Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L45/00—Routing or path finding of packets in data switching networks
  • H04L45/02—Topology update or discovery
  • H04L45/04—Interdomain routing, e.g. hierarchical routing
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L45/00—Routing or path finding of packets in data switching networks
  • H04L45/26—Route discovery packet
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L45/00—Routing or path finding of packets in data switching networks
  • H04L45/46—Cluster building
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
  • H04W4/06—Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
  • H04W88/02—Terminal devices
  • H04W88/04—Terminal devices adapted for relaying to or from another terminal or user

Definitions

• the present invention relates to a method for routing data in a network comprising nodes organized in groups.
• the organization of the nodes of a network in groups is particularly necessary in the case of an ad-hoc multi-hop mobile network, that is to say a network having no predetermined infrastructure, in which one does not has moreover only a limited bandwidth and in which the nodes are potentially mobile.
• a large-scale ad-hoc network that is to say an ad hoc network comprising a large number of nodes, for example more than a hundred nodes
• a data routing method in a network comprising nodes organized in groups, between a source node and a destination node respectively belonging to separate source and destination groups, the network comprising intermediate groups forming at least two potential data transmission paths through which the data may be transmitted.
• transmission potential path is a set of intermediate groups through which the data can be transmitted to reach the destination node.
• the potential path through which the data is actually transmitted will be called the "transmission path”.
• adjacent nodes two nodes that can communicate with each other without passing through an intermediate node.
• the method of the state of the art generally provides for taking into account parameters such as the quality of transmission between adjacent nodes through which the data are transmitted, as well as the quality. nodes themselves, typically estimating the delay and the rate of transmission between two nodes. However, it is difficult to reliably estimate these parameters for all nodes of a large-scale ad-hoc network.
• the invention proposes in particular to overcome this disadvantage by providing a routing method ensuring good quality of data transmission, and this efficiently and reliably, even in a large-scale ad-hoc network.
• an object of the invention is a method for routing data in a network comprising nodes organized in groups, between source and destination nodes respectively belonging to distinct source and destination groups, the network comprising intermediate groups forming at least two potential data transmission paths through which the data are likely to be transmitted, characterized in that it comprises:
• a determination step for each group of nodes of the network, comprising the reassembly by the nodes of the information group for the determination of a quality level, representing the quality of the data transmission through this grouping,
• a routing method according to the invention may further include one or more of the following features.
• the selection step is performed locally by a so-called local group through which the data are transmitted. This step comprising the choice, between several neighboring groupings of the local group through which the data are likely to be transmitted, of the group whose quality level is the best.
• the first local grouping is the source group.
• the data are transmitted step by step, each selected group becoming in turn the local group to transmit the data iteratively.
• each intermediate group is chosen by simple comparison of the levels of qualities of neighboring groups to the local grouping.
• a method according to this embodiment of the invention is particularly simple to implement.
• the method comprises a step of distributing, from each grouping to its neighboring groups, information containing the quality level of this grouping.
• each local group knows the quality levels of its neighboring groupings, which favors the choice of the intermediate group through which the data will be transmitted.
• the method includes a step of sending, by the source node to the destination node, a routing request, and a response step, by the destination node, the response comprising the quality levels of all the intermediate groupings through which the response is transmitted as well as the quality levels of their neighboring groupings.
• the source node obtains information to select the transmission path.
• the choice stage is carried out globally so as to choose at once the transmission path among all the potential paths, by favoring groups whose quality levels are the best. Thus, it is possible to choose an optimal path to obtain the best quality of transmission possible.
• the method comprises a step of distributing, from each grouping to all the other groupings of the network, the quality level of the grouping, of a local topology table comprising information concerning the location of the nodes within the grouping, and a partial global topology table, comprising information concerning the locations of neighboring groups of this grouping.
• the source group knows the quality levels of all the potential intermediate groups, which favors the choice of the optimal transmission path by which the data will be transmitted.
• this step can be renewed at least once, preferably regularly, so that each node maintains the topology local and partial topology tables.
• the method comprises a preliminary step of selecting, for each grouping, a master node from among the nodes of the group, the master node being intended to ensure the organization and maintenance of the grouping of nodes to which it belongs, in particular by acting as a bridge between this group and the other nodes of the network.
• the election of master nodes simplifies the organization of network nodes into groups. Each master node represents the grouping it belongs to the other master nodes, the master nodes communicating with each other to maintain the topology tables and to provide the source node with a transmission path between this source node and a node. destination in another group.
