• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    This method, executed in a group of nodes of the ad hoc networks (1) comprising a source (10), first and second relays (11, 12) and a recipient (13), the relays being adjacent to the source, the recipient being a neighbor of the relays, the source having useful data to retransmit to a final recipient (15) by a routing path passing through the first relay (11), then the recipient (13), consists in: calculating a first characteristic quantity d an elementary path between the source (10) and the receiver (13), via the first relay (11) and a second magnitude characteristic of an elementary path between the source (10) and the recipient (13), via the second relay (11); checking the respect of a criterion for the first characteristic quantity; and, in case of negative verification, use the second relay (12) to relay the payload from the source (10) to the recipient (13).
    公开号:FR3037462A1
    申请号:FR1501223
    申请日:2015-06-12
    公开日:2016-12-16
    发明作者:Hicham Khalife；Hicham Anouar；Didier Pirez；Vania Conan；Jawad Seddar
    申请人:Thales SA；
    IPC主号:
    专利说明:

    [0001] FIELD OF THE INVENTION The present invention relates to a method for local correction of the routing path in an ad hoc network. A node of such a network is both a terminal node, i.e., initial source or final recipient of a data message, or an intermediate node for receiving and retransmitting a data message along. a routing path between an initial source and an end recipient of the data message.
    [0002] In such a network, a node is considered to be neighbor to another node when they are close enough that a communication link can be established. In the following, the neighboring nodes of a node are said nodes of rank one of this node, and the neighboring nodes of the nodes of rank one of this node are said nodes of rank two of this node. Thus, from the considered node, a node of rank one is accessible by at least one jump, or jump ("hop" in English), while a node of rank two is accessible by at least two jumps. An ad hoc network is a network whose topology can evolve over time, with the displacement of the nodes relative to each other and the modification of the links between nodes.
    [0003] A routing table, allowing the nodes to share the same vision of the network and each node to know which neighboring node retransmit a data message so that the latter is routed to a close to a final recipient, must be updated regularly to take into account the evolution of the topology. To do this, the nodes regularly transmit signaling signals. Such a signal comprises in particular a unique identifier of the transmitter node on the network. The signaling signals received by a node allow the latter to know the nodes which, at the current time, are in its vicinity. This neighborhood information at a hop of a node is, in a particular type of routing, transmitted to a central node of the network which is connected to a device able to determine the topology of the network and, from this, to build a general routing table. This defines, for each pair of nodes consisting of an initial source node and a final destination node, the unique routing path to be followed by a data message across the network, i.e. an ordered list of intermediate nodes for conveying a data message between the initial source node and the final destination node. The device then generates a local routing table, specific to a particular node, and which indicates the identifier of the neighbor node to which the node concerned is to retransmit a data message addressed to a final destination node. The local routing table of a node therefore associates the identifier of an end recipient with the identifier of a node of rank one. The local routing tables are then transmitted to each of the nodes of the network. Other types of routing are known to those skilled in the art. However, generally speaking for all types of routing, the update of the local routing table of a node requires a long time between the determination of the neighborhood of this node, the sharing of a change of neighborhood with the others. network nodes so that the nodes have the same vision of the network, and the definition of a local routing table for the node considered, allowing it to properly retransmit the messages. This time increases in particular according to the number of nodes constituting the network. Thus, it is possible that the local routing table once available to a node does not correspond more exactly to the topology of the network around this node at the current time.
