WO2022128122A1

WO2022128122A1 - Processing a request in a mobile communication system for a service of an access node

Info

Publication number: WO2022128122A1
Application number: PCT/EP2020/087142
Authority: WO
Inventors: Philippe Godin; Bruno Landais; Laurent Thiebaut; Ömer BULAKCI; Subramanya CHANDRASHEKAR
Original assignee: Nokia Technologies Oy
Priority date: 2020-12-18
Filing date: 2020-12-18
Publication date: 2022-06-23
Also published as: EP4349120A1

Abstract

A method, apparatus and computer program is described comprising: sending a request, from a first access node of a mobile communication system, for a service offered by at least one other access node, the request comprising at least one of a URI and a discovery header identifying said at least one other node; and receiving a response to the service request originating from the said at least one other access node.

Description

PROCESSING A REQUEST IN A MOBILE COMMUNICATION SYSTEM FOR A SERVICE OF AN ACCESS NODE

Field

The present specification relates to mobile communication systems.

Background

A node of a mobile communication system may wish to obtain information about other nodes of the mobile communication system. For example, a node may wish to obtain information regarding services provided by other nodes. There remains a need for further developments in this field.

Summary

In a first aspect, this specification describes an apparatus (such as an access node of a mobile communication system), comprising means for performing: sending a request, from a first access node of a mobile communication system, for a service offered by at least one other access node, the request comprising at least one of a URI and a discovery header identifying said at least one other access node; and receiving a response to the service request originating from the said at least one other access node. Some example embodiments further comprise means for performing: sending a discovery request to a network repository function of the mobile communication system, wherein the discovery request identifies the requested service; receiving a discovery response from the network repository function in response to said discovery request, wherein the discovery response comprises a list of service identifiers or URIs; and determining, based on said discoveiy response, a URI corresponding to the service offered by the at least one other access node, wherein sending the request for said service comprises sending said URI corresponding to the service offered.

The request for the service may be sent to the at least one other access node and the response originating from the at least one other access node may be received directly from the at least one other access node. Alternatively, the request for the service may be sent from the first access node to a communication proxy including the URI corresponding to the service or a discovery header identifying the corresponding service, wherein the apparatus further comprises means for performing: receiving a response to the service request at the first access node from said at least one other access node via the communication proxy.

In some example embodiments the request for said service is sent to a communication proxy and the response to said service request is received via the communication proxy.

The communication proxy may send a discovery request to a network repository function of the mobile communication system, wherein the discovery request identifies said service, if said service request does not include a URI and the communication proxy does not already know the URI of said service.

The requested service may be one of: transport network layer discovery, handover preparation, handover cancellation, handover report, indication of handover success, retrieval of a UE context, release of a UE context, transfer of sequence number statuses, request for paging in access network, request for transport layer addresses, request for data forwarding, request for adding secondary node or secondary PScell/SCells, request for modification of UE context in secondary node, indication of reconfiguration complete, transfer of a radio resource control message, notification of activity in a node or a cell, request for counter check, report of radio access type data usage, request for trace, request for parameters configuration update, exchange of interference management parameters, change of cell mobility settings, resource status reporting, access and mobility indication, and energy saving mode request. Further possible services will be apparent to the skilled person.

Some example embodiments further comprise means for performing: sending a request identifying a transport network layer discovery service offered by the at least one other access network node; receiving a response to the transport network layer discovery request originating from the said at least one other access node which response comprises a transport network layer address; and using the received transport network address to setup a user plane or control plane interface with the at least one other access node.

Some example embodiments further comprise means for performing: sending a discovery request to a network repository function of the mobile communication system, wherein the discovery request requests for all services offered by at least one other access node; and receiving a discovery response from the network repository function in response to said discovery request, wherein the discovery response comprises a list of services offered by the other access node and information allowing the building of the corresponding URIs. The apparatus may further comprise means for performing: determining whether the list of services includes a transport network layer discovery service.

Some example embodiments further comprise means for performing: sending a request, from a first access node of a mobile communication system, for a service offered by at least one other access node, wherein the service is a transport network layer discovery service, in the event that the list of services is determined to include said transport network discovery service, and comprising at least one of a URI and a discovery header identifying said at least one other access node; receiving a response to the service request originating from the said at least one other access node, wherein the response comprises a transport layer address; and using the received transport network address to setup a user plane or control plane interface with the at least one other access node.

The request for a service offered by at least one other access node may comprise one or more parameters for use in providing the response, wherein said parameters include at least one of: a list of tracking areas, a list of slices, a list of cells, a list of PLMNs, a list of Non Public Networks, a list of closed access groups, a list of frequencies, and a list of bands.

Some example embodiments further comprise means for performing: sending a register request to a network repository function of the mobile communication system, wherein the register request registers parameters or capabilities of services of a first access node in the network repository function.

In a second aspect, this specification describes an apparatus comprising means for performing: sending (e.g. from an access node of a mobile communication system) a discovery request to a network repository function of a mobile communication system identifying a requested service, wherein the service is a transport network layer discovery service; receiving a discovery response from the network repository function in response to said discovery request, wherein the discovery response comprises a transport layer address; and using the received transport network address to setup a user plane or control plane interface with at least one other access node of the mobile communication system. Some example embodiments further comprise means for performing: sending a discovery request to a network repository function of the mobile communication system, wherein the discovery request requests for all services offered by at least one other access node; and receiving a discovery response from the network repository function in response to said discovery request, wherein the discovery response comprises a list of services offered by the other access node and information allowing the building of the corresponding URIs. The apparatus may comprises means for performing: determining whether the list of services includes a transport network layer discovery service.

