RFID TRANSPONDERS WITH MODIFIABLE SETTINGS

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a radio frequency identification (RFID) transponder. Furthermore, the present disclosure relates to a corresponding method of operating an RFID transponder.BACKGROUND

[0002] Nowadays, radio frequency identification (RFID) transponders are widely used, in different areas of industry and commerce and for various purposes. RFID transponders may for example be embodied as so-called RFID tags or RFID cards. It is noted that, in the present disclosure, near field communication (NFC) transponders are regarded as a specific type of RFID transponders. Thus, the principles described herein may also be applied to NFC transponders. RFID transponders may have predefined settings in order to meet, for example, safety regulations in various countries or regions around the world. Such predefined settings may be difficult to change, resulting in a limited functionality that can be offered by RFID transponders of the kind set forth.

[0003] US 5,751,223 describes an electronic identification system e.g. for identifying goods in a retail store, which comprises an interrogator and a number of transponders. Each transponder includes a number of data registers, and a counter for selecting the registers one at a time in sequence. When the transponder receives an interrogation signal from the interrogator, it returns a response signal containing data from the currently selected register. When the transponder receives a switch signal from the interrogator, it steps the counter on to select the next register in the sequence. One of the bits in the selected register may be used as a mode switching bit, for switching the response signal between a normal power level and a reduced power level.

[0004] US 2008 / 106381 A1 describes a method, apparatus, and system for periodically measuring the level of ambient noise found on a radio frequency channel used by a radio frequency identification interrogator to read radio frequency identification tags. The ambient noise is measured after the radio frequency identification interrogator has transmitted a signal. The measured level of ambient noise is then used to dynamically adjust a threshold value used to predict collisions on the channel.

[0005] US 5,450,492 describes an electronic identification system comprising a transmitter for generating an electromagnetic excitation signal, one or more portable transponders for storing variable identification data, and for transmitting an information signal containing the identification data upon entering the field. Transmission of the information signal is independent of the excitation signal in both time and frequency. A radio frequency receiver is provided for receiving the information signal and in response generating output signal representing the variable identification data contained in the information signal.

[0006] US 2003 / 133435 A1 describes that, for transmitting data between a base station and a transponder, information packets modulated onto an electromagnetic carrier wave each include a header section, a middle section, and an end section. The data are encoded in the middle section using information symbols, e.g. representing digital "1s" and "0s". The header section of at least the first packet defines the number and unique identifications of all of the symbols that will be used for encoding the data in the middle section of this and / or subsequent packets.SUMMARY

[0007] In accordance with a first aspect of the present disclosure, a method of operating a communication system comprising a radio frequency identification (RFID) reader and an RFID transponder is conceived, as defined in claim 1.

[0008] In one or more embodiments, the parameter is specific to a predefined country or geographical region.DESCRIPTION OF DRAWINGS

[0009] Embodiments will be described in more detail with reference to the appended drawings, in which: Fig. 1 shows an illustrative embodiment of an RFID transponder; Fig. 2 shows an illustrative embodiment of a method of operating an RFID transponder; Fig. 3 shows an illustrative embodiment of a communication system; Fig. 4 shows another illustrative embodiment of an RFID transponder; Fig. 5 shows an illustrative embodiment of a command transmission; Fig. 6 shows an illustrative embodiment of a transponder settings modification; Fig. 7A shows an illustrative embodiment of a UHF RFID tag settings modification; Fig. 7B shows another illustrative embodiment of a UHF RFID tag settings modification; Fig. 8 shows a further illustrative embodiment of a UHF RFID tag settings modification. DESCRIPTION OF EMBODIMENTS

[0010] Nowadays, radio frequency identification (RFID) transponders are widely used, in different areas of industry and commerce and for various purposes. RFID transponders may for example be embodied as so-called RFID tags or RFID cards. It is noted that, in the present disclosure, near field communication (NFC) transponders are regarded as a specific type of RFID transponders. Thus, the principles described herein may also be applied to NFC transponders. RFID transponders may have predefined settings in order to meet, for example, safety regulations in various countries or regions around the world. Such predefined settings may be difficult to change, resulting in a limited functionality that can be offered by RFID transponders of the kind set forth.

