Variable weight code division multiple access system for monitoring vibration of unequally distributed points

The ever-growing demand for more accurate structural health monitoring of large scale facilities such as modern high-speed railways and bridges have resulted in the development of optical sensor networks (OSN), which help eliminate the disadvantages of conventional electric sensors, the most significant of which are sensitivity to electromagnetic interferences and larger sizes. The existing fibre optic infrastructures that are implanted mainly for communication purposes are not widely used by OSNs, due to the lack of appropriate multiplexing techniques. This study proposes an optical code division multiple access (OCDMA) system for support vibration sensing of unequally distributed points. The proposed system takes the advantages of spectral amplitude encoding (SAC) technique in providing differentiated services in physical layer by varying code weights. Simulation results monitoring three vibration sensor nodes with different distances are presented in the paper. The simulation and mathematical analysis indicate the suitability and simple implementation of the proposed system for supporting vibration sensing with high accuracy.