WO2009007619A2 - Wireless ip mesh network - Google Patents

Abstract

The invention relates to a wireless IP network structured into groups comprising, for at least one group, a plurality of base stations interconnected in mesh mode and initially connected to the group and mobile equipment initially connected to a parent base station from among the base stations of the group. An initial IP address is allocated to the devices among the base stations and the mobile equipment, said IP address comprising an identifier indicating the group and, if necessary, the parent base station to which the device is initially connected. If said connection is changed, a temporary IP address is allocated to the device, said temporary IP address including an identifier indicating the group and, if necessary, the parent base station to which the device is currently connected. The network includes means for matching the initial and temporary IP addresses, for example, in order to transfer messages to the device.

Description

 NETWORK IP WIRELESS MESH

The invention relates to the field of wireless meshed IP networks, for example but not limited to WiMAX networks compliant with the specifications of the IEEE 802.16 standard.

Such networks are structured in groups ("clusters" in English), each group comprising several base stations connected to each other in mesh mode, and mobile devices, for example access points or terminals. The terminals may include laptops, PDAs (Personal Digital Assistant), etc. Each piece of equipment is initially attached to a parent base station among the group's base stations. When an equipment wishes to communicate with another equipment, or to access an Internet core network for example, it sends a message, for example a WiFi or WiMAX message, received by the mother station, either directly or by the intermediate of an access point. The mother station then communicates with the mother station of the other equipment or with a station wired with the Internet. Communication can thus be established.

Such a network is for example described in the document "Affordable Infrastructure for Deploying WiMAX Systems" by V. Gunasekaran and F. Harmantzis, Stevens Institute of Technology, Telecommunications Management, USA, IEEE 2005.

However, network devices, ie mobile devices and stations, are likely to be detached from the parent base station or the group at any time. For example, a device may be moved some distance from its home station, so that messages from that equipment may be received by another station than the home station and messages to that moved equipment may to be lost. In another example, a base station can leave one group and join another group, for example following a change of frequency, so that again communications with this station may be disorganized.

The invention makes it possible to ensure correct routing of the messages, even in case of change of attachment. According to a first aspect, the invention relates to a mobility management method in a group-structured wireless IP network, the network comprising for at least one group, a plurality of base stations connected in mesh mode, and equipment each mobile equipment is initially attached to a parent base station among the base stations of the group. At least one of the base stations and the mobile devices is assigned an initial IP address comprising at least one identifier of the group to which said device is initially attached. If the device is a mobile device, it is considered that the group to which the device is initially attached is the group to which the parent station to which the device is initially attached is initially attached. If applicable, that is to say if the device is a mobile device, the initial IP address further comprises an identifier of the parent base station to which this device is initially attached. The method comprises the steps of, in the case of a change of attachment of said device to the parent base station and / or the group, assigning a temporary IP address to said device, said temporary IP address including at least one identifier of the group to which said device is now attached and, if necessary, an identifier of the base station to which said device is now attached, and match the initial IP address with the temporary IP address, in particular to transfer messages to the device.

This method thus makes it possible to maintain the communications within the network, despite possible changes in the attachment of mobile equipment and base stations. This method may for example be implemented, in whole or in part, by a base station, a core base station associated with a group, and / or by a central server managing a set of groups. Thus, if a device - base station or mobile equipment - changes of attachment, the group and if necessary the mother station initially corresponding to this device can (wind) be determined (s) from the initial IP address of this device. device. The assignment of a temporary IP address and the mapping of the two addresses allow a correct routing of the messages intended for this device.

For example, if a piece of equipment has been moved so that the nearest base station is different from the parent station of that piece of equipment, the address of the mother station to which that piece of equipment is initially attached from the original station can be found. initial IP address, also called mother IP address, of the equipment, even if the equipment has changed group. A message to the initial address of this mobile device may, because of the means of correspondence, be routed taking into account the temporary address. This temporary IP address of the mobile equipment includes identifiers of the station to which the equipment is now attached and of the group to which the equipment now belongs, so that the message to the temporary address normally arrives at the station to which the mobile equipment is now attached, which can then forward the message to the equipment.