[0011] RFID communication may be based, for example, on inductive coupling, capacitive coupling or radiative coupling. The communication between an RFID reader and an RFID transponder, such as an RFID tag, is often realized by means of load modulation and can be split into a forward link and a return link. More specifically, the RFID reader may transmit commands to the RFID transponder through a forward link, and the RFID transponder may transmit responses to those commands back to the RFID reader through a return link. The RFID transponder contains a modulator, which load modulates a carrier signal. Different types of load modulation exist, for example active load modulation (ALM) and passive load modulation (PLM). The return link may also be referred to as a backscatter signal or more concisely as "backscatter".

[0012] As mentioned above, RFID transponders may have predefined settings which are difficult to change. For instance, all wireless products have to ensure that country-specific regulations are met. Typically this is achieved by a specific country-dependent user configuration, a country-specific hardware configuration, or by limiting the power to a level which fulfills all regulations (i.e., in the USA, UHF regulations allow 3dB - two times - more power). This may result in an overhead in terms of development effort. Furthermore, in order to meet all regulations the performance of the device may be negatively affected, in particular in circumstances in which strict rules do not apply. Furthermore, a user may still be able to change the configuration and thereby violate a regulation. As an example, in RFID systems tags are typically designed to fulfill worldwide requirements (i.e., country regulations as well as reader-specific requirements. This may result in a non-optimal performance as well as an increased customer effect to ensure that all requirements are met.

[0013] Fig. 1 shows an illustrative embodiment of an RFID transponder 100. The RFID transponder 100 includes a receiver 102 and a controller 104. The receiver 102 is configured to receive a command from an external RFID reader (not shown), wherein the command is a first command transmitted by the RFID reader during a communication session and wherein said command comprises at least one parameter indicative of one or more modifiable settings of the RFID transponder 100. Furthermore, the controller 104 is configured to modify the settings of the RFID transponder 100 in accordance with a value of said parameter. In this way, the settings can easily be modified to achieve a trade-off between performance and compliance with various regulations. More specifically, the settings can be modified at the beginning of a communication session between the RFID reader and the RFID transponder. In other words, all responses transmitted by the RFID transponders will be transmitted using the modified settings, until for instance the settings are modified again at the beginning of the next communication session. Since the command is the first command sent by the RFID reader during a communication session, it effectively initiates the communication session and ensures that the correct settings are used during the entire session. Accordingly, in this way, the performance of the RFID transponder may be optimized during the whole communication session.

[0014] In one or more embodiments, the parameter is specific to a predefined country or geographical region. In this way, the compliance with country-specific or region-specific regulations can be ensured. Furthermore, in a practical implementation, the command is a broadcast command. In this way, the RFID transponder can easily be managed by a broadcasting reader. As mentioned above, the broadcast is effectively the first command sent by the RFID reader during a communication session.

[0015] The modifiable settings include hardware settings of the RFID transponder. By modifying hardware settings of the RFID transponder, the compliance with regulations or other requirements (such as technical requirements on the RFID transponders imposed by the reader infrastructure, for example) may be easily ensured. In a practical implementation, the hardware settings include transmitter settings and / or receiver settings. It is noted that the transmitter and receiver of a transponder may also be combined in a single unit referred to as a transceiver. In that case, the hardware settings may include transceiver settings. Furthermore, it is noted that the transmitter settings and / or receiver settings can easily be modified. For instance, the strength of the signal transmitted by the RFID transponder's transmitter can be limited by the controller, to avoid that the signal strength exceeds a prescribed maximum strength. In the context of the present disclosure, the transmitter includes the transistors or devices for enabling communication with the RFID reader, such as the back modulator or the amplifier of the RFID transponder.

[0016] Furthermore, in one or more embodiments, the hardware settings include modulator settings. By modifying the settings of the RFID transponder's modulator, for instance the modulation strength, the compliance with regulations and requirements of the kind set forth may be further facilitated. Furthermore, the hardware settings may include voltage limiter settings and / or charge pump settings. The modification of these settings further facilitates the aforementioned compliance with various regulations and requirements.

[0017] In one or more embodiments, the modifiable settings include settings indicative of an internal state of the RFID transponder. In the context of the present disclosure, modifying settings indicative of the internal state may include changing the configuration of a state machine, for example by applying other states and / or combinations of states. In this way, the operation of the RFID transponder can easily be adapted. Furthermore, in one or more embodiments, the modifiable settings include a frequency bandwidth in which the RFID transponder operates. Country-specific or region-specific regulations often prescribe a frequency bandwidth in which an RFID transponder should operate. Thus, in accordance with the present disclosure, this frequency bandwidth may easily be adjusted in response to receiving a command which carries information about the country or regions in which the RFID transponder should operate. In a practical implementation, the RFID transponder is an RFID tag or an RFID card.

