WO2024172736A1

WO2024172736A1 - Network nodes and methods for handling signaling messages

Info

Publication number: WO2024172736A1
Application number: PCT/SE2024/050144
Authority: WO
Inventors: Serban Purge; Luca LUNARDI; Angelo Centonza; Julien Muller
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2023-02-16
Filing date: 2024-02-15
Publication date: 2024-08-22

Abstract

Network nodes and method for handling message signaling between a first network node (811) and a second network node (812) in a wireless communication network are provided. The first network node (811) sends (901) an interface setup request message to the second network node (812), wherein the interface setup request message comprises one or more parameters indicating characteristics of signaling messages of the first network node (811). The first network node receives a response from the second network node (812), wherein the response comprises one or more parameters indicating any one of: acceptance of the characteristics of signaling messages of the first network node (811), a cause for failure of receiving the interface setup request message, characteristics of signaling messages of the second network node (812).

Description

NETWORK NODES AND METHODS FOR HANDLING SIGNALING MESSAGES

TECHNICAL FIELD

Embodiments herein relate to network nodes and methods therein for handling signaling messages. In particular, they relate to handling large application protocols signaling messages between two network nodes in wireless communication networks.

BACKGROUND

In a typical wireless communication network, wireless devices, also known as wireless communication devices, mobile stations, user equipment (UE), communicate via a Radio Access Network (RAN) to one or more core networks (CN). The RAN covers a geographical area which is divided into service areas or cell areas, which may also be referred to as a beam or a beam group, with each service area or cell area being served by a radio network node such as a radio access node e.g., a Wi-Fi access point or a radio base station (RBS), which in some networks may also be denoted, for example, a “NodeB” or “eNodeB” or “eNB” or “gNB”. A service area or cell area is a geographical area where radio coverage is provided by the radio network node. The radio network node communicates over an air interface operating on radio frequencies with the wireless communication device within a range of the radio network node.

A Universal Mobile Telecommunications System (UMTS) is a third generation (3G) telecommunication network, which evolved from the second generation (2G) Global System for Mobile Communications (GSM). Specifications for the Evolved Packet System (EPS), also called a Fourth Generation (4G) network or Long Term Evolution (LTE) have been completed within the 3rd Generation Partnership Project (3GPP) and this work continues in the coming 3GPP releases, for example to specify a Fifth Generation (5G) New Radio (NR) network, Next Generation (NG) and upcoming releases.

The current 5G RAN, the Next-Generation Radio Access Network (NG-RAN) architecture is depicted and described in TS 38.401 v17.2.0 as shown in Figure 1.

The NG-RAN consists of a set of gNBs connected to the 5G Core network (5GC) through the NG interface.

NOTE: As specified in TS 38.300, NG-RAN could also consist of a set of ng-eNBs, an ng-eNB may consist of an ng-eNB-Control Unit (ng-eNB-CU) and one or more ng-eNB- Distributed Units (ng-eNB-DUs). An ng-eNB-CU and an ng-eNB-DU is connected via W1 interface. The general principle described in this clause also applies to ng-eNB and W1 interface, if not explicitly specified otherwise.

• An gNB can support Frequency-division duplexing (FDD) mode, Time Division Duplexing (TDD) mode or dual mode operation.

• gNBs can be interconnected through the Xn interface.

• A gNB may consist of a gNB-Cll and one or more gNB-DU(s). A gNB-Cll and a gNB-Dll is connected via F1 interface.

• One gNB-Dll is connected to only one gNB-Cll.

NOTE: In case of network sharing with multiple cell ID broadcast, each Cell Identity associated with a subset of PLMNs corresponds to a gNB-Dll and the gNB-Cll it is connected to, i.e. the corresponding gNB-DUs share the same physical layer cell resources.

NOTE: For resiliency, a gNB-Dll may be connected to multiple gNB-CUs by appropriate implementation.

• NG, Xn and F1 are logical interfaces.

For NG-RAN, the NG and Xn-C interfaces for a gNB consisting of a gNB-Cll and gNB-DUs, terminate in the gNB-CU. For EN-DC, i.e. Evolved-Universal Terrestrial Radio Access-New Radio (E-UTRA NR) Dual connectivity (DC), the S1-U and X2-C interfaces for a gNB consisting of a gNB-CU and gNB-DUs, terminate in the gNB-CU. The gNB-CU and connected gNB-DUs are only visible to other gNBs and the 5GC as a gNB. A possible deployment scenario is described in Annex A of TS 38.401.

The node hosting user plane part of NR Packet Data Convergence Protocol (PDCP) e.g. gNB-CU, gNB-CU-UP, and for EN-DC, MeNB or SgNB depending on the bearer split, shall perform user inactivity monitoring and further informs its inactivity or (re)activation to the node having C-plane connection towards the core network, e.g. over E1 , X2. The node hosting NR RLC, e.g. gNB-DU, may perform user inactivity monitoring and further inform its inactivity or (re)activation to the node hosting control plane, e.g. gNB-CU or gNB-CU-CP.

UL PDCP configuration, i.e. how the UE uses the UL at the assisting node, is indicated via X2-C for EN-DC, Xn-C for NG-RAN and F1-C. Radio Link Outage/Resume for DL and/or UL is indicated via X2-U for EN-DC, Xn-U for NG-RAN and F1-U.

The NG-RAN is layered into a Radio Network Layer (RNL) and a Transport Network Layer (TNL).

The NG-RAN architecture, i.e. the NG-RAN logical nodes and interfaces between them, is defined as part of the RNL. For each NG-RAN interface, NG, Xn, F1 , the related TNL protocol and the functionality are specified. The TNL provides services for user plane transport, signaling transport.

