A multi-channel wireless connection system for structural health monitoring applications

To overcome the drawbacks related to a wired solution for structural health monitoring applications, many kinds of wireless sensors have been proposed and prototyped. Most of these sensors are of the single channel type. Multi-channel solutions also exist and they are mainly based on time-division multiplexing (TDM). Both these types of wireless communication systems cause large time delays when a large number of sensors nodes are deployed. In this paper, a different multi-channel wireless sensor solution, based on a mixed approach that exploits both TDM and frequency-division multiplexing (FDM), is introduced. As a result, the time delay is independent of the number of sensor nodes. The real-time multi-channel feature represents a key aspect of the proposed wireless sensing network. The wireless scheme is initially intended a simple solution for analog cable replacement and it is preliminarily tested in a laboratory environment. The powerful and flexible system-on-chip single-chip wireless transceiver, which can operate in the Industrial, scientific and medical (ISM) license-free frequency bands, is employed to perform both the control function and the wireless communication. The goal is to reach a good balance among communication range, power consumption, data rate, and link quality. The overall design, the implementation, and an experimental validation of the proposed multi-channel wireless sensor solution are presented.