WO2014067547A1

WO2014067547A1 - Nfc controller architecture for emulation of multiple nfc-a devices

Info

Publication number: WO2014067547A1
Application number: PCT/EP2012/071379
Authority: WO
Inventors: Constantine SOCOL; Frederic Goffin; Sorin Adrian BADIU; Amit Jhawar
Original assignee: ST Ericsson SA
Current assignee: ST Ericsson SA
Priority date: 2012-10-29
Filing date: 2012-10-29
Publication date: 2014-05-08
Anticipated expiration: 2015-04-29

Abstract

An object of the present invention is to provide method for simulating several NFC devices based on respective multiple UICCs present in an NFC device. The object is achieved by a method in an NFC controller for transmitting a collision signal. The NFC controller is connectable to an NFC reader. The NFC controller is further connectable to a first UICC, and to a second UICC. The NFC controller obtains(502) a first binary User ID from the first UICC. The NFC controller also obtains(503) at least a second binary User ID, from the second UICC. The collision signal is generated (504) by a logical XOR operation between the first binary User ID and the second binary User ID. The NFC controller transmits the collision signal to the NFC reader, which collision signal indicates that more than one binary User ID has been obtained, resulting in a collision.

Description

NFC Controller Architecture for Emulation of Multiple NFC-A Devices TECHNICAL FIELD

Embodiments herein relates generally to a controller in a near field communication device and a method therein. In particular it relates to generating collisions simulating several NFC Devices.

BACKGROUND

More and more modern electronic devices comprise built in support for Near Field Communications, (NFC). NFC is a technique for communication over very short distances, such as e.g. from zero to about five centimeters. Common applications for NFC are wireless keys and payment services. Other examples may be ticketing payments, access content from smart posters, event information, advertising, business cards exchange, Bluetooth / Wireless LAN connections set-up, car key and car personalized setup / configuration of driver's seat and air-con. A reason for using short distance communication is to avoid tapping from other receivers in the surroundings. The short communications distance also ensures better authentication. Further, there is additional security for example by using dedicated keys and Advanced Encryption Standard, (AES), cryptography for authentication.

For example, a user requires to pay a bill using a mobile phone with NFC support in a store. In this example the store has an NFC Reader. The NFC reader tries to connect to an NFC device in the mobile phone via an air interface. The NFC device comprises a communications interface and an antenna to receive and transmit signals to and from the NFC reader. The signals are forwarded to an NFC controller in the NFC device. The NFC Controller controls all communications with the NFC reader. The NFC controller is connected to one or more Universal Integrated Circuit Cards, (UICC) in the NFC device. The UICCs may be placed in the NFC device in the vicinity of the NFC controller. From a logical point of view, the UICC may comprise the following parts. An operating system which supports the secure execution of NFC applications and secure storage of application data. The operating system may also support secure loading of NFC applications. The UICC also comprises an interface which enables commands and responses to be exchanged with the NFC device. The UICC also comprises an antenna interface which enables the exchange of commands and responses between an NFC application in the UICC and the NFC reader. The UICC also comprises a Secure Element Contactless Management, (SECM) module. The SECM module is responsible for maintaining a list of NFC applications on the secure element, the status of the NFC applications, and data associated with the application. The status of the NFC application indicates whether or not the NFC application is available for selection on the interface of the NFC device. Information associated with the NFC application includes an Application Definition File, (ADF), name, the NFC application lifecycle state and the NFC application priority. The NFC controller may be in different modes. In listen mode the NFC device is in stand by and the NFC controller listens for signals from the NFC reader. The NFC reader constantly transmits a polling command intended to detect and connect to the NFC device. If the polling command is received at the NFC device a response is transmitted with information about the UICC in the NFC device and its available services. When several NFC devices are in front of the NFC reader, the NFC reader will de-select the UICC one by one after going through an anti-collision and selection process. Anti-collision commands are transmitted from the NFC reader to the NFC device. In a next step the UlCCs that do not match for example an expected Application ID, (AID) are de-selected one by one. Finally only one remaining UlCCs will be found if available. The AID is an identification number for an application in the NFC device. In the example above an AID may relate to a credit card such as Visa or MasterCard. In this case Visa and MasterCard each have (has) its own AID respectively. Once a UICC is de-selected, the process is re- started. A new polling and anti-collision sequence is started at the end of which another UICC card will be selected and the NFC reader will check the available AIDs. The NFC reader becomes aware of the presence of multiple UlCCs by collision detection. Finally the UICC is selected with a select command. In another possible scenario, after a selection request command the NFC reader will place, at the end of the anti-collision process the NFC device in a sleep state and will restart the anti-collision process for discovery of all NFC devices present. The NFC devices in sleep state will not take part to the anti-collision any more as they will not reply to polling commands, only to wake-up commands. Both approaches described above are valid and used in various implementations today.

