無線射頻被動式標籤之容許碰撞識別法

隨著無線射頻識別技術的進步，逐漸改變了人們的生活型態。由於無線射頻技術的讀取速度以及便利性，可以有效地提高工作效率，縮短管理時間。目前，更有逐漸取代條碼的趨勢，對大量的人力、貨品進行管理。因此，多標籤的識別技術顯得特別重要。為了更有效提高無線射頻識別技術在多標籤讀取的運作速度，有許多問題必須解決。本篇論文將會針對當中影響識別速度最嚴重的「標籤碰撞」問題提出可行的解決方法。目前針對碰撞問題的研究，大部分都是設法去「避免」碰撞。不同於目前大部分的反碰撞演算法，我們將嘗試讀取出碰撞的訊號。利用領航訊號建立碰撞位元的樣本波形，並加以比對碰撞位元的波形，將原本完全無法識別的碰撞訊號，改良為在兩個標籤碰撞下，仍有35%的機率將兩個標籤都讀取出來，而有60%的機率能讀取出一個標籤。除此之外，也將針對目前的反碰撞搜尋法提出改良的演算法，其讀取多個被動式標籤的時間最多可以縮短50%。而在時隙ALOHA系統中，本篇論文也對被動式標籤個數的估測提出更準確的方法。在準確的個數估測之下，可以決定最適合的訊框長度，並能提升20%以上的系統效能。

關鍵字

無線射頻技術；封包正確率；反碰撞搜尋法；二元樹演算法；二元搜尋法；時隙ALOHA演算法；標籤個數估測；卡爾曼濾波器

並列摘要

Development of Radio Frequency Identification (RFID) is changing our life style. Better efficiency and less time can be achieved due to the fast reading speed and convenience of RFID. Recently, barcode is substituted by RFID in the applications of the management of large amount of products and people. Therefore, the identification technique of multiple tags becomes more significant. In order to enhance the identification speed of multiple tags, there are many problems to be solved. In this thesis, the solution of collision, which impacts identification speed most, is proposed. Instead of avoiding collisions which most researches focus on, the identification of collision signals is another feasible method. The samples of collision signals are used to compare with later collision signals for identification. Hence, the probabilities of one-tag and two-tag successful identification are 60% and 35% respectively in case of two tags collision. Besides, improved anti-collision algorithms are presented. Up to 50% time reduction of multiple tags identification can be achieved among these methods. In Framed Slotted ALOHA system, better tag estimation methods are proposed. Most suitable frame size can be acquired by acute tag estimation and further increases system efficiency by 20%.

並列關鍵字

RFID ； packet correct rate（PCR）； anti-collision ； binary tree algorithm ； binary search algorithm ； framed slotted ALOHA ； tag estimation ； Kalman filter

參考文獻

[8] “Draft protocol specification for a 900 MHz Class 0 Radio Frequency Identification Tag”. Auto-ID Center, Feb. 2003.

[9] Nan Zhang, Branimir Vojcic, “Binary Search Algorithms with Interference Cancellation for RFID Systems,” Military Communications Conference. 2005. MILCOM 2005. IEEE, 2005. vol. 2, p.p. 950 - 955, 2005.

[10] Jihoon Myung, Wonjun Lee, ”Adaptive Splitting Protocols for RFID Tag Collision Arbitration,” Mobile Networks and Applications, vol. 11, p.p. 711-722, May 2006.

[12] Jae-Ryong Cha, Jae-Hyun Kim, “Dynamic Framed Slotted ALOHA Algorithm using Fast Tag Estimation Method for RFID System,” IEEE CCNC 2006 proceedings.

[14] H. Vogt, “Efficient object identification with passive RFID tags,” Lecture Notes in Computer Science, vol. 2414, Springer Berlin/Heidelberg, Aug. 2002.

國際替代計量

無線射頻被動式標籤之容許碰撞識別法

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