METHOD FOR ANNOUNCING THE PRESENCE OF MOBILE TELEPHONE EQUIPMENT

Abstract

In a mobile telephony service implemented by a communication system comprising satellite equipment connected to ground equipment by a satellite communication link, the satellite equipment includes a distributed unit mobile telephony device connected to a first router, and the ground equipment includes a centralized unit mobile telephony device connected to a second router. Network layer or link layer advertisement messages with a specific type-length-value format are used to advertise the presence of the distributed unit mobile telephony device and the centralized unit mobile telephony device. This conserves resources, particularly on the satellite side, to form a base station with the distributed unit mobile telephony device and the centralized unit mobile telephony device. Figure to be published with the abbreviation: Fig.2A.

Description

Title of the invention: METHOD FOR ANNOUNCING THE PRESENCE OF MOBILE TELEPHONY EQUIPMENT Technical field

[0001] The present invention relates to announcements of the presence of equipment in a mobile telephone network deployed using at least one satellite. STATE OF PRIOR ART

[0002] Satellites are increasingly being considered for deploying communication solutions, and more particularly in the context of 5th generation (5G) mobile telephony and beyond.

[0003] In a space constellation with onboard 5G equipment, Distributed Unit (DU) type equipment is carried on satellites, and Centralized Unit (CU) type equipment is positioned at various locations on the ground. As a reminder, in 5G technology, a base station can be decomposed into a CU type device and one or more DU type devices. The CU type equipment implements the higher protocol layers, such as the layers relating to the Service Data Adaptation Protocol (SDAP), the Packet Data Convergence Protocol (PDCP), and the Radio Resource Control (RRC).And each DU-type device implements, in a complementary manner, the lower protocol layers, such as the radio link control (RLC), medium access control (MAC) and physical layers.

[0004] Enabling efficient data routing between these different entities remains a delicate subject. Indeed, routing must be able to support traffic engineering and also manage potential failures of satellite links and / or nodes (satellites), in order to reroute traffic to its destination with a limited, or even zero, impact on user experience.

[0005] In current Internet service provider networks, segment routing as a data plan dominates for its flexibility, particularly by relying on the MPLS (Multiprotocol Label Switching) standard.

[0006] However, this segment-based routing involves the use of different network protocol stacks, notably the BGP (Border Gateway Protocol) in parallel with IGP (Interior Gateway Protocol). A Note that, as the BGP protocol runs on the TCP transport protocol (“Transmission Control Protocol” in English, layer 4 of the OSI model (“Open Systems Interconnection” in English)), the BGP protocol is considered to belong to the application layer (layer 7) of the OSI model.

[0007] However, in a space constellation where onboard computing resources are particularly limited, the use of these different protocol stacks is sufficient to saturate said onboard computing resources.

[0008] It is therefore desirable to overcome this drawback of the prior art. In particular, it is desirable to provide a solution that allows for the efficient use of computing resources embedded in satellites within the framework of segment routing in a mobile telephone network deployed using said satellites. Description of the invention

[0009] To this end, an announcement method is proposed herein within the framework of a mobile telephony service implemented by a communication system comprising satellite equipment connected to ground equipment by a satellite communication link, the satellite equipment including a first router and a mobile telephony device of the distributed unit type attached to the first router, the ground equipment including a second router and a mobile telephony device of the centralized unit type attached to the second router. The method is such that the first router announces the presence of the mobile telephony device of the distributed unit type and the second router announces the presence of the mobile telephony device of the centralized unit type using network layer or link layer announcement messages having a "type-length-value" (TLV) format which includes: a "type" field dedicated to announcing the presence of mobile telephony equipment;a field providing an identifier for the mobile telephony service; information indicating whether the message in question concerns a distributed unit type mobile telephony equipment presence advertisement or a centralized unit type mobile telephony equipment presence advertisement; a field providing a network layer address of the router transmitting the advertisement message in question; and a field providing a network layer address and / or a link layer address of the mobile telephony equipment whose presence is advertised by the advertisement message.

[0010] Thus, by placing these announcement messages at level 2 (link layer) of the OSI model or at level 3 (network layer) of the OSI model, the routing of packets or segments in the mobile telephone network can be easily configured without having to have substantial computing resources, which is particularly advantageous on the satellite side.

[0011] According to a particular embodiment, the announcement message announcing the presence of the distributed unit type mobile telephony equipment is transmitted by the first router when the first router detects the presence of the distributed unit type mobile telephony equipment through a local network interface device of the first router to which the distributed unit type mobile telephony equipment is connected to the first router, and the announcement message announcing the presence of the centralized unit type mobile telephony equipment is transmitted by the second router when the second router detects the presence of the centralized unit type mobile telephony equipment through a local network interface device of the second router to which the centralized unit type mobile telephony equipment is connected to the second router.

[0012] According to a particular embodiment, each advertisement message includes a label, intended to perform routing between routers by label switching and which is assigned by the router transmitting said advertisement message.

[0013] According to a particular embodiment, the first router implements a first service table and the second router implements a second service table, based on a detection of the presence of the mobile telephony equipment of the distributed or centralized unit type which are respectively attached to them and based on advertisement messages received in said "type-length-value" TLV format, each said service table being used to determine which router to contact in order to transmit data to such or such advertised mobile telephony equipment.

[0014] According to a particular embodiment, the first router performs a filtering that rejects any announcement message that announces the presence of a mobile telephony equipment of the distributed unit type.

