Automatic real-time highway toll collection from moving vehicles

What is claimed is:

1. An in-vehicle unit for use in an automatic highway toll collection system, said in-vehicle unit comprising:

an rf antenna having a radiation pattern disposed in proximity to an associated vehicle for communicating with a roadside collection station while moving therepast;

rf circuits connected to said antenna for operating in either a first mode wherein a data uplink is established with a roadside collection station by modulating the reflectivity of said antenna or a second mode wherein a data downlink is established with a roadside collection station by demodulating received rf signals;

a smart card controller connected with a smart card; and

a link controller connected to said rf circuits and to said smart card controller and including circuits for causing operation in said first mode to repetitively transmit first data to a roadside collection station and in said second mode to receive second data, based at least in part on said first data, whereupon operation is switched back to said first mode for transmission of third data based at least in part on said second data, said first and third data together collectively comprising an encrypted electronic money transfer.

2. An in-vehicle unit as in claim 1 wherein said smart card contains encrypted data representing monetary value, said smart card and smart card controller being connected to the link controller to provide (a) at least a portion of said first data as part of an encrypted data set representing a transfer of monetary value and (b) at least a portion of said third data based in part on said second data and the remainder of said encrypted data set representing a transfer of monetary value and representing a verified valid debit of a highway toll from the smart card.

3. An in-vehicle unit as in claim 1 wherein said second data includes an encryption of at least some of said first data and is utilized to authenticate the roadside collection station.

4. An in-vehicle unit as in claim 1 wherein said second data includes roadside collection station transaction sequence and roadside collection station lane number data.

5. An in-vehicle unit as in claim 1 wherein at least one of said second and third data includes plural frames of data, each frame including the same roadside collection station transaction sequence and roadside collection station lane number data.

6. An in-vehicle unit as in claim 1 wherein said smart card includes encrypted data representing pre-stored increments of money that are anonymous by failing to include any data capable of revealing person or vehicle identity to the roadside collection station.

7. An in-vehicle unit as in claim 6 wherein said pre-stored encrypted data representing increments of money are untraceable and are communicated from the in-vehicle unit to roadside collection station in an encrypted form that includes data required for its decryption.

8. An in-vehicle unit as in claim 1 wherein said first data includes unique transaction identification data.

9. An in-vehicle unit as in claim 8 wherein said unique transaction identification data includes a portion of toll payment data which otherwise would be transmitted as part of said third data.

10. An in-vehicle unit as in claim 1 wherein the smart card is adapted to provide with standard-speed smart card functions at a first rate when connected to standard smart card interfaces and high-speed smart card functions at a second rate higher than said first rate when connected to an in-vehicle unit.

11. An in-vehicle unit as in claim 1 wherein said in-vehicle unit includes means for optionally operating in a post-payment mode wherein at least one of said first and third data includes billing identity data for a subsequent billing of the toll.

12. An in-vehicle unit as in claim 1 wherein the data processing circuits of said in-vehicle unit include means for processing both closed highway tolls and open highway tolls.

13. An in-vehicle unit as in claim 1 including means for initiating operation in said first mode upon detecting in-vehicle unit proximity to an roadside collection station.

14. A roadside collection station for use in an automatic highway toll collection system, said roadside collection station comprising:

an rf antenna having a radiation pattern disposed in proximity to an associated highway lane at a toll collection zone and for communicating with an in-vehicle moving therepast;

rf circuits connected to said antenna for generating either a first mode wherein a CW rf signal enables an uplink communication of data from a passing in-vehicle unit via modulated reflections of the CW rf signal or a second mode wherein a modulated rf signal provides downlink communication of data to a passing in-vehicle unit; and

a link controller connected to said rf circuits and including means for maintaining said rf circuits in said first mode until first data is successfully received from an in-vehicle unit and thereafter switching to said second mode until second data, based at least in part on said first data, is transmitted to the in-vehicle unit in question whereupon operation is switched back to said first mode for receipt of third data, based at least in part on said second data, said first and third data together collectively comprising an encrypted electronic money transfer.

15. A roadside collection station as in claim 14 further comprising:

cryptographic data processing circuits connected to receive uplink data from said controller and to provide downlink data to said controller, said cryptographic data processing circuits generating at least a portion of said second data from said first data and also authenticating said first and third data as collectively representing a verified valid debit of a highway toll from a smart card containing encrypted data representing monetary value.

