HK1238467B - Method for affiliating a cluster of electronic devices communicating via a wireless network, associated electronic device implementing said method and system - Google Patents

Description

Method for joining a cluster of electronic devices communicating via a wireless network, electronic devices implementing the method, and related systems

The present invention relates to a method for joining a cluster of communicating electronic devices, the method being implemented by a processing unit of one of the electronic devices communicating in pair via a wireless communication network.

The invention furthermore relates to a system comprising a plurality of devices for carrying out such an incorporation method.

As a preferred but non-limiting example application, the present invention is described using an example application related to the collection of quantities, such as temperature, humidity, light intensity, vibration frequency, shock, and the like, associated with containers of goods or cargo, or more generally, the internal and/or external environment of the container. According to this example application, the containers are stacked and/or piled on a storage site or traveling on a transport platform, such as a container ship, a freight train, or any other suitable transport platform. Each container collaborates with one of the communication devices. These communication devices are responsible for collecting the quantities and transmitting them via service messages to a pair of devices acting as a "cluster head" or, as the English terminology suggests, a "head." One of the tasks of the head end is to implement a specified service. Such a service may, for example, aggregate the data collected by the communication devices and transmit the aggregated data to a remote entity via a long-range or long-distance connection, such as a satellite connection or a wireless telephone connection. However, the present invention is not limited to this single example application. More generally, a "cluster head" device is responsible for implementing a given service associated with the data collected and sent by its pair, which can relate to monitoring or alarm management, either instead of or in addition to communication with a remote entity.

Today, there are numerous types or configurations of networks for communicating objects. Figure 1 schematically illustrates two examples of wireless communication networks, R1 and R2. Regardless of the network in which they operate, each communication device (also and generally referred to as a "node" in such a network) implements a communication method that enables it to exchange data and/or service messages with a third node or paired nodes. Thus, the R1 network comprises forty communication electronic devices, labeled in Figure 1: a1 to a8, b1 to b8, c1 to c8, d1 to d8, and e1 to e8. Next to these, the R2 network comprises twenty-five communication electronic devices, labeled in Figure 1: f1 to f5, g1 to g5, h1 to h5, i1 to i5, and j1 to j5.

Whether using a single-hop network (or "single-hop network" in English terms), such as, by way of example, the R2 network described in conjunction with FIG1 , or a multi-hop network (or "multi-hop network" in English terms), such as, by way of example, the R1 network described in conjunction with FIG1 , a first node, which we designate as a "source" node, can prepare a service message, represented in FIG1 by a double arrow with a single line, comprising data associated with (as a non-limiting example) a quantity measured by a sensor cooperating with the first node, and destined for a second "recipient" node.

In a single-hop network, communication between the first and second nodes is direct. In contrast, in a multi-hop network, such communication can be indirect. Thus, a message addressed to a source node can be relayed via one or more "repeater or intermediate" nodes, whose respective function is to retransmit the message originating from the source node so that it is ultimately sent to and received by the "recipient" node. Source nodes, which are capable of communicating directly or indirectly with a headend node, form "clusters" or, in English, "clusters," such as, for example, clusters C1 and C2, represented by the dashed circles in Figure 1. A "route" is generally defined as the path by which a service message originating from a first source node reaches its destination, a second recipient node, via one or more repeater nodes. Thus, according to Figure 1, a message sent from node a4 and destined for node d2 will be relayed successively via repeater nodes b4 and c3.

Communication in single-hop or multi-hop communication networks is typically accomplished via radio. Such communication is typically short-range, meaning on the order of a few to several dozen meters, so that service messages are transmitted between different nodes. If the data is destined for a server or, more generally, a remote entity, a second communication mode is implemented, for example, via GSM (Global System for Mobile Communications) or GPRS (General Packet Radio Service), or even via satellite connections.

The exchanges between nodes, the processing or calculations performed by these nodes based on the exchanged data, and the possible remote transmission of the collected data within a network or a cluster of communication devices are likewise actions that consume electrical energy.

As indicated by way of example in FIG2 , a node typically and primarily consists of an electronic device 10 comprising a processing unit 11, for example in the form of a microcontroller, cooperating with a data memory 12 and possibly a program memory 14, which may be separate. Processing unit 11 cooperates with memories 12 and 14 via an internal communication bus. Electronic device 10 typically includes one or more sensors 15 for measuring physical quantities associated with the environment of device 10. Such sensors may measure ambient temperature, humidity, or the presence and/or absence of light. Device 10 also includes first communication means 13, which cooperate with processing unit 11 and ensure wireless proximity communication with any other electronic devices 10i within communication range. It may also include second communication means 16 of the "long-range" type, also cooperating with processing unit 11. These second communication means enable such a device 10 to transmit data to a remote entity, such as an RS server, via MC messages distributed via an RR network utilizing, for example, GSM, GPRS, or satellite technology. In order to operate, that is, to enable the processing unit 11 to implement the method resulting from its execution or interpretation of the instructions of the program P recorded in the program memory 14, the device 10 includes an electrical energy source 17, for example in the form of one or more batteries. The ability of a node to communicate or simply to operate is directly related to the remaining and available energy capacity of the node.

Some operators have sought to design networks or communication methods that are implemented across nodes in a network or cluster to globally conserve the network's or cluster's electrical energy capacity. Generally speaking, a first approach involves distributing the energy costs of exchanges between nodes across the network or cluster's nodes. A second approach involves distributing the energy consumed by processing collected data, such as long-distance transmission, across a majority of nodes, thereby sharing the power consumption across multiple nodes. Therefore, regardless of whether the contactless communication network is configured using a single hop or multi-hop approach, nodes can be arbitrarily designated or upgraded as "network head" nodes or at least cluster heads, i.e., headend nodes. In conjunction with Figure 1, devices acting as headends are represented by circles drawn with lines. This refers to node d2 for network R1 and node h3 for network R2. Nodes d2 and h3 therefore function as headends for clusters C1 and C2, respectively. In this way, energy consumed, particularly the energy consumed for long-distance transmission of data collected within the network, is shared across multiple nodes. As a variant, the headends can be designated randomly, or more precisely can each randomly designate itself as a headend, provided that these headends have sufficient software and/or material components for implementing the determined service.

As an example, the "LEACH" method, such as described in particular in the document "An Application-Specific Protocol Architecture for Wireless Microsensor Networks" (W. Heinzelman, A. Chandrakasan, H. Balakrishnan - IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, VOL. 1, NO. 4, October 2002), makes it possible to randomly designate a node in a single-hop network to become the headend. The other nodes of the cluster belonging to the headend, which we will accordingly designate as "members" or, in English, "members," address their service messages to the cluster head, and therefore to the headend. In connection with FIG. 1 , each member node is represented by a circle drawn with thin lines. Thus, in network R2, headend h3 communicates directly with nodes g2 to g4, h2 and h3, and with nodes i2 to i4. The headend collects the data emitted by the different member nodes, processes it, aggregates it, and even merges it, and triggers, for example, a long-range transmission to a destination remote entity, such as the server RS described in connection with FIG. According to this known technique, once a node has assumed the role of headend, it cannot assume this role again before the expiration of a certain period of time. New member nodes are then randomly designated as headends, thereby ensuring continuity of service. In order to enable nodes, which we will designate as "free" or, in English, "loose" (represented in connection with FIG. 1 by circles drawn with double lines), to "join" the headend and thus form a new cluster or rejoin an existing one, such free nodes, located within radio range of a node being promoted or designated as headend, are arranged to receive a recruiting message MH originating from the headend, typically in the form of an indiscriminate transmission of the recruiting message MH (also known by the English name "broadcast") destined for any node within radio range of the headend. FIG1 illustrates, via network R2, the results of transmitting a message MH from node h3, designated to function as a headend. This message MH is transmitted according to a short-range broadcast mode to nodes within communication range, in this case nodes g2 to g4, h2 and h4, and nodes i2 to i4, initially free nodes, like other nodes, such as, in a non-exhaustive manner, nodes f1 to f5, represented in FIG1 by double-lined circles. Upon receiving such an incoming message MH, a free node, such as node h4, updates its data memory, which, in conjunction with its processing unit, stores therein the coordinates or identification value of the headend, i.e., the identification of node h3 associated with FIG1. The previously free device h4 becomes a member of cluster C2, represented by the thin-lined circle. Device h3, acting as a headend, becomes the recipient of any service message MS containing data collected by device h4, which has newly become a member of cluster C2, just like its other member devices, namely nodes g2, g3, g4, i2, i3, and i4. Thus, nodes g2 to g4, h2, and h4, just like nodes i2 to i4, previously free nodes, become member nodes, as indicated by the circles drawn with a single line in FIG1 . The transmission of messages MH by node h3 is limited in range. Furthermore, nodes outside of its range do not receive messages MH as intelligible messages, or even receive them altogether. In the case of a single-hop network R2, nodes outside of h3's range, such as nodes f1 to f5, g1, g5, h1, h5, i1, i5, or nodes j1 to j5, continue to be free nodes, as indicated by the circles drawn with a double line. Cluster C2 only includes node h3 acting as the head end and member nodes, that is, it has accepted the recruitment of head end h3.

