"hands-free" transaction method using a mobile terminal

Abstract

The invention relates to a transaction method that comprises the steps of: sending, by a first communication interface of first and second access points (EB, PB), a request to activate a second communication interface; receiving, by the first interface of the access point (EB, PB), a user identifier (UID), sent by a user terminal (UT1-UT3); determining a distance between the user terminal and the access point, according to transmission times of messages exchanged between the second interface of the access point and the user terminal; when the distance with the first access point is less than a first threshold, obtaining payment data of the user from a remote server (GSRV); and, when the distance with the second access point is less than a second threshold, sending, by a transaction terminal (RT), a request containing the payment data and the transaction data.

Description

[0001] DESCRIPTION

[0002] TITLE: Hands-free transaction process using a mobile terminal

[0003] Technical field

[0004] The present invention relates to the conduct of a payment transaction between a customer having a mobile terminal and a payment terminal. It applies in particular to stores, supermarkets, vending machines for goods, automatic ticket dispensers or ticket dispensers for access to a service such as a transport service, a museum, an amusement park, etc.

[0005] State of the art

[0006] Typically, a payment transaction is made after selecting a list of products and / or services to be purchased, and possibly calculating an amount from the selected list of products and / or services. The customer must then present a payment device such as cash, a bank card, or a mobile terminal ("smartphone") loaded with an electronic wallet application storing bank card data.

[0007] Furthermore, some recent smartphones are equipped with a communication interface compliant with the UWB ("Ultra Wide Band") protocol, in particular to remotely trigger the opening of a door such as a motor vehicle door. This protocol makes it possible to estimate transmission distances with an accuracy of around 10 cm.

[0008] It is desirable to reduce the waiting time of customers queuing at a checkout or ATM. To this end, it is desirable to simplify payment transactions in a store or at an ATM, in particular payment transactions using a bank card in dematerialized form in an electronic wallet. It may also be desirable that such simplification does not affect the security of transactions, and does not increase the risk of bank card data leakage.

[0009] Summary

[0010] Embodiments relate to a transaction method comprising steps consisting of: transmitting, by a first communication interface of a first terminal and by a first communication interface of a second terminal, requests for activation of a second communication interface, of the "Ultra Wide Band" type, the first communication interfaces consuming less energy in a standby state than the second communication interface; receiving, by the first communication interface of a terminal transmitting the activation request among the first and second terminals, an activation response containing a user terminal identifier, transmitted in response to one of the activation requests, by a first communication interface of a user terminal; transmitting a distance measurement request, by the second communication interface of the terminal receiving the activation response;receiving a distance measurement response from the user terminal via the second communication interface of the terminal transmitting the distance measurement request; determining a distance between the user terminal and the terminal receiving the distance measurement response, on the basis of a transmission time of the distance measurement request and / or a transmission time of the distance measurement response; when the terminal receiving the distance measurement response is the first terminal and the distance between the user terminal and the first terminal is less than a first threshold value, transmitting by the first terminal to a remote server a request for identification data relating to the user containing the identifier of the user terminal; receiving from the remote server and storing identification and payment data, in response to the request for identification data;and when the terminal receiving the distance measurement response is the second terminal and the distance between the user terminal and the second terminal is less than a second threshold value, transmitting by a transaction terminal a payment request containing the identification data and transaction data.;

[0011] Thus, the detection of a user terminal by the first terminal makes it possible to acquire identification and payment data of the user in anticipation of and well before conducting a transaction with a payment device determined by the acquired payment data. A transaction can therefore be carried out as soon as the identification and payment data of the user are acquired and without having to present a payment device to a payment terminal. This results in a saving of time and therefore a reduction in the waiting time of customers queuing to pay for their purchases. This time saving is achieved without transmitting sensitive data from the user terminal.Thanks to the accuracy of the distance measurements obtained using the second communication interface, and by assigning a sufficiently low value to the second threshold value, it can be ensured that the user terminal detected at a distance less than this second threshold value is that of the user closest to the transaction site (store checkout or ATM). Furthermore, the implementation of the method does not prevent a conventional transaction from being carried out, for example by presenting a payment device to a payment terminal, in particular in the case where a person is present in front of the checkout without a user terminal being detected at a distance with the second terminal less than the second threshold value.