    [0004] For example, a node may be out of the vicinity of the considered node. This leads to a break in communication to the final destination nodes associated with this rank one node in the local routing table. For example still, the quality of the communication with a node of rank one can be degraded, this neighboring node being momentarily masked. This leads to a drop in the quality of communication 20 to the final destination nodes associated with this rank one node in the local routing table. It is then necessary to repeat the transmission of the data message and consequently lose bandwidth. But, the routing table can not be updated with too low a frequency. Indeed, the amount of signaling messages circulating on the network so that the 25 nodes can share a common view of the network topology reduces the bandwidth for the data messages. The object of the invention is therefore to overcome this latency problem in updating the routing information used by a node. The subject of the invention is therefore a method for local correction of the routing path in an ad hoc network comprising a plurality of nodes, each node comprising transceiver means capable of receiving and transmitting data messages, the nodes communicating between they by sending signals corresponding to said data messages in time slots organized in frames, the frames being synchronized through the ad hoc network, a routing of the data messages being carried out through the ad hoc network on the basis of a routing table defining a routing path for the communication between each node pair of the network, characterized in that said method is implemented in a group of nodes of the ad hoc networks comprising a source node, at least first and second relay nodes, and a destination node, the first and second relay nodes being adjacent to the source node, the destination node etan t neighbor of the first and second relay nodes 5 but not neighboring the source node, the source node having useful data to retransmit to an end recipient and the routing table indicating that the corresponding routing path passes through the first relay node then by the destination node, and in that said method comprises the steps of: calculating, by the source node, a characteristic quantity of an elementary path between the source node and the destination node, via the first node relay and a magnitude characteristic of an elementary path between the source node and the destination node via the second relay node; verifying, by the source node, compliance with a predetermined criterion for said characteristic quantity of the elementary path between the source node and the destination node, via the first relay node; and, in case of negative verification, - use of the second relay node to relay the data message from the source node to the destination node. The invention solves the latency problem mentioned above, by proposing a local correction mechanism of the routing path allowing a node to take into account any modification of its neighborhood at a jump. According to particular embodiments, the method comprises one or more of the following characteristics, taken individually or in any technically possible combination: during a signaling slot of each frame, each node has the possibility of transmitting a signal. a signaling message comprising signaling information, the signaling information enabling each node to determine its rank one neighboring nodes, a link quality with each of its rank one neighboring nodes, its rank two neighboring nodes, and a quality connecting a neighboring node of rank one and a neighboring node of rank two, the link qualities allowing, in the calculation step, a source node to determine a communication quality. the step of using the second relay node consists of relaying the payload data to the destination node at the same time by the elementary path between the source node and the destination node, via the first relay node, and by the elementary path 35 between the source node and the destination node, via the second relay node. The step of using the second relay node implements a mode of operation in beam formation, in which first and second relay communication messages, transmitted respectively by the first and second relay nodes, interfere constructively. at the destination node, at least in their respective payload portions comprising the retransmitting data, the first and second relay communication messages being transmitted during a dedicated relay communication slot of the frame. the destination node measures a phase of a signal emitted by a relay node from a pattern, characteristic of the transmitting relay node, provided in a header portion of the relay communication message; chose one of the relay nodes as master relay nodes; calculates for each of the other relay nodes, called slaves, a phase shift resulting from the difference between the phase measured for the slave relay node considered and the measured phase for the master relay node; and transmits the calculated phase shift to the corresponding slave relay node in an adjustment message transmitted in a dedicated adjustment slot of the frame, and a relay node having received an adjustment message adjusts a phase of its transmission means -reception so as to cancel the phase shift indicated in said adjustment message. each relay node is able to calculate a frequency drift of its transmission-reception means from the phase shift contained in a succession of adjustment messages transmitted by the same destination node and to adjust the frequency of its means of transmission. transmitting-receiving so as to correct said frequency drift, at least during the relay communication slot for the transmission of a relay communication message to said destination node. the characteristic quantity being a communication quality along an elementary path, the predetermined criterion consists in verifying that the characteristic quantity of the elementary path between the source node and the destination node, via the first relay node, which is the node relay indicated by the routing table, is greater than the characteristic quantity of the elementary path between the source node and the destination node, via the second relay node, the step of using the second relay node of relaying the payload data to the destination node only by the second relay node, replacing the first relay node. The invention also relates to an ad hoc network comprising a plurality of nodes adapted to receive and transmit data messages and communicating with each other by sending signals in time slots arranged in frames, characterized in that each node comprises means for implementing the above method.