16. A roadside collection station as in claim 14 wherein said second data includes at least some of said first data in encrypted form.

17. A roadside collection station as in claim 14 wherein said second data includes roadside collection station transaction sequence and roadside collection station lane number data.

18. A roadside collection station as in claim 14 wherein said second and/or third data includes plural frames of data, each frame including the same roadside collection station transaction sequence and roadside collection station lane number data.

19. A roadside collection station as in claim 17 or 18 including data processing circuits for handling and processing data from and to a plurality of in-vehicle units during the same time internal using said roadside collection station transaction sequence and roadside collection station lane number data to correctly associate together each in-vehicle unit toll collection transaction.

20. A roadside collection station as in claim 14 including a connection to a network of other roadside collection station units associated with nearby highway lanes over which network cross-lane read-in of said third data is passed to the network.

21. A roadside collection station as in claim 14 including a downlink control circuit which prevents operation in said second mode unless authorized by an external downlink controller connected thereto.

22. A roadside collection station as in claim 21 in combination with plural roadside collection stations connected to said external downlink controller which prevents simultaneous downlink communications from roadside collection stations associated with adjacent highway lanes.

23. An automatic highway toll collection system comprising:

a roadside collection station disposed in proximity to at least one respectively corresponding highway lane and having a bi-directional electromagnetic data communication link coupled to a predetermined toll collection zone disposed in proximity to said at least, one respectively corresponding highway lane;

an in-vehicle unit disposed in each of plural vehicles passing along the highway and having a bi-directional electromagnetic data communication link coupled to a predetermined vehicular communication zone that moves with the vehicle and intersects said toll collection zone of the roadside collection station for a limited time period as the vehicle passes along said at least one highway lane;

said in-vehicle units each including a smart card containing encrypted data representing pre-stored increments of money; and

each said roadside collection station and in-vehicle unit including respective data processing circuits connected to its electromagnetic data communication link for effecting at least the following real-time communication and data processing operations during said limited time period:

(a) passing first data from an in-vehicle unit to a roadside collection station to initiate payment of a toll;

(b) calculating toll data at the roadside collection station which is based on said first data and passing from the roadside collection station to the in-vehicle unit second data, including said toll data and unique linkage data linking said second data to said first data; and

(c) debiting the toll from the smart card at the in-vehicle unit and thereafter passing third data from the in-vehicle unit to the roadside collection station including verification data verifying said debiting and unique linkage data linking said third data to said first and second data.

24. An automatic highway toll collection system as in claim 23 wherein said data representing pre-stored increments of electronic money transferred to the roadside collection station are encrypted and yet anonymous by failing to include any data capable of revealing person or vehicle identity to the roadside collection station.

25. An automatic highway toll collection system as in claim 23 wherein said data representing pre-stored increments of electronic money are communicated from the in-vehicle unit to the roadside collection station in a encrypted form that includes data required for its decryption.

26. An automatic highway toll collection system as in claim 23 wherein said first data originating at the in-vehicle unit includes unique transaction identification data.

27. An automatic highway toll collection system as in claim 26 wherein said unique transaction identification data includes a portion of toll payment data, the rest of which is transmitted as part of said third data.

28. An automatic highway toll collection system as in claims 26 or 27 wherein

said unique linkage data, comprising part of the second data, includes a portion of said transaction identification data in encrypted form; and

said in-vehicle unit includes means for locally creating a similar encryption of part of the transaction identification data and for comparing that to the relevant portion of received second data to verify the authenticity of the roadside collection station.

29. An automatic highway toll collection system as in claim 23 wherein said unique linkage data, comprising a portion of the second data and a portion of the third data, includes roadside collection station transaction sequence and roadside collection station lane number data.

30. An automatic highway toll collection system as in claim 29 wherein at least one of said second and third data includes plural frames of data, each frame including said roadside collection station transaction sequence and roadside collection station lane number data.

31. An automatic highway toll collection system as in claim 23 wherein the roadside collection station includes means for communicating with and processing data form and to a plurality of in-vehicle units during a single said limited time period using said unique linkage data to associate together the data related to each in-vehicle unit toll collection transaction.