The LEACH teaching, when implemented within a multi-hop network, such as network R1 described in conjunction with FIG. 1 , allows for the assumption that a node that becomes a member of a cluster including a node acting as a headend records in its respective data store the routing information, namely, the identification value of the node acting as the headend and at least the identification value of the node that relayed the headend's recruit message, and even, as a variant, the identification values of intermediate or relay nodes that are separate from the headend. Thus, as an example, node c2 records the identification value of headend d2, having directly received a recruit message MH from said node. Node b2, in addition to the identification value of node d2, also records the identification value of node c2, having relayed d2's recruit message MH for node b2.

While such an approach theoretically, or at least according to a perfect application model, allows for the conservation of global energy resources of a communication network comprising a plurality of communication nodes, in practice or in reality, and particularly depending on the use or application area of such a communication network associated with the transport of containers cooperating with electronic communication devices, such a solution remains inappropriate, or at least less effective.

In fact, taking a preferred but non-limiting example of application, the use of a wireless communication network is described, the nodes of which store, collect, and transmit metrics associated with a plurality of containers, such as containers of supplies or cargo. It is assumed that each container is associated with an electronic communication device that implements a communication method such as LEACH or a multi-hop equivalent. According to this assumption, each electronic communication device associated with a container functions as a node in a wireless network, such as network R2 described in connection with FIG. Communication between the nodes is assumed to take place via radio. While LEACH-type communication methods specify a single-hop path, and therefore each node can communicate directly with a headend, the relative arrangement of the containers, for example on a ship, at a storage facility, or on any road or rail transport platform, creates an application context in which a node designated as the headend may be unable or no longer able to fulfill its task, such as transmitting aggregated data to a destination remote unit, simply due to its location within a stack of containers. Indeed, many obstacles are posed by transport platforms and/or storage spaces, resulting from partitions or partial confinement imposed by the container's receiving structure or the interactions between the containers themselves. Stacking these containers can lead to degradation or even loss of the ability to transmit data over long distances on behalf of the headend. The risk is significant: data loss, slow data transmission, and the wasteful and inappropriate expenditure of energy to "activate" clusters whose headends are unable to effectively ensure their functionality or services. This risk is even greater in cases where the random selection of successive headends represents a less-than-effective "selection." To address this inconvenience, TRAXENS, a company associated with the French National Institute for Computer Science and Automation, has designed a particularly innovative and high-performance wireless communication network, regardless of the relative arrangement of nodes, the network's utilization or scope of application, and whether it is single-hop or multi-hop. This network makes it possible to optimize the network's global capacity to ensure services determined by the data collected by the different nodes. It primarily relies on a method for joining a cluster of communication devices according to the selected modality of a headend, if and only if these headends are truly capable of assuming their role as headend, for example, for transmitting data according to a long-range communication mode. Each node implementing such a method can decide to act as a headend, starting from the moment it knows it is in a situation where it can effectively maintain its role. Furthermore, any free node can decide whether to join or not join a cluster of nodes including the headend, which is advantageously self-designated.

Such innovation brings many advantages, among which can be mentioned:

- sharing the energy costs among the nodes of the network in an appropriate manner, thus extending the network's ability to render services unrivalled by the previously mentioned solutions;

- envisages a network of nodes that can automatically adapt and function, for example during the dispatch, storage or transport of containers each associated with an electronic device, as required by changes in the relative positioning of the nodes or by the evolution of the conditions of utilization of the nodes;

- giving priority to the robustness of services (such as data transmission over long distances), which gives each node the opportunity to determine its role in the network and to refer to the best headend according to the service considered at each moment, while minimizing conflicts or modifications of the cluster during the simultaneous selection of multiple headends located within the radio range of a common node.

While providing a significant advance, such a solution, like the previously mentioned competing solutions, presents certain limitations or inconveniences, in particular if such a communication network is utilized in an application context for which the topology of the network is particularly variable (that is, for which new nodes wish to rejoin the network, or for which some nodes are displaced relative to other nodes and thus become out of radio range or even conversely out of radio communication range of members or headends of their respective and previously joined clusters).

In fact, regardless of the communication network selected, the network's routing or topology, i.e., the formation or destruction of clusters, is not updated with sufficient regularity or frequency to take into account the network's dynamics. With known solutions, if such updates were implemented with a high frequency, the number of recruitment, cluster destruction, or service messages would multiply, so that the primary purpose of saving energy consumption of network nodes would not be maintained.

The present invention addresses most of the inconveniences presented by known solutions. It constructs a particularly innovative and robust wireless communication network, including a process whereby any free node, i.e., a non-cluster head (headend) or non-cluster member, can request cluster membership on demand when the nodes comprising the network move relative to one another or when the network's topology fluctuates. This joining method can be adapted from the various networks previously described, particularly those illustrated in connection with FIG. 1 or FIG. 2 . A free node's joining request is represented by a double-line arrow. In this case, it involves node c5 or i5, which requests membership from nodes c4 and i4, respectively, members of clusters C1 and C2, whose headends are node d2 for network R1 and h3 for network R2. FIG. 1 also illustrates a variant of the present invention, according to which a free node, such as node c8, can in turn submit a joining request to a node (in this case, node c5 according to FIG. 1 ) that has previously joined cluster C1, whose cluster head is node d2.

Each node implementing the method according to the invention can therefore request membership from a member of the cluster, as needed and independently of the recruitment policy of the headend, and thus transmit service messages destined for the headend, in particular via the member nodes that have accepted the recruitment process, even though the headend is outside the radio range of the node that requested membership for transmitting the recruitment message. The invention thus makes it possible to expand the formed cluster after the recruitment process, and even to transform a single-hop network into a "pseudo-multihop network," in which the member nodes that have accepted the recruitment request are available as relay nodes for the nodes admitted to the recruitment process, for transmitting service messages.

To this end, the present invention relates to a method implemented by a processing unit of a first electronic communication device, the first electronic communication device also comprising a data memory, first communication means for ensuring wireless proximity communication with any other electronic device within communication range of a cluster comprising a plurality of electronic communication devices, the memory and the communication means cooperating with the processing unit, the data memory storing a value of an identification specific to the first electronic communication device and a current value of an identification arranged for an electronic communication device acting as a cluster head. The method comprises a step for transmitting a service message destined for the device acting as a cluster head.

In order to ensure the persistence of the cluster and prevent the risk of loss of information contained in the service message, the method includes:

- a step, prior to the transmission of the service message, for formulating and transmitting, by the first communication device, a verification message belonging to the cluster, said message encoding:

i as the identification value of the second electronic communication device of the identification of the recipient electronic communication device of the verification message belonging to the cluster;

ii. a value of the identification of the first device being the identification of the source electronic communication device of the verification message belonging to the cluster.

In order to limit the message flow, the method may provide that the step of formulating and transmitting the verification message belonging to the cluster by the first communication device before the transmission of the service message is only carried out if the test step proves that the device is authorized to join the cluster.

To demonstrate the persistence of the cluster, the method may include:

- a step for decoding said message revealing reception and inferring from it, if and only if, a message revealing reception of said verification message belonging to a cluster is received before expiration of a maximum waiting period determined for counting the transmission of verification messages belonging to a cluster:

i. The exposed value of the identification of the recipient device of the received message belonging to the cluster verification message;

ii. The value of the identification of the source device of the received message revealing the verification message belonging to the cluster.

According to this advantageous embodiment, the steps for formulating a service message and triggering the transmission of said service message are advantageously only carried out in the following cases:

- revealing that the deduced value of the identification of the recipient device of the received message belonging to the authentication message of the cluster is equal to the value of the identification of the first electronic communication device;

- the deduced value of the identification of the source device of the received message revealing the verification message belonging to a cluster is equal to the value of the identification of the second electronic communication device.