Some example embodiments further comprise means for performing: sending said discovery request to the network repository function identifying the service, wherein the service is a transport network layer discovery service, in the event that the list of services is determined to include said transport network discovery service; receiving said discovery response from the network repository function in response to said discovery request, wherein the discovery response comprises a transport layer address; and using the received transport network address to setup a user plane or control plane interface with the at least one other access node.

The request for a service offered by at least one other access node may comprise one or more parameters for use in providing the response, wherein said parameters include at least one of: a list of tracking areas, a list of slices, a list of cells, a list of PLMNs, a list of Non Public Networks, a list of closed access groups, a list of frequencies, and a list of bands. Some example embodiments further comprise means for performing: sending a register request to a network repository function of the mobile communication system, wherein the register request registers parameters or capabilities of services of a first access node in the network repository function.

In a third aspect, this specification describes an apparatus (such as a network repository function) comprising means for performing: receiving a register request from each of a plurality of access nodes of a mobile communication system at a network repository function of the mobile communication system, wherein each register request registers parameters or capabilities of services of the respective access node in the network repository function; receiving, from one of said access nodes, a discovery request identifying a service offered by at least one other access node of the mobile communication system; and sending a discovery response from the network repository function in response to said discovery request, wherein the discovery response comprises a list of service identifiers or URIs.

The said means may comprise: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program configured, with the at least one processor, to cause the performance of the apparatus.

In a fourth aspect, this specification describes a method comprising: sending a request, from a first access node of a mobile communication system, for a service offered by at least one other access node, the request comprising at least one of a URI and a discovery header identifying said at least one other node; and receiving a response to the service request originating from the said at least one other access node.

The method may comprise: sending a discovery request to a network repository function of the mobile communication system, wherein the discovery request identifies the requested service; receiving a discovery response from the network repository function in response to said discovery request, wherein the discovery response comprises a list of service identifiers or URIs; and determining, based on said discovery response, a URI corresponding to the service offered by the at least one other access node, wherein sending the request for said service comprises sending said URI corresponding to the service offered. The request for the service may be sent to the at least one other access node and the response originating from the at least one other access node may be received directly from the at least one other access node. Alternatively, the request for the service may be sent from the first access node to a communication proxy including the URI corresponding to the service or a discovery header identifying the corresponding service.

The request for said service may be sent to a communication proxy and the response to said service request may be received via the communication proxy. The communication proxy may send a discovery request to a network repository function of the mobile communication system, wherein the discovery request identifies said service, if said service request does not include a URI and the communication proxy does not already know the URI of said service. The method may comprise: sending a request identifying a transport network layer discovery service offered by the at least one other access network node; receiving a response to the transport network layer discovery request originating from the said at least one other access node which response comprises a transport network layer address; and using the received transport network address to setup a user plane or control plane interface with the at least one other access node.

The method may comprise: sending a discovery request to a network repository function of the mobile communication system, wherein the discovery request requests for all services offered by at least one other access node; and receiving a discovery response from the network repository function in response to said discovery request, wherein the discovery response comprises a list of services offered by the other access node and information allowing the building of the corresponding URIs.

The method may comprise: sending a request, from a first access node of a mobile communication system, for a service offered by at least one other access node, wherein the service is a transport network layer discovery service.

The method may comprise: sending a register request to a network repository function of the mobile communication system, wherein the register request registers parameters or capabilities of services of a first access node in the network repository function. - 1-

In a fifth aspect, this specification describes a method comprising: sending (e.g. from an access node of a mobile communication system) a discovery request to a network repositoiy function of a mobile communication system identifying a requested service, wherein the service is a transport network layer discovery service; receiving a discoveiy response from the network repository function in response to said discovery request, wherein the discovery response comprises a transport layer address; and using the received transport network address to setup a user plane or control plane interface with at least one other access node of the mobile communication system. The method may comprise: sending a discovery request to a network repositoiy function of the mobile communication system, wherein the discovery request requests for all services offered by at least one other access node; and receiving a discovery response from the network repository function in response to said discovery request, wherein the discovery response comprises a list of services offered by the other access node and information allowing the building of the corresponding URIs.

The method may comprise: sending said discovery request to the network repository function identifying the service, wherein the service is a transport network layer discoveiy service, in the event that the list of services is determined to include said transport network discoveiy service; receiving said discovery response from the network repositoiy function in response to said discovery request, wherein the discovery response comprises a transport layer address; and using the received transport network address to setup a user plane or control plane interface with the at least one other access node.

The method may comprise: sending a request, from a first access node of a mobile communication system, for a service offered by at least one other access node, wherein the service is a transport network layer discoveiy service, in the event that the list of services is determined to include said transport network discovery service, and comprising at least one of a URI and a discovery header identifying said at least one other access node; receiving a response to the service request originating from the said at least one other access node, wherein the response comprises a transport layer address; and using the received transport network address to setup a user plane or control plane interface with the at least one other access node. The method may comprise: sending a register request to a network repository function of the mobile communication system, wherein the register request registers parameters or capabilities of services of a first access node in the network repository function. In a sixth aspect this specification describes a method comprising: receiving a register request from each of a plurality of access nodes of a mobile communication system at a network repository function of the mobile communication system, wherein each register request registers parameters or capabilities of services of the respective access node in the network repository function; receiving, from one of said access nodes, a discovery request identifying a service offered by at least one other access node of the mobile communication system; and sending a discovery response from the network repository function in response to said discovery request, wherein the discovery response comprises a list of service identifiers or URIs. In a seventh aspect, this specification describes computer-readable instructions which, when executed by computing apparatus, cause the computing apparatus to perform (at least) any method as described with reference to any one of fourth to sixth aspects.

