U.S. patent application number 12/515781 was filed with the patent office on 2010-03-04 for single communication channel between a contactless frontend device and a transceiver device.
This patent application is currently assigned to NXP, B.V.. Invention is credited to Klemens Breitfuss, Markus Harnisch, Reinhard Meindl, Peter Thueringer.
Application Number | 20100056053 12/515781 |
Document ID | / |
Family ID | 39430136 |
Filed Date | 2010-03-04 |
United States Patent
Application |
20100056053 |
Kind Code |
A1 |
Breitfuss; Klemens ; et
al. |
March 4, 2010 |
SINGLE COMMUNICATION CHANNEL BETWEEN A CONTACTLESS FRONTEND DEVICE
AND A TRANSCEIVER DEVICE
Abstract
Method for exchanging data between an NFC device (10) and a
transceiver device (20) via a single communication channel (30),
comprising the steps:--extracting a clock for the data exchange on
the communication channel (30) from an external RF field (50);
and--coding of the data via symbols, wherein the symbols comprise
status information relating to simultaneous accesses of contactless
card functionalities (21, 22, 23) on the transceiver (20) to the
single communication channel (30).
Inventors: |
Breitfuss; Klemens;
(Voitsberg, AT) ; Meindl; Reinhard; (Graz, AT)
; Thueringer; Peter; (Graz, AT) ; Harnisch;
Markus; (Graz, AT) |
Correspondence
Address: |
NXP, B.V.;NXP INTELLECTUAL PROPERTY & LICENSING
M/S41-SJ, 1109 MCKAY DRIVE
SAN JOSE
CA
95131
US
|
Assignee: |
NXP, B.V.
Eindhoven
NL
|
Family ID: |
39430136 |
Appl. No.: |
12/515781 |
Filed: |
November 22, 2007 |
PCT Filed: |
November 22, 2007 |
PCT NO: |
PCT/IB2007/054745 |
371 Date: |
May 21, 2009 |
Current U.S.
Class: |
455/41.2 |
Current CPC
Class: |
G06K 7/10237 20130101;
G06K 19/0723 20130101; H04L 25/45 20130101 |
Class at
Publication: |
455/41.2 |
International
Class: |
H04B 7/00 20060101
H04B007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 23, 2006 |
EP |
06077177.1 |
Claims
1. A method for exchanging data between a contactless frontend
device and a transceiver device via a single communication channel,
comprising the steps: extracting a clock (CLK) for the data
exchange on the single communication channel from an external
RF-field; and coding of the data via symbols, wherein the symbols
comprise status information relating to simultaneous accesses of
contactless card functionalities on the transceiver to the single
communication channel.
2. The method according to claim 1, wherein the data on the single
communication channel are coded via electrical voltages.
3. The method according to claim 2, wherein a framing of the data
on the single communication channel is bit-oriented.
4. Method according to claim 3, wherein the exchange of the data on
the single communication channel is executable in half-duplex.
5 The method according to claim 1, wherein an RF-communication
protocol is executable completely by the transceiver, and wherein a
protocol for the single communication channel is executable by the
contactless frontend device and by the transceiver.
6. The method according to claim 5, wherein the method is
executable for a plurality of the transceivers being connected to
the single communication channel.
7. A single communication channel for an exchange of data between a
contactless frontend device and a transceiver device, wherein the
data are coded via symbols, wherein the symbols comprise status
information relating to simultaneous accesses of contactless card
functionalities on the transceiver device to the single
communication channel.
8. The single communication channel according to claim 7, wherein
the single communication channel is formed as a single wire.
9. The single communication channel according to claim 8, wherein
the data on the single communication channel are coded via
electrical voltages.
10. The single communication channel according to claim 9, wherein
the exchange of the data is executable in half duplex.
11. The single communication channel according to claim 10, wherein
an RF-communication protocol is executable completely by the
transceiver, and wherein a protocol for the single communication
channel is executable by the contactless frontend device and by the
transceiver.
12. The single communication channel according to claim 11, wherein
the method is executable for a plurality of the transceivers being
connected to the single communication channel.