In order to expand the cluster, the joining method according to the present invention may include:

- a step for receiving a request to join message formulated and transmitted by a third electronic communication device requesting to join the cluster, said request to join message comprising the value of the identification of said third device requesting to join;

- a step for decoding said request to join message and for deducing therefrom the value of said identification of said third device requesting to join;

- a step for formulating a message revealing the receipt of the request to join, consisting in encoding within said message:

i as the value of the identification of the first device revealing the source device identification of the received message to join the request;

ii as the value of the identifier of the third device requesting to join the message revealing the identity of the recipient device of the received request to join,

iii. the current value of the identification of the fourth electronic communication device acting as cluster head, said value being read in the record,

- a step for triggering the transmission of a message by the first communication means revealing the receipt of the request to join.

In the case where it is possible to quantify the ability to ensure a service determined by the electronic device, the step for formulating a message revealing the receipt of a join request may furthermore consist in encoding a value describing the ability of the fourth electronic communication device acting as cluster head to ensure a service, said value being recorded in a record which furthermore stores the current value of the identification of said fourth electronic communication device acting as cluster head.

In order to enable the first electronic communication device to give a follow-up that is advantageous and relevant to the joining request, the invention can provide that the step for triggering the transmission of a message by the first communication means revealing the receipt of the joining request can only be implemented if: the data memory stores a record comprising the current value of the identification of the electronic communication device acting as cluster head.

The invention also provides that the first electronic communication device may even request to join a cluster. Such a situation may be due, for example, to the dissolution of a cluster of which the first device is a member. To this end, the joining method according to the invention may comprise:

- a step for formulating a request to join message consisting in encoding the value of the identification of the first device acting as the identification of the device requesting to join the cluster;

- a step for triggering the transmission of said request to join message by the first communication means;

- a step for receiving, by the communication means, a message indicating receipt of a request to join message formulated and transmitted by the fifth device;

a step for decoding the message revealing the reception of a request to join message and inferring therefrom if and only if said message revealing the reception of a request to join message is received before expiry of a determined maximum waiting period for counting the transmission of said request to join message:

i. The value of the identification of the recipient device of the message that reveals the request to join the reception;

ii. the value of the identification of the sixth electronic communication device acting as the source of the received message (MAA) revealing a request to join the head of the cluster to which the fifth device belongs;

- a step, carried out if and only if said deduced value of the identification of the recipient device is equal to the value of the identification of the first device requesting to join, for entering in the record the deduced value of the identification of the sixth electronic communication device acting as cluster head as the current value of the identification of the device acting as cluster head.

Advantageously, according to this embodiment:

- said step for decoding a message revealing the receipt of a request-to-join message may further consist in deducing from said message the value of an identification of a fifth electronic communication device that is the source of said message;

- said step for updating the record may further consist in recording said inferred identification value therein as identification of an electronic device communicating on an upstream route separating the first electronic communication device requesting to join and a sixth electronic communication device acting as cluster head.

In order to transmit information, for example, relating to the environment of the first electronic communication device, destined for a device acting as a cluster head, the method according to the invention may comprise, before the step for transmitting a service message destined for the device acting as a cluster head, a step for formulating a service message by the first communication device and triggering the transmission of the service message destined for an electronic communication device whose identification value is stored by means of a record as the current value of the identification of the electronic communication device acting as the cluster head.

According to a second object, in particular for adapting an electronic communication device, the invention also relates to a computer program comprising a plurality of program instructions causing the implementation of an accession method such as that provided by the invention when it undergoes:

- is previously recorded in a program memory of an electronic device comprising, among other things, a processing unit, first communication means ensuring wireless proximity communication with any other electronic device located within a communication range, a data memory for recording a value of an identification specific to said device and for recording a current value of an identification of a device acting as a cluster head, said memory and said first communication means cooperating with said processing unit;

- is executed or interpreted by said processing unit.

According to a third aspect, the invention further relates to an electronic device comprising a processing unit, a data memory, a program memory, and first communication means for ensuring wireless proximity communication with any other electronic device within communication range, the memory and the first communication means cooperating with the processing unit, the data memory comprising a record of values for an identification specific to the device and current values for identification of devices acting as cluster heads. In order to enable the device to implement the joining method according to the invention, it advantageously comprises program instructions such as those mentioned above in its program memory.

The present invention also provides a system comprising a plurality of such electronic communication devices. According to a preferred and non-limiting example of application, such a system may advantageously comprise a plurality of containers for goods, solid, fluid or liquid, each of which is associated with an electronic communication device, each of which comprises a sensor that cooperates with a processing unit for measuring and collecting quantities associated with the internal and/or external environment of the container.

Other characteristics and advantages will appear more clearly on reading the description that follows in relation to an example of implementation given as indicative and non-limiting, and on examining the accompanying figures, in which:

- FIG. 1 already described illustrates two configuration examples of wireless communication networks, respectively single-hop and multi-hop;

- FIG. 2 , already partially described, presents the functional architecture of an electronic communication device according to the invention and an electronic communication device according to the prior art when the device is adapted for implementing a method for joining a cluster of devices communicating in pairs via a wireless communication network, said method according to the invention;

- Figure 3 presents a functional description of the joining method according to the invention.

The electronic communication device according to the present invention is similar to known devices 10 , such as the device previously described in association with FIG. 2 .

To this end, the electronic communication device according to the present invention includes a processing unit 11, which comprises one or more microcontrollers, which are responsible for, inter alia, performing data processing. The data is advantageously stored, in whole or in part, in one or more data memories 12, which are generally electrically erasable and writable. The memory 12 may advantageously include non-erasable sections that are physically isolated or simply arranged so that access via writing or erasing is prohibited, or otherwise requires an authentication procedure. Such advantageous sections of the memory 12, to which access is restricted by modification, allow for the storage of, inter alia, an identification value specific to the electronic communication device. Advantageously, but not necessarily, the device 10 may also include one or more program memories 14 for storing one or more programs P, or more generally, one or more sets of program instructions, which are understandable by the processing unit 11. Execution or interpretation of these instructions by the processing unit causes the device 10 to operate or implement a data processing method. The device 10 also includes a first communication device 13, which ensures wireless proximity communication with any other electronic device, such as device 10i, as long as the other electronic device is within communication range. Via the first communication means 13, the device 10, or more precisely its processing unit 11, can transmit and/or receive messages to or from a third device located within the communication range. Such messages can be of any nature. Among the different types of messages, we can mention, in a non-exhaustive manner, data messages MS associated with a specific service S, recruitment messages MH, and group teardown messages MR.

Certain communication devices can benefit from the electromagnetic field created by the network, drawing sufficient electrical energy from it to ensure their operation, albeit only for a short period of time. However, to ensure continuous operation and/or implement processes that require more energy, the electronic communication device 10 according to the present invention can advantageously include a suitable electrical energy source 17, which can power the processing unit 11 and any other components of the device that may require it. Such a source 17 typically consists of one or more batteries. Depending on the preferred application context, particularly related to monitoring containers, although this specific context does not limit the scope of the present invention, the electronic communication device 10 can include one or more sensors 15 that cooperate with the processing unit 11. Such sensors can measure one or more quantities associated with the internal and/or external environment of the container and generate data therefrom. By way of example, as illustrated in FIG2 , the sensors 15 can measure the temperature and/or humidity prevailing in the container, the darkness or loss of darkness in the housing to indicate an unexpected opening of the container, or even vibrations. If necessary, the one or more sensors may cooperate with a processing unit of the device via a conductor layer or probes, in particular in the case where the device 10 is placed against the outer wall of a container and it is desired to monitor the internal environment of the container with the help of the device 10. Such a device 10 may also include a clock, which is not represented in FIG2 , so that it can time the collected measurements.

Depending on the service or services that are desired to be operated with the aid of the electronic communication device according to the invention, these electronic communication devices may comprise additional and optional means. As a preferred example, the services may be:

- collecting data in the vicinity of a network node of an electronic communication device according to the invention, for example related to quantities measured by said node;

- Aggregating said data collected in the vicinity of a plurality of nodes and then crafting a message MC encoding the merged service data destined for a remote entity such as a server RS.

To transmit such messages MC, the device 10 advantageously includes a second long-distance communication device 16 that cooperates with the processing unit 11. Such communication can be achieved via the RR network, via GPRS or satellite, or even via any other suitable communication path. The various internal components of the electronic device cooperate with the processing unit 11, advantageously via a wired bus or by coupling. The device 10 may include a housing that protects the components, said housing advantageously including fixing means for placing the device 10 on a support for which monitoring is desired, in this case a container according to a preferred application example.

In order to implement the present invention, it is necessary to act on the operation of the processing unit, more precisely on the communication method implemented by the processing unit. Such a method will be described later in conjunction with Figure 3. The preferred adaptation mode is to prepare a program or more generally program instructions, which are arranged to implement the method when the program instructions are executed or interpreted by the processing unit. Advantageously, the program P is loaded into the program memory 15 during the assembly of the device, or by downloading the program into the memory 15 after the assembly stage of the device.

