this algorithm divides data packets into high and low priority.And it provides different policies for next hop candidate set selection and node cache queue management according to the priority of packets.In addition,this algorithm has packet retransmission mechanism as to high priority packets,in order to further improve the packet delivery ratio.Finally,we develop the three proposed algorithms using NS2 simulation platform,and compare them with the existing algorithms in the literature by extensive simulations based on the NS2 simulation platform.Simulation results verify the effectiveness of the proposed algorithms.