According to another example, if a base station has changed group, it is possible to find the IP address of the group to which this station was initially attached from the initial IP address of this base station. The assignment of a temporary IP address and the mapping of the two IP addresses makes it possible to guarantee a correct routing of the messages intended for this base station.

Advantageously, each given device among the mobile devices and the stations has an initial IP address comprising an identifier of the group to which the given device is initially attached and if necessary an identifier of the mother station to which this device is initially attached. In other words, addressing within the IP network is hierarchical.

The assignment of an IP address to a given device of the network is thus relatively simple, since it is sufficient to refer to the higher level direct, for example for equipment, the mother station corresponding to this equipment.

Advantageously, during the mapping step, the initial IP address is analyzed to seek to determine the group and, if applicable, the mother base station to which the device is initially attached. A message including the initial and temporary addresses is sent to a chosen network installation according to the result of the analysis. This analysis, this choice and / or this shipment can be performed by a base station, a core station associated with the group and / or by a central server for example. These steps are intended to communicate to the group and if necessary to the mother base station to which the device is initially attached the temporary address of the device.

The invention is in no way limited by the practical implementation of the mapping between the IP addresses. For example, it may be provided that a first installation, for example a base station, performs the assignment of the temporary address, then, as a mapping, simply sends a message including both addresses to a second installation, for example a server, which analyzes the initial IP address in order to find the initial connections of the device.

Advantageously, if the analysis of the initial IP address leads to a non-determination of the initial connections of the device, the message comprising the two addresses of this device is sent to a central server managing a set of groups. The central server can indeed be able to determine the initial connections of the device.

The method which is the subject of the invention can be implemented by a base station which has detected moving equipment moved. In this case, it can for example be provided that in case of non-determination, the message sent to the central server passes through the core station of the group.

It can further be provided that, in the event of determination of the initial connections of the device, the message is sent to a core base station associated with the group thus determined and / or to the mother station. thus determined where appropriate. The mother station and / or the core station of the group can thus be notified of the change of attachment, so that communications with this device can be relayed. For example, a Mobile IP Proxy protocol can be used to handle possible device attachment changes.

The analysis step of the initial IP address can be performed for example by a base station, a core base station or even by a central server.

If it is a heart station that performs the analysis step, the initial IP address can for example be received from a base station in communication with a moved equipment. The heart station memorizes for example a list of the IP addresses of the stations of the group and uses this list to seek to determine the mother station. In case of failure, the message containing the initial IP address is sent to the central server. If successful, the heart station sends the message to the mother station thus determined, so as to allow a relay of communications with the moved equipment.

If it is a central server that performs the analysis step, the server may, for example, have received the initial IP address of a moved device following a non-determination of the initial connections of this equipment by the base stations. and heart for example. Alternatively, the base stations and the heart refrain from analyzing the initial IP address and simply transmit this IP address to the central server. In any case, the central server can memorize the IP addresses of a certain number of devices, typically the IP addresses of the stations of the groups it manages, and can therefore be able to determine the IP address of the mother station for the equipment moved.

The central server can send the message containing the initial IP address and the temporary IP address of the moved equipment to this mother station, in order to allow communication management with this moved equipment.

Advantageously, the method comprises a dynamic update of a routing table storing the topology of the mesh network formed by the stations of the group. The contents of this table are used for communications within the mesh network. Thus, the routing between these stations is able to adapt to changes in the mesh network, such as a station failure, the addition of a new station, and so on. For example, it may be possible to use an OLSR protocol

"Optimized Link State Routing Protocol").

Of course, the invention is in no way limited by the adoption of such a protocol.

According to another aspect, the subject of the invention is a wireless IP network structured in groups, the wireless IP network comprising, for at least one group, a plurality of base stations connected to each other in mesh mode and initially attached to each other. to this group, and mobile equipment, each mobile equipment being initially attached to a parent base station among the group's base stations. At least one of the base stations and the mobile devices is assigned an initial IP address comprising at least one identifier of the group to which this device is initially attached, and, if applicable, an identifier of the mother base station to which said device is initially attached. In case of a change of attachment of this device to the mother base station and / or the group, a temporary IP address is assigned to this device, this temporary IP address including at least one identifier of the group to which this device is now attached and , if applicable, an identifier of the parent base station to which this device is now attached. The network comprises means for matching the initial IP address and the temporary IP address in particular for transferring messages to the device.