    [0005] According to particular embodiments, the network comprises one or more of the following characteristics, taken separately or in any technically possible combination: the frames comprise: a signaling slot, allowing each node to transmit a signal of signaling comprising signaling information, the signaling information enabling each node to determine its rank one neighboring nodes, a link quality with each of its rank one neighboring nodes, its rank two neighboring nodes, and a link quality between each node of rank one and each node of rank two; A source communication slot, allowing a node operating as a source node to transmit a source communication message to a rank one node operating as a relay node, the source communication message including the payload data to be transmitted to a source node final recipient; A relay communication slot, allowing a node operating as a relay node to transmit a relay communication message to a destination node, the relay communication message comprising a header portion incorporating a pattern, characteristic of the transmitting relay node , allowing the destination node to calculate a phase of the signal corresponding to the relay communication message, and a payload portion comprising the useful data to be relayed to the destination node; And an adjustment window, allowing the node operating in the destination node to transmit an adjustment message to a relay node of a set of relay nodes used in a beamforming mode, the adjustment message comprising a phase shift. each destination node of a plurality of relay communication messages transmitted by relay nodes of a set of relay nodes used in a beamforming mode, is able to calculate a phase for each of said relay nodes from the signal corresponding to the incident relay communication message, determining a phase shift between at least two of said relay nodes and transmitting the calculated phase shift to one of said at least two relay nodes, in an adjustment message transmitted in a slot of adjustment dedicated to the frame. each node operating as a relay node is able to estimate a frequency drift of its transmission-reception means from the phase shift contained in a succession of adjustment messages transmitted by the same destination node and to adjust its transmission means -reception to correct said drift. The routing table of a node comprises, for each recipient of useful data, the neighboring node of rank one of the considered node and the neighboring node of rank two of the considered node along the routing path. The features and advantages of the invention will appear on reading the following description, given solely by way of example, and with reference to the appended drawings, in which: FIG. 1 is a diagrammatic view of a ad hoc network at a given time; FIG. 2 is a representation of the format of the communications frames used by the network of FIG. 1; and - Figure 3 is a flowchart of the routing correction method according to the invention. The network 1 illustrated in FIG. 1 is for example an ad hoc communication network between individuals on a field of operations.
    [0006] Each individual is equipped with a transceiver constituting a node of the network. The network 1 illustrated in FIG. 1 is composed of fifteen nodes referenced from 10 to 24. The nodes are identical to each other. In a manner known per se, according to the OSI model, a node comprises, in particular, a data link layer, hereinafter referred to as the MAC layer (acronym "Media Access Control" or "access control support ") between a physical layer and a routing layer. By layer is meant all the hardware or software means for implementing the corresponding function. The MAC layer of each node has communication means for receiving and transmitting data messages. The data messages are transmitted as signals, for example radio, in a given channel. The communication means are adapted to adjust the phase and the frequency of these signals. Network 1 is a time division multiple access network or TDMA network for "Time division multiple access". The time is thus subdivided into frames 30 ("Frame_t" in FIG. 2) of constant duration, and each frame itself is subdivided in a predetermined manner into time slots ("slot" in English). The different nodes of the network are synchronized with each other, for example by a synchronization signal delivered by a satellite positioning system. In this way, each node knows which slot of the frame corresponds to the current time.
    [0007] The node 16 is for example connected to a device 30 for determining the topology of the network, periodically generating a general routing table from the determined topology, and communicating it to each of the nodes of the network a table of local routing. The routing and the manner of obtaining a local routing table do not form part of the invention and other types of routing can be implemented. The routing layer of each node thus stores a current local routing table. The general routing table makes it possible to define, between each pair of nodes consisting of an initial source node and a final destination node, a single routing path. Thus, between the node 14, as the initial source node, and the node 15, as the final destination node, the general routing table defines the routing path indicated by the continuous arrows in FIG. 1. In particular, between the nodes 10 and 13, the planned routing path passes through the intermediate node 11. In the present invention, the local routing table of a node is such that it associates an identifier of a final destination node, to a identifier of a rank one node and an identifier of a rank two node. For example, the local routing table of the node 10, associates with the node 15, the node 11 of rank one and the node 12 of rank two. However, the local routing table is updated at a reduced frequency compared to the movements of the nodes in the network 1 and the modification of the neighborhood of the considered node. For example, the intermediate node 12, which, at the moment considered, is in the neighborhood at a jump of the node 10 can serve as a relay between the nodes 10 and 13, or in the place of the intermediate node 11 provided by the routing, in addition to the intermediate node 11 provided by the routing. The method of correcting the routing path will allow, at the MAC layer of the network, the use of intermediate nodes, other than that indicated by the routing, to relay the information between a source node and a destination node, located two hops from the source node along the routing path. The method of correcting the routing is thus implemented locally in a group of nodes consisting of: a source node, such as the node 10, as the source node of the data message 30 to be retransmitted to a final destination node, such as that the node 15; A destination node, such as node 13, as a node to propagate the data message, located two hops from the source node along the routing path to the final destination node; At least two relay nodes, such as the first relay node 11 and the second relay node 12, as intermediate nodes for relaying the data message between the source node 10 and the destination node 13. The first relay node 11 being located on the routing path while the second relay node 12 is located outside the routing path. The relay nodes 11 and 12 are located in the vicinity of the source node, 11, and in that of the destination node 13, neighborhoods represented by a circle in FIG. 1. On the other hand, the destination node 13 is not in the neighborhood of a jump of the source node 10, but in the two-hop neighborhood of the source node 10.
