Communication method

Abstract

The invention relates to a communication method implemented by a terminal (T1) within a wireless communication network comprising a central equipment (AP), said method comprising: establishing a bidirectional communication path with said central equipment (AP) via at least one relay (R1) of said communication network, and upon receiving (52) at least one advertisement message (Ad) transmitted by said central equipment (AP) via a direct downlink communication channel with said terminal (T1), transmitting (53) at least one reply message (RepAd) to said advertisement message (Ad) to said central equipment via said at least one relay (R1). Figure for the abstract: Fig. 4

Description

Title of the invention: Communication method Technical field of the invention

[0001] The field of the invention is that of wireless communication systems. More specifically, the invention relates to a method of communication with a central equipment implemented by a terminal, a method of communication with a terminal implemented by a central equipment, as well as a terminal and a central equipment implementing said methods. Technological background

[0002] Prior art exists wireless communication systems that can simultaneously handle communications sent to and received from multiple terminals. Each terminal can thus communicate with an access point bidirectionally, i.e., on an uplink and a downlink.

[0003] Terminals can in particular be connected objects of the IoT type (for "Internet of Things", in English), fixed terminals (for example computers) or mobile terminals, for example of the type of smartphone, while the access point can be, for example, a base station of a wireless communication network or a residential gateway providing the interface between a local network and a network of a telecommunications operator.

[0004] The term "uplink" or "upstream" means a communication path from a terminal to an access point and the term "downlink" or "downstream" means a communication path from an access point to a terminal.

[0005] In addition, for reasons of manufacturing costs and energy savings during their operation, some terminals have limited communication capabilities and can only interact at a short distance with an access point.

[0006] To extend the communication coverage between an access point and a terminal, it is known to use multi-hop networks, for example ad-hoc, mesh, star or hierarchical networks, in order to establish a communication path between these two pieces of equipment via an intermediate piece of equipment, called a relay.

[0007] An example of such a communication network, based on the Wi-Fi Hallow standard (IEEE Std 802.11ah™-2016 Part 11, “Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications”), is shown in [Fig. 1]. This communication network includes a central piece of equipment, namely an access point (AP), Five terminals, T1, T2, T3, T4, and T5, and three relays, RI, R2, and R3, are used. In the example presented here, terminals T1, T4, and T5 are smartphones, terminal T2 is a microphone-type audio sensor, and terminal T3 is a camera-type video sensor. Thus, in this network, terminal T1 uses relay RI to communicate bidirectionally with the access point (AP). Furthermore, as shown in [Fig. 1], communication between a terminal and the access point may require the use of multiple relays. Therefore, terminal T2 communicates with the access point (AP) via relay R2 and relay RI.In this type of network, the routing of communications between terminals, relays and the access point (AP) is done in IP mode (for example in IPv4 or IPv6) possibly with the use of a protocol such as TCP ("Transmission Control Protocol"), UDP ("User Datagram Protocol") or SCTP ("Stream Control Transmission Protocol"), this list being by no means exhaustive.

[0008] Of course, such an approach can also be implemented on other types of networks than a Wi-Fi network, such as for example a mesh network of the "Thread" type ("Thread 1.4.0 Specification" accessible at https: / / www.threadgroup.org / ThreadSpec), or more generally a network not using IP mode.

[0009] When several terminals (for example terminals T1, T2, T3) use the same relay (the RI relay) to communicate with the access point, this relay constitutes a bottleneck which limits the volume of communications between the terminals and the access point.

[0010] It may therefore be desirable to provide a communication method between a terminal and an access point which makes it possible to overcome at least part of the aforementioned problem. Summary of the invention

[0011] According to a first aspect of the invention, a communication method implemented by a terminal within a wireless communication network comprising central equipment is therefore proposed, this method comprising: - the establishment of a two-way communication path with said central equipment via at least one relay of the communication network, and - upon receipt of at least one announcement message transmitted by the central equipment via a direct downlink communication channel with the terminal, the transmission of at least one reply message to the announcement message to the central equipment via said at least one relay.

[0012] The term "direct uplink" (respectively "direct downlink") means an uplink (respectively a downlink) established directly, i.e. without using a relay, between two pieces of equipment.

[0013] The proposed solution relies on a terminal identifying its ability to establish direct downlink communication with a central equipment, while the same terminal is unable to communicate uplink with that same central equipment except via a bidirectional communication path established through a relay. In other words, the terminal is within the transmission range of the central equipment, i.e., within its coverage area, but the central equipment is not within the transmission range of the terminal.

