VBS: Maximum Lifetime Sleep Scheduling for Wireless Sensor Networks Using Virtual Backbones

Wireless sensor network (WSN) applications require redundant sensors to guarantee fault tolerance. However, the same degree of redundancy is not necessary for multi-hop communication. In this paper, we present a new scheduling method called virtual backbone scheduling (VBS). VBS employs heterogeneous scheduling, where backbone nodes work with duty-cycling to preserve network connectivity, and non-backbone nodes turn off radios to save energy. We formulate a maximum lifetime backbone scheduling (MLBS) problem to maximize the network lifetime using this scheduling model. Because the MLBS problem is NP-hard, two approximation solutions based on the schedule transition graph (STG) and virtual scheduling graph (VSG) are proposed.We also present an iterative local replacement (ILR) scheme as an distributed implementation of VBS. The path stretch problem is analyzed in order to explore the impact of VBS on the network structure. We show, through simulations, that VBS significantly prolongs the network lifetime under extensive conditions.