This network can be used for the implementation of the method according to one aspect of the invention.

The wireless IP network is hierarchical in levels. The fact that a device is attached to another device, called attachment point ("anchor point" or "attachment point" in English), means that communications between levels with this device pass through this point of attachment. For example, the messages conveyed by the mesh network formed by the base stations of a group, which are destined for or from mobile equipment, pass through the base station to which this mobile equipment is attached. In another example, the messages from a device of a group and to a device of another group pass through base stations hearts of each of these groups. That is, the fact that a base station is attached to a group causes communications between distinct groups with that station to pass through the core base station associated with the group to which the base station is attached. Initial attachments are typically set up during an initialization phase, for example following the purchase of new equipment.

In case of successive changes of attachment, the temporary address can be replaced by a new temporary address, this new temporary address then being matched with the initial address.

According to another aspect, the subject of the invention is a computer program intended to be stored in a memory of a device for a wireless mesh IP network as described above, for example a base station or a server. central, or stored on a storage medium for cooperating with a reader of this device and / or downloaded via a telecommunications network. This program includes instructions for performing the steps of the method described above.

According to another aspect, the subject of the invention is a base station intended for a group-structured wireless IP network, the station being arranged to be attached to a group, for attaching to itself mobile devices, and for to be connected in mesh mode to a plurality of other base stations also attached to said group. IP address allocation means are used to assign to the mobile equipment attached to said base station an IP address comprising an identifier of said station and an identifier of the group to which said station is attached.

This station thus makes it possible to assign an IP address to the mobile equipment attached to it, either initially or following a change of attachment, eg due to displacement, frequency change, etc. The IP address thus allocated is such that it is possible to find the initial or present connections of the equipment.

Advantageously, the base station further comprises reception means for receiving a message from a mobile device initially attached to another base station and having an initial IP address, processing means for analyzing this initial IP address in order to seek determining the group and the base station to which said mobile equipment is initially attached, and sending means for sending to a wireless IP network installation the initial IP address and a temporary IP address assigned to said mobile equipment by said station , said installation being chosen by the processing means according to a result of the analysis.

Of course, the base station is not limited by the presence of these means.

Advantageously, it can be provided that the stations of a given group, connected to each other in a mesh mode, each comprise a routing table for storing the topology of the mesh network formed by the stations of the group, as well as means for updating to dynamically update said routing table. Communication means may be able to transmit messages to at least one other station of the mesh network, based on the content of the routing table.

In another aspect, the invention relates to a central server for a wireless IP network mesh as described above. The central server comprises means for receiving a first message comprising an initial IP address and a temporary IP address of the same device from the base stations and the mobile devices of the network, processing means for determining from the initial IP address the group to which the device is initially attached and where appropriate the mother base station to which the device is initially attached, and sending means for sending to a base station core of the group determined by the means of treatment and / or where appropriate to the mother station determined by the means processing a second message including the initial IP address and the temporary IP address.

This central server is thus able to determine the initial connections of a device having changed connections, and to prevent the relevant facilities to ensure proper routing of messages to this device.

"Mobile equipment" means any equipment that can be attached directly or indirectly to a base station. Mobile equipment indirectly attached to a base station can for example be directly attached to an access point, this access point being itself attached to this base station. A so-called mobile equipment may be able to be moved without it being necessary to assign a new initial IP address, (equipment of the portable computer type, PDA, etc.). The mobile equipment can therefore remain at a fixed position, if the user does not move it.

Changes in attachments may be due to displacement, but also to a change in frequency or other cause.

Other features and advantages of the present invention will become apparent from the description hereinafter.

Figure 1 shows an example of a wireless IP network according to one embodiment of the invention.

Figure 2 shows an exemplary device in a wireless IP network, according to an embodiment of the invention. FIG. 3 is an example of an algorithm executable by a device according to the embodiment of FIG. 2.

Figure 4 shows an exemplary device in a wireless IP network, according to one embodiment of the invention.

FIG. 5 is an example of an algorithm executable by a device according to the embodiment of FIG. 2.

Figure 6 shows an exemplary device in a wireless IP network, according to one embodiment of the invention. In the different figures, identical or similar objects may be designated by the same reference numerals.

