FR2939268A1 - Communication path determining method for wireless radio communication network in home theater, involves determining path by selecting antenna orientation angle, in angular range, for which quality level value is greater than threshold - Google Patents

Abstract

The method involves determining an obstacle presence zone (700) by analyzing a communication quality between emitter and receiver devices (180, 140). Receiving quality level values are obtained by the receiver device receiving a signal emitted by the emitter device. A communication path is determined by selecting an antenna orientation angle, in angular observation ranges (709, 712), for which the quality level value is greater than a preset threshold. The obstacle determination, obtaining of level values and path determination are performed for establishing communication between the devices. Independent claims are also included for the following: (1) a computer program product comprising instructions for performing a method for determining a communication path in a wireless communication network (2) a storage medium comprising instructions for performing a method for determining a communication path in a wireless communication network (3) a device for determining a communication path in a wireless communication network, comprising a determination unit.

Description

Method for determining communication paths in a wireless communication network, computer program product, storage means and corresponding device FIELD OF THE INVENTION The field of the invention is that of communication networks, and more particularly of wireless communication networks with directional antennas. More specifically, the invention relates to a technique for detecting communication paths in a wireless communication network. The invention applies in particular, but not exclusively, in radio communication networks which may be subject to fading and / or masking of radio communications caused by obstacles. Throughout the present description, obstacle (or object) is understood to mean any physical element distinct from the transmitting and receiving devices of the network, included in the overall coverage area of the network and disturbing the wireless communication links. 2. BACKGROUND Traditionally, home wireless networks or PANs (for "Personal Area Networks") are intended to interconnect communication devices, such as, for example, digital devices, telephones, PDAs, speakers, television set, media player, located near the user. The range of such a communication network is of the order of a few meters. Such a network can also be used to communicate the different personal devices between them (what is more commonly called intra-personal communication), or to connect to applications supported by the Internet for example. Home networks can be wired (as is the case for networks such as USB, Ethernet, or according to IEEE 1394 standards) but can also be based on the use of a wireless medium. This is called home wireless network (or WPAN network for "Wireless Personal Area Networks" in English). Bluetooth (IEEE 802.15.1), UWB, ZigBee (IEEE 802.15.4), IEEE 802.1le or IEEE 802.15.3 standards are among the most used protocols for this type of network. Such protocols generally provide for two types of access to the shared wireless medium.

A first type of access is the collision detection mode (also called CSMA / CD for Carrier Sense Multiple Access / Collision Detection). This allows each device of the communication network to manage its emissions according to its needs and the availability of the medium. In the absence of information to be transmitted, the device receives data packets that circulate on the medium.

When this device needs to transmit one or more data packets, it verifies that no frame is transmitted on the medium. If so, he can issue his data packet. If it does not, it waits for the end of the current transmission. Since the access method is collision detection, when it is transmitted, a device can detect a contention problem, and stop to send back its data packet later, that is to say when it will have again the problem. word. In order to minimize the risk of encountering a second collision with the same device, each network device waits for a certain period (which may be random) before attempting a new transmission. However, in order not to saturate a network that would already be very busy in terms of communications, a network device does not attempt indefinitely to retransmit a packet of data if, at each attempt, it is in conflict with another network device. Thus, after a certain number of unsuccessful attempts, the data packet is deleted, thus avoiding the collapse of the network. The upper layers are then warned of the failure of the transmission of the message. A second type of access is a time division multiple access mode (also called TDMA mode, for Time Division Multiple Access). This second access mode is a multiplexing mode allowing the transmission of several signals on a single communication channel. This is the time multiplexing, the principle of which is to cut the available time in several time slots (also called time slots in English) or speech times which are assigned successively to the different devices of the network.

Such networks are conventionally based on the presence of a master device which is responsible for establishing network connections, synchronizing speech times of each of the network devices and arbitration of the network. access to the shared wireless medium.

Radio transmission systems currently use a wide range of transmission frequencies, typically between 2.5 GHz and 60 GHz. These frequencies are particularly well suited for very high speed data transmission in a limited radius, for example as a means of connectivity between the different elements of a home cinema type communication network. Indeed, for this use case, the range is limited to ten meters. On the other hand, the speeds involved are very high (beyond gigabit per second (Gbps or Gbit / s)) due to the nature (audio, video) and the very high resolution of the information transmitted. The use of transmit and receive antennas can also play a crucial role in the quality of communication for such wireless home networks.

An isotropic antenna, that is to say a radiating antenna with the same physical characteristics in all directions of space, is a theoretical model unachievable in practice. Indeed, the energy radiated by an antenna is actually distributed unequally in space, some directions being preferred. We then speak of radiation lobes. A radiation pattern of an antenna makes it possible to visualize these lobes of radiation in the three directions of space, that is to say in the horizontal plane or in the vertical plane including the most important lobe. The proximity and conductivity of the ground or conductive masses surrounding the antenna may further have a significant influence on the radiation pattern. The directivity of an antenna in the horizontal plane is an important feature in the choice of an antenna. In fact, an omnidirectional antenna radiates in the same way in all directions of the horizontal plane, whereas a directional antenna, for its part, has one or two lobes much larger than the others; we then speak of main lobes. It should be noted that an antenna is all the more directive as the largest lobe is narrow. The directivity is the width of the main lobe, between the 3 dB attenuation angles. The gain of an antenna is then defined as the increase of power emitted or received in the main lobe with respect to an omnidirectional antenna. A signal processing based on antenna directivity (called beamforming in English) is a technique based on the use of transmission boards or reception sensors that control the orientation and / or sensitivity of an antenna as a function of the antenna. a radiation pattern. When receiving a radio signal, this technique increases the sensitivity of the receiver device in a desired direction and thus reduce the sensitivity of the antenna for interference or highly noisy areas. When transmitting a radio signal, the antenna directivity technique makes it possible to increase the power of the radio signal in a desired direction. Such communication systems, although advantageous from the point of view of their installation and particularly high application rates (authorized for high frequencies such as the 60 GHz frequency band for example), however, have a high sensitivity to the phenomena of interference and masking of radio links caused by obstacles. Thus, the relevance as regards the use of the communication paths (also called routing paths) between the different devices of the network is strongly correlated with the positioning and the displacement of obstacles in the network, which are as many sources of masking phenomena. dynamic for the network. Thus, given the particularly random nature of this type of communication medium, a method of multiple transmissions of data symbols transmitted on the network can be particularly effective to ensure good reception beyond a rate of predefined residual error. This method is particularly suitable for applications requiring little bandwidth (of the order of ten Mbps (for Mega bits per second), such as audio data transmission or control data. the bandwidth of the network generally limited for such home wireless networks, the previous method of multiple transmissions is unsuitable for applications requiring a higher data rate (of the order of a hundred Mbps), video applications, for example, it is more interesting to consider only a single transmission of data symbols on the network and to implement an adaptive routing method for sensitive communications. disturbances of the network, according to the actual position of moving obstacles in the network coverage area. e alternative (or additional) communication can then be considered, the network devices adapting the choice of paths actually used to instantaneous disturbances of the network. In addition, it is possible that a given obstacle masks completely the path in direct connection between two devices, which requires finding an indirect path to establish communication between the two devices. Such communication paths can be established in direct link (we speak then of line of sight or LOS (for Line Of Sight in English), or in indirect link (we speak then of paths in non-line of sight or NLOS ( the second case, the routing of data between the transmitter and receiver devices of the network, via a communication path, involves a relay device, the latter can be active, that is to say implementing a data relay in accordance with a predefined transmission protocol (allowing a relay, performed by a device of the communication network, deferred from the data received), or passive, c that is, implementing a relay of the data by reflection of the data transmitted by the transmitting device The devices functioning as active relay of the network are generally known to all the other network devices. These are in fact network devices having a particular data relay functionality. Passive relays, meanwhile, are not necessarily known devices network. This type of relay, in fact, has no means of communication with the other devices of the network, because it does not have transmit antennas or reception. It can be a wall or an object with reflective capabilities, such as a plate or metal bar for example. Thus, in order to reinforce the robustness of data exchanges on the network using a single transmission mode, it can therefore be particularly interesting to discover the greatest possible number of alternative communication paths of the network, making intervene passive relays (or passive reflectors) to allow more flexibility in data routing. A conventional method, for those skilled in the art, of discovering communication paths, involving passive relays, would be to scan (or scan) the coverage area exhaustively using the antennas of the transmitter and receiver devices. involved in a given data communication. Such a method nevertheless has the disadvantage of having a particularly high processing time, requiring a significant interruption of the operating mode in network communication.