[0014] Such an asymmetric communication configuration (uplink via a relay and direct downlink) can for example be encountered when the central equipment is an access point whose range is extended by the use of multiple-input multiple-output devices, known as MIMO (“Multiple-Input Multiple-Output” in English), beamforming.

[0015] Thanks to the use of this asymmetric communication configuration, the uplink is decoupled from the downlink, which frees up bandwidth and processing capacity at the relay level.

[0016] The communication method implemented by the terminal may further include one or more of the following optional characteristics, taken individually or in any technically possible combination.

[0017] According to a first feature, the communication method implemented by the terminal further comprises the transmission to said central equipment of a request to establish a direct uplink communication channel with the central equipment, and wherein the establishment of a bidirectional communication path with the central equipment via at least one relay is carried out in the event of non-response by the central equipment to said request to establish

[0018] According to yet another feature, the communication method implemented by the terminal further includes the implementation of authentication by means of a challenge-response protocol, also known as the challenge-response protocol. In the remainder of this description, the terms "challenge" and "challenge" are used interchangeably.

[0019] According to yet another characteristic, the central equipment is an access point to said wireless communication network.

[0020] According to yet another characteristic, the terminal is a communicating object or a computer or a telephone.

[0021] According to yet another characteristic, the communication method implemented by the terminal further comprises: - the transmission of an authentication request message to the central equipment via the relay, the authentication request message including a first challenge, and - the reception of a response message to the first challenge received from the central equipment via the direct downlink communication channel with the terminal.

[0022] According to yet another feature, the communication method implemented by the terminal further includes the reception of a message comprising a second challenge received from the central equipment via the direct downlink communication channel with the terminal, and in which the authentication message further includes a response to the second challenge.

[0023] According to yet another feature, the communication method implemented by the terminal further includes the transmission of a validation message to the central equipment via the relay.

[0024] According to yet another feature, communications received via the bidirectional communication path are decrypted using a first encryption key and communications received via the direct downlink communication path with the terminal are decrypted using a second decryption key, the second key being different from the first key.

[0025] A method of communication with a terminal implemented by a central piece of equipment in a wireless communication network is also proposed, said method comprising: - the establishment of a communication path with the terminal via at least one relay of said communication network, - the transmission of an announcement message via a direct downlink communication channel with the terminal, and - the reception, via said communication channel, of at least one reply message to the announcement message.

[0026] The communication method implemented by the central equipment may further include one or more of the following optional characteristics, taken individually or in any technically possible combination.

[0027] According to a first feature, the communication method implemented by the central equipment further includes, upon receipt of at least one reply message to the announcement message, the transmission, via the direct downlink communication channel with the terminal, of a message including a first challenge.

[0028] According to another feature, the communication method implemented by the central equipment further comprises: - the reception, via said at least one relay, of an authentication message comprising a response to the first challenge and a second challenge, - the transmission of a response message to the authentication message including a response to the second challenge via the direct downlink communication channel with the terminal.

[0029] According to yet another feature, the communication process implemented by the central equipment further includes the reception of a validation message via the relay.

[0030] According to yet another feature, communications transmitted via the bidirectional communication path are encrypted using a first encryption key and communications transmitted via the direct downlink communication path with the terminal are encrypted using a second decryption key, the second key being different from the first key.

[0031] According to yet another feature, the communication process implemented by the central equipment further includes the implementation of authentication by means of a challenge-response protocol.

[0032] Accordingly, the invention also relates, according to a second aspect of the invention, to a terminal comprising at least one processor configured for: - establish a two-way communication path with a central piece of equipment in a wireless communication network via at least one relay in said communication network, and - upon receipt of at least one announcement message transmitted by said central equipment via a direct downlink communication channel with said terminal, transmit at least one reply message to said announcement message to said central equipment via said at least one relay.

[0033] According to this second aspect, the invention also relates to a central piece of equipment for a wireless communication network comprising at least one processor configured to: - establish a two-way communication path with a terminal via at least one relay of said communication network, - transmit an announcement message via a direct downlink communication channel with said terminal, and - receive, via said bidirectional communication channel, at least one reply message to said announcement message.

[0034] The characteristics and advantages of the communication method implemented by the terminal and implemented by the central equipment according to the first aspect of the invention apply respectively in the same way to the terminal and to the central equipment according to the second aspect of the invention and vice versa.

[0035] The invention also relates, according to a third aspect of the invention, to a system comprising a terminal and a central equipment according to the second aspect of the invention.