The NFC Controller in the NFC device may be required to perform multiple cards simulation based on multiple UlCCs connected to a SWP interface, with all UlCCs supporting the same NFC technology. The NFC technology that may be

applicable/specific to this patent application is the NFC-A, IS014443A.

A problem with existing solutions is that they are very complex. SUMMARY

An object of embodiments herein is to provide an improved way of handling several UlCCs in the NFC device.

According to a first aspect the object is achieved by a method in a Near-Field

Communication, NFC, controller for transmitting a collision signal. The NFC controller is connectable to an NFC reader, and the NFC controller is further connectable to a first Universal Integrated Circuit Card, and to a second Universal Integrated Circuit Card.

The NFC controller obtains a first binary User ID from the first UICC and also obtains at least a second binary User ID from the second UICC. The collision signal is generated by a logical XOR operation between the first binary User ID and the second binary User ID. The collision signal is transmitted to the NFC reader. The collision signal indicates that more than one binary User ID has been obtained, resulting in the collision.

According to a second aspect the object is achieved by an NFC controller. The NFC 5 controller is adapted to transmit the collision signal. The NFC controller is connectable to a NFC reader and also connectable to a first UICC, and to a second UICC. The NFC controller comprises a first obtaining unit adapted to obtain a first binary User ID, from the first UICC. The NFC controller also comprises a second obtaining unit adapted to obtain at least a second binary User ID, from the second UICC. The NFC controller also 10 comprises a generating unit adapted to generate the collision signal by a logical XOR operation between the first binary User ID and the second binary User ID. Finally the NFC controller comprises a transmitting unit adapted to transmit the collision signal to the NFC reader. The collision signal indicates that more than one binary User ID has been obtained, resulting in a collision.

I5j Since the collision signal is sent, it has been indicated that several NFC devices_^are present. There is no need to send several subsequent responses to the polling signal. This results in an improved way of handling simulation of several NFC devices by one NFC device.

20 The embodiments herein solve the object of the invention in that the NFC reader may handle several NFC devices simulating based on 2 or more UICCs connected to the NFC controller comprised within the NFC device in a less complex way.

An advantage of the embodiments herein is that it is possible to simulate multiple NFC 25 devices with a single NFC controller.

A further advantage of the embodiments herein is that they enable a fast and robust anti- collision and selection mechanism for the best end-user experience.

30 A further advantage of the embodiments herein is that no additional complexity is added to the NFC controller, also avoiding any delays or future changes required by new methods for AID, selection.

A further advantage of the embodiments herein is that the NFC reader will become aware 35 that multiple devices are present in front of the NFC reader starting from the anti-collision phase. If the first selected device is not matching the expected AID or protocol the NFC reader will de-select it but will continue polling without changing the polling technology or switching from polling to listen mode thus parsing all available devices until finding a suitable one until the last one was selected.

40

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of embodiments herein are described in more detail with reference to attached drawings in which:

45 Figure 1 is a schematic block diagram illustrating an NFC reader and an NFC device; Figure 2 is a flowchart depicting embodiments of a method in an NFC controller;

Figure 3 is a schematic block diagram illustrating an NFC controller according to an embodiment;

Figure 4 is a schematic block diagram illustrating an NFC controller according to another embodiment;

Figure 5 is a diagram illustrating different signal levels;

Figure 6 is a schematic block diagram illustrating an NFC controller according to another embodiment; and

Figure 7 illustrates a computer program product being loadable into a memory.

DETAILED DESCRIPTION

As part of the solution according to embodiments herein a problem will first be identified and discussed. A NFC controller in listen mode with UlCCs connected to the SWP interface, will normally send only one reply to a polling command from the NFC reader.

Replies to anti-collision commands will be based on a single User ID, UID, of the UlCC. The NFC reader would remain aware of the presence of only one NFC device in listen mode and may then switch to polling in a different NFC technology or even to the listen mode, not being able to correctly and efficiently parse all NFC devices in the same technology supported by the NFC controller based on all UlCCs.

