Patent Grant
7587050
The present invention relates to a method of transmitting signals between at least one base station and a number of mobile data carriers operating in the crypto mode or in the plain mode, wherein
[a] the base station emits at least one command signal and/or data signal that is provided with an identifying pattern,
[b] at least one of the data carriers receives the command signal and/or data signal emitted by the base station that is provided with the identifying pattern,
[c] at least one of the data carriers that receive the command signal and/or data signal transmits to the base station a response signal that is a response to the command signal and/or data signal, and
[d] the base station receives the response signal transmitted by the data carrier (see printed publication EP 1 225 536 A1).
The present invention also relates to a system for transmitting signals, having
The present invention also relates to a base station and to a mobile data carrier for a system of the above-mentioned kind for transmitting signals.
Mobile data carriers of the kind referred to above, which will also be referred to below as “transponders” and which are preferably arranged for the non-contacting exchange or transfer of data with or to the base station, which is also referred to as a “reading unit” or “reader”, are in general use for the purposes of identification and access control, or as data stores on movable items.
Examples of data carriers of this kind are
All the above applications or systems have a base station that exchanges data with the transponders or transfers data to the transponders.
In the case of systems that are equipped with only a single communication or transmission channel, operating for example at an I[ndustry] S[cience] M[edicine] frequency or at a R[adio] F[requency], and that have a base station and a number of mobile data carriers, there may be a plurality of data carriers that are present and/or moving at the same time in the operating zone or reading zone of the base station, i.e. particularly in the latter's signal transmission range; fresh transponders enter the operating zone or reading zone and others leave it to the degree that the transponders in question are moved in space, with for example the pieces of baggage to which they are attached.
To ensure a reliable exchange or transfer of data between the base station and the transponders in systems of this kind, use is made of methods and systems for the transmission of data in which the base station transmits a command signal and/or data signal, such as, for example, a sequence of anti-clash commands, and the transponder responds to this command signal and/or data signal with a response signal (a so-called R[eader] T[alks] F[irst] method or R[eader] T[alks] F[irst] system).
The possibility then exists of encrypting the exchange or transfer of data with or to the chosen, i.e. selected transponders, which means that in many applications the transmission of data can take place not only directly but also in encrypted form. The transmission of the commands and/or data can thus take place in an unencrypted form (=in a non-encrypted or plain-language form or “plain mode”) or in an encrypted form (=in a “crypto mode”), to enable the transponders addressed by the base station to be separated or distinguished.
A problem then arises in that the commands and/or data that are transmitted by the base station in encrypted mode
For this reason, the possibility cannot be ruled out that a command or data segment that is transmitted by the base station in encrypted form to a transponder that is in the crypto mode may, by chance,
For this purpose, there are shown along a time axis that extends horizontally in
With the signals arranged as shown in
In this case, the first (and only) identifying pattern P in
In the representation shown in
In the case shown in
(=response signal A1 in the right-hand part of the second line in
(=response signal A2 in the right-hand part of the third line in
What this means is that the two transponders D1 and D2 each transmit respective data signals A1 and A2 back to the base station B, as is shown in the right-hand part of
So, the conventional set of problems can be summed up as follows:
Because of the fact that the first transponder D1 is using encryption, i.e. is operating in the crypto mode, whereas the second transponder D2 is not doing so, i.e. is operating in the plain mode, the first transponder D1 operating in the crypto mode detects the “right”, because encrypted, command C that was emitted, whereas the second transponder D2 operating in the plain mode interprets the data coming from the base station B as a wrong command K.
This leads to errors in the data because not only does the first transponder D1, which is operating in the crypto mode, rightly and with due authority respond to the original signal from the base station B that was intended for the crypto mode, but so too, wrongly and unexpectedly, does the second transponder D2, which is operating in the plain mode, and the response signal A1 from the first transponder D1 and the response signal A2 from the second transponder D2 are then superimposed on each other.
So, in short, both the transponder D1 that was actually selected and also the transponder D2 that was not selected and, what is more, all the other transponders that are present in and/or moving in the operating zone or reading zone of the base station B at the time, may respond simultaneously. However, a superimposition of the response signals A1, A2 that occurs in this way leads to errors in the data.