32. An automatic highway toll collection system as in claim 23 having a plurality of said roadside collection stations, each roadside collection station being disposed in proximity to a respectively associated highway lane at a toll plaza and interconnected to a supervisory plaza computer network to which each roadside collection station forwards received third data not linked to its respectively associated highway lane, said plaza network including means for thereafter verifying the combined parts of a payment.

33. An automatic highway toll collection system as in claim 23 having a plurality of said roadside collection stations, each roadside collection station being disposed in proximity to a respectively associated highway lane and interconnected to a downlink timing controller which allows a given roadside collection station to transmit data to an in-vehicle unit only during downlink time periods authorized by the controller.

34. An automatic highway toll collection system as in claim 33 wherein the downlink timing controller includes means for preventing simultaneous downlink communications from roadside collection stations associated with adjacent highway lanes.

35. An automatic highway toll collection system as in claim 23 wherein each smart card is removably associated with its in-vehicle unit and provides both (a) standard-speed smart card functions at a first rate when connected to standard smart card interface and (b) high-speed smart card functions at a second rate higher than said first rate when connected to an in-vehicle unit.

36. An automatic highway toll collection system as in claim 23 wherein at least some said in-vehicle units include means for optionally operating in a post-payment mode when at least one of said first and third data includes billing identity data for subsequent billing of the toll.

37. An automatic highway toll collection system as in claim 23 or 36 wherein the data processing circuits of each said roadside collection station and in-vehicle unit include means capable of processing both closed highway tolls and open highway tolls.

38. An automatic highway toll collection system as in claim 23 wherein all real-time data processing is performed in the roadside collection station and in-vehicle unit.

39. An automatic highway toll collection system as in claim 23 wherein, during said limited time period;

said roadside collection station initially transmits CW electromagnetic fields into said collection zone awaiting the receipt of said first data from an in-vehicle unit via modulated reflections of said fields; and

said in-vehicle units begin continuously modulating said reflected fields upon detecting entry into said collection zone by detecting the presence of said CW fields thereby continuously transmitting said first data.

40. An in-vehicle unit for use in an automatic highway toll collection system, said in-vehicle unit comprising:

data communication circuits for transmitting first data to a roadside collection station while passing thereby;

crytographic data processing circuits for encrypting at least a portion of said first data with a cryptosystem key also present in an authentic roadside collection station;

data communication circuits for receiving second data from a roadside collection station;

authentication means for comparing at least a portion of said second data with an encrypted portion of said first data to the communicating roadside collection station; and

toll charging means for paying a highway toll as requested by said roadside collection station only if its authenticity has been successfully ascertained.

41. An in-vehicle unit for use in an automatic highway toll collection system having toll account memory means and toll data processor means, said in-vehicle unit having toll account memory means and toll data processor means comprising:

data communications circuits for sending first data to a roadside collection station while passing thereby; thereafter receiving second data from said roadside collection station; and still later sending third data to the roadside collection station;

said third data including plural packets of data; and

said data communications circuits including means for including in each said packet of data predetermined linkage data uniquely linked to said first and second data.

42. An in-vehicle unit for use in an automatic highway toll collection system, said in-vehicle unit comprising:

data communications circuits for transceiving data with a roadside collection station while passing thereby;

a data store of encrypted data representing monetary funds; and

means for sending a portion of the data representing said monetary funds in an initial data communication with a roadside collection station to also serve as a unique toll collection transaction identity code.

43. An in-vehicle unit for use in an automatic highway toll collection system having toll account memory means and toll data processor means, said in-vehicle unit comprising:

data communications circuits for sending first data to a roadside collection station while passing thereby; thereafter receiving second data from said roadside collection station; and still later sending third data to the roadside collection station; and

means for automatically initiating operation of said data communications circuits in a first mode upon detecting an in-vehicle unit passing in proximity to a roadside collection station.

44. A roadside collection station for use in an automatic highway toll collection system having toll account memory means and toll data processor means, said roadside collection station comprising:

data communications circuits adapted for receiving first data from an in-vehicle unit moving therepast; thereafter transmitting second data to said in-vehicle unit; and still later receiving third data from said in-vehicle unit; and

means for encrypting at least a portion of said first data and for including at least some of the result as part of said second data to authenticate the roadside collection station to the in-vehicle unit.