In some cases when multiple NFC devices are present in front of the NFC reader, replies to a polling command from each NFC device will create collisions making the NFC reader aware of the presence of more than one NFC device. After each anti-collision and selection cycle the NFC reader will de-select the NFC devices one by one if each AID found is not matching the NFC reader targeted AID or if the selected NFC device does not support the desired NFC application.

In the case when several UlCCs are comprised in one NFC device, a single NFC controller simulates multiple NFC devices. In listen mode the NFC reader will restart the polling for selection of another device and the NFC controller may be programmed to use a different protocol or report another AID from its internal list. The NFC reader may change polling technology type and may switch even to listen mode also switching off the communication, as it is aware of only one NFC device present not meeting the expected functionality. Different polling technology types are well known in the NFC standards.

Some current solutions are based on remembering the last UID and AID presented and changing these corresponding to another UlCC for the next polling cycle. These solutions have certain disadvantages. It would be necessary to remember the previous NFC device presented and use different UID and AID on the subsequent polling. For the case of NFC readers that switch off the electromagnetic field, for example when the profile of the NFC device contains polling in other technologies and potentially switching to listen mode it is not deterministic if the next polling takes place in front of the same NFC reader or another NFC reader.

The card emulation device is adapted to send responses by performing load modulation on the same communication interface between subsequent polling sessions for example when the profile of the NFC device contains polling in other NFC technologies and potentially switching to listen mode. It is not random if the next polling takes place in front of the same NFC reader or another NFC reader. Although the configuration of the NFC device in listen mode could change anyway in a round-robin manner, the total time to discover the targeted mode will be much longer at least because the NFC reader may perform polling in other technologies or the NFC device may be even reconfigured in listen mode before the same type of polling will be restarted. Different NFC readers may poll for one or more of different NFC technologies such as NFC-A, NFC-B, NFC-F. In this case the NFC reader should be able to select the right application in NFC-A efficiently. In some cases remembering a configuration implies writing to a non-volatile memory the additional current and the necessary time could be limitations in Power By Field, PBF mode. PBF is a mode where the NFC Controller as well as the UICC is powered by the electromagnetic field between the NFC reader and the NFC device generated by the NFC reader and not using the system's battery as it would be fully discharged but this should not prevent small payments like transport / ticketing or access to continue to work.

Since there is a need to send several responses to the polling signal the prior art solution is very complex.

Embodiments will be exemplified in a non-limiting description.

Figure 1 illustrates a communications network 100 where the embodiments herein may be implemented. The different nodes are related to the nodes in the background, but some of the nodes comprise new functionality according to embodiments in the application. An NFC reader 101 is wirelessly connectable an NFC device 102. The NFC reader 101 may e.g. be comprised at the store for paying a bill. The NFC reader 101 may be a reader in a shop as exemplified in in the background. The NFC device 102 may be comprised in a mobile phone or any other mobile device. The NFC device 102 may be a mobile phone or any other communications device. The NFC device 102 may host multiple NFC applications, including both mobile payment applications and applications related to other service areas. NFC application choice is the process by which a user of the NFC device 102 chooses which NFC applications should be active at a particular time, and the priority associated with the NFC applications. The choice may be done through a user interface on a mobile phone's screen. The NFC reader 101 comprises an NFC reader antenna 103 for communicating with an NFC device antenna 104 comprised in the NFC device 102 over an air interface 105.

The NFC reader antenna 103 and the NFC device antenna 104 are adapted to transmit and receive signal over the air interface 105. How this is performed is well known in the art and is described in the NFC standard. The NFC device antenna 104 is connected to a physical layer 106 of the NFC device 102. The physical layer 106 is adapted to handle the transmission over the air interface 105. The physical layer 106 comprises logic such as mixers, filters and amplifiers to handle this task. How this is performed is well known in the art.

5

The physical layer 106 is connected to an NFC controller 107. The NFC controller 107 is the unit controlling the NFC device 102. The NFC controller 107 enables exchange of commands and responses between an NFC application in an UICC in the NFC device and the NFC reader 101 via the air interface 105. The NFC controller 107 will be further 10 described in more detail below.

The NFC controller 107 is connected to a plurality of UlCCs. Below this will be illustrated with two UlCCs, the first UICC 108, and the second UICC 109. In the embodiments described in this application the number of UlCCs is at least two but may be any natural 15 number N. In figure 1 it is illustrated that the NFC controller 107 is connected to N UlCCs.

