Near Field Communication (NFC): From Theory to Practice

1

Executive Summary

Near Field Communication (NFC) is a new technology and ecosystem that has emerged in the last decade. NFC technology is a short range, high frequency, low bandwidth and wireless communication technology between two NFC enabled devices. Communication between NFC devices occurs at 13.56 MHz high frequency which was originally used by Radio Frequency Identification (RFID). Although RFID is capable of reception and transmission beyond a few meters, NFC is restricted to within very close proximity. Currently, integration of NFC technology into mobile phones is considered as the most practical solution because almost everyone carries one.

NFC technology enables communication between an NFC enabled mobile phone at one end, and another NFC enabled mobile phone, an NFC reader or an NFC tag at the other end. Potential NFC applications and services making use of NFC technology include e-payment, e-ticketing, loyalty services, identification, access control, content distribution, smart advertising, data/money transfer and social services. Due to its applicability to a wide range of areas and the promising value added opportunities, it has attracted many academicians, researchers, organizations, and commercial companies.

The changes or improvements on RFID to expose NFC technology can be described as:

Short range communication, where RFID may use long range especially for active tags that contain embedded energy.

Passive tag usage only (actually occurs only in reader/writer mode) whereas both active and passive tags are possible in RFID.

Inherent secure data exchange because of short range communication.

Implicit matching of pairs that express their willingness to perform NFC communication by bringing themselves close to each other.

Interest from companies to integrate many services such as payment with debit and credit cards, loyalty, identification, access control and so on, because of the secure communication and implicit matching as described in the previous item.

Technology usage is now in the pilot phase in many countries. Usability issues and technology adoption are being explored by many academicians and industrial organizations. Many mobile phone manufacturers have already put their NFC enabled mobile phones into the market. As NFC enabled mobile phones spread and commercial services are launched, people will be able to pay for goods and services, access hotel rooms or apartments, update their information in social networks, upload their health data to hospital monitoring systems from their homes, and benefit from many more services by using their NFC enabled phones.

The success of NFC technology is bound to advances in other fields as well. Over-the-Air (OTA) technology among ecosystem actors is definitely a prerequisite to operate NFC systems satisfactorily. Secure Element (SE) is also a requirement to store valuable digital information and to provide concurrent execution of multiple NFC services on the same smart card securely. Dependence on other technologies is one of the challenges that NFC currently faces now.

Another important challenge is about the potential stakeholders in the NFC ecosystem. NFC has a complex and dynamic environment with high number of participating organizations. They have already recognized the possible added values, and each party is trying to maximize the value of their stake. The ownership and management of the SE is a dominant factor in getting a greater share, because each transaction has to use some applications installed on the SE, and the owner can always demand a higher share. Currently Mobile Network Operators (MNOs) own and issue the UICC as SE on mobile phones, and alternative SE ownerships are being negotiated among MNOs financial organizations, and even smart card manufacturers.

Please note that this chapter is an executive summary of the book and hence references are provided at the end of the related chapters.

1.1 Towards NFC Era

NFC is a technology that simplifies and secures the interaction with the automation ubiquitously around us. The NFC concept is designed from the synergy of several technologies including wireless communications, mobile devices, mobile applications and smart cards. Server side programming, web services, and XML technologies also contribute fast improvement and the spread of NFC technology. Many daily applications, such as credit cards, car keys, and hotel room access cards will presumably cease to exist because an NFC enabled mobile phone will suffice to provide all of their functionalities.

Currently, NFC is one of the enablers for ubiquitous computing. Therefore the origin of the idea is closely related to ubiquitous computing. In order to understand the relation of NFC and ubiquitous computing, we need to start with the history of ubiquitous computing.

