Juhua Pu

A Localized Coverage Preserving Protocol for Wireless Sensor Networks

In a randomly deployed and large scale wireless sensor network, coverage-redundant nodes consume much unnecessary energy. As a result, turning off these redundant nodes can prolong the network lifetime, while maintaining the degree of sensing coverage with a limited number of on-duty nodes. None of the off-duty eligibility rules in the literature, however, are sufficient and necessary conditions for eligible nodes. Hence redundancy or blind points might be incurred. In this paper we propose a complete Eligibility Rule based on Perimeter Coverage (ERPC) for a node to determine its eligibility for sleeping. ERPC has a computational complexity of O(N2log(N)), lower than the eligibility rule in the Coverage Control Protocol (CCP), O(N3), where N is the number of neighboring nodes. We then present a Coverage Preserving Protocol (CPP) to schedule the work state of eligible nodes. The main advantage of CPP over the Ottawa protocol lies in its ability to configure the network to any specific coverage degree, while the Ottawa protocol does not support different coverage configuration. Moreover, as a localized protocol, CPP has better adaptability to dynamic topologies than centralized protocols. Simulation results indicate that CPP can preserve network coverage with fewer active nodes than the Ottawa protocol. In addition, CPP is capable of identifying all the eligible nodes exactly while the CCP protocol might result in blind points due to error decisions. Quantitative analysis and experiments demonstrate that CPP can extend the network lifetime significantly while maintaining a given coverage degree.

A Robust Routing Algorithm with Fair Congestion Control in Wireless Sensor Network

There has been a growing interest in wireless sensor networks (WSNs). Considering the limited energy, memory and computational capacity of the sensor nodes, it becomes necessary to ensure rational use of their resources. The fairness and congestion control are also need to be taken into account. It is in this context that a robust routing algorithm with fair congestion control in wireless sensor network (called RRA- FCC) is proposed. RRA-FCC performs a low cost and robust routing based on dividing the monitoring region into several subareas initially. Furthermore, RRA-FCC provides a fair congestion control, which improves the whole network fairness in congestion. The simulation results show that RRA-FCC performs well in the throughput of Sink nodes, energy consumption and the whole network fairness in congestion.

Issue and solution on coverage and performance for wireless sensor networks

To reduce energy consumption and extend lifetime is concernful in wireless sensor networks (WSNs). Besides, WSNs need to maintain coverage quality to capture the timely changed targets. A broad strategy is to select some sensors as working nodes to cover the monitored region while turning off redundant nodes. Therefore, scheduling node state and maintaining the coverage quality are two important aspects in WSNs. The contribution lies in two aspects in this paper. First, we present a mathematical model to compute minimum number of nodes under any given required coverage quality. Simulation results demonstrate that our approach is more accurate when the ratio of target region to sensor region is larger, and the complexity of proposed method is lower while the sensors region can be perceived as arbitrary shape. Second, it is an NP-hard issue that networks coverage quality and ratio of sleeping nodes get to maximize together. The paper experiments by using genetic algorithm to try to solve this problem, which is significant in WSNs for practical applications.