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