How Acquired Log-Distance Path-Loss Equations Affect the Accuracy of Lateration and WCL Methods: An Experimental Comparison

• Published in: Journal of electrical engineering & technology Vol. 18; no. 1; pp. 599 - 614
• Main Authors: Wattananavin, Thradon, Auysakul, Jutamanee, Tanthanuch, Sawit, Buranapanichkit, Dujdow, Sengchuai, Kiattisak, Jindapetch, Nattha, Booranawong, Apidet
• Format: Journal Article
• Language: English
• Published: Singapore Springer Nature Singapore 2023; 대한전기학회
• Subjects: Electrical Engineering; Electrical Machines and Networks; Electronics and Microelectronics; Engineering; Instrumentation; Original Article; Power Electronics; 전기공학; WCL; Path-loss equation; RSSI-based localization; Lateration; Experiment
• ISSN: 1975-0102; 2093-7423
• DOI: 10.1007/s42835-022-01188-y

In the well-known and widely used lateration and weighted centroid localization (WCL) methods, as received signal strength indicator (RSSI) based methods, the position of an unknown target is estimated by using the reference node positions and RSSI levels, which represent the distances between the target and the reference nodes. Since the path-loss equation determined by the test environment is used to convert the RSSI level to the distance value, it can influence the performance of the RSSI-based methods. In this paper, first, we provide the theoretical calculation that demonstrates the accuracy of the lateration and the WCL when the effect of radio signals or the path-loss equation is not taken into consideration (i.e., actual distances are directly used for position estimation). Theoretical results show that the lateration estimates the unknown target position without any error, while the WCL produces an error of 0.407 m with a SD of 0.244 in our scenario, which corresponds to a real test. Then, the experimental evaluation of the effects of different log-distance path-loss equations (with different path-loss exponents) on the accuracy of both methods is investigated, where log-distance path-loss equations of the test environment are obtained by using measured RSSI data from different transmitter and receiver directions. Experiments using a 2.4 GHz IEEE 802.15.4/ZigBee wireless network with four reference nodes have been carried out in a laboratory. Experimental results reveal that different log-distance path-loss equations significantly affect the lateration accuracy. Average estimation errors in this case can vary from 0.360 to 1.603 m. Our findings indicate that, using the lateration, it is very important to find and select the optimal path-loss exponent to achieve the best localization accuracy. For the WCL method, average errors are not significantly different. They varied from 0.410 to 0.485 m (a minor change). Here, the experiment reveals that the WCL can tolerate different path-loss equation effects.