[0018] Fig. 2 shows an illustrative embodiment of a method 200 of operating an RFID transponder. The method 200 comprises the following steps: at 202, receiving, by a receiver comprised in an RFID transponder, a command from an external RFID reader, wherein said command comprises at least one parameter indicative of one or more modifiable settings of the RFID transponder, and at 204, modifying, by a controller comprised in the RFID transponder, the settings of the RFID transponder in accordance with a value of said parameter. As mentioned above, in this way, the settings can easily be modified to achieve a trade-off between performance and compliance with various regulations.

[0019] Fig. 3 shows an illustrative embodiment of a communication system 300. The communication system 300 comprises an RFID transponder 302 of the kind set forth and an RFID reader 304. The RFID reader 304 is configured to transmit a command to the RFID transponder. In accordance with the present disclosure, said command comprises a parameter indicative of one or more modifiable settings of the RFID transponder 302. The RFID transponder 302 comprises a receiver (not shown) configured to receive the command. Furthermore, the RFID transponder 302 comprises a controller (not shown) configured to modify the settings of the RFID transponder 302 in accordance with a value of said parameter.

[0020] Fig. 4 shows another illustrative embodiment of an RFID transponder 400. The RFID transponder 400 comprises a receiver 402, a controller 404, a modulator 406 and a transmitter 408. The receiver 402 is configured to receive a command from an external RFID reader (not shown). The command comprises a parameter indicative of one or more modifiable settings of the RFID transponder 400. The controller 404 is configured to modify the settings of the RFID transponder 400 in accordance with a value of said parameter. For example, in addition to the charge pump settings, which influence the extent to which a voltage derived from a signal received by the receiver 402 is boosted by a charge pump (not shown), the parameter may indicate a maximum modulation strength of the transponder 400, and / or a maximum strength of signals transmitted by the transmitter 408. According to the invention, the charge pump settings define the number of charge pump stages that are used to boost said voltage. The charge pump may be integrated into the receiver 402, in which case the charge pump settings may be regarded as a specific example of modifiable receiver settings. It is noted that the controller 404 may change the modulation strength of the transponder 400 by controlling the transmitter 408. More specifically, the modulator 406 typically generates a modulation pattern, while the transmitter 408 performs signal shaping and level shifting and thus regulates the strength of the transmitted, modulated signal. Similarly, the controller 404 may control the transmitter 408 in such a way that the transmitter 408 does not transmit signals that exceed a predefined maximum signal strength, provided that such a maximum signal strength is directly specified by the parameter. Accordingly, both a specified maximum modulation strength and a specified maximum signal strength may trigger the controller 404 to cause the transmitter 408 to reduce the strength of the transmitted signals.

[0021] Fig. 5 shows an illustrative embodiment of a command transmission 500. A transmitter 502 on the reader side broadcasts a command 506, which is received by a receiver 504 on the transponder side. The transponder may for example be a ultra-high frequency (UHF) RFID transponder. The broadcast command 506 is a first command sent by the transmitter 502 during a communication session, and it includes a settings parameter, i.e. a parameter indicative of one or more modifiable settings of the RFID transponder. The settings parameter may be indicative of country-specific or region-specific settings, or settings specific to a particular type of reader or application. The broadcast command 506 may be a first command in a communication session between the reader and the transponder, according to a predefined communication protocol. It is noted that the first command may be an uncoded command or a coded command. In the context of the present disclosure, coding a command may include encrypting a command or applying a cover code to the command. Furthermore, it is noted that not only the parameter value may differ between various countries, regions, readers or applications, but also the command itself may differ between them. The receiver 504 may decode the command including the settings parameter, or merely extract the settings parameter from the command if the command is uncoded. Subsequently, a controller of the transponder may modify or configure for example the hardware settings, internal state, return link strength, charge pump state and / or another device setting in dependence on the value of the settings parameter. The modified settings may then be retained until the next communication session, for example.

[0022] Fig. 6 shows an illustrative embodiment of a transponder settings modification 600. The settings modification 600 includes sending 602, by a reader, a first command of a communication session with a transponder. The first command includes country information, i.e. a settings parameter which is indicative of country-specific settings of the transponder. Furthermore, the settings modification 600 includes various steps 604 performed by the transponder. These steps 604 include receiving the command, decoding or extracting the country information, adjusting the internal state and / or transponder behavior (e.g. as influenced by hardware settings of the transponder) according to the received information, and transmitting responses to the reader while applying the modified settings until a next communication session, a next inventory round, a field reset, a change request, or another event occurs.

