FR2938718A1 - COMMUNICATION METHOD AND NETWORK IMPLEMENTING SAID METHOD - Google Patents

Abstract

The invention relates to a method of communication step by step between nodes of a network, and a network adapted for its implementation. This communication method allows nodes to send data messages to at least one node, called the collector node (102, 102 '). A routing path between any one of the nodes and each collector node is determined by the broadcast, step by step, of a message, called a management message, sent by the collector node (102, 102 '), enabling the allocation a rank at each node on a routing path with respect to the collector node (102, 102 ').

Description

The invention relates to a method of communication between electronic communication devices, called nodes, forming a network, and a network adapted to implement this method. The invention more particularly relates to a communication method adapted for the propagation of data step by step between nodes of a network. A network composed of nodes exchanging data is said to be large, if the dispersion of the nodes greatly exceeds the range of communication (wired or wireless) of each of the nodes. In such a network, it is particularly advantageous that the method of communication between the nodes allows the propagation of data step by step. Such a method allows the exchange of data from a source node to a distant destination node and can be unrelated and / or out of range of one another, via a relay node chain connected and / or within communication range of each other two by two, propagating the data 20 step by step until reaching the destination node. Such a method of routing (also called routing method) of data relies on a method of locating the nodes to determine the optimal path on which to orient a message; the optimal path being one that allows a message to reach the destination node under optimal conditions. Martin Purve, et al., Published in November / December 2001 in Volume 15 of IEEE Network, discloses step-by-step data routing methods between nodes. distributed. These methods are based on the use of the geographical position of the nodes to direct the routing of data to the desired destination. Initially, the nodes acquire their geographical position using a location system, such as for example the Global Positioning System (GPS). Then, in a second step, the nodes exchange between them the knowledge of their geographical position, in order to create tables of neighborhood between the nodes. Finally, a source node must know the geographical position of the destination node to transmit data to it, so that data propagation is carried out step by step by the best path, thanks to the insertion, in the data to be transmitted. , the geographical position of the destination node. One of the methods is to propagate the data as much as possible in the direction of the destination. These methods can only work if the nodes are all equipped with a tracking system. Global Environmental Micro Sensors (GEMS): A Revolutionary Observing System for the 21st Century - Phase II Final Report, published August 31, 2005 by NIAC (NASA Institute for Advanced Concepts), introduces a micro-sensor system ( for example high-altitude micro-balloons positioned by GPS) used to measure meteorological phenomena, and compares several methods of transporting the measurement data, either directly (for example to a ground station or to a station). satellite), or step by step (for example using the methods presented in the aforementioned Mauve document). For micro-sensors that have only a small energy autonomy, the best solution is to use a step-by-step routing, because the transmission power needed to reach a neighboring micro-sensor is often much lower than that required. to transmit live data to the final destination. However, each receiving node of a message must perform position comparisons to determine which node among its neighbors is the most appropriate for forwarding the message. All these operations are repeated at each node and for each message to propagate and are expensive in computing time and energy. There remains therefore a need for a step-by-step data routing method that is simple, efficient, economical, robust and generic. A routing method in a network of nodes is: simple, if it requires few data processing operations to be performed by nodes; efficient, if the data reaches its destination quickly, with a minimum of duplicate transmissions; economical, if it is suitable for sensor networks with low cost and low energy autonomy; robust, if it can continue to work despite unpredictable changes in network topology, and so few messages never reach their destination; generic, if the routing does not require a system of geographic location of each node, nor a complex digital processing at each node. The aim of the invention is to provide these advantages and to provide a communication method for transmitting data step by step, via at least one continuous and optimized path (in particular a shorter path), from any source node of the network up to to a predetermined destination node. The invention also aims to provide a network of nodes 15 for carrying out this method. The invention aims in particular to provide such a method and such a network that can be the subject of many different applications, and more particularly that are compatible with a very low power consumption of each node, for example by allowing a long duration network life with nodes only powered by accumulator batteries or low capacity batteries. To do this, the invention relates to a method of communication between a plurality of electronic communication devices, called nodes, of a network, adapted to transmit data messages to at least one node, called the collector node, wherein: - each node is adapted to be able to send and receive messages, - each node comprises a processing module adapted to interpret and modify a received message, - a routing path between any one of the nodes and each collection node is determined by diffusion from near to near a message, said management message, sent by each collecting node, characterized in that: - each management message comprises a digital field, said rank field, - the processing module of a node receiving a management message, compares the value of the rank field of the management message with a digital value stored in a digital memory of the node, said rank memory, if the value contained in the rank memory belongs to the set consisting of undefined values and values greater than the contents of the rank field, then the processing module increments the contents of the rank field, updates the content of the rank field, rank memory with the contents of the incremented rank field, and retransmits the management message. The method of communication step by step according to the invention has the advantage of being composed of simple actions and thus fast and economical to be executed by each node. In addition, a node does not need to have complete knowledge of the path that connects it to the collector node, but it only needs to be part of a chain of connected nodes and / or within range of each other. two by two to be able to send messages to the collector node. The method according to the invention makes it possible to automatically link, without a GPS-type positioning system or complex digital processing, nodes considered to be the closest to each other, via an optimized path considered as the shortest possible path. Messages to a sink node travel from node to node along a routing path and converge to the sink node. In addition, a method according to the invention operates without the nodes needing to receive and take into account the geographical position of the collector node receiving messages.

Advantageously and according to the invention, the processing module of each collecting node is adapted to transmit - in particular periodically - a management message containing a digital field, called session identifier field, the value of which is modified according to a relation d known order of the knots. This update (especially periodic) of the routing paths is particularly advantageous in the case of networks with variable topology over time to ensure that the paths are still valid. The optimal frequency of updating the routing paths is chosen according to the mobility dynamics of the nodes in order to avoid initiating management messages more often than necessary. Advantageously and according to the invention, the processing module of a node is adapted to record an indefinite value in its rank memory when it receives a management message whose session identifier field contains a subsequent numerical value (higher order) than the previous management message received. Thus, an initiating collector node of a management message can, by modifying the value of the session identifier field contained in the message, impose on the receiving nodes an update of the message ranks and thus of the routing paths which lead to at this collecting node. Such an undefined value can be stored in a permanent memory of the node at its manufacture (for example maximum value of the rank memory of the node).