[0015] Also proposed here is a communication system intended for use in a mobile telephony service, the communication system comprising satellite equipment connected to ground equipment by a satellite communication link, the satellite equipment including a first router and mobile telephony equipment of the distributed unit type attached to the first router, the ground equipment including a second router and mobile telephony equipment of the centralized unit type attached to the second router.The system is such that the first router is configured to advertise the presence of distributed unit type mobile telephony equipment and the second router is configured to advertise the presence of centralized unit type mobile telephony equipment using network layer or link layer advertisement messages having a type-length-value (TLV) format which includes: a type field dedicated to advertising the presence of mobile telephony equipment; a field providing an identifier for the mobile telephony service; and information indicating whether the message in question concerns a . announcement of the presence of distributed unit-type mobile telephony equipment, or if the message in question concerns a centralized unit-type mobile telephony equipment presence announcement; a field providing a network layer address of the router transmitting the announcement message in question; and

[0016] - a field providing a network layer address and / or a layer address mobile phone equipment connection whose presence is announced by the announcement message. Brief description of the drawings

[0017] The features of the invention mentioned above, as well as others, will become clearer upon reading the following description of at least one exemplary embodiment, said description being made in relation to the accompanying drawings, among which:

[0018] [Fig-1] schematically illustrates a satellite communication system used for the deployment of a mobile phone network;

[0019] [Fig.2A] schematically illustrates a message format adapted to announce the presence of a DU or CU type mobile telephony equipment, according to a first embodiment;

[0020] [Fig.2B] schematically illustrates a message format adapted to announce the presence of a DU or CU type mobile telephony equipment, according to a second embodiment;

[0021] [Fig.3] schematically illustrates a flag field format, applicable to messages from Figs. 2A and 2B;

[0022] [Fig.4A] schematically illustrates a first service table implemented by a router on the satellite side in the satellite communication system;

[0023] [Fig.4B] schematically illustrates a second service table implemented by a ground-side router in the satellite communication system;

[0024] [Fig.5A] schematically illustrates an algorithm for announcing the presence of DU type equipment by the satellite-side router in the satellite communication system;

[0025] [Fig.5B] schematically illustrates an algorithm for announcing the presence of CU type equipment made by the ground-side router in the satellite communication system;

[0026] [Fig.5C] schematically illustrates an algorithm for updating a service table upon receipt of an announcement of the presence of DU or CU type equipment by a router connected to a DU type mobile telephony equipment;

[0027] [Fig. 5D] schematically illustrates a service table update algorithm upon receipt of a DU or CU type equipment presence announcement by a router connected to a CU type mobile telephony device; and

[0028] [Fig.6] schematically illustrates a hardware platform usable for implement satellite communication system equipment.

[0029] DETAILED DESCRIPTION OF IMPROVEMENTS

[0030] Fig. 1 schematically illustrates a satellite communication system 100 used for the deployment of a mobile telephone network.

[0031] A satellite includes an SE 101 satellite equipment. The SE 101 satellite equipment includes a router, referred to herein as the SR 121 satellite router.

[0032] On the ground, a ground equipment GE 102 is in communication with the satellite equipment SE 101 via a satellite communication link SCL 150. The ground equipment GE 102 includes a router, referred to here as ground router GR 122.

[0033] The SR 121 satellite router includes a satellite communication interface device 131 adapted and configured to communicate via the SCL satellite communication link 150. The SR 121 satellite router further includes a LAN (“Local Area Network”) type communication interface device 141 adapted and configured to communicate, via a communication link 151, with a DU (“Distributed Unit”) type mobile telephony equipment 111.

[0034] The SR 121 satellite router is configured to be connected to a DU-type mobile telephony device (DU 111 device), and is therefore a router embedded in a satellite. In a particular embodiment, the SR 121 satellite router has received a command, for example called "service-node-sid-du", indicating: (1) that a DU-type mobile telephony device is intended to be connected to it, (2) that this DU-type mobile telephony device has such and such an identifier (a serial number and / or a MAC address), and (3) that this DU-type mobile telephony device will be used in a mobile telephony service having such and such an identifier (hereafter referred to as the SNSID).

[0035] The GR 122 ground router includes a satellite communication interface device 132 adapted and configured to communicate via the SCL satellite communication link 150. The GR 122 ground router further includes a LAN-type communication interface device 142 adapted and configured to communicate, via a communication link 152, with a CU-type mobile telephony equipment (“Centralized Unit”) 112. The GR 122 ground router further includes an inter-router interface device 162 adapted and configured to communicate with at least one other OR router 123 within a communication network supporting data packet routing for the mobile telephony network.

[0036] The GR 122 ground router is configured to be connected to a CU-type mobile phone device (CU 112 device) and is therefore a ground router. In a particular embodiment, the GR 122 ground router has received a command, for example called "service-node-sid-cu", indicating: (1) that a CU-type mobile phone device is intended to be connected to it, (2) that this CU-type mobile phone device has such and such an identifier, and (3) that this CU-type mobile phone device will be used in a mobile phone service having such and such an identifier (hereafter referred to as the SNSID).

[0037] Figure 1 therefore shows another OR 123 router, which itself can be connected to one or more additional routers in the communication network supporting data packet routing for the mobile telephone network. The OR 123 router thus includes an inter-router interface device 163 adapted and configured to communicate with the ground router GR 122 and with the additional router(s) (not shown).