• the step of determining the quality level of each grouping comprises a calculation taking into account at least one parameter chosen from a connectivity parameter of the group, measuring the links between the group and the rest of the network, a group load parameter depending on the volume of data sent or transmitted by the nodes of the group over a predetermined period of time, a group stability parameter, depending on the number of transmission failures through this group over a predetermined duration, and a parameter group size, depending on the number of nodes in the grouping.
• the step of determining the quality levels is renewed at least once, for example periodically renewed.
• the ad-hoc network generally evolves over time, because of the mobility of nodes, it is best to update the quality levels of the groups regularly.
• the grouping in which the break has occurred performs a new path search to the destination node by repeating a sending step, by the node in which the transmission break occurred to the destination node.
• reliable transmission of data to destination is promoted.
• Another object of the invention is a network of nodes organized in groups, characterized in that it comprises, for each grouping, means for determining a quality level, representing the quality of the transmission of the data through this network. grouping, from the feedback of information by the nodes of the grouping, and means of choice of at least one intermediate group, for the purpose of transmitting data between source and destination nodes through the selected intermediate grouping, means of choice being adapted so that the choice is made according to the quality levels of the groupings of the network.
• the invention also relates to a grouping of nodes, characterized in that, by calling a neighboring group of the group, a group comprising at least one node adjacent to at least one node of the grouping, the group comprises:
• the invention finally relates to a computer program, characterized in that it comprises software instructions for implementing a routing method as defined above.
• FIG. 1 represents a network of nodes according to the invention.
• FIG. 2 represents the steps of a routing method implemented in the network of FIG. 1 according to a first embodiment of the invention.
• FIG. 3 represents the steps of a routing method implemented in the network of FIG. 1 according to a second embodiment of the invention.
• FIG. 1 shows a network of nodes, for example an ad-hoc network, designated by the general reference 10.
• the network 10 comprises potentially mobile nodes 12, 12M, 12S, 12D linked together by links 14.
• the nodes 12 are wireless communication devices communicating with each other using radio waves, electromagnetic waves or acoustic waves (such as ultrasound), and sharing a common broadcast channel.
• the nodes 12 may be mobile terminals, such as laptops, PDAs (Personal Digital Assistant), mobile phones, etc.
• the links 14 are cables in the case of a conventional wired network, or virtual links, such as radio links, in the case of a wireless network such as an ad-hoc mobile network.
• a link 14 between two nodes means that at least one of the nodes is in the coverage area of the other node, and therefore this node is likely to send data to the other node.
• the nodes 12 are organized in groups 16, 16S, 16D, 16A, 16B, 16C, 16E, 16F in a conventional manner.
• Each group 16 comprises a node intended to represent this group 16 in the network 10, said master node 12M.
• the master node 12M is intended to ensure the organization and maintenance of the node grouping to which it belongs, in particular by acting as a bridge between this group 16 and the other nodes 12 of the network 10.
• FIG. 2 shows the steps of a routing method according to a first embodiment of the invention.
• the method comprises a preliminary step 100 for organizing the nodes 12 into groups 16, and selecting, for each group 16, a master node 12M intended to represent this grouping in the network 10.
• This step is conventional and usually used to facilitate the routing of data in an ad-hoc network.
• the preliminary step 100 may include assigning, at each node 12 of the network 10, a numerical value, called weight, representing its capacity to to be a master node.
• weight representing its capacity to to be a master node.
• Each node 12 whose weight is greater than the weight of all its adjacent nodes is then elected master node 12M of a group comprising this master node 12M and all its adjacent nodes.
• the organization of the nodes 12 in groups 16 can be carried out in any other known manner.
• the groups 16 may comprise any number of nodes 12, this number depending in particular on the way in which the node organization step is implemented.
• step 1 10 establishment of topological tables of the network.
• a local topological table is established, comprising a list of all the nodes 12 of this group 16 and accounting for the way in which these nodes 12 are organized in this group 16.
• the master node 12M of this group sends a location request to all the other nodes 12 of the group. These other nodes 12 respond after having received this request, by returning to the master node 12M location information enabling the master node 12M to establish the local topology table.
• each grouping 16 initially performs a search for its neighboring groupings, that is to say the groupings comprising at least one node adjacent to one of the nodes of the group.
• This search can be performed for example as follows:
• the master node 12M of each group 16 generates a search request for neighboring groups, and broadcasts this request,
• this node 12 responds by sending to the master node 12M a message comprising the identifier of its own master node and information on the path traveled by the request, for example an identifier of the node that transmitted the request,
• the master node 12M uses the responses received, updates a partial global topological table, including information on the location of its neighboring groups. Thanks to the local and partial global topological tables, each master node can learn, by simple consultation of these topological tables, which are the nodes 12 of its grouping 16, and which are the neighboring groups to its grouping 16.
