**3. RFID-games proposal**

The main objective of the project was to develop educational games for children that offer easy interaction based on RFID. For this purpose, the advantages offered by games devel‐ oped in the pre-computer age (traditional games) were combined with the advantages and benefits of computer games.

To begin with, there are many advantages of traditional games. These were designed and carried out in the physical world with the use of real-world properties such as physical ob‐ jects, our sense of space, and spatial relations.

Pre-computer games interactions consisted of two elements: user-to-physical-world interac‐ tion and user-to-user interaction. The physical objects were easily assimilated by the chil‐ dren, allowing users to interact intuitively with them.

There are also many benefits of computer games. These are more popular than traditional games. Some the advantages are the following:


Taking advantage of real physical objects and the benefits that new technologies offer us, we have designed a new way to interact with the system. It is based on physical objects that in‐ tegrate RFID technology and allow us to interact with Graphics User Interfaces.

This kind of the system functions as follows: in the main game an interface is projected on the wall. Users with physical interfaces, i.e., the objects that integrate RFID tags, can interact with the main interface; this requires the mobile device that incorporates the RFID reader to interact with the main interface, which is necessary to bring objects to the mobile device (See Figure 1).

**Figure 1.** Digitized objects with RFID tags that communicate with the game's interface through the mobile device.

Due to the need to make a simple, accessible and intuitive system and considering the multi‐ ple technologies used to develop it, it was decided to follow an architecture based on three layers. The system infrastructure is divided in the following layers: Application Layer, Net‐ work Layer and Perception Layer. In the next section, we explain the latter in more detail (See Figure 2).

#### **3.1. Presentation layer**

The advantages offered by these devices and systems are numerous. They enhance positive attitudes in users. They feel more motivated and encouraged to learn. However, the systems

**•** The user needs a minimum knowledge of computer use. Not everybody can use a com‐ puter and some devices, like a mouse or a keyboard are not intuitive for people with cog‐

**•** The system requires highly specialized hardware / software which can be expensive (sim‐ ulators, virtual reality). In some games, impaired users may have difficulties finding spe‐

On the other hand, RFID technology has many benefits over other identification technolo‐ gies because it does not require line-of-sight alignment, tags can be identified simultaneous‐ ly, and the tags do not destroy the integrity or aesthetics of the original object. Due to the low cost of passive RFID tags and the fact that they operate without a battery, this technolo‐ gy is ideal for converting a real object in a physical interface capable of interacting with oth‐

The main objective of the project was to develop educational games for children that offer easy interaction based on RFID. For this purpose, the advantages offered by games devel‐ oped in the pre-computer age (traditional games) were combined with the advantages and

To begin with, there are many advantages of traditional games. These were designed and carried out in the physical world with the use of real-world properties such as physical ob‐

Pre-computer games interactions consisted of two elements: user-to-physical-world interac‐ tion and user-to-user interaction. The physical objects were easily assimilated by the chil‐

There are also many benefits of computer games. These are more popular than traditional

**•** People create the illusion of being immersed in an imaginative virtual world with com‐

**•** Computer games are typically more interactive than traditional games, which enables the

**•** Computer games allow feedback to be easily shown, as well as notifications about the

present the following disadvantages:

328 Radio Frequency Identification from System to Applications

cific information.

**3. RFID-games proposal**

benefits of computer games.

puter graphics and sound.

user to feel more motivated.

jects, our sense of space, and spatial relations.

games. Some the advantages are the following:

dren, allowing users to interact intuitively with them.

game process and other important information.

er devices

nitive disabilities. They need someone to help them.

This layer is the intermediary between the user and the system. Its main function is to allow the user to easily interact with the system. In our case study, the games are designed for children and users with special needs and for this reason we must focus primarily on usabil‐ ity and accessibility of the system. The main requirements that have been followed for the development of this type of games are:

Designing simple interfaces so that users do not have to learn to use it, acquire new skills, or need help.

