Plausibility of practical low-cost location using WSN path-loss law inversion

The plausibility of using received signal strength indication (RSSI), as typically provided by receiving nodes of simple first-generation wireless sensor network technologies, for location of slow moving objects is tested experimentally in an open, flat, outdoor environment. The tests carried out use nodes operating to the IEEE 802.15.4 standard. The accuracy of a simple two-ray propagation model, appropriate to the open, flat, nature of the test area is investigated and an RSSI versus distance model is derived. The accuracy of a simple trilateration location algorithm based on an inversion of the path-loss model is then tested. Such a system is found to be plausible for applications requiring only modest location accuracies (within a few metres) and modest coverage (100s of metres).