Research On Opportunistic Routing Protocols Based On Network Coding In Underwater Acoustic Sensor Networks

Underwater Acoustic Sensor Networks(UASNs)has been widely applied as results of intrinsically prominent advantages of convenient deployment,low cost,flexibility,and extensibility.However,many factors such as complex underwater channel condition,highly dynamic of network topology,energy constrained of sensor nodes,and sparse deployment of networks pose serious challenges to the data transmission in UASNs.For the purpose of increasing the data transmission paths with high robustness,the opportunistic routing takes full advantage of the broadcast characteristics of wireless medium,and effectively utilizes long links or high loss links to forward packets,while suffering from the void problem and high redundancy transmission drawbacks.Network coding can improve the transmission reliability with low redundancy by forwarding the coded packets that are "compressed" by the multiple packets within a node.Thus,the combination of network coding with opportunistic routing strategies can further optimize data transmission in UASNs.This dissertation investigates the underwater opportunistic routing protocols based on network coding,and then optimizes the data transmission performance in three types of UASN scenarios.The main research works of this dissertation are as follows:Firstly,the key point of designing an underwater opportunistic routing protocol is inductivly combed in this dissertation according to the research of this dissertation.Moreover,the transmission models for intraflow coding and interflow coding are given and,then the research thought of opportunistic routing protocol based on network coding is summarized;the influence of typical coding parameters for data transmission in underwater is analyzed.Furthermore,the typical transmission problems in underwater networks are discussed based on underwater network model and theoretical channel model.Secondly,to address the hot terminal problem in static multi-hop UASNs,the dissertation proposes an underwater cross-layer-aided opportunistic routing protocol based on network coding.The protocol utilizes a fuzzy logic-based candidate algorithm to achieve the convergence of information such as single-hop link state,multi-hop forward progress,congestion state of a node.Furthermore,a hybrid candidate competition algorithm is applied to control the optimal candidate node to forward packets.On this basis,a network coding-based burst transmission mode is investigated to accommodate the non-uniform service flow of each node.Moreover,the performance advantages of handshake efficiency,burst transmission efficiency and forwarding based on network coding are theoretically analyzed.Simulation results show that the proposed protocol outperforms FBR and CARP in terms of packet delivery rate and goodput while also performs outstanding advantages in an aspect of end-to-end delay at low traffic rates.Thirdly,an opportunistic routing protocol based on interflow network coding with topology awareness is proposed to address the void problem in the underwater dynamic swarm network scenarios,where the nodes move as a group with the water current.The protocol constructs a candidate set based on hop count information and extends the candidate set with the network topological information.On this basis,this dissertation designs a forwarding with opportunistic coding mechanism based on interflow network coding.In addition,constraint parameters are used to control the cache interval,coding interval and coding sparsity to address multiple transmission requirements.Considering the data transmission characteristics of sensor swarm,this dissertation also designs a sliding-window-based coding algorithm with low coding overhead and a sliding-window-based decoding algorithm with low complexity.The advantage of candidate set expansion based on hop count information is theoretically analyzed and simulated.Simulation results show that the proposed protocol outperforms IVAR and DOVR,and can well adapt to link variation in UASNs.Finally,an opportunistic routing protocol based on intra-flow coding and depth information is proposed for overcoming the void problem in the network scenario with multiple autonomous mobile sensors.In this protocol,each node establishes a main forwarding candidate set and a temporary coding candidate set based on depth information: the nodes in the main candidate set execute opportunistic forwarding algorithm,whereas the nodes in temporary coding candidate set execute forwarding with opportunistic coding algorithm.In addition,this dissertation designs a sliding window-based algorithm with intra-flow coding by setting various sliding window parameters to control the coding for different transmission requirements.Simulation results show that the proposed protocol outperforms DBR and DOVR in terms of packet delivery ratio and can well adapt to link variation in the scenarios of a sparse UASN with signal source node.