1.6 RFID Inventory System

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1.6 RFID Inventory System
Cody Lovejoy Ramsey Doany Kyle Jones
Ingram School of Engineering Texas State
University
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Problem Statement

• The International Space Station (ISS)
• Power Consumption
• Current RFID Inventory System
• Inefficient
• Wasteful

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What is RFID?

• Radio Frequency Identification
• Credit Cards
• Key Cards
• Inventory

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RFID System
Tag
Reader

• Passive
• RLC Circuit
• Induction
• Frequency
• Antenna
• Microchip
• Data (128 bit)
• Random Number Generator
• Handle
• Response Delay Time

• Antenna
• Transceiver
• Computer/Software
• Modulation
• /Coding
• Demodulation
• /Decoding

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Current Operation (TDM)
Tag Power-Up/Search Query
Load 2Q-1 Bit RNG
Decrement/Search Query
Handle Number
ACK
Tag Data
ACK/Tag Power-Down
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Proposal

• TDM CDMA/DSSS
• Conform to Class I Gen. II Specs
• 75 reduction in power consumption
• Read 5 tags simultaneously
• Alien ALR 9900 RFID
• Development System

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The Basics

• Decrease bit period Increase transmission speed
• Increase transmission speed Increase bandwidth
  occupied by bit

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CDMA/DSSS

• Code Division Multiple Access (CDMA)
• Multiplexing
• Multiple users occupy channel simultaneously
• Orthogonal spreading codes
• Direct Sequence Spread Spectrum
• Spreading signal bandwidth
• Increase transmission speed
• Bit redundancy

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operation

1. Transmitter receives user data
2. Data clocked into XOR circuit
3. Spreading code n times longer than user data
   sequence clocked into same circuit n times as
   fast
4. User data signal effectively spread over
   bandwidth n times as wide as original data
5. Receiver XOR signal with same spreading code to
   de-spread (decode) signal

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CDMA-based rfid system
Tag Power-Up/Query
Tag Data

• Single beckoning signal
• All tags respond simultaneously (128 bit EPC
  data)
• Reader receives summation of all tag
  transmissions
• Reader demodulates/decodes signal

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Superiority of CDMA-based system

• TDM-Based System

• CDMA-Based System

• 1 transmission (any number of tags)
• 98.5 less power consumption

• Brute force method
• At least 69 transmissions (5 tags, assuming no
  collisions)
• Reader constantly scanning

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Design Possibilities

• Physical implementation of CDMA/DSSS
• Disable RNG (or set all RNG to select same value)
• EPC data encoded according to spreading code
• Standard Protocol/Time Shift
• Use current system to read 5 tags
• Record electrical response
• Mathematically time shift signals
• Demodulate/decode signal
• Simulation of entire process

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Test Plan

• Trace and display single beckoning signal
• Trace and display summation of tag transmission
  (at receiver)
• Display demodulated and decoded data on PC

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Constraints

• Manufacturability
• Economies of scale

Budget

• 600
• All RFID hardware and testing equipment provided
  by Texas State University
• No expected additional expenditures

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Work Breakdown Structure
Software
Tag
Hardware
EPC
Alien Hardware
ID
RFID Tag
Spreading Codes
RNG
PC
Demodulation/decoding
Data Storage
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Timeline
2015
Jan Feb Mar Apr May Jun Jul Aug Sep Oct
Nov Dec
3 Tags Functioning
Begin Software Design
Design Tag Mods
Select MUX Technique
Read /Write Tags (Current System)
1 Tag Functioning
5 Tag System Complete
Mod Tags
Begin Testing
Implement Software
Characterize Current Output
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At our booth

• Alien ALR 9900 RFID Development System
• Images of acquired transmission signals
• Mathematical proof of claims