The purpose of the embodiments described herein is that the NFC controller 107 generates and transmits a collision signal to the NFC reader 101. The collision signal indicates to the NFC reader 101 that the NFC device 102 comprises several UlCCs 108, 20 109. The advantage of this is that one NFC device may comprise several UlCCs and handle communication with the NFC reader in a less complex way. How the collision signal is generated may be implemented in a variety of ways which will be described below with some examples.

25 Embodiments of a method in the NFC controller 107 for transmitting the collision signal will now be described with reference to a flow chart depicted in figure 2. Figure 2 will be described from the perspective of the NFC controller 107. The NFC controller 107 is connectable to the NFC reader 101. The NFC controller 107 is further connectable to the first UICC 108, and to the second UICC 109.

30

The method comprises the following actions, which actions may be performed in any suitable order. The actions may also be combined.

Action 201

35 In some embodiments the NFC controller 107 may receive polling and anti-collision

commands from the NFC reader 101. These commands may be received via the physical layer 106, and the collision signal may be transmitted via the physical layer 106.

Action 202

40 To be able to generate and transmit the collision signal the NFC controller obtains a first binary User ID, from the first UICC 108. The first binary User ID may be obtained right after the NFC controller 107 is initialized when the NFC device 102 is started before the NFC controller 107 receives a polling command from the NFC reader 101 . The first binary User ID will be further described below.

45 Action 203

The NFC controller also obtains a second binary User ID, from the second UlCC 109. The second binary User ID may be obtained when the NFC controller 107 is initialized before the NFC controller 107 receives a polling command from the NFC reader 101 . The second binary User ID will be further described below.

Action 204

When the first binary User ID and the second binary User ID are obtained, the NFC controller 107 generates the collision signal by a logical XOR operation between the first binary User ID and the second binary User ID. How this is performed in detail will be further explained below.

When the collision signal is generated, collision bits may be generated for the bits where the first binary User ID and the second binary User ID are different. How the different bits are generated will be further described below. Collision bits may only be generated for the bits where the first binary User ID 201 and the second binary User ID 202 are different.

When generating the collision signal, it may be determined when a collision symbol in the collision signal will be generated. How this is determined will be described below.

The collision signal may comprise a collision symbol. The collision has a symbol duration. The collision symbol may be generated for the bits where the first binary user ID (301 ) is different from the second binary user ID (302). When generating the collision signal, the collision symbol is generated with modulation during the symbol duration. This will be described below in relation to figure 5. Action 205

The collision signal is transmitted to the NFC reader 101 . The collision signal indicates that more than one binary User ID has been obtained, resulting in the collision.

In some embodiments the collision signal may be transmitted via the physical layer 106 to the NFC reader 101 .

The transmission of the collision signal may be a response to polling and anti-collision commands.

The generated collision signal is received by NFC reader 101 and the NFC reader 101 determines whether or not there are multiple NFC devices 102 in front of the NFC reader 101 .

Figure 3 illustrates the NFC controller 107 according to an embodiment of the invention. The embodiment comprises the physical layer 106, the first UlCC 108 and second UlCC 109 as described above. The first UlCC 108 comprises the first binary User ID, 301 and the second UlCC 109 comprises the corresponding second binary User ID, 302. The first binary User ID 301 and the second binary User ID 302 are identifiers unique to each UlCC used during the anti-collision process enabling selection of a certain UlCC. According to the embodiment in figure 3, the NFC controller 107 comprises a number of parallel blocks 303-308. Each block is simultaneously and independently handling responses to polling and anti-collision commands from the NFC reader 101 . The number of parallel blocks is the same as the number UICCs. Figure 3 discloses two parallel

5 blocks. Each parallel block comprises a module for communicating with the respective UICC. The communication module uses a Single Wire Protocol, SWP. The modules will be referred to as a first single wire protocol module, 303 and a second single wire protocol module, 304. The first single wire protocol module, 303 enables data exchange with the first UICC 108 over the SWP interface. The second single wire protocol module, 10 304 enables data exchange with the second UICC 109 over the SWP interface.

Each block also comprises a module handling a First In Fist Out, FIFO, queue. These modules are referred to as FIF01 305 and FIF02 306. FIF01 305 is connected to the first single wire protocol module 303 and FIF02 306 is connected to the second single wire 15 protocol module 304. FIF01 305 and FIF02 306 buffer, transmit and receive data

between the NFC reader 101 and the first single wire protocol module 303 and the second single wire protocol module 304.