Advantageously and according to the invention, each collecting node is adapted to include an identifier of this collecting node in each new management message that it initiates. Advantageously and according to the invention, the network comprises a plurality of collector nodes, each comprising a digital identification code, said collector node identifier, which is specific to it, stored in a permanent memory of this collector node, this collector node being adapted to include this collector node identifier in each management message it initiates. Deploying multiple collector nodes increases the number of message collection points from other nodes, thereby expanding the network area. The different collection nodes can be connected by a specific connection (wired or not) in permanent communication with each other and / or with a central station and / or regularly visited for the collection of the data they receive. Advantageously and according to the invention, the processing module of a node stores in a digital memory of the node, called collector node identifier memory, the node identifier of a collector node including a management message that it received resulted in the update of his rank memory with the smallest rank value. In the interval between the receipt of two management messages, each node sends messages to a single collector node. So there are as many subnets as there are collecting nodes. Advantageously and according to the invention, each node comprises a digital identification code, said node identifier, which is specific to it, stored in a permanent memory of this node, and each management message comprises a digital field, called a field of reference. sending node identifier, in which the node identifier of the node that issued this message is last recorded. Advantageously and according to the invention, the processing module of a node, said receiving node, having received a management message having caused the update of its rank memory, is adapted to store the value of the identifier field of node transmitting this management message in a digital memory of the receiving node, said closest node identifier memory, and replaces the contents of this field in this management message with the node identifier of the receiving node, and then retransmits the management message. Storing the node identifier of the immediately preceding node in the transmission chain makes it possible, if necessary, to avoid sending a message directly to the previous node (which may be the nearest neighbor on the shortest path leading to a collector node), thus reducing duplication of messages. Advantageously and according to the invention, each node comprises a device for measuring and recording the signal level of reception of the message, and when a node receives a management message whose field value of rank is equal to that of the rank memory, the processing module is adapted to compare the level of the reception signal with that of the preceding received message, and then to store, in the transmitter node identifier field, the identifier of the node providing the highest signal level . This criterion allows a more efficient management of the placement of the nodes on the path of the management messages. Thus, when two paths of the same length, in number of nodes, are possible for a node, the processing module stores the path through which the node receives a management message with the strongest signal level, which corresponds to the most short way to the collector node. Advantageously and according to the invention, each management message contains a digital field, called recipient identifier field (s), containing at least one node identifier of a destination node of the management message. Advantageously and according to the invention, the processing module of a receiving node of a management message compares each value of the recipient identifier field (s) with its node identifier, and the processing module is adapted to access to reserved content of the management message if and only if the node identifier corresponds to the value of the recipient identifier field (s). The communication method according to the invention is adapted to include in a content management message reserved for a particular node or a group of nodes (all individually or collectively identified in the recipient identifier field). Thus, all the receiving nodes of the message but not recipients of the message, ignore its reserved content. Such reserved content may for example consist of preventing the retransmission of the management message or forcing its retransmission.

Advantageously and according to the invention, each management message is adapted to be able to convey additional data to be read by at least one node. Advantageously and according to the invention, each management message is adapted to be able to convey at least one command to be executed by at least one node. This includes, for example, a command for reconfiguring the parameters of a node (for example the frequency of the measurements to be performed by the node, the maximum number of retransmission of a data packet before abandoning, etc.) or a command of rendering information concerning parameters of the node (for example the maximum waiting time for transmission of a management packet, the maximum waiting times for transmission and retransmission of a data packet, etc. ). Advantageously and according to the invention, the processing module of at least one node, said source node, is adapted to develop messages, called data messages, and transmit them to at least one collection node. For example, at least some of the nodes perform measurements of their environment, and then include those metrics in data messages. These data messages therefore convey data to be routed to the node (s) collector (s) adapted (s) to process these data. Advantageously and according to a first preferred embodiment of the invention, the processing module of each source node is adapted to incorporate in the data messages a collector node identifier stored in a memory of the source node. In this way, each source node sends data messages to a collector node whose storage node identifier it has stored. Advantageously and according to the invention, each transmitting node (source or not) having to transmit a data message transmits it to the node whose node identifier is stored in the node identifier memory closest to the transmitting node. . Each data message is sent for each node to a single destination node, thus allowing the uniqueness of the path taken by each message and leading to a collector node. This preferred mode of implementation of the data message routing method allows each collecting node to receive a single copy of each data message sent and does not overload the network. Advantageously and according to a second embodiment of the invention, each data message is transmitted step by step using a digital field that it contains, said rank field, such as the processing module of any node receiving a data message, compares the value contained in the rank field with that contained in its rank memory, updates the rank field with the contents of its rank memory and retransmits the message if the value contained in the Rank memory is less than that contained in the rank field. This second mode of implementation of the routing method of the data messages, based on the rank values of the nodes, makes it possible to make reliable the reception of the data at the collecting nodes, even in the case where paths are no longer valid. Indeed, the same data message can be redirected by several receiving nodes, all possessing a field of lower rank to the sending node of the message.

Advantageously and for all modes of implementation of the invention, the data messages are generated asynchronously by the source nodes and then transmitted asynchronously. Each node applies a rule for determining the instant of measurement and the instant of transmission of an associated data message. Several rules can be envisaged, such as: according to a fixed frequency, or as soon as a threshold of variation is exceeded, or as soon as a measurement command is received, ... Thus, the method according to the invention makes it possible to vary the volume of data exchanged by varying the rules to be applied by the nodes dispersed in several points of the network. The messages containing these measurements are transmitted at times to overcome the collisions between messages. Advantageously and according to the invention, the reception by a node of a data message triggers the sending by this node of a message, said service message, which constitutes an acknowledgment message if it accepts the data message. , and a non-acknowledgment message if it refuses the data message. This mechanism for acknowledging or not acknowledging the data messages makes it possible to indicate to the sender node whether a data message has been received by a node, and whether the reception is accepted or refused by this node. Its purpose is to inform a transmitting node about the status of the reception, and is used in an optional manner. In addition, it can be used indifferently in one or the other of the two modes of implementation of the routing method of the data messages presented above. Advantageously and according to the invention, a transmitting node retransmits its message only if, after a predetermined time, no service message is received. Retransmission provides another opportunity for the receiving node to be able to receive the data message in the event of a previous bad reception. Advantageously and according to the invention, a receiving node of an acknowledgment message does not reissue this service message. Indeed, an acknowledgment message is used to acknowledge an identified message exchanged between two nodes, it is not intended to be broadcast to other nodes of the network. Advantageously and according to the invention, a receiving node of a non-acknowledgment message sends a non-acknowledgment message to the collection node, until a management message is received containing an identifier field value. later session. The indication of invalidity of the path passing through this node is thus propagated each time it is used, until the path is updated. The invention also relates to a network of electronic communication devices, called nodes, adapted to transmit data messages destined for at least one node, called collector node, in which: each node comprises a transmitter and a receiver, - each node comprises a processing module adapted to interpret and modify a received message, - each collecting node is adapted to emit a message, said management message, broadcast from one to the next by the nodes, characterized in that: each message of management comprises a digital field, said rank field, - the processing module of a node receiving a management message, is adapted to compare the rank field with a digital value stored in a digital memory, said rank memory, if the value of the rank memory belongs to the set of indefinite values and values greater than the rank field, then the processing module is adapted to increment the value of the rank field, update the contents of the rank memory with the contents of the incremented rank field, and retransmit the management message. The network according to the invention is suitable for implementing the method according to the invention. Advantageously, a network according to the invention comprises a plurality of nodes, called source nodes, adapted to generate useful data to be transmitted (for example data representative of measurements), and the processing module of each source node is adapted to include these data nodes. data useful in data messages sent to at least one collection node. A plurality of nodes serves as a relay to allow the data messages of the source nodes to be able to reach the collection nodes. This mechanism of data transmission step by step makes it possible, on the one hand, to extend the size of the network without having to increase the range of communication of the nodes for example by adding nodes, and on the other hand to increase the energy autonomy of the nodes which are thus more economical to produce. In a network according to the invention, in addition to the node (s) collector (s), all other nodes can be simultaneously sources or relays. In addition, a network according to the invention may comprise several collection nodes distributed over an area, thus advantageously making it possible to increase the number of data message collection points from a plurality of source nodes. The invention extends to a network characterized by all or part of the above-mentioned characteristics in relation to a method according to the invention. The invention can be subject to many different applications. Advantageously and according to the invention, the nodes are at least partly associated with mobile structures, and the nodes are connected to each other by wireless links.

