United States Patent - AmiCOUR IPamicourip.com/publications/US6727802.pdfplurality of portable Tags...

United States Patent US006727802B2

(12) (10) Patent N0.: US 6,727,802 B2 Kelly et al. (45) Date of Patent: Apr. 27, 2004

(54) ANTI-TEAR PROTECTION FOR SMART 6,364,208 B1 * 4/2002 Stanford et a1. .......... .. 235/492

CARD TRANSACTIONS

_ _ * cited by examiner (76) Inventors: Guy M. Kelly, 2507 Cammito La PaZ,

La Jolla, CA (US) 92037; Kevin J. Page’ PO‘ BOX 2143’ Del Mar’ CA Primary Examiner—EdWin C. Holloway, III (US) 92014; Don P. Plum, 11176 Bootes St., San Diego, CA (US) 92126; (57) ABSTRACT Joseph V J Ravenis, II, 6041 Ridgemoor Dr., San Diego, CA (US) Afast data transfer collection system using message authen 92120 tication and contactless RF proximity card technology in

_ _ _ _ _ non-contact storage and retrieval applications. The system is

( * ) Nonce: Sub]eCt_tO any dlsclalmeri the term of thls generally comprised of Host computers (application com patent is extended or adJusted under 35 T tradio fre uene (RF) terminals and a U.S.C. 154(b) by 0 days. put“ Systems)’ arge “ q ,, y“ . . ,, ’

plurality of portable Tags ( smart or proximity cards). A Host rovides s eci?c a lication functionalit to a Ta

(21) Appl' NO': 10/289’540 holder? with a high degreepcFf protection from frad/dulent use? (22) Filed: Nov. 5, 2002 A Target provides control of the RF antenna and resolves

(65) Prior Publication Data collisions betWeen multiple Tags in the RF ?eld. A Tag provides reliable, high speed, and Well authenticated secure

Us 2003/0071718 A1 APL 17: 2003 exchanges of data/information With the Host resulting from

Related U-S- Application Data the use of a custom ASIC designtincorporating unique analog and digital circuits, nonvolatile memory, and state

(63) Continuation of application No. 09/627,548, ?led on Jul. 28, logic Each Tag engages in a transaction With the Target in 2000, now Pat. No. 6,480,101, which is a continuation of Which a sequence of message exchanges alloW data to be

1355123323\giéggégzizgs?iiiggoé?gli)%rgg?zi)g?gggg read(Written) from(to) the Tag. These exchanges ~establish No_ 08/825,940’ ?led on APL 1’ 1997’ now Pat No_ 6,010’ the RF communication link, resolve communication colh 074- sions With other Tags, authenticate both parties in the

(60) lgg‘gsional application NO‘ 6O/O14’444’ ?led on Apr‘ 1’ transaction, rapidly and robustly relay information through ' the link, and ensure the integrity and incorruptibility of the

(51) Int. Cl.7 ................................................ .. H04Q 5/22 transaction The system architeeture provides Capabilities t0 (52) US Cl- ~~~~~~~~~~~~~~~~~~ ~~ 340/101; 340/1051; 235/492 ensure the integrity of the data transferred thus eliminating (58) Field Of Search ........................... .. 340/101, 10.51, the major problem of corrupting data on the Card and in the

340/561; 235/492; 707/204 system. The architecture and protocol are designed to alloW

(56) References Cited simple and efficient integration of the transaction product system into data/information processing installations.

U.S. PATENT DOCUMENTS

6,317,755 B1 * 11/2001 Rakers et a1. ............. .. 707/204 1 Claim, 17 Drawing Sheets

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US 6,727,802 B2 1

ANTI-TEAR PROTECTION FOR SMART CARD TRANSACTIONS

RELATED APPLICATIONS

This is a continuation of US. application Ser. No. 09/627, 548, ?led Jul. 28, 2000, issuing as US. Pat. No. 6,480,101, Which is a continuation of US. application Ser. No. 08/933, 725, ?led Sep. 19, 1997, noW issued as US. Pat. No. 6,097,292, Which is a continuation-in-part of US. applica tion Ser. No. 08/825,940, ?led Apr. 1, 1997, noW issued as US. Pat. No. 6,010,074, Which claims the bene?t of US. Provisional Application No. 60/014,444, ?led Apr. 1, 1996.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to data/information col lection systems and methods. More particularly, this inven tion relates to proximity contactless automated data/ information collection systems and methods.

2. Description of Related Art The number and frequency of fee and/or information

based transactions that individuals engage in has increased dramatically over the years. As a result of this increase in transactions, the amount of paper produced and time spent engaging in and processing these transactions has also increased. Proximity card technology has been used effec tively to reduce Waste by eliminating the need for paper or plastic in some transactions and to increase efficiency of these transactions by reducing the time spent engaging in and processing these transactions.