[0036] Furthermore, the processes described above can be implemented in various ways, including in wired or software form.

[0037] The invention also relates, according to a fourth aspect of the invention, to at least one computer program comprising instructions for the implementation of at least one of the processes described above, when this or these programs are executed by a processor.

[0038] This program may use any programming language, and be in the form of source code, object code, or intermediate code between source code and object code, such as in a partially compiled form, or in any other desirable form.

[0039] The invention also relates to a computer-readable information or recording medium containing the aforementioned computer program instructions. The information or recording medium may be any entity or device capable of storing programs. For example, the medium may include a storage means, such as a ROM, for example a CD-ROM or a microelectronic circuit ROM, or a magnetic recording means, for example a floppy disk or a hard drive, a DNA sequence, or flash memory. Furthermore, the information or recording medium may be a transmissible medium such as an electrical or optical signal, which may be transmitted via an electrical or optical cable, by radio link, by wireless optical link, or by other means.

[0040] The program can in particular be downloaded from an Internet-type network.

[0041] Alternatively, each information or recording medium may be an integrated circuit in which the program is incorporated, the circuit being adapted to execute or to be used in the execution of a process in accordance with the first aspect of the invention. Brief description of the figures

[0042] The invention will be better understood with the aid of the following description, given solely by way of example and made with reference to the accompanying drawings in which: - [Fig.1] is an example of a hierarchical communication network using Wi-Fi technology; - [Fig.2] schematically describes the processes implemented when establishing a bidirectional communication path between the access point AP and the terminal Tl via the relay RI of the communication network described in [Fig.1]; - [Fig.3] describes, on the left diagram, the bidirectional communication path established between the access point AP and the terminal Tl, as a result of the processes described in [Fig.2] and, on the right diagram, the different communication paths when a downlink communication path between the access point AP and the terminal Tl is established in accordance with the invention; - Figure 4 schematically describes the communication process implemented by terminal T1 and the communication process implemented by access point AP of the communication network in Figure 1 to establish the unidirectional direct communication path COM3 shown on the right-hand side of Figure 3; and - [Fig.5] presents the simplified structure of a terminal Tl and the access point AP of the communication network of [Fig.1]. Detailed description of the invention

[0043] The main steps of the processes 10, 100, and 1000, implemented respectively by terminal Tl, relay RI, and access point AP of the hierarchical communication network of [Fig. 1], for establishing a bidirectional communication path between access point AP and terminal Tl via relay RI, are now presented in relation to [Fig. 2]. It should be noted that access point AP is a central piece of equipment within the meaning of the invention.

[0044] It is assumed that, prior to the execution of processes 10, 100 and 1000, a bidirectional communication path COM1, preferably secure, has been established between the relay RI and the access point AP and that all communications described below between these two pieces of equipment are carried out via this bidirectional communication path COM1.

[0045] In step 11, terminal Tl transmits an RC connection request to the communication network. This RC connection request includes information known to the communication network, for example, a unique identifier ID1 of terminal Tl. Furthermore, this RC request is transmitted in so-called "broadcast" mode, that is, to all network equipment capable of receiving it.

[0046] In one embodiment, terminal Tl listens to messages emitted by the communication network equipment. Upon receiving a message emitted by Since the RI relay indicates that it accepts connection requests from equipment not yet part of the communication network, the Tl terminal transmits the RC connection request directly to the RI relay during step 11. In other words, in this embodiment, the RC connection request is not transmitted in "broadcast" mode.

[0047] During step 101, the RI relay receives the RC connection request. Having identified, during step 102, that the RC request is a connection request from a terminal to the communication network, the RI relay transmits, during step 103, a Mint query message to the AP access point.

[0048] During step 1001, the access point AP receives the Mint query message and extracts the terminal IDl identifier from it.

[0049] During a step 1002, the access point AP verifies that the identifier ID1 corresponds to a terminal authorized to connect to the communication network.

[0050] If so, the access point AP transmits in response to the relay RI an MAI acceptance message, this MAI acceptance message including a security information Isc obtained from the ID1 identifier of the TL terminal. Security information is any information (for example, an identifier) ​​that can be subsequently used to obtain encryption keys intended for use during communications between the access point AP and the TL terminal.

[0051] During step 104, the RI relay receives the MAI acceptance message and extracts the Isc security information from this MAL acceptance message

[0052] During a step 105, the RI relay calculates a CH1 challenge and transmits it, during a step 106, to the terminal Tl by means of an acceptance message MA2. The CH1 challenge is, for example, calculated using the security information Isc.