The international patent application WO200795354, filed by the company SiBEAM, addresses the issue of the adjustment of antennas in transmission and reception to obtain the best quality of communication for a pair of transmitter and receiver devices. This method relies on the implementation of successive learning sequences by varying the characteristics of transmit and receive antennas before finding an optimal antenna configuration. However, such a method also requires a significant processing time, because of the different antenna configurations to be tested. OBJECTIVES OF THE INVENTION The invention, in at least one embodiment, has the particular objective of overcoming these various disadvantages of the state of the art. More specifically, in at least one embodiment of the invention, one objective is to provide a technique for determining additional communication paths between a transmitting device and a receiving device in a wireless communication network.

At least one embodiment of the invention also aims to provide such a technique which relies on an identification of potential passive relays, distinct from the devices of the network, making it possible to determine the existence of communication paths, between a transmitting device and a receiver device, involving one of the previously identified passive relays.

Another objective of at least one embodiment of the invention is to provide such a technique requiring a short processing time to determine the existence of additional communication paths between a transmitting device and a receiving device, in order to limit the interruptions in the context of the exchange of useful data in the network or to speed up the communication between the transmitting device and the receiving device.

Yet another object of at least one embodiment of the invention is to provide such a technique that does not require exhaustive scanning of the antenna coverage area of the transmitting device and / or receiver device to determine existence of communication paths. A complementary objective of at least one embodiment of the invention is to provide such a technique which relies solely on means conventionally used for the transmission of data within a wireless communication network. In other words, the present invention aims to provide a technique that is simple to implement and inexpensive. SUMMARY OF THE INVENTION In a particular embodiment of the invention, there is provided a method for determining at least one communication path in a wireless communication network comprising a set of pairs consisting of a transmitter device and receiver device. Such a method comprises the steps of, for a communication to be established between a transmitting device and a receiving device: - determining an obstacle presence zone by communication quality analysis between devices of said pairs; obtaining reception quality level values, by the receiving device (140) of a given signal transmitted by the transmitting device (180), by scanning, receiving and / or transmitting, at least a part of an angular range of sight, an angular range of sight being representative of a set of antenna orientation angles oriented according to the determined obstacle presence area; determining at least one communication path, by selecting an antenna orientation angle, in the angular aiming range, for which the received reception quality level value is greater than a predetermined threshold.

The general principle of the invention consists of a method of discovering the existence of communication paths involving a passive relay considered, by simple analysis of the communication quality level of a pair of transmitter and receiver devices. To do this, various antenna angular positions, belonging to an angular range of sight defined according to a geographical area of the network, in which a potential passive relay is located, are tested in order to determine if a communication can be established (with a level of sufficient quality) between the devices of the pair of transmitter and receiver devices. The invention advantageously provides for restricting the geographical area to be tested during the communication path discovery process, by limiting the angular range of sighting to the obstacle presence zone. This therefore results in a significant gain in terms of processing time compared to methods known to those skilled in the art relating to the exhaustive scanning of the antenna coverage area of the transmitter and receiver devices involved in a communication.

The invention is therefore based on a completely new and inventive approach of identifying network obstacles, a priori disruptive communications, each of which can play the role of a relay of a communication of a pair of transmitter and receiver devices , and therefore can contribute to an optimized routing of network communications.

Advantageously, said obstacle presence zone is determined by mutual overlap of at least two intersection zones of communication coverage areas of a pair of transmitter and receiver devices, each of them having a state of disturbance. according to a determined criterion of communication quality between the devices of a pair of transmitter and receiver devices.

In this way, they are transmission characteristics related to communications between network devices (that is, the state of disruption of each of the intersection areas of device pair coverage areas) that allow a summary of these one-off results to arrive at a consolidated estimate of locations of objects (or obstacles) in the network's coverage area.

Advantageously, the method comprises a step of checking whether an obstacle, present in the obstacle presence zone, is fixed, by analyzing a state of disturbance of said obstacle presence zone for a predetermined duration and said step of obtaining reception quality level values is performed in case of positive verification. Thus, among the disturbing obstacles, only the fixed obstacles that can be effectively exploited as passive relays are considered. Such discrimination of mobile obstacles is explained by the fact that a mobile obstacle requires a treatment that is too complex as to the calculation of its position in the network and leads to a guarantee of too random exploitation of its possible thinking abilities, in order to use it effectively as a passive relay. Preferably, in said step of obtaining reception quality level values, the angular range of view is determined so that it defines, for a receiving device or an associated transmitting device, a scanned coverage area whose ends are defined by edges or end vertices of the obstacle presence zone. Thus, only the relevant angular positions of the transmitting and / or receiving antennas, that is to say those likely to be associated with a communication path, are tested.

In another embodiment, the invention relates to a computer program product downloadable from a communication network and / or recorded on a computer readable medium and / or executable by a processor. This computer program product includes program code instructions for carrying out the aforesaid method (in any one of its various embodiments), when said program is run on a computer. In another embodiment, the invention relates to a computer readable storage means, possibly totally or partially removable, storing a computer program comprising a set of instructions executable by a computer to implement the aforementioned method (in any of its different embodiments).

