物聯網是最近這幾年最新興的話題。不久的未來，物聯網將讓所有能夠被獨立尋址的普通物理物件連上虛擬的網路世界。如果我們可以同時在現實世界鎖定實體物品的位子並且在虛擬世界也定義它，這將是非常有用的發展。然而想要在室內環境精確定位出目標物，相當不容易。一方面因為電磁波在室內傳播常會碰到多路徑反射的干擾，會造成定位上嚴重的誤差。另一方面是傳統主動式定位系統通常要求，在每一個目標物都裝上收發機等待接收或是回傳資料，其總體功率消耗相當可觀，所以本論文中提出基於被動式無線辨識技術之室內定位系統，成功解決兩個技術上最重要的問題。

被動式無線射頻辨識晶片因為擁有低功耗、低成本的好處，所以將會成為室內定位系統的首選。我們第一個設計，提出一個雙通道15-bit CMOS超高頻被動式無線射頻辨識標籤晶片的原型，它運作的靈敏度可以低於--20 dBm。其效果遠超過先前的研究資料量測結果顯示，我們所提出的被動式標籤晶片的靈敏度可以降到 --21.2 dBm。當讀取器等效全向輻射功率發射(EIRP)為36 dBm，且標籤晶片有0.4 dBi的增益時。可以推算出讀取器與標籤晶片的可讀取距離是19.6 m。實現遠距讀取的功能

擁有可以遠距讀取的雙頻帶標籤晶片之後，我們提出一個新型的室內定位系統。此系統藉由機率統計的演算法降低定位錯誤率。總體系統定位累加機率錯誤率是87.5\% 。系統射頻部分的總功率消耗是24.63 dBm，與之前的文獻的比較是目前最低的功率消耗。本系統另外一個優點是可以很容易延展成一個大系統。

Internet of Things (IoT) is an emerging topic of research recently. In the future, all things in the real world will connect to the virtual world. It will be useful if we can locate an object in the real world as well as identify it in the virtual world. However, it is not easy to accurately position a target in the indoor environment. For one thing, the radio waves propagate in an indoor environment is affected by multipath interference. It makes serious estimation errors when the target is positioned. For another, when each target has a transceiver the overall power consumption of the whole system is considerable. In this work, a passive RFID system is proposed to solve the two important technological problems.

Because the passive RFID has the advantages of low power consumption and low cost, it has become a preferred wireless technology for indoor positioning system in recent years. we first design a dual-channel 15-bit UHF passive CMOS RFID tag prototype that can work at sensitivity lower than --20 dBm. Measurement result shows that the sensitivity of the proposed passive tag chip can reach down to --21.2 dBm. Such result corresponds to a 19.6-m reader-to-tag distance under 36-dBm EIRP and 0.4-dBi tag antenna. It provides the long-range tag for our system.

Having the long-range dual-band tag, we propose a novel indoor positioning system. The proposed indoor positioning system employs a probabilistic algorithm to reduce the positioning error. The cumulative probability for positioning error within is 87.5\%. The power consumption of the RF part of the proposed system is 24.63 dBm, which is the lowest compared with the prior art. Furthermore, the proposed system can be easily expanded a larger system.