[0012] According to one embodiment, the method comprises steps of capturing biometric information, calculating a biometric fingerprint from the captured biometric information, and comparing the calculated biometric fingerprint with a biometric fingerprint appearing in the stored identification data, the payment request being issued only if the calculated biometric fingerprint corresponds to a biometric fingerprint appearing in the stored identification data.

[0013] This way, the transaction can be secured without having to present a payment device on a payment terminal.

[0014] According to one embodiment, the user's request for identification and payment data is transmitted to a remote server which transmits in response the identification and payment data corresponding to the user terminal identifier, the identification and payment data being stored locally for a limited period.

[0015] Thus, the user does not need to provide identification and payment data each time he or she makes purchases in a store or at an ATM, and the local storage unit does not need a large capacity to store the identification and payment data corresponding to the detected user terminals. Downloading the identification and payment data corresponding to a user terminal each time it is detected by the first terminal also makes it possible to have the most recent data provided by the user of the terminal.

[0016] According to one embodiment, the method comprises steps of constituting a list of user terminals having transmitted an activation response, each element of the list comprising a user terminal identifier associated with the user's identification and payment data and the distance between the user terminal and the second terminal.

[0017] The creation of such a list makes it possible to have the user's identification and payment data at the time the transaction is to be carried out. This list allows users to present themselves at the checkout in a different order than that in which they are detected by the first terminal. According to one embodiment, the identification data transmitted in the payment request are those of an element of the list associated with the smallest distance.

[0018] According to one embodiment, the list is erased periodically or when all users whose terminal identifiers appear in the list are no longer present near one of the first and second terminals.

[0019] This provision makes it possible to limit the number of user IDs stored, and thus to speed up the search for the identification and payment data of the user present at the checkout.

[0020] According to one embodiment, the first communication interface is of the "Bluetooth Low Energy" or WiFi™ type.

[0021] These communication interfaces have the advantage of consuming little energy. They can therefore remain active on user terminals without significantly affecting the terminals' battery life.

[0022] According to one embodiment, the distance measurement is determined: based on an average value of the transmission time of the distance measurement request and the transmission time of the distance measurement response, or based on the transmission time of the distance measurement request, the transmission time of the distance measurement response, and the transmission time of the activation response transmitted by the user terminal.

[0023] Both types of measurements provide better accuracy than measuring a single transmission time.

[0024] According to one embodiment, when the distances measured by the first terminal are greater than the second threshold value and a transaction must be carried out, the method comprises steps consisting of: acquiring payment data via a bank card reader, and issuing by a transaction terminal a payment request containing the acquired payment data and the transaction data; and / or transmitting to the user an invitation message to provide identification and payment data to the remote server.

[0025] Embodiments may also relate to a system comprising a first terminal, a second terminal, a transaction terminal arranged in proximity to the second terminal, a local server in communication with a remote server, and connected to the transaction terminal and to the first and second terminals, the first and second terminals comprising a first communication interface and a second communication interface of the "Ultra Wide Band" type, the first communication interface consuming less energy in a standby state than the second communication interface, the system being configured to implement the method previously defined, with a user terminal within radio range of one or other of the first and second terminals.

[0026] According to one embodiment, the system comprises a biometric data sensor coupled to the transaction terminal.

[0027] Brief description of the figures

[0028] The present invention will be better understood with the aid of the following description of exemplary embodiments with reference to the appended figures, in which identical reference signs correspond to structurally and / or functionally identical or similar elements.