In another embodiment, the invention relates to a device for determining at least one communication path in a wireless communication network comprising a set of pairs consisting of a transmitting device and a receiving device. A determination device comprises, for a communication to be established between a transmitting device and a receiving device: first means for determining an obstacle presence zone by communication quality analysis between devices of said pairs; means for obtaining reception quality level values, by the receiver device (140) of a given signal transmitted by the transmitting device (180), by scanning, on reception and / or on transmission, of at least part of an angular aiming range, an angular aiming range being representative of a set of antenna orientation angles oriented according to the determined obstacle presence area; second means for determining at least one communication path, by selecting an antenna orientation angle, in the angular aiming range, for which the reception quality level value obtained is greater than one predetermined threshold. Advantageously, said obstacle presence zone is determined by mutual overlap of at least two intersection zones of communication coverage areas of a pair of transmitter and receiver devices, each of them having a state of disturbance. according to a determined criterion of communication quality between the devices of a pair of transmitter and receiver devices. Advantageously, the determination device comprises means for verifying that an obstacle, present in the obstacle presence zone, is fixedly determined by analyzing a state of disturbance of said obstacle presence zone for a predetermined duration. said means for obtaining reception quality level values being activated in case of positive verification. According to an advantageous characteristic, the angular aiming range is determined so that it defines, for a receiving device or an associated emitter device, a swept area of coverage whose ends are defined by edges or end vertices of the obstacle presence area. 5. LIST OF FIGURES Other features and advantages of the invention will appear on reading the following description, given by way of indicative and nonlimiting example, and the appended drawings, in which: FIG. 1 illustrates an example a wireless communication network in which can be implemented the method of determining communication paths, according to a particular embodiment according to the invention; FIG. 2 shows an example of a synchronous physical layer using time division multiplexing (TDM); FIG. 3 shows the schematic structure of a communication device of the communication network implementing the method for determining transmission paths according to a particular embodiment in accordance with the invention; FIG. 4 illustrates a schematic example of a coverage intersection zone obtained for a pair of transmitting and receiving devices of a communication network according to a particular embodiment of the invention. FIG. 5a schematically illustrates an example of an overlap zone in a wireless communication network according to one particular embodiment of the invention; FIG. 5b presents a flowchart of an algorithm for locating areas of presence of objects according to a particular embodiment of the invention; - Figure 6 schematically illustrates a communication between a pair of transmitter and receiver devices, according to a selective data transmission mode; - Figure 7 schematically illustrates a method for determining an angular range of sight, for a potential passive relay, according to a particular embodiment of the invention; FIG. 8 represents a flowchart of an algorithm for implementing the method of determining communication paths in a wireless communication network, according to a particular embodiment of the invention; FIG. 9 illustrates a communication path discovery protocol, according to a first particular embodiment of the invention; FIG. 10 illustrates a communication path discovery protocol, according to a second particular embodiment of the invention; FIG. 11 represents a flowchart of a communication path detection algorithm for a receiver device in a wireless communication network, according to a particular embodiment of the invention; FIG. 12 describes the structure of a communication path discovery request message, as described in FIG. 9; FIG. 13 illustrates the structure of a discovery request acknowledgment message, as described in FIG. 9; FIG. 14 illustrates the structure of a scan initialization message of an angular sighting range in reception, as described in FIG. 9; FIG. 15 illustrates the structure of a communication path discovery report message, as shown in FIGS. 9 and 10; FIG. 16 illustrates the structure of a communication path discovery end notification message for a potential passive relay of the network, as shown in FIG. 9; FIG. 17 illustrates the structure of a communication path discovery report acknowledgment message as shown in FIG. 10; FIG. 18 represents a flow diagram of an algorithm for selecting a communication path for a pair of transmitter and receiver devices, according to a particular embodiment in accordance with the invention; FIG. 19 illustrates the format of a selection message for a communication path, as shown in FIG. 18; FIG. 20 illustrates the format of a selection message of a communication path as shown in FIG. 18. DETAILED DESCRIPTION In all the figures of this document, the elements and identical steps are shown in FIG. designated by the same numerical reference. FIG. 1 shows an example of a wireless communication network 100 in which the method for determining communication paths can be implemented, according to a particular embodiment in accordance with FIG. the invention.

More particularly, the network 100 of FIG. 1 illustrates a wireless 7.1 audio communication system, of the home theater type for example, comprising a source device 112 having two transmission antennas 110 and 111, as well as a plurality of devices. transmitters and receivers 120, 130, 140, 150, 160, 170, 180 and 190, each device being able to behave alternately as a transmitting device and a receiving device and having only one antenna for transmitting and receiving radio data. In addition, some nodes can play the role of relay node, that is to say that they retransmit on the network data they have previously received from another node. The network devices are all interconnected by radio communication links 101. Although the radio signals can be broadcast in all directions, some relay nodes or receivers may not be able to detect these radio signals due to the presence of radio signals. 'obstacles. A radio link is not necessarily present between a transmitting device and any other receiving device of the network. It should be noted that the description which follows illustrates a particular embodiment of the invention, certain starting hypotheses to be taken into consideration. Indeed, the topology of the communication network 100, that is to say the relative spatial position of the devices 120, 130, 140, 150, 160, 170, 180 and 190, is considered as being known from each of the devices 120 130, 140, 150, 160, 170, 180 and 190 of the network 100. The topology of the network 100 can be effectively known in advance by each of the devices 120, 130, 140, 150, 160, 170, 180 and 190 since a predefined network 100 installation is required for certain configuration recommendations as recommended by a standard (such as for example the ITU-R BS.775-2 standard adapted for a 7.1 type audio system) or because of the capacity of the network devices 120, 130, 140, 150, 160, 170, 180 and 190 to calculate their distances and relative angles to each of the other devices of the network 100.

In the remainder of the present description, it is therefore considered that the topological knowledge of the network 100 by each of the devices 120, 130, 140, 150, 160, 170, 180 and 190 included in this network 100 is induced by the normalization of the network. installation of the communication network 100.

In addition, the particular embodiment described below, intended for communication networks of home theater type, is given by way of illustrative example. It is clear that many other embodiments of the invention can be envisaged, without departing from the scope of the invention. When transmitting radio data, the data stream consists of a plurality of data blocks and is conventionally protected against transmission errors by means of error correction code. Typically, the data stream data blocks are packaged together at a sender device, each packet being encoded to generate a plurality of parity blocks representing redundant information. A receiving device of the network 100, receiving the data packets, via the various radio communication links, then proceeds to the decoding. This decoding step consists of removing the errors in the data blocks received by the receiving device by using the parity blocks for this purpose. The relay devices, meanwhile, perform the transfer of coded data packets as such, without decoding or re-encode the data stream. Indeed, it is important to note that the performance of the decoding and subsequent coding at each relay node would exhaust the memory consumption required for temporary storage of the packets, and would also increase the delay of transmission while consuming resources unnecessarily. Calculation.

In addition, to transmit a stream of data relating to an audio stream, a video stream or a combination of both, a protocol such as that described by the IEEE 802.15.3 standard can, for example, be implemented. In addition to the fact that it allows very high data rates (in its 802.15.3c version), because of data transmission in the 57-64 GHz frequency band, this protocol offers the possibility, for each of the network devices, to gain access time to the guaranteed shared wireless communication medium by using time division multiplexing, also called TDM (for Time Division Multiplexing), providing division of the time domain into a plurality of intervals recurring time, fixed length, also called TDM sequence or cycle. Such multiplexing allows certain parameters, such as latency or data rate, to remain invariant.

Referring now to FIG. 2, an example of a synchronous physical layer using time division multiplexing (TDM) is illustrated. Conventionally, in this data transmission mode, the time is divided into cycles 210, called TDM sequences and the physical medium shared in time so that each of the devices of the communication network is allocated at least one talk time. by cycle 210 for transmitting data 230 (data generated by the device itself or an application connected thereto, or relayed data). Each speech time 220 can carry zero, one or more data blocks of a data stream, depending on the flow rate of this data stream, and more generally, depending on the data actually to be transmitted. Thus, each of these data blocks also corresponds to a time transmission interval. It may be noted that among the blocks of data, whether clean or relayed, there are blocks of control data, allowing the transmission and relaying of control messages (such as those described later in relation to FIGS. 12 to 17, 19 and 20).

Each data block can itself be divided into a plurality of packets or symbols. The relay devices of the communication network also retransmit data blocks (relayed blocks) to third-party devices (or nodes) of the network so that, at the end of the cycle (or a predetermined number of cycles) , all the devices can receive these data blocks. This is called Network Mesh Relay. The transmission of control messages and low bit rate data streams (relative to the capacity of the communication network) is in a quasi-omnidirectional transmit antenna pattern. This makes it possible to increase the probability that the data will be received by devices of the network (which can then relay this data so that all the devices of the network can eventually receive this data). Certain communications, including high-speed data streams (relative to the capacity of the communication network) or for which any network-link relay would be impossible or excessively bandwidth-intensive, do not require active relaying through a device of the communication network. Thus, in the TDM sequence, time slots are allocated to the transmission according to a first transmission mode (quasi-omnidirectional antenna configuration) and time slots are assigned to the transmission according to a second transmission mode ( selective antenna configuration). The use of these different transmission antenna configurations will be further described later. FIG. 3 shows the schematic structure of a communication device 300 of the communication network 100 implementing the method for determining transmission paths according to a particular embodiment in accordance with the invention. More specifically, the communication device 300 is integrated in each of the sending devices or receiving devices (120, 130, 140, 150, 160, 170, 180), or in any relay device of the communication network 100.

