1. Radio Frequency Identification and Near Field Communication
RFID & NFC
Radio Frequency Identification and Near Field Communication
11/12/2018
Chao GAO, VAMK

2. RFID tag A system to identify a person/product/thing, etc.
Each "thing" is implanted with a "tag", in different forms.
Paper tag, EPC tag, Inlay tag, Glue tag, Key tag, Glass tube tag, Disc tag, Pocket tag.
Several classes of tag:
Class 0: passive read-only, non-programmable
Class 1: passive read-only, programmable
Class 2: passive read-write, 56kB memory
Class 3: semi-passive read-write, powered by battery
Class 4: active
Class 5: active, can communicate with other class 5 tags.
microchip
antenna
11/12/2018
Chao GAO, VAMK

3. Tag Information: EPC
Most common (and standard) information in a tag is Electronic Product Code (EPC).
Most versions of EPC is 64- or 96-bit long, divided into 4 parts:
Header: 8 bits, identifies the length, type, version of EPC
Domain manager: 28 bits, identifies the manufacturer
Object class: 24 bits, identifies a product's stock keeping unit (SKU), e.g., different size/color of a T-shirt.
Serial number: 36 bits, identifies each instance of product.
Header
8 bits
Domain manager
28 bits
Object class
24 bits
Serial number
36 bits
11/12/2018
Chao GAO, VAMK

4. RFID Frequencies ISO-18000 specifies operating frequencies of RFID:
ISO-18000v2: Low-frequency 135kHz, typically used for animal tracking because it is affected much by water or metal.
ISO-18000v3: High-frequency 13.56MHz, typically used in short range such as book tracking in library.
ISO-18000v4: Microwave 2.45GHz
ISO-18000v6: Ultra-high frequency MHz, offers longer range of reading
ISO-18000v7: Ultra-high frequency 433MHz
Higher frequencies require smaller size antennas.
11/12/2018
Chao GAO, VAMK

5. How it works (Passive)
A passive RFID tag has no power. It couples energy emitted from a RFID reader.
Inductive coupling or magnetic coupling requires the tag to be very close to the reader (1cm) so that enough energy can be (inductively) coupled.
Backscatter coupling uses a backscatter (reflective) antenna, the tag is designed so that data is superimposed into (usually ASK modulation) the carrier wave and reflected back to the reader. Because of its mechanism, the range can be up to 100 meters.
RFID reader
RFID
Reader
Antenna
Circuits
RFID
tag
Magnetic field
11/12/2018
Chao GAO, VAMK

6. How it works (Collision Avoidance)
When there are multiple RFID-ed products scanned by the same reader, a Slotted Teminating Adaptive Collection (STAC) protocol is used in HF tags.
The number of slots cannot be very big (increased delay).
More sophisticated anti-collision protocols can be seen in [Klair, 2010].
Reading cycle
RFID
Reader F
Slot1
Slot2
Slot3
Slot4
Slot5
Slot6
Slot7
Slot8
SlotX
SlotN F
Each tag generates a random number between 1 and N
11/12/2018
Chao GAO, VAMK

7. Near Field Communications
NFC
Near Field Communications
11/12/2018
Chao GAO, VAMK

8. What is NFC?
Based on ISO (which is a RFID standard), and ISO (known as NFCIP-2).
Most smartphones, credit cards/bank cards, discount coupons/gift cards, bus cards have chosen NFC.
It uses loop antennas (near field) between two NFC devices to communicate with each other.
The memory of NFC tags is usually much bigger than RFID tags, able to store URLs, business cards, pictures, brochures in PDF format, etc.
Working frequency is 13.56MHz (same as RFID HF). Data rate kbps.
Modulation is ASK and PSK.
11/12/2018
Chao GAO, VAMK

9. Operating Modes of NFC Devices
Reader/Writer Mode
Peer to Peer Mode
Card Emulation Mode

10. NDEP/NDEF
NFC Data Exchange Protocol/Format
11/12/2018
Chao GAO, VAMK

11. NFC Programming in Andriod
Write a tag with URL
import android.nfc.*;
import android.nfc.tech.MifareClassic;
import android.nfc.tech.Ndef;
import android.nfc.tech.NdefFormatable;
import android.nfc.tech.NfcA;
protected void onNewIntent(Intent intent) {
super.onNewIntent(intent);
if (mNfcAdapter.ACTION_TECH_DISCOVERED.equals(intent.getAction())) {
Tag tag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
NdefMessage ndefMessage = getNoteAsNdef();
if (ndefMessage != null) {
writeTag(getNoteAsNdef(), tag);
} else {
toast("Expection. Try Again"); }
private NdefMessage getNoteAsNdef() {
//… prepare necessary values for URL
String url = "
NdefRecord rtdRecord = NdefRecord.createUri(url);
return new NdefMessage(new NdefRecord[] { rtdRecord }); }
11/12/2018
Chao GAO, VAMK

12. boolean writeTag(NdefMessage message, Tag tag) {
int size = message.toByteArray().length;
try {
Ndef ndef = Ndef.get(tag);
if (ndef != null) {
ndef.connect();
if (!ndef.isWritable()) {
toast("Error:Tag can not be write"); return false; }
if (ndef.getMaxSize() < size) {
toast("Error:Data payload is overflow. "); return false;
ndef.writeNdefMessage(message);
toast("write successful!");
alertDialog.dismiss();
ndef.close();
return true;
} else {
//… return false;
catch (Exception e) {
toast("Error: Write data failure");
return false;
11/12/2018
Chao GAO, VAMK