Each block also comprises one Contactless Tunnelling protocol, CLF module each. The

20 CLF modules in figure 3 are referred to as a first CLF 307 and a second CLF 308. The first CLF is connected to FIF01 305 and second CLF is connected to FIF02 306. The first CLF 307 and the second CLF 308 may be the main blocks ensuring receiving commands and transmitting responses with parity and cyclic redundancy check error checking. The first CLF 307 and the second CLF 308 are also responsible for performing data decoding /

25 encoding, placing received decoded data into FIF01 305 and FIF02 306 to be accessed by software and scheduling responses to received commands with responses. The first CLF 307 and the second CLF 308 may handle in hardware certain parts of the

IS014443A protocol due to the requirements for precise timing for the responses to polling and anti-collision commands using data in dedicated registers prior to the first

30 commands received from the NFC reader 101 . The first CLF 307 and second CLF 308 will follow the anti-collision process and will send responses to anti-collision commands accordingly to the NFC reader 101 . At completion of the anti-collision process the selected UID 301 , 302 will determine a certain CLF block 307, 308 to remain active and provide the response to the last select command from the NFC reader 101. The NFC

35 controller 107 may enter sleep state if a halt or deselect command is received from the NFC reader 101. The CLFs 307, 308 will remain in sleep state until a wake-up command is received allowing subsequent anti-collision cycles.

The NFC controller 107 also comprises a collision generation module 309 connected to 40 the first CLF 307, second CLF 308 and the physical layer 106. The collision generation module 309 generates the collision signal by generating a signal obtained by composition of digital output signals from the first CLF 307 and the second CLF 308. How this is performed in detail will be described together with the description of figure 5 below.

45 Figure 4 illustrates the NFC controller 107 according to another embodiment of the

invention with an implementation based on a single CLF block. This will result in a less complex implementation compared to the implementation in relation to figure 3. The embodiment comprises the physical layer 106 and the first UICC 108 and second

UICC 109 as in figure 1 and 3. The first UICC 108 is connected to a first single wire protocol controller, 401 and second UICC 109 is connected to a second single wire protocol controller, 402. The functionality of the first single wire protocol controller, 401 and the second single wire protocol controller 402 is the same as the first single wire protocol module 303 and second single wire protocol module 304 in fig 3, including the dedicated FIFOs. The first SWP Controller 401 is also connected a first User ID module 403. The second SWP Controller 402 is also connected a second User ID module 404. The first binary User ID 301 , connected to the first UICC 108 may be known to the first User ID module 403 during an initialization phase of the NFC device 102. The second binary User ID 302, connected to the second UICC 109 may be known to the second first binary User ID module 404 during an initialization phase of the NFC device 102. The first binary User ID 301 and second binary User ID 302 are obtained and saved in the NFC controller 107.

The embodiment also comprises a single CLF module 405 having the same functionality as first CLF 307 and second CLF 308 as described in relation to figure 3. The CLF module 405 is the main block ensuring receiving of commands and transmits of responses performing the data decoding and placing extracted data into the local CLF FIFO to be accessed by the software.

The CLF module 405 needs to identify which of the first binary User ID 301 or the second binary User ID 302 is selected in subsequent anti-collision commands. Further commands will be transmitted to the selected UICC. The CLF module 405 will also keep information on the sleep status for each selected NFC device 102 following halt, deselect commands for correctly enabling the responses and collision generation only on wake-up polling commands. When the sleep attribute of a simulated device is set the CLF module 405 will enable a response based on personality only for a wake-up polling command. The CLF module 405 will generate a response with the anti-collision generation based only on the UIDs of personalities which do not have sleep attribute set. The personality of the CLF module 405 is a set of parameters used by the NFC device 102 in answering to the NFC reader 102 polling, anti-collision and select commands defining basic specific functionality and capabilities of the NFC device 102.

A UID collision detection module 406 is connected to the first UID module 403 and the second UID module 404. The UID collision detection module 406 is able to determine positions of where the binary bits in the first binary User ID 301 and second binary User ID 302 will collide, by determining the bits that are different in first binary User ID 301 and second binary User ID 302.

The NFC controller 107 also comprises a collision bits information module 407 connected to the UID collisions detection module 406. The collision bits information module 407 provides control signals to an encoder and collisions generator module 408 to determine when a collision symbol in the collision signal will be generated for collisions simulation.