In an eighth aspect, this specification describes a computer-readable medium (such as a non-transitory computer-readable medium) comprising program instructions stored thereon for performing (at least) any method as described with reference to any one of fourth to sixth aspects.

In a ninth aspect, this specification describes an apparatus comprising: at least one processor; and at least one memory including computer program code which, when executed by the at least one processor, causes the apparatus to perform (at least) any method as described with reference to any one of fourth to sixth aspects.

In a tenth aspect, this specification describes a computer program comprising instructions for causing an apparatus to perform at least the following: sending a request, from a first access node of a mobile communication system, for a service offered by at least one other access node, the request comprising at least one of a URI and a discoveiy header identifying said at least one other node; and receiving a response to the service request originating from the said at least one other access node. In an eleventh aspect, this specification describes a computer program comprising instructions for causing an apparatus to perform at least the following: sending (e.g. from an access node of a mobile communication system) a discovery request to a network repository function of a mobile communication system identifying a requested service, wherein the service is a transport network layer discovery service; receiving a discovery response from the network repository function in response to said discovery request, wherein the discovery response comprises a transport layer address; and using the received transport network address to setup a user plane or control plane interface with at least one other access node of the mobile communication system.

In a twelfth aspect, this specification describes a computer program comprising instructions for causing an apparatus to perform at least the following: receiving a register request from each of a plurality of access nodes of a mobile communication system at a network repository function of the mobile communication system, wherein each register request registers parameters or capabilities of services of the respective access node in the network repository function; receiving, from one of said access nodes, a discovery request identifying a service offered by at least one other access node of the mobile communication system; and sending a discovery response from the network repository function in response to said discovery request, wherein the discovery response comprises a list of service identifiers or URIs.

In a thirteenth aspect, this specification describes: means (such as a control module of a first access node of a mobile communication system) for sending a request for a service offered by at least one other access node, the request comprising at least one of a URI and a discovery header identifying said at least one other node; and means (such as an input of the first access node) for receiving a response to the service request originating from the said at least one other access node.

In a fourteenth aspect, this specification describes: means (such as a control module of an access node of a mobile communication system) for sending a discovery request to a network repository function of a mobile communication system identifying a requested service, wherein the service is a transport network layer discovery service; means (such as an input of the access node) for receiving a discovery response from the network repository function in response to said discovery request, wherein the discovery response comprises a transport layer address; and means (such as the control module of the access node) for using the received transport network address to setup a user plane or control plane interface with at least one other access node of the mobile communication system.

In a fifteenth aspect, this specification describes: means (such as a control module of a network repositoiy function) for receiving a register request from each of a plurality of access nodes of a mobile communication system at a network repository function of the mobile communication system, wherein each register request registers parameters or capabilities of services of the respective access node in the network repository function; means (such as the control module of the network repository function) for receiving, from one of said access nodes, a discovery request identifying a service offered by at least one other access node of the mobile communication system; and means (such as an output of the repository function) for sending a discovery response from the network repositoiy function in response to said discovery request, wherein the discovery response comprises a list of service identifiers or URIs.

Brief description of the drawings

Example embodiments will now be described, by way of example only, with reference to the following schematic drawings, in which: FIG. i is a block diagram of a system in accordance with an example embodiment;

FIGS. 2 and 3 are flow charts showing algorithms in accordance with example embodiments;

FIGS. 4 to 9 show message sequences in accordance with example embodiments;

FIGS. 10 and 11 are flow charts showing algorithms in accordance with example embodiments;

FIG. 12 shows a message sequence in accordance with an example embodiment;

FIG. 13 is a block diagram of components of a system in accordance with an example embodiment; and

FIGS. 14A and 14B show tangible media, respectively a removable non-volatile memoiy unit and a compact disc (CD) storing computer-readable code which when run by a computer perform operations according to example embodiment.

Detailed description

The scope of protection sought for various embodiments of the invention is set out by the independent claims. The embodiments and features, if any, described in the specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the invention.

In the description and drawings, like reference numerals refer to like elements throughout.

FIG. l is a block diagram of a system, indicated generally by the reference numeral io, in accordance with an example embodiment. The system io is part of a mobile communication system and includes a first gNodeB (gNB) 11, a second gNodeB (gNB) 12, and first, second and third Access and Mobility Management Functions (AMFs) 13 to 15.

Assume that, based on measurement reports from connected user equipment, the first gNB 11 determines that a cell of the second gNB 12 is candidate for a handover. The first gNB 11 may seek a direct (Xn) connection with the second gNB2. However, as indicated in FIG. 1, the Xn link between those gNBs has not been established.

One arrangement for establishing a connection between the first and second gNBs 11 and 12 is the transport network layer (TNL) address discoveiy process in which the first gNB 11 sends an NG: UPLINK RAN CONFIGURATION TRANSFER message to its corresponding AMF (e.g. the AMF 13 or the AMF 14), which includes an NG RAN Node Global Node ID of the second gNB and a request to get an Xn TNL Address. The relevant AMF routes the request towards the second gNBi2 in a NG: DOWNLINK RAN CONFIGURATION TRANSFER message either via another AMF or directly depending on the serving AMF of the second gNB 12. The gNBi2 replies using also an NG:

UPLINK RAN CONFIGURATION TRANSFER message which includes the requested Xn TNL Address of the second gNB 12, which is relayed by AMF towards gNBn also via a DOWNLINK RAN CONFIGURATION TRANSFER message. The first gNB 11 uses then the received Xn TNL Address to setup the Xn link.