In particular, advantageously and according to the invention, said structures are freely movable with a fluid in which they are placed, so as to follow the currents. Their movements are therefore uncontrolled and generally indeterminate. For example, advantageously and according to the invention said mobile structures are aerostats placed in the Earth's atmosphere, and equipped with Earth observation means generating observation data (for example meteorological) as useful data. According to another application, mobile structures can be satellites of a constellation of satellites in space.

Thus, the nodes are associated with space systems (satellites) or aircraft, more particularly aerostats such as balloons, in particular with a node carried on board each space system or aircraft, and at least one collecting node is adapted to transmitting messages to a central station, in particular a ground station (this collector node being itself fixed with respect to the central station or with respect to the ground, or carried by a space system or an aircraft and in permanent communication link with such a central station or with such a ground station). Advantageously, especially when the nodes are associated with aircraft, at least one source node is provided with means for observing the Earth, for example means for observing weather phenomena, such as cyclones. According to an advantageous application of the invention, each source node, and in particular each transmitter node, is carried on board an aerostat. Advantageously and according to the invention, the nodes are at least partly associated with mobile structures, such as capsules, immersed in a liquid medium (such as the water of a basin, a marine environment, a river, a river a physiological medium of a living being (for example the blood or the digestive tract ...) At least one collecting node is then adapted to transmit messages to a fixed station immersed or not (this collector node being either itself even fixed, is carried by a capsule and in permanent communication connection with such a fixed station) and at least one source node is provided with means for observing said liquid medium, in particular means for observing currents of the liquid medium. the case of mobile capsules of small dimensions in a physiological medium, the invention makes it possible, for example, to appreciate the characteristics (speed, diffusion, etc.) of the circulation of said physiological medium in the body. n conceivable of the invention, the nodes are associated with terminals capable of being worn by persons (for example mobile phones, personal assistants (PDA), ...), and the transmitted data can be messages from each person carrying a terminal and / or to each person wearing a collector node. Advantageously and according to other applications of the invention, the nodes are at least partly associated with fixed structures relative to the terrestrial ground. Advantageously, for example at least one source node is then equipped with fire monitoring means. A method and a network according to the invention can be of the one-way type, as is the case for the transmission of observation data between source nodes and at least one collecting node. However, there is nothing to prevent the provision of a method and a network according to the invention which are of the bidirectional type, that is to say allow data exchanges in one direction and in the other, a collector node in a sense of transmission that can act as a source node in the other direction of transmission. The invention also relates to a method and a network characterized in combination by all or some of the characteristics mentioned above or below. Other objects, features and advantages of the invention will appear on reading the following description of some of its embodiments given solely by way of nonlimiting examples, and which refers to the appended figures in which: FIG. 1 is a schematic view of a network of nodes according to the invention; FIG. 2 is a schematic view of the internal structure of a node of a network according to the invention; FIGS. 3a, 3b and 3c are illustrative schematic views of the digital fields contained in messages exchanged between nodes of a network according to the invention, respectively applying to a management message, a data message and a service message, - FIG. flow diagram of the steps performed by a node of a network according to the invention when receiving a management message in a method according to the invention, - Figures 5a and 5b each represent a logic diagram of the steps s executed by a node of a network according to the invention when receiving a data message in a method according to the invention, respectively according to the first (preferential) and the second embodiment of the routing data frames; FIG. 6 shows an embodiment of a network according to the invention, comprising balloons and stations, and intended to be used for meteorological measurements; FIG. 7 presents a second embodiment of FIG. embodiment of a network according to the invention intended to be used for studies of aquatic currents; FIG. 8 presents a third embodiment of a network according to the invention intended to be used for fire monitoring. Figures, scales and proportions are not strictly adhered to for the sake of clarity of the illustration. In FIGS. 3a, 3b and 3c, the arrangement of the digital fields inside the messages is only an example given for purposes of illustration. In Figure 1, solid lines or dotted lines represent links between nodes. In addition, the thick lines (solid or dotted) represent the shortest routing path between the nodes resulting from the application of the method according to the invention.

In a communication network 100 according to the invention, represented in FIG. 1, the communication is carried out step by step between electronic devices, called nodes, geographically dispersed in an environment according to a topology that may be indeterminate and / or uncontrolled. . Nodes within communication range communicate via wired or wireless links 7. In the case of wired links, the nodes are interconnected by physical links (cables, optical fibers ...), the network thus forming a mesh connecting each node to a plurality of other nodes. The links described in the following description are preferably wireless links, the invention being particularly advantageous in the case of nodes interconnected by wireless links. By way of non-restrictive example, these wireless links use the propagation of electromagnetic (especially radio frequency) or acoustic waves to make possible remote communication. The network 100 according to the invention comprises different types of nodes which are differentiated by their function (s), it being understood that nothing prevents at least one node from accumulating several functions, from one transmission to another. Thus, at least one node, called the collector node 102, is a data recipient node from at least one other node, called the source node, and propagated step by step to this collector node 102. It should be noted that, when a plurality of nodes 102, 102 'collectors is deployed in a network according to the invention, the nodes 102, 102' collectors are preferably interconnected by specific links, not shown in the figures (Wired or without wire), adapted for the exclusive communication between the collecting nodes and / or between them and a central station. These specific links are intended to essentially allow the retrieval and concatenation of data in a centralized database located in a central information storage station. The other nodes 1031, 1032, 1033, 1034, 1035, 1036, 1037 (hereinafter referred to as 103, when any of these nodes) of the network 100, so-called relay nodes, have a function relaying (receiving and transmitting) data messages, allowing communication between source (s) and collector (s) nodes, and possibly between relay nodes, out of range of each other. For example, the node 1033 (Figure 1) is located between the nodes 1034 and 103 1 and serves as a relay node for communication between these nodes. The source nodes also have a function of generating data messages, for example from a measurement of their environment, and at least transmission of these data messages. A network 100 according to the invention comprises at least one source node, in particular a plurality of source nodes, and a plurality of relay nodes. Some relay nodes can act as source nodes. Some relay nodes can act as collector nodes. In a network according to the invention, each node 102, 102 'collector must be in connection with at least one other node, and at least one routing path must be established between each source node and each collector node. To do this, especially when the links 7 are of the wireless type, the density and the number of relay nodes must be sufficiently large, depending on the range of the wireless links 7. Each node, whatever its type, comprises at least one transmitter 75 and at least one receiver 76 (FIG. 2) connected to at least one antenna 74, adapted to establish wireless communication links (radiofrequency) with the other nodes. scope. In addition, each node, regardless of its type, comprises digital data storage memories. A digital memory, called node identifier memory 11, formed of a node's read-only memory, contains a digital node identifier code, making it possible to uniquely distinguish each node of the network. The contents of this memory are not erased when the node is powered off. The memories described below are memories of the node, and their content can be modified and is quickly accessible read / write. A node comprises: a digital memory, called rank memory 12, for storing a natural integer representing the rank of the node; a digital memory, called reception signal level memory 13, for storing a value representative of the reception signal level of a management message; a digital memory, called collector node identifier memory 14, for storing the identifier of the collector node to which the data messages are sent from this node; a digital memory, called session identifier memory 15, for storing a value (natural integer) representative of the current session; a digital memory, called the closest node identifier memory 16, for storing a node identifier of a node transmitting a received message.