1.1.1 Ubiquitous Computing

The essence of modern computers is automated calculation and programmability. The history of modern computers includes the work of pioneers over almost two hundred years. Personal Computers (PCs) are an important step after early computers, changing the way that a user interacts with computers by using keyboards and monitors for input and output instead of punch cards, cables and so on. The mouse has also changed the way humans and computers interact because it enabled users to input spatial data to a computer. The hand became accustomed to holding the mouse, and the pointing finger became accustomed to clicking it. The movements of the pointing device are echoed on the screen by the movements of the cursor, creating a simple and intuitive way to navigate a computer’s Graphical User Interface (GUI).

Touch screens changed the form of interaction dramatically. They removed the need for earlier input devices, and the interaction was performed by directly touching the screen, the new input device. In the meantime, mobile phones had been introduced, initially for voice communication. Early forms of mobiles contained a keypad. Mobile phones with touch screens can be assumed to be the state of the art technology as the same screen is used as both the input and output unit, allowing the user to act more intuitively.

Ubiquitous computing is the highest level of interaction between humans and computers, where computing devices are completely integrated into everyday life and the objects around, and are simple to use. Ubiquitous computing is a model in which humans do not design their activities according to the machines they need to use; instead, the machines adjust to human needs. Eventually, the primary aim is that humans using machines will not need to change their normal behaviors and also will not even notice that they are performing activities with the help of machines.

1.1.2 Mobile Phones

A mobile phone is an electronic device which is primarily used to make voice calls while the user is mobile. The user of the mobile phone must be registered to a mobile phone network where the service is provided by a MNO. The call can be made to or received from any other phone which is a member of either the same or another mobile phone network, a fixed line network, or even an internet based network. Mobile phones support the anytime, anywhere motto. Mobile phones are also referred to as mobiles.

Mobile phones are very convenient to use and handy. Therefore in addition to the voice call capability, a vast amount of additional services are bundled to it, and many new future services are still on the way, such as NFC technology. Currently supported mobile phone communication services can be viewed based on whether they are wired or wireless services. Mobile phones also include a vast amount of integrated services.

USB and PC synchronization are the most significant wired services. The phones are connected to the computers to enable data transfer, synchronization and so on.

The amount of wireless services, on the other hand, is much greater. GSM communication is obviously the primary service that a mobile phone provides. As a matter of fact it was the one that the pioneer phones provided. Later, Short Messaging Service (SMS) was introduced. Multimedia Messaging Service (MMS) could be enabled only after high data transfer rates between the base stations and the mobile phones. Moreover, users can experience mobile radio and television services with mobile phones. Localization services, specifically Global Positioning System (GPS), allowed phones to enable applications such as navigation and social media interaction. One added communication capability to mobile phones is via several peer-to-peer services such as Infrared, Bluetooth, and finally NFC. Infrared requires line of sight, NFC requires very close interaction, namely touching, and Bluetooth requires communication within small distance. Wi-Fi connectivity allowed mobile phones to access the Internet with low bandwidth. Electronic mail (e-mail) enabled users to access their inboxes or send e-mails while mobile.

Storing contact and communication details are the most important integrated services, since they simplify Global System for Mobile Communications (GSM). There are other integrated services that are not related to GSM, at least not directly. Instead, the main objective of those services is to eliminate additional devices and integrate all into one device. Calculator is one primitive function and eliminates the physical need for a calculator. Gaming is the one that most people like to have in their mobiles. Taking photos and videos, and even editing them using additional applications are simple to use so that additional cameras or video recorders are not required. Music and video playback are two other attractive facilities. Moreover, clock and alarm capability has removed the need for watches.

Some major wireless services currently enabled by mobile phones are GPS Navigation, Wireless Internet services, GSM, Bluetooth, Wi-Fi, and NFC technologies.

1.1.3 Technological Motivation of NFC

The main motivation for NFC is the integration of personal and private information such as credit card or debit card data into mobile phones. Therefore, security is the most important concern, and the wireless communication range provided even by RFID technology is considered too long. Mechanisms such as shielding are necessary to prevent unauthorized people from eavesdropping on private information because even non-powered, passive tags can be read over 10 m. This is where NFC comes in.