Figure 1 shows an example of a wireless IP network according to one embodiment of the invention. In this example, it is a network managed by a WiMAX operator. A central server 20, for example a DHCP server (of the "Dynamic Host Configuration Protocol"), is wiredly connected to a core network 1, for example the Internet, on the one hand, and to base base stations 7. , T or CBS (of the English "Core Base Station") secondly. At each CBS 7, T is associated with a group 4, 5. Within each group 4, 5, the associated core base station 7, T is connected in mesh mode with meshed base stations 8, 8 'or MBS ( of the English "Mesh Base Station"). The MBSs 8, 8 'are each associated with a cell. Each MBS can initially attach one or more mobile devices 2, 3, AP0501, AP0301. Mobile devices may for example include AP0501 access points. AP0301 or CPEΞ / AP (of the English "Costumer Premise Equipment / Access Point"), and subscriber stations or SS (of the English "Subscriber station") as terminals 2, 3 of type laptop for example .

The stations CBSs and MBSs 7, 8, 7 ', 8' can for example comprise stations complying with the specifications of the IEEE 802.16 standard of 2004. Based on this standard, two modes of operation are supported: the PMP mode (of Point to Multi-Point) in which the transmission of traffic is between the base station and the subscriber station SS, and the mesh mode in which the transmission of the traffic can be carried out via subscriber stations. Intermediate SS who relay information to arrive at destination. In addition to the specifications of the IEEE 802.16 standard of 2004, a mesh network must be understood, according to the meaning given in this application, as supporting the mesh mode managing the communications between the base stations of the same group. The CBS and MBS stations of a given group form a multi-hop mesh network between the CBS and MBS stations, as shown by the dashed lines in Figure 1. The mobile equipment 2, 3 within the range of a given WiMAX cell communicate with the base station (MBS or CBS) corresponding to that cell. For example, the terminal 2, initially attached to the MBS1 station, is connected by WiFi technology, for example, to AP05 access point ₀ 1 which provides the connection to the MBS1 station via WiMAX technology. The terminal 3, initially attached to the MBS1 station, is in this example directly connected to the MBS1 station with WiMAX technology.

In this wireless IP network, the addressing is hierarchical. For each given device among the mobile devices 2, 3 and the MBS stations, the IP address of the higher level device to which the given device is initially attached can be determined from the initial IP address of the given device.

MBS base stations have initial IP addresses with an identifier of the group to which they belong, that is, an identifier of the CBS to which these MBSs are initially attached. For example, the core station CBS1 has the initial IP address 192.00.00.00 and the MBS initially attached to the group associated with this CBS have initial IP addresses that start with 192, such as 192.05.00.00 or 192.03.00.00. Thus, if one of these MBSs changes group, the first three digits of its initial IP address indicate the CBS to which this CBS was initially connected.

Each mobile device has an initial IP address such that the initial IP address of the MBS to which this equipment is initially attached is determinable from the initial IP address of the equipment. For example, the access points AP0501, AP0301 have initial IP addresses 192.05.01.00 and 192.03.01.00 respectively. The first five digits are used to determine the MSBs to which these access points are initially attached. The addresses of the terminals 2, 3 also obey such an addressing scheme. For example, the terminal 2 attached to the AP0501 access point has the initial IP address 192.05.01.01: the first seven digits are used to find the access point initially connected to this terminal, the first five digits make it possible to find the MBS initially attached to this terminal and the first three digits make it possible to find the group to which the terminal initially belongs. The sixth and seventh digits constitute an identifier of this access point, the fourth and fifth digits constitute an identifier of this MBS and the first three digits constitute an identifier of this group.

Terminals directly attached to station MBS1, such as terminal 3, may have IP addresses of type 192.05.04.00,

192.05.04.01, 192.05.04.02 etc. In other words, IP addresses of type 192.05.04.xx are reserved for terminals directly attached to the station

MBS1.

Figure 2 shows a part of the network of Figure 1, except that the terminals 2, 3 have been moved from one cell to another within the same group. FIG. 3 is a flowchart of a method executable by the station 21 of FIG. 2. These two figures are therefore commented simultaneously.

