Get Textbooks on Google Play. Rent and save from the world's largest eBookstore. Read, highlight, and take notes, across web, tablet, and phone. RFID HANDBOOK FUNDAMENTALS AND APPLICATIONS IN CONTACTLESS SMART CARDS, RADIO FREQUENCY IDENTIFICATION AND NEAR-FIELD COMMUNICATION, THIRD EDITION Klaus Finkenzeller Giesecke & Devrient GmbH, Munich, Germany Translated by Dorte M¨ uller¨ Powerwording.com A John Wiley and Sons, Ltd., Publication.
A method for wireless data transmission, for example for RFID systems, between a base station and a transponder is provided. For wireless data transmission between a base station and a transponder, data are wirelessly and bidirectionally transmitted between the base station and the transponder through a first interface of a first interface type using a first data transmission protocol, and data are wirelessly and bidirectionally transmitted between the base station and the transponder through at least one second interface of a second interface type using a second data transmission protocol. The first data transmission protocol and the second data transmission protocol correspond at least in part. Contactless identification systems, or so-called radio frequency identification (RFID) systems typically have a base station or reader (or reader unit) and a plurality of transponders or remote sensors. The transponders and their transmitting and receiving devices customarily do not have an active transmitter for data transmission to the base station. Such non-active systems are called passive systems if they do not have their own energy supply, and semi-passive systems if they have their own energy supply. Passive transponders take the energy they require for their supply from the electromagnetic field emitted by the base station.
Another distinguishing feature of different interface types is the type of coupling between the respective interfaces of the transponder and base station. In this regard, a distinction is made between what is called inductive or magnetic coupling and what is called far-field coupling, among others. In simplified terms, with inductive or near-field coupling an antenna coil of the base station and an antenna coil of the transponder form a transformer, for which reason this coupling type is also called transformer coupling. In the case of inductive coupling, a maximum separation between the transponder and the base station is limited to the region of a near field of the antennas used. The near field region is primarily determined by the operating frequency of the interface. In general, backscatter coupling is used to transmit data from a transponder to the base station using UHF or microwaves in the far field of the base station. To this end, the base station emits electromagnetic carrier waves, which the transmitting and receiving device in the transponder modulates and reflects appropriately for the data to be transmitted to the base station using a modulation method.
The typical modulation methods for this purpose are amplitude modulation, phase modulation and amplitude shift keying (ASK) subcarrier modulation, in which the frequency or the phase position of a subcarrier is changed; in this regard, refer once again to Finkenzeller, section 3.2.2, “elektromagnetische Backscatter-Kopplung” (Electromagnetic Backscatter Coupling). Data transmission protocols are typically divided into different layers. One example of this is known as the OSI layer model, with seven data transmission protocol layers. The different layers here are referred to as the physical layer (layer 1), the data link layer (layer 2), the network layer (layer 3), the transport layer (layer 4), the session layer (layer 5), the presentation layer (layer 6), and the application layer (layer 7). For a more detailed description of the OSI model, reference is made to the literature identified above. In transponders, the data transmission protocols are interface-specific, or in other words, each interface type is assigned its own, proprietary data transmission protocol. Thus, for instance, a transmission protocol for transponders with a UHF interface with far-field coupling in the frequency range of 860 MHz to 960 MHz is described in the proposed standard ISO/IECCD 18000-6C dated Jan.
For transponders with an HF interface with inductive coupling with a frequency of 13.56 MHz, a transmission protocol is described in ISO standard 14443. In this context, the data transmission protocols differ significantly across all protocol layers. In WO 2005/109328 A1, which corresponds to U.S. Publication No.
3, a transponder for so-called remote keyless applications is described which has an active, unidirectional interface for the UHF frequency range and multiple bidirectional interfaces for the LF frequency range. The UHF interface and the relevant LF interfaces use different, proprietary data transmission protocols. Because of the different data transmission protocols, uniform processing within a shared protocol stack of the data that is received or transmitted is not possible. SUMMARY OF THE INVENTION. In the inventive method for wireless data transmission between a base station and a transponder, data are wirelessly and bidirectionally transmitted between the base station and the transponder through a first interface of a first interface type using a first data transmission protocol. In addition to data transmission through the first interface, data are alternately or simultaneously transmitted wirelessly and bidirectionally between the base station and the transponder through at least one second interface of a second interface type using a second data transmission protocol. The first and second interface types can differ based on the frequency used and/or the coupling type, for example.
To simplify the protocol processing of the data to be transmitted through the various interface types, the first and second data transmission protocols match at least in part, aside from a modulation method which may in some circumstances be identical. In an embodiment, symbols that are to be transmitted can be coded in the same manner for the first data transmission protocol and for the second data transmission protocol. The matching coding can concern the coding of symbols that are transmitted from the base station to the transponder, as well as the coding of symbols that are transmitted from the transponder to the base station.
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Preferred codings are described in the proposed standard ISO/IECCD 18000-6C dated Jan. 7, 2005 in section 6.3.1.2.3 and in section 6.3.1.3.2. This allows for identical processing—with the exception of the modulation and the physical transmission—of signals to be transmitted, for example in a common digital front end. In a further embodiment, data are transmitted in the form of data frames with a header section, which is also referred to as the preamble, and with a middle section and a trailer section.
Transmission of this nature can take place from the base station to the transponder or from the transponder to the base station. Transmission parameters can be set with the aid of the header section, wherein transmission parameter settings for the first interface type effect transmission parameter settings for the second interface type.
