Connectivity maintenance and coverage preservation in wireless sensor networks

In wireless sensor networks, one of the main design challenges is to obtain long system lifetime. Letting sensors work alternatively by identifying redundant nodes in high-density networks is believed to be one potential solution. In wireless sensor networks, there might exist two kinds of redundancy, sensing and communication. Most previous work has addressed just one kind of redundancy. H. Zhang and J.C. Hou (see Technical Report UIUCDCS-R-2003-2351, 2003) first discussed how to combine considerations of coverage and connectivity maintenance in a single activity scheduling. However, they just provided the theoretical basis for safe integration in fully covered networks. Considering the initial sensing holes due to random node deployment, we enhance their work by providing the following proof: "the communication range is twice the size of the sensing range" is the sufficient condition and tight lower bound to ensure that complete coverage preservation implies connectivity among active nodes if the original network topology is connected.