The terminals 2, 3, initially attached to the station MBS1, are now closer to the meshed base station 21. The messages transmitted by the terminal 3 are therefore detected by receiving means 23, for example a processor 23 programmed to receive messages from station 21 (step 30 in Figure 3). These messages include the initial IP address & 1 of the transmitter, namely the terminal 3.

The station 21 can be considered as foreign agent or FA (of the English "Foreign Agent") for the equipment 3.

The station 21 comprises processing means 22, for example a processor, both for assigning a temporary IP address & 2 to the equipment 3 (steps 32 and 35 in FIG. 3) and analyzing the initial IP address & 1) in order to determine the mother station to which the terminal 3 is initially attached.

The temporary IP address can be called CoA (of the English "Care of Address"). In an alternative embodiment and not shown, the means for assigning the temporary IP address and the means for analyzing the initial IP address are distinct.

The initial and temporary IP addresses are mapped, for example by means of tables storing these two addresses, for example the LUAT tables described below, and by sending messages containing these two addresses to certain installations of the network, so that that these facilities are able to take into account the change of attachment when routing messages. In this example, the processing means 22 are arranged to perform a first test (step 31) as belonging to the group of the terminal 3. This test is performed from the initial IP address, for example from the three first digits of this IP address. If these first three digits are the same as the first three digits, the IP address of the station 21, then it is considered that the terminal 3 is initially attached to one of the stations of the group.

If this test 31 shows that the terminal 3 comes from the same group as the station 21, then the station 21 is normally able to determine the IP address of the mother station to which the terminal 3 is initially attached. The processor 22 is in fact connected to a table CSAT (Cluster Station's Addresses Table) memorizing the IP addresses 802.16 stations of the group. The processor 22 may for example search in a step 34 which station of the group has an IP address whose first five digits are identical with the first five digits of the initial IP address. This home station or HA (Home Agent) is normally the one to which the equipment 3 is initially connected.

The station 21 chooses in a step 35 a temporary IP address & 2 corresponding to the received address. This temporary IP address includes an identifier of the station 21 and an identifier of the group to which the station 21 belongs. Typically, this temporary IP address is generated by conforming to the same addressing scheme as for the initial IP addresses, described with reference to FIG. 1. From this temporary address, it is thus possible to find the cell in which the IP address is located. equipment moved 3. Station 21 may choose to assign the same temporary address to a plurality of moved equipment.

The processor 22 is further connected to a table LUAT (from the English

"Local User's Addresses Table") storing the IP addresses of the equipment present in the cell of the station 21. The processor updates this table in a step 36 by adding the initial and temporary IP addresses of the equipment 3.

Finally, sending means 24, for example a processor 24 programmed to prepare a message to be sent, make it possible to send a message comprising these two addresses to the HA station during a step 37. This message may be a message. registration request ("registration request" in English) thus signaling the movement of the terminal 3 from one cell to another.

The means 22, 23, 24, as well as the CSAT table thus participate in the search for the initial connections of the equipment 3 and therefore constitute, with in particular the updated tables (LUAT for example), matching means initial and temporary addresses.

The means 22, 23, 24 may alternatively be merged into the same processor. The HA station, here the MBS1 station, receives this request and updates its own LUAT table, adding to the initial IP address the temporary IP address received in the registration request message. Thus, if a message destined for the terminal 3 -comportant the initial IP address of this terminal, is received by the station MBS1, this station can, using its table LUAT, route this message to the station 21. The Station MBS1 can encapsulate the received message in another message carrying as the destination address the temporary address.

The core station CBS1 also receives, from the station 21 or from the station MBS1, a message comprising the two IP addresses of the terminal 3. The core station CBS1 is thus able to update an LMUAT table storing the initial and temporary IP addresses. moved equipment.

The LUAT table can be used in the case of Peer-to-Peer (P2P) communication between the MBSs of the same group (without passing by the CBS), while the LMUAT table is used in case the traffic is routed via the CBS.

For example, a Mobile IP Proxy protocol can be used to manage the movement of equipment from one cell to another. In the case of equipment indirectly connected to the station 21, such as the terminal 2 for example, the method implemented by the station 21 is the same, except that the receiving means 23 receive the IP address of the terminal 2 via an access point and not directly from the terminal 2.