    [0008] As a variant, more than two relay nodes are, at the instant considered, in the vicinity of the source node 10 and in that of the destination node 13, and are used for the correction of the routing path. Referring to FIG. 2, the network 1 uses time slots to transmit the data messages, these slots being distributed in frames. The subdivision of the slot frames is constant from frame to frame. The duration of each slot is constant from one frame to another. The duration of the frames is therefore constant. Each frame is broken down into slots according to the following format: a signaling slot Si; a source communication slot S2; a relay communication slot S3; and an adjustment slot S4. During the signaling slot If, for a duration of 15 ms for example, a node may issue a signaling message including signaling information.
    [0009] The signaling information includes an identifier of the transmitting node. A receiving node of the signaling message is thus able to determine all the nodes in its vicinity. The signaling information comprises, for example, a Walsh sequence or the equivalent, so as to enable a receiving node of the signaling message 30 to determine a quality of the link with the transmitting node. The quality of the link is for example a signal-to-noise ratio (SNR) or a signal receiving power (RSSI for "Received Signal Strength Indication") or any quantity measurable by the MAC layer of the receiving node. The signaling information comprises, for example, the quality of the link 35 between the transmitting node and each of its neighboring nodes. Thus, the receiving node of the signaling message knows, for each of its neighboring nodes, the quality of the link between this neighboring node, and each of the neighboring nodes of this neighbor node. That is, the receiving node knows the quality of the link between a node of rank one and a node of rank two. The MAC layer of each node thus maintains a list associating with the identifier 5 of each node of rank one, the quality of the link with this node of rank one, as well as the identifiers of each node of rank two, and the quality of the link between this node of rank two and the node of corresponding rank. For each node of rank two of the list, the MAC layer of a node is able to calculate a quality of the communication along the elementary path between the node 10 considered and this node of rank two via the node of a corresponding rank. For example, a max-min algorithm is used that takes into account the link quality on the link between the considered node and the rank one node, and the link quality on the link between the rank one node and the link node. rank two. During the source communication slot S2, of a duration of 34 ms, for example, a node operating as a source node may transmit a source communication message to a relay node. The source communication message comprises the useful data to be transmitted to the final destination node, as well as an identifier of the two-hop destination node 13 and an identifier of the or each one-hop relay node, 11 or 12, to relay the data. useful to this destination node. It should be noted that the addressing can be done by explicitly addressing each of the recipients of the data message, or by addressing the message to a group of nodes, which identifies several recipients who will recognize each other. During the S3 relay communication slot, of a duration of 35 ms, for example, a relay node, such as nodes 11 and 12, may issue a relay communication message. Each relay communication message, during a first sub-slot of 1 ms for example, a header portion incorporating a characteristic pattern of the transmitting relay node, allowing the destination node to calculate a phase for the transmitting relay node 30. Each relay communication message comprises, during a second sub-window of 34 ms for example, a portion of payload comprising the payload data to be relayed to the destination node 13. During the adjustment slot S4, of a duration of For example, a destination node, such as node 13, may send an adjustment message to a relay node from which it has received a relay communication message. The adjustment message includes an identifier of this relay node and a phase shift Aq).
    [0010] It will be appreciated that slot S4 as well as the 1 ms sub-slot of S3 are only useful for the beamforming mode of operation 300 which will be described below.
    [0011] Each node is capable of implementing the method 90 of FIG. 3. The method 90 includes a neighborhood discovery algorithm 100 enabling the MAC layer of a node to discover its environment. More specifically, in step 110, each node transmits, in the signaling slot Si, a signaling message comprising the signaling information indicated above. In step 120, the MAC layer of a receiving node of a signaling message updates its list with the information contained in this signaling message. In particular, based on the Walsh sequence at the beginning of the signaling message, the receiving node determines the quality of the link with the sending node of the signaling message. With the list, each node knows not only its one-hop neighborhood, but also its two-hop neighborhood. Some of the information contained in the list may be transmitted on the network 1 to the node 16 connected to the update device of the routing table.
    [0012] However, they are transmitted with a larger time scale (lower frequency), every 100 ms for example, (to minimize the burden of updating the routing table on the network. The type of routing used is generally independent and is performed separately on a larger time scale, and the local routing table stored by the routing layer of a node is periodically refreshed. node is constructed to indicate to the considered node the next two nodes on the routing path to an end recipient.