[0038] The inter-router interface devices 162, 163 can support several logical interfaces on the same physical interface to create communication links with several routers of the communication network supporting the routing of data packets for the mobile telephony network.

[0039] In a particular embodiment, the ground router OR 123 includes a satellite communication interface device 133 adapted and configured to establish an alternative satellite communication link SCLb 153 with the satellite equipment SE 101. The alternative satellite communication link SCLb 153 allows the satellite communication link SCL 150 to be supplemented in the event of a failure of the latter (e.g., the occurrence of adverse weather conditions in the vicinity of the ground equipment GE 102). Packet routing between the equipment CU 112 and the equipment DU 111 can thus be maintained via the OR 123 router.

[0040] Together, the CU 112 equipment and the DU 111 equipment form a base station of a mobile telephone network.

[0041] In order to jointly form the base station of a mobile telephone network, the CU 112 and DU 111 equipment must be advertised so that data routing between the CU 112 and DU 111 equipment can take place and adapt to changes in communication conditions. To do this, their respective routers SR 121 and GR 122 generate and transmit advertisement messages in a specific format of a Layer 2 (Link Layer) or Layer 3 (Network Layer) protocol of the OSI model. Thus, these advertisement messages have a "Type-Length-Value" (TLV) format of this Layer 2 (Link Layer) or Layer 3 (Network Layer) protocol of the OSI model, dedicated to advertising the presence of mobile telephone equipment.

[0042] Preferably, the SR 121 and GR 122 routers generate and send these advertisement messages in a specific format of a layer 3 (network layer) protocol of the OSI model.

[0043] Thus, by placing these announcement messages at layer 2 (data link layer) or layer 3 (network layer) of the OSI model, the routing of packets or segments in the mobile telephone network, between the CU 112 and DU 111 equipment, can be easily configured without requiring significant computing resources, which is particularly advantageous on the satellite side. This advantage could not be achieved with announcements made via a protocol such as BGP, due to the processing of the various headers required by the use of a layer 7 (application layer) protocol of the OSI model.

[0044] Fig. 2A schematically illustrates a type-length-value format TLV, adapted to announce the presence of a DU or CU type mobile telephony equipment, according to a first embodiment.

[0045] The message format schematically illustrated in [Fig. 2A] comprises:

[0046] - a field T providing message type information (for example, on 8 bits);

[0047] - a field L providing message length information (for example, on 8 bits);

[0048] - a field F providing a set of flags (for example, on 8 bits);

[0049] - a possible P field of padding data in order to perform an alignment of the T, L, F and P fields on a predefined number of bits (for example, on 32 bits);

[0050] - an SNSID field (Service Node Segment Identifier) ​​providing a service identifier;

[0051] - an LBA (LoopBack Address) field, providing an address of loopback, which identifies the router that transmitted the message in question; and

[0052] - an IPA / EA field (“Internet Protocol Address” / “Ethernet Address”, in English) providing a level 3 (network layer) address of the OSI model (e.g., an IP address), or respectively level 2 (link layer) of the OSI model of DU or CU type advertised mobile telephony equipment (e.g., a 32-bit IPv4 address or a 128-bit IPv6 address).

[0053] To announce the presence of DU or CU type mobile telephony equipment, the T field takes a dedicated value. For example, the T field takes a value specifically allocated by the IANA (Internet Assigned Numbers Authority) for the announcement, at layer 3 of the OSI model, of the presence of DU or CU type mobile telephony equipment.

[0054] Field F includes information indicating whether the message relates to an announcement of the presence of a DU type mobile telephony equipment or whether the message relates to an announcement of the presence of a CU type mobile telephony equipment.

[0055] The F field potentially includes other information. In a particular embodiment, as schematically illustrated in [Fig. 3], the F field includes (1 bit per flag):

[0056] - a Fl flag, which indicates the presence of a field of type SNSID;

[0057] - an F2 flag, which indicates, in the case of a layer 3 (network layer) protocol of the OSI model, whether the address provided in the IPA field of [Fig.2A] is an IPv4 address or an IPv6 address. For example, the F2 flag takes the value "0" if the address provided in the IPA field is an IPv4 address and the F2 flag takes the value "1" if the IP address provided in the IPA field is an IPv6 address;

[0058] - an F3 flag, used in the case of the message format of [Fig.2B], which indicates if the OSI model layer 3 (network layer) address provided in an IPA field is supplemented by an OSI model layer 2 (link layer) address in an additional EA field. For example, the F3 flag takes the value "0" when the EA field is absent, and the F3 flag takes the value "1" when the EA field is present and contains the OSI model layer 2 (link layer) address (e.g., MAC address) in question (see [Fig.2B]);

[0059] - an F4 flag, which is said information indicating whether the message concerns a announcement of the presence of a DU type mobile telephone equipment or if the message concerns an announcement of the presence of a CU type mobile telephone equipment. For example, the F4 flag takes the value "0" when the message concerns an announcement of the presence of a CU type mobile telephone equipment, and the F4 flag takes the value "1" when the message concerns an announcement of the presence of a DU type mobile telephone equipment.