Each node also comprises a processing module 88 adapted for interpreting received data and for extracting the contents of a memory, modifying its value or storing a value therein. A processing module 88 comprises calculation means such as a computer (not shown in the figures) and buffers for temporarily storing data necessary for a calculation or waiting to be transmitted or stored (not shown in the figures). ). In practice, the digital memories of each node are advantageously organized according to three buffers or groups of memory buffers: a first buffer or group of service buffers storing all the service data of the network: the data identifying the routing path optimal; the data identifying the other nodes in range; a second buffer or group of data packet buffers storing the data packets of the data messages to the collector node (s); a third buffer or group of acknowledgment buffers storing the acknowledgment or non-acknowledgment signals received by this node for the data of the currently transmitting data messages still present in the second buffer or group of packet buffers; data; and the acknowledgment or non-acknowledgment signals transmitted by this node for the data messages it receives.

Each node also comprises a time measurement module 77, such as a clock, at least substantially synchronized with all the nodes of the network. This module allows the node to include data representative of a time (dating) in the exchanged messages.

The source nodes most often comprise a payload composed of measuring means 10 comprising a plurality of sensors (for example: temperature sensors, hygrometry, pressure) as well as a measurement control module 89 adapted to parameterize the measurements to be made, storing the measurements made and sending the processing module 88 of the node the measurements so that they can be stored and sent to the collector node. As a variant, said measurements may consist solely of data stored in the memories of the node because of the operation of the network (rank of the node, etc.). Each node comprises bidirectional communication buses 78 connecting the processing module 88 with the other modules, as well as with the various memories of the node. A bidirectional communication bus 78 also connects the measurement control module 89 with the measurement means 10 of the node. These two-way communication buses 78 make it possible to pass data from one module to another within a node. Each node comprises a power supply module 79 connected by power cables (not shown in the figures) to the other modules of the node and allowing their supply of electricity from at least one source of electrical energy (sector, batteries, accumulators, photovoltaic cells, alternators, wind turbines, ...). The links 7 for communication between nodes constitute the medium for exchanging messages of different types. In FIG. 1, the nodes in visibility (within range) of each other are connected by at least one line (solid or dashed) symbolizing a link 7 between these nodes.

Each node is adapted to receive and retransmit management messages (FIG. 3a) making it possible to establish and / or update the topology of the network, and by this means to inform the nodes of the network that a new session is starting. . The management messages 19 are initiated exclusively by the collector node (s) 102, 102 'of the network. Each node is adapted to receive and retransmit data messages (FIG. 3b), initiated exclusively by source node (s) and including measurement data made by source node (s). (s). Each node is adapted to transmit and receive service messages (FIG. 3c). Such a message may be initiated by any type of node following receipt by the latter of a data message as confirmation that the data message has been received. The data contained in the messages exchanged between the nodes are partitioned into several digital fields. Whatever the type of message considered, it comprises a digital field, said type identifier field 24, allowing the processing module 88 of a receiving node to distinguish the type of message received, among the management messages 19, data messages and service messages. In addition, all the types of message comprise a digital field, said field of issuer node identifier, making it possible to identify, on reception, which node sent the message last, and a digital field, said field 23 of recipient identifier (s), for identifying, on reception, which node (or group of nodes) is intended for the message, thereby forcing the non-destination nodes to ignore the message at least in part. This recipient identifier field 23 may contain one and only node identifier, or a plurality of node identifiers, or an identifier of a list of nodes whose identifiers are stored by a read-only memory of the different nodes. . However, some digital message fields differ depending on the type of message being considered. Thus, a management message 19 furthermore comprises at least: a digital field, called collector node identifier field, containing the identifier of the collector node having initiated this management message; a digital field, said session identifier field 26, containing the value (natural integer), of the last session in progress for the collecting node having initiated this message; a numerical field, called rank field 27, containing the rank (natural integer) value of the management message modified by the last node sending the message. A data message 20 further comprises at least for example: a digital field, called a payload field, containing the measurement data made by the source node; and in one embodiment (second embodiment described hereinafter), a digital field, said rank field 27, and a digital field, said collector node identifier field. A service message furthermore comprises at least one digital field, called service field, containing data representative of a signal to be transmitted, for example a signal for acknowledging the reception of a data message, or a signal of not acknowledging receipt of a data message. The method according to the invention is adapted to be implemented by a network 100 described above, and makes it possible to establish an optimal routing path between any one of the nodes 103; and a node 102, 102 'collector. This optimal routing path is determined by the broadcast of a management message 19, issued by the node 102, 102 'collector. In addition, the propagation of a management message 19 from a node 102, 102 'to the other nodes node determines the topology of the network 100 and order these nodes along a path adapted to allow, in return , the propagation of data messages to this node 102, 102 'collector. A routing path consists of several segments, one segment being the portion of the routing path that separates two nodes located one after the other on the path, without being separated by another node. A vehicle management message 19, via the rank field 27, the number of segments that already counts the path from its initial end (at the node 102, 102 'collector).

In FIG. 1, each value included in a square next to a node (solid line or dotted line) represents the value contained in its rank memory 12, as determined by the method according to the invention. A full-line square, respectively dotted line, is used when a node is located on a routing path of a management message from the first node 102 collector, respectively the second node 102 'collector. Thus, the content of the rank memory 12 of the collector node 102 is equal to 0, and that of the first node 1031 located on the routing path from the first collector node 102 is 1. As shown in Figure 1, the first node The collector sends a first management message comprising a rank field 27 containing the value 0. The bold solid lines represent the routing path followed by this first management message 19. The node 1031, within the communication range of the first collector node 102, receives this message 19, increments the content of the message rank field 27 by a unit (resulting value equal to 1) and assigns it to its rank memory 12 (resultant value equal to 1), then reissues the management message 19. It should be noted that a node 102, 102 'collector ignores all the management messages that it possibly receives from the other nodes of the network 100. The nodes 1032 and 1033, within the communication range of the node 1031, receive the message from the node 1031. Each of the nodes 1032 and 1033 increments the content of the received message rank field 27 by a unit (resulting value equal to 2) and assigns it to its rank memory 12 (resultant value equal to 2). ), then reissues the management message 19. In addition, the nodes 1032 and 1033 store the node identifier of the node 1031 in their nearest node identifier memory 16, corresponding to the fact that the node 1031 is their nearest neighbor on the routing path starting with the node 102 collector.

