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1.6 RFID Inventory SystemCody Lovejoy Ramsey Doany Kyle Jones
Ingram School of EngineeringTexas State University
PROBLEM STATEMENT
• The International Space Station (ISS)
• Power Consumption
• Current RFID Inventory System• Inefficient• Wasteful
WHAT IS RFID?
• Radio Frequency Identification
• Credit Cards
• Key Cards
• Inventory
• Passive• RLC Circuit• Induction• Frequency• Antenna
• Microchip• Data (128 bit)• Random Number Generator• Handle• Response Delay Time
RFID SYSTEMTag Reader
• Antenna• Transceiver• Computer/Software• Modulation/Coding• Demodulation/Decoding
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
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
THE BASICS• Decrease bit period Increase transmission speed
• Increase transmission speed Increase bandwidth occupied by bit
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
OPERATION1. 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
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
• 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
SUPERIORITY OF CDMA-BASED SYSTEMTDM-Based System CDMA-Based System
DESIGN POSSIBILITIES1. Physical implementation of CDMA/DSSS
• Disable RNG (or set all RNG to select same value)
• EPC data encoded according to spreading code
2. Standard Protocol/Time Shift
• Use current system to read 5 tags
• Record electrical response
• Mathematically time shift signals
• Demodulate/decode signal
3. Simulation of entire process
TEST PLAN• Trace and display single “beckoning” signal
• Trace and display summation of tag transmission (at receiver)
• Display demodulated and decoded data on PC
CONSTRAINTS• Manufacturability
• Economies of scale
BUDGET• $600
• All RFID hardware and testing equipment provided by Texas State University
• No expected additional expenditures
WORK BREAKDOWN STRUCTURE
Hardware
Alien Hardware
RFID Tag
RNG
Software
Tag
EPC
ID
Spreading Codes
PC
Demodulation/decoding
Data Storage
TIMELINE
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec2015
Read/WriteTags(CurrentSystem)
SelectMUXTechnique
CharacterizeCurrentOutput
DesignTag Mods
ModTags
BeginSoftwareDesign
ImplementSoftware
1 TagFunctioning
3 TagsFunctioning
5 TagSystemComplete
BeginTesting
AT OUR BOOTH• Alien ALR 9900+ RFID Development System
• Images of acquired transmission signals
• Mathematical proof of claims