applied wireless electronics grzegorz budzy „ lecture 5: rfid

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LLectureecture 55::RFIDRFIDWirelessWireless data transfer data transfer –– WiMAXWiMAX

Plan• RFID

– Introduction

– Tags

– Reader

– Communication

– Middleware

• WiMAX

– WiMAX standards

– WiMAX vs OSI model

– WiMAX architecture

RFID - Introduction

What is RFID?

• RFID means Radio Frequency IDentification

• RFID is An ADC (Automated Data Collection) technology that:– uses radio-frequency waves to transfer data

between a reader and a movable item to identify, categorize, track..

– Is fast and does not require physical sight or contact between reader/scanner and the tagged item.

What is RFID?

• RFID is An ADC (Automated Data Collection) technology that:– Performs the operation using low cost

components.

– Attempts to provide unique identification and backend integration that allows for wide range of applications.

• Other ADC technologies: Bar codes, OCR.

What is RFID?

Eth

ern

et

RFID

Reader

RFID Tag RF Antenna Network Workstation

Why RFID?• Tag detection not requiring human intervention

reduces employment costs and eliminates human errors from data collection,

• As no line-of-sight is required, tag placement is less constrained,

• RFID tags have a longer read range than, e. g., barcodes,

Why RFID?• Tags can have read/write memory capability, while

barcodes do not,

• An RFID tag can store large amounts of data additionally to a unique identifier,

• Unique item identification is easier to implement with RFID than with barcodes,

Why RFID?• Tags are less sensitive to adverse conditions (dust,

chemicals, physical damage etc.),

• Many tags can be read simultaneously,

• RFID tags can be combined with sensors,

• Automatic reading at several places reduces time lags and inaccuracies in an inventory

Why RFID?• Tags can locally store additional information; such

distributed data storage may increase fault tolerance of the entire system,

• Reduces inventory control and provisioning costs,

• Reduces warranty claim processing costs.

RFID – applications• Manufacturing and Processing

– Inventory and production process monitoring

– Warehouse order fulfillment

• Supply Chain Management

– Inventory tracking systems

– Logistics management

• Security

– Access control

– Counterfeiting and Theft control/prevention

• Location Tracking

– Traffic movement control and parking management

– Wildlife/Livestock monitoring and tracking

RFID Tags

Basic Tag Operation

NN

SS

TAG

Reader

Reader

TAG

BackscatterBackscatterInductive CouplingInductive Coupling

Basic Tag Operation• Near field (LF, HF): inductive coupling of tag to magnetic field

circulating around antenna (like a transformer)

• Varying magnetic flux induces current in tag. Modulate tag load to

communicate with reader

• field energy decreases proportionally to 1/R3

• Far field (UHF, microwave): backscatter.

• Modulate back scatter by changing antenna impedance

• Field energy decreases proportionally to 1/R

• Boundry between near and far field: R = wavelength/2π

• Absorption by non-conductive materials significant problem for

microwave frequencies

Tags Types

• Passive Tags

– Do not require power – Draws from Interrogator Field

– Lower storage capacities (few bits to 1 KB)

– Shorter read ranges (10 cm to 3 m)

– Usually Write-Once-Read-Many/Read-Only tags

– Cost around 25 cents to few dollars

Tags Types

• Active Tags

– Battery powered

– Higher storage capacities (512 KB)

– Longer read range (600m)

