Research On Barrier Coverage Algorithm For Optimizing Surveillance Quality And Network Lifetime In Wireless Sensor Networks

Wireless sensor networks(WSNs)have been widely applied in many fields for its low cost,low power consumption,and easy to deploy.As a fundamental issue of WSNs,the coverage problem has been the research hotspot in recent years.The research of barrier coverage is to detect the moving intrusion target by deploying the WSNs in the border,which is widely applied in national defense,hazardous region,and other important fields.The surveillance quality and network lifetime are two main indicators that measure the quality of barrier coverage.However,since the application scenarios of barrier coverage is usually a large area in the border,the scale of deployed WSNs is massive,and the energy,computation capacity,sensing and communication capacity of the nodes in WSNs are limited.Therefore,the research issue of designing the distributed barrier coverage algorithm,which aims to maximize the surveillance quality of the barrier and the network lifetime with the limited resource is crucial and challenging.The research of this dissertation aims to design an effective distributed barrier coverage algorithm to maximize the surveillance quality while perpetuating the network lifetime.The main contributions of this dissertation are presented as following.(1)In the views of the problem that the barrier coverage based on the Boolean sensing model(BSM)can not guarantee the surveillance quality,this dissertation proposed an effective barrier coverage algorithm(GSMS)in the WSNs with battery-powered,which aims to guarantee the surveillance quality with the minimal number of active sensors.Based on the probabilistic sensing model(PSM),this algorithm can calculate the detection capability to the different locations of its sensing range accurately.By partitioning the monitoring region into several grids,the computation complexity can be reduced.During the construction of the barrier,this dissertation proposed the concept of defense length contribution.Based on the defense length contribution,this algorithm selects the backbone node to construct and extend the barrier effectively.Then GSMS algorithm identifies the surveillance bottleneck crossing path and the surveillance quality of the barrier to this crossing path in the newly added surveillance region of the extended barrier.If the surveillance quality of the barrier to the newly added surveillance region is not qualified,this algorithm schedules the sensor with maximal detection capacity to this region as the auxiliary node to join the cooperative monitoring task which aims to guarantee the surveillance quality of the barrier with the minimal number of sensors.The simulation experiments prove that the proposed GSMS algorithm can construct the barrier that qualifies the requirement of surveillance quality with minimal number of sensors,and prolong the network lifetime by constructing more barriers in the monitoring region.(2)To cope with the problem that the network lifetime of the WSNs with battery-powered is limited,this dissertation proposed a distributed barrier coverage algorithm(MCDP)in rechargeable solar-powered WSNs,which aims to maximize the cooperative detection probability while perpetuating the network lifetime.This algorithm first partitions the time into several cycles,and each cycle is composed of several time slots.The length of each time slot and cycle is calculated based on the ratio of recharging and discharging rate of the sensor,and the length of daytime and nighttime.Then the MCDP algorithm partitions the monitoring region into several grids.This algorithm identifies the bottleneck space time point which has the weakest detection probability,then schedules the sensor with the largest detection probability to the bottleneck space time point staying in sensing state,and staying in recharging or sleeping state in the rest of time slots,which aims to maximize the surveillance quality while guaranteeing the balance of recharged and discharged energy.The simulation experiments result that the proposed MCDP algorithm can improve the surveillance quality of the barrier,and has good performance of fault tolerance.(3)In the WSNs with fixed sensing radius,since the node density of each local area in the monitoring region is various,the local area with higher node density may exist redundant monitoring capacity while the local area with lower node density may exist surveillance bottleneck space time point,to cope this problem and improve the sensor node utilization to maximize the surveillance quality,this dissertation proposed a distributed barrier coverage algorithm(AR-MSQ)in solar-powered WSNs with adjustable sensing radius,which aims to maximize the surveillance quality while perpetuating the network lifetime.The detection capability of the sensor to its sensing range and the sensing time of the sensor are considered as the space contribution and time contribution,respectively.The AR-MSQ algorithm first partitions the time into several time slots and the monitoring region into several grids.Then the algorithm selects the grids with the most potential to obtain the largest cooperative detection probability as the target grid.Finally,in sensor task scheduling phase,this dissertation proposed the farthest-first policy,that is,according to the distance between sensor and target grid,the AR-MSQ algorithm schedules sensors from far to near round by round.In each round of task scheduling,each sensor decision its sensing radius and design its task scheduling based on its local information,which aims to maximize the space contribution of each sensor to the surveillance bottleneck space time point.Besides,this dissertation designs a random back-off scheme to avoid the packet collision occurred among neighbor nodes when multiple sensors broadcast their task scheduling decision.The simulation experiments demonstrate that the proposed AR-MSQ algorithm can allocate the surveillance capacity of deployed WSNs to all the space time point more evenly,effectively improve node utilization and the surveillance quality.In general,the proposed three kinds of distributed barrier coverage algorithms optimize the surveillance quality and network lifetime of barrier significantly in different scenarios.Therefor,the research of this dissertation possesses good theoretical significance and application value.