[0029] Figure 1 schematically represents a store equipped to implement a payment method according to one embodiment,

[0030] Figure 2 schematically represents a terminal installed in the store or a user terminal, according to one embodiment,

[0031] Figure 3 represents steps of a payment method, according to one embodiment,

[0032] Figure 4 represents other steps of the payment method, according to one embodiment,

[0033] Figures 5A and 5B illustrate two modes of calculating distance between two transmitter / receiver devices, which can be used within the framework of the payment method, according to one embodiment.

[0034] Detailed description

[0035] Figure 1 shows a store ST in which at least one entrance terminal EB and one cash register terminal PB, a local server LSRV, and a payment terminal RT are installed. Each of the terminals EB, PB is configured to measure a distance between the terminal and a detected user mobile terminal UT1. The terminal EB can be installed near the entrance ENT of the store or at the entrance to a queue for access to a cash register of the store. The terminal PB is installed near the payment terminal RT. The terminals PB, EB are connected to the local server LSRV. The payment terminal RT is connected to the terminal PB and to the server LSRV. The local server LSRV is configured to connect to a remote server GSRV via a wired network NT such as the Internet network or a wireless network such as a mobile telephone network. Figure 1 also shows other user terminals UT2, UT3 near the payment terminal RT.The ST store may include several checkouts. In this case, it includes several groups of payment terminals and distance measuring terminals, such as the PB, RT group.

[0036] Figure 2 represents a device that can be one of the user terminals UT and each of the two terminals EB, PB. This device comprises in particular a processing unit MP, a first communication interface COM1, for example of the BLE ("Bluetooth Low Energy") or WiFi™ type, and a second communication interface COM2 of the UWB ("Ultra Wide Band") type configured to measure distances on the basis of message propagation times in a link established with another communication interface of the type of the second interface. The communication interfaces of the BLE or WiFi™ type have the advantage of being able to remain active or in standby mode without excessive power consumption, which is not the case for the communication interfaces of the UWB type. The first communication interface therefore consumes less energy in a standby state than the second communication interface.The implementation of the first communication interface therefore makes it possible in particular to limit the electrical consumption of UT user terminals.

[0037] Figure 3 represents steps S1 to S9 of a transaction method between a user terminal UT and a store or vending machine ST, according to one embodiment.

[0038] In step S1, a user having the mobile terminal UT comes close to the input terminal EB. The terminal EB detects the terminal UT via its first communication interface COM1. This detection occurs when the terminal UT is within radio range of the first communication interface COM1 of the terminal EB. For this purpose, the first communication interface of the terminal EB periodically transmits an initiation message RQA to activate the second communication interface COM2 in the user terminals UT located nearby.

[0039] Upon receipt of the initiation message, in step S2, the user terminal UT transmits in response via its first communication interface COM1 an identification message containing a UID identifier of the terminal UT and activates its second communication interface COM2, in step S3. Upon receipt of the identification message, in step S4, the terminal EB transmits a distance measurement request message via its second communication interface COM2. Upon receipt of the request message, the terminal UT determines a time of receipt of the request message and transmits in response via its communication interface COM2 a message containing the time of receipt of the request message. Upon receipt of the response message, the terminal EB evaluates its distance with the terminal UT on the basis of the time elapsed between the time of receipt of the request message appearing in the response message and the time of receipt of this message by the terminal UT.

[0040] According to another embodiment, the response message sent by the terminal UT does not contain the time of receipt of the request message. In this case, the terminal EB evaluates the distance with the terminal UT on the basis of the time elapsed between the time of sending the request message and the time of receipt of the response message, possibly taking into account an average time taken by the terminals to send the response message following receipt of the request message.

[0041] In step S5, the terminal EB transmits to the local server LSRV the UID identifier received from the terminal UT and the distance DT calculated between the terminal EB and the terminal UT.

