utilizing physical layer information to improve rfid tag

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RX: 800MHz - 1000MHz Figure 7.2. USRP and GNU Radio block diagram. TX: 800MHz - 1000MHz @ 200+mW The board features an ISM band filter that suppresses the RF signal outside the 902-928 MHz band and attenuates it within such band by one dB or two. GNU Radio implements the baseband processing in software but the high speed FPGA on the USRP can be used to speed up time critical processing where the USB latency creates a problem. 42
CHAPTER 8 CONCLUSIONS AND FUTURE WORK In this chapter we summarize the results of the research performed. This research focusses on improving the identification rate of present RFID systems. Physical layer collision signals were used for the same and changes in present algorithms are suggested. 8.1 Conclusions Section 6.1 described the results of detecting the number of tags invloved in a collision using I-Q plot. Experimental results point out that in the 3 tag case, 71% accuracy was possible while for the 4 tag case 73% accuracy was possible . Section 6.2 presented a simulation to find the theoretical performance increase using three different algorithms. The results are presented in table 8.1. Collision re- covery by extracting the individual RN16s of the two tags involved in a collision can be used to convert a collided slot to a read slot. We do not know the expected RN16 values of the tags since they are randomly generated for each session. Our algorithm is used to recover the RN16s from the colliding signals. The only way to detect if the RN16 was correct is to send an ACK to the tags with the decoded RN16 and check if the tag responds. The EPC Class 1 Gen. 2 protocol allows only single ACK command to be sent. Even if we correctly decode both RN16s, we can acknowledge only one of the tags as the other tag will also receive this ACK and discard it as incorrect. This could be solved by adding a STACK command to the protocol which instructs tags involved in a collision to wait till the ACK command formed using their RN16 is 43
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 and 20: CHAPTER 3 ISO 18000-6C PROTOCOL The
Page 21 and 22: eply immediately. Tags that pick a
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: 7.2 Software GNU Radio is a free so
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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