Research On The Problems Of Sensor Coverage And Deployment Under Constraints

In recent years, Wireless Sensor Networks(WSNs) develop in high speed, and gradually become the bridge connecting the physical world and the digital world. Sensor deployment is the first step to design WSNs. It has significant impact on coverage, connectivity, energy and lifetime in WSNs. Coverage is the basic problem of WSNs. It has significant impact on energy consumption and lifetime.The problem of sensor deployment in WSNs is to find an optimal topology subject to desired condition, an efficient topology can not only increase the performance of coverage and connectivity but also decrease energy cost and prolong network lifetime. While the WSNs perform the task of sensing, little working nodes can reduce energy consumption and data redundancy between sensors. This paper mainly studies the problem of sensor deployment satisfying the minimum number of sensors and the problem of minimum sensor coverage satisfying partially connectivity.These works related to sensor coverage and deployment are as follows:For the problem of sensor deployment satisfying the minimum number of sensors, this paper proposes a hybrid network structure, this network structure is composed by Bus-based Ad hoc Networks(BANETs) and WSNs. And based on this network structure, this paper proposes an algorithm of modifying strip-based sensor deployment with boundaries(MSSDB), MSSDB considers the boundary of the target area, and changes the deployment pattern between the strip-based and the triangle-based deployment pattern with different ratio of sensing radius and communication radius. This paper also analyses the average time delay during which the base station can collect all the data from the target area. The simulations show that MSSDB needs the least number of sensors compared to the existing classic algorithms. And the information collected from the target area could reach the base station within a fixed time constraint.For the problem of minimum sensor coverage satisfying partially connectivity, this paper proposes a node selection algorithm based on Connect Road Gain(SSCG). SSCG converts the area coverage to the target coverage. It greedily selects the sensors who cover the most target points and adds the sensor to the resulting set. This step continues until the resulting set can cover the entire target area. Then it judges if every sensor node in the resulting set can find a communication path to the road, if not, it continues to add the sensors to the resulting sets depend on the value of Connect Road Gain. The sensor which has the largest ConnectRoad Gain is added to the resulting set every step until every sensor node in the resulting set can find a communication path to the road. Finally, the resulting set that can coverage the target area and satisfy partially connectivity is obtained. The simulations show that when the communication radius is not larger than twice the sensing radius the algorithm proposed by this paper SSCG can save a lot sensors compared to the existing algorithms that satisfying coverage and global connectivity C BA. When the communication radius is much larger than the sensing radius, SSCG is not better than CBA. When the node density of the WSNs is large, the advantage of SSCG is obvious, but when the WSNs are sparse, both SSCG and CBA get a poor performance.