1.1.4 Wireless Communication, RFID, and NFC

Wireless communication refers to data transfer without using any cables. When communication is impossible and impractical for cable usage, wireless communication is the solution. The communication range may vary from a few centimeters to many kilometers. Wireless is generally mobile, and mobile is essentially wireless. We also distinguish nomadic communication from mobile. Devices that allow nomadic communication may perform either wireless or wired communication at a given time. An example of nomadic communication is the laptop.

The direct consequence of wireless communication is mobility. Mobility allowed people to be flexible, since they can be reached anywhere. It is obvious that mobility increased productivity, since mobile communication enabled people to be reached at anytime and anywhere. This has a big impact on our daily lives. People become reachable not only for commercial purposes, but also for social reasons. The currently available mobile communication services that support mobility are GSM, Bluetooth, Wi-Fi, WiMAX, and ZigBee.

1.2 Evolution of NFC

NFC can be taught as an extension to RFID that also uses smart card technologies’ interfaces. To understand NFC technology, we need to have a brief knowledge of the forerunners of NFC technology: the barcode as an earlier form of RFID technology, RFID, and the magnetic stripe card as an earlier form of smart cards and smart card technologies.

1.2.1 Earlier Form of RFID: Barcode Technology

A barcode is a visual representation of data of the object to which it is attached. The information on the barcodes is scanned by barcode readers and transferred to the computing devices that are connected to the readers. Then the device processes the information.

Early barcodes represent data by varying the widths and spacing of parallel lines, and are referred to as linear or one-dimensional (1D). Due to the used space, minimum thickness of each bar and orientation restrictions, the maximum addressable 1D code is not high. In contrary to limited number of available 1D codes, later two-dimensional (2D) barcodes evolved which have a larger data storage capacity. As an example, 2D barcodes on a medicine box may contain specific identification information for that medicine box, so each specific patient and each specific medicine can be tracked.

Some major examples of linear barcodes are UPC (Universal Product Code) and EAN13 (European Article Number) Barcodes. Also QR (Quick Response) Code Barcode is an example of a 2D barcode.

1.2.2 RFID Technology

RFID is a technology that uses communication via radio waves to exchange data between an RFID reader and an electronic RFID tag (label), traditionally attached to an object, mostly for the purpose of identification and tracking. The data transmission results from electromagnetic waves, which can have different ranges depending on the frequency and the magnetic field.

RFID tags are small integrated circuits which can hold small applications as well as tiny amount of data. There are two types of RFID tags; passive tags and active tags. Passive tags have no internal power supply, have an IC (Integrated Circuit) and antenna embedded in them. They are powered by the incoming signal from a Radio Frequency (RF) field. Passive tags have practical read distances ranging from about 10 cm up to a few meters depending on the chosen RF and antenna design and size. Unlike passive RFID tags, active RFID tags have their own internal power source which is used to power any ICs that generate the outgoing signal. Active tags are typically much more reliable than passive tags due to the ability to conduct a session with a reader at longer distances. The major drawback of RFID tags when compared with paper barcodes is their higher price.

Both barcodes and RFID tags can be copied, however in different ways. Barcodes can be distributed electronically which enables printing and displaying on a digital device such as a PC or a mobile phone. You can e-mail a barcode image to a vast number of people and all of the receivers can print the barcode onto ordinary paper immediately. RFID tag content can be electronically spread as well. However, a digital chip is required for each copy instead of paper. When compared with barcodes, producing the original as well as copies is more expensive. The RFID tag has large data capacity, and each individual tag has a unique code which is similar to 2D barcodes. The uniqueness of RFID tags provides a product that can be tracked as it moves from one location to another.

RFID was a relatively early technology, and many RFID applications have been developed so far. Some of those applications are as follows:

Inventory control: Most RFID applications are for managing assets. Retail stores use RFID tags on their items to control purchase, decrease in inventory and so on.

Toll roads: Active RFID tags are fixed on vehicles so that during the vehicle’s journey, the toll cost can easily be deducted from the owner’s account.