[0060] Returning to [Fig. 2A], the SNSID field is intended to indicate an SNSID identifier, which identifies the service for which the advertisement is being made. SNSID identifiers are pre-established, and each mobile network operator typically uses distinct SNSID identifiers specific to them. Several mobile telephony services, operated by different mobile network operators, can thus coexist in a satellite constellation. Therefore, for each base station, the CU-type mobile telephony equipment and the DU-type mobile telephony equipment that make up said base station use the same SNSID identifier value. Note that other SNSID identifier values ​​could also be assigned to services other than mobile telephony services, such as satellite maintenance services.

[0061] The loopback address, provided in the LBA field, helps prevent broadcast loops. A router that receives an advertisement message for a DU or CU type mobile phone device to which it is itself connected must ignore the advertisement message. Furthermore, the loopback address, provided in the LBA field, is used by each other router to determine which router the DU or CU type mobile phone device is connected to, and to use its routing table to determine how to propagate packets addressed to that DU or CU type mobile phone device.

[0062] The OSI model's Layer 3 (Network Layer) or Layer 2 (Link Layer) address in the IPA / EA field identifies the CU or DU type mobile telephony equipment targeted by the advertisement. This depends on which type of address is used to address CU or DU type mobile telephony equipment in the mobile telephony network.

[0063] Figure 2B schematically illustrates a message format that is a variant of Figure 2A. The message format in Figure 2B is more complete. One or more fields shown in Figure 2B that are not in Figure 2A can be added to provide more information to a router receiving the corresponding advertisement, and thus allow for the implementation of more features.

[0064] In particular, [Fig.2B] shows a particular embodiment where the message format shown further includes an ID field providing an identifier, for example on 32 bits, of the mobile telephony equipment of type DU or CU concerned.

[0065] In addition, on [Fig.2B], a level 3 (network layer) address of the OSI model is included in the IPA field and a level 2 (link layer) address of the OSI model is included in the EA field.

[0066] Fig. 2B also shows a particular embodiment where the message format presented further includes an MPLSL (MPLS Label) field, providing a label. A label is a packet flow identifier for a given service (identified by the SNSD identifier) ​​originating from a DU or CU type mobile telephony device associated with that service. The label is generated randomly or pseudo-randomly by the router to which the DU or CU type mobile telephony device in question is attached. This is a well-known mechanism for performing inter-router routing by label switching, enabling segment-based routing that facilitates dynamic route changes between routers without interruption of routing service (for example, when ground-to-satellite communication switches from the SCL 150 satellite communication link to the alternative SCLb 153 satellite communication link).

[0067] It follows from the above that the message format presented in relation to [Fig. 2A] or 2B is applicable to layer 3 (network layer) protocols of the model OSI as well as Layer 2 (data link layer) protocols of the OSI model. The message format shown in [Fig. 2A] or 2B is thus compatible with the OSPF (Open Shortest Path First) routing protocol, which is a Layer 3 (network layer) protocol of the OSI model. The message format shown in [Fig. 2A] or 2B is also compatible with the IS-IS (Intermediate System to Intermediate System) routing protocol, which is a Layer 2 (data link layer) protocol of the OSI model.

[0068] Thus, thanks to the message format presented in relation to [Fig. 2A] or 2B, a DU or CU type mobile telephony device can be efficiently advertised without resorting to a protocol stack extending up to layer 7 (application layer) of the OSI model, as with the aforementioned BGP protocol. The computing resources required to process the advertisements needed to match the DU 111 device with the CU 112 device are therefore reduced.

[0069] The announcement messages, according to the format described above, are propagated between the routers, and the information they contain is listed in service tables which complement routing tables already classically present in the routers, specifically for the connection of DU and CU type mobile telephony equipment.

[0070] Fig. 4A schematically illustrates a first service table implemented by the SR 121 router. The service table is updated by discovery or confirmation of the presence of DU or CU type mobile telephony equipment, for a pre-configured service (identified by its SNSID identifier).

[0071] In a particular embodiment, the DU 111 device announces its presence to the SR 121 router by sending an "ARP Gratuitous" message (where ARP stands for "Address Resolution Protocol"). An "ARP Gratuitous" message is an ARP-compliant message that was not triggered by a previous request. The "ARP Gratuitous" message is sent by broadcast from a communication network node, so that this communication network node spontaneously announces its IP address-MAC address mapping to the entire communication network. The DU 111 device can do this at regular intervals. The SR 121 router can then use the "ARP Gratuitous" messages transmitted by the DU 111 device, and received by the SR 121 router via broadcast, to populate the first service table.The SR 121 router typically stores the information contained in messages transmitted via the ARP protocol in a dedicated table, called the "ARP table". For example, the SR 121 router learned the MAC address of the DU 111 device using the "service-node-sid-du" command mentioned earlier.

[0072] It should be noted that the use of the ARP protocol relies on IPv4 type IP addresses. Identical operation would, however, be obtained with IPv6 type IP addresses and the use of the NDP protocol (Neighbor Discovery Protocol).

[0073] The SR 121 router will also use the content of CU or DU type mobile telephony equipment announcement messages received by the SR 121 router for the same service for which the SR 121 router was configured (e.g., by the "service-node-sid-du" command).

[0074] Preferably, as described below in relation to [Fig.5C], the SR 121 router does not take into account DU type mobile telephony equipment announcement messages that would be received by the SR 121 router from other routers.

[0075] Each line of the first service table corresponds to a description of a DU or CU type mobile telephony equipment whose presence has been listed by the SR 121 router. Each line includes the information contained in the "type-length-value" format (see Figs. 2A and 2B) of an announcement message, either as received or as transmitted.