– Typically can be re-written by RF Interrogators

– Cost around 50 to 250 dollars

Electronic Product Code

Tag Architecture

ProtocolEngine

ProtocolEngine

ReceiverReceiver

MemoryMemory

Ante

nna

Ante

nna

Write Path

D

S

G

RFID Tag memory• Read-only tags

• Tag ID is assigned at the factory during manufacturing

– Can never be changed

– No additional data can be assigned to the tag

• Write once, read many (WORM) tags– Data written once, e.g., during packing or

manufacturing

– Tag is locked once data is written

– Similar to a compact disc or DVD

• Read/Write – Tag data can be changed over time

– Part or all of the data section can be locked

802.11n

18000-4EPC C0, C1, C1G2,

18000-6

18000-3.1,

15693,14443 A, B,

and C

11784/85, 14223Existing

standards

3%6%17%74%Market share

Transportation

vehicle ID (road

toll),

Access/Security,

large item

management,

supply chain

Transportation

vehicle ID,

Access/Security,

large item

management,

supply chain

Small item

management,

supply chain,

Anti-theft, library,

transportation

Smart Card,

Ticketing, animal

tagging,

Access, Laundry

Application

Electro magneticElectro magneticMagneticMagneticCoupling

10M2-7 M1M10 cmRead Range

2.45 - 5.8 GHz866 - 915MHz13.56 MHz125 - 134KHzFreq. Range

MicrowaveUHFHFLF

RFID Readers

RFID Readers• Reader functions:

– Remotely power tags

– Establish a bidirectional data link

– Inventory tags, filter results

– Communicate with networked server(s)

– Can read 100-300 tags per second

• Readers (interrogators) can be at a fixed point such as– Entrance/exit

– Point of sale

• Readers can also be mobile/hand-held

RFID Reader

915MHz

Radio

Network

Processor

Digital Signal

Processor

(DSP)

13.56MHz

Radio

Power

Supply

RFID Reader – block diagram

Transmit path Receive Path Frequency Synthesizer Digital

RFID READER

RF ModuleDAC

Host Device

ADC

Crystal

Micro-

Controller

AGC FiltersI/Q

Demod

PLL

VCO

DAC Power Control

PA

Filter Coupler

Coupler

Power

Detect

Coupler

FPGA

Regulatio

n

Baseband

&

Protocol

RFID Reader – software stack

RFID Reader API Library

Custom

Application/

Protocol

Reader

Protocol

ApplicationNetw

ork

management

File

Systems

Network

Protocols

High-Level Interfaces

Low-Level Interfaces

O/S

Hardware

Platform API Libraries

Custom

Application/

Protocol

Custom

Application/

Protocol

Network Interface

RFID Communication

RFID Communication

Tags

Reader

Power from RF field

Reader

Antenna

Reader->Tag Commands

Tag->Reader Responses

RFID Communication

Channel

RFID Communication

RFID Communication• Host manages Reader(s) and issues Commands

• Reader and tag communicate via RF signal

• Carrier signal generated by the reader

• Carrier signal sent out through the antennas

• Carrier signal hits tag(s)

• Tag receives and modifies carrier signal– “sends back” modulated signal (Passive Backscatter)

• Antennas receive the modulated signal and send them to the Reader

• Reader decodes the data

• Results returned to the host application

Passive RFID – limiting factors

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• Reader transmitter power (Gov’t. limited)

• Reader receiver sensitivity

• Reader antenna gain (Gov’t. limited)

• Tag antenna gain (Size limited)

• Power required at tag (Silicon process limited)

• Tag modulator efficiency

Passive RFID – limiting factors

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• Since P ~ 1/r2 , doubling read range requires 4X

the transmitter power.

• Larger antennas can help, but at the expense

of larger physical size

• More advanced CMOS process technology

helps by reducing P

• At large distances, reader sensitivity limitations

dominate.

RFID – Collisions

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• Reader-Reader Interference

• Reader-Tag Interference

RFID Middleware

RFID Middleware• In some applications RFID usage generates huge

amount of data that has to be porcesses

• Consider a supermarket chain implementing

RFID:

– 12 bytes EPC + Reader ID + Time = 18 bytes per tag

– Average number of tags in a neighborhood store =

700,000

– Data generated per second = 12.6 GB

– Data generated per day = 544 TB

– Assuming 50 stores in the chain, data generated per

day = 2720 TB

RFID Middleware

RFID Example

MFRC522- RFID Contactless Reader IC

MFRC522- RFID Contactless Reader IC• Features:

– reader/writer IC for contactless communication at 13.56

MHz

– Typical operating distance in Read/Write mode up to 50

mm depending on the antenna size and tuning

– Supports ISO/IEC 14443 A higher transfer speed

communication up to 848 kBd

– Supported host interfaces

• SPI up to 10 Mbit/s

• I2C-bus interface up to 400 kBd in Fast mode, up to 3400 kBd in

High-speed mode

• RS232 Serial UART up to 1228.8 kBd, with voltage levels dependant

on pin voltage supply

MFRC522- RFID Contactless Reader IC

What is WiMAX?