• steps 100 of organization of the nodes and 1 of establishment of the topological tables are preferably renewed regularly, for example periodically with a predetermined period T, in order to take into account the mobility of the nodes 12 of the network 10.
• the routing method then comprises a step 120 for determining, for each group 16, a numerical value, called quality level, representing the general quality of the data transmission through this grouping 16.
• quality level a numerical value representing the general quality of the data transmission through this grouping 16.
• each node master is provided with means for determining a level of quality.
• the master node 12M of each group 16 sends an information request to the other nodes 12 of this group 16, which respond by sending back to this master node 12M information for the group. calculation of parameters that will be used for the determination of the quality level.
• the request also generally includes a numerical value corresponding to a time interval I after which the nodes return the information again, for an update of the quality level.
• This time interval I depends, for example, on the dynamics of the network (high in a stable network, running in a network whose nodes are particularly mobile).
• this time interval I is equal to the renewal period T of the node organization steps 100 and the topology establishment step 100.
• a first possible parameter is a group connectivity parameter P c , measuring the links between the group 16 and the rest of the network 10. Indeed, the more a group 16 is served by a large number of neighboring groups, the more it can be effective for transferring data.
• the connectivity parameter P c can be calculated as follows:
• n BN is the number of border nodes of the group 16, that is to say the number of nodes of the group which are adjacent to nodes belonging to neighboring groups
• V BN is the number of border nodes belonging to a neighboring group which are linked to a border node of the grouping 16.
• a second possible parameter is a charge parameter P CH of the group, depending on the number of packets sent or transmitted by the nodes 12 of the group 16 during a predetermined duration.
• P CH charge parameter
• Such a parameter gives a measurement of the activity of the group 16.
• the predetermined duration is for example equal to the time interval I.
• the load parameter can be calculated as follows:
• Xi is the packet rate passing through a node i of the array 16 for the predetermined duration.
• N is the number of nodes of the grouping 16.
• a third possible parameter is a parameter P s of stability of the group 16, depending on the number of transmission failures through this group 16 during a predetermined duration, for example equal to the time interval I.
• the parameter stability P s can be calculated as follows: or
• T E is the number of transmissions that have failed transmission in the group for the predetermined duration.
• T 1 . is the total number of transmissions that have been made by the group for the predetermined duration.
• a fourth possible parameter is a parameter P 1 . size of the group 16, depending on the number of nodes 12 belonging to the group 16.
• the parameters defined above are adapted to effectively represent the quality of the group 16, but the person skilled in the art implementing the invention may of course take into account other parameters, in addition to or in place of one or more of the aforementioned parameters, for the calculation of the quality level of a grouping.
• certain parameters may be more or less relevant depending on the desired application and the organization of the network. For example, in the case where all the groups 16 have a substantially identical number of nodes 12, it would not be necessary to take into account the size parameter P 1 . in the calculation of the quality level. Those skilled in the art will be able to choose the relevant parameters for the calculation of the quality level, as well as their possible weight to be taken into account in the calculation.
• each master node 12M is provided with means for storing the quality level.
• the determination step 120 is preferably renewed regularly, for example periodically with a period equal to the time interval I, in order to take account of the changes in the network due to the mobility of the nodes 12 of the network 10.
• the method then comprises a step 130 of broadcasting information from each group 16 to its neighboring groups, this information being transferred from the master node to the master node.
• the information broadcast by a grouping 16 includes the quality level of this grouping 16 as well as its local topological table, and in some cases its partial global topological table.
• This diffusion step 130 may be renewed regularly, for example periodically, in order to update the information when changes occur in the groupings (for example when a node enters or leaves a group).
• the renewal period of the diffusion step 130 is equal to the period T of renewal of the steps 100 of organization of the nodes and 1 of the establishment of the topological tables.
• a step 140 of sending a routing request of this source node is carried out 12S to this destination node 12D.
• the master node 12M of the source group 16S verifies, with the aid of its local topological table, that the destination node 12D does not part of the group to which it belongs, in which case it would suffice to transmit the data in a conventional manner.
• the master node 12M conventionally sends the routing request to its neighboring groupings.
• This routing request comprises in particular respective identifiers of the source node 12S and the destination node 12D.
• a master node 12M When a master node 12M receives the request, it checks, using its local topology table, if the destination node 12D is part of its grouping.
• each group 16 since each group 16 has diffused its partial global topological table during step 130 to its neighboring groups, they know which are the other neighboring groups of this group 16. Thus, it can be provided that a grouping does not transfer the request to the other neighboring groupings of the group which transmitted this request to him, since these neighboring groups have already received this request, at the same time as him. This avoids superfluous transmissions that would clog the network.