Of course, it is also possible for appropriate transmission parameter settings of the second interface type to effect transmission parameter settings of the first interface type. Such data frames are described in, for example, German patent application DE 10138217, which corresponds to U.S. Publication No. 5, which is incorporated herein by reference. Another example of a transmission parameter setting using a preamble is found in the proposed standard ISO/IECCD 18000-6C dated Jan. 7, 2005 in section 6.3.1.2.8.
There, coding parameters are set to a binary “0” or a binary “1” in the preamble or header section. It is possible to convert the transmission parameter settings among the different interface types by means of transformation specifications. In this way, uniform transmission parameter setting for both interfaces of the transponder is possible. The inventive transponder for wireless data transmission with a base station includes a first interface of a first interface type for bidirectional, wireless data transmission with the base station, and at least one second interface of a second interface type for bidirectional, wireless data transmission with the base station. A digital protocol processing unit coupled to the first interface and to the second interface is designed for uniform interface-type-independent processing of the signals received from the first and second interfaces and the signals to be transmitted to said interfaces.
During transmission of data, the interfaces perform modulation with a carrier signal, amplification of the modulated signal, and subsequent transmission through an antenna, within the physical layer. When receiving data, the signals received by the antenna are demodulated by the applicable interface and transmitted to the protocol processing unit, which then does not perform any additional interface-type-dependent processing. Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. BRIEF DESCRIPTION OF THE DRAWINGS. The transponder 20 includes a first interface in the form of an analog front end 21 and an antenna 22 coupled to the analog front end 21. The first interface operates through a far-field coupling in a frequency range from 860 MHz to 960 MHz.
Data transmission between the base station 10 and the transponder 20 takes place through their respective first interfaces using a data transmission protocol in conformity with the proposed standard ISO/IECCD 18000-6C dated Jan. The transponder 20 additionally includes a second interface in the form of another analog front end 23 and an antenna 24 coupled to the analog front end 23. The second interface operates through an inductive coupling in a frequency range of 13.56 MHz. Data transmission between the base station 10 and the transponder 20 takes place through their respective second interfaces physically, i.e. With a frequency, a modulation method, and signal levels, in accordance with the ISO standard 14443. The transponder 20 further includes a digital front end or a digital protocol processing unit 25 coupled to the first interface 21 and 22, and to the second interface 23 and 24.
The digital protocol processing unit 25 is designed to uniformly process in an interface-independent manner the signals received from the first interface or the first analog front end 21, and from the second interface or the second analog front end 23, and the signals to be transmitted to the interfaces. To this end, the digital front end 25 includes digital circuits that are not shown, for instance logic gates, counters, timers, etc. The digital front end 25 serves mainly to process the protocol layers below the application layer. An important simplification of the digital protocol processing unit 25 in comparison to a case in which data transmission protocols entirely specific to the interface type are used is achieved through the means that important parts of the data transmission protocol for the first interface, i.e., a protocol in conformity with the proposed standard ISO/IECCD 18000-6C dated Jan.
7, 2005, are transferred or adapted to the second interface. As part of the protocol adaptation, the operating frequency, signal level, and backscatter-based data transmission of the transponder, for example, can be adapted to the second interface. 2 shows a header section KA of a data frame transmitted by the base station 10 for setting transmission parameters of the first and/or second interface. The preamble or header section KA shown corresponds to the preamble described in the proposed standard ISO/IECCD 18000-6C dated Jan. 7, 2005 in section 6.3.1.2.8.
The header section is followed by a middle section (not shown) and a trailer section with a frame end marker. The middle section is used for transmitting payload data, which are encoded with the aid of the coding information contained in the header section KA. The symbol D 0 is followed by the symbol RTCAL.
The time duration of the symbol RTCAL is set by the base station 10 such that it is equal to the length of the symbol D 0, which is to say a binary “0,” plus a time period corresponding to a pulse-width coding of a binary “1” in the subsequent middle section. The transponder measures the time duration of the symbol RTCAL and divides the measured time period by two.
Subsequent data or symbols transmitted in the middle section by the base station 10 are interpreted as a binary “0” if their time duration is less than the duration of the symbol RTCAL divided by two, and are interpreted as a binary “1” if their time duration is greater than the duration of the symbol RTCAL divided by two. The transponder according to claim 12, wherein the transponder is a passive transponder.
Description This is the third revised edition of the established and trusted RFID Handbook; the most comprehensive introduction to radio frequency identification (RFID) available. This essential new edition contains information on electronic product code (EPC) and the EPC global network, and explains near-field communication (NFC) in depth. It includes revisions on chapters devoted to the physical principles of RFID systems and microprocessors, and supplies up-to-date details on relevant standards and regulations.
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Taking into account critical modern concerns, this handbook provides the latest information on:. the use of RFID in ticketing and electronic passports;. the security of RFID systems, explaining attacks on RFID systems and other security matters, such as transponder emulation and cloning, defence using cryptographic methods, and electronic article surveillance;. frequency ranges and radio licensing regulations. The text explores schematic circuits of simple transponders and readers, and includes new material on active and passive transponders, ISO/IEC 18000 family, ISO/IEC 15691 and 15692. It also describes the technical limits of RFID systems. A unique resource offering a complete overview of the large and varied world of RFID, Klaus Finkenzeller’s volume is useful for end-users of the technology as well as practitioners in auto ID and IT designers of RFID products.
Computer and electronics engineers in security system development, microchip designers, and materials handling specialists benefit from this book, as do automation, industrial and transport engineers. Clear and thorough explanations also make this an excellent introduction to the topic for graduate level students in electronics and industrial engineering design. Klaus Finkenzeller was awarded the Fraunhofer-Smart Card Prize 2008 for the second edition of this publication, which was celebrated for being an outstanding contribution to the smart card field.