The communication device 300 comprises: a Random Access Memory (RAM) 302 functioning as a main memory; a calculation block 301 (noted ptc for micro-controller in English) or CPU (for Control Process Unit in English) whose capacity can be extended by an optional RAM connected to an expansion port (not shown on FIG. Figure 2). The CPU 301 is capable of executing instructions when the communication device 300 is turned on from the ROM 303. After the power is turned on, the CPU 301 is able to execute the RAM 302 relating to a computer program, once these instructions loaded from the ROM 303 or external memory (not shown in Figure 3). Such a computer program, if executed by the CPU 301, causes the execution of some or all of the steps of the algorithms described hereinafter with reference to FIGS. 8, 11 and 18; a block 305 (denoted RF-FE for RF Front-End in English) responsible for adapting the signal at the output of a baseband block 306 (denoted RF-BB for RF Base-Band in English) before its transmission by means of an antenna 304. By way of example, the adaptation can be carried out by frequency conversion and power amplification processes. Conversely, the block 305 also allows the adaptation of a signal received by the antenna 304 before its transmission to the baseband block 306. The baseband block 306 is responsible for modulating and demodulating the digital data exchanged with the baseband 306. block 305; an input / output interface block (denoted I / O I / f for Input / Output Interface in English) 311 connected to a communication network 312.

With reference to FIG. 4, a schematic example of a roof intersection zone 401 obtained for a couple of transmitter / receiver devices 130, 120 communicating in a communication network according to a particular embodiment of the invention is presented. 'invention. More particularly, the communication network is a wireless communication network, of the home theater type, comprising a source device 112 comprising two transmission antennas 110 and 111, as well as a plurality of transmitting or receiving devices 120, 130, 140 , 150, 160, 170, 180 and 190, each of the devices being able to play the role of relay device (whose principle is recalled above in relation to FIG. 1).

The device 130 of the network is now considered as a transmitting device emitting with an emission radiation angle of 180 °, that is to say covering the entire network, and the device 120 as the associated receiver device. The transmitting device 130 has a quasi-omnidirectional antenna (relative to the extent of the communication network), whose associated coverage area (not shown in the figure) is estimated as that produced by an angle of 180 ° between the axes ( x'o 404, xl 402) and (x'o 404, x2 403). The receiving device 120 has a directional antenna whose main selectivity lobe is represented by the coverage area 401 of its receiving antenna corresponding to the space between the axes (xo 400, xl 402) and (xo 400, x2 403). The coordinates of the vertices xo 400, xl 402 and x2 403 are defined in a predefined reference 471, depending on the configuration of the communication network.

In the case where the communication network is used in a home cinema sound system, the configuration can be predefined at the factory manufacture, or be provided by a user at the initialization of the system, which allows this last to be able to select a configuration adapted to its environment. In any case, the configuration of the devices is previously defined and a common location mark is used by the devices of the network. The location marker used is known to each of the network devices, as is the topology of the network. Thus, the receiver device 120 is responsive to (i.e. can estimate) any power loss of the signal transmitted by the transmitting device 130, detected in the reception coverage area 401. For the sake of clarity in the following from the description, a reception coverage area will be assimilated to a coverage intersection area for a pair of transmitter and receiver devices. In reality, an intersection zone is an intersection between a transmission coverage area and a reception coverage area.

This area of intersection of covers 401 (obtained by considering that the angle between the axes (x'o 404, xl 402) and (x'o 404, x2 403) is 180 °) also allows an indeterminate positioning of the transmitter device 330 around a normalized position, provided that it remains between the points xl 402 and x2 403, allowing the receiver device 120 to possibly detect a loss of power of the signal emitted by the transmitting device 130. alternative embodiment consists in defining a transmission coverage area with an angle between the axes (x'o 404, xl 402) and (x'o 404, x2 403) lower than 180 ° (if it were higher, this would be equivalent to consider it at 180 °). This angle is defined by the transmitting antennas of the communication devices of the network and is substantially the same for all the devices of the network. It is the same for the radiation angles in reception. Each device then has the knowledge. In the opposite case, it is possible for the person skilled in the art to provide a protocol for exchanging configuration data that can be implemented between all the devices of the network so as to exchange the angle values relating to the zones. antenna coverage in transmission and / or reception.

In sum, by detecting a power loss of the signal received from a transmitter device of the network, the power of the signal being measured and compared to a theoretical power vacuum, that is to say in ideal conditions transmission (without obstacle or disturbance), a receiving device of the network is able to detect the presence of an obstacle, or a disturbing object in the intersection area of covers 401 relative to the transmitting device. In the following, a coverage intersection area at which a power loss is detected will be designated as a disturbed area. In a particular embodiment, each of the devices of the network performs a measurement of the power of the radio signal for each of the intersection zones of covers relating to each of the transmitting devices of the network and then transmits the result of these measurements to a central device the network, which in turn must communicate the result of the analysis of the disturbances of the overlapping areas to the other devices of the network. A central device (or control device) is understood to mean a device of the network implementing centralized management of the algorithms for analyzing the disturbances of the recovery zones. In an alternative embodiment, the method of analyzing the overlapping zone disturbances being deterministic, it can be implemented by a set of devices of the network, independently of each other. It is only necessary for the set of devices to receive the perturbation status information relating to the intersection areas of covers from the other devices in the network. The analysis of the disturbances of the zones of overlap is carried out by correlation of the power measurements in order to determine the presence or not of disturbed overlapping zones, an overlap zone being an intersection of at least two intersection zones of covers. An exemplary overlap zone is illustrated below in relation to FIG. 5a. FIG. 5a illustrates an example of a covering zone 575 in a wireless communication network according to one particular embodiment of the invention. In a similar manner to FIGS. 1 and 4, it is considered that the communication system of FIG. 1 is a wireless home-cinema-type wireless communications network 100 comprising a source device 112 for audio and / or video content having two transmission antennas 110 and 111, as well as a plurality of transmitting or receiving devices 120, 130, 140, 150, 160, 170, 180 and 190, which can act as a relay device (according to the principle stated above in connection with Figure 1). In the present case, we consider two intersection zones of covers 541 and 561 relating to the two emitter and receiver pairs respectively 180/140 and 130/120. The coordinates of the vertices xl 571, x2 572, x3 573 and x4 574 of the overlap zone 575 of the intersection areas of the covers 541 and 561 are determined. If the intersection areas of the covers 541 and 561 each have a level of a strong disturbance, the overlap zone 575 can then correspond to an area in which an object (or obstacle) is positioned, which is disturbing for the communications of the two intersection zones of covers 541 and 561. It is therefore possible to refine the size determination of the overlap area 575 by considering the intersection of the lap coverage area 575 with at least one other disturbed area of the network, in the case where such another disturbed area exists. For this purpose, it is possible, for example, to use a Weiler-Atherton polygon clipping algorithm. FIG. 5b presents a flowchart of a presence zone localization algorithm. objects according to a particular embodiment of the invention.

Each receiving device of the network can determine the quality level of link (or communication) it has with a transmitting device, when the latter transmits a signal with an omnidirectional antenna configuration, and transmit them to the other devices of the network via the blocks. of control data already mentioned in connection with FIG.