Avoiding distraction and facilitating the interaction so that the user need not know and memorize how the system works.

without that them being aware of it. In this particular case, a mobile device has been cam‐ ouflaged in a toy in such a way that it is more engaging and intuitive to users. The devi‐

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Mobiles devices: These devices internally incorporate the RFID reader, allowing users to

Projector: This shows the game user interface, the results and feedback. The software is run on a PC or laptop. It returns the information in textual and audio format to facilitate the use of games. It works dynamically and responds to the information sent to web services (Ap‐

The user communication style with the device is very intuitive, which is why no prior knowledge is necessary (see Figure 3), it is only necessary to move the toy, card or object, depending on the game, closer to the mobile device (hidden in an object). The interaction

In this case, the collaborative screen shows the game which is being executed. It may show some objects and to associate that object the user has to interact with it, just by moving the corresponding object closer to the mobile device. From this moment all processes are run implicitly. The collaborative screen displays the pictures, text and sounds, depending on the

**Figure 3.** Interaction. The user brings the digitized object closer (interaction resource) to the mobile devices that con‐

tain the RFID Reader. This is an interaction device hidden in an object [27].

ces available in the system are described as following:

communicate with the system through RFID technology.

game executed.

plication Layer) through the communication network (Network Layer).

and the processes that occur below the system are implicitly run by the user.

Avoiding fear of interacting with the system, as well as providing notification of game de‐ velopment and the collaboration of information among players.

**Figure 2.** System architecture divided into three layers: Perception, Network and Application

This layer is divided into two parts. Firstly, there are the objects that integrate RFID technol‐ ogy, also called interaction resources, and secondly, there are interaction devices, through which are offered relevant services.


without that them being aware of it. In this particular case, a mobile device has been cam‐ ouflaged in a toy in such a way that it is more engaging and intuitive to users. The devi‐ ces available in the system are described as following:

Avoiding distraction and facilitating the interaction so that the user need not know and

Avoiding fear of interacting with the system, as well as providing notification of game de‐

velopment and the collaboration of information among players.

**Figure 2.** System architecture divided into three layers: Perception, Network and Application

which are offered relevant services.

ciates the object with its function.

This layer is divided into two parts. Firstly, there are the objects that integrate RFID technol‐ ogy, also called interaction resources, and secondly, there are interaction devices, through

**•** Objects. Their main function is to facilitate the human-computer interaction. These re‐ sources need to have a RFID reader nearby to perform services. The main reason to use objects that interact with the environment is the following: The user uses human factors such as perception in order to interact with the environment. When an object similar to other objects with similar appearance is seen, the mind of the user automatically asso‐

**•** Devices. These computing devices are used as input and output of a system. They are communication channels. They are responsible for obtaining information from users

memorize how the system works.

330 Radio Frequency Identification from System to Applications

Mobiles devices: These devices internally incorporate the RFID reader, allowing users to communicate with the system through RFID technology.

Projector: This shows the game user interface, the results and feedback. The software is run on a PC or laptop. It returns the information in textual and audio format to facilitate the use of games. It works dynamically and responds to the information sent to web services (Ap‐ plication Layer) through the communication network (Network Layer).

The user communication style with the device is very intuitive, which is why no prior knowledge is necessary (see Figure 3), it is only necessary to move the toy, card or object, depending on the game, closer to the mobile device (hidden in an object). The interaction and the processes that occur below the system are implicitly run by the user.

In this case, the collaborative screen shows the game which is being executed. It may show some objects and to associate that object the user has to interact with it, just by moving the corresponding object closer to the mobile device. From this moment all processes are run implicitly. The collaborative screen displays the pictures, text and sounds, depending on the game executed.

**Figure 3.** Interaction. The user brings the digitized object closer (interaction resource) to the mobile devices that con‐ tain the RFID Reader. This is an interaction device hidden in an object [27].

The communication between interaction devices (mobile devices) and interaction resources (digitalized objects) is the following: The RFID tag (embedded in the object) is a small chip integrated circuit, adapted to a radio frequency antenna that enables communication via ra‐ dio. The energy to generate communication is received from the reader´s radio waves (inte‐ grated into the mobile devices).