An alternative to the TNL discoveiy process is to make use of the service based architecture (SBA) paradigm.

FIG. 2 is a flow chart showing an algorithm, indicated generally by the reference numeral 20, in accordance with an example embodiment. The algorithm 20 may be used to enable a first access node of a mobile communication system (such as the first gNB ii described above) to access a service provided by a second access node (such as the second gNB 12).

The algorithm 20 starts at operation 22, where the first access node of the mobile communication system sends a request for a service offered by the second access node.

As discussed further below, that request may comprise at least one of a URI and a discovery header identifying the second access node.

At operation 24 of the algorithm 20, a response to the service request is received, wherein that response originated from the second access node. The response 24 may provide the first access node with access to the requested service.

The service requested in the operation 22 maybe a handover service, but many other services could be requested. Examples of such services include: transport network layer discovery, handover preparation, handover cancellation, handover report, indication of handover success, retrieval of a UE context, release of a UE context, transfer of sequence number statuses, request for paging in access network, request for transport layer addresses, request for data forwarding, request for adding secondary node or secondary PScell/SCells, request for modification of UE context in secondary node, indication of reconfiguration complete, transfer of a radio resource control message, notification of activity in a node or a cell, request for counter check, report of radio access type data usage, request for trace, request for parameters configuration update, exchange of interference management parameters, change of cell mobility settings, resource status reporting, access and mobility indication, and energy saving mode request. The skilled person will be aware of other services that may be requested using the algorithm 20.

In order for the service request and response of the algorithm 20 to be implemented, the first access node details of the relevant service being accessed (e.g. address details) may be obtained in a discovery process.

FIG. 3 is a flow chart showing an algorithm, indicated generally by the reference numeral 30, in accordance with an example embodiment. The algorithm 30 starts at operation 32, where a discovery request is sent to a network repository function (NRF) of a mobile communication system, wherein the discoveiy request identifies the requested service. The discovery request 32 may be sent by the first access node 11, but this is not essential to all example embodiments, as discussed further below. At operation 34, a response to the discovery request is sent from the network repository function to the first access node. The discovery request response may include list of service URIs, as discussed further below.

At operation 36, the relevant service is accessed. Accessing the service may include determining, based on said discovery response received in the operation 34, a URI corresponding to the service offered by at least one other node and using the URI to access the service. The operation 36 may be implemented using the algorithm 20 described above. The discovery request may be sent directly from the relevant access node to the relevant NRF. However, as described in detail below, in some example embodiments, communications may occur via a communication proxy.

FIG. 4 shows a message sequence, indicated generally by the reference numeral 40, in accordance with an example embodiment. The message sequence 40 shows messages between a first access node 41 (such as an NG- RAN node), a second access node 42 (such as an NG- RAN node) and a network repository function (NRF) 44 of a mobile communication system. The mobile communication system also includes a service communication proxy (SCP) 43 that is not used in the message sequence 40. The message sequence 40 is an example implementations of the algorithms 20 and 30 described above.

The message sequence 40 starts with a discovery request 45 being sent from the first access node 41 to the NRF 44, thereby implementing operation 32 of the algorithm 30. The discovery request 45 may identify a service offered by the second access node 42.

In response to the discovery request, a discovery response 46 is sent from the NRF 44 to the first access node 41, thereby implementing operation 34 of the algorithm 30.

The message sequence 40 continues with the first access node sending a request 47 for a service to the second access node 42, thereby implementing operation 22 of the algorithm 20. A service response 48 is sent from the second access node 42 to the first access node 41, thereby implementing operation 24 of the algorithm 20. The request 47 and the response 48 are example implementations of the operation 36 of the algorithm 30. In the message sequence 40, the request 47 for the service is sent directly from the first access node to the second access node and the response to the request for the service is sent directly from the second access node to the first access node. As discussed in detail below, alternative arrangements are possible. The message sequence 40 may be used in circumstances where legacy X2 or Xn (inter node) interfaces are not supported (e.g. the architecture only supports service based infrastructure (SBI) interactions). The SBI architecture is leveraged to enable an NG- RAN entity 1 (the first access node 41) to discover services offered by an NG- RAN entity 2 (the second access node 42). These services may include access network functions such as handover preparation, paging, etc. (further example services are discussed elsewhere herein). In the message sequence 40, a RAN NRF 44 can be used to discover a uniform resource indicator (URI) of the SBI services supported by a remote NG RAN entity. FIG. 5 shows a message sequence, indicated generally by the reference numeral 50, in accordance with an example embodiment. The message sequence 50 shows messages between the first access node 41, the second access node 42 and the network repositoiy function (NRF) 44 of a mobile communication system. As with the message sequence 40, the mobile communication system also includes a service communication proxy (SCP) 43 that is not used in the message sequence 50. The message sequence 50 is an example implementations of the algorithms 20 and 30 described above.

The message sequence 50 starts with the first access node 41 sending a first register function 51 to register parameters and/or capabilities of services of the first access node. Similarly, the second access node 42 sends a second register function 52 to register parameters and/ or capabilities of services of the second access node. In this way, each of a plurality of NG- RAN entities can register their services (e.g. including RAN entities not shown in FIG. 5). In response to the messages 51 and 52 , the NRF 44 may register access characteristics such as the list of TAIs, list of CAG IDs, list of S-NSSAI(s) etc. supported by its respective access nodes. Of course, other characteristics instead of, or in addition to, some or all of the characteristics listed above may be registered.