[0042] In step S6, the LSRV server receives this information and determines whether the UID identifier is in an LST list created since the daily opening of the store. In step S7, if the received UID identifier is not already in the LST list, the LSRV server transmits to the remote GSRV server a payment data request RQ message corresponding to the UID identifier and containing the latter. In step S8, the GSRV server searches a global database GDB for identification and payment data relating to the received UID identifier and transmits in response the identification and payment data UPD found, corresponding to the UID identifier. In step S9, the LSRV server receives this information and stores it in an LST list in relation to the UID identifier. If the UID is not found in the GDB database, the GSRV server sends an error message to the LSRV server in response to the RQ request message.Identification data may include user identification data such as name, surname, address, telephone number, email address, date of birth and possibly an identity photograph, and loyalty data. Payment data may include the PAN number ("Primary Account Number") of a user's bank card or a cryptographic fingerprint of this number.

[0043] If the user is not referenced in the global GDB database, the user of the UT terminal may be asked at the time of purchase to provide the required identification and payment data, for example by connecting to a website indicated in the ST store.

[0044] Thanks to these provisions, a user entering the store ST can be perfectly identified, and their payment data is available to carry out a payment transaction. Note that steps S5 to S9 can be executed only if the distance DT is less than a distance threshold value. This provision prevents a user who does not enter the store from being unnecessarily listed in the LST list.

[0045] Figure 4 shows steps S11 to S20 of a transaction method executed to allow a user to make a purchase in the store ST, according to one embodiment. Steps S11 to S20 are executed by a user terminal UT and by the terminal PB, the payment terminal RT and the server LSRV installed in the store or an automatic vending machine ST.

[0046] In step S11, the user goes to the store checkout near the distance measuring terminal PB. The presence of the user's terminal UT within the radio range of the first communication interface COM1 of the terminal PB is detected by the latter. Steps S11 to S14 may be identical to steps S1 to S4. Thus, at the end of step S14, the terminal PB has the user identifier UID and the distance measurement DT with the terminal UT. In step S15, the terminal PB transmits the user identifier UID and the distance DT to the local server LSRV. In step S16, the LSRV server stores the received distance DT in association with the received identifier UID in the list LST. The LST list can be cleared each time the store closes or reopens, or periodically, by removing records that have been on the list for more than a certain period, such as one hour or half a day.In step S16, the LST server transmits the LST list to the payment terminal RT. Thus, steps S11 to S16 make it possible to update the LST list stored by the payment terminal as users arrive at the checkout.

[0047] Step S17 is triggered by a cashier following validation of a transaction amount or by a user following validation of a shopping list and when a distance DT stored in the list LST is less than a threshold value TH2. Beforehand, the user presents himself at the checkout with items to be purchased or selects one or more items from a vending machine. The payment terminal RT receives transaction data TT comprising a transaction amount calculated on the basis of the registered items. Upon validation of the transaction data TT, the payment terminal RT consults the list LST to determine the UID identifier of the user present at the checkout and the associated payment data UPD, to be used for the payment transaction.For this purpose, the LST list item associated with the DL distance lower than the TH2 threshold value is selected because it corresponds a priori to the user located in front of the checkout. The UPD payment data of the selected list item is then used to carry out the payment transaction.

[0048] According to one embodiment, the user identifier selected in step S17 may be the one associated with the smallest distance DT, i.e. corresponding to the user closest to the terminal PB. For this purpose, the list LST may be ordered according to the distances DT associated respectively with the UID identifiers of the list.

[0049] In step S18, upon selection of the payment data, the payment terminal RT issues a payment request RQ[UPD,TT] containing the selected payment data UPD and transaction data TT including in particular a transaction amount. The payment request RQ is transmitted to the server LSRV. In step S19, the server LSRV receives the request RQ, executes the payment thus specified and transmits a payment report message PRP containing status data indicating whether the payment has been accepted or refused. The payment transaction can be carried out according to an Internet payment protocol, so that the user does not need to enter the PIN code of a bank card. In this case, the payment data appearing in the list LST can include a bank card number, an expiry date and a verification code, in clear text or in the form of a cryptographic fingerprint.The PRP report message is received by the RT payment terminal. The RT payment terminal can then display a message indicating the status of the payment, accepted or refused. In step S20 (following step S18), the LSRV server can also transmit the report message to the user's UT terminal.