The invention mainly consists in implementing a single-hop network (for example a LEACH network) or advantageously a multi-hop network, for which each node consists in an electronic communication device such as the device 10 previously described.

The nodes of such a network are generally adapted or arranged to implement a method for joining a device cluster. The data memory 12 includes, in addition to the value of the identification ID specific to the electronic communication device, a record RH prepared to include the current value IDHc of the identification of the electronic communication device acting as a headend (such as the node d2 or h3 according to FIG. 1 ).

When a device chooses to join a cluster where one of its nodes functions as a headend, the joining is generally exclusive. In other words, a node cannot be a member of different clusters (i.e., each with a different headend node) for the same service. A node joining a cluster selects the best headend for that service.

However, a node can also be connected to multiple headends if the headends are assigned to implement different services, such as for example a headend for long distance data transmission (service Si) and a second headend for implementing alarm management services on site (service Sj).

To this end, as in the previously presented solution LEACH, a cluster of electronic communication devices, such as clusters C1 and C2 of networks R1 and R2 described in conjunction with FIG. 1 , includes a device acting as a headend, such as nodes d2 or h3 described in conjunction with FIG. Other devices act as members of the cluster, such as, in a non-exhaustive manner, nodes c2 or i3 described in conjunction with FIG. The role of the members is primarily to collect information, such as measurements of environmental quantities, convert them into data, and then encode this data in the form of service messages MS, destined for a headend capable of providing a specific service. This headend recognizes the service message MS and then implements the specified service S. For example, such a service could consist in aggregating data transmitted from multiple members to the headend via messages MS, and then transmitting this aggregated, or even merged, data over long distances in the form of messages MC to a destination remote entity RS.

A service message MS addressed from a cluster member to the destination headend is structured so as to include:

- Information indicating the type of message (MS, MH, MR, etc.);

- the value of the source node's (generally a member node's) identifier;

- the value of the identity of the recipient node (in this case the headend), or even the identity of an intermediate or repeater node in case of a multi-hop network;

- data (e.g. about quantities measured by device sensors);

- Possibly a redundancy code, even a cipher, or any other control information enabling a node receiving such a service message to decode said service message, utilize it or relay it.

Messages MS, like any other message circulating in the network, can trigger a receipt confirmation message MACK, which is transmitted by the message recipient to the destination source node. If no MACK message is received at the end of a specified period, or "timeout" in English, a new message MS is triggered. This is repeated for a finite number of times, at the end of which the source node considers the "route" or communication with the recipient node unavailable or no longer possible. Such a source node may decide to abandon the cluster and return to free node status, or seek to join another cluster.

The joining of a free node to a node acting as a headend is similar to the joining implemented according to the LEACH solution. However, the mode of selection of the headend and the joining of a free node to a cluster member can be very different, as foreseen, for example, by TRAXENS, a company associated with the French National Institute for Computer Science and Automation (INRIA). According to this variant, only nodes that can reliably guarantee a specific service can self-designate as headends. On their side, other nodes are free to arbitrate the competition for headends and select the headend that appears to be the best candidate for implementing the service to which they contribute.

Regardless of the selected mode of the headend, a first conceptual mode of communication devices can consist in continuously maintaining these communication devices listening to the radio communication frequency to test for the presence of messages from the paired device. Such an approach can result in significant energy consumption and place a heavy burden on the autonomy of the network as a whole. A second approach, known in English as "Wake-On-Radio" (WOR), consists in putting the nodes into a relative sleep state for most of the time their respective functions are in operation. Radio communication is particularly deactivated, as it consumes considerable electrical energy. However, such nodes can continue to perform less energy-intensive internal processing. In a cyclical manner, such nodes are woken up to listen for possible messages from the paired device or to subsequently transmit recruitment messages, service messages, etc.

FIG3 illustrates a communication method P100 implemented by a first device according to the present invention, said method P100 comprising a process for requesting to join a cluster, said device being, for example, the device 10 described in conjunction with FIG2 . Such an on-demand joining process enables a free node, such as, for example, node c5 or node i5, to proactively initiate a phase of discovering member nodes or headends in its neighborhood. Such a situation may arise, for example, from the emergence of such a free node and the subsequent formation of a cluster. It may also arise from the dismantling of a cluster, the headend node of the cluster and its member nodes becoming free, and the member nodes needing to transmit service messages destined for a new headend. Such a situation may also arise from a too great distance or non-optimal positioning between a node suitable and candidate for becoming a member and the headend, said candidate node being out of radio range or too far away in terms of hops so that a recruitment message from the headend is not sent to it.

According to the known technology, it is necessary for a node to actively start self-election or be designated as a head end, and it triggers the recruitment process so that the free node can restore the status of the member node. Therefore, precious time and energy may be wasted in sending service messages.

The present invention thus enables a free node to request attachment to the cluster, and thus indirectly to the headend, through a join request procedure.

First, a process 210 implemented by an electronic communication device 10 according to the invention implementing the method P100 is described. Such a process consists in triggering a joining procedure.

This latter step may advantageously include a preliminary step 219 of waking up the device 10, if it implements, for example, the "Wake on Radio" (WOR) technique. The process 210 includes a step 211 for formulating a request-to-join message MAR. Like the first information MAR-1, such a message includes and/or encodes the value of the identifier IDa of the device 10. This identifier is advantageously recorded in a unique manner in the storage device 12 of the device 10. The process 210 also includes a step 212 for triggering the transmission of the request-to-join message MAR by the first communication device 13, addressed to any neighboring node. Such a message MAR may encode other supplementary information IMr in the form of an additional field MAR-3.

The transmission power of such a message MAR may be predetermined and fixed. Alternatively, it may be variable, so as to be reduced, for example, as a function of the remaining energy capacity of the internal supply means 17 of the device implementing the method P100. It may also be gradual, with the transmission step 212 being iterative, if the join request continues to remain unanswered, as we will see later.

In all cases, step 212, which triggers the transmission of a request-to-join message MAR, is followed by a step 213 of waiting for the reception of a message MAA, which signals the reception of the request-to-join message MAR transmitted by the cluster's headend or a member neighbor node. The maximum waiting period for such a step 213 of the message MAA can be parameterized or determined so that, at the end of a given time, the device 10 implementing the method P100 will deem itself too isolated or poorly located to rejoin the cluster (a situation symbolized in FIG3 by the labeled connection 213 - n). Process 210 is thus interrupted at step 220. Such a step 220 can also consist in putting the device to sleep or waking up during a period determined, for example, according to a WOR technique.

When, during step 213, a message indicating the receipt of an MAA is received by device 13 (symbolized by the labeled connection 213-y in FIG. 3 ), process 210 includes step 214 for decoding the MAA message. The present invention provides for such a MAA message to include or encode, in particular, first information MAA-1, corresponding to the value of the identifier IDm of the source device of the MAA message. The MAA message also encodes the value of the identifier Ida of the source device of the join request message, as the identifier of the recipient device of the MAA message, in the form of the labeled information MAA-2 in the non-limiting example described in connection with FIG. The MAA message may also advantageously encode the upstream route Ru, in the form of the labeled information MAA-3 in FIG. This includes the values of the identifiers of the serving MS and/or the relays and/or member nodes that enrolled the MH message, between the source node of the MAA message and the headend of the cluster of which the source node is a part. Such a field MAA-3 advantageously includes at least the value of the identifier of the repeater node belonging to the route, closest to the source device of the message MAA, and the headend identifier IDH. Field MAA-4 can also or as a variant encode a downstream route that separates the source node of the message MAA from the node requesting to join. Advantageously, the message MAA can also include, as a variant or supplement, fields MAA-3 and/or MAA-4, information MAA-5 reflecting the number of hops TTL required for the upstream route Ru and even for the downstream route Rd. The message MAA can also advantageously include or encode fields MAA-6 and MAA-7, for example, values CHc1 and CHc2 associated with the headend's general ability to provide certain services, and even any other additional information IMa, in the form of the labeled field MAA-8 associated with FIG. 3 .

Step 214 therefore involves deducing from the message MAA the relevant set of information encoded in the message. If step 214 confirms that the value of the identifier encoded in field MAA-2 corresponds to the value of the identifier IDa of the device requesting the join request, the message MAA is considered to indicate receipt of the join request. Process 210 then includes step 215, which, after step 214, involves recording in the device's memory device 12 the information deduced from the message MAA, in particular the value of the identifier IDH of the headend node, and even the value of the identifier of the first node on the upstream route Ru from the node requesting the join request. This action can advantageously involve updating the record RH in the memory device 12. The value of the identifier IDH is written in particular as the current value IDHc in the record RH. The device 10 then becomes a node "joined" to the cluster of the headend node. Method P100 can then include and trigger the execution of process 120, which involves transmitting a service message MS, destined for the headend, via, in particular, the node that has affirmatively responded to the join request, that is, via the source device of the message MAA.