[0053] During step 12, terminal Tl receives the acceptance message MA2 including the CH1 challenge. The reception of the CH1 challenge implicitly signals to terminal Tl that the access point AP authorizes this terminal Tl to connect to the communication network.

[0054] During step 13, terminal Tl resolves challenge CH1 and thus determines a response AN1 to this challenge CH1. During the same step 13, terminal Tl calculates another challenge CH2. The resolution of challenge CH1 and / or the calculation of challenge CH2 is performed, for example, using a security information IscTl known to terminal Tl (obtained, for example, during its initialization) and corresponding to the security information Isc. The calculation of challenge CH2 may also take challenge CH1 into account.

[0055] During a step 14, the terminal Tl transmits an MRI reply message to the RI relay, this reply message including the AN1 reply to the CH1 challenge and the CH2 challenge.

[0056] During step 107, the RI relay receives the MRI reply message.

[0057] During step 108, the RI relay checks that the AN1 response is correct, then The system resolves challenge CH2 to obtain the response AN2 to challenge CH2 before determining, from the responses AN1 and AN2, the encryption key KR1 to be used to encrypt communications with the terminal TL. Verification of the correctness of the response AN2 and / or determination of the encryption key KR1 uses, for example, the security information Isc. Determination of the encryption key KR1 may also use the response AN2.

[0058] During a step 109, the relay encrypts the AN2 response with the KR1 encryption key to obtain an encrypted CAN2 response and transmits, during a step 110, to the terminal Tl a response message MR2, this response message MR2 including the encrypted CAN2 response.

[0059] During a step 15, the terminal Tl receives the MR2 reply message and extracts from this MR2 reply message the CAN2 encrypted reply.

[0060] During a step 16, the terminal Tl determines, from the encrypted CAN2 response and possibly the security information IscTl, the encryption key KT1 to be used to encrypt communications with the relay RL

[0061] At the end of step 16, a bidirectional communication path COM2 is established between terminal Tl and relay RL. In the example described here, the bidirectional communication path COM2 is secure, that is, communications on this communication path COM2 are encrypted using the key KR1 for relay RI and the key KT1 for terminal TL.

[0062] Figure 3 on the left-hand side shows the communication paths between terminal T1 and relay RI, and between relay RI and access point AP. It should be noted in particular that a bidirectional communication path CCOM between access point AP and terminal T1 via relay RI is established through the establishment of bidirectional communication paths COM2 and C0M1.

[0063] In the example described here of an IP-mode communication network, the bidirectional communication channels C0M1 and COM2 are associated with routing table entries maintained by the terminal Tl, the relay RI and the access point AP.

[0064] Furthermore, when using this bidirectional CCOM communication path, the terminal Tl and the relay RI encrypt the communications they exchange with the keys KT1 and KR1 respectively.

[0065] We will now describe, with reference to [Fig. 4], the communication method 50 implemented by the terminal T1 and the communication method 5000 implemented by the access point AP to establish a direct unidirectional COM3 downlink communication path with the terminal TL. The COM3 path is shown on the right side of [Fig.3]. Of course, the implementation of these methods assumes that the terminal Tl is within the coverage area of ​​the access point AP.

[0066] During a step 51, the terminal Tl transmits a ReDL establishment request for a direct bidirectional communication path with the access point AP.

[0067] Since the access point AP is out of range of terminal Tl, the latter does not receive a response to its ReDL establishment request from the access point AP. Thus, a direct bidirectional communication path between terminal Tl and the access point AP cannot be established.

[0068] During a 5001 step, the access point transmits an Ad announcement message, for example in "broadcast" mode.

[0069] Since terminal Tl is in the coverage area of ​​the access point AP, terminal Tl receives, during a step 52, the Ad announcement message.

[0070] Upon receiving the advertisement message Ad, the terminal Tl transmits, in step 53, a reply message RepAd to said advertisement message Ad to the access point AP via the relay RL. In other words, the reply message RepAd is relayed by the relay RI since it is transmitted via the bidirectional communication path CCOM. Furthermore, the reply message RepAd includes the IDl identifier of the terminal TL.

[0071] During a 5002 step, the AP access point receives the RepAd response message.

[0072] Upon receiving the RepAd response message, the AP access point calculates during From step 5003, a DEFI challenge. The DEFI challenge is calculated, for example, using the security information Isc obtained from the identifier ID1.

[0073] During a step 5004, the access point transmits directly, i.e. via a direct downlink communication channel, to terminal Tl a message M including the DEF-1 challenge.

