Fig. 1. Positioning system model

Fig. 2. Specific layout with boundary correction

Fig. 3. Distribution of three-dimensional positioning with ELM

Fig. 4. CDF of positioing error at the heights of 0,0.3,0.6,0.9 m

Fig. 5. CDF of positioing error under different signal-to-noise ratios

Fig. 6. CDF of simulation positioning error under the sparse samples with the number of 32,40,48,56,64

Fig. 7. CDF of simulation positioning error with adding 4 virtual nodes

Fig. 8. CDF of simulation positioning error with adding 8 virtual nodes

Fig. 9. Positioning error distribution with x, y, z axes. (a) 32 samples; (b)40 samples; (c) 48 samples; (d) 56 samples

Fig. 10. CDF of simulation positioning error with RF, KNN, BP, ELM, and SRoFM-LwBC, respectively

Fig. 11. Location distribution of estimated targets with ELM and SRoFM-LwBC, respectively

Fig. 12. Specific experimental layout under the visible light scene

Fig. 13. CDF comparison of experimental positioning error under sparse samples with SRoFM(The dotted lines are the simulation results, the solid lines are the experimental results)

Fig. 14. CDF comparison of experimental positioning error under sparse samples by introducing LwBC

Fig. 15. Positioning error distribution of x, y, z axes. (a) 40 samples; (b) 48 samples; (c) 56 samples