As previously noted, the transmission power of the preliminary join request message MAR according to the present invention can be gradually increased. The objective pursued by this embodiment is to conserve energy resources of the device 17 of the apparatus 10 according to the present invention. To implement this gradual increase, the transmission power of the message MAR is first parameterized by the processing unit for transmission of the message MAR over a narrow range using a broadcast-type technology. The first iteration of step 212 thus involves parameterizing the transmission power to a base value Pmin. At the end of the foreseen maximum waiting period at step 213, if no message MAA indicating the receipt of a join request has been received (symbolized in FIG3 by the labeled connection 213-n), step 220 is not automatically performed as in the previous embodiment. Instead, process 210 triggers a new iteration of step 212 and retransmits the message MAR at an increased transmission power of Pmin+. This increase is implemented by the processing unit, which implements process 210 via step 217, for example, according to a given multiplication factor or a determined incremental step size applied to the base power Pmin. If no MAA message is received at the end of the foreseen maximum period at step 213 (a situation symbolized in FIG3 by the labeled connection 213-n), process 210 can trigger a new iteration of step 212. Thus, one or more iterations of steps 217 and 212 can continue as long as no MAA message is received and as long as the power Pmin+ remains less than the maximum transmission power Pmax of the MAR message (a situation symbolized in FIG3 by the labeled connection 218-n). Once the maximum transmission power of the MAR message is reached at 218, the iterations stop. In this case, process 210 is interrupted at 220.

The invention provides for a variant or supplement to the embodiment previously described in connection with the progressive transmission power of the message MAR. According to this new embodiment, the step 211 of formulating the message MAR consists in integrating in said message a field MAR-2 which specifies the number of hops allowed, which we will mark below as TTL, separating the node requesting to join from the member nodes or cluster head. When said number of hops is greater than one, the invention provides for the request to join message MAR to be relayed by nodes that do not act as cluster members or headends. We will see below how such a function is made possible by describing the process 200 of the method P100 according to the invention, a process triggered upon reception of the request to join message MAR.

According to this embodiment, steps 211 and 212 of the formulation and transmission triggering of a message MAR followed by a wait-for-receive step 213 for a message MAA are jointly iterated as follows: at the end of each inactive iteration—that is, as long as no message MAA is received at step 213 (symbolized by the labeled connection 213-n in FIG3 )—the permitted hop count is incremented or multiplied at step 217. When the hop count TTL reaches a predetermined ceiling (symbolized by the labeled connection 218-y in FIG3 ) and no message is permitted to be received at step 213, process 210 triggers step 220 and aborts. The device implementing method P100 continues to be a free node. As a non-limiting example, the minimum TTL value at the first iteration of step 211 may be one, indicating that no message MAR relaying is permitted by the join requestor. At each iteration, this number may be multiplied by a given multiplication factor, such as two, until the TTL value reaches a ceiling of 16. Alternatively, the value of TTL may be incremented at each iteration, for example equal to one or any other non-zero integer. The invention further provides that the maximum waiting period foreseen at step 213 may also be progressive and modified at each iteration at step 217 .

Several embodiments of a process 200 implemented by the processing unit 11 of a device according to the present invention, such as the device 10 described in connection with FIG2 , will now be considered. Such a process 200 is described in connection with FIG3 . It is triggered during the implementation of the joining method P100 in response to the receipt of a request to join message MAR transmitted by a third device requesting to join the cluster.

Such a process 200 according to the invention thus comprises a first step 201 for receiving a request-to-join message MAR formulated and transmitted by an electronic communication device, such as the node c5 or the node i5 described in connection with FIG2 . Such a message MAR comprises or encodes, for example, in a field MAR-1, a value of an identification IDa of the device requesting to join the cluster. The method P100 further comprises a step 202 for decoding said request-to-join message MAR and thus deducing therefrom said value of the identification IDa in particular.

When the device according to the present invention receives at 201 a join request message MAR transmitted by a second device according to the present invention and requesting to join the cluster, the present invention mainly prepares for two situations, which are respectively symbolized by the marked connections 203-a and 203-b on FIG3:

the device receiving said message MAR is a member node or headend of a cluster; such a device, for example the node i4 (such as described in connection with Figures 1 and 2), which receives the message MAR transmitted from the node i5, comprises a record RH encoding the current value IDHc of the identifier IDH, in this case the identifier of the node h3 acting as headend node of the cluster C2;

-The device receiving the message MAR is a free node; such a device receiving the message MAR transmitted by the node c8, for example the node c5 (such as described in connection with Figures 1 and 2) does not include a record RH encoding the current value IDHc of the identifier IDH equal to the value of the node acting as a head node, such as d2; as a variant, such a free node may include a record RH encoding a determined value indicating that the node is not the head end or member of the cluster.

In the first scenario (connection 203-a in Figure 3), process 200 includes step 204 for formulating a message MAA, which indicates the receipt of a join request from a device requesting to join. This step 204 encodes within the message MAA (field MAA-2 in the example of Figure 3) the value of the identifier IDa originally received from the device requesting to join, as the identifier of the device to which the message MAA is addressed. As previously mentioned, this step 204 also encodes the value of the identifier IDm of the device implementing process 200 and acting as a cluster headend or member node (field MAA-1 in the example of Figure 3). Step 204 may also encode (field MAA-3 in the example of Figure 3) the value of the upstream route Ru, i.e., the identifier of the node separating the node that is to transmit the message MAA from the cluster headend of which it is to form a part. This route includes the value of the identifier IDH of the headend. Step 204 can also include encoding (according to the example fields MAA-5 and MAA-6 in FIG3 ) additional information or values describing one or more capabilities CHc1 and CHc2 that the headend uses to ensure certain services. Step 204 can also encode the downstream route Rd separating the source node of the message MAA from the node requesting to join (according to the example field MAA-4 in FIG3 ), or even additional information (according to the example field MAA-8 in FIG3 ). Process 200 then includes step 205 for triggering the transmission of the message MAA by the communication device 13 of the device 10 implementing process 200.

In the case where such a device receiving the request-to-join message MAR is a free node (the second scenario symbolized by connection 203-b in FIG3 ), the present invention provides that, advantageously, according to the first embodiment, such a device remains silent (step 207). According to a second embodiment, in particular when, according to the present invention and in step 211 of the previously described process 210, a message MAR is formulated that encodes a field specifying the number of permitted relays or hops, the present invention provides that process 200 enables, upon receipt of the message MAR, the request-to-join message MAR to be relayed by one or more nodes that do not function as a cluster headend or member. According to this embodiment, process 200 includes a step 206 for decrementing the value TTL deduced or decoded in step 202 by a predefined step size, such as one unit. Step 206 also involves comparing the decremented value of the TTL field with a floor value (zero, as a non-limiting example). If the decremented value reaches the bottom value (the situation symbolized by connection 206-n in FIG. 3 ), process 200 is interrupted at 207 and the device implementing the process continues to remain silent in response to receiving the message MAR. In the opposite case (symbolized by connection 206-y in FIG. 3 ), process 200 includes step 208 for re-encoding the information inferred from the received message MAR at 202, except for the field TTL, which is updated and takes the value TTL decremented at 206. Step 208 also triggers the transmission of the re-encoded message MAR to the device's neighborhood, just as process 210 is performed for a paired device that formulates and transmits a request-to-join message MAR. Thus, the repeater device transmits the request to join for others. Step 208 then advantageously also records in a storage device the value of the node identifier IDa for the node that relayed the message MAR.

The device according to the present invention can also relay any received message MAA revealing a message MAR, which has been previously formulated and transmitted by a third device acting as a member or headend of the cluster, in particular by implementing steps 204 and 205 of process 200 according to the present invention. To this end, process 200, which is provided by the present invention for implementation by the repeater device of the message MAA, includes a step 209 for decoding the message MAA. This step consists in determining the value of the identifier IDa of the device to which the message MAA is addressed, i.e., the identifier of the device that has transmitted the original message MAR. If this identifier value corresponds to the identifier value recorded in step 208, an iteration of step 205 is implemented, aimed at triggering the transmission of a received message revealing a join request, in order to disseminate the message MAA. Thus, more and more, via one or more repeater devices according to the present invention, the message MAA transmitted from the headend or member of the cluster can be sent to the device that originally requested to join.