If the test 31 of Figure 3 shows that the terminal 3 comes from another group, the station 21 is unable to determine the mother station to which the terminal 3 is initially attached. The station 21 chooses in a step 32 a temporary address & 2 and sends in a step 33 a request message to the heart station CBS1 to which the station 21 is attached. This sent message includes both the received IP address (or initial IP address) and the corresponding temporary address. The initial and temporary addresses are thus matched.

The core station CBS1 then transmits this message to the DHCP server 20. FIG. 5 is a flowchart of an exemplary method implemented by the DHCP server. Also, Figure 4 shows the wireless IP network of Figure 1, the terminal 3 being this time moved out of the group to which it originally belonged. Figures 4 and 5 are therefore commented simultaneously. The station MBS 20 receives in any message sent by the terminal 3 the initial IP address of the terminal 3, and performs the steps 31, 32, 33 of FIG. 3. The station CBS2 of the group of the station MBS20 transmits the transmitted message. by the MBS20 station to the DHCP server 20.

In an alternative embodiment and not shown, the role of the CBS2 station could not be limited to a simple transmission of messages. For example, it could be the CBS2 station that performs the steps of Figure 3.

The DHCP server 20 comprises reception means 43, for example a processor 43 programmed to receive messages, to receive the request message comprising the initial and temporarily during a step 50. The server 20 validates the reception of the request message during a step 51, then in a step 52 updates a GMUAT table storing the initial and temporary IP addresses of the moved equipment of one group to another. Processing means 42, for example a processor, make it possible to analyze the initial IP address received, in order to determine the mother station to which the terminal 3 was initially attached. The processor 42 can be connected to CSAT tables storing the IP addresses of the stations of the groups managed by the central server. During a step 53, these CSAT tables are consulted in order to find, from the initial IP address, the mother station corresponding to this terminal 3 or HA.

A registration reply message ("Registration Reply" in English) is then sent by means of sending 44 to the determined HA station MBS1, and to the CBS of this HA station. The station MBS1 can then update its table LUAT to take into account the displacement of the terminal 3 outside the cell associated with the station MBS1. The CBS1 station updates its LMUAT table storing the initial and temporary IP addresses of the moved devices.

The record response message is also sent as a confirmation to the CBS2 and MBS20 stations in a step 55.

Station MBS20 can be considered foreign agent or FA for equipment 3.

Again, a Mobile IP Proxy protocol can be implemented to manage communications with the moved equipment. 3. Communications between stations in the same group can be managed using an OLSR protocol. Each station thus comprises an OLSR table memorizing the topology of the mesh network formed by the stations of the group. Update means not shown, for example a processor programmed to take into account the signaling of failure or addition of stations and to write in the table these modifications, allow to dynamically update this routing table. Communication means not shown, for example a processor and a radio module, allow messages to be sent based on the content of this routing table.

For example, if a message is sent to the initial address of a moved device 3, either inside the group to which it originally belongs as in Figure 2, or outside that group as in Figure 4, this message arrives at the HA (the station CBS1) of the equipment 3, that is to say the station to which the equipment 3 is initially attached.

The station CBS1 consults its table LUAT to find the temporary address corresponding to the initial address, and returns this message, by encapsulating it in another message having this temporary address in the field of destination. The CBS1 station uses its OLSR table to determine the station to which to send this other message.

The OLSR protocol is therefore implemented to route the message sent by the CBS1 station, whether to the FA if it belongs to the same group or to the core station of the group if the FA belongs to another group. In the latter case, the message passes through the central server, then through the heart station of the other group to be relayed using the OLSR protocol to the FA station. The FA station therefore receives the message sent by the HA, consult its own LUAT table to determine whether it is necessary to decapsulate the received message. If the LUAT table includes the destination address of the message sent by the HA and a corresponding initial IP address, the FA station decapsulates the received message and sends a message obtained from the decapsulated message to the equipment 3 which is in the cell associated with the FA station.

This sequence of operations is of course only given as an example. The use of a protocol of the Proxy Mobile IP type thus makes it possible to guarantee communications with displaced mobile devices. If adding or deleting stations, for example due to a failure, the other stations can change the routes dynamically, without changing IP addresses. An update of the OLSR routing tables ensures the routing of traffic to each MBS. The use of the OLSR protocol thus makes it possible to guarantee the self-configuration of the MBSs in the same group.