Public transportation: Many cities use RFID enabled payment systems on public transportation to make payment easier.

Passports: It has become an ordinary process to insert RFID tags into passports to prevent counterfeiting them. Information such as owner’s photo, fingerprint, address, some private data and so on are embedded into the tag, so that modification and illegal usage is harder than using printed material alone.

1.2.3 Earlier Form of Smart Cards: Magnetic Stripe Cards

A magnetic stripe card is one that contains a digital storage space where the data are loaded during the manufacturing phase. The stripe is made up of tiny magnetic particles in a resin. It is traditionally a read-only item. It is read by physical contact by swiping the card past a device with a magnetic reading head. Currently, magnetic stripes are mostly used on bank debit and credit cards, loyalty cards, airline tickets and boarding passes.

1.2.4 Smart Card Technology

A smart card is an item that contains an embedded IC that has integrated memory, which mostly involves a secure microcontroller or an equivalently intelligent device. In terms of mechanism, smart cards can be considered in three groups; contact and contactless smart cards, and hybrid models.

Smart cards do not contain any power source; hence energy is supplied by the external device, or the reader that the card interacts with. Contact cards receive the required energy via physical contact whereas contactless cards receive power via an electromagnetic field.

A contact smart card communicates with a card reader by direct physical contact, whereas a contactless smart card uses an RF interface for the same purpose. Contact smart cards contain a micro module containing a single silicon IC card with memory and microprocessor. An external device provides a direct electrical connection to the conductive contact plate when the contact smart card is inserted into it. Transmission of commands, data, and card status information takes place over these physical contact points.

In the case of contactless smart cards, the communication is performed only when the devices are in close proximity. One reason for this is increasing security of the communication, and another is enabling higher energy transfer from the active (the device that has embedded power source) to the passive device. As a contactless smart card is brought within the electromagnetic field range of the smart card reader, the card reader spreads out an electromagnetic signal and the smart card is powered by the signal. Once the smart card is powered, it can respond to the request of the reader.

The three major contactless smart cards are ISO/IEC 10536 Close Coupling Smart Cards, ISO/IEC 14443 Proximity Coupling Smart Cards and ISO/IEC 15693 Vicinity Coupling Smart Cards. Close coupling smart cards operate at a distance of up to 1 cm, and proximity coupling smart cards operate at a distance of less than 10 cm (less than 4 in.) at 13.56 MHz. Vicinity coupling smart cards operate in a range of up to 1 m at 13.56 MHz, such as those used in access control systems.

The popular cards are the proximity contactless smart cards which enable a wide range of usage in a wide range of areas from health to entertainment. Various proximity coupling smart card technologies have emerged; however, only a few of them have become ISO/IEC 14443 standard which also provides interface for NFC transactions depending on the operating modes. Currently, the most famous and competing proximity contactless smart cards are MIFARE, Calypso, and FeliCa.

(i) MIFARE

MIFARE is a well-known and widely used 13.56 MHz contactless proximity smart card system that is being developed and is owned by NXP Semiconductors which is a spin-off company of Philips Semiconductors. MIFARE is ISO/IEC 14443 Type A Standard. Today, MIFARE is used in more than 80% of all contactless smart cards in the world.

(ii) Calypso

Calypso is an international electronic ticketing standard for a microprocessor contactless smartcard, originally designed by a group of European transit operators from Belgium, Germany, France, Italy and Portugal. It ensures multi-sources of compatible products, and makes possible the interoperability between several transport operators in the same area.

(iii) FeliCa

FeliCa is a 13.56 MHz contactless proximity high speed smart card system from Sony and is primarily used in electronic money cards. However, FeliCa did not become an ISO/IEC standard.

