A Virtual Node-Based Flash Crowds Alleviation Method for Sensor Overlay Networks

The rapid development of sensor networks has made it possible to build large-scale sensor overlay networks by integrating separated sensing resources. As the overlay substrate of sensor overlay networks, range queriable P2Ps such as Skip Graph are often applied since they enable retrieving sensing resources whose properties are within the specified range in an effective and scalable way. The range queriable P2P-based sensor overlay networks have proven to be effective in many scenarios, however, the sensor overlay nodes will suffer from flash crowds of queries when disasters, accidents or some events happen. In this paper, we present a virtual node-based approach to alleviate flash crowds for sensor overlay networks. In our approach, a hot-spot node can ask physically spare nodes located in any where in the overlay to generate virtual nodes with the same key as itself, and make the virtual nodes join the overlay network as if they were normal nodes around the hot-spot. With this method, both the query service load of the hot-spot node and the query routing load of the nearby nodes of the hot-spot node can be well distributed with low cost. With theoretical analysis and simulations, we show that our method is efficient, feasible and scalable.