[0023] Fig. 7A shows an illustrative embodiment of a UHF RFID tag settings modification 700. The settings modification 700 includes sending 702, by a reader, a first command of a communication session with a transponder. The first command includes information that the system operates in the United States of America. Furthermore, the settings modification 700 includes various steps 704 performed by the transponder. These steps 704 include receiving the command, decoding or extracting the country information, adjusting the backscatter strength and the voltage limiter strength to fulfill USA-specific limitations, and transmitting responses to the reader while applying the modified settings until a next communication session, a next inventory round, a field reset, a change request, or another event occurs.

[0024] Fig. 7B shows another illustrative embodiment of a UHF RFID tag settings modification 706. The settings modification 706 includes sending 708, by a reader, a first command of a communication session with a transponder. The first command includes information that the system operates in the European Union. Furthermore, the settings modification 706 includes various steps 710 performed by the transponder. These steps 710 include receiving the command, decoding or extracting the country information, adjusting backscatter strength (i.e., reducing the strength) to fulfill EU-specific limitations, and transmitting responses to the reader while applying the modified setting until a next communication session, a next inventory round, a field reset, a change request, or another event occurs.

[0025] Fig. 8 shows a further illustrative embodiment of a UHF RFID tag settings modification 800. The settings modification 800 includes sending 802, by a reader, a first command of a communication session with a transponder. The first command includes information about the reader (e.g., technical specifications) or a country-specific frequency bandwidth. Furthermore, the settings modification 800 includes various steps 804 performed by the transponder. These steps 804 include receiving the command, decoding or extracting the reader-specific or country-specific information, adjusting or tuning the frequency bandwidth in accordance with said information, and transmitting responses to the reader while applying the modified setting until a next communication session, a next inventory round, a field reset, a change request, or another event occurs.LIST OF REFERENCE SIGNS

[0026] 100RFID transponder 102receiver 104controller 200method of operating an RFID transponder 202receiving, by a receiver comprised in an RFID transponder, a command from an external RFID reader, wherein the command is a first command transmitted by the RFID reader during a communication session and wherein said command comprises at least one parameter indicative of one or more modifiable settings of the RFID transponder 204modifying, by a controller comprised in the RFID transponder, the settings of the RFID transponder in accordance with a value of said parameter 300communication system 302RFID transponder 304RFID reader 400RFID transponder 402receiver 404controller 406modulator 408transmitter 500command transmission 502transmitter (reader side) 504receiver (transponder side) 506broadcast command 600transponder settings modification 602command transmission by a reader 604operations performed by the transponder 700UHF RFID tag settings modification 702command transmission by a UHF RFID reader 704operations performed by the UHF RFID tag 706UHF RFID tag settings modification 708command transmission by a UHF RFID reader 710operations performed by the UHF RFID tag 800UHF RFID tag settings modification 802command transmission by a UHF RFID reader 804operations performed by the UHF RFID tag 504receiver (transponder side) 506broadcast command 600transponder settings modification 602command transmission by a reader 604operations performed by the transponder 700UHF RFID tag settings modification 702command transmission by a UHF RFID reader 704operations performed by the UHF RFID tag 706UHF RFID tag settings modification 708command transmission by a UHF RFID reader 710operations performed by the UHF RFID tag 800UHF RFID tag settings modification 802command transmission by a UHF RFID reader 804operations performed by the UHF RFID tag

Claims

1. A method (200) of operating a communication system comprising a radio frequency identification, RFID, reader and an RFID transponder (100), the method comprising: transmitting, by the RFID reader, a command to the RFID transponder (100), wherein the command is a broadcast command which is a first command in a communication session between the RFID reader and the RFID transponder (100) according to a predefined communication protocol, wherein said command comprises at least one parameter indicative of one or more modifiable settings of the RFID transponder (100), and wherein the modifiable settings include hardware settings of the RFID transponder (100); receiving (202), by a receiver comprised in the RFID transponder, the command; modifying (204), by a controller comprised in the RFID transponder, the settings of the RFID transponder in accordance with a value of said parameter; characterized in that the hardware settings include charge pump settings, wherein said charge pump settings define a number of charge pump stages that are used to boost a voltage derived from a signal received by the RFID transponder.

2. The method (200) of claim 1, wherein the parameter is specific to a predefined country or geographical region.