NFC architecture and standards involved -C&T RF Antennas Inc

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NFC architecture and standards involved
The NFC technology evolved from contactless radio frequency identification (RFID). The RFID
transmission range can reach several meters or even tens of meters. It can only read and
determine information, and NFC technology emphasizes information exchange. Near field,
communication is operated at a frequency of 13.56 MHz within a distance of 20 cm, and its
transmission speed is 106 Kbit/s, 212 Kbit/s, or 424 Kbit/s.
The Near Field Communication Forum defines three operating modes (PDF):
Point-to-point mode (P2P mode): Supports communication between two near-field
communication devices, enabling information exchange and file sharing.
Reader/writer mode: It enables the near-field smart device to read relevant information from
poster or exhibition information electronic tags.
Card emulation: Near field communication devices can be like smart cards, allowing users to pay
for retail shopping and transportation expenses.
NFC phones have built-in NFC chips, which makeup part of the RFID module and can be used as
RFID passive tags to cover expenses. They can also be used as RFID readers for data exchange and
acquisition.
NFC card emulation, reader/writer, and point-to-point three modes are divided from the
application mode. The card emulation mode is also often referred to as the read mode. The
mobile terminal can be modeled as an ordinary contactless card that can be read by the POS. This
mode usually inherits widely used applications such as bank cards and access control cards. Bus
cards, etc., use NFC mobile phones as carriers and take advantage of the advantages of mobile
phones in the network, multimedia, and human-computer interaction. The application scenarios
are also similar to the existing methods; the reader/writer mode is often called the main reading
mode, and the mobile terminal can read Take the content of a contactless card or a non-contact
tag, this mode may inherit existing applications, such as the NFC phone as a POS machine to read
the existing bank card, bus card, but also can be NFC Newly defined application scenarios, such as
the use of NFC phones to read NFC-defined targets
The standard data in the signing implements functions such as electronic business cards,
electronic posters, and WIFI connections; the peer-to-peer mode means that two mobile
terminals transmit data directly by touch in a short distance. This is a new mode defined by NFC,
and Bluetooth, WIFI has two characteristics: short distance and simple configuration.
Theoretically, it can realize the interaction of any data between two mobile phones through
simple touches, such as synchronization schedule, location sharing, and business card exchange.
NFC principle

C&T RF Antennas Inc
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NFC architecture and standards involved
Written By Calio Huang
The NFC function of the mobile terminal consists of NFC Controller, NFC protocol stack, SE, SE
access API, SE access control, and AP access SE chip. Its main functions are as follows:
1. NFC Controller: NFC chip, which implements analog and digital protocol processing defined
by NFC card emulation, reader/writer, and peer-to-peer mode;
2. NFC protocol stack: configure the NFC chip working mode and implement the NFC Forum
defined standards;
3. SE: the security chip, all of which involve sensitive data, encryption operations and other
services (such as bank cards, bus cards) require separate security chip processing;
4. SE access API: Opens the interface to the client for accessing the SE to perform functions such
as balance reading and over-the-air recharging;
5. SE access control: control and authorize SE access to ensure SE security;
6. The AP accesses the SE chip: When the client accesses the interface chip of the SE through
the application processor, the chip may also be different when the SE type is different. When the
SIM card is the SE, the chip is the Modem. The above different modules can be combined to
achieve different NFC functions, which can be roughly divided into two types: simple NFC and
NFC with SE:
Simple NFC refers to an NFC terminal that only has an NFC controller and an NFC protocol stack.
Since there is no SE, this terminal can only support the NFC reader and point-to-point functions
mentioned in the previous blog post, such as business card exchange and label reading. NFC
functions that are not related to security. Since the configuration is simple, and Android 2.3 or
more native systems have already implemented these functions, most NFC terminals currently on