FIG. 6 shows another example of a device, here a base station MBS1, in the wireless IP network of FIG. 1, except that station MBS1 has been attached to another group.

If the MBS1 base station joins another group by changing its frequency due to a loss of connectivity in its initial group, or even a rebalancing of loads between the groups, this station MSB1, initially attached to the station CBS1 7, now has another point of attachment, typically the CBS T station of the new group.

The station 7 'comprises unrepresented receiving means adapted to receive messages from the displaced station MBS1. Unrepresented processing means make it possible to analyze the destination IP & 1 address of a message received from the station MBS1, that is to say the initial IP address of the station MBS1. Station T consults its CSAT table to find that the received IP address does not match a station registered as belonging to the group, and assigns a temporary IP address & 2 to the moved station. This IP & 2 address includes an identifier of the visited group. Unrepresented sending means make it possible to send to the central server 20 a message comprising both IP & 1 and & 2 addresses. This sending helps to match these two IP addresses.

The central server 20 comprises unrepresented receiving means for receiving this message. The central server is connected to a GSART (Global Station Address Routing Table) which stores the initial and temporary IP addresses of the MBSs stations that change their point of attachment from one group to another. This GSART table is updated after receiving this message. In addition, unrepresented analysis means of the central server 20 make it possible to determine the station CBS 7 to which the station MBS1 is initially attached. Means of sending allow to send to this station 7 a message including the two addresses of the MBS1 station. The CSAT station can thus update its own CSAT table.

A Mobile IP Proxy protocol can also be implemented to manage group changes of base stations. Station 7 plays the role of HA and station T plays the role of FA.

The use of the OLSR protocol and the Mobile IP Proxy protocol is an effective solution in wireless IP networks, such as 802.16 mesh networks, for routing and mobility management, requiring relatively little change in the existing devices of the networks. wireless IP networks.

The network of FIG. 1 is such that the addressing is hierarchical. When a new device, whether MBS or mobile device, is added to the network, an initial IP address is assigned to that device. For this purpose, it is identified to which other device the new device is initially attached. For example, if the new device is a mobile device, the nearest base station is searched for, and communication is established between the new equipment and that base station, so as to agree to an attachment to the network of the base station. equipment via the base station. If the new device is a base station, the same will be done with the nearest core base station.

Then the initial IP address of the new device is defined from the IP address of the device of the network to which the new device was attached, so that the IP address of this device is determinable from the initial IP address. of the new device. It can be expected that the attachment point to which the new device has been attached determines and assigns this initial IP address. For example, CBSs determine and assign the initial IP addresses of MBSs, and MBSs determine and assign initial IP addresses of mobile devices. The central server determines and assigns the initial IP addresses of the CBSs.