[0076] Thus, in a particular embodiment, the first service table comprises the following columns:

[0077] - a column, labeled SNSID on [Fig.4A], which identifies the service for which the SR 121 router has been configured (as already mentioned, the SR 121 router may also have to manage several services in parallel (mobile telephony, satellite maintenance...));

[0078] - a column, labeled DU / CU on [Fig.4A], which indicates whether the line in question of the service table describes said mobile telephony equipment of type DU or said mobile telephony equipment of type CU;

[0079] - a column, labeled Id on [Fig.4A], which optionally provides an identifier of the type serial number of the mobile phone equipment of type DU or CU in question;

[0080] - a column, labeled LBA on [Fig.4A], which provides a level 3 address of the OSI model (typically an IP address) of the router associated with the DU or CU type mobile telephony equipment in question ("loopback address");

[0081] - a column, labeled MPLSL on [Fig.4A], which optionally provides a label value that has been assigned for the packet stream emitted by the DU or CU type mobile telephony equipment in question;

[0082] and furthermore, one and / or the other of the following columns:

[0083] - a column, labeled IPA on [Fig.4A], which provides a level 3 address of the OSI model (typically an IP address) of the DU or CU type mobile telephony equipment in question; and

[0084] - a column, labeled EA on [Fig.4A], which provides an Ethernet address (MAC, therefore level 2 of the OSI model) of the mobile telephony equipment of type DU or CU in question.

[0085] As shown in [Fig.4A], several CU type mobile telephony devices can be associated with the same service (same SNSID identifier), typically when these CU type mobile telephony devices belong to the same mobile telephony operator.

[0086] Thus, illustratively in [Fig. 4A], for a mobile telephony service identified by SNSID0 (assigned to router SR 121 by configuration), the first service table describes a single DU-type mobile telephony device (identified by DUO), with a Layer 3 (Network Layer) address IP_DU0 and a Layer 2 (Link Layer) address MAC_DU0, to which is also associated a label value MPLSL1. The corresponding row of the first service table also includes the Layer 3 (Network Layer, typically the IP address) address of the router to which the DU-type mobile telephony device in question is connected.

[0087] Within the framework of [Fig. 1], this mobile telephony equipment which is identified by DUO on [Fig.4A] is the equipment DU 111, and the address IP_LB_DU0 is the level 3 (network layer) address of the router SR 121.

[0088] Next, the example of the first service table in [Fig. 4A] lists, for the service identified by SNSID0, four CU-type mobile telephony devices (identified by CU0 to CU3), with their respective Layer 3 (Network Layer) addresses IP_CU0 to IP_CU3 and their respective Layer 2 (Link Layer) addresses MAC_DU0 to MAC_DU3, to which are also associated MPLSL2 to MPLSL5 label values. In addition, for each of these CU-type mobile telephony devices, the first service table also indicates the Layer 3 (Network Layer, typically the IP address) address of the router to which the CU-type mobile telephony device in question is connected (IP_LB_CU0 to IP_LB_CU3 addresses).

[0089] In the context of [Fig. 1], for example, the mobile telephony equipment identified by CU0 in [Fig. 4A] is the CU 112 equipment, and the IP_LB_CU0 address is the level 3 (network layer) address of the GR 122 router.

[0090] Thus, the first service table, which is implemented by the satellite-side router SR 121, identifies the DU-type mobile telephony equipment that is onboard the satellite (DU 111 equipment), as well as each CU-type mobile telephony device that has been advertised to the satellite-side router SR 121 and with which DU type mobile telephony equipment is capable of being interconnected via the SCL 150 satellite communication link (including CU 112 equipment).

[0091] The first service table is thus constructed by the SR 121 router, based on its detection of the presence of the DU 111 equipment (DUO in the first service table of [Fig.4A]) and the announcements received from other routers.

[0092] The first service table in [Fig. 4A] does not contain a description of any other DU-type mobile telephony equipment besides that connected to the SR 121 router because, in a particular embodiment, the SR 121 router performs filtering that rejects DU-type telephony network equipment presence announcement messages from other routers. Direct communication between DU-type telephony network equipment is not useful in such a mobile telephony network, and this filtering improves memory consumption on the satellite side.

[0093] A second service table, schematically illustrated by [Fig.4B], is implemented by the GR 122 router. The service table is updated by discovery or confirmation of the presence of DU or CU type mobile telephony equipment, for a pre-configured service (identified by its SNSID identifier).

[0094] In a particular embodiment, the CU 112 device announces its presence by sending an "ARP Gratuitous" message. The CU 112 device can do this at regular intervals. The GR 122 router can then use the "ARP Gratuitous" messages transmitted by the CU 112 device, and received by the GR 122 router via broadcast transmission, to enrich the second service table. The GR 122 router typically stores the information contained in the messages transmitted according to the ARP protocol in the ARP table. For example, the GR 122 router learned the MAC address of the CU 112 device using the "service-node-sid-cu" command mentioned earlier.

[0095] Figure 4B shows an example consistent with that of Figure 4A. Thus, the second service table has the same columns as the first service table.