45. A roadside collection station for use in an automatic highway toll collection system having toll account memory means and toll data processor means, said roadside collection station comprising:

data communications circuits for receiving first data from an in-vehicle unit moving therepast; thereafter transmitting second data to said in-vehicle unit; and still later receiving third data from said in-vehicle unit; and

means for including in said second data unique linkage data to said first data and for detecting and using similar unique linkage data in said third data to associate same with the correct in-vehicle unit and first data even in the presence of multiple communicating in-vehicle units within a closely spaced time duration.

46. A roadside collection station for use in an automatic highway toll collection system having toll account memory means and toll data processor means, said road collection station comprising:

data communications circuits for transceiving data with in-vehicle units moving therepast in a multi-lane highway environment; and

said data communications circuits including control means for causing data transmit and receive operations with an in-vehicle unit to occur only when permitted by an external communication timing controller.

Description Submit all comments and votes

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to automatic real-time highway toll collection from moving vehicles. It is especially adapted to the use of an untraceable electronic check debited from a smart card and communicated in a cryptographically sealed envelope with opener. The invention relates directly to an in-vehicle unit (IVU) and a roadside collection station (RCS) and to an overall system incorporating a plurality of RCS's and IVU's The invention may also find use for parking collections and other types of road pricing applications.

2. Related Prior Art

The microwave communication and cryptographic processing components of this invention are related to the following prior issued U.S. Patents which are hereby incorporated herein by reference:

U.S. Pat. No. 4,075,632--Baldwin et al. (1978)

U.S. Pat. No. 4,739,328--Koelle et al (1988)

U.S. Pat. No. 5,030,807--Landt et al (1991)

U.S. Pat. No. 5,055,659--Hendrick et al (1991)

U.S. Pat. No. 4,759,063--Chaum (1988)

U.S. Pat. No. 4,926,480--Chaum (1990)

U.S. Pat. No. 5,131,039--Chaum (1992)

Numerous electronic toll collection systems have been implemented during the past several years. In most cases, vehicle readers and their associated microwave antennas arc located at well defined toll plazas and readable tags are located on the vehicles. As a tag-equipped vehicle enters the read range of the antenna, a fixed code is read out from the tag. The code is then compared with an online database to verify the account and determine vehicle classification. Next, the user's account is debited by the appropriate amount and the vehicle is permitted to pass. This system is simple in the sense that the amount of data to be handled is typically small and data need pass in only one direction (i.e., uplink). These simplifications can lead to a system which may operate with a relatively low data bandwidth and with reasonably high vehicle speeds.

Sometimes the computation of toll charge is based, in part, upon the identity of the entry plaza at which the vehicle entered the system. In this case, it is necessary to either write the identity of the entry plaza into the tag or to communicate the fixed tag code and associated entry plaza over a network so that each exit plaza in the entire system has online access to the data. Needless to say, both of these alternatives complicate the system, necessite a higher bandwidth, and may prove expensive to implement.

Furthermore, some users may object to loss of privacy since the fixed tag code serves to identify the owner and his or her whereabouts. Low value, off-line payment systems which provide privacy to the user are now gaining commercial acceptance. These systems often make use of a reusable smart card or its predecessor, the disposable memory card.

Automatic real-time toll collection in general has been a long-standing goal of many prior efforts The following U.S. Patents are a few examples of prior systems which proport to provide one aspect or another of such systems:

U.S. Pat. No. 4,303,904--Chasek (1991)

U.S. Pat. No. 5,086,389--Hassett et al (1992)

U.S. Pat. No. 5,144,553--Hassett et al (1992)

As explained by Chasek, conventional manual toll collection facilities slow traffic, waste time and fuel and increase air pollution. Such manual facilities can also be relatively inefficient in terms of overhead costs required for toll collection processes.

Chasek is perhaps typical in prior art approaches to automatic toll collection which propose the use of prepaid tolls inserted electronically in the memory of a microwave transponder-data-processor, normally kept in the vehicle. As the vehicle passes through a suitably equipped toll collection facility, a toll plaza microwave transponder receives billing information from the vehicle transponder, calculates the toll, transmits it back to the vehicle transponder where the toll is electronically subtracted from a stored balance. If the resulting balance is not negative, a pass signal is then flashed. Typical information to be stored hi the vehicle transponder permanent memory and communicated to the toll collection facility would include a vehicle-owner identity code, a collection agent code and a vehicle-class code. The availability of this information permits calculation of the toll. A procedure for increasing the pre-paid balance makes possible a computerized and automated double entry bookkeeping and funds transfer system. Security is said to be achieved by "crypto-insertion codes". The stored current electronic money balance in the vehicle transponder is to be indicated by a liquid crystal display.

