Conclusion
Connectivity and coverage are two of the most important issues in WSNs, which can be considered as the sufficient conditions to utilize a WSN. Many research efforts have been proposed to cope with these problems. In this survey, firstly, we briefly introduced the basic knowledge on the notions of connectivity and coverage. Then, we summarized the research efforts proposed for addressing the connectivity problem, and then listed the critical conditions to keep system connectivity. Since the connectivity is affected by the node/link failures, we also did a survey for the research work related to the failure-resilient/fault-tolerant WSNs design problem. Further, we summarized the existing approaches addressed integrated connectivity and coverage problem. Based on the proposed conditions for keeping connectivity while preserving coverage, we described the research efforts proposed for coverage problem in the final.