13. An RFID communication system, comprising a contactless frontend
device, a transceiver device and a single communication channel,
wherein the single communication channel is connected both to the
contactless frontend device and to the transceiver device.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a method and a device for
exchanging data between a contactless frontend device and a
transceiver device.
BACKGROUND OF THE INVENTION
[0002] Nowadays, many smart cards according to the standard ISO/IEC
14443 and ISO/IEC 18092 are used. These smart cards can e.g. be
formed as a SIM (Subscriber Identity Module) with integrated mobile
phone functionality. Furthermore, the smart cards can also be
formed as a SAM (Secure Access Module) which is a dedicated
microprocessing unit for authenticating procedures.
[0003] In standard applications, the smart cards are directly
connected with an antenna via analog signal lines. However, for
additional applications of smart cards, particularly when they are
employed in SIM modules, it would also be desirable to directly
connect existing types of smart cards with near field communication
(NFC) devices without the need to provide separate antennas for
both the smart card and the NFC device. In order to connect smart
cards and NFC devices with each other, a communication channel is
foreseen for such purpose.
[0004] From standard ECMA-373 a near field communication wired
interface (NFC-WI) with two wires is known. Furthermore, from ETSI
document SCPt060577 there is known a single wire interface between
a smart card and an NFC frontend device.
OBJECT AND SUMMARY OF THE INVENTION
[0005] It is an object of the invention to provide an improved
single communication channel between a contactless frontend device
and a smart card acting as a secure transceiver device.
[0006] According to the invention there is provided a method for
exchanging data between a contactless frontend device and a
transceiver device via a single communication channel, comprising
the steps: extracting a clock for the data exchange on the
communication channel from an external RF-field, and coding of the
data via symbols, wherein the symbols comprise status information
relating to simultaneous accesses of contactless card
functionalities on the transceiver to the single communication
channel.
[0007] In this way, simultaneous accesses of contactless card
functionalities on the smart card are supported by the inventive
method. Due to the fact that a clock period for an "internal" data
communication between the contactless frontend device and the smart
card is extracted from the external RF field, a well defined
real-time inventory procedure being initiated by the external
reader is thus supported. In a preferred embodiment of the method
according to the invention, a framing of the data on the single
communication channel is bit-oriented. Thus, the method is well
suited to support real time and anticollision requirements of
ISO/IEC 14443 Type A and B, ISO/IEC 18092 or ISO/IEC 15693.
[0008] According to the invention, there is further provided a
single communication channel for an exchange of data between a
contactless frontend device and a transceiver device, wherein the
data are coded via symbols, wherein the symbols comprise status
information relating to simultaneous accesses of contactless card
functionalities on the transceiver device to the single
communication channel. By means of the inventive single
communication channel, advantageously, a multiplicity of
contactless card functionalities can simultaneously access the
single communication channel without disturbing a well defined
information flow between the external reader and a dedicated one
out of the emulated card functionalities.
[0009] The aspects defined above and further aspects of the
invention are apparent from an exemplary embodiment to be described
and explained with reference to this exemplary embodiment
hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The present invention will be explained now in greater
detail with reference to the following figures:
[0011] FIG. 1 shows in principle a block diagram of an RFID
communication system with a contactless frontend device, a
transceiver device and a single communication channel arranged in
between.
[0012] FIG. 2 shows in principle a framing of data and status
information being exchanged on the single communication
channel.