[0096] In addition to the entries in the first service table of [Fig. 4A], the second service table of [Fig. 4B] includes entries for other DU-type telephony network equipment that has also been advertised for the same service, identified by the identifier SNSID0, and which is typically located on other satellites in the constellation. As such, the second service table of [Fig. 4B] describes another DU-type telephony network equipment, identified by the identifier DU1, with a Layer 3 (Network Layer, typically IP address) address IP_DU1 and a Layer 2 (Link Layer) address MAC_DU1, to which is also associated an MPLSL6 label value. The line The corresponding entry in the second service table also includes the Layer 3 (Network Layer, typically the IP address) address of the router to which the DU-type mobile phone equipment in question is connected (IP_LP_DU1). The second service table in [Fig. 4B] describes yet another DU-type telephony network device, identified by the identifier DU2, with a Layer 3 (Network Layer, typically the IP address) IP_DU2 and a Layer 2 (Link Layer) MAC_DU2 address, which is also associated with an MPLSL7 label value. The corresponding entry in the second service table also includes the Layer 3 (Network Layer, typically the IP address) address of the router to which the DU-type mobile phone equipment in question is connected (IP_LP_DU2).

[0097] As explained below, service tables are used by routers to perform data routing, as described below with Figs. 5C and 5D.

[0098] Figure 5A schematically illustrates an algorithm for announcing the presence of a DU-type mobile telephony device by the router to which it is connected. Figure 5A is described in more detail below in the context of the presence announcement of the DU 111 device by the SR 121 router.

[0099] In a step 502, the SR 121 router detects the presence (e.g., activation) of the DU 111 equipment connected through its LAN-type communication interface device 141.

[0100] For example, the SR 121 router detects the presence (e.g., activation) of the DU 111 device by finding a match for the DU 111 device in the ARP table after the DU 111 device sends an "ARP Gratuitous" message. The SR 121 router then retrieves Layer 3 address information (e.g., IP address) for the DU 111 device from the ARP table that corresponds to its Layer 2 (MAC) address, which is known to the SR 121 router through prior configuration. Alternatively, the SR 121 router detects the presence (e.g., activation) of the DU 111 device after receiving a message from the DU 111 device in which the DU 111 device identifies itself.

[0101] In step 504, the SR 121 router accordingly enriches the first service table by filling in the columns for the corresponding entry, as shown above in relation to [Fig. 4A] for the equipment identified by the DUO identifier. The SR 121 router thus completes the first service table for this entry dedicated to the DU 111 equipment with the SNSID service identifier known from prior configuration and an MPLSL label value. The SR 121 router assigns this MPLSL label value, preferably randomly or pseudo-randomly.

[0102] In step 506, router SR 121 generates and transmits an advertisement message announcing the presence of equipment DU 111 for the service identified by the SNSID. The advertisement message has the format as previously described, including in particular the type value (T field) that corresponds to this type of message (advertisement), the SNSID identifier (SNSID field), an indication that the advertisement concerns a DU type mobile telephony equipment (F4 flag), the layer 3 (network layer) address of the SR 121 router (loopback address), and the assigned label value (MPLSL field) as well as at least one address of the DU 111 equipment (IA and / or EA fields).

[0103] The transmission of this message announcing the presence of the DU 111 equipment will allow other routers, including the GR 122 router, to update their respective service tables (as illustrated in [Fig.4B]) with respect to the DU 111 equipment, as described below in relation to [Fig.5C].

[0104] Figure 5B schematically illustrates an algorithm for announcing the presence of a CU-type mobile phone device by the router to which it is connected. Figure 5B is described in more detail below in the context of the presence announcement of the CU 112 device by the GR 122 router.

[0105] In a step 522, the GR 122 router detects the presence (e.g., activation) of the CU 112 equipment connected through its LAN-type communication interface device 142.

[0106] For example, router GR 122 detects the presence (e.g., activation) of device CU 112 by finding a match for device CU 112 in the ARP table after CU 112 sends an "ARP Gratuitous" message. Router GR 122 then retrieves Layer 3 address information (e.g., IP address) for device CU 112 from the ARP table that matches its Layer 2 (MAC) address, which is known to router GR 122 through prior configuration. Alternatively, router GR 122 detects the presence (e.g., activation) of device CU 112 after receiving a message from device CU 112 in which device DU 112 identifies itself.

[0107] In step 524, the GR 122 router accordingly enriches the second service table by filling in the columns for the corresponding entry, as shown above in relation to [Fig. 4B] for the equipment identified by the identifier CU0. The GR 122 router thus completes the second service table for this entry dedicated to the CU 112 equipment with the SNSID service identifier known from prior configuration and an MPLSL label value. The GR 122 router assigns this MPLSL label value, preferably randomly or pseudo-randomly.

[0108] In step 526, router GR 122 generates and transmits an advertisement message announcing the presence of equipment CU 112 for the service identified by the SNSID. The advertisement message has the format as previously described, including in particular the type value (T field) which corresponds to this type of message (advertisement), the SNSID (SNSID field), an indication that the advertisement concerns equipment of CU type mobile telephony (F4 flag), the GR 122 router's level 3 (network layer) address (loopback address), and the assigned label value (MPLSL field) as well as at least one CU 112 equipment address (IA and / or EA field).

[0109] The transmission of this message announcing the presence of the CU 112 equipment will allow other routers, including the SR 121 router, to update their respective service tables (as illustrated in Figs. 4A and 4B) with respect to the CU 112 equipment, as described below in relation to [Fig. 5D].