Web Services are a set of protocols and standards used to exchange data between applica‐ tions in order to offer services. They facilitate interoperability and enable automated services to be offered, automatically causing the generation of user interfaces, thus allowing user consistency and transparency in use of the technology. Web services are of great importance in the trend of distributed computing on the Internet. To broaden and clarify the concept of Web services, we can quote a presentation by Dr. Marcos Escobar: "A Web Service is a soft‐ ware component that communicates with other applications by coding the XML message and sends this message via standard Internet protocols such as HTTP (Hypertext Transfer Protocol)". Intuitively, a Web Service is similar to a Web site that has a user interface that provides a service to applications, by receiving requests through a message formatted in XML (Extensible Markup Language) from an application, it then performs a task and sends a response message, which is also formatted in XML. The standard protocol for messages is SOAP (Simple Object Access Protocol). A SOAP message is similar to a letter: it is an enve‐ lope containing a header with the address of the recipient, a set of delivery options (data en‐ cryption), and a body with the information or data of the message. The performance of the web services is as follows: the client application sends an XML message to the server, and then the services contained provide an XML document called WSDL (Web Services Descrip‐ tion Language). Its aim is to describe in detail the interfaces so that the user can communi‐ cate with the service. XML Web services are registered so that the user can easily find them. This is performed using UDDI (Universal Description Discovery and Integration). The re‐ sponse to the customer is another XML message that is capable of generating the user inter‐ face that the device in the client´s side is going to display at that moment. Figure 3 shows

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the communication that takes place between Web services and client applications.

are the following: execute a method, update information.

**•** Updating the database and results internally in the system.

include:

Database is an organized collection of data, today typically in digital form. The data is typi‐ cally organized to model relevant aspects of reality. In this case, the database is composed the idtag field. Each idtag is associated with the web service function. Among the functions

The internal operation is as follows: the web service receives the information, which is the output layer, and specifically the id tag which in this application has been read from mobile devices. The system checks the method associated with this id tag in the database. Web Service receives information about the method that it must execute. The execution of this op‐ eration depends on the following parameters: the object identifier, the executed game and the current status in the game. A common flow of actions that a user may perform could

**•** The system automatically generates the corresponding game interface. The projector dis‐

**•** If the answer is right, a message indicates the outcome of play. This user interface con‐ gratulates and encourages the children to continue playing. A few seconds later, the inter‐

plays it. According to the action carried out, different messages might be shown.

face related to the game that is running appears, but at a higher level than before.

The device on the client´s side includes a reader and a controller that is responsible for proc‐ essing information received by the physical object and transforming it into useful informa‐ tion, such as an XML message that is sent to the server, which will process the message and trigger an action, such as the generation of user interfaces or the information requested at that time. The network technology is then used to notify the customer with through web services, connecting the two components: the client and the server (See Figure 4).

**Figure 4.** Communication is based on RFID technology. The mobile device has RFID reader inside. It sends electromag‐ netic waves when a digitalized object is close to mobile device. It processes the information contained in the object and carries out the required action.

#### **3.2. Network layer**

This layer enables the information obtained from the perception layer to be transmitted. This layer is composed by different wireless access technologies such as, Wireless Local Area Networks (WLAMs) (IEEE 802.11 variants), Bluetooth (IEEE 802.15.1). Wireless net‐ works are a good option to establish wireless and mobile communications within the Inter‐ net of Things. We have used Wi-Fi technology because it allows connection of heterogeneous devices with the system (the computer interface that supports games and mobile devices which communicate with the objects). In addition, it allows user mobility, is highly scalable, efficient and lightweight.

#### **3.3. Application layer**

This layer provides services to support the stimulating games. It is consists of a server, which is a computer as part of a network, providing services to the devices which are con‐ nected to it. It provides important functions such as Web Services database.

Web Services are a set of protocols and standards used to exchange data between applica‐ tions in order to offer services. They facilitate interoperability and enable automated services to be offered, automatically causing the generation of user interfaces, thus allowing user consistency and transparency in use of the technology. Web services are of great importance in the trend of distributed computing on the Internet. To broaden and clarify the concept of Web services, we can quote a presentation by Dr. Marcos Escobar: "A Web Service is a soft‐ ware component that communicates with other applications by coding the XML message and sends this message via standard Internet protocols such as HTTP (Hypertext Transfer Protocol)". Intuitively, a Web Service is similar to a Web site that has a user interface that provides a service to applications, by receiving requests through a message formatted in XML (Extensible Markup Language) from an application, it then performs a task and sends a response message, which is also formatted in XML. The standard protocol for messages is SOAP (Simple Object Access Protocol). A SOAP message is similar to a letter: it is an enve‐ lope containing a header with the address of the recipient, a set of delivery options (data en‐ cryption), and a body with the information or data of the message. The performance of the web services is as follows: the client application sends an XML message to the server, and then the services contained provide an XML document called WSDL (Web Services Descrip‐ tion Language). Its aim is to describe in detail the interfaces so that the user can communi‐ cate with the service. XML Web services are registered so that the user can easily find them. This is performed using UDDI (Universal Description Discovery and Integration). The re‐ sponse to the customer is another XML message that is capable of generating the user inter‐ face that the device in the client´s side is going to display at that moment. Figure 3 shows the communication that takes place between Web services and client applications.

