This article has been accepted for inclusion in a future issue of this journal.Content is final as presented,with the exception of pagination IEEE/ACM TRANSACTIONS ON NETWORKING [16]L.Shangguan and K.Jamieson,"The design and implementation of Chuyu Wang received the B.S.degree in software a mobile RFID tag sorting robot,"in Proc.ACM MobiSys,2016. engineering from the Dalian University of Tech- Pp.31-42 nology,China,in 2012.He is currently pursuing [17]L.Xie,J.Sun,Q.Cai,C.Wang.J.Wu,and S.Lu,"Tell me what I see: the Ph.D.degree with the Department of Computer Recognize RFID tagged objects in augmented reality systems,"in Proc. Science and Technology,Nanjing University.His ACM UbiComp.2016.pp.916-927. research interests include RFID systems and indoor [18]T.Liu,L.Yang,Q.Lin,Y.Guo,and Y.Liu,"Anchor-free backscat- localization. ter positioning for RFID tags with high accuracy,"in Proc.IEEE NF0C0M,Apr.2014,pp.379-387. [19]C.Wang.L.Xie,W.Wang.T.Xue,and S.Lu,"Moving tag detection via physical layer analysis for large-scale RFID systems,"in Proc.IEEE INFOCOM,Apr.2016,pp.1-9. [20]J.Liu,M.Chen,S.Chen,Q.Pan,and L.Chen,"Tag-compass: Determining the spatial direction of an object with small dimensions," in Proc.IEEE INFOCOM,May 2017.pp.1-9. [21]J.Liu et al.."RF-scanner:Shelf scanning with robot-assisted RFID Alex X.Liu received the Ph.D.degree in computer systems,"in Proc.IEEE INFOCOM,May 2017,pp.1-9. science from The University of Texas at Austin [22]L.Shangguan,Z.Yang.A.X.Liu,Z.Zhou,and Y.Liu,"STPP: in 2006.He is currently with the Department of Spatial-temporal phase profiling-based method for relative RFID tag Computer Science and Engineering.Michigan State localization,"IEEE/ACM Trans.Nenw.,vol.25,no.1,pp.596-609. University,East Lansing,MI,USA,and with the Feb.2017. [23]Q.Pu,S.Gupta,S.Gollakota,and S.Patel,"Whole-home gesture State Key Laboratory for Novel Software Tech- nology,Nanjing University,Nanjing,China.His recognition using wireless signals,"in Proc.ACM MobiCom,2013. research interests include networking and security. pp.27-38. He received the IEEE and IFIP William C.Carter [24]G.Wang.Y.Zou,Z.Zhou,K.Wu.and L.M.Ni,"We can hear you with Wi-Fi!"in Proc.ACM MobiCom,2014.pp.593-604. Award in 2004,the National Science Foundation CAREER Award in 2009.and the Michigan State [25]B.Kellogg,V.Talla,and S.Gollakota,"Bringing gesture recognition to University Withrow Distinguished Scholar Award in 2011.He also received all devices,"in Proc.NSDI,2014,pp.303-316. the Best Paper Awards from ICNP-2012,SRDS-2012,and LISA-2010.He is [26]Y.Liu,L.Chen,J.Pei,Q.Chen,and Y.Zhao,"Mining frequent an Associate Editor of the IEEE/ACM TRANSACTIONS ON NETWORKING. trajectory patterns for activity monitoring using radio frequency tag an Associate Editor of the IEEE TRANSACTIONS ON DEPENDABLE AND arrays,"in Proc.PERCOM,2007,pp.37-46. [27]J.Han et al.,"Twins:Device-free object tracking using passive tags," SECURE COMPUTING,and an Area Editor of Computer Communications. IEEE/ACM Trans.Nerw..vol.24.no.3.pp.1605-1617.Jun.2016. [28]L.Yang,Q.Lin,X.Li,T.Liu,and Y.Liu,"See through walls with cots RFID system!"in Proc.MobiCom,2015,pp.487-499. [29]Q.Lin et al.."Beyond one-dollar mouse:A battery-free device for 3D human-computer interaction via RFID tags,"in Proc.IEEE INFOCOM. Apr.2015,Pp.1661-1669. Jiangiang Sun received the B.S.degree in infor- [30]J.Han et al.,"CBID:A customer behavior identification system using mation security from Nanjing