Energy-efficient data preservation in intermittently connected sensor networks

We study data preservation in intermittently connected sensor networks, wherein the sensor nodes do not always have connected paths to the base station. In such networks, the generated data is first stored inside the network before being uploaded to the base station when uploading opportunity arises. How to preserve the data inside the network is therefore an important problem. The problem becomes more challenging when sensor nodes have finite and unreplenishable battery energy. In this paper, we identify, formulate and study the data preservation problem in the intermittently connected sensor networks under energy constraints at sensor nodes. The problem aims to preserve the data inside the network for maximum possible time, by distributing the data items from low energy nodes to high energy nodes. We first show that this problem is NP-hard. We then design a centralized greedy heuristic and a distributed data distribution algorithm, and compare their performances using simulations.