Research On The Problems Of Barrier Coverage In Wireless Sensor Networks

In recent years, with the maturity of wireless communication and micro technology,barrier coverage strategies in wireless sensor networks(WSNs) has been widely applied to the military, border defense, industry and other areas. Barrier coverage is mainly used in border monitoring. How to construct barrier coverage efficiently and improve the network lifetime are two important issues in wireless sensor networks.After monitoring tasks in WSNs are determined, selecting fewer sensor nodes can construct more coverage sets to complete monitoring tasks and improve the network performance greatly. Furthermore, it will reduce the energy consumption of the network,degrade the communication overhead between sensor nodes and reduce the redundancy of neighboring sensor nodes. The goal of this thesis is to improve the algorithms of constructing the barrier coverage and by proposing an efficient algorithm to extend the network lifetime of barrier coverage.The third part of this thesis begins to state the contribution. The contribution of this thesis related to the problems of the barrier coverage in wireless sensor networks is as follows:Firstly, for the monitoring task of 1-barrier coverage, the traditional algorithm of constructing barrier coverage generates crossing barriers which can degrade the performance of the network. This thesis proposes two improved algorithms including constructing none crossing strong barrier coverage(CPBC) and constructing none crossing weak barrier coverage(CWBC). CPBC selects sensor nodes based on the method of Divide and Conquer. CWBC selects sensor nodes based on the method of top down selection. This thesis also proposes a new concept which is called imperfect barrier coverage. This thesis utilizes redundant sensor nodes to construct an imperfect barrier coverage between two neighboring perfect barriers to extend the network lifetime.Secondly, for the monitoring task of k-barrier coverage, the existing works mainly study the problems of sensing in k-barrier coverage. For the transmission, it is assumed that common nodes transmit messages to the sink node by one-hop. However, the communication radius is not so large enough, one-hop environment is limited. This thesis consider not only sensing but also communication in k-barrier coverage. In themulti-hop environment, there exists interference between neighboring barriers which can degrade the performance of the network. Based on the protocol interference model,this thesis devises an algorithm called interference-free k-barrier coverage. This thesis firstly analyzes how neighboring barriers generate interference in the monitoring task of k-barrier coverage then it designs an efficient distributed algorithm to construct an interference graph and constructs an interference-free k-barrier coverage based on the method of maximal independent set.Finally, this thesis builds up a network simulator and implements the proposed algorithms by JAVA programming language. The simulations show that for the monitoring task of 1-barrier coverage, CPBC is better than the traditional algorithm of constructing strong barrier coverage while CWBC is better than the traditional algorithm of constructing weak barrier coverage. CIBC can prolong the network lifetime of barrier coverage. For the monitoring task of k-barrier coverage in multi-hop environment, the interference-free k-barrier coverage algorithm based on the protocol interference model can improve the performance of barrier coverage greatly.