The node 1032 (respectively 1033) ignores the management message 19 from the node 1033 (respectively 1032) because it contains a field value 27 of rank equal to that contained in its rank memory 12. In addition, the node 1031 ignores the management messages from the nodes 1032 and 1033 because they each contain a field value 27 of higher rank than the contents of its rank memory 12. Node 1034 receives management messages from nodes 1032 and 1033. The message from node 1033 being received with a higher signal level, node 1034 stores the node identifier of node 1033 in its memory 16. closest node identifier (corresponding to the fact that the node 1033 is its nearest neighbor), then increments the value contained in the message rank field 27 by a unit (resulting value equal to 3) and assigns it to the contents of its rank memory 12 (resultant value equal to 3), then reissues the management message 19. The node 1035 receives the management messages from the node 1032 and the node 1034. The node 1032 having sent a management message 19 having a field value 27 of smaller rank (value equal to 2) than that of the message sent by the node 1034 (value equal to 3), then the node 1035 stores the node identifier of the node 1032 in its closest node identifier memory 16 (corresponding to the fact that the node 1032 is its nearest neighbor). The node 1035 increments the value contained in the rank field 27 by a unit (resulting value equal to 3) and assigns it to its rank memory 12 (resultant value equal to 3), then reissues the management message 19. Nodes 1036 and 1037, within the communication range of node 1035, receive the management message 19 from node 1035. Each of nodes 1036 and 1037 increments the content of field 27 of received message rank (resulting value equal to 4) and assigns it to its rank memory 12 (resultant value equal to 4), then reissues the management message 19. In addition, the nodes 1036 and 1037 store the node identifier of the node 1035 in their closest node identifier memory 16, corresponding to the fact that the node 1035 is their nearest neighbor. In a network 100 having a plurality of nodes 102, 102 'collectors, each collector node sends a management message 19 which differs from other messages by a collector node identifier field it contains. In addition, the sending of management messages 19 by each node 102, 102 'collector is done asynchronously with respect to other collector nodes. The network 100 represented in FIG. 1 comprises two nodes 102 and 102 'collectors. Like the first collector node 102, the second collector node 102 sends a second management message 19 comprising a field 27 of rank value 0. The routing path followed by the second management message 19 is represented by dashed lines. fat. The node 1036, in communication range of the second node 102 'collector, receives this message. However, as previously described, the value contained in the rank memory 12 of the node 1036 is equal to 4. The node can be positioned on a shorter routing path if it is attached to the second node 102 'collector rather than the first node 102 collector. Therefore, the node 1036 increments the content of the message rank field 27 (resultant value equal to 1) by one unit and assigns it to the contents of its rank memory 12 (resultant value equal to 1), then re-transmits the management message 19. Nodes 1035 and 1037, within the communication range of node 1036, receive management message 19 from node 1036. For the same reason as node 1036, each of nodes 1035 and 1037 increments the content of field 27 by one. of rank of the received message (resultant value equal to 2) and assigns it to the contents of its rank memory 12 (resultant value equal to 2), then reissues the management message 19. In addition, the nodes 1035 and 1037 store the node identifier of the node 1036 in their closest node identifier memory 16, corresponding to the fact that the node 1036 is their nearest neighbor. The node 1035 (respectively 1037) ignores the management message 19 from the node 1037 (respectively 1035) because it contains a field value 27 of equal rank (value 2) to that contained in their rank memory value 12. In addition, the nodes 1036 and 1032, within the communication range of the node 1035, receive the management message 19 from the node 1035 which they ignore because the rank field 27 contains a value (2) greater than or equal to the value ( 2 and 1 respectively) contained in their rank memory 12. The node 1034, within the communication range of the node 1035, does not receive the management message 19 from the second node 102 'collector, because this management message is not re-transmitted by the node 1035. In the method according to the In the invention, a session corresponds to the time interval during which the method considers that the topology of the network 100, as determined by the broadcast of a management message by a node 102, 102 'collector, remains valid. After this time interval, the node 102, 102 'collector returns a new management message to update the network topology. Therefore, a session can also be seen as the time interval between two transmissions of a management message 19 by the same collector node 102. At the instant indicated by its time measurement module 77, a collector node 102 issues a new management message whose session identifier field 26 contains a new value. Each session has a session identifier modified with respect to the previous one according to a known order relationship of the nodes. For example, a session identifier may be an incremented value for each new session, the value being reset to 0 after reaching a maximum value. A single management message 19 is initiated by each node 102, 102 'collector for each new session, and has a new value contained in the session identifier field 26. In a network 100 having a plurality of nodes 102, 102 'collectors, a session is unique for a given collector node.

The establishment of a new session is managed asynchronously between the nodes 102, 102 'collectors. The preparation of the transmission of a management message 19 to be sent by a node 102, 102 'collector follows the following steps. First, the processing module 88 of the collector node 102 includes a predefined initial value in the rank field 27 of the management message. Then, the collector node 102, 102 'includes its collector node identifier on the one hand in the digital field of the message corresponding to the collector node identifier field, and on the other hand in the node identifier field 22. transmitter. In addition, the collector node 102, 102 'includes a predetermined initial digital value in the session identifier field. For example, it is considered in the remainder of the description that the initial value of the session identifier is 0, and that the evolution order relation of the session identifiers follows an increment of one unit each. new session established. The processing module 88 of the collector node 102 includes the value of the recipient identifier in the recipient identifier field 23, the possible values being able to correspond to a group of nodes, for example the nodes with direct communication range of the node. 102, 102 'collector (also called nodes in visibility), or a particular node. In the method according to the invention, it should be noted that for all the nodes and for all the types of message, the instant of transmission of a message by a node is determined so as to limit the collisions with other messages transmitted by distinct nodes, for example by sending the message at a random time in a predetermined time interval. Each node performs the steps of the method in the order shown in Figures 4, 5a and 5b.

According to the method described in FIG. 4, in step 31, the module 88 for processing a relay node 103; interprets that a message has been received, extracts the contents of the message type identifier field 24 and determines that it is a management message, in which case the processing module 88 then executes the message step 32.

In step 32, the processing module 88 of the node 103; determines whether it is the receipt of the first management message 19. If the node 103; receives a management message 19 for the first time, then the processing module 88 executes step 43, otherwise it executes step 33. In step 33, the processing module 88 of the node 103; retrieves the content of the destination node identifier field 23 from the message, and then executes step 34. In step 34, the processing module 88 of node 103; determines whether it receives the management message 19 by comparing the content of the recipient identifier field 23 of the message with its node identifier 25 stored in its node identifier memory 11. If the module 88 processing a node 103; determines that it is one of the recipients of the management message 19, then it executes step 35, otherwise it executes step 47. In step 35, the processing module 88 of node 103; retrieves the content of the collector node identifier field 25 and executes step 36.