[0110] If a router does not know the type dedicated to mobile telephony equipment advertisements of type DU or CU as described above, this router does not perform any other processing upon receipt of a message of this type than to propagate said message to other routers which are connected to it.

[0111] Fig. 5C schematically illustrates a message processing algorithm for announcing the presence of CU or DU type mobile telephony equipment by a router connected to DU type mobile telephony equipment (such as the SR 121 router).

[0112] In a step 542, the router in question receives a message announcing the presence of mobile telephony equipment of type CU or DU. The announcement message is a Layer 3 (Network Layer) message of the OSI model or a Layer 2 (Link Layer) message of the OSI model (preferably, Layer 3 of the OSI model), and has the "type-length-value" format as described above.

[0113] In a step 544, the router in question preferentially operates a filtering that rejects any DU type mobile telephony equipment presence announcement message.

[0114] In a step 546, the router in question performs optional additional filtering which rejects the CU or DU type mobile telephony equipment presence announcement message.

[0115] The router rejects any CU or DU type mobile phone equipment presence announcement message that originated from the router in question (and that another router propagated to it).

[0116] The router rejects any CU or DU type mobile telephony equipment presence advertisement message for a service, identified by an SNSID identifier, that is not included in its service table.

[0117] The filtering steps 544 and 546 can be carried out in a different order than that shown above.

[0118] In a step 548, the router in question enriches its service table (first service table) as needed, that is, according to the filtering possibly carried out in steps 544 and 546. The router in question uses for this purpose the information contained in the message received in step 542.

[0119] In a step 550, the router in question uses the service table thus enriched to perform data routing.

[0120] When the router receives data concerning a service whose SNSID identifier is not listed in its service table, the router in question discards the received data.

[0121] When the router receives data from the connected DU-type mobile telephony equipment (via its LAN 141 communication interface device for the SR 121 router), the router examines the service table (first service table) to identify the address (LBA) of the router to which the CU-type mobile telephony equipment to which the data is addressed is connected (identified by its OSI model layer 3 (network layer) or OSI model layer 2 (data link layer) address, as found in the IPA or EA column, respectively, of the service table). When labels are used, the router in question adds the associated label to the service table and propagates the data to the router to which the CU-type mobile telephony equipment in question is connected by referring to its routing table.This label is removed by the router to which the CU-type mobile telephony equipment is attached before propagating (via its LAN 142 type communication interface device for the GR 122 router) to the CU-type mobile telephony equipment in question.

[0122] When the router receives data destined for the connected DU-type mobile telephony equipment, the router examines the service table (first service table). The address (LBA) of the router to which the DU-type mobile telephony equipment in question is its own, and the router forwards the data to the connected DU-type mobile telephony equipment (via its LAN 141 communication interface device for the SR 121 router). The first service table allows for checks to be performed to ensure that the received data is consistent (SNSID, MPLSL, ID, addresses).

[0123] Fig. 5D schematically illustrates an algorithm for processing a message announcing the presence of CU or DU type mobile telephony equipment by a router connected to a CU type mobile telephony equipment (such as the GR 122 router).

[0124] In a step 562, the router in question receives a message announcing the presence of mobile telephony equipment of type CU or DU. The announcement message is a Layer 3 (Network Layer) message of the OSI model or a Layer 2 (Link Layer) message of the OSI model (preferably, Layer 3 of the OSI model) and has the "type-length-value" format as described above.

[0125] In a step 544, the router in question performs an optional filtering which rejects the CU or DU type mobile telephony equipment presence announcement message.

[0126] The router rejects any CU or DU type mobile phone equipment presence announcement message that originated from the router in question (and that another router propagated to it).

[0127] The router rejects any CU or DU type mobile telephony equipment presence advertisement message for a service, identified by an SNSID identifier, that is not included in its service table.

[0128] In a step 566, the router in question enriches its service table (second service table) as needed, that is, according to the filtering possibly carried out in step 564. The router uses for this purpose the information contained in the message received in step 562.

[0129] In a step 568, the router in question uses the service table thus enriched to perform data routing.

[0130] When the router receives data concerning a service whose SNSID identifier is not listed in its service table, the router in question discards the received data.

[0131] When the router receives data from the connected CU mobile phone equipment (via its LAN 142 communication interface device for the GR 122 router), the router examines the service table (second service table) to identify the address (LBA) of the router to which the DU or CU mobile phone equipment to which the data is addressed is connected (identified by its OSI model layer 3 (network layer) or OSI model layer 2 (data link layer) address, as found in the IPA or EA column, respectively, of the service table). When labels are used, the router in question adds the associated label to the service table and propagates the data to the router to which the DU or CU mobile phone equipment in question is connected by referring to its routing table.This label is removed by the router to which the DU or CU type mobile telephony equipment is attached before propagating (via its LAN 142 type communication interface device for the GR 122 router) to the DU or CU type mobile telephony equipment in question.

[0132] When the router receives data destined for the CU-type mobile phone equipment to which it is attached, the router examines the service table (second service table). The address (LBA) of the router to which the CU-type mobile phone equipment in question is its own, and the router forwards the data to the CU-type mobile phone equipment to which it is attached. connected (via its LAN 142 type communication interface device for the SR 122 router). The second service table allows for checks that the received data is consistent (SNSID, MPLSL, ID, addresses).