    [0013] Between two update times of the routing, a group of nodes implements the retransmission steps 200 of the method 90. In the following, these steps are illustrated by the group consisting of the nodes 10, 11, 12 and 13. The retransmission of a message by the source node 10 to a rank one relay node takes into account the routing path indicated by the local routing table and possibly a correction to the routing path indicated by the local routing table.
    [0014] Thus, in step 210, the MAC layer of the source node 10 receives a data message. The source node MAC layer 10 extracts the identifier of the final destination node from the received data message. In step 220, if the identifier of the final destination node is not the identifier of the source node 10, the MAC layer of the source node 10 interrogates the routing layer, in order to know the identifier of the node to a jump and the node identifier to two hops from the routing path. In step 230, in consultation with the local routing table, the routing layer identifies the routing path leading from the source node to the final recipient and extracts the node identifier at a hop and the node identifier at two jumps. when it exists (hypothesis implicitly made for the implementation of the present method). Thus, to route a data message to the final destination node 15, the routing layer of the source node 10 identifies, on the routing path defined by the local routing table, the rank one node 11 and the rank two node. 13. These two identifiers 15 are passed through the routing layer to the MAC layer. In step 240, based on the identifier of the two-hop node taken as the destination node, the MAC layer consults the list and identifies the rank one nodes that can relay a data message to the destination node. Thus, the source node 10 identifies the first relay node 11 and the second relay node 12 as making it possible to reach the destination node 13. In step 250, for each of these rank one relay nodes, the MAC layer of the node source calculates the quality of the communication of the elementary path making it possible to pass from the source node to the destination node, via the node of rank one considered. The quality of communication along an elementary path is evaluated by taking into account the quality of the link between the source node and the rank one node, as well as the quality of the link between the rank node considered and the rank two recipient node. The link qualities are indicated in the MAC layer list of the source node. In step 260, the MAC layer of the source node applies a first criterion to select an elementary path. For example, this first criterion consists in selecting the elementary path presenting the best quality of communication among the various elementary paths making it possible to reach the destination node. The MAC layer retains the identifier of the rank one relay node associated with the selected elementary path as the identifier of the intermediate node to which the data message is retransmitted. For example, if the quality of the communication along the second elementary path passing through the second relay node 12 is better than the quality of the communication along the first elementary path passing through the first relay node 11, the source node 10 retains the identifier of the second relay node 12 as intermediate relay node to which retransmit the data message to the destination node 13.
    [0015] In step 270, a second criterion is checked on the level of the communication quality along the selected elementary path. For example, and preferably, the second criterion consists in verifying whether the quality of the link between the relay node selected and the destination node is greater than a predetermined high threshold (depending on the radio operating parameters of the antenna of which the nodes). Alternatively, other first and second criteria may be implemented. The first criterion could also be identical to the second criterion. If this second criterion is verified, in step 280, the source node 10 sends a source communication message to the intermediate relay node retained, in this case the second relay node 12. This source communication message is transmitted in the slot S2. The source communication message includes, in addition to the useful data, the identifier of the relay node 12 and the identifier of the destination node 13, so that the relay node 12 knows which node to retransmit the useful data. In step 290, the relay communication message is transmitted by the relay node 12 to the destination node 13. This relay communication message is transmitted in the slot S3. It comprises, in its portion of payload, useful data to route to the final recipient. The relay node does not consult its routing table since the source node imposes the destination node in the source communication message. On the other hand, if the second criterion is not verified and the quality of the link 25 between the rank one neighbor and the rank two neighbor of the selected elementary path is less than or equal to the high threshold, the MAC layer of the source node 10 goes into a mode of operation in beam formation, so that the steps referenced by the numeral 300 in Figure 3 are performed. The beam formation consists in using a set of rank 30 relay nodes for retransmitting simultaneously to the same destination node relay communication messages whose payload portions are identical and include the payload. In order for the payload portions of the signals transmitted by the different relay nodes to interfere constructively at the destination node, it is necessary, in addition to the synchronization of the slot S3, to adjust the phase and possibly to adjust the frequency of these signals.