In step 36, the processing module 88 of the node 103; compares the content of the collector node identifier field retrieved from the message with the value contained in the collector node memory of the node 103; If the two values are different then it executes step 39, otherwise it executes step 37. In step 37, the processing module 88 of node 103; extracts from the received message the contents of the session identifier field 26 and executes step 38. In step 38, the processing module 88 of the node 103 compares the value extracted from the session identifier field 26 of the message with the value contained in its session identifier memory. If the value from the message is earlier (according to the order relationship governing the evolution of the session identifiers) than that of the node 103, then it executes step 47. If the value from the message is identical to that memorized by the node 103 ,, then it executes the step 39. Finally, if the value from the message is later than that of the node 103 ;, then the processing module 88 of the node 103; executes step 43. In step 39, the processing module 88 of the node 103, extracts from the message the contents of the rank field 27, and then executes step 40. In step 40, the processing module 88 node 103; compares the value contained in the field 27 of rank extracted in step 39 with the value contained in the rank memory 12 of the node. If the value of the message rank field 27 is greater than or equal to the value contained in the rank memory 12, then the processing module 88 of the node 103i executes step 47. Otherwise (i.e. the value contained in the rank memory 12 is greater than the value of the message rank field 27, or is an undefined value (for example the maximum value that can be taken by this memory 12 recorded by default during manufacture in the latter) ), it performs step 41. In step 41, the processing module 88 of the node 103; The value contained in the rank memory 12 is equal to the value resulting from the incrementation of the message rank field 27 (ie value of the rank field 27 plus one unit if each incrementation is equal to one unit). If so, node 103; executes step 42. Otherwise, it executes step 43. In step 42, the processing module 88 of node 103, compares the received signal level of the message with that of the previous received message, as stored in the reception signal level memory 13. If the latter is less than or equal to the level of the message received, then the node 103; performs step 47. Otherwise, it executes step 43. In step 43, the processing module 88 of node 103; increments the value contained in the rank field 27 of the received message by one unit, then executes step 44. It should be noted that nothing precludes the provision of an increment value other than 1 if it is considered useful . In step 44, the processing module 88 of node 103 assigns the value thus incremented in step 43 to the contents of its rank memory 12, and then executes step 45.

In step 45, the processing module 88 of the node 103 replaces, in the management message, the content of the issuer node identifier field 22 by the value contained in its node identifier memory 11; stores the signal level of reception of the message (value accessible when the node receives the message, from step 31) in the memory 13 receiving signal level; extracting from the management message and storing respectively the content of the collector node identifier field 25 in the collector node identifier memory 14, the content of the session identifier field 26 in the session identifier memory, the content of the issuer node identifier field 22 in the identifier memory 16 of the nearest node. Then the processing module 88 of the node 103 executes step 46. In step 46, the processing module 88 of the node 103; retransmits the management message 19, that is to say transmits it with its transmitter 75 At step 47, the processing module 88 of the node 103; ignore the received management message, and not retransmit it.

Advantageously, a management message can convey either additional data to be read by the nodes (for example the value of the measurement frequency), or a command to be executed by the nodes (for example the start or the stop of the measurements). Therefore, a node 103, if included in the recipient (s) of a message (step 34), retrieves and stores said additional data contained in the message, and then, if necessary, executes the command associated with the message. By way of nonlimiting example, for a method according to the invention considered to operate at a low rate, the period of measurements by the source nodes can be of the order of 30 seconds, and the transmission rate of a node can be of the order of 9.5kbps. At a time determined by the time tracking module 77, the sensors equipping each source node perform measurements of their environment. The moment of measurement depends on the node considered and the rule to be applied by the nodes (according to a fixed frequency, or if a parameter exceeds a threshold, ...). The measurement control module 89 sends the measurements to the processing module 88 so that they can be stored and sent to a node 102, 102 'collector. The processing module 88 of the node 103; inserts the measurement data into the measurement data field 30 of a data message. The method according to the invention makes it possible to collect data messages sent from source nodes to at least one node 102, 102 'collector relayed step by step via relay nodes 103; The data messages of a source node are sent to the collector node 102, 102 'whose value it has stored in its collector node identifier memory 14, and these data messages take the previously defined routing path by a management message 19 to determine the optimal path to reach the node 102, 102 'collector. Preferably, the use of service messages 21 makes it possible to trace the reception of an emitted data message. Sending by a node 103; a service message 21 is performed before this node 103; does not reissue the data message (to a next node of the path). However, the use of such service messages is optional for the operation of a method according to the invention. In addition, a node 103; The transmitter retransmits a received data message only if, after a predetermined time, no service message is received. A receiving node of a service message 21 transmitting an acknowledgment signal does not reissue this service message. Finally, a receiving node of a service message 21 transmitting a non-acknowledgment signal returns a non-acknowledgment message to the sending nodes of the data messages it receives, until a new message 19 is received. management containing a subsequent session ID. This propagates the invalidity indication of a portion of the path each time a data message is received. According to a first embodiment of the routing method of the data messages 20, a data message 20 is sent by a node to the last node 103, whose node identifier it has stored in its identifier memory 16 closest node (in the previous step 45 resulting from the receipt of a management message). To do this, the processing module 88 of the node inserts its node identifier, contained in its node identifier memory 11, into the identifier field 22 of the sending node of the data message 20, and then inserts the content of the node. its nearest node identifier memory 16 in the destination node identifier field 23 of the data message 20, and then the node transmits the message. Taking the topology example of Figure 1, considering that all nodes 103; are source nodes carrying out measurements to be transmitted but assuming that the second node 102 'collector does not exist, the network having only one collector node 102, the nodes 1036 and 1037 transmit a data message 20 to the destination. node 1035, their closest neighbor. Node 1035 receives these two data messages and retransmits each of them to node 1032 its nearest neighbor. The node 1035 also transmits another data message 20 containing measurement data made by this node 1035 to the node 1032. The node 1034 also transmits a data message containing the measurements made by this node 1034 to the node 1033, his nearest neighbor. Node 1032 also transmits a data message containing the measurements made by this node 1032, as well as the three data messages from node 1035, to node 1031 its nearest neighbor. Node 1033 receives and retransmits the data message from node 1034, and also transmits a data message containing its own measurement data, all sent to node 1031, its closest neighbor. Finally, the node 1031 also transmits a data message 20 containing its own measurement data, as well as all the data messages it has received from the nodes 1037, 1036, 1035, 1032, 1034 and 1033, at its destination. of the collector node 102. The collector node 102 thus receives all the data messages from the set of nodes 103; In the case where the network comprises two nodes 102, 102 ', as shown in FIG. 1, the nodes 1032, 1033, 1034 and 1031 send their data messages to the first collector node 102 as described above. By cons, nodes 1037, 1036 and 1035 send their data messages to the second node 102 'collector as follows. Nodes 1035 and 1037 each issue a data message to node 1036, their nearest neighbor. Node 1036 transmits a data message containing its own measurement data, and re-transmits data messages from nodes 1035 and 1037, all of which are sent to the second node 102 'collector. Thus, the network collects the data messages at two points which are the nodes 102 and 102 'collectors. According to the method described in FIG. 5a, in step 49, the processing module 88 of the node 103, interprets that a message has been received, extracts from the message the value contained in the type identifier field 24 and determines that it is a data message, then, if so, executes step 50. In step 50, the processing module 88 of the node 103; extracts the contents of the destination identifier memory 22 of the message and executes step 51.