Claims

A mobility management method in a group-structured wireless IP network, the network comprising, for at least one group, a plurality of base stations connected to each other in mesh mode and initially attached to said group, mobile equipment , each mobile equipment being initially connected to a parent base station among the group's base stations, in which at least one of the base stations and the mobile equipment is assigned an initial IP address comprising at least one identifier of the group to which said device is initially attached and, if appropriate, an identifier of the parent base station to which said device is initially attached, the method comprising the steps of: in case of a change of attachment of said device to the mother base station and / or to the group, assigning (32, 35) a temporary IP address to said device, said temporary IP address re including at least one identifier of the group to which said device is now attached and, if appropriate, an identifier of the parent base station to which said device is now attached, mapping (36, 37) the IP address initial with the temporary IP address, especially for forwarding messages to the device. The mobility management method according to claim 1, wherein the mapping step comprises: analyzing (31, 34) the initial IP address in order to seek to determine the group to which said device is initially attached and the case the parent base station to which said device is initially attached, and a sending (33, 37) to a wireless network installation of a message comprising the initial IP address and the temporary IP address, said installation being chosen according to a result of the analysis. 3. Mobility management method according to claim 2, wherein in case of non-determination of the group to which the device is initially attached and where appropriate the mother base station to which said device is initially attached, the message is sent. to a central server managing a set of groups (33), and in case of determination, the message is sent to the parent base station to which said device is initially attached if necessary or to a heart base station of the group to which the device is initially attached (37). 4. Mobility management method according to one of claims 1 to 3, further comprising the steps of dynamic update of a routing table (OLSR) storing the topology of the mesh network formed by the stations of the group, and using the contents of the routing table for communications within said mesh network. A computer program for storage in a memory of a device for a group-structured wireless IP network, the network comprising for at least one group a plurality of base stations connected to each other in mesh mode and initially attached to said group, mobile equipment, each mobile equipment being initially attached to a parent base station among the group's base stations, wherein at least one of the base stations and the mobile equipment is assigned an address Initial IP with at least one identifier of the group to which said device is initially attached and, where appropriate, an identifier of the parent base station to which said device is initially attached, and / or stored on a storage medium intended to cooperate with a reader of said device and / or downloaded via a network the program comprising instructions for performing the steps of, in case of a change of attachment of said device to the parent base station and / or the group, assigning a temporary IP address to said device, said temporary IP address including at least one identifier of the group to which said device is now attached and, if appropriate, an identifier of the mother base station to which said device is now attached, to match the initial IP address with the temporary IP address, in particular for forward messages to the device. A group-structured wireless IP network (4, 5), the wireless IP network comprising, for at least one group, a plurality of base stations (CBS1, MBS1, 8) connected to each other in mesh mode and initially connected to said group, mobile equipment (2, 3, AP0501, AP0301), each mobile equipment being initially attached to a parent base station among the base stations of the group, characterized in that at least one device (MBS1, AP ₀₃ 01, 2, 3, AP0501) among the base stations and the mobile equipment is assigned an initial IP address (& 1) comprising at least one identifier of the group to which said device is initially attached and, if appropriate, a user identifier. the parent base station to which said device is initially attached, in case of a change of attachment of said device to the parent base station and / or to the group, a temporary IP address (& 2) is assigned to said device, said temporary IP address including at least one identifier of the group to which said device is now attached and, where appropriate, an identifier of the mother base station to which said device is now attached, the network comprises means for matching the initial IP address and the Temporary IP address especially for transferring messages to the device. A base station (21) for a group-structured wireless IP network, the station being arranged to be attached to a group, for attaching to said station mobile equipment (2, 3), and for being connected in a wireless mode. meshed to a plurality of other base stations (MBS1, CBS1) also attached to said group, the base station including means (22) for assigning IP addresses arranged to assign to the mobile equipment attached to said base station a IP address comprising an identifier of said station and an identifier of the group to which said station is attached. The base station (21) according to claim 7, further comprising receiving means (23) for receiving a message from a mobile equipment initially attached to another base station and having an initial IP address including an identifier of said other station and an identifier of the group to which said other station is attached, processing means (22) for analyzing the initial IP address in order to seek to determine the group and the base station to which said mobile equipment is initially attached, and sending means (24) for sending to an installation of the wireless IP network the initial IP address and a temporary IP address assigned to said mobile equipment by said station, said installation being chosen by the processing means according to a result of the analysis. Base station according to one of claims 7 to 8, further comprising a routing table (OLSR) for storing the topology of the mesh network formed by the base stations (MBS1, CBS1, 21) of the group, update means for dynamically updating said routing table, and in which the station is arranged to communicate with the other base stations of the mesh network using the content of the routing table A central server (20) for a group-structured wireless IP network, the network comprising for at least one group a plurality of base stations connected together in mesh mode and attached to said group, and mobile equipment, each mobile equipment initially being attached to a parent base station among the base stations of the group, the central server comprising means (43) for receiving a first message comprising an initial IP address and a temporary IP address of the same device among the base stations and mobile network equipment, the initial IP address comprising at least one identifier of the group to which said device is initially connected and, if appropriate, an identifier of the mother base station to which said device is initially connected, the address Temporary IP comprising at least one identifier of the group to which said device is now connected and, if appropriate, an identifier of the base device to which said device is now pieced together, processing means (42) for determining from the initial IP address the group to which the device is initially attached and, if appropriate, the parent base station to which the device is initially attached, sending means (44) for sending to a core station of the group determined by the processing means and / or where appropriate to the mother station determined by the processing means a second message comprising the address Initial IP and temporary IP address