[0050] If in step S17 the LST list does not contain payment data that can be selected and used, the payment transaction can then be carried out in the conventional manner. Thus, a conventional payment transaction can also be carried out using a bank card payment terminal or by depositing cash.

[0051] In case UPD payment data is not selected in step S17, the user may also be asked to provide identification data and payment data for example by logging into the website of the ST store and return to the vicinity of the EB entry terminal so that his identification and payment data are loaded into the LST list.

[0052] The transaction method which has just been described thus makes it possible to carry out a transaction without any particular action by the user, apart from presenting themselves at a checkout or in front of an automatic distributor with a terminal compatible with the protocols implemented by the first and second communication interfaces COM1, COM2 and with a distance measurement application implementing these protocols.

[0053] Note that due to the high precision of the distance measurements carried out using the UWB protocol (of the order of 10 cm), the fact that a user terminal is detected at a short distance from the PB terminal implies that no other user can be between the cash register and the user whose UT terminal is associated with the payment data thus selected in the LST list.

[0054] However, user authentication may be implemented, for example in step S17, to authorize the use of the selected payment data UPD and carry out the payment transaction. Thus, the identification data associated with the selected payment data UPD may comprise a biometric fingerprint. Furthermore, the user may be prompted during payment to enter biometric information corresponding to the biometric fingerprint, using a suitable sensor BS. The biometric information to be entered by the user may be one of the following: fingerprint of one or more fingers, a palm print, a facial image, a voice recording, a photograph of an iris of one or both eyes.Following the introduction of the biometric information, a fingerprint of this information is calculated and compared with that contained in the identification data associated in the LST list with the selected UPD payment data. The user is thus authenticated if the biometric fingerprint obtained corresponds to that of the selected LST list item.

[0055] Registration steps may be provided to register a user not referenced in the GDB database. This step may be carried out with the user's terminal or at the transaction site by means of a registration terminal. For this purpose, the registration terminal comprises a bank card reader, a communication interface with a user terminal, for example of the BLE type and possibly a biometric data entry interface. The biometric data entry interface may be for example of the fingerprint or palm print sensor type, an image sensor for taking an image of the face or the iris of one or both eyes. The registration terminal may be configured to detect and establish communication with a user terminal located nearby and retrieve the UID identifier of the terminal, which will be used by the method described above.After obtaining the terminal identifier, the enrollment terminal may invite the user to insert a bank card into the reader and enter their biometric data via the biometric data entry interface. The enrollment terminal may further be configured to generate a cryptographic fingerprint of the bank card data read by the reader, and a cryptographic fingerprint of the biometric data acquired via the biometric data entry interface. The enrollment terminal may further be configured to connect to the GSRV server and transmit to it the UID identifier, the card fingerprint and the biometric data fingerprint, in order to update the GDB database for subsequent transactions. All of the transmitted data may be encrypted before transmission to the server.

[0056] Furthermore, the DT distance measurements carried out by the PB terminal and stored in the LST list can be updated, for example periodically.

[0057] According to one embodiment, the data exchanged between the RT payment terminal, the EB, PB terminals and the LSRV server are encrypted in order to ensure the integrity and confidentiality of the transmitted data.