In the message sequence 50, following the registration of services, the first access node 41 determines a trigger for a handover process. For example, the first access node may receive measurements from a served UE that triggers a handover towards cell 2 the second access node for this particular UE. In response, the first access nodes sends a discovery request 53 to the NRF 44 to learn the service URI offered by NG- RAN entity 2. The message 53 is an example implementation of the message 45 described above.

The first access node receives a discovery response 54 from the NRF 44 in response to the discovery request 53. The discovery response 54 includes a list of service URIs comprising the URI for a Prepare Handover (HO) service. The message 54 is an example implementation of the message 46 described above.

The first access node 41 uses the received URI to request the service by sending a suitable HTTP Post message 55 to the second access node 42. The message requests access to the Prepare Handover service. The message 55 is an example implementation of the message 47.

The second access node 42 (as the producer of the relevant service), return a suitable Prepare Handover response (as an HTTP Post Response 56) to the first access node 41. The message 56 is an example implementation of the message 48. Although the message sequence 50 is described with reference to a handover service, the principles described can be applied to other services that might be requested by the first access node 41.

FIG. 6 shows a message sequence, indicated generally by the reference numeral 60, in accordance with an example embodiment. The message sequence 60 shows messages between the first access node 41, the second access node 42, the service communication proxy (SCP) 43 and the network repository function (NRF) 44 of a mobile communication system. The message sequence 60 differs from the message sequence 40 described above in that the SCP 43 is used as a routing proxy. The message sequence 6o starts with a discovery request 61 (similar to the discovery request 45 described above) being sent from the first access node 41 to the NRF 44, thereby implementing operation 32 of the algorithm 30. The discovery request 61 may identify a service (such as a handover service) offered by the second access node 42. In response to the discovery request, a discovery response 62 (similar to the discovery response 46 described above) is sent from the NRF 44 to the first access node 41, thereby implementing operation 34 of the algorithm 30.

The message sequence 60 continues with the first access node 41 sending a request for a service 63. The service request 63 is sent to the service communication proxy (SCP) 43. The SCP sends the service request as a message 64 to the second access node 42. Thus, the messages 63 and 64 may be used to implement the functionality of the message 47 described above. A service response 65 is sent from the second access node 42 to the SCP 43 and the SCP forwards the service response 65 as a message 66 to the first access node 41. Thus, the messages 65 and 66 can be used to implement the functionality of the message 48 described above. FIG. 7 shows a message sequence, indicated generally by the reference numeral 70, in accordance with an example embodiment. The message sequence 70 shows messages between the first access node 41, the second access node 42, the service communication proxy (SCP) 43 and the network repositoiy function (NRF) 44 of a mobile communication system. The message sequence 70 is an example implementations of the algorithms 20 and 30 described above.

In the message sequence 70, the NRF 44 and the SCP 43 are used for discovery and routing, and the access nodes (such as NG- RAN entity 41) are configured to know that all NG RAN entities support services like a Prepare Handover service.

The message sequence 70 may start after the first access node 41 has determined that a service of the second access node 42 should be accessed. As discussed above, the service maybe a handover service (e.g. triggered based on measurement received from a service UE) but other example services may be accessed. The first access node sends a service request message 71 to the SCP 43. The service request message 71 may be an HTTP Post Request and may include a discovery header set to target the second access node 42 and to identify the relevant service (e.g. Prepare Handover).

Upon receiving the service request 71, the SCP 43 triggers a discovery request 72 to the RAN NRF 44 to learn the URI (e.g. IP address) at which it can reach the identified service (e.g. Prepare Handover) offered by the second access node 42. Note that is some example embodiments, the relevant URI may be included in the request 71 or may already be known to the SCP 43.

Upon receiving a response 73 to the discovery request 72 from the NRF, the SCP 43 uses the URI to send to send a service request message 74 to the second access node 42, which service request was initiated by the first access node 41.

The second access node 42, as a producer of the relevant service, returns suitable service response 75 (e.g. a Prepare Handover Response) to the SCP 43 which SCP routes the service response to the first access node (in a service response message 76). FIG. 8 shows a message sequence, indicated generally by the reference numeral 80, in accordance with an example embodiment. The message sequence 80 shows messages between the first access node 41, the second access node 42, and the network repository function (NRF) 44 of a mobile communication system. The service communication proxy (SCP) 43 is shown in FIG. 8, but is not used in the message sequence 80. The message sequence 80 is an example implementations of the algorithms 20 and 30 described above.

In the message sequence 80, SBI is leveraged to enable the second access node 42 to offer a service of transport network layer (TNL) discovery allowing a consumer (e.g. the first access node 41) to obtain an IP address allocated by the second access node which is suitable to establish a user plane or control plane interface (e.g. a “legacy Xn” interface) between the two access nodes. In a variant of the message sequence 80, a legacy X2 interface could be setup between an NG RAN node and a legacy LTE node (or, in general, a point to point interface between two access nodes). The message sequence 80 starts with the first access node 41 sending a first register function 81 to register parameters and/or capabilities of services of the first access node. Similarly, the second access node 42 sends a second register function 82 to register parameters and/ or capabilities of services of the second access node. In this way, each of a plurality of NG- RAN entities can register their services (including a TNL discovery service). The register functions 81 and 82 maybe similar to the register functions 51 and 52 described above.

