39:16·N.Yu et al. 1 ☐Lagest-.Pc 08 lom-PCI PCA 0.4 -Largest-PCI 02 om-PCI PCA 3 透56 7 8 9 10 10 Measurement error(cm) Pushing distance(cm) (a)CDF of pushing 40 cm (b)Average measurement error Fig.12.Distance measurement accuracy. -Ground truth -Person A erson B Person C Person D ◆Person E 90 100 105 110 115 120 02 0.3 0.4 05 0. 0.7 0.8 09 X(cm Time (seconds) Fig.13.Example of tracking result. Fig.14.Movement direction accuracy. 8 62 -30 degree -45 degree -60 deoree I -90 degree 0 45 0 Direction Emor(degrees) Horizontal angle(degrees) (a)CDF of absolute direction error (b)Average measurement error for different directions. Fig.15.2D tracking results. Figure 16(b)shows the distance measurement accuracy for pushing distance of 40 cm with different Du,the dis- tance between the user and the receiver,while D:is fixed at 1 meter.We observe that the measurement accuracy decreases when Du increases and at a distance of 2.5 meters the error of both PCI and PCA is larger than 10 cm As Du increases,the performance of PCI decreases quickly,while PCA can achieve less than 4 cm error when the hand is at 2 meters.This shows PCA works better than PCI on weak signals. QGesture achieves measurement error smaller than 2.7 cm where there is no LOS between the transmitter and receiver.Figure 16(c)shows how the CSI variations changes with increasing distance between transmitter and receiver(D,in Figure 11(b)).We observe that the amplitude only slightly decreases when the distance between transmitter and receiver increases.This indicates that the amplitude of the reflection is mainly determined by the distance between the reflector to the receiver.Figure 16(d)shows the distance measurement error with different Proceedings of the ACM on Human-Computer Interaction,Vol.1,No.4.Article 39.Publication date:March 2018.39:16 • N. Yu et al. 0 1 2 3 4 5 6 7 8 9 10 Measurement error (cm) 0 0.2 0.4 0.6 0.8 1 CDF Largest-PCI Random-PCI PCA (a) CDF of pushing 40 cm. 10 20 30 40 Pushing distance (cm) 0 2 4 6 8 10 12 Measurement error (cm) Lagest-PCI Random-PCI PCA (b) Average measurement error. Fig. 12. Distance measurement accuracy. 85 90 95 100 105 110 115 120 X (cm) -100 -90 -80 -70 -60 Y (cm) Tracking result Ground truth Fig. 13. Example of tracking result. 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Time (seconds) 80 85 90 95 100 Accuray (%) Person A Person B Person C Person D Person E Fig. 14. Movement direction accuracy. 0 10 20 30 40 Direction Error (degrees) 0 0.2 0.4 0.6 0.8 1 CDF 30 degree 45 degree 60 degree 90 degree (a) CDF of absolute direction error. 30 45 60 90 Horizontal angle (degrees) 0 1 2 3 4 5 Measurement error(cm) (b) Average measurement error for different directions. Fig. 15. 2D tracking results. Figure 16(b) shows the distance measurement accuracy for pushing distance of 40 cm with different Du , the dis￾tance between the user and the receiver, while Dt is fixed at 1 meter. We observe that the measurement accuracy decreases when Du increases and at a distance of 2.5 meters the error of both PCI and PCA is larger than 10 cm. As Du increases, the performance of PCI decreases quickly, while PCA can achieve less than 4 cm error when the hand is at 2 meters. This shows PCA works better than PCI on weak signals. QGesture achieves measurement error smaller than 2.7 cm where there is no LOS between the transmitter and receiver. Figure 16(c) shows how the CSI variations changes with increasing distance between transmitter and receiver (Dt in Figure 11(b)). We observe that the amplitude only slightly decreases when the distance between transmitter and receiver increases. This indicates that the amplitude of the reflection is mainly determined by the distance between the reflector to the receiver. Figure 16(d) shows the distance measurement error with different Proceedings of the ACM on Human-Computer Interaction, Vol. 1, No. 4, Article 39. Publication date: March 2018