[0074] During step 54, terminal Tl receives the message M.

[0075] During step 55, terminal Tl extracts the DEFI challenge from message M and resolves the CH1 challenge, thus determining an ANS1 response to this CH1 challenge. During the same step 55, the terminal Tl calculates another challenge, DEF2. The resolution of the DEFI challenge and / or the calculation of the DEF2 challenge is performed, for example, using the IscTl security information known to the terminal TL. The calculation of the DEF2 challenge can also take the DEFI challenge into account.

[0076] During a step 56, the terminal Tl transmits an Auth authentication message to the access point AP via the RI relay, this Auth authentication message including the ANS1 response to the DEFI challenge and the DEF2 challenge.

[0077] During a 5005 step, the AP access point receives the Auth authentication message.

[0078] During step 5006, the access point (AP) verifies that the ANS1 response is correct, then resolves the DEF2 challenge to obtain the ANS2 response to that DEF2 challenge before determining, from the ANS1 and ANS2 responses, the KAP encryption key to be used to encrypt direct communications with the terminal (Tl). The verification of the correctness of the ANS2 response and / or the determination of the KAP encryption key uses, for example, the security information (Isc). The determination of the KAP encryption key may also use the ANS2 response.

[0079] During a step 5007, the access point encrypts the ANS2 response with the KAP encryption key to obtain an encrypted CANS2 response and transmits, during a step 5008, directly to terminal Tl a RepM response message, this RepM response message including an encrypted CANS2 response.

[0080] During a step 57, the terminal Tl receives the RepM response message and extracts from this RepM response message the encrypted CANS2 response.

[0081] During a step 58, the terminal Tl determines, from the encrypted CANS2 response and possibly the security information IscTl, the encryption key KTlb to be used to decrypt communications received from the access point AP.

[0082] During step 59, terminal Tl transmits a validation message MValid to the access point AP via relay RL

[0083] Following steps 59 and 5009, a unidirectional communication path COM3 is established between the access point AP and the terminal TL. In the example described here, the communication path COM3 is secure, meaning that communications on this COM3 path are encrypted using the KAP key by the access point AP and decrypted by the terminal TL using the KTlb key. Thus, the terminal TL has two keys, KT1 and KTlb, which allow it to communicate via the relay and to receive messages directly downlink from the access point AP, respectively.

[0084] Furthermore, in the example described here in IP mode, the COM3 communication path is associated with routing table entries maintained by terminal Tl and the access point AP. Thus, the AP's routing table now includes an entry related to receiving / sending messages with terminal Tl via the RI relay and an entry related to sending messages to terminal Tl via the unidirectional COM3 communication path. In this way, if the COM3 communication path becomes unavailable, the access point AP still has the ability to communicate downlink with terminal Tl via the RL relay

[0085] Finally, in relation to [Fig.5], the simplified structures of an entity are presented, for example an access point AP or a terminal Tl according to the embodiment described above.

[0086] As illustrated by [Fig.5], such an entity comprises at least one memory 71 including a buffer memory, at least one processing unit 72, equipped for example with a programmable computing machine or a dedicated computing machine, for example a processor P, and controlled by the computer program 73, implementing steps of at least one process according to at least one embodiment of the invention.

[0087] At initialization, the code instructions of the computer program 73 are, for example, loaded into a RAM memory before being executed by the processor of the processing unit 72.

[0088] If the entity is an access point, the processor of the processing unit 72 implements steps of the communication process 5000 with the terminal Tl described above, according to the instructions of the computer program 73, to: - establish a bidirectional communication path with terminal Tl via the RI relay, - transmit an Ad announcement message via a direct downlink communication channel with terminal Tl, and - receive, via the bidirectional communication path, at least one RepAd response message to said announcement message.

[0089] If the entity is terminal T1, the processor of the processing unit 72 implements steps of the communication process 50 described above, according to the instructions of the computer program 73, to: - establish a two-way communication path with the access point (AP) via the RI relay, and - upon receipt of the Ad announcement message transmitted by the AP access point via the direct downlink communication channel with the Tl terminal, transmit the RepAd reply message to said Ad announcement message to the AP access point via the RI relay.

[0090] It should also be noted that the invention is not limited to the embodiments described above. It will indeed be apparent to those skilled in the art that various modifications can be made to the embodiments described above, in light of the information just disclosed to them.

[0091] For example, in the embodiment described above, the methods of the invention can be implemented by mechanisms below the IP layer by modifying the headers of the IP packets to use the MAC (Media Access Control) sublayer and the PHY physical layer.

