Table 5.

Summary of the reviewed baseline-based methods

Ref.	Approach	Main contribution
[96]	piUSBL	Accurate positioning with inexpensive, low-power, and lightweight equipment
[97]	iUSBL-SLAM and UKF	High positioning performance in sparse beacons environments
[134]	USBL time-delay estimation algorithm	High accuracy of TOF and TOA estimation in sound source navigation
[99]	LBL smooth optimizing algorithm	Long-range high accurate positioning performance
[100]	USBL and neural network	High positioning performance in low-SNR regions

piUSBL, Passive Inverted USBL; iUSBL, Inverted USBL; UKF, Unscented Kalman Filter; USBL, Ultra-Short Baseline; LBL, Long Baseline.