Once the information pertaining to the state of disturbance of the intersection areas of network covers collected, as transmitted by the receiving devices of the network, it is possible to implement the location algorithm in order to locate the zones of presence of the network. at least one object (or obstacle) in the coverage area of the network, this object (or obstacle) causing disturbances within the network. In such a case, the algorithm makes it possible to define the position, relative to the devices of the network, of a polygonal zone within which the object or obstacle is located. In a first step 5000, the set of network coverage intersection zones is sorted according to their respective disturbance state, as received from the receiving devices of the network. Then, in a step 5001, a list comprising all the disturbed areas (called the perturbation list) and then a list comprising all the undisturbed zones (called the non-disturbance list) in a step 5002 is established. In a step 5003 of the algorithm, the central device of the network then performs, for each intersection area of covers present in the disturbance list, a polygonal intersection correlation with all the other intersection areas of covers present. in the perturbation list, in accordance with the mechanisms previously mentioned in connection with FIG. 5a. The set of polygonal intersection overlapping zones thus obtained is then stored in a list of overlapping zones, during a step 5004. In a step 5005 of the algorithm, then, for each recovery zone stored in the list of overlapping zones, a polygonal subtraction correlation with the set of non disturbance zones present in the non disturbance list. Such a polygonal subtraction correlation can for example be implemented by means of a half-line algorithm (or half-line algorithm, in English), known to those skilled in the art. The set of polygon subtraction overlapping zones thus obtained, corresponding to the zones of presence of disturbing objects (hereinafter also referred to as location zones), is then stored in a location list, during the step 5006 of the present algorithm. Each location area of the location list thus updated corresponds then to the relative positioning of disturbing objects of the network with respect to the transmitter, receiver or relay devices devices of the network.

The obstacle (or object) is detected, in application of the algorithm described above in connection with FIG. 5b, as being present in a covering zone or a set of overlapping zones, possibly reduced by one or more area (s) of recovery. For the sake of simplicity, it will be possible to assimilate the zone of presence of a detected obstacle to a zone of overlap. Figure 6 schematically illustrates a communication between a pair of transmitter and receiver devices, according to a selective data transmission mode (or beam steering in English). A wireless communication system, such as that described in FIG. 1, is considered in which the device 140 is considered as a receiver device for the transmission of data coming from the transmitting device 180. The transmitting device 180 uses, in the In this case, an antenna directivity technique (called beamforming in English) to reduce the angle of radiation of its transmitting antenna, in order to increase the power of the signal in the desired direction. The emission radiation 601 obtained is thus selective (due to the low radiation angle of emission) and directed towards the receiver device 140. The receiver device 140 also uses the antenna directivity technique to reduce the radiation angle of its antenna in reception. The reception radiation 600 obtained is therefore selective and directed towards the transmitting device 180. FIG. 7 schematically illustrating a method for determining an angular range of sight, for a potential passive relay, according to a particular embodiment of FIG. the invention. In order to determine an additional communication path, involving a passive relay, an angular aiming range is determined, at least for the receiver device 140 of a pair of transmitter devices 180 / receiver 140 considered. In a particular embodiment, the transmitter device 180 and the receiver device 140 both calculate an angular range of sight for a potential passive relay previously detected. In a particular variant embodiment, only the receiver device 140 determines an angular range of sight for a previously detected potential reflector.

Such an angular range of sight allows the transmitting device and / or the receiving device to limit the geographical area of potential communication path search of the network by restricting it to the geographical area 700, corresponding to a recovery zone in which a has been detected an obstacle (according to the principle detailed above in relation to Figures 4, 5a and 5b). Indeed, this obstacle being determined by the fixed state of disruption of the overlap area for a certain period of time and having reflection characteristics, it can be tested as a potential passive relay. Consider again a wireless communication system, such as that described in Figure 1, wherein the emitter devices 180 and receiver 140 are able to communicate.

Subsequently, only a calculation method for the angular aiming range 712, delimited by the lines 710 and 711 relative to the receiving device 140, is detailed. It is clear, however, that this method can be applied, identically, for the calculation of the angular aiming range 709 delimited by the lines 707 and 708 and relating to the emitter device 180.

We recall that the general equation of a line, in an orthonormal frame, is generally written in the form y = mx + b where m denotes the slope of the line and b denotes its ordinate at the origin. Knowing two points of a line defined by their coordinates (xl, yl) and (x2, y2), it is then possible to determine the values of m and b. Thus, m is (y2 û yl) / (x2 û xl) and b is deduced from the equation y = mx + b.

We now consider two line segments of equations y = mlx + b1 and y = m2x + b2. The coordinates of the point of intersection of these two lines then satisfy the relation: y = mlx + b1 = m2x + b2, ie (ml-m2) x = b2-b1 and finally x = (b2-b1) / (ml- m2). The values of b1 and b2 are then deduced from the equations y = mlx + b1 and y = m2x + b2.

It should be noted that if ml = m2, the two lines considered are parallel and therefore have no point of intersection. Once the point of intersection, if existing, calculated, it remains only to determine if it belongs to each of the two segments considered. In other words, for each of the two segments considered, it should be verified that the abscissa value of the calculated intersection point is greater than the smallest abscissa value of the segment (i.e. at one end) and less than the largest abscissa value of the segment (i.e., the second end). We now consider the calculation of the angular range of sight 712 delimited by the lines 710 and 711 relative to the receiving device 740, assimilated in the reference 713 at the point x, 714. The algorithm for implementing the calculation of such aiming range may comprise the following steps, for the determined overlap zone 700: determination of the segments making up the overlap zone 700, that is to say the segments (si) which join the vertices of the overlap zone 700 , namely: if = [X1, X2], S2 = [X2, X3], S3 = [X3, X4], S4 = [X4, X5], S5 = [x5, X6] and S6 = [X6, X1] ]; - scanning of the ends of the segments s; beginning with the ends of the smallest abscissa value: a) for each end xi, checking for the existence of an intersection between the segment [x ,, xi] and at least one of the segments s; ; b) if such an intersection exists, reiteration of step a) with the end xj + 1 c) if such an intersection does not exist, the line (xi, X7) is considered as a limit of the angular range of target for geographical area 700 determined. This limit can therefore correspond to a single point xi or to a segment (edge of overlap zone) of the contour of the overlap zone. In the latter case, the straight line (xi, X7) coincides with a segment of the contour of the overlap zone. At the end of these steps, it is thus determined that the lines (x ,, x2) 710 and (x ,, x5) 711 are the limits of the angular aiming range 712 of the receiving device 140 relating to the overlap area 700 A flow diagram of an algorithm for implementing the method for determining communication paths in a wireless communication network according to a particular embodiment of the invention is now presented, in relation to FIG. In a step 800, the network devices determine the disturbing obstacles of the network, according to a method whose principle is described above in connection with Figures 4, 5a and 5b. It should be noted that this method, being implemented in the context of a TDM type of communication mode (according to the principle of FIG. 2), it does not require any interruption of data transmissions in the network. The network devices also differentiate the fixed obstacles of the mobile obstacles present in the coverage area of the network, so as to retain only the fixed obstacles as potential passive relays. To distinguish a moving object (or obstacle) from a fixed obstacle, the stability (or the constancy) of the disturbances of the overlap zone where the object (or the obstacle) has been detected for a predetermined duration is checked. If the disturbances are constant within a given range (that is, subject to variations, around a nominal value, negligible in relation to this nominal value), during the predetermined duration, it can be deduced that the object is fixed, and that it is a potential passive relay. If the disturbances vary beyond the given interval for the predetermined duration, it can be deduced that the object is mobile, and that it is not a potential passive relay. In a step 801, the transmitter and receiver devices in a particular embodiment (described below with reference to FIG. 9), or a receiver device only in an alternative embodiment (described below in connection with FIG. 10 ), select (s) a potential passive network relay from among the fixed obstacles present in the coverage area of the network and detected in step 800 of the present algorithm. In a step 802, the transmitter and receiver devices determine an angular range of sight for the overlap zone associated with the potential passive relay considered.