The first access node 41 sends a discovery request 83 to the NRF 44. The discoveiy request identifies the TNL discoveiy service to which the first access node 41 request access.

The NRF 44 sends a discovery response 84 to the first access node 41 that includes a transport network layer address.

Alternatively, upon receiving the discovery response including a list of service URIs for TNL discovery, the first access node 41 uses the received URI to request the TNL discovery service (operation 85) from second access node 42. The second access node 42 responds to the request 85 by returning suitable Transport network layer address in a response 86 allowing subsequent setup of a user plane or control plane interface between the first and second access nodes.

FIG. 9 shows a message sequence, indicated generally by the reference numeral 90, in accordance with an example embodiment. The message sequence 90 shows messages between a eNB 91 (such as a MeNB), a gNB 92 and a network repository function (NRF) 94 of a mobile communication system. A service communication proxy (SCP) 93 is shown in FIG. 9, but is not used in the message sequence 90. In the message sequence 90, SBI is leveraged to enable the gNB (producer) to offer a service of TNL discovery allowing a consumer (e.g. a MeNB) to get an IP address allocated by the gNB which is suitable to establish a user plane or control plane interface (e.g. a “legacy X2” interface) between the two RAN nodes. The message sequence 90 starts with the eNB 91 sending a first register function 101 to register parameters and/or capabilities of services of the eNB. Similarly, the gNB 92 sends a second register function 102 to register parameters and/or capabilities of services of the gNB. In this way, each of a plurality of NG- RAN entities can register their services (including a TNL discovery service). The register functions 101 and 102 maybe similar to the functions 51 and 81, and 52 and 82 respectively.

The eNB 91 sends a discovery request 103 to the NRF 94. The discovery request identifies the TNL discovery service to which the eNB requests access.

The NRF 94 sends a discovery response 104 to the eNB 91 that includes a transport network layer address.

Alternatively, upon receiving the discovery response 104, the eNB 91 uses the received URI to request the service of TNL discovery from the gNB 92 (by sending HTTP Post message 105 to the gNB 92).

The gNB 92, as a producer of the requested service, returns suitable Transport network layer address to the eNB 91 in a Post response message 106, allowing subsequent setup of a user plane or control plane interface between the eNB 91 and the gNB 92. FIG. 10 is a flow chart showing an algorithm, indicated generally by the reference numeral 110, in accordance with an example embodiment.

The algorithm 110 starts at operation 111, where a discovery request is sent from a first access node (such as the first access node 41) to a network repository function (such as the NRF 44) of the mobile communication system. The discovery request 111 is a request for all services offered by at least one other access node (such as the second access node 42).

At operation 112, a discovery response is received (at the first access node) from the network repositoiy function in response to said discovery request. The discoveiy response comprises a list of services offered by the other access node and information allowing the building of the corresponding URIs

In the event that it is determined that the list of services includes a transport network layer (TNL) discoveiy service, then the algorithm 110 proceeds to operation 113, where a discovery request is sent to the network repository function identifying the transport network layer discovery service. The operation 113 may, for example, be implemented by the discovery request 83 described above.

At operation 114, a discovery response is received from the network repository function in response to said discovery request. The discovery response comprises a transport layer address (and may be implemented by the discovery response 84 described above).

On receipt of the discovery response, the received transport network address is used, in operation 115, to setup a user plane or control plane interface with the at least one other access node. The operation 115 may be implemented by the request 85 and the response 86 described above.

FIG. 11 is a flow chart showing an algorithm, indicated generally by the reference numeral 120, in accordance with an example embodiment. The algorithm 120 is an alternative to the algorithm 110 described above.

The algorithm 120 starts at operation 121, where a discovery request is sent from a first access node (such as the first access node 41) to a network repository function (such as the NRF 44) of the mobile communication system. The discovery request 111 is a request for all services offered by at least one other access node (such as the second access node 42).

At operation 122, a discovery response is received (at the first access node) from the network repository function in response to said discovery request. The discovery response comprises a list of services offered by the other access node and information allowing the building of the corresponding URIs

The operations 121 and 122 may therefore be the same as the operations 111 and 112 described above.

In the event that it is determined that the list of services includes a transport network layer (TNL) discovery service, then the algorithm 120 proceeds to operation 123, where the TNL discovery service is requested. In response to the TNL request, a suitable Transport network layer address is provided in a response 124 allowing subsequent setup of a user plane or control plane interface between the first and second access nodes in an operation 125. FIG. 12 shows a message sequence, indicated generally by the reference numeral 130. in accordance with an example embodiment. The message sequence iso.covers the case where an access node may have lower granularity. In particular, the above-described embodiments illustrate one possible case that an access node is realized as a single entity or node. In the message sequence 130, the above-described embodiments are generalized, where an access node entity can comprise a number of network functions (NFs), where each network function can register at a network repository function (NRF), e.g., the services offered by an NF. The AN NRF can be centralized, e.g., one AN NRF for a set of access nodes or distributed, e.g., one AN NRF per access node. In the message sequence 130, an access node is exemplified as a gNB and the case of one NRF per AN node is shown. This generalization enables components within one AN node to benefit from similar services as described above from a registration and discovery towards an NRF which is at an AN node level.

The main steps of the message sequence 130 are as follows. NF Registration at AN Node NRFs: A gNB 1 and a gNB 2 have NRFs which receive the registration of the services offered by the components/NFs of the gNB 1 and gNB2, e.g., from capability network function (NF). A capability NF in an AN Node (see gNBi and gNB2) is configured by 0AM with the information relevant for the AN node, e.g., TAIs and supported slices. The functionality of such a capability NF can be part of the NRF, as well.

