Scalability of Time Synchronized wireless sensor networking

Existing commercial wireless sensor network solutions use Time-Synchronized Channel Hopping (TSCH) to achieve an end-to-end reliability higher than 99.9% and industry-accepted network lifetime (5-10 years on batteries). In these types of networks, once nodes synchronize, they follow a schedule which determines the time and frequency of the channel that is used to transmit and receive. Standards such as WirelessHART apply this technique. This paper addresses the ability to scale such a scheduling approach for specific applications. Specifically, this paper demonstrates the ability to create a successful schedule for a network consisting of 10,000 nodes within a 0.1 km² area, an equivalent density to one million nodes, deployed in a 10 km² area. Each node reports a sampled measurement every 10s. Such environmental requirements are common for industrial plants, where individual elements are equipped with various sensors (e.g., vibration, pressure, temperature, flow, tank level and corrosion). Given these typical network densities and empirical propagation models, we develop a targeted open-source end-to-end network and packet simulator to model mote position, connectivity and routing to create a schedule which yields collision-free network operation. We show that such a schedule can be built, and determine the minimal number of sink nodes needed in such a network. The schedule is verified by packet flow simulation to assess expected packet reliability, delay and power consumption.