Smooth path construction and adjustment for multiple mobile sinks in wireless sensor networks

Wireless multimedia sensor networks can provide a much clearer picture of the sensed area and thus significantly improve many applications. However, the increased amount of data will lead to issues with energy consumption and network lifetimes if we use the traditional network-based data collection where packets are forwarded hop by hop to the base. To mitigate these problems, researchers have been investigating mobile sinks traveling through the network and collecting the generated data. Using mobile sinks significantly increases the delivery rate while also reducing energy usage, but this increases the collection delay because of the physical speed of mobile sinks. In this paper, to reduce the physical collection delay while maintaining the other performance improvements (e.g., delivery rate, energy usage), we focus on how to use faster mobile sinks. Such mobile sinks are often motion-constrained and require smooth paths which can be followed with these constraints. Accordingly, we first developed a basic smooth path construction algorithm based on the TSP. We then extended it with path adjustments based on the required contact time at each node. Finally, we allowed for multiple mobile sinks which allowed us to further reduce the average delay per packet over the previous algorithms. Through extensive simulations, we found our algorithm allows for faster data collection over the current solutions, which can only accommodate flexible but slower mobile sinks, while maintaining the increased delivery rate and decreased energy usage.