Normal University. passive tags."IEEE/ACM Trans.Nerw.,vol.24.no.5.pp.2885-2898. China,in 2011,and the M.S.degree from the 0ct.2016. Department of Computer Science and Technology, [31]H.Ding et al.."FEMO:A platform for free-weight exercise monitoring Nanjing University,in 2016.His research interests with RFIDs."in Proc.ACM SenSys,2015.pp.141-154. include RFID systems and Internet of Things. [32]D.Zhang.J.Zhou,M.Guo,J.Cao.and T.Li."TASA:Tag-free activity sensing using RFID tag arrays,"IEEE Trans.Parallel Distrib.Syst., vol.22,no.4,Pp.558-570,Apr.2011. [33]D.E.Knuth,J.H.Morris,Jr.,and V.R.Pratt,"Fast pattern matching in strings"SIAM J.Comput..vol.6,no.2.pp.323-350.1977. [34]ImpinJ.(2016).[Online].Available:http://www.impinj.com Lei Xie received the B.S.and Ph.D.degrees in computer science from Nanjing University,China. Sanglu Lu received the B.S.,M.S.,and Ph.D. in 2004 and 2010.respectively.He is currently an degrees in computer science from Nanjing Univer- Associate Professor with the Department of Com- sity,China,in 1992,1995.and 1997.respectively. puter Science and Technology,Nanjing University. She is currently a Professor with the Department He has authored or coauthored over 50 papers in the IEEE TRANSACTIONS ON MOBILE COMPUT- of Computer Science and Technology.Nanjing Uni- versity.Her research interests include distributed ING.the IEEE TRANSACTIONS ON PARALLEL AND computing and pervasive computing. DISTRIBUTED SYSTEMS,the ACM Transactions on Sensor Nenworks,the ACM UbiComp.the ACM MobiHoc,the IEEE INFOCOM.the IEEE ICNP.and the IEEE ICDCS.This article has been accepted for inclusion in a future issue of this journal. Content is final as presented, with the exception of pagination. 14 IEEE/ACM TRANSACTIONS ON NETWORKING [16] L. Shangguan and K. Jamieson, “The design and implementation of a mobile RFID tag sorting robot,” in Proc. ACM MobiSys, 2016, pp. 31–42. [17] L. Xie, J. Sun, Q. Cai, C. Wang, J. Wu, and S. Lu, “Tell me what I see: Recognize RFID tagged objects in augmented reality systems,” in Proc. ACM UbiComp, 2016, pp. 916–927. [18] T. Liu, L. Yang, Q. Lin, Y. Guo, and Y. Liu, “Anchor-free backscat￾ter positioning for RFID tags with high accuracy,” in Proc. IEEE INFOCOM, Apr. 2014, pp. 379–387. [19] C. Wang, L. Xie, W. Wang, T. Xue, and S. Lu, “Moving tag detection via physical layer analysis for large-scale RFID systems,” in Proc. IEEE INFOCOM, Apr. 2016, pp. 1–9. [20] J. Liu, M. Chen, S. Chen, Q. Pan, and L. Chen, “Tag-compass: Determining the spatial direction of an object with small dimensions,” in Proc. IEEE INFOCOM, May 2017, pp. 1–9. [21] J. Liu et al., “RF-scanner: Shelf scanning with robot-assisted RFID systems,” in Proc. IEEE INFOCOM, May 2017, pp. 1–9. [22] L. Shangguan, Z. Yang, A. X. Liu, Z. Zhou, and Y. Liu, “STPP: Spatial-temporal phase profiling-based method for relative RFID tag localization,” IEEE/ACM Trans. Netw., vol. 25, no. 1, pp. 596–609, Feb. 2017. [23] Q. Pu, S. Gupta, S. Gollakota, and S. Patel, “Whole-home gesture recognition using wireless signals,” in Proc. ACM MobiCom, 2013, pp. 27–38. [24] G. Wang, Y. Zou, Z. Zhou, K. Wu, and L. M. Ni, “We can hear you with Wi-Fi!” in Proc. ACM MobiCom, 2014, pp. 593–604. [25] B. Kellogg, V. Talla, and S. Gollakota, “Bringing gesture recognition to all devices,” in Proc. NSDI, 2014, pp. 303–316. [26] Y. Liu, L. Chen, J. Pei, Q. Chen, and Y. Zhao, “Mining frequent trajectory patterns for activity monitoring using radio frequency