[0092] In the detailed presentation of the invention given above, the terms used shall not be interpreted as limiting the invention to the embodiments set forth in this description, but shall be interpreted as including all equivalents which can be foreseen by a person skilled in the art by applying their general knowledge to the implementation of the teaching which has just been disclosed to them.

Claims

Demands

1. A communication method (50) implemented by a terminal (Tl) within a wireless communication network comprising a central equipment (AP), said method comprising: - establishing a bidirectional communication path (COM1, COM2) with said central equipment (AP) via at least one relay (RI) of said communication network, and - upon receiving at least one advertisement message (Ad) transmitted by said central equipment (AP) via a direct downlink communication path with said terminal (Tl), transmitting at least one reply message (RepAd) to said advertisement message (Ad) to said central equipment (AP) via said at least one relay (RI).

2. Communication method (50) according to the preceding claim further comprising: - the transmission (56) of an authentication request message (Auth) to said central equipment (AP) via said relay (RI), said authentication request message (Auth) comprising a first challenge (DEF2), and - the reception (57) of a first challenge response message (RepM) received from said central equipment (AP) via said direct downlink communication channel with said terminal (Tl).

3. A communication method (50) according to the preceding claim further comprising the reception (54) of a message (M) comprising a second challenge (DEFI) received from said central equipment (AP) via said direct downlink communication channel with said terminal (Tl), and wherein said authentication message (Auth) further comprises a response to said second challenge (ANS1).

4. A communication method (50) according to the preceding claim, further comprising the transmission (59) of a message validation (MValid) to said central equipment (AP) via said relay (RI).

5. A communication method (50) according to any one of claims 3 to 4 wherein communications received via the two-way communication path are decrypted using a first encryption key and communications received via said direct downlink communication path with said terminal (Tl) are decrypted using a second decryption key, said second key being different from said first key.

6. A communication method (5000) with a terminal (Tl) implemented by a central equipment (AP) of a wireless communication network, said method comprising: - establishing a two-way communication path with said terminal (Tl) via at least one relay (RI) of said communication network, - transmitting (5001) an advertisement message (Ad) via a direct downlink communication channel with said terminal (Tl), and - receiving (5002), via said two-way communication path, at least one reply message (RepAd) to said advertisement message (Ad).

7. A method of communication (5000) with a terminal implemented by a central equipment (AP) of a wireless communication network according to the preceding claim, further comprising, upon receipt (5002) of said at least one reply message (RepAd) to said announcement message (Ad), the transmission (5004), via said direct downlink communication channel with said terminal (Tl), of a message (M) comprising a first challenge (DEFI).

8. A communication method implemented by a central piece of equipment in a wireless communication network according to the preceding claim, further comprising: - the reception (5005), via said at least one relay (RI), of an authentication message (Auth) comprising a response (ANS1) to said first challenge (DEFI) and a second challenge (DEF2), - the transmission (5008) of a reply message (RepM) to said authentication message (Auth) including a reply (CANS2) to said second challenge (DEF2) via said direct downlink communication channel with said terminal (Tl).

9. A communication method implemented by a central piece of equipment in a wireless communication network according to the preceding claim, further comprising the reception (5009) of a validation message (MValid) via said relay (RI).

10. A communication method (50) according to any one of claims 8 to 9 wherein communications transmitted via the two-way communication path are encrypted using a first encryption key and communications transmitted via said direct downlink communication path with said terminal (T1) are encrypted using a second decryption key, said second key being different from said first key.

11. Terminal (Tl) comprising at least one processor configured to: - establish a bidirectional communication path with a central equipment (AP) of a wireless communication network via at least one relay (RI) of said communication network, and - upon receiving at least one advertisement message (Ad) transmitted by said central equipment (AP) via a direct downlink communication path with said terminal (Tl), transmit at least one reply message (RepAd) to said advertisement message (Ad) to said central equipment via said at least one relay (RI).

12. Central equipment (AP) of a wireless communication network comprising at least one processor configured to: - establish a bidirectional communication path with a terminal (Tl) via at least one repeater (RI) of said communication network, - transmit an advertisement message (Ad) via a direct downlink communication channel with said terminal (Tl), and

13.

14. - receive, via said bidirectional communication path, at least one reply message (RepAd) to said announcement message (Ad). System comprising a terminal according to claim 11 and a central equipment according to claim 12. Computer program comprising instructions for carrying out a method according to any one of claims 1 to 10 when this program is executed by a processor.

Images