近年來，被動式射頻辨識系統應用越來越受到重視。在被動式射頻辨識系統中，標籤需依靠讀取機所傳送之連續載波而獲得能量，因此讀取距離受到限制。故有許多延長讀取距離之研究被提出。
　　本篇論文中，我們使用多載波系統提供能量給被動式標籤。在讀取機範圍內利用類似於細胞式基地台的配置方法佈置連續波發射器，以提供額外能量給標籤。連續波發射器所提供之能量，必須同時考慮標籤最小調變深度和最小工作能量限制，因此連續波發射器傳送之能量必須謹慎選擇。
　　本篇論文中，我們推導出連續波發射器傳輸功率之理論分析。假設標籤均勻分佈於讀取機可讀範圍內，可依理論結果分析導出最佳連續波發射功率，以得到最大可讀取範圍。
　　模擬結果顯示，將連續波發射器所傳送之能量最佳化，可獲得較好之讀取範圍延伸。此外，使用修正化讀取器指令，可減少標籤受到調變深限制影響，因此更進一步延長讀取範圍。

In recent years, the applications of passive RFID systems have gained more attentions. Because a tag must obtain its operating power from a continuous wave transmitted from a reader In a passive RFID system, the readable range is hence limited. Consequently many researches on readable range extension have been proposed.
In this thesis, we use a multi-carrier method to supply the operating power of a passive tag. In an interrogation region, continuous wave emitters, which provide additional operating power to passive tags, are deployed following the similar manner of base station deployment in a cellular phone system. Because the transmission powers of continuous wave emitters must jointly consider the tag minimum modulation depth constraint and the tag minimum operating power requirement, the transmission powers of continuous wave emitters must be carefully chosen.
In this thesis, an analytical analysis of continuous wave emitter transmission powers is derived. Assuming all tags are uniformly distributed in an interrogation region, the optimum continuous wave emitter transmission power that leads to the largest reader readable range can be obtained according to the analysis.
Simulation results show that the optimization of continuous wave emitter transmission powers can achieve better read range extension. In addition, using modified waveform command can loosen the tag modulation depth constraint and hence further extend the reader coverage.

[1] J. Landt, “The history of RFID”, IEEE Potentials, 2005.
[2] H. C. Liu, Yung-Ting Chen and Wen-Shin Tzeng, “A Multi-Carrier UHF Passive RFID System,” in Proc. 2007 International Symposium on Applications and the Internet Workshops – Workshop on Networked RFID, Hiroshima, Jan. 15-19, 2007.
[3] H. C. Liu, Yi-Fan Chen and Yung-Ting Chen, “A Frequency Diverse Gen2 RFID System with Isolated Continuous Wave Emitters, ” Journal of Networks, vol. 2, no. 5, Sep. 2007.
[4] 陳奕帆，“多載波被動式射頻辨識系統研究”，國立台灣科技大學，電機工程研究所碩士論文，民國九十六年七月.
[5] L. Liu, Z. Xie, J. Xi and S. Lai, “An improved anti-collision algorithm in RFID system, ” Mobile Technology, Applications and Systems, 2005 2nd International Conference on, pp. 15-17 Nov. 2005.
[6] EPCTM Radio-Frequency Identity Protocols Class-1 Generation-2 UHF RFID Protocol for Communications at 860MHz-960MHz for Communications Version 1.09, Electronic Product Code™ (EPC) Standard, 2005.
[7] T. S. Rappaport, Wireless Communications: Principles and Practice, in Prentice Hall PTR, 2th ed, 2002.
[8] L. W. Mayer, M. Wrulich and S. Caban, “MEASUREMENTS AND CHANNEL MODELING FOR SHORT RANGE INDOOR UHF APPLICATION,” in Proc. The European Conference on Antennas and Propagation, Nice, France, Nov. 2006
[9] F. A. Alves, M. R. M. L. Albuquerque, S. G. Silva, and A. G. d’Assunção, “USING EFFICIENT RAY-TRACING TECHNIQUES TO PREDICT PROPAGATION LOSSES IN INDOOR ENVIRONMENTS,” MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Vol. 49, No. 4, Apr 2007.
[10] D. Kim, M. A. Ingram and W. W. Smith, Jr., “Measurements of small-scale fading and path loss for long range RF tags,” Antennas and Propagation, IEEE Transactions on , vol.. 51, no.8, pp. 1740-1749, Aug. 2003
[11] K. S. Leong, M. L. Ng and P. H. Cole, “Operational considerations in simulation and deployment of RFID systems,” 17th International Zurich Symposium on Electromagnetic Compatibility, Singapore, 2006
[12] K. S. Leong, M. L. Ng and P. H. Cole, “The reader collision problem in RFID systems,” Microwave, Antenna, Propagation and EMC Technologies for Wireless Communications, 2005. MAPE 2005. IEEE International Symposium on , vol.1, pp. 658-661, 8-12 Aug. 2005
[13] W. Su, N. Alchazidis and T. T. Ha, “DATA INTEGRITY IN RFID SYSTEM,” IEEE Military Communications Conference, pp. 1-7, Oct. 2007
[14] P. V. Nikitin, K. V. S. Rao, “Performance limitations of passive UHF RFID systems, ” Antennas and Propagation Society International Symposium 2006, IEEE , pp. 1011-1014, 9-14 July 2006
[15] D. M. Dobkin, “The RF in RFID: Passive UHR RFID in Practice,” in Newnes, Pap/Cdr edition, 2007.
[16] V. H. MacDonald, “The Cellular Concept,” The Bell Systems Technical Journal, vol.58, No.1, pp.15-43, Jan. 2006.