• the grouping 16B after having received the request from the source group 16S, transfers this request to the groupings 16C and
• a response step 150 is started, during which the master node 12M of this group 16D sends a response to the source node 12S by the reverse path of the one traveled by the routing request.
• grouping 16D considers only the first routing request received, and ignores the identical routing requests reaching it after the first, by another path.
• the request can reach the destination group 16D via the following of groups 16B, 16F or subsequently of groups 16A, 16E, or subsequently of groups 16A, 16F.
• the destination group 16D will only consider the first request received, for example that passed through the groups 16B, 16F.
• the response comprises the identifiers of the intermediate groups forming the transmitted transmission path, as well as information from the topological local and partial topological tables, and information on the quality levels of each of these intermediate groups. For this purpose, each intermediate group transferring this response adds information about it before transferring it.
• the source node 12S receives information (topological tables and quality levels) concerning a potential path of transmission to the destination node, in particular, for each grouping 16 of the transmission path, information concerning this grouping 16 and information concerning its contents. neighboring groups.
• the source node 12S When the source node 12S has received the response, it proceeds to a step 160 of sending, by this source node 12S, data to be transmitted to the destination node 12D.
• the transmission step 160 is also a step of choosing a transmission path.
• each master node 12M is provided with means for selecting an intermediate group to form the transmission path.
• the intermediate groups forming the transmission path are chosen from the intermediate groups forming the potential path received in the routing response and the neighboring groups to these intermediate groups.
• the path is then chosen step by step, a local group to transfer the data choosing the next intermediate group as follows.
• the first grouping of this path received according to the local grouping is not necessarily the one whose level of quality is the best to reach the second grouping of the path received. following the local grouping.
• the group therefore seeks to reach this second grouping of the path received following the local grouping, via a common neighboring group whose quality level is better than that of other common neighboring groups.
• the data are thus transmitted step by step, the first local group being the source group, then each selected intermediate group becoming the local group, until the local group is a neighbor of the group. group with the destination node, in which case it directly transmits the data in a conventional manner.
• the source group directly transmits the data to the destination group in a conventional manner.
• the second grouping of the path received following the local grouping (currently the source group) 16S is the group 16F. .
• the source group 16S transmits the data.
• the grouping 16A then becomes the local grouping.
• the second grouping of the path received according to the local grouping 16A is then the destination group 16D.
• the grouping 16A then transmits the data to the grouping 16E, which becomes the local grouping. Then, since this grouping 16E is adjacent to the destination group 16D, it directly transmits the data in a conventional manner.
• the data transmission takes place from node to node, for example by privileging the nodes of better transmission qualities in a conventional manner.
• the local group in which the error occurred attempts to send the data back to the destination node 12D, for example by determining a new transmission path by repeating the process as if this local grouping was a source grouping.
• This first embodiment of the invention has the advantage of being simple to implement, the choice of intermediate groups through which the data are transmitted being achieved by simple comparisons of quality levels.
• FIG. 3 shows the steps of a routing method according to a second embodiment of the invention. This method comprises a preliminary stage 200 of organization of the nodes
• a step 210 of establishing topological tables of the network and a step 220 for determining, for each group of nodes of the network, a quality level, these steps being similar, respectively, to steps 100, 1 and 10 of the first embodiment of the invention.
• the step 210 of establishing topological tables differs from step 1 of the first embodiment in that it further comprises the diffusion, by each grouping, of its partial global topological table to all the other groups of the network, the set of partial tables thus obtained by each grouping to establish a global topological table of the network, reporting the organization of all groupings 16 of the network 10 between them.
• the method then comprises a step 230 of broadcasting information from each group 16 to all the other groups of the network 10.
• each group 16 has global information concerning the network 10 as a whole.
• each master node has a quality matrix, representing the quality levels of all the groupings 16 of the network 10, and of the global topology table of the network 10.
• the master node of the source group 16S can choose at one time an optimal transmission path using the information obtained during step 230, in focusing on groups with the highest quality levels.
• the source node sends the data to the destination node using the chosen transmission path.
• the data transmission takes place from node to node, for example by privileging the nodes of better transmission qualities in a conventional manner.
• This second embodiment of the invention has the advantage of allowing the choice of an optimal transmission path, for which the transmission quality is the best possible.

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• 2007
  • 2007-08-28 EP EP07823746A patent/EP2057807A1/de not_active Withdrawn
  • 2007-08-28 US US12/439,635 patent/US20100011244A1/en not_active Abandoned
  • 2007-08-28 WO PCT/FR2007/051847 patent/WO2008025925A1/fr active Application Filing

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