[0058] Figures 5A, 5B illustrate distance calculation modes SS-TWR ("Single Sided - Two Way Ranging") and DS-TWR ("Double Sided - Two Way Ranging") that can be used to measure the distance between the user terminal UT and the terminal EB or PB. The messages exchanged between the terminal EB, PB and the terminal UT pass through the second communication interfaces COM2 of the terminal and the terminals EB, PB. In the calculation mode SS-TWR of Figure 5A, the terminal EB, PB sends a distance measurement request message M1 to the terminal UT, and the terminal sends in response a distance measurement response message M2 to the terminal EB, PB. The distance DT between the terminal UT and the terminal EB, PB can be evaluated by the following equation: DT = C.(TT - T1) / 2, (1) in which T1 is the time elapsed between the time of reception of the message M1 by the terminal UT and the time of transmission of the message M2 by the terminal UT, TT is the time elapsed between the time of transmission of the message M1 by the terminal EB, PB and the time of reception of the message M2 by the terminal EB, PB, and C is the speed of propagation of electromagnetic waves in the air. The time of flight (TT — T1) / 2 (= (TOF1+TOF2) / 2) corresponds to the average of the transmission time TOF1 of the message M1 and the transmission time TOF2 of the message M2 between the terminal UT and the terminal EB, PB. The duration T1 is transmitted by the terminal to the terminal EB, PB in the message M2 or in a following message. Of course, the distance DT can be transmitted in the form of a flight time, knowing that the distance DT can be deduced from the flight time by multiplication by the constant factor C.

[0059] In the DS-TWR calculation mode of Figure 5B, the terminal UT sends a distance measurement request message M3 to the terminal EB, PB, the terminal EB, PB sends a distance measurement response message M4 to the terminal in response, and the terminal sends a distance measurement response message M5 to the terminal in response. The distance DT between the terminal UT and the terminal EB, PB can be evaluated by the following equation:

[0060] DT = C.(T3'.T4' - T3.T4) / (2.(T3+T4+T3'+T4')), (2) in which T3 is the time elapsed between the time of reception of the message M3 by the terminal EB, PB and the time of transmission of the message M4 by the terminal EB, PB, T3' is the time elapsed between the time of transmission of the message M3 by the terminal UT and the time of reception of the message M4 by the terminal UT, T4 is the time elapsed between the time of reception of the message M4 by the terminal and the time of transmission of the message M5 by the terminal, and T4' is the time elapsed between the time of transmission of the message M4 by the terminal EB, PB and the time of reception of the message M5 by the terminal EB, PB. The durations T3' and T4 can be transmitted by the UT terminal to the EB, PB terminal in the M5 message or in a following message.The messages M4 and M5 may correspond to the messages M1 and M2 respectively, and the message M3 may correspond to the activation response message transmitted by the user terminal UT in response to the UWB interface activation request message transmitted by the terminal EB, PB.

[0061] In Figures 5A, 5B, the roles of the terminal UT and the terminal EB, PB can be reversed, and the terminal UT can evaluate the distance DT and transmit it to the terminal EB, PB, for example via the BLE link. Thus, the distance measurements DT can be performed in steps S4 and S14 by the user terminal UT and transmitted to the terminal EB or PB via the first or second communication interface COM1, COM2.

[0062] It will be clear to those skilled in the art that the present invention is susceptible to various variant embodiments and various applications. In particular, the invention is not limited to the conduct of payment transactions, but can be applied to other types of transactions, such as transactions involving a transport card. The invention can also be applied to the control of paid access to areas such as a performance hall, an amusement park, a boarding area in a means of transport (bus, train, plane, boat), etc. In such cases, only identification of the card may be sufficient.

