Range-free algorithm for energy-efficient indoor localization in Wireless Sensor Networks

Wireless Sensor Networks (WSNs) form an attractive technology for ubiquitous indoor localization. The localized node lifetime is maximized by using energy-efficient radios and minimizing their active time. However, the most low-cost and low-power radios do not include Received Signal Strength Indicator (RSSI) functionality commonly used for RF-based localization. In this paper, we present a range-free localization algorithm for localized nodes with minimized radio communication and radios without RSSI. The low complexity of the algorithm enables implementation in resource-constrained hardware for in-network localization. We experimented the algorithm using a real WSN implementation. In room-level localization, the area was resolved correctly 96% of the time. The maximum point-based error was 8.70 m. The corresponding values for sub-room-level localization are 100% and 4.20 m. The prototype implementation consumed 1900 B of program memory. The data memory consumption varied from 18 B to 180 B, and the power consumption from 345 μW to 2.48 mW depending on the amount of localization data.