Then, in a step 803, the transmitter and receiver devices determine the existence of a communication path involving the potential passive relay considered and validate the angular configuration of the transmit and receive antennas in a step 804. The steps 801 to 804 are then reiterated until the set of potential passive relays determined in step 800 of the present algorithm has been tested. The algorithm then makes a transition in the end state 805.

It should be noted that the implementation of steps 803 and 804, in contrast to the implementation of step 800, may require an interruption of data communications network. This interruption of the communications is however only penalizing, since the present algorithm can be implemented, in a particular embodiment, during a step of initialization of the system, then only with each discovery of a new relay potential liability in the network, or the establishment of a point-to-point communication (i.e. low radiation angle) between the transmitter and receiver devices considered. FIG. 9 illustrates a communication path discovery protocol, according to a first particular embodiment of the invention. More precisely, FIG. 9 describes a communication path discovery protocol in which a pair of transmitting and receiving devices considered perform an antenna angle sweep (also called an angle of view). A transmitter device 900 and a receiver device 901 seek to determine a communication path that uses the selective data transmission mode, as described in FIG. 6. The two transmitter devices 900 and receiver 901 perform, at first, network obstacle detection (Network_Scan () functions 902 and 903) in which they determine the geographical areas of the network, i.e. the recovery areas, relating to the location of fixed obstacles. In addition, during this detection phase, they calculate the angular aiming ranges relative to each of the fixed obstacles, considered as potential passive relays. The transmitter device 900 then initiates a communication path discovery phase, for a potential passive relay of the network, by transmitting a request for discovery of communication paths, called Discovery_req 904 (the structure of which is detailed in FIG. 12). At the initiation of the communication path discovery phase, the transmitter device 900 transmits, during time intervals of the TDM sequence dedicated to the passive relay communication path search, a signal of predetermined characteristics known to the receiving device. 901. During the communication path discovery phase, the receiving device 901 must scan a defined geographical area according to the overlap zone in which the object (or obstacle) has been detected, for the purpose of receiving said signal of predetermined characteristics transmitted by the transmitter device 900. The receiver device 901, if it has also discovered, during the implementation of the Network_Scan () function 902, the potential passive relay specified in the request Discovery_req 904, acknowledges the request 904 by issuing a protocol message Discovery_req_grant 905 to the device 900 (whose structure is Figure 13). It is clear that the protocol messages described in connection with FIG. 9 are not transmitted according to a selective data transmission mode between a transmitting device and a receiving device, but according to the transmission mode with a quasi-omnidirectional transmission antenna ( as described in connection with FIG. 4) allowing messages to be relayed via the mesh of the communication network. If the sending device 900 has not received the message Discovery_req_grant 905 at the end of a time period T_grant 906, from the transmission of the request Discovery_req 904, it abandons the process of discovery of communication paths for the potential passive relay specified in the request Discovery_req 904. On receiving a Discovery_req_grant message 905 from the receiving device 901, the transmitting device 900 then initiates a scanning phase of its angular range of view by calculating a first value angular orientation of its antenna transmission (function Tx_Adjust () 907). On subsequent implementations of the Tx_Adjust () function 907, the transmitter device 900 thus calculates the angular value by increasing the current value of the value corresponding to a predefined step, such as for example 1 degree. Once the calculated angular value, the transmitter device 900 initiates the scanning process in reception of the angular range of sight by emitting the Sweep_Init message 908 (the structure of which is detailed later in FIG. 14), relative to the angular value of orientation of its transmitting antenna resulting from the implementation of the function Tx_Adjust () 907.

On receipt of the Sweep_Init message 908, the receiving device 901 then performs, for the potential passive network relay specified in the Discovery_req request 904, a scan of the associated receive angular range in order to determine the existence, or the absence of communication path (s) involving the potential passive relay considered (function Rx_Path_Check () 909 whose principle is described in more detail in relation to FIG. 11) for the transmission angle considered and selected by the transmitting device 900. The receiver device 901 then notifies the existence or absence of such a communication path (s) in the Sweep_report message 910 (the structure of which is detailed below in relation with FIG. 15). it returns to the transmitter device 900 at the end of the complete scan of its angular range of sight in reception. In the case where the message Sweep_report 910 received by the transmitter device 900 indicates that no communication path has been discovered, the transmitter device 900 reiterates the implementation of the Tx_Adjust () function as well as the transmission of a Sweep_Init message, until a Sweep_report message is received notifying the discovery of a communication path, or until it has performed a complete scan of its angular range of sighting in transmission. If the sending device 900 has not received the message Sweep_report 910 at the end of a time period T report 906, from the transmission of the message Sweep_Init 908, it abandons the communication path discovery process for the potential passive relay specified in the discovery request for communication paths Discovery_req 904. Once received a notification of the discovery of a communication path by the receiving device 901, or once the scanning of its angular range of sight in transmission completed (i.e., corresponding to the last implementation of the Tx_Adjust () 907 and Rx_Path_Check () functions 909 and the relative transactions 913 and 915), the transmitter device 900 transmits a Discovery_end message 918 (whose structure is detailed in relation to Figure 16) of end of communication path discovery for the potential passive relay specified in the request for discovery of communication paths Disc overy_req 904.

In FIG. 9, which deals with a protocol implemented for a couple of transmitter and receiver devices, it is important to note that the same transmitting device can, in the same way, process several receiving devices in parallel. Indeed, for the same angle of sight selected for the transmitting device, the set of receiving devices can travel all angles of sight of the angular range of view in reception. They can then determine in parallel whether the obstacle associated with the recovery zone can serve as a passive relay for the transmission of data by the transmitting device. FIG. 10 illustrates a communication path discovery protocol, according to a second particular embodiment of the invention. More precisely, FIG. 10 describes a communication path discovery protocol in which only the receiving device under consideration performs a reception antenna angle scan (also known as a viewing angle). In this case, the transmitter device 1000 and the receiver device 1001 seek to determine a communication path for which the transmitter device 1000 uses the quasi-omnidirectional antenna configuration transmission mode used in the determination of presence zones. obstacle (according to the principle described above, in connection with FIGS. 4, 5a and 5b), and for which the receiver device 1001 uses the selective transmission mode, as described in FIG. 6.

The transmitter 1000 and receiver 1001 devices initially perform a detection of the obstacles of the network (Network_Scan () functions 1002 and 1003) during which they determine geographical areas of the network, that is to say the zones covering the location of fixed obstacles. The receiving device 1001 calculates, in addition, during this detection phase, the angular aiming ranges relative to each of the fixed obstacles, then considered as potential passive relays. As in the case of the protocol described in relation to FIG. 9, the sending device can initiate the communication path discovery phase by means of a specific message. Otherwise, while the receiving device determines the target angular range (s), the transmitting device 1000 starts transmitting (during time intervals of the TDM sequence dedicated to the search for passive relay communication paths. ) a signal of predetermined characteristics known to the receiving device 1001. During the communication path discovery phase, the receiving device 1001 must scan a defined geographical area according to the overlap area in which the object (or obstacle) has been detected, in order to receive said predetermined characteristic signal transmitted by the transmitter device 1000. The receiver device 1001 then performs, for each potential passive relay of the network, a scanning of the associated reception angle of view angle, so to determine the existence, or absence, of communication path (s) involving the potential passive relay considered re (Rx_Path_Check () function 1004, whose principle is described in Figure 11). The receiving device 1001 then notifies the existence, or the absence, of such or such communication path (s) in the Sweep_report message 1005 (whose structure is detailed in FIG. 15) that it returns to the transmitting device 1000 at the end of the complete scanning of its angular range of sight in reception.