Such automatic toll systems may offer some improvement over other prior art techniques employing only automatic vehicle identification (e.g. one-way data communication rather than bi-directional data communication) and involving intricate centralized computer facilities for storing and extracting billing information from potentially tens of millions of possible users for each toll transaction. However, there are nevertheless still drawbacks with such conventional approaches to automatic toll paying. For example, in the Chasek system the toll transaction inherently reveals the identity of the vehicle--and therefore inherently reveals the identity of the vehicle owner/driver. This may provide a significant intrusion into the expected privacy of individuals in a society which is presently accustomed to anonymous highway toll payment transactions using untraceable cash/coins or the like.

Furthermore, the Chasek approach requires an initial interrogation by a microwave transponder located at the toll plaza. This implies at least four phases of required bi-directional communication (e.g. the initial interrogating downlink communication, a first uplink communication of vehicle identification, etc., a second downlink communication of the computed toll amount and a second uplink communication indicating a lack of a negative balance in the vehicle transponder. Not only does the described four-phase communication inherently require a considerable time and loss of anonymity to the transaction, it also fails to effectively provide for real-time cryptographically verified debit of the prepaid electronic money balance. Accordingly, such systems are more susceptible to erroneous and/or fraudulent transactions.

Although Chasek refers to security being achieved by "crypto-insertion codes", the only discussion of any cryptography is a brief reference to the determination of a highway entry code from a given vehicle transponder identification code using a "cryptographic sequence". Presumably this would provide some security against fraudulent toll minimization by use of false highway entry data (for "closed" toll highway situations). However, it does not appear to offer any other security against possible fraudulent activity--and it clearly offers no anonymity to the vehicle owners or operators traveling along the highway.

BRIEF SUMMARY OF THE INVENTION

A presently preferred exemplary embodiment of this invention achieves especially efficient bi-directional automatic toll payment communications utilizing anonymous untraceable electronic checks communicated in cryptographically sealed envelopes with openers while utilizing, if desired, as few as three phases of actual data communication for each complete toll transaction (including a fully cryptographically verified debiting of smart card electronic money). Such efficient communication minimizes the time required to complete each toll transaction and thus facilitates use at high vehicle speeds.

In a non-data-communicating preliminary initialization stage, each IVU prepares an initial "commit" data package which already includes a portion of an anonymous cryptographically untraceable electronic check. Due to the very nature of the data in such package, it is extremely likely to be unique insofar all other toll transactions are concerned. Thus it conveniently also serves as a transaction identity code for authenticating and linking subsequent phases of the toll collection transaction. When an IVU comes within the communication "footprint" of an RCS (i.e., the highway area in which reliable communication with an IVU is possible, or in otherwards, the microwave communication zone), this pre-configured "commit" data package is immediately and repetitively transmitted in an up-link mode to the nearest RCS at a toll plaza. When an RCS detects successful receipt of a valid up-link "commit" data package, then it computes a return down-link "challenge" data package (typically including a computed toll amount based, at least in part, upon vehicle classification, highway entrance point, and perhaps other data included in the first up-link data package). This second "challenge" data package also preferably includes a shortened encrypted version of at least some of the first commit data package (e.g., the transaction identity code) so as to authenticate the RCS (i.e. before the IVU effects a cash disbursement to the RCS). The "challenge" data is communicated on a down-link to the appropriate IVU. When an IVU successfully receives an authentic "challenge" data package (i.e., one carrying transaction identity data associated with its own earlier " commit" data package), then an appropriate toll amount is debited from an associated smart card and suitable completion of the untraceable electronic check in that amount (together with the cryptographic opener, linkage data and cryptographically secured verification of a smart card debit) is collected in a third "payment" data package that is communicated on an up-link from the IVU to the RCS, thus completing one entire toll transaction.

Merely increasing communication bandwidth without limit to accommodate more data transmission in less time (e.g., at high vehicle speeds) is typically not practical due to regulatory constraints on utilized bandwidth. Typically only about 10 MHz of bandwidth is provided by regulation for such applications. Thus there is further need for efficient data protocols.