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the market are such simple NFC. Compared to simple NFC, an NFC terminal with SE integrates a
separate security chip SE. In addition to the reader and peer-to-peer mode, it supports the
security applications introduced by the card emulation mode (such as bank cards, bus cards, etc.)
and can support The non-contact card swiping on the POS machine can also support the client's
access to the SE, realizing the functions such as reading the balance of the bank card and the bus
card stored in the SE, and recharging the air.
There is no doubt that the NFC terminal with the SE function is currently more concerned with
users, operators, and banks. Different organizations adopt different SE methods when promoting
NFC terminals. At present, there are mainly three types of SE, namely, SIM cards. The terminal's
built-in SE chip and MicroSD card represent the operators, terminal manufacturers, and the
bank's position in the industry chain, as well as the natural response to the initial stage of the
NFC terminal. It should be said that from the current development situation, the NFC terminal
solution promoted by the SIM card as the SE (known as the SWP program) is the fastest-growing
and is led by the operators' organization GSMA, with more than 50 operations in the world.
Traders (including China Mobile, China Unicom, and major operators in Europe, the United States,
and Japan and South Korea) announced their support for the program. Currently, nearly 40
million terminals are sold globally, and it is expected that there will be continuous development
in 13 years. In the follow-up, we will discuss the protocols supported by the NFC terminal in the
most mainstream NFC terminal solution (SWP solution) using the SIM card as the SE. The
NFC-SWP terminal refers to an NFC terminal that supports an SWP-SIM card, that is, an NFC
terminal that uses a SIM card as an SE.
NFC-SWP terminal architecture
(a) NFC non-contact part
The NFC Controller, NFC protocol stack and SIM card in Figure 1 provide NFC card emulation,
reader/writer, and peer-to-peer functions. The SIM card functions mainly as a security module in
the card mode. Currently, the SIM card functions as a reader and peer-to-peer. The mode has not
played a role. The information routing mechanism of the NFC terminal is different in different
modes. When the NFC terminal works in the card emulation mode, the signal sent by the
external POS machine will be forwarded to the SIM card through the NFC Controller for
processing. When the NFC terminal works in the reader, peer-to-peer In the mode, the
information read from the external card or mobile phone will be forwarded to the NFC protocol
stack through the NFC Controller for analysis, and finally transferred to the operating system or
client application for processing.
The technical standards and test standards of the NFC non-contact part are relatively complete,
mainly completed by ISO, NFC Forum, ETSI and other standardization organizations, among
which:
l The ISO is mainly responsible for the underlying analog and digital protocols of the NFC air
interface. The ISO-defined RF protocol has been widely used in public transportation, banking,
government, and other industries.
l The main mission of the NFC Forum is to define new types of NFC devices and ensure their
interoperability. The NFC Forum mainly defines the data structures and link layer protocols
required for data exchange between the new NFC devices on top of the ISO protocol.

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l ETSI is mainly responsible for formulating the interface specifications of NFC Controller and SE.
The interface specifications originally developed by ETSI were limited to SIM cards, but it has
been widely used as a common interface specification in other forms of SE.
The standards of NFC are relatively complex, and the standards followed in different NFC modes
of operation are not the same. The following are the protocols that should be followed under
different modes.
Mode Radio Protocol Intermediate Protocol (1) Application Protocol Other Protocols Application
Scene Card Simulation Mode ISO 14443 No industry specification (2) ETSI 102.613 (SWP) ETSI
102.622 (HCI) Compatible with existing devices Reader mode ISO 14443 No industry standard No
compatible Existing Equipment ISO 14443 NFC Forum Tag Type 1-4NFC Forum NDEFNFC Forum
RTD External Custom Application Protocol (3) Interworking with NFC Forum Devices Peer-to-Peer
Mode ISO 18092 NFC Forum LLCPNFC Forum SNEPNFC Forum RTD External Custom Application
Protocol Interworking with NFC Forum Devices :Intermediate protocol refers to the link layer and
data format protocol required for communication between NFC Forum devices. Note 2: Specified
by different industry standards, not within the NFC specification system, such as PBOC, EMV, etc.
Note 3: NFC RTD specifies URI, Contacts and other common applications, these applications can
be recognized by the Android system, do not require special client support; at the same time,
different application parties can also customize the application protocol, such as GPS location
sharing, but these own applications The protocol needs to be matched with private client
software to recognize.
From the above table, it can be seen that an NFC terminal can not only communicate with a
brand-new NFC Forum device that conforms to the NFC Forum protocol but also can be modeled
as a device that is the same as an ordinary non-contact IC card and can be read by a non-contact
POS. Therefore, it can be widely used in the existing non-contact environment that users are
familiar with and reduce the entry threshold for users. This is crucial for the promotion of a new
type of equipment in the initial stage.
(B) SIM card access interface
It consists of SE access API, SE access control, and Modem in Figure 1. The biggest difference
between a mobile phone and an ordinary non-contact IC card is that it has two parts: network
function and human-computer interaction. Therefore, NFC mobile phones can engage in rich
services that cannot be accomplished by traditional non-contact ICs, such as over-the-air
recharging and balance inquiry. All these services require a technical premise that a standard SIM
card access interface is needed to enable the application client to access the SIM card and
communicate with the applet in the SIM card. Specifically speaking, three standards need to be
supported in mobile phones:
1. SIM Alliance Open Mobile API: Provides application clients with channels for
communicating with SIM cards
2. Global Platform/GSMA: Secure Element Access Control: Authorizing Application Clients to
Access the Corresponding Applets in the SIM Card
3. Modem: It is required to fully support the 3GPP 27.007 standard, support the opening of
the logical channel of the SIM card, and enable the transparent transmission of the APDU on the
logical communication.