    [0016] More specifically, in step 310, the MAC layer of the source node 10 extracts a set of rank one relay nodes from the list. For example, the rank-one relay nodes corresponding to an elementary path whose communication quality is less than a predetermined low threshold are not retained. The set of relay nodes 5 groups the relay nodes of rank one used to form the beam to the node of rank two, destination. Here, the set of relay nodes comprises the first and second relay nodes 11 and 12. In step 320, the source node 10 transmits, in the slot S2, a source communication message to each of the relay nodes of the set relay nodes. This message comprises the identifiers of the different relay nodes of rank one of the set of relay nodes as well as the identifier of the node of rank two recipients. The payload portion of this message includes the payload to the final destination node 15. In step 330, each of the relay nodes, 11 and 12, having received the source communication message from the source node 10, transmits, in the slot S3, a relay communication message to the destination node 13. In particular, the relay communication message incorporates a header portion comprising for example a specific Walsh sequence of the transmitting relay node, 11 or 12, and a portion of payload with the useful data to be transmitted. Again, the relay node does not consult its routing table since the source node imposes the destination node in the source communication message. The relaying of the useful data is essentially done at the MAC level of the relay node. In step 340, the destination node 13 receives relay communication messages in the time slot S3. It normally retransmits the payload to the next relay node along the routing path to the final destination node 15. To reduce interference between the relay node signals of all the relay nodes used to form the beam, the node recipient 13 analyzes the Walsh sequences of the header portions of the relay communication messages received. The relay node is thus able to measure, for each relay node, a phase 30 of the signal transmitted by this relay node. The manner of calculating the phase from information such as a Walsh sequence is known to those skilled in the art. In step 350, the destination node 13 selects a relay node from among the nodes of the set of relay nodes used to form the beam as a master relay node (for example relay node 11). The other nodes of all 35 relay nodes used to form the beam are then called slave nodes (for example the node 12). For each of the slave nodes, the destination node 13 calculates a phase difference Δg) by difference between the phase (1) measured for the slave node considered and the phase cp measured for the master node. The destination node 13 thus calculates a phase shift Aq) for the relay node 12. In the step 360, the destination node 13 transmits, in the time slot S4, an adjustment message to each of the slave nodes of the set of nodes. relay nodes used to form the beam, this adjustment message comprising the eq phase shift calculated for this slave node. Thus, the destination node 13 transmits the phase shift Acp to the relay node 12 In step 370, the relay node 12, having received an adjustment message in the adjustment slot S4, adjusts the phase of its transmission module -Receiving to cancel the phase shift Acp indicated by the destination node 13. This adjustment is made at the beginning of the slot S3 of the next frame. Thus, when transmitting a relay communication message in the slot S3 of the next frame, the different relay nodes of the set of relay nodes used to form the beam will be in phase, (provided that the positions Relay and recipient nodes have not changed too much in the meantime, so that the interference between the signals they emit will be reduced. The transmission to the destination node will therefore be better than that along the elementary path provided by the routing.
    [0017] Advantageously, in step 380, a slave node corrects the frequency drift of its transmitting-receiving module. For example, the second relay node 12 calculates a time variation of the zup phase shift calculated by the destination node 13. To do this, the relay node 12 stores the phase shift Acp transmitted by the destination node 13 to each frame. By dividing the difference between two successive phase differences Aw by the duration At of a frame, the relay node 12 determines a frequency drift Lf. In the relay communication slot S3, the relay node 12 then dynamically adjusts the operating frequency of its transceiver module to compensate for this frequency drift. Thus, if the adjustment of the phase makes it possible to reduce the interference at the beginning of each S3 relay communication slot, the correction of the frequency 30 makes it possible to maintain this interference reduction throughout the relay communication slot 33. The different nodes Relay of all the relay nodes used to form the beam will be in phase not only at the beginning but throughout the relay communication slot S3. The transmission to the destination node will be further improved.