• WiMAX is a short for Worldwide Interoperability for Microwave Access

• WiMAX telecommunication protocols areimplmentation of IEEE 802.16 recommendations

• The name "WiMAX" was created by the WiMAX Forum, formed in June 2001 to promote conformity and interoperability of the standard

What is WiMAX?

• WiMAX is a wide area alternative to IEEE 802.11/WiFi

• WiMAX a method for breaking wire basedcommunication monopolies

• WiMAX a method for providing backhaul to IEEE 802.11/WiFi access points

• WiMAX is, in some sort, a universal solution for broadband wireless access

What is WiMAX?

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WiMAX History

• In the mid-1990’s, various groups began to promote “last-mile” fixed wireless access solutions.

• Multiple goals:– Provide the capacity and reliability of wire based

communication but with the flexibility and ease of deployment of wireless

– Provide a versatile system for corporate orinstitutional backhaul/distribution networks

– Break the monopolies of incumbent carriers

WiMAX History

• Interest soon focused in two approaches.– LMDS – Local Multipoint Distrubiution Service

• operates in 26-29 GHz spectrum under LoSconditions

• uses conventional QAM modulation with ATMderived upper layers to provide high speed service

• Distance is typically limited to about 2.4 km

• Links up to 8km in point-to-point configurations

WiMAX History

• Interest soon focused in two approaches.– MMDS – Multichannel Multipoint Distribiution

Service• Known also under the name of Broadband Radio

Service (BRS)

• an alternative method of cable television programming reception

• uses microwave frequencies at 2.1 GHz and from 2.5 GHz to 2.7 GHz, usually under LoS conditions

• may use any of various PHY, MAC, and NET layers

• provided significantly greater range than LMDS

WiMAX History

• High costs, lack of standards and fear of vendor lock-in drove off potential LMDS customers.

• In 1999, IEEE 802.16 was formed to address these issues by developing open standards for LMDS.

• In 2001, the IEEE 802.16 standard for BWA (Brodband Wireless Access) systemsoperating in the 10-66 GHz range was released

WiMAX History

• 802.16-2001 Fixed Broadband Wireless Access (10–66 GHz)

• 802.16a-2003 Physical layer and MAC definitions for 2–11 GHz

• P802.16.2a Coexistence with 2–11 GHz and 23.5–43.5 GHz

• 802.16e-2005 Mobile Broadband Wireless Access System

• 802.16-2009 Air Interface for Fixed and Mobile Broadband Wireless Access System

• 802.16m-2011 Advanced Air Interface with data rates of 100 Mbit/s mobile and 1 Gbit/s fixed.

Wi-Fi – Standards

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WiMAX – applications

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WiMAX Services

• Digital audio/video multicast

• Digital telephony

• ATM

• Internet protocol

• Bridged LAN

• Back-haul

• Frame relay

WiMAX – Key features

• Major goal of IEEE 802.16 (2-11 GHz): provide a “universal” solution for broadband wireless access– point-to-multipoint, LoS or NLoS

– ranges of “several” km; urban, suburban, rural

• Operating Frequency: 2 – 11 GHz

• Allocations: Licenced and Unlicenced

• Channel Bandwidth: 1.25 – 20 MHz


• Modulation: Single carrier, 256 OFDM, 2048 OFDMA, BPSK, QPSK, 16-QAM, 64-QAM, 256-QAM

• Antenna system support: Diversity, MIMO, SDMA

• Duplexing: FDD, H-FDD, TDD

• Data Rates: From T1 (1.5 MB/s) to over 70 Mb/s


• The IEEE 802.16 MAC layer supports– OFDM and OFDMA

– ARQ (Automatic Repeat Request)

– Dynamic Frequency Selection

– Mesh Networking

– Advanced Antenna Systems

– Differentiated Quality of Service

– Enhanced Security

WiMAX vs OSI model

WiMAX – MAC layer• Connection oriented

– Connection ID (CID), Service Flows

• Channel access: decided by BS– UL-MAP

• Defines uplink channel access

• Defines uplink data burst profiles

– DL-MAP• Defines downlink data burst profiles

– UL-MAP and DL-MAP are both transmitted in the beginning of each downlink subframe