C&T RF Antennas Inc
 Jasmine Lu (86)17322110281
At present, related standardization in NFC-SWP terminals is performing well. There are also many
NFC-SWP mobile phones that already support these standards. However, in fact, due to the lack
of test standards and testing tools corresponding to the above three standards, NFC mobile
phones are currently facing SIM. Card access interface support is poor. The modem supports the
transparent transmission of APDUs on the logical channels. In particular, the Modem transmits
the APDUs specified in the ETSI 102.221 telecommunications standard. However, under the new
NFC mobile phone architecture, the Modem logical channels may also transmit data. APDUs in
banks, transit, etc. The definitions of these APDUs may differ from those of telecommunications
standards and may exceed the traditional knowledge of modem providers. Therefore, from the
current situation, on the one hand, mobile phones, especially Modem providers, need to be able
to fully understand the characteristics of the NFC service, especially the difference between the
logical channels and the traditional telecommunications applications and improve the product's
support for transparently transmitting APDUs on logical channels. On the other hand,
standardization organizations, operators, and manufacturers are also required to improve the
testing standards and testing tools to promote and ensure the maturity of products.
The radio frequency sine wave generated by the terminal transfers energy to the tag and then
reads the data from the tag. After NFC is started, a 13.56 MHz sine wave of the signal center
frequency is continuously generated. If there is a tag within the disturbance range of the
magnetic field generated by the sine wave, the tag will be energized by the disturbance of the
magnetic field to generate the wave of the original sine wave inverse frequency or change the
frequency attribute. The phone detects this change to know that there are tags nearby. RFID
communication at a close distance is often referred to as a near-pair system. The proximity
system usually ranges from 0 to 1 cm. This means that the tag is next to the reader or pressed on
the reader. The advantage of this close proximity is that the label's battery factory can emit a lot
of energy. This energy is sufficient to support tag communication without the need for a built-in
power supply. Near matchmaking also facilitates highly confidential situations. For example, an
NFC-enabled mobile phone with an integrated circuit capable of producing a 13.56 MHz radio
frequency with an encoder, a decoder, an antenna, a comparator, and transmitting energy to the
tag, and reading the modulation information in the backscatter hardware. The reader
continuously generates RF signals and observes the received RF signals to read the information.
NFC-enabled devices can exchange data in active or passive mode. In passive mode, a device that
initiates NFC communication also referred to as an NFC initiator device (master device), provides
an RF-field during the entire communication process, as shown in FIG. It can choose one of the
106kbps, 212kbps, or 424kbps transmission speeds to send data to another device. The other
device is called an NFC target device (slave) and does not have to generate a radio frequency field.
Instead, it uses a load modulation technique to transmit data back to the initiator at the same
speed.
The standard specifies an operating frequency of 13.56 MHz, which is an international
license-free universal frequency band and one of the 15/18 bands of the US ISM band. The data
transmission rate is 106, 212 or 424 kbps. Depending on the communication range, the
transmission rate is the maximum at 20 cm or about 8 inches. The actual communication range is
only a few inches or no more than 10 cm. The standard specifies a variety of operating modes.