Claims

CLAIMS 1. Transaction method comprising steps consisting in: transmitting by a first communication interface (COM1) of a first terminal (EB) and by a first communication interface (COM1) of a second terminal (PB), activation requests (RQA) of a second communication interface (COM2), of the "Ultra Wide Band" type, the first communication interfaces consuming less energy in a standby state than the second communication interface; receiving by the first communication interface of a terminal (EB, PB) transmitting the activation request among the first and second terminals, an activation response containing a user terminal identifier (U ID), transmitted in response to one of the activation requests, by a first communication interface of a user terminal (UT); transmitting a distance measurement request (M1, M4), by the second communication interface of the receiving terminal (EB, PB) of the activation response;receiving a distance measurement response (M2, M5) from the user terminal via the second communication interface of the terminal (EB, PB) sending the distance measurement request; determining a distance (DT) between the user terminal and the terminal receiving the distance measurement response, on the basis of a transmission time (TOF1) of the distance measurement request and / or a transmission time (TOF2) of the distance measurement response; when the terminal receiving the distance measurement response is the first terminal (EB) and the distance between the user terminal and the first terminal (EB) is less than a first threshold value (TH1), transmitting by the first terminal to a remote server (GSRV) a request (RQ[UID]) for identification data relating to the user containing the identifier of the user terminal;receiving from the remote server and storing identification and payment data (U PD), in response to the request for identification data; and when the terminal receiving the distance measurement response is the second terminal (PB) and the distance between the user terminal and the second terminal (PB) is less than a second threshold value, transmitting by a transaction terminal (RT) a payment request (PRQ) containing the identification data and transaction data (TT).; 2. Method according to claim 1, comprising steps of capturing biometric information, calculating a biometric fingerprint from the captured biometric information, and comparison of the calculated biometric fingerprint with a biometric fingerprint appearing in the stored identification data, the payment request (PRQ) being issued only if the calculated biometric fingerprint corresponds to a biometric fingerprint appearing in the stored identification data (UPD).

3. Method according to claim 1 or 2, in which the request (RQ[UID]) for identification and payment data of the user is transmitted to a remote server (GSRV) which transmits in response the identification and payment data (UPD) corresponding to the identifier (UID) of the user terminal, the identification and payment data being stored locally (LST) for a limited period.

4. Method according to one of claims 1 to 3, comprising steps of constituting a list (LST) of user terminals (UT) having transmitted an activation response, each element of the list comprising a user terminal identifier (UID) associated with the user's identification and payment data (UDP) and the distance (DT) between the user terminal and the second terminal (PB).

5. Method according to claim 4, in which the identification data transmitted in the payment request (PRQ) are those of an element of the list (LST) associated with the smallest distance (DT).

6. Method according to claim 4 or 5, in which the list (LST) is erased periodically or when all the users whose terminal identifiers appear in the list are no longer present near one of the first and second terminals (EB, PB).

7. Method according to one of claims 1 to 6, in which the first communication interface (COM1) is of the "Bluetooth Low Energy" or WiFi™ type.

8. Method according to one of claims 1 to 7, in which the distance measurement is determined: on the basis of an average value of the time (TOF1) of transmission of the distance measurement request and the time (TOF2) of transmission of the distance measurement response, or as a function of the transmission time of the distance measurement request, the transmission time of the distance measurement response, and the transmission time of the activation response transmitted by the user terminal (UT).

9. Method according to one of claims 1 to 8, wherein when the distances (DT) measured by the first terminal (EB) are greater than the second threshold value (TH1) and a transaction must be carried out, the method comprises steps consisting of: acquiring payment data via a bank card reader, and issuing by a transaction terminal (RT) a payment request containing the acquired payment data and the transaction data (TT); and / or transmitting to the user an invitation message to provide identification and payment data to the remote server (GSRV).

10. System comprising a first terminal (EB), a second terminal (PB), a transaction terminal arranged near the second terminal, a local server (LSRV) in communication with a remote server (GSRV), and connected to the transaction terminal and to the first and second terminals, the first and second terminals comprising a first communication interface (COM1) and a second communication interface (COM2) of the "Ultra Wide Band" type, the first communication interface consuming less energy in a standby state than the second communication interface, the system being configured to implement the method according to one of claims 1 to 9 with a user terminal (UT) within radio range of one or other of the first and second terminals.

11. The system of claim 10, comprising a biometric data sensor (BS) coupled to the transaction terminal (RT).

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