As already briefly mentioned, since the data representing an untraceable electronic check is extremely likely to be unique with respect to all other toll transactions, a portion of that data is advantageously also utilized as transaction identity data communicated in the first "commit" phase of the bi-directional communication process. A shortened encrypted version of this transaction identity data (e.g. encrypted with a secret Data Encryption Standard or "DES" key shared by the IVU and RCS) may then be returned in the "challenge" data so as to authenticate the RCS to the IVU before a toll debit is effected. In addition, to provide further multi-lane functionality, transaction sequence and/or transaction lane data may be generated so as to be unique within a given plaza environment over a time duration longer than any expected toll transaction. This additional transaction identification data may be included in the "challenge" and "payment" phases of each transaction so that a given RCS may appropriately associate different data packets involved in a given transaction and thus simultaneously process toll transactions with a plurality of IVU's. A higher level local area network is also preferably provided between RCS's at a multi-lane facility so that cross-lane data may be redirected at the higher LAN level to the appropriate RCS. Such cryptographically secure transaction linkage data (e.g., the transaction identity data, the transaction sequence data and/or the transaction lane data) is also preferably utilized to provide undeniable proof of toll payment in case the smart card is actually debited by the toll amount but, for some reason, such debiting is not properly recorded by the RCS and, as a consequence, enforcement provisions are subsequently taken against the vehicle in question (e.g. by triggering a photograph of the vehicle license plate).

The preferred exemplary embodiment also utilizes a down-link timing controller so as to coordinate downlink communication on adjacent lanes and avoid potential cross-lane down-link interference by preventing simultaneous downlink communication on adjacent lanes (and/or nearby lanes) of a multilane toll plaza.

If desired, the system may be designed with an ability to handle both "open" and "closed" toll highway configurations. In an open toll highway, a fixed toll may be charged for each vehicle (or vehicle class) at each toll plaza. In a closed highway environment, a particular toll is typically computed as a function of the highway entrance point for a particular vehicle. Such entrance point identity would be communicated through the IVU by an RCS located at the entrance point and then stored so as to become part of the first "commit" phase of communication by the IVU when it next encounters an RCS at some toll plaza along the highway (e.g., possibly at an exit ramp).

The exemplary embodiment of this invention is particularly designed primarily for use in a pre-payment environment (e.g. where there is sufficient pre-paid electronic money in the IVU-associated smart card to pay the requested toll). However, if desired, the same system may also be arranged to handle post-payment scenarios. For example, if a drive realizes that his or her smart card may not contain sufficient remaining electronic money to pay the upcoming toll, then the WU may be conditioned (e.g. via suitable keyboard entry) to revert to an optional post-payment mode wherein vehicle/person identity is transmitted to the RCS. This permits the RCS and associated toll plaza computer to generate a post-payment bill or invoice to the appropriate alternate charging process (e.g. an approved credit card, post-payment billing system, etc.). A PIN code may be required before post-payment is permitted to minimize the chance of a smart card revealing the identity of its owner without the owner's consent.

In the preferred exemplary embodiment, all real time data processing and data communication is done within and between the IVU and RCS. In the exemplary embodiment, art IVU begins the data dialog when it self-triggers itself into an up-link mode of operation as a result of detecting a predetermined threshold of ambient rf level from an RCS. In the preferred exemplary embodiment, modulated backscatter of a continuous wave (CW) microwave signal is used to transmit data in the up-link data direction. Accordingly, each RCS normally operates in a passive uplink mode so as to provide the requisite CW microwave carrier signal enabling an up-link data transmission as soon as an IVU comes within its communication footprint.

To better permit the requisite high speed real time data processing and communication events required for real time automatic toll collection, the smart card utilized in the exemplary embodiment is preferably configured to process data and to communicate in a high speed mode when interfaced with an IVU. However, the stone smart card may revert to standard slower speed processing and data communication at other times such that the electronic money contained in the smart card may be used for other purposes in addition to automatic toll collection.

A bidirectional microwave communication link employing modulated backscatter for short range high speed data communications suitable for use with this invention is known in the prior art. For example, reference is made to the following prior issued U.S. patents, the entire content of each of which is hereby incorporated by reference.

