utilizing physical layer information to improve rfid tag

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Figure 3.1. Slot count (Q) selection algorithm [1]. it needs time to converge to the optimal value. This convergence time reduces the reading efficiency. Figure 3.2. Inventory sequence [1]. Figure 3.2 illustrates the sequence of commands between the RFID reader and the tags during a portion of the inventory process. The upper part of the figure shows the transmissions sent by the reader and the shaded boxes represent the tag transmissions. The reader begins the data exchange by starting an Inventory round for tag inventory and subsequent access. It then sends a Query command which contains the slot-count parameter Q. Upon receipt of this parameter, all the tags pick a slot between 0 and 2 Q -1. Tags that pick a zero shall transition to the reply state and 10
eply immediately. Tags that pick a nonzero value shall transition to the arbitrate state and await a QueryAdjust or a QueryRep command. Assuming that a single Tag replies, the query-response algorithm proceeds as follows: 1. The Tag backscatters an RN16 as it enters reply. 2. The Interrogator acknowledges the Tag with an ACK containing this same RN16. 3. The acknowledged Tag transitions to the acknowledged state, backscattering its PC, EPC, and CRC-16 [1]. In the ISO 18000-6C protocol, readers communicate with tags using DSB-ASK or PR-ASK with Pulse Interval Encoding(PIE). The tag to reader communication uses ASK modulation and FM0(bi-phase space) or Miller encoding for the data. Figure 3.3 shows the waveforms for FM0 encoding. FM0 inverts the baseband phase at every symbol boundary; a data-0 has an additional mid-symbol phase inversion. The duty cycle of a 00 or 11 sequence, measured at the modulator output, is a minimum of 45% and a maximum of 55%, with a nominal value of 50%. FM0 encoding has memory; consequently, the choice of FM0 sequences in Fig. 3.3 depends on prior transmissions. FM0 signaling always ends with a dummy data-1 bit at the end of a transmission. [1] Figure 3.3. Tag to reader data encoding [1]. 11
Page 1 and 2: UTILIZING PHYSICAL LAYER INFORMATIO
Page 3 and 4: ACKNOWLEDGEMENTS My first encounter
Page 5 and 6: This thesis proposes a method of us
Page 7 and 8: 5.3 Signal separation . . . . . . .
Page 9 and 10: 6.7 Strong and weak tag collision w
Page 11 and 12: CHAPTER 1 INTRODUCTION Radio-Freque
Page 13 and 14: and signal absorption or reflection
Page 15 and 16: 2.1 RFID Reader CHAPTER 2 PASSIVE U
Page 17 and 18: Figure 2.2. Alien Squiggle Tag. Fig
Page 19: CHAPTER 3 ISO 18000-6C PROTOCOL The
Page 23 and 24: identification times even if the nu
Page 25 and 26: difficult problem as field nulls ar
Page 27 and 28: Figure 5.1. Passive tag structure.
Page 29 and 30: Figure 5.4. Software defined radio.
Page 31 and 32: Figure 5.7. I-Q plot. Figure 5.8. 2
Page 33 and 34: 6.1 Tag estimation from collision C
Page 35 and 36: Figure 6.3. 4 tag collision. tags i
Page 37 and 38: 2. Anti-collision with enhanced tag
Page 39 and 40: Table 6.4. Results for enhanced ant
Page 41 and 42: Figure 6.8. Strong and weak tag col
Page 43 and 44: Figure 6.10. Random number distribu
Page 45 and 46: Figure 6.13. Squiggle tag. Figure 6
Page 47 and 48: Figure 6.17. Gaussian PDFs used for
Page 49 and 50: CHAPTER 7 USRP SYSTEM A software-de
Page 51 and 52: 7.2 Software GNU Radio is a free so
Page 53 and 54: CHAPTER 8 CONCLUSIONS AND FUTURE WO
Page 55 and 56: probabilty distribution. Thus there
Page 57 and 58: tions. This section contains the th
Page 59 and 60: A.1.2 Algortihm A (Reference Algori
Page 61 and 62: end end 51
Page 63 and 64: A.2.2 Inventory Round Simulation %R
Page 65 and 66: A.2.3 Predicting Number of Tags %Ru
Page 67 and 68: REFERENCES [1] EPCglobal, “Uhf cl
Page 69 and 70: [21] K. Finkenzeller, RFID Handbook

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