    [0018] In a variant, the routing correction method only includes the step of selecting the relay node located on the elementary path having the best quality of communication. If this relay node is different from the relay node indicated by the routing, it substitutes for the latter and the data message is relayed only by this substitution rank one node. Thus, the use of another relay node than indicated by the routing locally improves the communication. In another variant, the method for correcting the routing comprises only the beam formation as soon as the quality of communication on the elementary path passing through the relay node indicated by the routing is insufficient. The use of the relay node different from the relay node indicated by the routing then reinforces the relay to the destination node, the different relay nodes operating simultaneously. Thus, the use of another relay node than indicated by the routing locally improves the communication. It should be noted that in the beam formation implemented in the present method, it is the destination node which controls the adjustment of the relay nodes used. There is no communication between the relay nodes between them. It should also be noted that at the instant considered, the relay node indicated by the routing may no longer be in the vicinity of the source node considered. Thus, the implementation of the method makes it possible, when such a situation arises, not to interrupt the communication in progress between the initial source node and the final destination node. Finally, the beam formation has the advantage of increasing the range of communication to the destination node. Consequently, the communication is less sensitive to the distance of the destination node from the relay node indicated by the routing. Those skilled in the art will recognize that in the present method, every other node along a given routing path may be considered as the source node and the rank one nodes of a source node as relay nodes. The possible correction of the routing path takes place at the relay nodes of the routing path considered. However, both jumps, the method provides to return to the predefined routing path. There can therefore be no discrepancy that would cause the data message to progressively deviate from the routing path. The correction of the routing path is transparent for the routing layer of the nodes. In particular, the good and good two neighbor information of a source node is not retransmitted at each change to the routing layer 35 pending an update of the local routing table. The method according to the invention therefore reduces the amount of routing: the amount of signaling information for updating the routing to propagate on the network is reduced; the validity period of a routing table is increased. The bandwidth is therefore allocated to the transmission of useful data. 5
    权利要求:
    Claims (12)
    [0001]
    CLAIMS 1.- Method (90) for local correction of the routing path in an ad hoc network (1) comprising a plurality of nodes, each node comprising transceiver means adapted to receive and transmit data messages, the nodes communicating between them by sending signals corresponding to said data messages in time slots (S1, S2, S3, S4) organized in frames, the frames being synchronized through the ad hoc network, a routing of the data messages being carried out through the ad hoc network based on a routing table defining a routing path for the communication between each pair of nodes of the network, characterized in that said method is implemented in a group of nodes of the ad hoc networks comprising a source node (10), at least first and second relay nodes (11, 12), and a destination node (13), the first and second relay nodes being adjacent to the source node, the node of the receiver being adjacent to the first and second relay nodes but not adjacent to the source node, the source node having useful data to retransmit to an end recipient (15) and the routing table indicating that the corresponding routing path passes through the first relay node (11), then by the destination node (13), and in that said method comprising the steps of: - calculating (250), by the source node (10), a characteristic quantity of a path elementary between the source node (10) and the destination node (13), via the first relay node (11) and a characteristic quantity of an elementary path between the source node (10) and the destination node (13), via the second relay node (11); verifying (270), by the source node (10), the respect of a predetermined criterion for said characteristic quantity of the elementary path between the source node and the destination node, via the first relay node; and, in the case of a negative check, - using the second relay node (12) to relay the payloads from the source node (10) to the destination node (13).
    [0002]
    The method according to claim 1, wherein, during a signaling slot (Si) of each frame, each node has the possibility of transmitting a signaling message comprising signaling information, the signaling information enabling at each node determining its rank one neighboring nodes, a link quality with each of its rank one neighboring nodes, its rank two neighboring nodes, and a link quality between a rank one neighbor node and a node 3037462 second-order neighbor, the link qualities allowing, in the computing step (250), a source node (10) to determine a communication quality.
    [0003]
    3. A method according to claim 1 or claim 2, wherein the step of using the second relay node (12) is to relay the payload data to the destination node (13) at a time by the elementary path between the source node (10) and the destination node (13), via the first relay node (11), and the elementary path between the source node (10) and the destination node (13) via the second relay node (12). ). 10
    [0004]
    4. A method according to claim 3, wherein the step of using the second relay node (12) implements a beam-forming mode of operation, wherein first and second relay communication messages, respectively transmitted by the first and second relay nodes, constructively interfere at the destination node (13), at least in their respective payload portions including the data to be retransmitted, the first and second relay communication messages being transmitted during a slot; communication relay (S3) dedicated to the frame.
    [0005]
    The method according to claim 4, wherein the destination node (13): measures a phase (p) of a signal transmitted by a relay node (11, 12) from a pattern characteristic of the transmitter relay node, provided in a header portion of the relay communication message; - chooses one of the relay nodes as master relay nodes; - calculates for each of the other relay nodes, called slaves, a phase shift (Acp ) Resulting from the difference between the measured phase for the slave relay node considered and the measured phase for the master relay node, and, - transmits the calculated phase shift to the corresponding slave relay node in an adjustment message transmitted in a slot of dedicated adjustment (S4) of the frame, and wherein a relay node (12) having received an adjustment message adjusts a phase of its transmitting-receiving means so as to cancel the phase shift indicated in said message of adjustment.