The transmitter device 1000 then acknowledges the reception of the Sweep_report message 1005 with the aid of the message Sweep_report_grant 1006 (the structure of which is detailed in FIG. 17). If the receiving device 1001 has not received a message Sweep_report_grant 1006 at the end of a time period Tgrant 1007, from the transmission of the message Sweep_report 1005, it considers any communication path discovered for the potential passive relay. as being undiscovered. It is clear that the protocol messages described with reference to FIG. 10 are not transmitted according to a selective data transmission mode between a transmitting device and a receiving device, but according to the transmission mode with a quasi-omnidirectional transmission antenna ( as described in connection with FIG. 4) allowing messages to be relayed via the mesh of the communication network. FIG. 11 shows a flowchart of a communication path detection algorithm for a receiver device in a wireless communication network, according to a particular embodiment of the invention. More specifically, this algorithm details step 803 of the algorithm of FIG. 8, namely the step of detecting a communication path involving a previously selected passive potential relay. It implements in particular the function Rx_Path_Check () (referenced 909 and 1004) discussed above in relation to FIGS. 9 and 10. The receiving device 901, for example, in a step 1100 of the algorithm, determines a viewing angle of its antenna in reception, this angle belonging to the angular range of sight in reception. To do this, the receiving device 901 varies, by a predefined step (1 degree, for example) the angular value of orientation of its antenna in reception compared to its previous value, so as to cover the entire range angular aiming in reception.

For each angular configuration thus tested, the receiving device also performs, in a step 1101, a measurement of the power of the received signal, then, in a step 1102, a comparison of this measurement with a predefined threshold, corresponding to a level communication quality characteristic of its receiving antenna (i.e., an expected reception quality level). Indeed, it is recalled here that the transmitting device transmits, for at least one time interval of the TDM sequence, dedicated to the passive relay communication path search, a signal of predetermined characteristics (defined according to a power threshold predefined by example) known from the receiver device. During the communication path discovery phase, the receiving device then performs a scan of the defined geographical area according to the overlap zone in which an obstacle has been detected, in order to verify that the received signal (in case a radio signal is detected) corresponds to the signal of predetermined characteristics transmitted by the transmitting device. If the measured power value is equal to or greater than the predefined threshold, the receiving device 901 then concludes, during a step 1103, the discovery of a communication path and notifies it to the transmitter device 900 (with the aid of FIG. Sweep_report message 1005 of FIG. 10) at the end of the complete scanning of its angular range of view in reception, during a step 1104. Once the angular range of sighting is completely scanned by the receiving device, the algorithm performs a transition in the end state 1105.

Figure 12 illustrates the structure of a communication path discovery request message 904, as described in Figure 9 and then referenced as a Discovery_req message. Such a message 904 includes: a field Pkt_ID 1200, informing about the nature of the message 904 (which is, in this case, Discovery_req); a field Dest_ID 1201, giving information on the unique identifier of the network allocated to the receiving device, that is to say the device which is the recipient of the present message 904; an Object_Descriptor field 1202, providing information on the overlap area relative to the position in the coverage area of the network of the potential passive relay to be tested, the latter comprising the following subfields: • Object_ID 1203, corresponding to an identifier associated with the relay potential liability to be tested; • Vertices_Nb 1204, giving information on the number of vertices of the considered area of cover, since such a zone is defined in a unique way by the coordinates of its vertices in an orthonormal frame, such as the reference 471 defined in figures 4 to 7; • V1 _X 1205 ... Vn_X 1207, corresponding to the abscissa of each of the vertices of the overlap area considered in an orthonormal frame, such as the reference 471 defined in Figures 4 to 7; • V1 _Y 1206 ... Vn_Y 1208, corresponding to the ordinates of each vertex of the geographical area considered in an orthonormal frame, such as the reference 471 defined in Figures 4 to 7.

Specifically, the field Object_ID contains an identifier, assigned by the device requiring the search for the ability of the obstacle to act as a passive relay for communication between two devices. The device receiving the message 904 then recognizes the obstacle by the coordinates of its vertices. In the remaining exchanges relating to this obstacle, this value Object_ID serves as an identifier of the obstacle, valid between the two communication devices.

FIG. 13 illustrates the structure of a discovery request acknowledgment message 905, as described in FIG. 9 and then referenced as a Discovery_req_grant message. Such a message 905 comprises: a field Pkt_ID 1300, providing information on the nature of the message 905 (the identifier is, in the present case, Discovery_req_grant); a Src_ID field 1301, giving information on the unique identifier of the network allocated to the sending device, that is to say the device which is the recipient of the present message 905 and having previously sent the message Discovery_req associated with this acknowledgment; an ACK_Status field 1302, providing information on the acknowledgment status in response to the request Discovery_req (acceptance or rejection). The rejection of the Discovery_req request could be related to, for example, the non-detection of the potential passive relay referenced in the Discovery_req message.

Fig. 14 illustrates the structure of a scan initialization message 908 of the reception aiming angular range, as described in Fig. 9 and then referenced as a Sweep_Init message. Such a message 908 includes: a field Pkt_ID 1400, informing on the nature of the message 908 (this identifier is, in this case, Sweep_Init). a field Dest_ID 1401, providing information on the unique identifier of the network allocated to the receiving device, that is to say the device which is the recipient of the present message 908; a field Tx_Angle_ID 1402, providing information on the angle of sight of the transmitting antenna of the transmitting device. It may be a simple identifier assigned by the transmitting device and known to the receiving device or the actual viewing angle value applied to the transmitting antenna. Figure 15 illustrates the structure of a communication path discovery report message 910 (or 1005), as described in Figures 9 and 10, and then referenced as a Sweep_Report message. Such a message 910 includes: a field Pkt_ID 1500, informing about the nature of the message 910 (this identifier is, in this case, Sweep_Report); a field Src_ID (1501), giving information on the unique identifier of the network allocated to the sending device, that is to say the device which is the recipient of the present message 910 (and having previously sent the message Sweep_Init associated with this report of discovery, in the case of the particular embodiment illustrated in Figure 9); a field Tx_Angle_ID 1502, giving information on the angle of sight value of the transmitting antenna of the transmitting device as indicated in the Sweep_Init message associated with this report; a Report_Status field 1503, informing on the status of the report returned in response to the Sweep_Init message (discovery or non-discovery of a communication path) for the angular orientation value as indicated in the Tx_Angle_ID 1502 field. FIG. 16 illustrates the structure of a communication path discovery end message 918 for a potential passive network relay, as described in Figure 9, and then referenced as a Discovery_End message. Such a message 918 includes: a field Pkt_ID 1600, providing information on the nature of the message 918 (this identifier is, in this case, Discovery_End); a field Dest_ID 1601, giving information on the unique identifier of the network allocated to the receiving device, that is to say the device which is the recipient of the present message 918; an Object_ID field 1602, giving information on the identifier associated with the potential passive relay, as initially entered in the Discovery_req message associated with the present message 918. FIG. 17 illustrates the structure of a message of acknowledgment report acknowledgment 1006. communication path, as described in Figure 10 and then referenced as Sweep_report_grant message. Such a message 1006 includes: a Pkt_ID 1700 field, informing on the nature of the message 1006 (this identifier is, in this case, Sweep_report_grant); a field Dest_ID 1701, specifying the unique identifier of the network allocated to the receiving device, that is to say the device which is the recipient of the present message 1006 (and having previously issued the Sweep_report message associated with this acknowledgment); an ACK_Status field 1702, which provides information on the acknowledgment status in response to the Sweep_report message. The acknowledgment can be negative for reasons of poor reception (such as for example when data are erroneous and inconsistent, due to an introduction of errors in a transmission channel). The device having emitted the Sweep_report message can then retransmit this message again, in order to ensure that the contents of the angle of view sweep report are taken into account (case not shown in FIG. 10). It should be noted that the sizing of the various constituent fields of the messages 904, 905, 908, 910, 918, 1006 (the structure of which is described above in relation with FIGS. 12 to 17), as a function of the protocol constraints of such a network, will appear obvious to the skilled person. It is the same for the messages relating to Figures 19 and 20 described below. It should be noted that the messages 905, 908, 910, 918, 1006 (the structure of which is described above with reference to FIGS. 13 to 17) may further comprise an Object_ID field (not shown in FIGS. 13 to 17 ) as described in connection with Figure 12, in order to unambiguously identify the passive relay to which these messages refer. It is the same for the messages relating to Figures 19 and 20 described below.