In the embodiment in figure 4 the encoder and collisions generator module 408 is connected to the CLF module 405, the collision bits information module 407 and the physical layer 106. The encoder and collisions generator module 408 is adapted to generate the collision signal that will be sent to the NFC reader 101 via the physical layer 106. This will be described in detail below. Once the position is identified where the binary bits will collide, the position of the collision bits will be used for generating the collision signal in the encoder and collisions generator module 408 at the time when the responses to anti-collision commands are sent.

Figure 5 describes in detail how the collision signal is generated. In the NFC standard it is defined how logical bit values 501 are modulated. In a logical one, modulation is performed during the first half bit duration. In a logical zero, modulation is performed during the second half bit duration. This is illustrated in figure 5. For logical bits where no collisions occur the ones and zeros are transmitted as usual. For the logical bits where collisions occur the collision signal bit is generated by a logical XOR operation between the first UID 301 and the second UID 302. A dedicated symbol will be generated by the encoder and collisions generator module 408 for collisions simulation. This special symbol is defined with modulation performed during the entire bit duration. In the embodiment of figure 3 this will take place in the collision generation module 309.

Embodiments of the NFC controller 107 for transmitting the collision signal will now be described with reference to block diagram depicted in figure 6.

The NFC controller 107 is adapted to transmit the collision signal. The NFC controller 107 is connectable to the NFC reader 101 and the NFC controller 107 is further connectable to the first UICC 108, and to the second UICC 109.

The NFC controller 107 comprises a first obtaining unit 601. The first obtaining unit 601 is adapted to obtain the first binary User ID 301 , from the first UICC 108. The first obtaining unit 601 may e.g. be the first single wire protocol module 303. The NFC controller 107 further comprises a second obtaining unit 602. The second obtaining unit 602 is adapted to obtain at least a second binary User ID 302, from the second UICC 109 the second single wire protocol module 304.

The NFC controller 107 further comprises a generating unit 603. The generating unit 603 is adapted to generate the collision signal by a logical XOR operation between the first binary User ID 301 and the second binary User ID 302. The generating unit 603 may e.g. be the collision generation module 309 or the encoder and collisions generator module 408. In some embodiments, when generating the collision signal, the generating unit 603 is further adapted to generate collision bits for the bits where the first binary User ID 301 and the second binary User ID 302 are different. The generating unit 603 may further be adapted to determine when a collision symbol in the collision signal will be generated. How this may be determined has been described above.

The collision signal comprise a collision symbol, having a symbol duration. When generating the collision symbols for the bit where the first binary user ID (301 ) is different from the second binary user ID (302) the generating unit 603 is further adapted to generate the collision symbol with modulation during the symbol duration.

The NFC controller 107 further comprises a transmitting unit 604 adapted to transmit the collision signal to the NFC reader 101 . The collision signal indicates that more than one binary User ID 301 , 302 has been obtained, resulting in a collision.

The transmitting unit 604 may further be adapted to transmit the collision signal via the physical layer 106 to the NFC reader 101.

The NFC controller 107 may further comprise a receiving unit 605. The receiving unit 605 is adapted to receive the polling command from the NFC reader 101 . How the polling process works is described above. The transmission of the collision signal is a response to the polling and anti-collision commands.

Figure 7 illustrates a computer program product 701. The computer program product is loadable into a memory 702 of a computerized device. The computerized device comprises software code portions adapted for performing the actions described above. The computerized device may be the NFC controller 107 in the NFC device 102.

The embodiments herein for generating and transmitting a collision signal in the NFC controller 107 may be implemented through one or more processors in the NFC controller 107 or in the NFC device 102, together with computer program code for performing the functions and actions of the embodiments herein. The program code mentioned above may also be provided as a computer program product, for instance in the form of a data carrier carrying computer program code for performing the embodiments herein when being loaded into the electronic device 101 . One such carrier may be in the form of a CD ROM disc. It is however feasible with other data carriers such as a memory stick. The computer program code may furthermore be provided as pure program code on a server and downloaded to the NFC controller 107.