Detection of a new cell: A neighbour cell relation (NCR) NF maybe implemented in an AN node. This NF can be utilized to detect neighbour cells, e.g., based on the UE measurements. When a neighbour cell gNB2 is detected by the NCR NF, the NCR NF informs the gNBi NRF with the gNB2 information, e.g., CGI.

Discovery Request: In case the service requested by the consumer is outside gNB, a discovery request can be directed to the target NRF (see gNB2 NRF) e.g. via an service communication proxy (SCP). Discovery Response: The discovery response from the target gNB2 NRF can be sent to the source gNBi NRF e.g. via the SCP.

Inter-AN service-based communication: After the discovery steps, the gNBi and gNB2 NFs can consume the offered services, as exemplified in the embodiments beforehand.

For completeness, FIG. 13 is a schematic diagram of components of one or more of the example embodiments described previously, which hereafter are referred to generically as a processing system 300. The processing system 300 may, for example, be the apparatus referred to in the claims below.

The processing system 300 may have a processor 302, a memory 304 closely coupled to the processor and comprised of a RAM 314 and a ROM 312, and, optionally, a user input 310 and a display 318. The processing system 300 may comprise one or more network/apparatus interfaces 308 for connection to a network/ apparatus, e.g. a modem which may be wired or wireless. The network/ apparatus interface 308 may also operate as a connection to other apparatus such as device/apparatus which is not network side apparatus. Thus, direct connection between devices/apparatus without network participation is possible.

The processor 302 is connected to each of the other components in order to control operation thereof. The memory 304 may comprise a non-volatile memory, such as a hard disk drive (HDD) or a solid state drive (SSD). The ROM 312 of the memory 304 stores, amongst other things, an operating system 315 and may store software applications 316. The RAM 314 of the memory 304 is used by the processor 302 for the temporary storage of data. The operating system 315 may contain code which, when executed by the processor implements aspects of the algorithms and message sequence 20, 30, 40, 50, 60, 70, 80, 90, 110, 120 and 130 described above. Note that in the case of small device/apparatus the memory can be most suitable for small size usage i.e. not always a hard disk drive (HDD) or a solid state drive (SSD) is used. The processor 302 may take any suitable form. For instance, it may be a microcontroller, a plurality of microcontrollers, a processor, or a plurality of processors. The processing system 300 maybe a standalone computer, a server, a console, or a network thereof. The processing system 300 and needed structural parts may be all inside device/apparatus such as loT device/apparatus i.e. embedded to very small size.

In some example embodiments, the processing system 300 may also be associated with external software applications. These may be applications stored on a remote server device/apparatus and may run partly or exclusively on the remote server device/apparatus. These applications maybe termed cloud-hosted applications. The processing system 300 may be in communication with the remote server device/apparatus in order to utilize the software application stored there.

FIGS. 14A and 14B show tangible media, respectively a removable memory unit 365 and a compact disc (CD) 368, storing computer-readable code which when run by a computer may perform methods according to example embodiments described above. The removable memory unit 365 may be a memory stick, e.g. a USB memory stick, having internal memory 366 storing the computer-readable code. The internal memory 366 may be accessed by a computer system via a connector 367. The CD 368 may be a CD-ROM or a DVD or similar. Other forms of tangible storage media may be used.

Tangible media can be any device/apparatus capable of storing data/information which data/information can be exchanged between devices/apparatus/network.

Embodiments of the present invention may be implemented in software, hardware, application logic or a combination of software, hardware and application logic. The software, application logic and/ or hardware may reside on memory, or any computer media. In an example embodiment, the application logic, software or an instruction set is maintained on any one of various conventional computer-readable media. In the context of this document, a “memory” or “computer-readable medium” may be any non-transitory media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer. Reference to, where relevant, “computer-readable medium”, “computer program product”, “tangibly embodied computer program” etc., or a “processor” or “processing circuitry” etc. should be understood to encompass not only computers having differing architectures such as single/multi-processor architectures and sequencers/parallel architectures, but also specialised circuits such as field programmable gate arrays FPGA, application specify circuits ASIC, signal processing devices/apparatus and other devices/apparatus. References to computer program, instructions, code etc. should be understood to express software for a programmable processor firmware such as the programmable content of a hardware device/apparatus as instructions for a processor or configured or configuration settings for a fixed function device/ apparatus, gate array, programmable logic device/apparatus, etc.

If desired, the different functions discussed herein may be performed in a different order and/ or concurrently with each other. Furthermore, if desired, one or more of the above-described functions may be optional or may be combined. Similarly, it will also be appreciated that the flow diagrams and message sequences of Figures 2 to 12 are examples only and that various operations depicted therein may be omitted, reordered and/ or combined. It will be appreciated that the above described example embodiments are purely illustrative and are not limiting on the scope of the invention. Other variations and modifications will be apparent to persons skilled in the art upon reading the present specification. Moreover, the disclosure of the present application should be understood to include any novel features or any novel combination of features either explicitly or implicitly disclosed herein or any generalization thereof and during the prosecution of the present application or of any application derived therefrom, new claims may be formulated to cover any such features and/ or combination of such features.

Although various aspects of the invention are set out in the independent claims, other aspects of the invention comprise other combinations of features from the described example embodiments and/ or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims. It is also noted herein that while the above describes various examples, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications which may be made without departing from the scope of the present invention as defined in the appended claims.