U.S. Pat. No. 4,075,632--Baldwin et al (1978)

U.S. Pat. No. 4,739,328--Koelle et al (1988)

U.S. Pat. No. 5,030,807--Landt et al (1991)

U.S. Pat. No. 5, 055,659--Hendrick et al (1991)

Cryptographic processes for use in generating and communicating anonymous untraceable electronic checks communicated in cryptographically sealed envelopes with openers and suitable for use in the exemplary embodiment of this invention are also known in the prior art. For example, the reader is referred to the following related prior issued U.S. patents, the entire content of each of which is hereby incorporated by reference:

U.S. Pat. No. 4,759,063--Chaum (1988)

U.S. Pat. No. 4,926,480--Chaum (1990)

U.S. Pat. No. 5,131,039--Chaum (1992)

As those in the an will recognize :from the Chaum references, a blind signature system utilizing public key cryptography (e.g. the Rivest Shamir-Adleman or "RSA" cryptosystem) may be used for generating cryptographically secured anonymous untraceable electronic checks which may be communicated, for example, in a cryptographically sealed envelope with opener. Besides anonymity in cash transactions, the use of such public key cryptographic blind signature systems also provides enhanced cryptographic security while yet relaxing the requirements for tamper resistant or tamper proof enclosures for various system components. In particular, as those in the art will appreciate, in a public key cryptosystem, only one key (e.g., the private key) of a public key cryptosystem pair needs to be treated in tamper resistant or tamper proof manner. Accordingly, if one can arrange to use the private key only at a relatively few and secure locations (e.g. at the premises of a bank when a smart card is being filled with electronic money), then one can minimize the need for relatively expensive and complex tamper proof or tamper resistant facilities elsewhere in the cryptosystem. A high speed version may use a secret key shared between a tamper-resistant IVU (SC) and a tamper-resistant RCS.

Instead of a removable smart card, the IVU may itself permanently incorporate a smart card chip (i.e., to be used in lieu of a removable smart card). Such an IVU could be more easily sealed for exterior mounting such as might be required on motorcycles and the like. Such an IVU could also be produced at less cost and in a smaller size. All attributes regarding privacy and security would be preserved.

However, use of such public key cryptography typically suffers the disadvantage of requiting more voluminous data transfers (i.e., larger bandwidth) than for conventional cryptosystems (e.g. as in DES or the like where a single secret key is utilized by both the message sender and the message receiver and where both the message sender and receiver must therefore maintain such secret key and trouper proof or tamper resistant facilities). Accordingly, if more sophisticated public key cryptographic systems are to be utilized in an automatic toll payment system, then it is especially necessary to utilize very efficient data communication protocols and formats so as to ensure that there is ample time available for communicating all of the requisite data within a very short time window (which varies inversely with vehicle speed). The need for me of sophisticated data formatting and protocols becomes especially significant when multi-lane environments are envisioned and/or when multiple simultaneous IVU toll paying transactions are envisioned at multi-lane toll plazas and the like. To accomplish all of these desired goals, extremely high data security and communication efficiency must be simultaneously achieved. This invention provides a particularly secure and efficient way to organize and operate such an automatic real time highway toll collection system.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more completely understood and appreciated by careful study of the following more derailed description of a presently preferred exemplary embodiment of the invention taken in conjunction with the accompanying drawings, of which:

FIG. 1 is a diagrammatic perspective view of a multi-lane toll plaza incorporating an exemplary automatic real time highway toll collection system in accordance with this invention;

FIG. 2 is a block diagram of some major toll collection system components in the exemplary embodiment of FIG. 1;

FIGS. 2A, 2B and 2C depict exemplary operation of a downlink timing controller so as to prevent interference between adjacent lanes in the multi-lane environment of FIG. 1;

FIG. 2D is a simplified block diagram of a possible violation enforcement subsystem for use with the embodiment of FIG. 1;

FIG. 3 is a block diagram of an exemplary in-vehicle (IVU) for use in the embodiment of FIG. 1;

FIGS. 3A and 3B depict an exemplary housing and a possible keyboard/screen user interface for the IVU of FIG. 3;

FIG. 3C is a logic sequence human interface diagram showing an exemplary human interface with the IVU of FIGS. 3, 3A and 3B;

FIG. 3D is a schematic depiction of the link AS