The NFC controller 107 may further comprise an external memory comprising one or more memory units. The external memory is arranged to be used to store data, received data streams, received information, configurations, schedulings, and applications to perform the methods herein when being executed in the NFC controller 107. Those skilled in the art will also appreciate that the modules in the NFC controller 107 as described in relation to figure 3 and 4 above may refer to a combination of analog and digital circuits, and/or one or more processors configured with software and/or firmware, e.g. stored in a memory, that when executed by the one or more processors. One or more of these processors, as well as the other digital hardware, may be included in a single application-specific integrated circuit (ASIC), or several processors and various digital hardware may be distributed among several separate components, whether individually packaged or assembled into a system-on-a-chip (SoC). When using the word "comprise" or "comprising" it shall be interpreted as non-limiting, i.e. meaning "consist at least of".

The embodiments herein are not limited to the above-described preferred embodiments. Various alternatives, modifications and equivalents may be used. Therefore, the embodiments should not be taken as limiting the scope of the invention, which is defined by the appending claims.

Claims

1 . A method in a Near-Field Communication, NFC, controller (107) for transmitting a collision signal, the NFC controller (107) being connectable to an NFC reader (101 ), the NFC controller (107) further being connectable to a first UICC, (108), and to a second UICC (109), the method comprises:

obtaining (202) a first binary User ID (301 ), from the first UICC (108), obtaining (203) at least one second binary User ID (302), from the second UICC (109),

generating (204) the collision signal by a logical XOR operation between the first binary User ID (301 ) and the second binary User ID (302),

transmitting (205) the collision signal to the NFC reader (101 ), which collision signal indicates that more than one binary User ID (301 , 302) has been obtained, resulting in a collision.

The method according to claim 1 further comprising:

receiving (201 ) anti-collision commands from the NFC reader (101 ), and wherein the transmission of the collision signal is a response to the anti-collision commands.

The method according to any of claim 1 -2 wherein generating (204) the collision signal further comprises generating collision bits for the bits where the first binary User ID (301 ) and the second binary User ID (302) are different.

The method according to any of claims 1 -3 where in the collision signal is sent via a physical layer (106) to the NFC reader (101 ).

5. The method according to any of claims 1 -4 wherein generating (204) the collision signal further comprises determine when a collision symbol in the collision signal will be generated.

6. The method according to any of claims 1 -5 wherein the collision signal comprises a collision symbol, having a symbol duration, for the bits where the first binary user ID (301 ) is different from the second binary user ID (302), and wherein generating (204) the collision signal further comprises generating the collision symbol with modulation during the symbol duration.

7. A Near-Field Communication, NFC, controller (107) adapted to transmit a collision signal, the NFC controller (107) being connectable to an NFC reader (101 ), the NFC controller (107) further being connectable to a first UICC, (108), and to a second UICC (109), the NFC controller (107) comprising a first obtaining unit (601 ) adapted to obtain a first binary User ID (301 ), from the first UICC (108),

a second obtaining unit (602) adapted to obtain at least a second binary User ID (302), from the second UICC (109),

a generating unit (603) adapted to generate the collision signal by a logical XOR operation between the first binary User ID (301 ) and the second binary User ID (302), and

a transmitting unit (604) adapted to transmit the collision signal to the NFC reader (101 ), which collision signal indicates that more than one binary User ID (301 , 302) has been obtained, resulting in a collision.

The NFC controller (107) according to claim 7 wherein the NFC controller (107) further comprises:

a receiving unit (605) adapted to receive polling and anti-collision command from the NFC reader (101 ), and wherein the transmission of the collision signal is a response to the polling or anti-collision command.

The NFC controller (107) according to any of claim 7-8 wherein the generating unit (603) adapted to generate the collision signal is further adapted to generate collision bits for the bits where the first binary User ID (301 ) and the second binary User ID (302) are different.

10. The NFC controller (107) according to any of claims 7-9 wherein the transmitting unit (604) is adapted to transmit the collision signal via a physical layer (106) to the NFC reader (101 ).

1 1 . The NFC controller (107) according to any of claims 7-10 wherein the generating unit (603) adapted to generate the collision signal further is adapted to determine when a collision symbol in the collision signal will be generated.

12. The NFC controller (107) according to any of claims 7-1 1 wherein the collision signal comprises a collision symbol, having a symbol duration, for the bits where the first binary user ID (301 ) is different from the second binary user ID (302), and wherein the generating unit (603) adapted to generate the collision signal further is adapted to generate the collision symbol with modulation during the symbol duration.

13. A computer program product (701 ) loadable into a memory (702) of a

computerized device and comprising software code portions adapted for performing one or more actions of claims 1 -6 and/or realizing one or more of the features of claims 7-12.