In step 51, the processing module 88 of the node 103; compares the content of the destination node identifier field 22 extracted from the message with the contents of its node identifier memory 11. If the two values are different, then the node 103; performs step 58 of stopping. Otherwise, it executes step 52. In step 52, the processing module 88 of the node 103; determines whether to accept the data message destined for it. If it accepts it, it executes step 53. If it refuses it, it executes step 57. This last case can intervene, for example, when the path is broken after the node 103, or when its outgoing message processing buffer is full. In step 53, the processing module 88 of the node 103 sends a message acknowledgment service message 21 to the transmitting node of the data message 20 and then executes step 54. At step 54, the processing module 88 of the node 103; inserts the next node identifier on the path (corresponding to the contents of the nearest node identifier memory 16) in the destination identifier field 23 of the message 20. Next, the node processing module 88 103, executes step 55. In step 55, the processing module 88 of the node 103; inserts the contents of its node identifier memory 11 in the sending node identifier field 22 of the message, and then executes step 56. In step 56, the processing module 88 of the node 103, rebroadcast the data message via its transmitter 75. In step 57, the processing module 88 of the node 103, sends a message 21 of service of non-acknowledgment of the message to the node transmitting the data message. In the stopping step 58, the processing module 88 of the node 103; ignores the received data message, and does not retransmit it. According to this first embodiment of the routing of the data messages, each data message follows a single path to the appropriate sink node, and it reaches the sink node in a single copy.

According to a second embodiment of the routing of the data messages, a data message 20 is transmitted by a node 103; to nodes in range with a smaller rank value. Thus, a data message propagates in the decreasing direction of the rank values contained in node rank memories 12 until reaching a collector node 102 (where appropriate 102 '). Taking the topology example of Figure 1, considering that all nodes 103; are source nodes carrying out measurements to be transmitted but assuming that the second node 102 'collector does not exist, the network having only one collector node 102, the nodes 1036 and 1037 transmit a data message 20 containing a value field 27 of rank equal to 4. The node 1035 receives these two messages. Since the content of its rank memory 12 is 3 and is less than the rank field 27 of each of the received messages, it re-transmits these messages by changing their field value 27 of rank to the value 3 (equal value to the contents of his memory 22 of rank). The node 1035 also transmits a data message containing its own measurement data, and containing a field 27 of rank equal to 3. The nodes 1032 and 1034 receive these three messages. But only the node 1032 will retransmit them since the value of its rank memory 12 is equal to 2 and therefore less than the values contained in the rank 27 fields of the messages received. Node 1032 also issues its own data message as well as the other three receipts, all of which now have a field value 27 of rank equal to 2, as a result of assigning the contents of rank memory 12 to the messages made. by the node 1032. The node 1034 transmits its own data message with a field content 27 of rank equal to that of its memory 12 of rank, that is to say equal to 3. The nodes 1033 and 1032 receive this message, and both will retransmit it since the value contained in their rank memory 12 is less than that contained in the rank field 27 of the message initiated by the node 1034. The node 1033 also transmits its own data message with a field 27 of rank equal to its memory 12 of rank, that is to say equal to 2. The node 1031 receives all the messages sent by the nodes 1033 and 1032 and retransmits them, as well as its own data message, to node 102 collector. Thus, a data message from the nodes 1037 and 1036 is routed by the following path: 1035 then 1032 and then 1031, to the node 102 collector. A data message from the node 1035 is routed through the following path: 1032 then 1031 to the collector node 102. A data message from the node 1034 is routed through the following paths: 1032 then 1031 to the collector node 102, and also 1033 and then 1031 to the collector node 102. A data message from node 1033 or 1032 is routed through node 1031 to the collector node 102. Finally, a data message from the node 1031 is transmitted directly to the collector node 102, without passing through an intermediate node. In the case where the network 100 comprises two nodes 102 and 102 'collectors as shown in Figure 1, the nodes 1034, 1033, 1032 and 1031 send their data messages to the first node 102 collector as described above. By cons, nodes 1037, 1036 and 1035 send their data messages to the second node 102 'collector as follows. The node 1035 transmits a data message containing its measurement data, and containing a field 27 of rank equal to 2. The nodes 1036 and 1037 receive this message. But only the node 1036 will transmit it, since the value contained in its memory 12 of rank being equal to 1, lower than that contained in the field 27 of rank of the message, while the content of the memory 12 of rank of the node 1037 is equal to 2. The node 1037 sends a data message 20 containing its own measurement data, and containing a field 27 of rank equal to 2. This message is received by the nodes 1036 and 1035. But only the node 1036 is the to reissue since the value contained in its rank memory 12 is equal to 1, and is therefore lower than that of the rank field 27 of this message. Finally, the node 1036 transmits a data message containing its own measurement data, as well as the other two messages received from the nodes 1037 and 1035, all containing a rank field 27 updated by the node 1036 and equal to 1. All of these data messages are received by the node 102 'collector. Thus, a data message from nodes 1037 and 1035 is routed through node 1036 to node 102 'collector. A data message from the node 1036 is transmitted directly to the node 102 'collector, without passing through an intermediate node. Thus, the network collects the data messages at two points which are the nodes 102 and 102 'collectors. According to the method described in FIG. 5b, in step 59, the processing module 88 of the node 103; interprets that a message has been received, extracts the contents of the type identifier field 24 and determines that it is a data message, and if so, executes step 60. In step 60, the processing module 88 of the node 103; retrieved from the data message, the value contained in the collector node identifier field, and executes step 61. In step 61, the processing module 88 of node 103; retrieved from the message the value contained in the collector node identifier field and compares it with that contained in the collector node identifier memory 14 stored in the node. If the two values are different, the processing module 88 of the node 103; performs the stopping step 70, this node 103; not being on the routing path for the collector node of this message. If they are identical, it executes step 62. In step 62, the processing module 88 of the node 103; extracts from the message the contents of the rank field 27, then executes step 63.

In step 63, the processing module 88 of the node 103; compares the value extracted from the message that was contained in the rank field 27 with the value contained in its rank memory 12. If the message value is greater than or equal to that of the node, then the node executes stop step 70. Otherwise, it executes step 64.

In step 64, the processing module 88 of the node 103 determines whether it accepts the received data message. If it refuses it, then it executes step 66. If it accepts it, then it executes step 65. In step 65, the processing module 88 of node 103; sends a message acknowledgment service message 21 to the transmitting node of the data message, and then performs step 67.

In step 66, the processing module 88 of the node 103; returns a message 21 of service of not acknowledging the message to the node transmitting the data message. In step 67, the processing module 88 of the node 103; 5 replaces, in the data message, the value of the rank field 27 by that contained in its rank memory 12, then it executes step 68. In step 68, the processing module 88 of the node 103; inserts its node identifier, contained in its node identifier memory 11, into the sending node identifier field 22 of the data message, and then executes step 69. In step 69, the module Processing node 103; retransmits the data message via its transmitter 75. In step 70 of stopping, the processing module 88 of the node 103; ignore the received data message, and not retransmit it. According to this second embodiment, a data message potentially follows several paths, and arrives in multiple copies at the node 102, 102 'collector. This redundancy of the message at the reception can make it possible to compensate for a damaged path problem. According to a first application of a network according to the invention shown in FIG. 6, the nodes are associated with aircraft moving in the air, such as probe balloons 71, while the nodes 102, 102 'are collectors fixed, for example on the ground. This embodiment allows observation of meteorological phenomena, including monitoring and study of cyclones. The balloons 71 move in the direction 72. According to a second application of a network according to the invention shown in FIG. 7, the network 100 is such that the nodes 102, 102 'collectors are fixed stations, for example at bottom of the sea, and knots 103; are associated with mobile capsules 74 in the water (marine environment) according to the dynamics of the aquatic environment in which they are immersed. The network 30 formed in this form is suitable for being applied for the observation of water currents.

