Characterization of Discrimination of Number of Signal Collision Sensors Using Spectral Fluctuation Caused by Frequency Offset in Physical Wireless Parameter Conversion Sensor Networks

Physical Wireless Parameter Conversion Sensor Networks (PhyC-SN) is converts sensor information into a carrier wave and transmits it to aggregate information from many sensors at a high speed. The authors established a method to detect multiple sensors accessing within a specific frequency by utilizing frequency offsets to check whether the signals of multiple sensors collide within the frequency. However, it is difficult to identify the number of sensors accessing at the same time. In this study, we established a method to use fluctuations in the received energy spectrum due to sensor-specific frequency offsets as a feature to identify the number of sensors and clarified the identification accuracy for up to four transmitting sensors.