What is more, data in the memory of the second transponder D2 may even by destroyed if, for example, the command K that is wrongly interpreted by the second transponder D2 is equivalent or corresponds to a write command, i.e. is identical to a write command.
Taking the disadvantages and shortcomings described above as a point of departure and with due allowance for the prior art outlined above, it is an object of the present invention to further develop a method of the kind detailed in the opening paragraphs and a system, a base station and/or a data carrier of the kinds specified in the opening paragraphs in such a way that the problems reviewed above are avoided in a simple yet effective way, thus ensuring the reliable transmission of data, and hence a reduction in the error rate, in methods and systems employing encrypted transmission of data.
This object is achieved by a method having the features given in claim 1, a system having the features given in claim 4, a base station having the features given in claim 10, and a data carrier having the features given in claim 11. Advantageous embodiments and useful refinements of the present invention are detailed in the characterizing clauses of the respective sets of dependent claims.
Thus, under the teaching of the present invention, at least two different identifying patterns, and in particular start patterns, that can be clearly distinguished from one another are used for the reliable exchange or transfer of data between the base station, which is, for example, in the form of a reading unit or reader, and the data carriers (transponders), thus enabling the particular data carriers (transponders) that are addressed by the base station to be clearly separated or clearly distinguished from one another.
In this way it is ensured that
For this purpose, at least one first identifying pattern is used to identify or mark commands and/or data in the plain mode, whereas at least one second identifying pattern differing from the first identifying pattern identifies or marks all the commands and/or data that are transmitted in the crypto mode.
In a particularly advantageous embodiment of the present invention, the first identifying pattern and/or the second identifying pattern can also be clearly distinguished from the data, for example by way of a least one code violation.
Identifying or start patterns of this kind deliberately cause at least one coding error in the data stream proper, a process that can advantageously be implemented
As has already been stated above, the first start pattern may, in accordance with the invention, be used to identify commands in the standard or plain mode, whereas the second start pattern may identify all the data that is transmitted in the crypto mode.
This is an advantageous way of ruling out the possibility of transponders operating in the plain mode mistakenly interpreting commands or data transmitted in the crypto mode as commands intended for them; the possibility is then equally ruled out of transponders operating in the crypto mode mistakenly interpreting commands or data transmitted in the plain mode as commands intended for them.
If, as above, the (first or second) identifying pattern is also designated the (first or second) start pattern, then it is assumed that this (first or second) pattern will be arranged at the beginning of the signal. In advantageous embodiments of the present invention, the pattern for identifying the encryption may also be situated at the end of the command signal or data signal or at any desired position within the command signal or data signal.
In summary, it can be stated that what is achieved by the method according to the present invention and by a system according to the present invention is reliable transmission of data, and consequently a reduction in the error rate, in methods and systems employing encrypted data transmission to the transponder.
What is also ensured is effective protection for the data held in store in the transponders, because the possibility is ruled out of the transponders that are present and/or moving in the operating zone or reading zone of the base station, i.e. that are present and/or moving in particular within the signal transmission range of the base station, wrongly interpreting the commands or data (segments) coming from the base station; what “wrongly interpreting” means in this connection is that
To allow use to be made of these advantages, the signals that are transmitted by the base station for the selected data carrier or the selected data carriers have assigned to them at least one first identifying pattern or at least one second identifying pattern that differs from the first identifying pattern, by which pattern these signals are marked as having been transmitted by the base station for the said selected data carrier(s), thus enabling the particular data carrier addressed by the base station to be clearly separated or clearly distinguished.
Consequently, a distinction can be made, or a differentiation performed, in a manner essential to the invention,
For this purpose, the given identifying pattern, and in particular the given start pattern, can be individually adjusted, in a manner essential to the invention
This proves to be particularly useful when the system for transmitting data between the base station and the data carriers has only a single communication or transmission channel, in for example what is termed the I[ndustry] S[science] M[edicine] band.