By implementing a joining method P100 such as previously described, a device 10 such as described as a non-limiting example in association with FIG2 may also become a node joining a cluster. In association with FIG3 , to achieve this, such a device implements a process 210 for:

- First, formulate and transmit the message MAR requesting to join the cluster, then

- In response to said join request, taking into account the message MAA received revealing said join request, such message MAA having been formulated by a head end or member third device of the cluster, said third device also being provided with the method P100 according to the invention, more specifically the process 200, and being transmitted with the device requesting to join as destination, possibly via one or more free and/or admitted devices.

As previously mentioned in connection with Figures 1 and 2, the implementation of a single-hop network R2 or a multi-hop network R1 according to the invention mainly aims at collecting information related to the environment of the different nodes by means of sensors 15. In fact, each communication device 10 is advantageously placed facing the partition of the container. The processing unit 11 of each communication device 10 that acts as a member according to the context or as a node admitted to join by virtue of the invention is adapted to trigger the formulation and transmission of a service message MS encoding information about the environment of the device. The processing unit 11 of the device 10 that acts as a head end is adapted to receive such a service message MS, to infer said environment information from one or more members or admitted persons and to implement a service, for example by long-distance transmission of a message MC via a GPRS network or equivalent with a remote server RS as destination.

The formulation of service messages MS by member devices of a single-hop or multi-hop network based on metrics delivered by one or more sensors is generally known. In contrast, the formulation and transmission of service messages MS by devices admitted to the network, destined for the headend, within the present invention, requires an innovative process 120 for the formulation and transmission of such messages MS. FIG3 illustrates an example implementation of such a process 120.

This process 120 typically comprises, i.e., as implemented by a member node according to the prior art, a step 123 a for formulating a service message MS and a step for transmitting said message destined for the device acting as headend for the determined service S. Such a step 123 is implemented after a previous step 121 for collecting, for example, from a sensor 15, a metric associated with the temperature prevailing in the container in front of which the device 10 implementing the method P100 is placed.

Such a step 123 is also subject to the presence of a record (test symbolized by step 122 in FIG. 3 ), such as the record RH entered in the data memory 12 of the device 10 described in connection with FIG. 2 , including a value IDHc for the identification of the node or device acting as headend (the case symbolized by the connection 122 -y in FIG. 3 ), indicating that the node is a member or has been admitted to the cluster. In the opposite case (the case symbolized by the connection 122 -n in FIG. 3 ), the process is interrupted at 129 and no transmission of such a message is triggered.

Depending on whether the record RH includes a direct uplink route Ru, i.e., only a value IDHc of the head end identifier exists in the record RH, or includes an indirect uplink route Ru, i.e., the record RH also includes the value of the repeater member identifier ID’, the message MS is transmitted directly to the head end or the repeater member.

Furthermore, such transmission 123 of a service message MS may also be triggered by the reception 121b of a service message MS originating from a member of the same cluster and addressed to a device 10 implementing the joining method P100 and acting as a repeater member. Following the reception of such a service message MS originating from a member of the same cluster, step 121b may thus include a step for receiving and decoding such a message MS, and even temporarily recording the data contained in the decoded service message MS in the memory 12. The relaying of such a message MS may thus be manifested by retransmitting it at different times.

According to a preferred first embodiment, it may be relevant that, before transmitting a service message, a communication device acting as a node admitted to the cluster verifies the continuity of its admission. In fact, the cluster to which the device was admitted may have already been torn down, for example, at the initiative of the head end or after a modification of the mutual configuration of the nodes.

Process 120 therefore includes a test step 124, the purpose of which is to determine whether the device is acting as a member node or a node that is allowed to join. This state can be determined, for example, by reading a Boolean status indicator, the current value of which is recorded in the device's data memory 12 or recorded by any other technique. Such a status indicator can therefore alternately take two predetermined values, which respectively describe whether the node is a "member even head end" or "allowed to join". Therefore, step 215 of process 210 can also consist in updating the status indicator to specify that the device is a node that is allowed to join until proven otherwise. In the case where the status indicator indicates that the node is a member of the cluster (the situation illustrated by connection 124-n in Figure 3), step 123 is implemented once message MS has been formulated in 123a. In contrast, in the case where the status indicator indicates that the node is admitted to the network (the situation illustrated in FIG3 by connection 124-y), process 120 includes a step 125 for formulating a permanent verification message MAS of its admission and triggering the transmission of said message by the first communication means 13. The purpose of such a message MAS is to verify, in a subsequent step 126, that the member nodes that have previously responded to the admission request with consent are always members of the same cluster, i.e., associated with the same headend node. As indicated in FIG3 as a non-limiting example, the message MAS formulated and transmitted in 125 advantageously includes two fields MAS-1 and MAS-2 for encoding, respectively, the value of the identifier IDm of the recipient device of the message MAS and the value of the identifier IDa of the device admitted to the admission. Such a message MAS may also encode other supplementary information IMs in the form of an additional field MAS-3.

Like the process 210 comprising the reception waiting step 213 of a message revealing the reception of a request to join, the process 120 comprises the reception waiting step 126 of a message MAA formulated and transmitted by the addressee node of the message MAS revealing the reception of the message MAS.

In fact, the process 200 implemented by the device that has previously responded to the accession request with approval can advantageously include a step 202a for decoding the accession verification message MAS previously received by the first communication device in 201a. Step 202a can consist in decoding the verification message MAS in order to deduce from it the value of the identification IDa of the device from which the message MAS originated and the value of the identification of the device to which the message was addressed. When the latter corresponds to the value of the identification dedicated to the device implementing the process 200, the latter considers the message MAS to be destined for its use.

If, in 203, the device detects that it is a member of a cluster (the situation illustrated in FIG3 by connection 203-a), it then carries out step 204 and then step 205 to formulate a message MAA, which is then transmitted by the first communication means 13, indicating the receipt of the message MAS, just as the message MAA was formulated and then transmitted in response to the receipt of the request to join message MAR, to which the device responded in agreement. In the opposite case (the situation illustrated in FIG3 by connection 203-b), the device continues to remain silent in 207. Process 200 is interrupted.

On the part of the device admitted to the cluster, the maximum waiting period for such a message MAA at step 126 can be parameterized or determined such that, at the end of a given period, the admitted device considers (symbolized in FIG3 by the labeled connection 126 - n) that it is no longer admitted to the cluster. Processing 120 is therefore interrupted at step 129. The device becomes a free node again. Such a step 129 can, in particular, consist of erasing the record RH. It can also consist of putting the device to sleep or waking up during a brief period determined, for example, according to the WOR technique.

As a variant or in addition to the present invention, a lost access message MAAR can be formulated and then transmitted by the electronic communication device, in response to the receipt of a join verification message MAS when the recipient of said message MAS is no longer a member of the group, replacing the "silence" or non-transmission of the message MAA. To this end, such a device can formulate the lost access message MAAR at step 207 and trigger the transmission thereof by the first communication means.

Such a formulation of the message MAAR may consist in encoding:

- the value of the identifier IDa being the value of the identifier of the recipient device of the message MAAR;

- the value of the identification IDm of the device being the value of the identification of the source device of said message MAAR.

Like the other messages MAR, MAA, MAS or MS, such a message may comprise additional information entered into said message.

According to this variant, when during step 126 a message MAAR is received and then decoded, which indicates that the value of the identifier of the recipient device is equal to the value of the identifier IDa of the source device of the message MAS and that the value of the source identifier of said message MAAR corresponds to the value of the identifier of the recipient device of the message MAS, the process 120 ends at 129, as previously described. The device previously admitted to joining becomes a free node again.

When the message MAA, revealing the receipt of the message MAS during step 126, is received by the first communication device 13, it is decoded to infer, in particular, the contents of fields MAA-1, MAA-2, and MAA-3, thereby determining the values of the identifier IDm of the source device of the message MAA, the identifier IDa of the node admitted to joining, and the identifier IDHc of the cluster's headend node. Step 126 thus enables verification (symbolized in FIG3 by the labeled connection 126-y) that the node admitted to joining is the recipient of the message MAA, that the message MAA was transmitted by a member node that has responded to the joining request in agreement, and that the cluster is always associated with the same headend. Step 126 can also infer from the message MAA the value of the headend's capabilities for providing a specific service (e.g., encoded in fields MAA-5 or MAA-6). The present invention thus provides for an embodiment in which the node admitted to joining can confirm or rescind that these capabilities are sufficient according to pre-established criteria. Step 126 may also consist in updating the record RH in the data memory 12 in order to update the current value CHc of the capability. In the negative case, step 129 is implemented and the node admitted to the admission process terminates its admission itself. If the message MAA satisfies the expectations of the node admitted to the admission process, thus confirming the continuity of the admission, step 123 is implemented, which triggers the transmission of the service message MS.