1.2.5 NFC as a New Technology

NFC operates between two devices over a very short communication range. NFC communication uses the 13.56 MHz spectrum as in RFID. Currently data transfer speed options are 106, 212, and 424 kbps. NFC technology operates in different operating modes; reader/writer, peer-to-peer, and card emulation where communication occurs between an NFC mobile on one side, and a passive RFID tag (NFC tag), an NFC mobile or an NFC reader on the other side. NFC technology is compared with the other technologies in terms of data transfer rate in Chapter 2, Figure 2.23. One of the NFC technology’s major properties is its implicit security because of short communication distance. Close proximity of two devices makes the signal interception probability very low. The other property is the automatic implicit pairing capability of NFC. An installed application on a mobile device is automatically launched when it finds the matching pair.

1.3 NFC Essentials

As the basics of the used technology are provided above, we can now introduce essential NFC technical details. In order to do this, NFC structure and the NFC devices (NFC tag, NFC reader, and NFC mobile) must be explained in enough detail. The communication is based on the existing standards, and the devices stick to those standards for a seamless activation. Hence, we also will provide information on the standardization bodies which steer NFC technology.

1.3.1 Smart NFC Devices

NFC devices are the acting components of NFC. NFC is available using three NFC devices: the NFC mobile, NFC reader and NFC tag.

NFC enabled mobile phone: NFC enabled mobile phones which are also referred to as NFC mobiles are the most important NFC devices. Currently, integration of NFC technology with mobile phones (thus introducing NFC enabled mobile phones) creates a big opportunity for the ease of use and acceptance of the NFC ecosystem.

NFC reader: An NFC reader is capable of data transfer with an NFC component. The most common example is the contactless POS (Point of Sale) terminal which can perform contactless NFC enabled payments when an NFC device is touched against the NFC reader.

NFC tag: An NFC tag is actually an RFID tag that has no integrated power source.

NFC works in a very intuitive way. Two NFC devices immediately start their communication as they are touched. The touching action is taken as the triggering condition for NFC communication. This is actually an important feature of NFC technology. In the NFC case, the NFC application is designed so that when the mobile touches some NFC component with the expected form of data, it boots up. Hence, the user does not need to interact with the mobile device after she touches one appropriate NFC device which may be an NFC tag, an NFC reader, or another NFC enabled mobile phone. This is a very useful property of NFC communication that provides ubiquitous computing.

For each NFC communication session, the party that starts or initiates the communication is called the initiator, whereas the device that responds to the requests of the initiator is called the target. This case is analogous to the well-known client server architecture. Remember that in a client server communication the client initiates the communication and the server responds. In NFC communication, it is no different.

In an active/passive device approach, when an NFC component has an embedded power source, it can generate its own RF field, and naturally initiates and leads communication. This device is called an active device. On the other hand, if it does not have any embedded power source, it is called a passive device and can only respond to the active device.

The initiator always needs to be an active device, because it requires a power source to initiate the communication. The target, however, may be either an active or a passive device. If the target is an active device, then it uses its own power source to respond; if it is a passive device, it uses the energy created by the electromagnetic field which is generated by the initiator that is an active device.

Consider an NFC tag which is a low cost and low capacity device. It does not contain any power source and needs an external power source to perform any activity. Thus, an NFC tag is always a passive device and always a target, since it does not include any energy source by design. It stores data that can be read by an active device.

1.3.2 Standardization of NFC Enabled Mobile Phones

NFC technology was jointly developed by Philips and Sony in late 2002 for contactless communications. Europe’s ECMA International adopted the technology as a standard in December 2002. The International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC) adopted NFC technology in December 2003. In 2004, Nokia, Philips, and Sony founded the NFC Forum to promote the technology. NFC technology standards are acknowledged by ISO/IEC (International Organization for Standardization/International Electrotechnical Commission), ETSI (European Telecommunications Standards Institute), and ECMA (European Computer Manufacturers Association).