C&T RF Antennas Inc
 Jasmine Lu (86)17322110281
In the active mode, either party to the communication can use the "listen before sending"
protocol to initiate a half-duplex transmission after the transceivers are powered on. This feature
can prevent conflicts when more than one NFC device attempts to access a reader, where one
device is the initiator and the other device is the target.
In passive mode, like an RFID tag, the target is a passive device. The tag obtains the working
energy from the magnetic field transmitted by the initiator and then transmits the data to the
initiator by modulating the magnetic field (post-scan modulation, a type of AM).
In use, NFC adopts a mechanism called listen before talk because the use of NFC usually
encounters spikes and avoids data link errors caused by simultaneous communication between
different initiators or targets. This mechanism will allow the initiating end device to detect the
strength of the external magnetic field to determine whether there is any other device in
communication before sending an inquiry signal. The realization of this mechanism is called RF
Collision Avoidance (RFCA). Its action behavior is Each time the originator issues an interrogation
signal, it will detect the external magnetic field. When the magnetic field strength exceeds the
threshold strength (H threshold = 0.1875A/m), the query will stop until the outside strength falls
below the threshold value. If it is lower than the critical value, it will start to send inquiry
commands. The detection time is TIDT+nTRFW, n is 0 to 3 probability sampling: TRFW=512/fc(RF
waiting time), TIDT >4096/fc(initial delay time ). When the initiating device does not detect a
magnetic field exceeding the threshold strength within the TIDT+nTRFW, it transmits an
unmodulated RF field of the TIRFG and then issues an interrogation signal, wherein TIRFG must
be greater than 5ms.
Since the NFC 106 kbps is 100% ASK modulation, the packet structure of the entire High/Low
signal has a fairly detailed definition. Several of these parameters ranged from 100% to 5% Am
time (t1), 5% Am duration (t2) and Am from 5% to 60% time (t4) overshoot. 212/424kbps is the
modulation rate of 8% to 30%.
RF test
RF test kit
1. Calibration coil: The function of the coil is to verify whether the signal emitted by the test
object is the correct intensity and modulation during the test. This Coil is a simple antenna
architecture. Of course, EMCA also specifies all dimensions. The value measured by the coil is
0.32V (RMS) = 1A/m (magnetic field strength).
2. Field Generating Antenna: kit is used to launch the magnetic field. The figure also contains
a set of antenna matching circuits.
3. Sense coil: sense coil is used to measure the magnetic field intensity and modulation of the
object to be measured.
4. Reference device: The reference device is used to test the DUT's standard parts.
RF test procedure
1. Initiate device power test:
This test item is to test whether the strength of the magnetic field supplied by the initiating
device supplies sufficient working power for the target.
The signal is adjusted by the generating antenna, and the measured intensity at the right end of
the calibration coil is Hmax (7.5 A/m). At this time, the reference device is adjusted to the power

C&T RF Antennas Inc
 Jasmine Lu (86)17322110281
test line to adjust C2 so that the line resonance point is at 19 MHz (this part is The specification
does not specify the reason for the adjustment to 19 MHz. It is inferred that if the 19 MHz can
achieve the 3V output, the voltage at the target of 13.56 MHz will definitely exceed 3 V, which is
due to its lower limit and is placed on the DUT. Position, the voltage value obtained by C3 is
adjusted by the line R2 to be 3V. At this point, the reference device has been completed, and
then the card is used to measure the initiating device, and the card is placed in the super working
range marked by the initiating device, and the voltage value measured at any position within the
super-operating range (C3). ) Do not exceed 3V. The Hmin test is roughly the same as max. The
difference is that the reference device resonant frequency is adjusted to 13.56 MHz and the
measured voltage value must exceed 3V.
2. Target load modulation test:
(1) Passive mode
● 106kbps: This test is to verify that the object can be correctly modulated waveform, first place
the calibration coil on the outer edge of the lower side, to determine the waveform and intensity
emitted by the generating antenna is correct, then the target to be measured is placed on On the
outer edge, edit a SENS_REQ waveform defined by an ECMA 340 to be emitted by the generating
antenna and send a SENS_RES signal back to the object to be measured. In this way, the signal
can be measured through the two sense coils. Since the load modulation signal is weak, the
voltage difference between the two sense coils is used for calculation. Due to compatibility issues,
the MiFARE continues to use the subcarrier modulation at 106 kbps as the passive target's return
signal. The measurement points should be fc+fs and FC-fs (fc=13.56 MHz, fs=fc/16).
● 212/424kbps: The high-speed modulation signal measurement method is very similar to
106kbps, except that the measurement acquisition position is changed to FC because no
subcarrier modulation is used at these two transmission speeds.
(2) Active mode
There is not much difference between the active mode test and the passive mode. Because it is
the active mode, the RF field emission time of the target object is measured, the time for the
command is issued, and so on.
3. Initiate the device's load modulation test: This test consists of verifying the modulation
mechanism of the initiating device. It can be divided into active mode and passive mode
reception.
(1) Active mode emission: The calibration coil is placed at any position defined by the initiator
device, and the measured waveforms are required to comply with ECMA340 specifications.
(2) Passive mode reception: This is the signal that the testing initiator can correctly receive the
passive target. Use the reference device made by the load modulation test circuit in Figure 7-2.
First, correct the relationship between the C3 voltage and the distance, and then test the card
and the device under test. The modulation signal sent by the device is received at the object side.
The only part of the test items can be discussed here. For the detailed test, please refer to ECMA.

NFC architecture and standards involved -C&T RF Antennas Inc

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