We have already seen that, in connection with process 210, the transmission power of the preliminary accession request message MAR according to the present invention can be gradual. Advantageously, this is also true for the transmission of the message MAS. The goal sought by this embodiment is therefore to conserve the energy resources of the device 17 of the device being admitted. To implement such gradualness, the transmission power of the message MAS can first be parameterized by the processing unit for transmitting the message MAS over a small range. The first iteration of step 125 thus consists in parameterizing the transmission power to a minimum value P'min. If, at the end of the maximum waiting period foreseen in step 126, no message MAS has been received (a situation symbolized in FIG3 by the labeled connection 126-n), step 129 is not automatically implemented as in the previous embodiment. Instead, process 120 consists in triggering a new iteration of step 125 and thus retransmitting the message MAS at an increased transmission power of P'min+. This increase is implemented by a processing unit that implements process 120 via step 127 (e.g., according to a given multiplication factor or a determined incremental step size applied to the bottom power P'min). If no message MAA is received at the end of the maximum period foreseen at step 126 (a situation symbolized by the labeled connection 126-n in FIG3 ), process 120 may trigger a new iteration of step 125. One or more iterations of steps 127 and 125 may thus follow as long as no message MAS is received and as long as the power P'min+ remains less than the maximum transmit power P'max of the message MAS (a situation symbolized by the labeled connection 128-n in FIG3 ). Once the maximum transmit power of the message MAS is reached at 128 (a situation symbolized by the labeled connection 128-y in FIG3 ), the iterations cease. In this case, process 120 is interrupted at 129.

The present invention further provides that the maximum waiting period foreseen at step 126 may also be progressive and modified at each iteration at step 127 .

Furthermore, to conserve energy resources, the present invention provides for the relaying or initial transmission of, in particular, a request to join message MAR, a join verification message MAS (which indicates the receipt of a previous message MAA), or a service message MS, in a node of a network according to the present invention, such as the device 17 described in connection with FIG. 2 , to be regulated within an electronic communication device acting as a member node, a node admitted to joining, or a free node of the network to one or more minimum thresholds associated with the remaining capacity of the device 17 of the electronic communication device (e.g., depending on the type of message or whether the message is being relayed or initially transmitted). Thus, in connection with FIG. 3 , the present invention's steps for transmitting a message (i.e., in a non-limiting manner: steps 212 , 125 , 123 , 205 , or 208 ) each include or partially include a preliminary step of testing the remaining capacity relative to the relevant minimum threshold. If the remaining capacity is greater than the threshold, the transmission of the message is triggered. In the opposite case, the device implementing the joining method according to the present invention remains silent. Such a realization variant makes it possible, for example, to give priority to the transmission of service messages MS with respect to management messages MAR, MAS, MAA of the network.

According to a preferred second embodiment, a provisioning member of the present invention can, in advance, send a service message (MS) or, more generally, a relayed message, like a node being admitted to joining, with the cluster head or headend as the destination, not to confirm the persistence of its joining, but rather to confirm the persistence of its attachment to the cluster. This MAS message includes a first field, MAS-1, encoding the identity of the headend, and a field, MAS-2, encoding the identity of the member node originating the MAS message. The headend can, on behalf of the member node that has approved the joining request, transmit a MAA message, indicating receipt of the MAS authentication message and certifying its maintenance of the headend role. This MAA message can also include fields, MAA-6 and MAA-7, used, for example, to update the headend's current capability values, CHc1 and CHc2, for ensuring certain services. It comprises a field MAA-1 encoding the identification of the source head of the message and a field MAA-2 encoding the identification of the recipient node of the message. According to this preferred second embodiment, step 124 aimed at de-correlating the member nodes from the nodes admitted to joining may no longer be implemented. In fact, any member node or node admitted to joining verifies the persistence of its membership in the cluster before transmitting a message, in particular destined for the head of the cluster, by sending a verification message MAS of membership in the cluster and by receiving a message MAA revealing the reception of the verification message of membership in the cluster and proving membership in the cluster, transmitted in response to the reception of the message MAS by the recipient of the message.

Any member node or node admitted to joining can receive a message of loss of membership to the cluster (like a joining loss message MAAR), in response to the reception of a verification message MAS of membership to the cluster when the addressee of said message MAS no longer belongs to the cluster, which message is formulated and then transmitted by the electronic communication device instead of "silence" or non-transmission of the message MAA.

As a variant or supplement, the present invention provides that once a member node has responded in favor of joining the request, the node admitted to joining can advantageously operate in a manner similar or analogous to a member node that has rejoined the cluster after the recruitment message MH. The node admitted to joining can therefore receive the request-to-join message MAR and advantageously respond to the request to join by formulating and transmitting a message MAA indicating the receipt of the request-to-join message MAR.

As a variant, the present invention provides that the node that is admitted to join cannot directly respond to the join request with approval, but acts as a relay for the request so that cluster members can potentially access the join request. In the same manner, the node that is admitted to join can relay the responses of cluster members to the join request to the source node of the join request.

Regardless of the configuration of the method P100 for joining a cluster, said method, according to the invention - a preferred adaptation mode of an electronic communication device (such as the adaptation mode described in connection with FIG. 2 ) - consists in recording or loading a computer program P via a program memory 14 , said computer program P comprising a plurality of program instructions which, when executed or interpreted by a processing unit of said device, cause the implementation of said method P100 .

The invention has been described by means of a preferred application example associated with the monitoring of containers of goods, solid, fluid or liquid cargo, said containers correspondingly cooperating with electronic communication devices, such as the device 10 according to FIG. 2 , which implement an incorporation method, such as the method P100 illustrated by FIG. 3 , said devices each comprising a sensor cooperating with a processing unit for measuring and collecting quantities associated with the internal and/or external environment of said container.

Such devices can be used for any other application than that aimed at transmitting the collected data along long-distance links. They can also, as a variant or as a supplement, ensure one or more other services. To this end, as we have already mentioned previously, the data memory 12 of each device can include not only a single record RH dedicated to the determined service S, but also a plurality of records RHn forming a table, each of which is dedicated to a specific service Sn. The request to join message MAR or the service message MS, according to this variant, will include information making it possible to identify the service Sn determined and involved by each of said messages. To this end, steps 211, 123a of the joining method P100 according to the invention will be adapted in particular for encoding said information making it possible to identify the service Sn.

Furthermore, the present invention provides for a communication device to be admitted to multiple clusters for the same service upon receiving a join request via a message MAR. Thus, a table is formed of multiple records RHm, each dedicated to a particular headend. According to this variant, a device admitted to multiple admissions can select one of the headends to transmit a service message MS. This selection can be based on the headend's respective capabilities in providing the service, or even, in a non-limiting manner, on the headend's relative distance in hop count. To implement this multiple admission, step 123a for formulating the service message can advantageously encode, as the recipient's identification value, a value identifying the headend with the best capabilities or closest to the device. The corresponding value of the headend's capabilities can actually be updated—for example, based on a message MAA received and decoded at step 126 of process 120, such as that described in connection with FIG. A device admitted to admissions can thus arbitrate between clusters admitted to admissions based on various criteria, such as, by way of non-limiting example, headend capabilities, headend distance in hop count, and so forth.

Furthermore, the present invention relates to any system comprising a plurality of electronic communication devices according to the present invention. More particularly, the present invention relates to any system for the traceability of containers on storage sites or transport platforms, said system also comprising a remote entity for collecting and utilizing messages MC transmitted from one or more of said devices when said devices act as cluster heads. Such a system exhibits performance in terms of energy autonomy, robustness, and adaptability to utilization conditions that are unequal and incomparable to those imposed by known solutions, such as the LEACH method, for example. Indeed, thanks to the present invention, the utilization of cluster heads, from their selection to the implementation of one or more actions related to the determined service, is optimized, preventing any unnecessary or ineffective communications within the network or to third-party destinations.

