Research On The Coverage And Connectivity Problem In Wireless Sensor Networks

Coverage and connectivity are two closely related fundamental prerequisites for wireless sensor networks working well. The coverage issue is to solve how to ensure that the coverage range meets the application requirements. The connectivity issue focuses on how to ensure that all the working nodes are able to communicate with each other. Connected coverage is the integration of coverage issue and connectivity issue. The integration covering both the capacity of coverage and connectivity in wireless sensor network is to solve the problem that coverage range of the network meets application requirements and at the same time the network is connective. The thesis makes an intensive study of the connected coverage problem in wireless sensor networks. The main works are presented in the following aspects:(1) This thesis analyses the characteristics of the wireless sensor network in a random manner of deployment, and points out that the distribution of the sensor nodes in the monitoring area is a Poisson point process, which accords with the random structure characteristics of Poisson Boolean model in the continuum percolation theory. A coverage percolation model is constructed in the wireless sensor network. And based on the model, the relations between the probability of the network covering the whole monitoring area entirely and the node deployment density are investigated. Then a new connected coverage model in the wireless sensor network is constructed and the relations between connected coverage probability and the node deployment density are investigated. Moreover, a basis for the node random deployment is provided in the wireless sensor network.(2) This thesis investigates the characteristics of the wireless sensor networks and works out the node density, which is enough to meet the connected coverage of the network, in the condition of the known node communication range and sensing range. Based on the results, this thesis proposes a new location-independent self-scheduling node connected coverage algorithm (LISSCA). The new algorithm runs by rounds and in every round it reselects the working nodes. The probability of each node becoming the working node is not only influenced by the number of its neighbor nodes, but also has a relationship with the remaining energy of itself and its neighbors. In addition, it can be adjusted dynamically by the network status. With node scheduling, the LISSCA algorithm is capable of controlling the number of the working nodes effectively, and balancing the energy consumption in the wireless sensor network. Consequently, it realizes that the energy is best used and at the same time the network lifetime is improved effectively. The simulation results turns out that the LISSCA algorithm is effective.