According to a third application of a network according to the invention shown in FIG. 8, the network is such that the nodes 102, 102 'collectors are stationary stations on the terrestrial ground and the nodes 103; remain motionless at their drop point in a terrestrial soil environment to be monitored. The network formed in this form is suitable to be applied for example for monitoring fires, for example in a forest. The invention can be the subject of many alternative embodiments and applications other than those described above. In particular, the invention is advantageously applicable to networks in which the nodes (in any case at least a part of them) are mobile along indeterminate paths (random, ballistic, etc.), and are connected by links without wire, in particular radiofrequency, GSM telephone ... The management messages broadcast step by step from each collecting node according to a transmission that can be described as rising (as opposed to the transmission, which can be described as descending data messages) from the source nodes to the (x) node (s) collector (s)) allow to establish a topology of the network and to optimize the routing paths between the nodes. Furthermore, a network according to the invention may be provided with additional functionalities improving its operation, such as for example the fact that the processing module 88 of each node is adapted to send a PING type service message: - destined to a predetermined node (nearest node most recently identified in its memory 16), so as to verify that this node is still in range, and / or - at all nodes to identify the nodes that are in range. In this case, the processing module of each node is also adapted to respond to such a PING service message that it receives by returning to the sending node a service message of PONG type to validate the good reception of the message. PING service and returning the corresponding identification information and if necessary other information, such as its rank, the level of reception ... Such a PING / PONG protocol for wireless link validation is well known in itself. It can be implemented automatically by each node for example after a certain predetermined duration has elapsed without receiving a message. Likewise, preferably, the messages are transmitted in the form of serial frames with header and checksum, but any suitable transmission protocol or coding can be envisaged.

Claims (18)

REVENDICATIONS1. A method of communication between a plurality of electronic communication devices, called nodes, of a network (1), adapted to transmit messages (20) of data to at least one node, said node (102) collector, in which: - each node is adapted to be able to send and receive messages, - each node comprises a processing module (88) adapted to interpret and modify a received message, - a routing path between any one of the nodes and each collector node is determined by diffusion from near to near a message, said management message, sent by each node (102) collector, characterized in that: - each management message (19) comprises a digital field, said field (27) of rank, - the module (88) for processing a node receiving a management message (19) compares the value of the field (27) rank of the message with a digital value stored in a digital memory of the node, said 20 memory (12 ) of rank, - if the value contained in the rank memory (12) belongs to the set of indefinite values and values greater than the contents of the rank field (27), then the processing module (88) increments the content of the rank field (27), updates the contents of the rank memory (12) with the content of the incremented rank field (27), and retransmits the management message (19). 2.Procédé according to claim 1, characterized in that the module (88) for processing each node (102) collector is adapted to transmit a management message (19) containing a digital field, said field 30 (26) of session identifier, the value of which is modified according to a known order relation of the nodes. 3. Method according to claim 2, characterized in that the value contained in the memory (12) rank of a node is undefined when the processing module of the node receives a management message containing a numerical value whose field (26) session identifier contains a numerical value subsequent to that of the previous received management message (19). 4. Method according to one of claims 1 to 3, characterized in that each collecting node is adapted to include a collector node identifier in each new management message (19) that it initiates. 5. Method according to claim 4, characterized in that the module (88) for processing a node stores in a digital memory, said memory (25) collector node identifier, the node identifier of a node. collector whose management message (19) allows updating of its rank memory (12) with the smallest rank value. 6. Method according to one of claims 1 to 5, characterized in that each management message (19) comprises a digital field, said field (22) issuer node identifier, in which is recorded the node identifier of the node that issued this message last. 7. Method according to claim 6, characterized in that a node said receiving node (103;), having received a management message (19) for updating its memory (12) of rank, stores the value of the transmitting node identifier field of the message in a digital memory of the receiving node (103;), said closest node identifier memory, and replacing the contents of this field in this management message by the node identifier from the receiving node (103;), and then retransmits the management message. 8. Method according to one of claims 6 to 7, characterized in that each node comprises a device for measuring the signal level of reception of the message, and when a node (103;) receives a message (19) management whose rank field value is equal to that of the row memory (12), the processing module (88) is adapted to compare the level of the reception signal with that of the previous received message, and then store in the field transmitter node identifier, the node identifier providing the highest signal level. 9. Method according to one of claims 1 to 8, characterized in that each management message (19) contains a digital field, said field (23) of recipient identifier (s), containing at least one identifier of node of a destination node of the management message. 10. A method according to claim 7 and one of claims 1 to 9, characterized in that each transmitter node (103;) transmitting a data message (20) transmits it to the node whose identifier is node is stored in the node identifier memory closest to the transmitting node. 11. The communication method according to one of claims 1 to 10, characterized in that the reception by a node of a message (20) data triggers the sending by this node of a message, said message (21). of service, which constitutes an acknowledgment message if it accepts the data message, and a non-acknowledgment message if it refuses the data message. 12. Network (1) of electronic communication devices, called nodes, adapted to transmit messages (20) of data to at least one node, said node (102, 102 ') collector, wherein: - each node comprises a transmitter (5) and a receiver - each node comprises a processing module (88) adapted to interpret and modify a received message, - each collection node is adapted to send a message, said management message (19), distributed gradually by the nodes, characterized in that: - each management message (19) comprises a digital field, said field (27) of rank, - the module (88) for processing a node receiving a 30 management message (19) is adapted to compare the value of the field (27) of rank 41 of the message with a digital value stored in a digital memory of the node, said memory (12) of rank, - if the value contained in the memory (12) of rank belongs to the set formed of indepen- finite and higher than the rank field (27), then the processing module (88) is adapted to increment the value of the rank field (27), update the contents of the rank memory (12) with the content of the incremented rank field (27), and retransmitting the management message (19). 13. The network of claim 12, characterized in that it comprises a plurality of nodes, called source nodes, adapted to generate useful data to be transmitted, and in that the module (88) for processing each source node is adapted. to include this useful data in the messages (20) of data transmitted to each node (102, 102 ') collector. 14. Network according to one of claims 12 or 13, characterized in that the nodes (103;) are, at least partly, associated with structures (71, 74) movable and in that the nodes are connected together to others by wireless links. 15. Network according to claims 13 and 14, characterized in that said mobile structures are aerostats (71) placed in the Earth's atmosphere, and equipped with Earth observation means generating observation data as data. helpful. 16. Network according to claim 14, characterized in that the movable structures are placed in a liquid medium. 17. Network according to one of claims 12 to 14, characterized in that the nodes are associated with terminals capable of being worn by people. 18. Network according to one of claims 12 or 13, characterized in that the nodes are, at least partly, associated with fixed structures relative to the terrestrial ground. 30