DESCRIPTION OF EMBODIMENTS
[0013] FIG. 1 shows in principle a block diagram of an RFID
communication system 100 with a contactless frontend device 10. The
contactless frontend device 10 can e.g. be formed as a near field
communication (NFC) frontend device being galvanically connected to
a contactless terminal, e.g. an antenna 40. By means of the antenna
40, the RFID communication system 100 is able to communicate with
an external reader (not shown) via an external RF-field 50. Via the
antenna 40 the contactless frontend device 10 supports a wireless
communication being compliant with ISO/IEC 14443 or ISO/IEC 15693
or ISO/IEC 18092. The contactless frontend device 10 is connected
to a smart card 20 (e.g. formed as a SIM card) via a single
communication channel 30. Preferably, the single communication
channel 30 is formed by a single wire. However, in principle it is
also possible that the single communication channel 30 is formed as
a wireless communication channel between the contactless frontend
device 10 and the smart card 20. The smart card 20 acts preferably
as a secure transceiving unit, which means that it sends and
transmits data to the contactless frontend device 10 via the single
commumnication channel 30 in a secure manner with authenticating
functionality. Inside the smart card 20 there are arrangeable and
executeable a muliplicity of secure emulated contactless card
functionalities 21, 22, 23. These functionalities 21, 22, 23 can
e.g. be formed as reader and/or payment and/or authenticating
functionalities. However, though not explicitely shown, also
additional contactless card functionalities are possible to be
arrangeable and executeable on the smart card 20. Furthermore, the
smart card 20 can also be formed as a secure access module (SAM)
with integrated authenticating functionalities.
[0014] A high speed data connection 60 (e.g. via the USB protocol)
is arranged between the smart card 20 and a baseband IC (not shown)
of the RFID communication system 100 and is foreseen to exchange
high speed data between the smart card 20 and the baseband IC. Due
to hardware requirements of said high speed connection 60, an
availability of hardware resources on the smart card 20 for the
connection to the contactless frontend device 10 may be limited.
Therefore, it is desirable to provide an improved single
communication channel between the contactless frontend device 10
and the smart card 20.
[0015] According to the invention, there is foreseen a single
communication channel 30 with improved features over conventional
single communication channels. For example, a handling of a
conventional RF-communication protocol (which handles, amongst
others, a coding and framing of data on the RF field 50, a handling
of synchronization-bits, an amount of data bits inside data frames,
cyclic-redundancy-checks (CRC) and so on) between the external
reader and the transceiver 20 is exclusively and completely handled
by the smart card 20, preferably inside the smart card 20. Hence,
security relevant portions of the RF-communication protocol are
handled inside the smart card 20, thus hampering any harmful
spy-attacks to the RFID communication system 100. In this way, it
is advantageously impossible to decouple a handling of the
inventory procedure between the contactless frontend device 10 and
the smart card 20. An additional protocol according to the
invention handles the data exchange on the single communication
channel 30 and is performed both by the contactless frontend device
10 and the transceicer 20. For the sake of unambiguousness, said
protocol is referenced with CP-protocol ("Common protocol")
hereinafter. The CP-protocol has a transparent behaviour for the
data of the RF-protocol and has two main challenges. Firstly, it
hands over data from the RF-protocol for a data transmission on the
single communication channel 30 in a transparent or mirroring
behaviour. Furthermore, the CP-protocol handles an exchange of
status information between the contactless frontend device 10 and
the smart card 20.
[0016] Preferably, the single communciation channel 30 offers half
duplex performance. Advantageously, said half duplex performance
accommodates requirements of the contactless frontend devide 10 and
reduces hardware complexities. Therefore, it supports a cost-saving
realization of the single communication channel 30. Furthermore,
data on the single communication channel 30 are coded via
electrical voltage levels. To this end, the contactless frontend
device 10 is able to pull an electrical signal level of the single
communication channel 30 up to a logical "HIGH" level. In
equivalence thereto, the smart card 20 is able to pull a signal
condition on the commmunication channel to a logical "LOW" level.
In other words, the logical "HIGH" level is always driven by the
contactless frontend device 10, whereas the logical "LOW" level is
always driven by the smart card 20.
[0017] In more detail, during sending clock/direction information
and/or data to the contactless frontend device 10, the contactless
frontend device 10 drives both the logical "HIGH" and the logical
"LOW" level strong. During reception of data from the smart card
20, the frontend device 10 drives a weak "HIGH" level. In
correspondence thereto, the smart card 20 drives the "LOW" level
strong. Moreover, the "HIGH" level is never driven by the smart
card 20. Thus, advantageously, a multiplicity of card
functionalities 21, 22, 23 on the smart cards 20 can simultaneously
access the single communication channel 30 by maintaining well
defined physical and logical conditions on the single communication
channel 30. Due to the fact that signal conditions on the single
communication channel 30 are represented by electrical voltages,
advantageously, standard digital I/O pads may be used on the smart
card 20 for a galvanical connection to the single communication
channel 30.