WiMAX – physical layer• Allows use of directional antennas

• Allows use of two different duplexingschemes:– Frequency Division Duplexing (FDD)

– Time Division Duplexing (TDD)

• Support for both full and half duplex stations

• Adaptive Data Burst profiles– Transmission parameters (e.g. Modulation, FEC)

can be modified on a frame-by-frame basis for each SS

– Profiles are identified by ”Interval Usage Code”

WiMAX – physical layer implmentation

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WiMAX Frame Format

• Header - protocol control information

– Downlink header – used by the base station

– Uplink header – used by the subscriber to convey

bandwidth management needs to base station

– Bandwidth request header – used by subscriber to

request additional bandwidth

• Payload – either higher-level data or a MAC

control message

• CRC – error-detecting code

WiMAX – physical layer - Downlink• Continuous downstream mode

– For continuous transmission (audio/video)

– Simple TDM scheme is used for channel access

– Frequency division duplex (FDD)

• Burst downstream mode– For bursty transmission (IP-based traffic)

– DAMA-TDMA scheme for channel access

– FDD with adaptive modulation, frequency shift division duplexing (FSDD), time division duplexing (TDD)

WiMAX – TDD Downlink subframe

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WiMAX – physical layer - Uplink• Stations transmit in in their assigned

allocation specified in an initial map

• Uplink sub-frame may also contain contention-based allocations for initial system access

• Uses a DAMA-TDMA technique

• Error correction uses Reed-Solomon codes

• Modulation scheme based on QPSK, 16-QAM or 64-QAM

WiMAX – Uplink subframe

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WiMAX frequency channels

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WiMAX Peak Raw Data Rates• Assumptions:

– 10MHz bandwidth

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WiMAX architecture

WiMAX topology - PMP• PMP – point-to-multipoint: the central point

of the network is the Base Station (BS)

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WiMAX topology - mesh• In mesh topology there is no central point of

the network. The traffic may go through BS or

directly between single stations (SS).

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WiMAX topologies

• A major advantage of the Mesh mode is that the

reach of a BS can be much greater, depending on

the number of hops, until the most distant SS.

• On the other hand, using the Mesh mode brings

up the now thoroughly studied research topic of

ad hoc (no fixed infrastructure) networks routing

(more difficult).

WiMAX topologies

• When authorised to a Mesh network, a

candidate SS node receives a 16-bit Node ID

(IDentifier) upon a request to an SS identified as

the Mesh BS.

• The Node ID is the basis of node identification.

• The Node ID is transferred in the Mesh

subheader of a generic MAC frame in both

unicast and broadcast messages.

WiMAX application example

WiMAX transceiver AT86RF535B

• Single-chip 3.5GHz WiMAX Transceiver

• Low-IF/Zero-IF Transceiver Architecture; Requires No

External Filters

• Support Channel Bandwidths of 3.5, 5.0, 7.0,

8.75MHz, and 10MHz

• Modulation up to 64QAM

• Ultra-fast Fractional-N Synthesizer

• Sensitivity < -74 dBm at 64-QAM, 7MHz BW

• Low Supply Voltage: 3.0 V


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• Functional description:

– based on the IEEE 802.16-2004 standard

– provides transmit, receive, and frequency synthesis

functions using the OFDM modulation schemes

– consists of a frequency-agile RF transceiver intended for use

in 3.5-GHz licensed bands at data rates up to 26Mbps

– addresses the requirements of base station (BS) as well as

subscriber stations (SS) equipment

– Configuration and control registers and a bi-directional data

communication over SPI interface


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Thank you for your attention

References[1] http://www.naclin.org/RFID-SECURITY-Bibhuti.ppt#259,4,Brief History

[2] “Introduction to RFID” CAENRFID an IIT Corporation

[3] www.rfidprivacy.org

[4] Lundmark T., „ WiMAX - a sneak preview”, TietoEnator

[5] „WiMAX, making ubiquitous high-speed data services a reality”, WhitePaper, Alcatel

[6] www.altera.com

[7] Sridhar Iyer, „ WiMAX: IEEE 802.16 - Wireless MANs”, http://www.it.iitb.ac.in/~sri

[8] AT86RF535B documentation, www.atmel.com

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