Proximity card technology can be advantageously utiliZed in a Wide variety of applications. One signi?cant application concerns replacing small ticket/cash transactions. WorldWide, approximately 80% (225 billion) of all cash transactions are under $20 US. Proximity cards can be used to replace cash in many of these instances by alloWing individuals to have value deducted from their cards as they make purchases or have value added in return for proper consideration. Other applications include, but are not limited to, use of a card as a driver’s license With all of the relevant driving history stored therein, as a passport With stored visa information, as a healthcare card With a complete medical history and insurance information, or as a phone or mass transit card With a prepaid value that is deducted from the card With the use of services. Indeed, proximity card tech nology can be used With any transaction that involves the exchange of data/information betWeen individuals and an institution.

Proximity card technology has already been used effec tively in mass-transit systems. Cubic Corporation, the cur rent assignee of this patent application, developed such a system as is disclosed in International Application Number PCT/US92/08892, titled “Non-Contact Automatic Fare Col lection System,” ?led Oct. 19, 1992, and published May 13, 1993, as WO 93/09516.

In this system, the proximity card retains a fare value representative of funds available for use by its holder. Value is automatically debited from the proximity card in accor dance With the applicable transit fare schedules or credited in exchange for proper consideration. Waste is reduced through the elimination of paper and plastic disposable fare tickets. System throughput ef?ciency is also enhanced by the increased transaction speed. A typical proximity card trans action takes place roughly seven times faster than the time it takes to pass a paper ticket through a standard mechanical

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2 transport. Also, a passenger does not need to Waste time ?nding and removing the card from a personal storage area, such as a purse or Wallet, because data is transmitted via a radio frequency (“RF”) ?eld. Thus no physical or even visual contact betWeen the proximity card and Target (reader/Writer device) is required. A demonstration system generally applying the teachings

of the PCT/US92/08892 application is currently operating in the Washington Metro Area Transit Authority (WMATA) mass-transit system for rail service, ground transportation (buses), and parking lots. In the WMATA system currently in use, fare data is transmitted betWeen the stationary GO CARD® system terminal, referred to herein as a Target, and a proximity card, referred to herein as a Tag, via a RF ?eld.

A stationary GO CARD® system terminal consists of a Target and a Host (i.e., controlling computer). The Target includes a modulator/demodulator and an antenna designed to transmit, via an RF ?eld With a carrier frequency of 13.56 MHZ, a message modulated upon the carrier signal. During operation, the Target emits a continuous RF ?eld designed to evoke a response from a Tag entering in the general prox imity of the Target. Once a Tag is brought Within range, the Target’s RF transmission provides poWer to the Tag, and the Target sends a message to Wakeup the Tag. The Tag Wakes up and establishes an authenticated communication channel With the Host through the Target. The Host can then query the Tag for its stored data and Write neW data into the Tag. Upon completion of this transaction, the Tag is put back to sleep (inactive state).

SUMMARY OF THE INVENTION

The invention provides systems and methods for signi? cantly enhancing the overall performance of contactless proximity automated data collection systems, Which include a Tag, a Target, and a Host. In particular, the invention realiZes advantages such as increased transaction speed, ensured data integrity and security, reduced cost, and reduced poWer consumption in a loW pro?le Tag. The Tag is a portable thin card carried by an individual.

The Target is a radio frequency source that provides a communication link betWeen the Tag and a Host controller. One of the many invention features is collision resolution.

In operation, one or more Tags may attempt communication With the Target at the same time. The invention prevents the problem of collisions in communication that occur When tWo Tags enter the RF ?eld at the same time. Every time a Target receives a ?rst response from a Tag, it checks to see if the response is in proper message form. The ?rst response is designed such that the interference of tWo or more Tags Will likely create an improper message form. Upon receiving an improper message form, the Target Will signal the Tags that the message is invalid and the Tags Will back-off to retry at a later time. In the rare instance Where the Target does not detect a collision When one is present, the Host does a second level of collision detection that is virtually guaran teed to prevent tWo or more Tags from having access to the same Target at one time.

Another feature of the invention is an improved Tag architecture that reduces the transaction time betWeen the Tag and Target While providing a cost effective Tag With an ultra slim pro?le and loW poWer requirements. For example, the invention can facilitate complete secure transit transac tions in approximately 50 milliseconds (ms), Which is approximately 20% of the transaction time generally required by conventional contactless proximity automated data collection systems.

US 6,727,802 B2 3

In particular, the invention utilizes serial data?oW tech niques and variable speed clocking for the Tag. For example, the invention uses serial, rather than parallel, methods to move data throughout the Tag to realiZe a signi?cant savings in chip area. In addition, the invention utiliZes a dynamic clocking system for the Tag. A loW speed clock is used to facilitate communication With the Target. HoWever, for transferring and processing data and messages Within the Tag itself, a high speed clock is used.

Moreover, the invention uses one or more Linear Feed back Shift Registers (LFSR) to facilitate Tag functionality. The LFSRs greatly reduce the circuit complexity, thus increasing the speed, ?exibility, and reliability of the Tag.