[0018] FIG. 2 shows in principle an exemplary implementation of a
data frame FR being transmitted on the single communication channel
30 by means of the CP-protocol. A fundamental time base t.sub.B of
the data frame FR is extracted from the external RF field 50 by the
contactless frontend device 10. To this end, the contactless
frontend device 10 calculates the time base t.sub.B from received
signals from the external reader (not shown) via calculation
algorithms. The time base t.sub.B has preferably a length between
60 nanoseconds and 2400 nanoseconds. Thus, a data rate on the
single communication channel 30 is in accordance with a data rate
on the external RF field 50. Resulting therefrom, advantageously,
any kind of data buffering inside the contactless frontend device
10 or inside the smart card 20 is superfluous, as there is no
difference between the mentioned data rates. Furthermore, a clock
oscillator 25 can be arranged on the smart card 20 and is foreseen
to calculate the data rate from the time base t.sub.B on the single
communication channel 30. For this calculation, technical
requirements to the clock oscillator 25 can be low, so that no
high-qualitative clock oscillators 25 are necessary to be
implemented in the smart card 20.
[0019] A clock period CLK, on which the data transmissison rate
inside the data frame FR is based, has a length of 3.times.t.sub.B
(duty cycle 2/3). The length of the time base t.sub.B is extracted
from the external RF field 50, as mentioned above. Furthermore, the
data frame FR comprises a direction bit DIR, which defines a
direction of a data transmission between the contactless frontend
device 10 and the smart card 20. In a case, that the direction bit
DIR is "LOW", data are transmitted from the contactless frontend
device 10 to the smart card 20. In a case, that the direction bit
DIR is "HIGH", data are transmitted from the smart card 20 to the
contactless frontend device 10. Due to the fact, that the clock CLK
for the single communication channel 30 is extracted from the
external RF field 50, a separate clock oscillator inside the
contactless frontend device 10 is advantageously superfluous.
However, it should be mentioned, that nevertheless any kind of
clock oscillator may be foreseen to be implemented in the
contactless frontend device 10. The date frame FR further comprises
six so called "code units" CU. The code units have a numbering from
1 to 6 (CU1 to CU6). As can be seen from FIG. 2, CU6 operates as a
most significant bit (MSB) and CU1 operates as a least significant
bit (LSB) inside a data portion DATA of the data frame FR. The
direction bit DIR and each of the code units CU1 to CU6 have
preferably a length of 3.times.t.sub.B.
[0020] A meaning of a coding of the code units CU1 to CU6, bits
bit1, bit2, bit3 of the data frame FR and status information which
are all handled by the inventive CP-protocol are illustrated in
more detail with respect to the following table:
TABLE-US-00001 TABLE 1 CU 6 MSB CU 5 CU 4 CU 3 CU 2 CU 1 LSB bit 1
bit 2 bit 3 Symbol bit 1 bit 2 bit 3 11 No data No data No data
Frame = Status Information 10 "0" "0" "0" 01 "1" "1" "1" 00
Collision Collision Collision
Table 1 shows an exemplary mapping of bits (code units,
respectively) inside the data frame FR to digital symbols. As can
be seen, bits inside the data frame FR are named as bit 1, bit 2,
bit 3 and are formed as a combination two code units. A mapping
between the digital symbols and the bits 1, 2 and 3 is as follows:
CU6 is the most significant single bit (MSB), CU1 is the least
significant bit (LSB) inside a data portion DATA of the data frame
FR. CU6 (MSB) and CU5 together form bit 1, CU4 and CU3 together
form bit 2 and CU2 and CU1 (LSB) together form bit 3.
[0021] In case, that for bit 1 the digital symbol "11" is
transmitted on the single communication channel 30, this means that
no data are to be transmitted in the subsequent data frame FR.