FIG. 18 is a discussion of a flow diagram of an algorithm for selecting a communication path for a pair of transmitter and receiver devices, according to a particular embodiment in accordance with the invention. Note that the present algorithm can be implemented statically, when establishing a new communication path between the transmitter and receiver devices. It can also be implemented dynamically as part of an update of an existing communication path.

The implementation of the algorithm in the context of the particular embodiment described in FIG. 9 is considered here. In a step 1800, the transmitting device considered verifies all the possible communication paths, including the predetermined communication path ( corresponding to that of FIG. 6, for example), as well as the set of additional communication paths involving a passive relay of the network, discovered during the implementation of the algorithms and protocols of FIGS. 8 to 11. In a step 1801 , the transmitting device then determines all the disturbances of the network. It can thus be actual disturbances, that is to say disturbing obstacles of the network (according to the principle of Figures 4, 5a and 5b). It is noted that the skilled person may further define other perturbation criteria and methods of characterization of associated disturbances. In a step 1802, the transmitting device then selects, from among the set of possible communication paths considered in step 1800, the communication path that has the least actual disturbances or the lowest probability of disturbance, then notifies the receiving device during a step 1803. To do this, the transmitting device transmits, to the receiving device of the pair of devices, a Path_select communication path selection message (the structure of which is detailed in FIG. 19) providing information on the path selected. The receiving device will then return, upon receipt of the Path_select message, an Acknowledgment message Path_select_ack (the structure of which is detailed in FIG. 20). Subsequently, the receiver device uses, for communications with the transmitting device, the viewing angle obtained during the execution of the algorithm described in relation to FIG. 9 or obtained during the execution of the algorithm. described in relation to FIG. 10, as the case may be. The transmitting device uses, for its part, for communications with the receiving device, the viewing angle obtained during the execution of the algorithm described in connection with FIG. 9, or a quasi-omnidirectional antenna configuration, depending on the case. The algorithm then performs a transition in the end state 1804.

Figure 19 illustrates the format of a communication path selection message as described in Figure 18 and then referenced as a Path_Select message. This message includes: a field Pkt_ID 1900, informing about the nature of the message (this identifier is, in this case, Discovery_End); a field Dest_ID 1901, informing on the unique identifier of the network allocated to the receiving device that is to say the device which is recipient of this message; a Native_Path_ID field 1902, specifying the unique identifier of the predefined communication path, in the case where the selected path is a pre-established path (as opposed to an additional communication path discovered using the present invention). This field may furthermore take a null value, or Null_ID, indicating that the selected communication path is not a pre-established path, but an additional communication path discovered using the present invention. a field Relay_ID 1903, corresponding to an identifier associated with the passive relay associated with the additional communication path selected, this field giving the value identical to the value of the field Object_ID 1603, described with reference to FIG. 16. FIG. an acknowledgment message for selecting a communication path, as described in FIG. 18 and then referenced as a Path_Select_Ack message. This message includes: a field Pkt_ID 2000, informing on the nature of the message (this identifier is, in this case, Path_Select_Ack); a Src_ID field 1701, providing information on the unique identifier of the network allocated to the sending device, that is to say the device which is the recipient of the present message (and having previously sent the message Path_Select associated with this acknowledgment); An ACK_Status field 1302, providing information on the acknowledgment status returned in response to the Path_Select message. The acknowledgment can be negative for reasons of possible poor reception (such as for example in the case of erroneous and inconsistent data, due to an introduction of errors in a transmission channel). The device having sent the message Path_Select can then retransmit this message again, in order to ensure that the selection of the communication path is taken into account (case not shown in the flowchart of FIG. 18). 10

Claims (10)

REVENDICATIONS1. A method of determining at least one communication path in a wireless communication network (100) comprising a set of pairs consisting of a transmitting device and a receiving device, said method being characterized by comprising steps of, for communication to be established between a transmitting device (180) and a receiving device (140): - determining (801) an obstacle presence area (700) by communication quality analysis between devices of said couples; obtaining reception quality level values, by the receiving device (140) of a given signal transmitted by the transmitting device (180), by scanning, in reception and / or transmission, of at least a part of an angular aiming range (709, 712), an angular aiming range (709, 712) being representative of a set of antenna orientation angles oriented according to the obstacle presence area (700) determined ; determining (803) at least one communication path, by selecting an antenna orientation angle, in the angular aiming range (709, 712), for which the received reception quality level value is greater than at a predetermined threshold. 2. Method according to claim 1, characterized in that said obstacle presence zone (700) is determined by mutual overlap of at least two intersection areas of communications coverage areas of a pair of transmitter devices and receiver, each of them having a state of disturbance according to a determined criterion of quality of communication between the devices of a pair of transmitter and receiver devices. 3. Method according to any one of claims 1 and 2, characterized in that it comprises a step (800) of checking whether an obstacle, present in the obstacle presence zone (700), is fixed, by analyzing a disturbance state of said obstacle presence area (700) for a predetermined time, and in that said step of obtaining reception quality level values is performed in case of positive verification. The method according to any one of claims 1 to 3, characterized in that, in said step of obtaining reception quality level values, the angular aiming range (709, 712) is determined so that it defines, for a receiver device (140) or an associated transmitter device (180), a scanned coverage area whose ends are defined by edges or end vertices of the obstacle presence area (700). 5. Computer program product downloadable from a communication network and / or recorded on a computer readable medium and / or executable by a processor, characterized in that it comprises program code instructions for the implementation of the Method according to at least one of Claims 1 to 4, when said program is executed on a computer. Computer-readable storage medium, possibly totally or partially removable, storing a computer program comprising a set of instructions executable by a computer to implement the method according to at least one of claims 1 to 4. 7. Device for determining at least one communication path in a wireless communication network (100) comprising a set of pairs consisting of a transmitting device and a receiving device, said determining device being characterized in that it comprises, for a communication to be established between a transmitter device (180) and a receiver device (140): - first means for determining an obstacle presence area (700) by communication quality analysis between devices of said couples; means for obtaining reception quality level values, by the receiver device (140) of a given signal transmitted by the transmitting device (180), by scanning, on reception and / or on transmission, of least part of an angular aiming range (709, 712), an angular aiming range (709, 712) being representative of a set of antenna orientation angles oriented according to the obstacle presence area (700) determined; second means for determining at least one communication path, by selecting an antenna orientation angle, in the deviated angular range, for which the reception quality level value obtained is greater than a threshold predetermined. 8. Device according to claim 7, characterized in that said obstacle presence area (700) is determined by mutual overlap of at least two intersection areas of communications coverage areas of a pair of transmitter devices and receiver, each of them having a state of disturbance according to a determined criterion of quality of communication between the devices of a pair of transmitter and receiver devices. 9. Device according to any one of claims 7 and 8, characterized in that it comprises means for verifying that an obstacle, present in the obstacle presence zone (700), is determined fixed, by analysis d a state of disturbance of said obstacle presence zone (700) for a predetermined duration, and in that said means for obtaining reception quality level values are activated in the case of a positive verification. 10. Device according to any one of claims 7 to 9, characterized in that the angular range of sight (709, 712) is determined so that it defines, for a receiving device (140) or a transmitter device (180) ) associated, a swept area of coverage whose ends are defined by edges or end vertices of the obstacle presence area (700).