[0133] Fig. 6 schematically illustrates an example of a hardware architecture that can be used to implement equipment for the satellite communication system 100. This hardware architecture can be used in particular to implement the SR 121 router, the GR 122 router, the DU 111 equipment and the CU 112 equipment.

[0134] The hardware architecture includes, connected by a communication bus 610: a processor or CPU (for "Central Processing Unit") 601, or a cluster of such processors, such as GPUs ("Graphics Processing Units"); a random access memory (RAM) 602; a read-only memory (ROM) 603, or a rewritable memory of the type EEPROM ("Electrically Erasable Programmable ROM"), for example of the Flash type; a data storage device, such as a hard disk drive (HDD) 604, or a storage media reader, such as an SD card reader (for "Secure Digital"); a set of input and / or output interfaces 605, such as communication interfaces.

[0135] The 601 processor is capable of executing instructions loaded into RAM 602 from ROM 603, external memory (not shown), storage media such as an SD card or HDD, or a communication network. When the hardware platform is powered on, the 601 processor is capable of reading instructions from RAM 602 and executing them. These instructions form a computer program causing the 601 processor to implement the steps, behaviors, and algorithms described herein.

[0136] All or part of the steps, behaviors, and algorithms described herein can thus be implemented in software form by executing a set of instructions by a programmable machine, such as a DSP (Digital Signal Processor) or a processor, or be implemented in hardware form by a dedicated machine or component (chip) or a set of dedicated components (chipset), such as an FPGA (Field-Programmable Gate Array) or an ASIC (Application-Specific Integrated Circuit). Generally, the hardware platform comprises electronic circuitry arranged and configured to implement the steps, behaviors, and algorithms described herein.

Claims

Demands

1. An advertising method within the framework of a mobile telephony service implemented by a communication system (100) comprising satellite equipment (101) connected to ground equipment (102) by a satellite communication link (150, 153), the satellite equipment (101) including a first router (121) and mobile telephony equipment of the distributed unit type (111) attached to the first router (121), the ground equipment (102) including a second router (122) and mobile telephony equipment of the centralized unit type (112) attached to the second router (122),characterized in that the first router (121) advertises (506) the presence of the distributed unit type mobile telephony equipment (111) and the second router (122) advertises (526) the presence of the centralized unit type mobile telephony equipment (112) using network layer or link layer advertisement messages having a type-length-value (TLV) format which includes: - a type field (T) dedicated to advertising the presence of mobile telephony equipment; - a field (SNSID) providing an identifier of the mobile telephony service; - information (F,F4) indicating whether the message in question concerns a distributed unit-type mobile phone equipment presence advertisement or a centralized unit-type mobile phone equipment presence advertisement; - a field (LBA) providing a network layer address of the router transmitting the advertisement message in question; and - a field (IPA / EA) providing a network layer address and / or a link layer address of the mobile phone equipment whose presence is advertised by the advertisement message.

2. A method according to claim 1, wherein the announcement message announcing the presence of the distributed unit type mobile telephony equipment is transmitted by the first router (121) when the first router (121) detects the presence of the distributed unit type mobile telephony equipment (111) through a local network interface device (141) of the first router (121) to which the distributed unit type mobile telephony equipment (111) is connected to the first router (121), and the announcement message announcing the presence of the centralized unit type mobile telephony equipment (112) is transmitted by the second router (122) when the second router (122) detects the presence of the centralized unit type mobile telephony equipment (112) through a local network interface device (142) of the second router (122) to which the centralized unit type mobile telephony equipment (112) is connected to the second router (122).

3. A method according to claim 1 or 2, wherein each advertisement message includes a label, intended to perform routing between routers by label switching and which is affected by the router transmitting said advertisement message.

4. A method according to any one of claims 1 to 3, wherein the first router (121) implements a first service table and the second router (122) implements a second service table, based on a presence detection of the mobile telephony equipment of the distributed unit type (111) or centralized unit type (112) which are respectively attached to them and on advertisement messages received in said "type-length-value" TLV format, each said service table being used to determine which router to contact in order to transmit data to any advertised mobile telephony equipment.

5. A method according to claim 4, wherein the first router (121) performs a filtering (542) which rejects any advertisement message which announces the presence of a distributed unit type mobile telephony equipment.

6. A communication system (100) intended for use in a mobile telephony service, the communication system (100) comprising satellite equipment (101) connected to ground equipment (102) by a satellite communication link (150, 153), the satellite equipment (101) including a first router (121) and distributed unit-type mobile telephony equipment (111) connected to the first router (121), the ground equipment (102) including a second router (122) and centralized unit-type mobile telephony equipment (112) connected to the second router (122), characterized in that the first router (121) is configured to advertise (506) the presence of the mobile telephony equipment of distributed unit type (111) and the second router (122) is configured to advertise (526) the presence of the centralized unit type mobile telephony equipment (112) using network layer or link layer advertisement messages having a type-length-value (TLV) format which includes: - a "type" field (T) dedicated to announcing the presence of mobile phone equipment; - a field (SNSID) providing an identifier for the mobile phone service; - information (F, F4) indicating whether the message in question concerns an announcement of the presence of mobile telephony equipment of the distributed unit type or whether the message in question concerns an announcement of the presence of mobile telephony equipment of the centralized unit type; - a field (LBA) providing a network layer address of the router transmitting the advertisement message in question; and - a field (IPA / EA) providing a network layer address and / or a link layer address of the mobile telephony equipment whose presence is advertised by the advertisement message.

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