As a supplement to this, it is found to be technically useful that the emission to the base station of, preferably, responding data signals in response to the reception of at least one command signal or data signal having the given identifying pattern can be suppressed in all the data carriers that have not been selected by the base station for the transmission of data, this being done regardless of the rest of the content of the command signal or data signal transmitted by the base station.
The fact of the signals transmitted by the base station for the selected data carrier or data carriers being provided with the identifying or start pattern that is applicable thus produces a variation from an identifying and start pattern that, conventionally, i.e. in the prior art, is single and universal.
What this means is that at least two different identifying or start patterns are used, which are clearly distinguished from one another and by means of which the data carriers, i.e. transponders, are able to distinguish, or differentiate between, the command signals or data signals that are transmitted in different forms; the identifying or start patterns can also be clearly distinguished from the data, by what are termed “code violations”, for example.
Finally, the present invention relates to the use of a method of the kind described above and/or of at least one system of the kind described above for the clash-free transmission of signals
As has already been discussed above, there are various possible ways of embodying and developing the teaching of the present invention in an advantageous manner. In this connection, reference should on the one hand be made to the claims respectively dependent on claim 1 and claim 4 and on the other hand these and other aspects of the invention will be apparent from and will be elucidated with reference to the embodiments described hereinafter with reference to
In the drawings:
Arrangements, elements or features that are the same or similar in
Shown along a time axis that extends horizontally are
Shown in a similar way along a horizontally extending time axis are
As can be seen from the succession of signals that is shown by way of illustration in
For this purpose, the commands or data in the command signals/data signals C and K that are to be emitted by the base station B (=a reading unit or reader, for example) have placed in front of them, in a manner essential to the invention, respectively a first identifying pattern P1 and a second identifying pattern P2, which patterns effect a differentiation by the type, by the character or by the intrinsic nature of the given command signals/data signals C and K. The first identifying pattern P1 and the second identifying pattern P2 differ from one another clearly in respect of their respective start patterns, thus enabling the transponder D1 or D2 that is being addressed by the base station B in the particular case to be clearly separated, i.e. clearly distinguished, by the base station B.
Whereas the first identifying pattern P1 is designed for the encrypted or crypto mode, the second identifying pattern P2 is designed for the unencrypted or plain mode.
This being the case, the first identifying pattern P1 acts as a so-called start pattern to mark the beginning of the command C that is present in encrypted form or of the encrypted data (see
In a similar way to this, the second identifying pattern P2 acts as a so-called start pattern to mark the beginning of the command K that is present in unencrypted form or of the unencrypted data (see
The second identifying pattern P2, which is for example only one bit long, differs from the first identifying pattern P1 in respect of its start pattern. What the first identifying pattern P1 marks in this case is the fact that the encrypted command C that was emitted with the relevant data signal by the base station B applies only to transponder D1, which is operating in the crypto mode; hence what is marked by the second identifying pattern P2 is the fact that the unencrypted command K that was emitted with the relevant data signal by the base station B applies only to transponder D2, which is operating in the plain mode.
The identifying pattern P1 or P2 need not necessarily be positioned at the beginning of the command signal or data signal C or K in this case but may equally well be provided at any desired point within the data transmission or at the end thereof.
It is, however, a criterion for the making of a distinction that encrypted signals C are marked by the first identifying pattern P1 whereas unencrypted signals K are marked by the second identifying pattern P2. On this basis, the two transponders D1, D2 are thus able reliably to detect, by reference to the identifying pattern P1 or P2, whether what is involved is a command signal or data signal C for the first transponder D1 that has been selected or a command signal or data signal K for the second transponder D2 that has been selected.
Due to the variation in the identifying pattern, and in particular start pattern, P1 or P2 in the transmission protocol, there is thus an assurance of smooth, reliable and fault-free exchange or transfer of data between the base station B and the transponders D1, D2, because an encrypted command signal or data signal C from the base station B is always distinguished from an unencrypted command signal or data signal K from the base station B by the respective identifying patterns P1 and P2.