    [0006]
    6. A method according to claim 5, wherein each relay node (12) is adapted to calculate a frequency drift of its transmission-reception means from the phase shift contained in a succession of adjustment messages transmitted by a same receiving node (13) and adjusting the frequency of its transmitting-receiving means to correct said frequency drift, at least during the relay communication slot (S3) for transmitting a message of relaying communication to said destination node. 5
    [0007]
    The method of claim 1 or claim 2, wherein, the characteristic magnitude being a communication quality along an elementary path, the predetermined criterion is to verify that the characteristic magnitude of the elementary path between the source node ( 10) and the destination node (13), via the first relay node (11), which is the relay node indicated by the routing table, is greater than the characteristic magnitude of the elementary path between the source node (10) and the destination node (13), via the second relay node (12), the step of using the second relay node of relaying the payload data to the destination node (13) only by the second relay node (12), in substitution of the first relay node (11). 15
    [0008]
    8. An ad hoc network (1) comprising a plurality of nodes adapted to receive and transmit data messages and communicating with each other by sending signals in time slots arranged in frames, characterized in that each node comprises means for carrying out the method (90) according to any one of the preceding claims. 20
    [0009]
    9. The network of claim 8, wherein the frames comprise: a signaling slot (Si), allowing each node to transmit a signaling signal comprising signaling information, the signaling information allowing each node to determining its rank one neighboring nodes, link quality with each of its rank one neighboring nodes, its rank two neighboring nodes, and link quality between each rank one node and rank two node; A source communication slot (S2), enabling a node operating as a source node to transmit a source communication message to a rank node 30 operating as a relay node, the source communication message comprising the data useful to transmit to a final recipient; A relay communication slot (S3), enabling a node operating as a relay node to transmit a relay communication message to a destination node, the relay communication message comprising a header portion incorporating a pattern, a characteristic the transmitting relay node, allowing the destination node to calculate a phase of the signal corresponding to the relay communication message, and a payload portion including the payload data to be relayed to the destination node; and, - an adjustment slot (S4), allowing the node operating as a destination node to transmit an adjustment message to a relay node of a set of relay nodes used in a beamforming mode, the adjustment message having a phase shift.
    [0010]
    A network according to claim 8 or claim 9, wherein each destination node (13) of a plurality of relay communication messages transmitted by relay nodes (11, 12) of a set of relay nodes used in a beamforming mode, is adapted to calculate a phase (p) for each of said relay nodes from the signal corresponding to the incident relay communication message, to determine a phase shift between at least two of said relay nodes and to transmit the calculated phase shift at one of said at least two relay nodes, in an adjustment message transmitted in a dedicated adjustment slot (S4) of the frame.
    [0011]
    11. The network of claim 10, wherein each node operating as a relay node is capable of estimating a frequency drift of its transmitting-receiving means from the phase shift contained in a succession of adjustment messages transmitted by a transmitter. same destination node (13) and adjust its transmission-reception means to correct said drift.
    [0012]
    A network according to any of claims 8 to 11, wherein the routing table of a node comprises, for each recipient (15) of payload, the node of rank one of the node concerned and the node rank two neighbor of the considered node along the routing path.
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    同族专利:
    公开号 | 公开日
    US10341935B2|2019-07-02|
    FR3037462B1|2017-07-21|
    EP3104534A1|2016-12-14|
    US20160366634A1|2016-12-15|
    SG10201604808RA|2017-01-27|
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    2016-12-16| PLSC| Publication of the preliminary search report|Effective date: 20161216 |
    2017-06-30| PLFP| Fee payment|Year of fee payment: 3 |
    2018-06-27| PLFP| Fee payment|Year of fee payment: 4 |
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    优先权:
    申请号 | 申请日 | 专利标题
    FR1501223A|FR3037462B1|2015-06-12|2015-06-12|METHOD FOR LOCALLY CORRECTING THE ROUTING PATH IN AN AD HOC NETWORK AND AD HOC NETWORK THEREFOR|FR1501223A| FR3037462B1|2015-06-12|2015-06-12|METHOD FOR LOCALLY CORRECTING THE ROUTING PATH IN AN AD HOC NETWORK AND AD HOC NETWORK THEREFOR|
    US15/179,471| US10341935B2|2015-06-12|2016-06-10|Method for correcting locally the routing path in an ad hoc network and corresponding ad hoc network|
    SG10201604808RA| SG10201604808RA|2015-06-12|2016-06-13|Method for correcting locally the routing path in an ad hoc network and corresponding ad hoc network|
    EP16174245.7A| EP3104534A1|2015-06-12|2016-06-13|Method for correcting locally the routing path in an ad hoc network and corresponding ad hoc network|
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