NFC is a joint adventure of various technologies. Smart cards, mobile phones, card readers, short range communication, secure communication, transaction and payment systems are the most significant leading technologies. As several technologies are involved, related organization bodies have provided the respective standards. The integrated form of those standards will hopefully define a common vision for secure and yet functional usage and transaction. An interoperable set of standards is essential for a successful NFC ecosystem. The most dominant standardization organizations are:

(i) NFC Forum

NFC Forum is an alliance for specifying the NFC standards built on ISO/IEC standards. NFC Forum was established with the aim of enabling NFC technology and making it spread throughout the world. NFC Forum is a non-profit industry association formed to improve the use of NFC short range wireless interaction in consumer electronics, mobile devices, and PCs. NFC Forum promotes implementation and standardization of NFC technology to ensure interoperability between devices and services. The mission of the NFC Forum is to promote the usage of NFC technology by developing specifications, ensuring interoperability among devices and services, and educating the market about NFC technology.

NFC Forum has standardized two operating modes (reader/writer and peer-to-peer operating modes) up to now. Record Type Definition (RTD) and NFC Data Exchange Format (NDEF) specifications are provided by NFC Forum for reader/writer mode communication. Within peer-to-peer mode, Logical Link Control Protocol (LLCP) is used to connect peer-to-peer based application to the RF layer. Card emulation mode on the other hand, provides smart card capability for mobile phones.

Another important development introduced by NFC Forum is the N-Mark trademark which is a universal symbol for NFC, so that consumers can easily identify where their NFC enabled devices can be used.

(ii) GlobalPlatform

GlobalPlatform is a cross industry, non-profit association which identifies, develops and publishes specifications that facilitate secure and interoperable deployment and management of multiple embedded applications on secure smart cards. The goal of the GlobalPlatform specifications is to ensure interoperability on content management of smart cards, managing smart cards without any dependencies on hardware, manufacturers, or applications.

(iii) GSM Association (GSMA)

GSMA is an association of mobile operators and related companies devoted to supporting the standardization, deployment and promotion of GSM. GSMA represents the interests of the worldwide mobile communications industry. GSMA is focused on innovating, incubating and creating new opportunities for its members, all with the ultimate goal of driving the growth of the mobile communications industry.

(iv) ISO/IEC

ISO is the world’s largest developer and publisher of international standards. It is a non-governmental organization that forms a bridge between the public and private sectors. IEC is a non-profit international organization that prepares and publishes international standards for all electrical, electronic and related technologies. ISO and IEC work together to provide worldwide standards.

(v) ECMA International

ECMA International is an international non-profit standardization organization for information and communications systems. ECMA studies include mobile devices and NFC.

(vi) ETSI and ETSI Smart Card Platform (ETSI SCP)

ETSI is a non-profit organization with 700+ members. The ETSI produces globally applicable standards for Information and Communications Technologies (ICT), including fixed/mobile, radio, broadcast and Internet technologies. ETSI SCP handles Subscriber Identity Module (SIM) specifications that would enable SIM cards to carry NFC applications or to play other roles within NFC phones.

(vii) Java Community Process (JCP)

JCP holds the responsibility for the development of Java technology which indeed is a prominent candidate for NFC applications as well. As an open, inclusive organization of active members and non-member public input, it primarily guides the development and approval of Java technical specifications.

(viii) Open Mobile Alliance (OMA)

OMA develops open standards for the mobile phone industry. OMA members include many companies including the world’s leading mobile operators, device and network suppliers, information technology companies and content and service providers.

(ix) 3rd Generation Partnership Project (3GPP)

3GPP is a collaboration between groups of telecommunications associations to make a globally applicable third generation (3G) mobile phone system specification. 3GPP specifications are based on evolved GSM specifications.

(x) EMVCo

EMVCo aims to ensure global interoperability between chip cards and terminals on a global basis regardless of the manufacturer, the financial institution or the card issuer. EMV 2000 specifications are an open standard set for smart card based payment systems worldwide and seek collaboration in mobile payment standards.

