A Data Forwarding Approach For Opportunistic Mobile Sensor Networks In Fire-Rescue Scenario

In recent years,the theory and technology of opportunistic mobile sensor networks have attracted extensive attention from the government and academia.Compared with traditional networks,opportunistic mobile sensor networks do not require the full connectivity of networks,and they are available with the network communication requirements in many special environments.Note that the intermittence and uncertainty in the network mode,the complexity and diversity of the environment,and the diversity of sensor devices(memory,energy,etc.)have brought great challenges to message forwarding in mobile sensor networks.Therefore,it is necessary to design an effective data forwarding approach for different application scenarios.The opportunistic mobile sensor networks have been extensively used in various public safety applications such as the fire-rescue scenarios,emergency communications for natural disasters,and so on.In the fire-rescue scenario,the sensor nodes can be thrown into dangerous areas to collect environmental data,which can avoid the unnecessary injury to firefighters as far as possible.However,the sensor nodes thrown by firefighters in the fire-rescue scenario are easy to move away from original positions due to many environmental factors,such as the building structure damages,airflow push or even some explosions.Consequently,the contacts between nodes become scarce and momentary,thereby making the gathered data packets difficult to be forwarded along stable communication paths.First,the mobility patterns of nodes in the fire-rescue scenario are classified into four types: small-range mobile nodes,large-range mobile nodes,firefighter nodes and robot nodes.Then,the optimal proportions of three types of nodes(Small-Range mobile Nodes,Large-Range mobile Nodes,Firefighter Nodes)in the data holders are specially investigated mathematically,which ensures that the optimal relay nodes are selected to maximize the delivery ratio og messges under the constraints of the message forwarding overhead and the maximum delay.Thus,a Data Forwarding Approach for opportunistic mobile sensor networks in Fire-Rescue scenario(DFAFR)is proposed.In DFAFR,each data holder forwards the held data packets to neighbouring nodes independently,and the optimal proportions of data holders are maintained approximatively.Finally,the performance of DFAFR is analyzed through simulation experiments that produce preferable results in the fire-rescue scenario,indicating that DFAFR can improve the delivery ratio and shorten the delivery delay.Finally,a prototype system of a Data Forwarding Approach for opportunistic mobile sensor networks in Fire-Rescue scenario(DFAFR)based on Android is implemented.The system adopts DFAFR to complete message forwarding tasks between nodes through Android Bluetooth communication simulation.This paper studies the data forwarding problem for Opportunistic Mobile Sensor Networks in fire-rescue scenarios.In DFAFR,SRNs and LRNs can be distinguished according to the position stability of nodes.DFAFR improves delivery ratio by approximately maintaining the optimal proportion of different types of nodes in data-holding nodes,and new relay nodes are selected from candidate nodes and adjacent RNs according to the expected transmission delay of nodes.DFAFR is suitable for some emergencies,especially for fire rescue.In short,DFAFR can improve delivery ratio and shorten transmission delay with less forwarding overhead.However,there are still many shortcomings in the theory of this paper.For example,only the node mobility model and message forwarding algorithm in opportunistic mobile sensor networks are investigated,but the research points in opportunistic mobile sensor networks are far more than that.