Opportunistic Data Forwarding And Transmission For Underwater Sensor Networks

As a method to observe and explore ocean,underwater acoustic sensor networks have become a new research topic,which have various applications,such as marine biology,marine exploration,deep sea archeology and so on.As the electromagnetic wave is easily absorbed by water,it is not suitable for underwater communication with long distance.Alternatively the underwater sensor network widely applies sound wave for communication.The underwater sensor network is composed of two parts:underwater part and wireless part on water surface.However,the underwater environment is very harsh for the underwater acoustic channel has the features of long delay,narrow bandwidth and high bit error rate.In addition,the node battery energy is limited,it is difficult to be charged or replaced,and the deployment and maintenance of the node is also very difficult.This becomes a great challenge to design an efficient underwater sensor network routing protocol.The cost of the protocol will further reduce the limited bandwidth of the underwater acoustic channel.However,the bandwidth of the wireless network is wide,the propagation speed is high,the delay is short,the difference between the bandwidth of the underwater acoustic link and the wireless link resulting in the transmission rate mismatch,data forwarding to the the surface of the routing efficiency is reduced.How to design end-to-end,unified and efficient routing and forwarding strategy cross water and surface wireless network becomes an important issue.In order to make the forward of the collected sensor data effective,this paper presents a novel data opportunistic forwarding and transmission method for the underwater sensor network,namely,On-Surface Wireless-Assisted Opportunistic Routing for Underwater Sensor Nerworks,SurOpp.SurOpp deploys multiple buoy nodes on the surface,and includes all of them in the forwarding candidates to form a receive diversity.The opportunities of reception and forwarding in buoy nodes are exploited to improve the end-to-end transmissions.SurOpp also adopts rateless codes in the source to achieve opportunistic reception in the sink,which improves the performance of the route.The cooperation of both opportunistic reception in the buoys and the sink further reduces the messages of control overhead.The wireless interface in the buoy undertakes all the messages exchanges in forwarding coordination to compensate the bandwidth limit of the acoustic channel.In order to analyze and evaluate the proposed underwater sensor network routing protocol,this paper uses NS3 to model and simulate.The simulation results show that SurOpp outperforms the traditional routing and existing opportunistic routing in terms of packet delivery ratio,end-to-end delay and energy consumption.