1.3.3 General Architecture of NFC Enabled Mobile Phones

Mobile devices those are integrated with NFC technology contain NFC specific ICs such as SEs and an NFC interface (see Chapter 3, Figure 3.7). The NFC interface is composed of an analog/digital front-end called an NFC Contactless Front-end (NFC CLF), an NFC antenna and an NFC controller to enable NFC communication. The NFC controller enables NFC communication of the mobile phone with the external NFC device. An NFC enabled mobile phone requires an SE for performing secure transactions with the external NFC devices. The SE provides a secure environment for related programs and data. It enables storage of sensitive data of the user. It also enables secure storage and execution of NFC enabled services such as contactless payments. Various standards have already been defined for NFC communication between two NFC enabled devices, and data transfer within the NFC mobile phone such as Single Wire Protocol (SWP) or the NFC Wired Interface (NFC-WI).

The host controller can be identified as the heart of any mobile phone. A Host Controller Interface (HCI) creates a bridge between the NFC controller and the host controller. The HCI is a logical interface which allows an NFC interface including front-end to communicate directly with an application processor and multiple SEs in mobile devices.

1.3.4 Near Field Communication Interface and Protocol (NFCIP)

At the physical layer, the Near Field Communication Interface and Protocol (NFCIP) is standardized in two forms as NFCIP-1 which defines the NFC communication modes on the RF layer and other technical features of the RF layer, and NFCIP-2 which supports mode switching by detecting and selecting one communication mode.

(i) Near Field Communication Interface and Protocol-1 (NFCIP-1)

NFCIP-1 standard defines two communication modes as active and passive. It also defines RF field, RF communication signal interface, and general protocol flow. Moreover, it defines transport protocol including protocol activation, data exchange protocol with frame architecture and error detecting code calculation (CRC for both communication mode at each data rate), and protocol deactivation methods.

(ii) Near Field Communication Interface and Protocol-2 (NFCIP-2)

NFCIP-2 standard specifies the communication mode selection mechanism and is designed not to disturb any on-going communication at 13.56 MHz for devices implementing NFCIP-1, ISO/IEC 14443 and ISO/IEC 15693.

1.4 NFC Operating Modes and Essentials

Remember that there may three major smart devices in NFC; NFC enabled mobile phones, NFC readers, and NFC tags. NFC communication occurs between two NFC devices with some valid combinations. For example, a mobile phone may communicate with an NFC reader.

As NFC occurs within a very close range, it is very common to touch the communicating devices against each other. For this reason, this process is called touching paradigm. User awareness is definitely a must in order to perform NFC. The user first interacts with a smart object (that is either an NFC tag, NFC reader, or another NFC mobile) using a mobile phone (see Chapter 4, Figure 4.3). After the touching activity occurs, the mobile device may make use of the received data and use mobile services as well, such as opening a web page, making a web service connection and so on.

1.4.1 NFC Operating Modes

There are three operating modes, reader/writer, peer-to-peer, and card emulation, as already mentioned. The reader/writer mode enables one NFC mobile to exchange data with one NFC tag. The peer-to-peer mode enables two NFC enabled mobiles to exchange data with each other. In card emulation mode, a mobile phone can be used as a smart card to interact with an NFC reader. Each operating mode has a different technical infrastructure as well as benefits for the users.

(i) Reader/writer mode

This mode provides communication of an NFC mobile with an NFC tag. The purpose of the communication is either reading or writing data from or to a tag by the mobile phone. We can further categorize the mode into two different modes: reader mode and writer mode. In reader mode, the mobile reads data from an NFC tag; whereas in writer mode, the mobile phone writes data to an NFC tag.

(ii) Peer-to-peer mode

Two NFC mobiles using this mode exchange any data between each other. Since both mobiles have integrated power, each one uses its own energy by being in active mode in this mode. Bidirectional half duplex communication is performed in this mode similar to other modes, meaning that when one device is transmitting, the other has to listen and can start transmitting data after the first one finishes.

(iii) Card emulation mode

This mode provides the opportunity for an NFC mobile to function as a contactless smart card. Some examples of emulated contactless smart card are credit cards, debit cards, loyalty cards and so on. One NFC mobile may even store multiple contactless smart card applications concurrently. The card emulation mode is an important mode since it enables payment and ticketing applications and is compatible with existing smart card infrastructure.