Another signi?cant invention feature is the enhanced design of the Tag data memory. The invention uses ferro electric random access memory (FRAM) for data storage thus increasing transaction speed, reducing poWer consumption, and increasing data reliability. For example, the invention performs a Write access to a Tag in 1 micro second rather than conventional electrically erasable programmable read only memory (EEPROM) based systems, Which require approximately 10 ms. Furthermore, the FRAM Writing electrical current requirements are con siderably less than those of an EEPROM. Additionally, a FRAM typically Works for more than 100 billion read or Write cycles compared to approximately 1 million in an EEPROM.

Another invention feature is Tag data buffering techniques for ensured data integrity The data memory includes a four page buffer (64 byte) for the incoming data. Only after every page has been veri?ed is the data Written from the buffer to its ?nal destination, thus premature retraction of the Tag from the ?eld Will not result in partially Written messages.

The Tag of the invention also provides enhanced security features. The Tag provides security on tWo levels: message authentication and restricted memory access. Message authentication Will be discussed in detail beloW. Restricted memory access on the Tag ensures that only authoriZed Hosts can read or Write to a given memory location. This is accomplished by using key partitioning. Each block of Tag memory has a pair of keys(read and Write) and a Host can only access a particular block if it sends information about the necessary key With each read or Write message. An additional feature of the invention is its architectural ?ex ibility. For example, error correction and encryption are readily added to embodiments of the invention.

Yet another feature of the invention is the Tag analog poWer protection circuitry. The Tag prevents breakdoWn (inherent in all silicon chip devices) of the fabricated silicon device from ?uctuation in the RF ?eld While permitting the Tag to receive the amplitude modulation signal from the Target. In particular, the invention features a clamp circuit that is fast enough to react to a sWitched RF situation and to the AM signal on the RF carrier. The clamp removes the AM voltage ?uctuation from the recti?ed carrier, hoWever, the clamp control signal contains the AM signal, and the control signal can be used as the AM signal for the ASIC receiver circuit. An additional bene?t of this clamping technique is that

the clamping voltage can be accurately determined and can be set just beloW the ASIC breakdoWn voltage, alloWing the ASIC to be produced With smaller geometry and on loWer breakdoWn processes.

The foregoing, and other features and advantages of the invention, Will be apparent from the folloWing, more par ticular description of the preferred embodiments of the invention, the accompanying draWings, and the appended claims.

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4 BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a high level block diagram of a contactless proximity automated data collection system in accordance With the principles of the invention.

FIG. 2 is a high level block diagram of a Target.

FIG. 3 is a high level block diagram of a Tag.

FIG. 4A illustrates a typical Host-Target message exchange.

FIG. 4B illustrates a typical Target-Tag message exchange.

FIG. 4C illustrates a typical Host-Tag message exchange. FIG. 5A illustrates a single Tag attempting to communi

cate With a Target.

FIG. 5B illustrates tWo or more Tags attempting to communicate With a Target.

FIG. 6A illustrates a collision resolution protocol scenario for the situation depicted by FIG. 5A.

FIG. 6B illustrates a collision resolution protocol scenario for the situation depicted by FIG. 5B.

FIG. 7A illustrates a collision resolution protocol for a Target state machine.

FIG. 7B is a ?oW diagram illustrating a high level control of a Tag.

FIG. 8 is a detailed signal diagram for the interface betWeen a Tag analog subsystem and a Tag digital sub system.

FIG. 9 is a block diagram of a Tag digital subsystem. FIG. 10 illustrates a detailed schematic diagram of a state

address register. FIG. 11 illustrates a very long instruction Word (VLIW). FIG. 12 illustrates a memory map of a data memory.

FIG. 13 is a detailed block diagram of a Tag analog subsystem.

FIG. 14 is a detailed schematic diagram of a Tag analog subsystem.

DETAILED DESCRIPON OF THE PREFERRED EMBODIMENTS

The currently preferred embodiments of the invention are noW described With reference to the ?gures Where like reference numbers indicate like elements. Also in the ?gures, the left most digit of each reference number corre sponds to the ?gure in Which the reference number is ?rst used.

While the invention is described in the context of an electronic fare collection system for rapid transit or toll applications, it Would be apparent to one skilled in the relevant art that the principles of the invention have con siderably broader applicability to other systems in Which contactless proximity information/data/message is exchanged, collected, or otherWise used. The improved Target and Tag of the invention can be used

advantageously in a fare collection system similar to that described in International Application Number PCT/US92/ 08892, titled “Non-Contact Automatic Fare Collection System,” ?led Oct. 19, 1992, WO 93/09516, Which is incorporated herein by reference in its entirety. Thus, only the features of the invention that differ from the system disclosed in WO 93/09516 are described in detail herein. System OvervieW

FIG. 1 is a high level block diagram of a contactless proximity automated data collection system 100 in accor

United States Patent - AmiCOUR IPamicourip.com/publications/US6727802.pdfplurality of portable Tags...

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