So, if the base station B emits a command signal or data signal C of this kind that is provided with the first identifying or start pattern P1 (see the left-hand half of the first line in
Because the second transponder D2 is in the unencrypted or plain mode, and is thus in the non-selected state, it ignores the command signal or data signal C emitted by the base station B, even though it would wrongly and unexpectedly recognize the content of the encrypted command signal or data signal emitted by the base station B as, say, an unencrypted command signal or data signal K to which it could and even should respond, were the first identifying or start pattern P1, i.e. the first value P1 that the identifying or start pattern assumes, not to suppress any action of this kind.
This ensures that only the first transponder D1, that is intended to respond, does so (=response signal A1 in the right-hand part of the second line in
The base station B is therefore able to receive the data signal A1, i.e. the signal that is transmitted to it as a response by the first transponder D1 that has been selected, without any errors (=right-hand part of the first line in
If on the other hand, in a similar way, the base station B emits an unencrypted command signal or data signal K provided with the second identifying or start pattern P2 (see the left-hand part of the first line in
Because the first transponder D1 is in the encrypted or crypto mode and is thus not in the selected state, it ignores the command signal or data signal K emitted by the base station B, even though it would wrongly and unexpectedly recognize the content of the unencrypted command signal or data signal K emitted by the base station B as, say, an encrypted command signal or data signal C to which it could and even should respond, were the second identifying or start pattern P2, i.e. the second value P2 that the identifying or start pattern assumes, not to suppress any action of this kind.
This ensures that only the second transponder D2, that is intended to respond, does so (=response signal A2 in the right-hand part of the third line in
The base station B is therefore able to receive the data signal A2, i.e. the signal that is transmitted to it as a response by the second transponder D2 that has been selected, without any errors (=right-hand part of the first line in
In a system S (see
In this way, it is ensured
Consequently, by means of different identifying or start patterns P1 and P2, the present invention makes it possible for the error rate to be reduced or errors in the data to be avoided and thus makes possible the reliable transmission of data, and so does in a particularly advantageous way in a system S (see
For this purpose, the signals C and K that the base station B respectively transmits to the data carrier D1 that has been selected and to the data carrier D2 that has been selected have respectively assigned to them, by the method according to the present invention, a first identifying pattern P1 and a second identifying pattern P2 that differs from the first identifying pattern P1, by which patterns the signals C and K can be marked as having been transmitted by the base station B for, respectively, the first data carrier D1 when selected and the second data carrier D2 when selected.
In the data carrier D2 (see
This suppression or non-response is symbolized in
As has already been indicated, the method described above is implemented in a system S as shown in
Associated with this means of transport is a motor-vehicle key by means of which
To allow the electronic immobilizer then to be activated when the locks of the doors of the means of transport are locked, or to allow it to be de-activated when the locks of the doors of the means of transport are unlocked, the motor-vehicle key has the (first) transponder.
The electronic immobilizer is able to be de-activated, on only a single communication or transmission channel (<--> an I[ndustry] S[cience] M[edicine] frequency or a R[adio] F[requency]), by means of this correct data carrier D1 (=transponder in the motor-vehicle key, conforming for example to standard ISO 15693 or to draft standard ISO 18000-2 or ISO 18000-3), but not by means of the data carrier D2 (=another transponder in another motor-vehicle key) that may by chance be transported into the operating zone or reading zone of the base station B.
| Number | Date | Country | Kind |
|---|---|---|---|
| 03101275 | May 2003 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/IB2004/050528 | 4/28/2004 | WO | 00 | 11/4/2005 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2004/100051 | 11/18/2004 | WO | A |
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|---|---|---|---|
| 3706094 | Cole et al. | Dec 1972 | A |
| 4975952 | Mabey et al. | Dec 1990 | A |
| 6211776 | Rohrl et al. | Apr 2001 | B1 |
| 6289105 | Murota | Sep 2001 | B1 |
| 6354500 | Gercekci et al. | Mar 2002 | B1 |
| Number | Date | Country |
|---|---|---|
| 0 805 575 | Nov 1997 | EP |
| 1 225 536 | Jul 2002 | EP |
| Number | Date | Country | |
|---|---|---|---|
| 20070042796 A1 | Feb 2007 | US |