Claims

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Claims

1. An apparatus, comprising means for performing: sending a request, from a first access node of a mobile communication system, for a service offered by at least one other access node, the request comprising at least one of a URI and a discovery header identifying said at least one other access node; and receiving a response to the service request originating from the said at least one other access node. 2. An apparatus as claimed in claim 1, wherein the apparatus further comprises means for performing: sending a discovery request to a network repository function of the mobile communication system, wherein the discovery request identifies the requested service; receiving a discovery response from the network repository function in response to said discovery request, wherein the discovery response comprises a list of service identifiers or URIs; and determining, based on said discovery response, a URI corresponding to the service offered by the at least one other access node, wherein sending the request for said service comprises sending said URI corresponding to the service offered.

3. An apparatus as claimed in claim 1 or claim 2, wherein the request for the service is sent to the at least one other access node and the response originating from the at least one other access node is received directly from the at least one other access node.

4. An apparatus as claimed in claim 1 or claim 2, wherein the request for the service is sent from the first access node to a communication proxy including the URI corresponding to the service or a discovery header identifying the corresponding service, wherein the apparatus further comprises means for performing: receiving a response to the service request at the first access node from said at least one other access node via the communication proxy.

5- An apparatus as claimed in claim 1, wherein: the request for said service is sent to a communication proxy; and the response to said service request is received via the communication proxy, wherein the communication proxy sends a discovery request to a network repository function of the mobile communication system, wherein the discovery request identifies said service, if said service request does not include a URI and the communication proxy does not already know the URI of said service.

6. An apparatus as claimed in any one of claims 1 to 5, wherein the requested service is one of: transport network layer discovery, handover preparation, handover cancellation, handover report, indication of handover success, retrieval of a UE context, release of a UE context, transfer of sequence number statuses, request for paging in access network, request for transport layer addresses, request for data forwarding, request for adding secondary node or secondary PScell/SCells, request for modification of UE context in secondary node, indication of reconfiguration complete, transfer of a radio resource control message, notification of activity in a node or a cell, request for counter check, report of radio access type data usage, request for trace, request for parameters configuration update, exchange of interference management parameters, change of cell mobility settings, resource status reporting, access and mobility indication, and energy saving mode request.

7. An apparatus as claimed in claim 1 to 6, wherein the apparatus comprises means for performing: sending a request identifying a transport network layer discoveiy service offered by the at least one other access network node; receiving a response to the transport network layer discovery request originating from the said at least one other access node which response comprises a transport network layer address; and using the received transport network address to setup a user plane or control plane interface with the at least one other access node.

8. An apparatus comprising means for performing: sending a discovery request to a network repositoiy function of a mobile communication system identifying a requested service, wherein the service is a transport network layer discoveiy service; receiving a discovery response from the network repository function in response to said discovery request, wherein the discovery response comprises a transport layer address; and using the received transport network address to setup a user plane or control plane interface with at least one other access node of the mobile communication system. . An apparatus as claimed in any one of claims 1 to 8, wherein the apparatus comprises means for performing: sending a discovery request to a network repository function of the mobile communication system, wherein the discovery request requests for all services offered by at least one other access node; and receiving a discovery response from the network repository function in response to said discovery request, wherein the discovery response comprises a list of services offered by the other access node and information allowing the building of the corresponding URIs. 10. An apparatus as claimed in claim 9, wherein the apparatus comprises means for performing: determining whether the list of services includes a transport network layer discovery service.

11. An apparatus as claimed in claim 10, further comprising means for performing: sending a request, from a first access node of a mobile communication system, for a service offered by at least one other access node, wherein the service is a transport network layer discovery service, in the event that the list of services is determined to include said transport network discovery service, and comprising at least one of a URI and a discovery header identifying said at least one other access node; receiving a response to the service request originating from the said at least one other access node, wherein the response comprises a transport layer address; and using the received transport network address to setup a user plane or control plane interface with the at least one other access node. 12. An apparatus as claimed in any one of claims 1 to 11, wherein the request for a service offered by at least one other access node comprises one or more parameters for use in providing the response, wherein said parameters include at least one of: a list of tracking areas, a list of slices, a list of cells, a list of PLMNs, a list of Non Public Networks, a list of closed access groups, a list of frequencies, and a list of bands. - 29 -

13. An apparatus as claimed in any one of claims 1 to 12, further comprising means for performing: sending a register request to a network repository function of the mobile communication system, wherein the register request registers parameters or capabilities of services of a first access node in the network repository function.

14. An apparatus comprising means for performing: receiving a register request from each of a plurality of access nodes of a mobile communication system at a network repository function of the mobile communication system, wherein each register request registers parameters or capabilities of services of the respective access node in the network repository function; receiving, from one of said access nodes, a discovery request identifying a service offered by at least one other access node of the mobile communication system; and sending a discovery response from the network repository function in response to said discovery request, wherein the discovery response comprises a list of service identifiers or URIs.

15. A method comprising: sending a request, from a first access node of a mobile communication system, for a service offered by at least one other access node, the request comprising at least one of a URI and a discovery header identifying said at least one other node; and receiving a response to the service request originating from the said at least one other access node.

16. A computer program comprising instructions for causing an apparatus to perform at least the following: sending a request, from a first access node of a mobile communication system, for a service offered by at least one other access node, the request comprising at least one of a URI and a discovery header identifying said at least one other node; and receiving a response to the service request originating from the said at least one other access node.