Claims (13)

1. A method (P100) implemented by a processing unit (11) of a first electronic communication device (10), the first electronic communication device further comprising: a data storage (12); a first communication device (13), the first communication device ensuring wireless proximity communication with any other electronic communication device (10i) located within a communication range of a cluster (C1, C2) comprising a plurality of electronic communication devices (10, 10i, a1, ..., a8, b1, ..., b8, ..., j1, ..., j5), the data storage (12) and ... data storage (12, a1, ..., a1, b1, ..., j5), the data storage (12) and the first communication device ensuring wireless proximity communication with any other electronic communication device (10i) located within a communication range of a cluster (C1, C2) comprising a data storage (12, a1, ..., a1, b1, ..., j5), the data storage (12) and the first communication device ensuring wireless proximity communication with any other electronic communication device (10i) located within a communication range of a cluster (C1, C2) comprising a data storage (12, a1, ..., a1, b1, ..., j5), the data storage (12) and the first communication device ensuring wireless proximity communication The communication device (13) cooperates with the processing unit (11), the data memory (12) stores the value of the identifier (ID, IDm, IDa) dedicated to the first electronic communication device (10) and the record (RH) arranged to include the current value (IDHc) of the identifier (IDH) of the electronic communication device (d2, h3) acting as the head of the cluster (C1, C2), the method (P100) includes the step of transmitting a service message (MS) to the device acting as the head of the cluster, and the method is characterized in that it includes: - Step (125) prior to the transmission of the service message (MS), which is used by the first communication device (13) to formulate and transmit a cluster-belonging authentication message (MAS), the cluster-belonging authentication message (MAS) encoding the following: i. The value of the identifier of the second electronic communication device (MAS-1), which serves as the identifier of the recipient electronic communication device in the authentication message (MAS) belonging to the cluster; ii. The value of the identifier of the first electronic communication device (MAS-2) that serves as the identifier of the source electronic communication device of the authentication message (MAS) belonging to the cluster. 2. The method according to claim 1 (P100), wherein the step of preparing and transmitting the verification message (MAS) belonging to the cluster by the first communication device (13) prior to the transmission of the service message (MS) is performed only if the test step (124) proves that the first electronic communication device is permitted to join the cluster (C1, C2) (124-y). 3. The method according to claim 2 (P100), comprising: - Step (126) is performed only if the received message (MAA) revealing the cluster's authentication message is received before the maximum waiting period for counting the transmission of the cluster's authentication message (MAS) expires, which is used to decode the received message (MAA) revealing the cluster's authentication message and infer from it: i. The value of the recipient device's identifier (MAA-2) of the received message (MAA) that reveals the authentication message (MAS) belonging to the cluster; ii. The value (MAA-1) of the identifier of the source device of the received message (MAA) belonging to the cluster's Authentication Message (MAS); The steps for designating (123a) a service message (MS) and triggering (123) the transmission of the service message (MS) are performed only in the following cases (126-y): - The inferred value (MAA-2) of the identifier of the recipient device of the received message (MAA) that reveals the authentication message (MAS) belonging to the cluster is equal to the value of the identifier of the first electronic communication device; - The inferred value (MAA-1) of the source device identifier of the received message (MAA) that reveals the authentication message (MAS) belonging to the cluster is equal to the value of the identifier of the second electronic communication device. 4. The method according to any one of claims 1 to 3 (P100), comprising: - Step (201) for receiving a join request message (MAR) formulated and transmitted by a third electronic communication device (c5, i5) requesting to join the cluster (C1, C2), the join request message (MAR) including the value of the identifier (IDa) of the third electronic communication device (c5, i5) requesting to join; - Step (202) for decoding the join request message (MAR) and for inferring from it the value of the identifier (IDa) of the third electronic communication device requesting join; - Step (204) for developing a received message (MAA) that discloses the join request, wherein (MAA-1, MAA-2, MAA-3) are encoded within the received message (MAA) that discloses the join request: i. The value of the identifier (ID) of the first electronic communication device that serves as the identifier of the source device of the received message (MAA) of the disclosed join request; ii. The value of the identifier (IDa) of the third electronic communication device requesting to join, which serves as the identifier of the receiving device in the received message (MAA) of the disclosed join request. iii. The current value (IDHc) of the identifier (IDH) of the fourth electronic communication device acting as the cluster head, which is read from the record (RH). - Step (205) for triggering the transmission of the received message (MAA) of the disclosure of the join request via the first communication device (13). 5. The method according to claim 4 (P100), wherein the step (204) for formulating the received message (MAA) of the disclosed join request further comprises encoding (MAA-6, MAA-7) values (CHc1, CHc2) that describe the service assurance capability (CH1, CH2) of the fourth electronic communication device (d2, h3) acting as the head of the cluster (C1, C2), the values (CHc1, CHc2) being recorded in a record (RH), the record (RH) further storing the current value (IDHc) of the identifier (IDH) of the fourth electronic communication device (d2, h3) acting as the head of the cluster (C1, C2). 6. The method according to claim 4 (P100), wherein the step (205) for triggering the transmission of the message (MAA) of the received disclosure of the join request via the first communication device (13) is implemented only if the data memory (12) stores a record (RH) of the current value (IDHc) of the identifier (IDH) of the fourth electronic communication device (d2, h3) which acts as the head of the cluster (C1, C2) (203-a). 7. The method according to any one of claims 1 to 3 (P100), comprising: - The steps for formulating (211) join request message (MAR) are as follows: the value of the identifier (ID, IDa) of the first electronic communication device (c5, i5) is encoded (MAR-1) as the identifier of the device requesting to join the cluster; - Step (212) for triggering the transmission of the Join Request Message (MAR) via the first communication device (13); - Step (213) for receiving, via the first communication device (13), a message (MAA) that reveals the receipt of the join request message (MAR) issued and transmitted by the fifth electronic communication device (10i); - Step (214) is performed only if the message (MAA) revealing the reception of the Join Request Message (MAR) is received before the expiration of the maximum waiting period for counting the transmission of the Join Request Message (MAR), which is used to decode the message (MAA) revealing the reception of the Join Request Message and infer from it: i. Reveal the value of the recipient device's identifier (IDa) in the received message (MAA) requesting inclusion; ii. The value of the identifier (MAA-3, IDH) of the sixth electronic communication device, which acts as the header of the cluster to which the source fifth electronic communication device belongs, as revealed in the received message (MAA) of the join request; - Step (215) is performed if and only if the inferred value (MAA-2) of the identifier of the receiving device is equal to the value of the identifier (ID) of the first electronic communication device that is requesting to join, which is used to record in the record (RH) the inferred value of the identifier (IDH) of the sixth electronic communication device that acts as the cluster head, as the current value (IDHc) of the identifier of the device that acts as the cluster head. 8. The method according to claim 7 (P100), for which: - The step (214) for decoding the message (MAA) that reveals the received join request message further comprises inferring (MAA-1) the value of the identifier (IDm) of the source fifth electronic communication device of the message (MAA) from the message (MAA) that reveals the received join request message; - The step (215) for updating the record (RH) further includes recording the inferred identifier value therein as the identifier of the electronic communication device on the uplink route (Ru) that separates the first electronic communication device that requests to join from the sixth electronic communication device that acts as the cluster head. 9. The method (P100) according to any one of claims 1 to 3, comprising a step prior to the step of transmitting a service message (MS) to a device acting as a cluster head, for formulating (123a) the service message (MS) and triggering (123) the transmission of the service message (MS) to an electronic communication device whose identifier (IDH) value is recorded (RH) and stored as the current value (IDHc) of the identifier of the electronic communication device acting as a cluster head. 10. A program memory (14) storing a computer program (P) comprising a plurality of program instructions, said program instructions causing execution of the method (P100) according to any one of claims 1 to 9 when they undergo the following: - The program memory (14) of the electronic device (10) is pre-recorded, and the electronic device further includes: a processing unit (11); a first communication device (13) for ensuring wireless proximity communication with any other electronic device (10i) within the communication range; and a data memory (12) for recording the value of the identifier (ID) dedicated to the device and a record (RH) for including the current value of the identifier of the device acting as a cluster head, the memory (12, 14) and the first communication device (13) cooperating with the processing unit (11); -Executed or interpreted by the processing unit (11). 11. An electronic device (10) comprising: a processing unit (11); a data memory (12); a program memory (14); and a first communication device (13) for ensuring wireless proximity communication with any other electronic device (10i) within communication range, the data memory (12) and the program memory (14) and the first communication device (13) cooperating with the processing unit (11), the data memory (12) including a value dedicated to an identifier (ID) of the device and a record (RH) for including the current value of an identifier of a device acting as a cluster head, the device (10) being characterized in that it includes instructions for a program (P) according to claim 10 in the program memory (14). 12. A system for wireless communication between electronic devices, comprising a plurality of electronic devices (10, 10i) according to claim 11. 13. The system of claim 12, comprising a plurality of containers for materials, solid, fluid or liquid cargo, the containers correspondingly cooperating with electronic communication devices (10, 10i), each of which includes a sensor (15) cooperating with a processing unit (11) for measuring and collecting quantities associated with the internal and/or external environment of the containers.