References
[1] Industrial Taiwan Research Institute. (2014, Oct.) [Online]. Available: http://cloudcomputing.sys-con.com/node/1330353.
[2] Hui Liu, Darabi, H., Banerjee P., Jing Liu, “Survey of Wireless Indoor Positioning Techniques and Systems,” IEEE Transactions on Systems, Man, and
Cybernetics, Part C: Applications and Reviews, vol. 37, no. 6, pp. 1067–1080,nov. 2007.
[3] P. Bahl and V. N. Padmanabhan, “RADAR: An in-building RF-based user
location and tracking system,” Proc. IEEE INFOCOM 2000, Mar. 2000, vol.2,
pp. 775–784.
[4] M. Youssef and A. K. Agrawala, “Handling samples correlation in the Horus system,” Proc. IEEE INFOCOM 2004, Mar. 2004, vol. 2, pp. 1023–1031.
[5] MIT Cricket Indoor Location System. [Online]. Available: http://
nms.lcs.mit.edu/cricket/.
[6] R.Want, A. Hopper, V. Falcao, and J. Gibbons, “The active badge location
system,” ACM Trans. Inf. Syst., pp. 91–102, Jan. 1992.
[7] N. S. Correal, S.Kyperountas,Q. Shi, and M.Welborn, “An ultra wideband relative location system,” Proc. IEEE Conf. Ultra Wideband Syst. Technol., Nov. 2003, pp. 394–397.
[8] J. Hightower, R. Want, and G. Borriello, “SpotON: An indoor 3D location
sensing technology based on RF signal strength,” Univ. Washington, Seattle,
Tech. Rep. UW CSE 2000-02-02, Feb. 2000.
[9] L.M. Ni, Y. Liu. Y.C. Lau and A.P. Patil, “LANDMARC: Indoor Location
Sensing Using Active RFID,” Proc. IEEE Int’l Conf. Pervasive Computing and
Comm. 2003, pp. 407–415, Mar. 2003.
[10] Y. Zhao, Y. Liu, and L.M. Ni, “VIRE: Active RFID-Based Localization Using
Virtual Reference Elimination, ” Proc. IEEE Int’l Conf. Parallel Processing
(ICPP), pp. 56–63, 2007
[11] A. Athalye, V. Savic, M. Bolic, and P. M. Djuric, “Novel semi-passive RFID system for indoor localization,” IEEE Sensors J., vol. 13, no. 2, pp. 528–537, Feb. 2013.
[12] S. S. Saad and Z. S. Nakad, “A standalone RFID indoor positioning system using passive tags,” IEEE Trans. Ind. Electron., vol. 58, no. 5, pp. 1961–1970, May 2011.
[13] Z. Zhang et al., “Item-level indoor localization with passive UHF RFID based on tag interaction analysis,” IEEE Trans. Ind. Electron., vol. 1,no. 4, pp. 2122–2135, Apr. 2014.
[14] Chia-Yu Yao,and Wei-Chun Hsia, “A−21.2-dBm Dual-Channel UHF Passive
CMOS RFID Tag Design,” IEEE Trans. Circuits Syst. I, Reg. Papers, vol. 61,
pp. 1269–1279, April 2014.
[15] K. Finkenzeller, RFID Handbook: Fundamentals and Applications in Contactless
Smart Cards and Identification, 3nd ed. New York: Wiley, 2010.
[16] Miodrag Boli´c, David Simplot-Ryl, Ivan Stojmenovi´c, RFID SYSTEMS: RFID SYSTEM SRESEARCH TRENDS AND CHALLENGE, 2nd ed. New York:
Wiley, 2010.
[17] Joshua D. Griffin and Gregory D. Durgin, “Complete Link Budgets for
Backscatter-Radio and RFID Systems,” IEEE Transactions on Antennas and
Propagation, vol. 51, no. 2, pp. 11–25, April 2009.
[18] Hui Liu, Darabi, H., Banerjee P., Jing Liu, “Survey of Wireless Indoor Positioning Techniques and Systems,” IEEE Transactions on Systems, Man, and
Cybernetics, Part C: Applications and Reviews, vol. 37, no. 6, pp. 1067–1080, Nov. 2007.
[19] D. M. Dobkin,The RF in RFID: passive UHF RFID in practice, Burlington,
MA: Elsevier, 2007.
[20] J. F. Dickson,“On-chip high-voltage generation in MNOS integrated circuits using an improved voltage multiplier technique,” IEEE J. Solid-State Circuits, vol. SC-11, pp. 374–378, June 1976.
[21] J. Curty, N. Joehl, C. Dehollain, and M. J. Declercq, “Remotely powered addressable UHF RFID integrated system,” IEEE J. Solid-State Circuits, vol. 40, pp. 2193–2202, Nov. 2005.
[22] U. Karthaus and M. Fischer, “Fully integrated passive UHF RFID transponder IC with 16.7 W minimum RF input power,” IEEE J. Solid-State Circuits, vol. 38, pp. 1602–1608, Oct. 2003.
[23] J.-W. Lee and B. Lee, “A long-range UHF-band passive RFID tag IC based on high-Q design approach,” IEEE Trans. Ind. Electron., vol. 56, pp. 2308–2316, July 2009.
[24] M. Baghaei-Nejad, etal:, “A remote-powered RFID tag with 10 MB/s UWB
uplink and −18:5 dBm sensitivity UHF downlink in 0.18 m CMOS,” ISSCC
Dig. Tech. Papers, Feb. 2009, pp. 198–200.
[25] S. Radiom, etal:, “Far-field on-chip antennas monolithically integrated in a wireless-powered 5.8 GHz downlink/UWB uplink RFID tag in 0.18- m standard CMOS,” IEEE J. Solid-State Circuits, vol. 45, pp. 1746–1758, Sep. 2010.
[26] G. Seigneuret, E. Bergeret, C. Moreaux, T. Deleruyelle, and P.Pannier, “Influence of multiantenna tag on the read range of a passive UHF RFID system,” IEEE Antennas Wireless Propag. Lett., vol. 10, pp. 1174–1177, Oct. 2011.
[27] Y.-S. Chen, S.-Y. Chen, and H.-J. Li, “A novel dual-antenna structure for UHF RFID tags,” IEEE Trans. Antennas Propag., vol. 59, pp. 3950–3959, Nov. 2011.
[28] C.-Y. Yao, W.-C. Hsia, and Y.-H. Ko, “A dual-channel UHF passive CMOS
RFID tag design,” Proc. 2012 Asia-Pacific Microwave Conf., pp. 1145–1147,
Dec. 2012.
[29] X. Luo, W. J. O’Brien, and C. L. Julien, “Comparative evaluation of received signal-strength index (RSSI) based indoor localization techniques for construction jobsites,” Advanced Engineering Informatics, vol.25, pp. 355–363, 2011.
[30] EPCglobal Inc., Radio-Frequency Identity Protocols Class-1 Generation 2 UHF RFID Protocol for Communications at 860 MHz-960 MHz. Version 1.2.0, Oct.
2008.
[31] YAGEO Corp., Data sheet of 433-MHz YAGEO’s chip antenna, p/ n:
CAN4311050060431K.
[32] J. Yi, W.-H. Ki, and C.-Y. Tsui, “Analysis and design strategy of UHF micropower CMOS rectifiers for micro-sensor and RFID applications,” IEEE Trans. Circuits Syst. I, Reg. Papers, vol. 54, pp. 153–166, Jan. 2007.
[33] R. Barnett, etal:, “A passive UHF RFID transponder for EPC Gen 2 with −14 dBm sensitivity in 0.13 m CMOS,” ISSCC Dig. Tech. Papers, Feb. 2007, pp.
582–583.
[34] Impinj, Inc. (2012, July). IPJ Indy R2000 Reader Chip Datasheet. Reader
Chips [Online]. Available: http://www.impinj.com/support/downloadable.documents.aspxIndy