Dynamic threshold adjustment in a proximity-based location tracking system using reference modules

In recent years, location tracking systems have become important in areas such as transportation, shopping, logistics and medicine. One of the most recent approaches are proximity-based location tracking systems, which use the received signal strength (RSSI) measured between a sender and an anchor module. The advantages of these systems are high scalability, minimal calibration effort and low costs. However, there are also disadvantages e.g. the fluctuating signal strength under certain circumstances in the environment. To detect, if an object has entered a predefined region, the RSSI must exceed a specified threshold. When the current signal fluctuates due to obstacles (other objects, people, etc.) the static threshold does not apply for the defined region any longer. In this case automatic adjustments of the threshold are made with the help of a reference module. Various factors are measured between reference, anchor as well as a sender module and subsequently used to correct the static threshold. The dynamic adjustment was tested through three experiments and showed satisfactory results concerning the hypotheses. For further research, additional factors might need to be included to make the proposed method more dynamic and responsive to the environment.