1.4.2 Reader/Writer Mode Essentials

As already mentioned, the underlying technical architecture of each mode differs. The standards and specifications used by each mode may also differ. In reader/writer operating mode, an active NFC enabled mobile phone initiates the wireless communication, and can read and alter data stored in NFC tags. First, the used RF interface in this mode is compliant to ISO/IEC 14443 Type A, Type B and FeliCa schemes which are contactless smart card interfaces (see Chapter 3, Figure 3.24). The applications operating in reader/writer mode usually do not need a secure area in the NFC enabled mobile phone; the process is only reading data stored inside the tag and writing data to the tag.

In this operating mode, NFC Forum performed various specifications and standards in tag types, operation of tag types, and data exchange format between devices. An NFC enabled mobile phone is capable of reading NFC Forum mandated tag types. Four tag types have been defined by NFC Forum, and are designated as Type 1, Type 2, Type 3 and Type 4. Each tag type has a different format and capacity. NFC tag type formats are based on either ISO 14443 Type A, ISO 14443 Type B, or Sony FeliCa.

The other important standard is the NDEF. NDEF is a data format to exchange information between two NFC devices; namely, between an active NFC mobile and a passive tag, or an active NFC mobile and an active NFC mobile.

NDEF is a binary message format designed to encapsulate one or more application-defined payloads into a single message construct. An NDEF message contains one or more NDEF records and those records can be chained together to support larger payloads. Various record types for NDEF messaging format are defined by NFC Forum for specific cases; smart posters, URIs, digital signature, and text.

The record types defined for smart posters are the most used. For example, with the defined smart poster record types, URLs, SMSs or phone numbers can be put on an NFC Forum mandated tag. By touching an NFC device to the tag, this information can be read and processed afterwards. The smart poster contains data that will trigger an application in the device such as launching a browser to view a website, sending an SMS to a premium service to receive a ring tone, and so on.

1.4.3 Peer-to-Peer Mode Essentials

In peer-to-peer mode, two NFC enabled mobile phones establish a bidirectional, link level connection to exchange information as depicted in Chapter 3, Figure 3.29. They can exchange virtual business cards, digital photos, and any other kind of data or perform Bluetooth pairing, and so on. Peer-to-peer operating mode’s RF communication interface is standardized by ISO/IEC 18092 as NFCIP-1. Also NDEF message is used in this mode which is received over LLCP that is also defined by NFC Forum. The data format is the same as that used in reader/writer mode.

LLCP as a data link layer protocol supports peer-to-peer communication between two NFC enabled devices which is essential for any NFC application that involves a bidirectional communication. LLCP specification defines five major services: connectionless transport, connection oriented transport, link activation-supervision-deactivation, asynchronous balanced communication and protocol multiplexing.

1.4.4 Card Emulation Mode Essentials

In card emulation mode, an NFC enabled mobile phone acts as a smart card. Either an NFC enabled mobile phone emulates an ISO 14443 smart card or a smart card chip integrated in a mobile phone is connected to the antenna of the NFC module. When the user touches the mobile phone to an NFC reader, the NFC reader initiates the communication. This operating mode is useful for secure transactions such as contactless payment, ticketing applications and access control.

As depicted in Chapter 3, Figure 3.32, when an NFC reader interacts with an NFC device, the NFC device acts like a standard smart card, thus the NFC reader interacts with the SE and its applications. Only the card emulation mode uses an SE efficiently and performs functions securely.

1.4.5 Case Studies

We present the following three case studies at the end of Chapter 4 to clarify the three operating modes and their usages thoroughly:

1. The NFC enabled shopping system enables users to shop online anywhere they want, so that no geographical restrictions are set. This use case employs the reader/writer mode.

2. The NFC based gossiping application works in the same way as gossiping and disseminates information between the parties. This use case employs the peer-to-peer mode.

3. The cinema ticketing application enables payment to be made. This use case employs the card emulation