Instead, in this case there may be sent numerous status information
which are formed of the bits 2 and 3. For example, an initiation of
a speed change on the single communication channel 30 can be
implemented in this way. Furthermore, also activation/deactivation
or idle commands can be transmitted from the contactless frontend
device 10 to the smart card 20 or vice versa. In this way, a total
amount of 16 different status messages are implementable by the
possible 16 states of a combination of bits 2 and 3.
[0022] Furthermore, in case that for any of the bits 1, 2, or 3 the
digital symbol "10" is assigned, this means a transmission of
digital data "0". Furthermore, in case that to any of the bits 1,
2, or 3 the digital symbol "01" is assigned, this means a
transmission of digital data "1". In a case that the external
reader starts an inventory procedure of the contactless card
functionalities 21, 22, 23 on the smart card 20, at least two or
more of the contactless card funtionalities may respond
simultaneously to the inventory procedure. This results in an
assignment of the digital symbol "00" to any of the bits 1, 2 or 3
and a transmission of this digital symbol on the single
communication channel 30. If any of the bits 1, 2 or 3 shows a
content of digital "00", this fact indicates to the external
reader, that at least two contactless card functionalities on the
smart card 20 had tried to access the single communication channel
30 simultaneously.
[0023] Hence, a state of "collision" is transmitted on the single
communication channel 30. From this information, advantageously,
the external reader may repeat or cancel its inventory procedure,
thus obtaining a timely well defined response behaviour of all of
the inventoried secure emulated contactless card functionalities
21, 22, 23 on the smart card 20. Therefore, by means of the single
communication channel 30 according to the invention, a response
behaviour of numerous contactless card functionalities to an
inventory procedure of an external reader can be well structured.
Summarizing, the method according to the present invention allows
an emulation of more than one contactless card functionality 21,
22, 23 on the smart card 20. Further, also more than a single smart
card 20 may be connected to the single communication channel 30,
thus also allowing an emulation of more than one contactless card
functionality.
[0024] As can be easily seen from FIG. 2 and table 1, the
arrangement of bits to be exchanged on the single communication
channel 30 is bit oriented. Resulting therefrom, together with the
fact that the data rate on the single communication channel 30
matches exactly the data rate in the external RF field 50, the
method according to the invention supports real time- and/or
anticollision requirements of ISO/IEC 14443. Further, the single
communication channel 30 according to the invention provides a
simultaneous transmission of clock, data and control information
between the contactless frontend device 10 and the smart card 20.
This provides the quality that the clock CLK is extracted from the
external RF field 50, thus supporting an avoidance of any kind of
data congestion in the RFID communication system 100. Furthermore,
by use of the invention any conversions between the conventional
RF-protocol and the CP-protocol are superfluous. This saves an
overhead of protocol handling and thus further supports the
fulfilment of the above mentioned real time- and anticollision
requirements. As a result, the external reader, advantageously,
does not realize an existence of the contactless frontend device 10
and is able to perform a "direct" communication procedure with the
smart card 20.
[0025] It should further be observed, that, although the present
invention has been illustrated by an embodiment which is an
implementation according to ISO/IEC 14443 or ISO/IEC 18092 or
ISO/IEC 15693, the present invention is not limited to these
standards, but is also applicable to any RFID communication systems
with comparable timing requirements.
[0026] Finally, it should be noted that the above-mentioned
embodiments illustrate rather than limit the invention, and that
those skilled in the art will be capable of designing many
alternative embodiments without departing from the scope of the
invention as defined by the appended claims. In the claims, any
reference signs placed in parentheses shall not be construed as
limiting the claims. The word "comprising" and "comprises", and the
like, does not exclude the presence of elements or steps other than
those listed in any claim or the specification as a whole. The
singular reference of an element does not exclude the plural
reference of such elements and vice-versa. In a device claim
enumerating several means, several of these means may be embodied
by one and the same item of software or hardware. The mere fact
that certain measures are recited in mutually different dependent
claims does not indicate that a combination of these measures
cannot be used to advantage.
* * * * *