Database is an organized collection of data, today typically in digital form. The data is typi‐ cally organized to model relevant aspects of reality. In this case, the database is composed the idtag field. Each idtag is associated with the web service function. Among the functions are the following: execute a method, update information.

The internal operation is as follows: the web service receives the information, which is the output layer, and specifically the id tag which in this application has been read from mobile devices. The system checks the method associated with this id tag in the database. Web Service receives information about the method that it must execute. The execution of this op‐ eration depends on the following parameters: the object identifier, the executed game and the current status in the game. A common flow of actions that a user may perform could include:

**•** Updating the database and results internally in the system.

The communication between interaction devices (mobile devices) and interaction resources (digitalized objects) is the following: The RFID tag (embedded in the object) is a small chip integrated circuit, adapted to a radio frequency antenna that enables communication via ra‐ dio. The energy to generate communication is received from the reader´s radio waves (inte‐

The device on the client´s side includes a reader and a controller that is responsible for proc‐ essing information received by the physical object and transforming it into useful informa‐ tion, such as an XML message that is sent to the server, which will process the message and trigger an action, such as the generation of user interfaces or the information requested at that time. The network technology is then used to notify the customer with through web

**Figure 4.** Communication is based on RFID technology. The mobile device has RFID reader inside. It sends electromag‐ netic waves when a digitalized object is close to mobile device. It processes the information contained in the object

This layer enables the information obtained from the perception layer to be transmitted. This layer is composed by different wireless access technologies such as, Wireless Local Area Networks (WLAMs) (IEEE 802.11 variants), Bluetooth (IEEE 802.15.1). Wireless net‐ works are a good option to establish wireless and mobile communications within the Inter‐ net of Things. We have used Wi-Fi technology because it allows connection of heterogeneous devices with the system (the computer interface that supports games and mobile devices which communicate with the objects). In addition, it allows user mobility, is

This layer provides services to support the stimulating games. It is consists of a server, which is a computer as part of a network, providing services to the devices which are con‐

nected to it. It provides important functions such as Web Services database.

services, connecting the two components: the client and the server (See Figure 4).

grated into the mobile devices).

332 Radio Frequency Identification from System to Applications

and carries out the required action.

highly scalable, efficient and lightweight.

**3.2. Network layer**

**3.3. Application layer**


**•** If the answer is wrong, a message indicates the outcome of the play. This user interface motivates and encourages them to try again. The next user interface is related to the game that is running at the time, but at the same level as before. Voices and motivating messag‐ es sound in every interface to make the user feel actively accompanied and encouraged.

The package consists of three different types of game, each aimed at stimulating a different

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**•** They are divided into different levels to motivate the child when using the game. If the child fails, s/he loses a life and if the user wins, s/he moves on to the next level. Each level

**•** The information is displayed as text, voice and graphics. In addition, the game can show

**•** The feedback-state messages are motivating for the user who then feels more encouraged

**Figure 5.** The first image shows the Mobile devices interfaces. The next image shows the Physical user interfaces, that is, objects that integrate the RFID inside.The first objects are cards with images from the game, and the last image

**Figure 6.** Main interface of the game designed to stimulate user memory, attention and calculative abilities.

cognitive ability such as memory, calculation, attention and auditory discrimination.

**•** It displays the external information differently, as it is different for every level.

the status and game results when the game ends

**•** The user has the possibility of repeating items.

is more difficult.

to continue playing.

shows the notes and coins used for the game.

**•** The system automatically generates the corresponding mobile user interface. It shows feedback and status of the system according to the action carried out.