tag arrays,” in Proc. PERCOM, 2007, pp. 37–46. [27] J. Han et al., “Twins: Device-free object tracking using passive tags,” IEEE/ACM Trans. Netw., vol. 24, no. 3, pp. 1605–1617, Jun. 2016. [28] L. Yang, Q. Lin, X. Li, T. Liu, and Y. Liu, “See through walls with cots RFID system!” in Proc. MobiCom, 2015, pp. 487–499. [29] Q. Lin et al., “Beyond one-dollar mouse: A battery-free device for 3D human-computer interaction via RFID tags,” in Proc. IEEE INFOCOM, Apr. 2015, pp. 1661–1669. [30] J. Han et al., “CBID: A customer behavior identification system using passive tags,” IEEE/ACM Trans. Netw., vol. 24, no. 5, pp. 2885–2898, Oct. 2016. [31] H. Ding et al., “FEMO: A platform for free-weight exercise monitoring with RFIDs,” in Proc. ACM SenSys, 2015, pp. 141–154. [32] D. Zhang, J. Zhou, M. Guo, J. Cao, and T. Li, “TASA: Tag-free activity sensing using RFID tag arrays,” IEEE Trans. Parallel Distrib. Syst., vol. 22, no. 4, pp. 558–570, Apr. 2011. [33] D. E. Knuth, J. H. Morris, Jr., and V. R. Pratt, “Fast pattern matching in strings,” SIAM J. Comput., vol. 6, no. 2, pp. 323–350, 1977. [34] ImpinJ. (2016). [Online]. Available: http://www.impinj.com Lei Xie received the B.S. and Ph.D. degrees in computer science from Nanjing University, China, in 2004 and 2010, respectively. He is currently an Associate Professor with the Department of Com￾puter Science and Technology, Nanjing University. He has authored or coauthored over 50 papers in the IEEE TRANSACTIONS ON MOBILE COMPUT￾ING, the IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS, the ACM Transactions on Sensor Networks, the ACM UbiComp, the ACM MobiHoc, the IEEE INFOCOM, the IEEE ICNP, and the IEEE ICDCS. Chuyu Wang received the B.S. degree in software engineering from the Dalian University of Tech￾nology, China, in 2012. He is currently pursuing the Ph.D. degree with the Department of Computer Science and Technology, Nanjing University. His research interests include RFID systems and indoor localization. Alex X. Liu received the Ph.D. degree in computer science from The University of Texas at Austin in 2006. He is currently with the Department of Computer Science and Engineering, Michigan State University, East Lansing, MI, USA, and with the State Key Laboratory for Novel Software Tech￾nology, Nanjing University, Nanjing, China. His research interests include networking and security. He received the IEEE and IFIP William C. Carter Award in 2004, the National Science Foundation CAREER Award in 2009, and the Michigan State University Withrow Distinguished Scholar Award in 2011. He also received the Best Paper Awards from ICNP-2012, SRDS-2012, and LISA-2010. He is an Associate Editor of the IEEE/ACM TRANSACTIONS ON NETWORKING, an Associate Editor of the IEEE TRANSACTIONS ON DEPENDABLE AND SECURE COMPUTING, and an Area Editor of Computer Communications. Jianqiang Sun received the B.S. degree in infor￾mation security from Nanjing Normal University, China, in 2011, and the M.S. degree from the Department of Computer Science and Technology, Nanjing University, in 2016. His research interests include RFID systems and Internet of Things. Sanglu Lu received the B.S., M.S., and Ph.D. degrees in computer science from Nanjing Univer￾sity, China, in 1992, 1995, and 1997, respectively. She is currently a Professor with the Department of Computer Science and Technology, Nanjing Uni￾versity. Her research interests include distributed computing and pervasive computing