In NG-Flex configuration, each NG-RAN node is connected to all Access and Mobility Management Functions (AMFs) of AMF Sets within an AMF Region supporting at least one slice also supported by the NG-RAN node. The AMF Set and the AMF Region are defined in 3GPP TS 23.501.

If security protection for control plane and user plane data on TNL of NG-RAN interfaces has to be supported, NDS/IP 3GPP TS 33.501 shall be applied.

The overall architecture for separation of gNB-CU-CP and gNB-CU-UP is depicted in Figure 2 and specified in TS 37.483.

A gNB may consist of a gNB-CU-CP, multiple gNB-CU-UPs and multiple gNB-DUs.

The gNB-CU-CP is connected to the gNB-DU through the F1-C interface.

The gNB-CU-UP is connected to the gNB-DU through the F1-U interface.

The gNB-CU-UP is connected to the gNB-CU-CP through the E1 interface.

One gNB-DU is connected to only one gNB-CU-CP.

One gNB-CU-UP is connected to only one gNB-CU-CP.

NOTE 1 : For resiliency, a gNB-DU and/or a gNB-CU-UP may be connected to multiple gNB-CU-CPs by appropriate implementation.

One gNB-DU can be connected to multiple gNB-CU-UPs under the control of the same gNB-CU-CP.

One gNB-CU-UP can be connected to multiple DUs under the control of the same gNB-CU-CP.

NOTE 2:The connectivity between a gNB-CU-UP and a gNB-DU is established by the gNB-CU-CP using Bearer Context Management functions.

NOTE 3:The gNB-CU-CP selects the appropriate gNB-CU-UP(s) for the requested services for the UE. In case of multiple CU-UPs they belong to same security domain as defined in TS 33.210.

NOTE 4: Data forwarding between gNB-CU-UPs during intra-gNB-CU-CP handover within a gNB may be supported by Xn-U.

Artificial Intelligence/Machine Learning (AI/ML) for NG-RAN in 3GPP

3GPP TR 37.817, Version 17.0.0, Study on enhancement for data collection for NR and ENDC, provides descriptions of principles for RAN intelligence enabled by Al, a functional framework as depicted in Figure 3, outlining Al functionality as well as inputs and outputs for Al enabled optimization, as well as use cases and solutions of Al enabled RAN. The study is based on the current architecture and interfaces. The analyzed use cases are Network Energy Saving, Load Balancing, and Mobility Optimization, and for all those AI/ML Model Training is located either in the Operations, Administration and Maintenance (OAM) node or in the gNB node, specifically gNB-CU.

Figure 4, Figure 5 and Figure 6 each depict the case where Model Training is located in the gNB for the three use cases. Note that AI/ML Model Inference is always located in the NG-RAN.

TR 37.817 mentions the use of “Feedback”. Section 4.2 of TR 37.817 states:

Actor is a function that receives the output from the Model Inference function and triggers or performs corresponding actions. The Actor may trigger actions directed to other entities or to itself.

Feedback: Information that may be needed to derive training data, inference data or to monitor the performance of the AI/ML Model and its impact to the network through updating of KPIs and performance counters.

KPI, key performance indicator, is a type of performance measurement. KPIs are used to provide a focus for strategic and operational improvement, create an analytical basis for decision making, and help focus attention on what matters most.

As described below, NG-RAN node 1 , which hosts the Model Inference, requires feedback related to the Network Energy Saving, Load Balancing, or Mobility Optimization action taken by NG-RAN node 1 from NG-RAN node 2, which is any neighboring NG-RAN node of NG-RAN node 1.

Section 5.1.2.6, Section 5.2.2.6, and Section 5.3.2.6 in TR 37.817 list the type of feedback given for AI/ML-based Network Energy Saving, Load Balancing, and Mobility Optimization. In one example, the action taken by NG-RAN node 1, i.e. serving NG-RAN node, entails a handover of at least one UE to NG-RAN node 2, i.e. target NG-RAN node. In this example, the feedback includes UE performance e.g., of handed-over UEs, affected by the action, including Quality of Service (QoS) parameters such throughput, bitrate, packet delay, latency, packet loss, etc. Additional details can be found in TR 37.817.

Section 5.1.2.3 of TR 37.817 for the Network Energy Saving use case states (See Figure 4):

AI/ML Model Training and AI/ML Model Inference at NG-RAN.

In this solution, NG-RAN is responsible for model training and generates energy saving decisions.

Step 0: NG-RAN node 2 is assumed to have an AI/ML model optionally, which can provide NG-RAN node 1 with input information. Step 1: NG-RAN node 1 configures the measurement information on the UE side and sends configuration message to UE to perform measurement procedure and reporting.

Step 2: The UE collects the indicated measurement(s), e.g., UE measurements related to RSRP, RSRQ, SINR of serving cell and neighboring cells.

Step 3 : The UE sends the measurement report(s) to NG-RAN node 1 including the required measurement result.

Step 4: NG-RAN node 2 sends the required input data to NG-RAN node 1 for model training of AI/ML-based network energy saving.

Step 5 : NG-RAN node 1 trains AI/ML model for AI/ML-based energy saving based on collected data. NG-RAN node 2 is assumed to have AI/ML model for AI/ML-based energy saving optionally, which can also generate predicted results/actions.

Step 6: NG-RAN node 2 sends the required input data to NG-RAN node 1 for model inference of AI/ML-based network energy saving.

Step 7 : UE sends the UE measurement report(s) to NG-RAN node 1.

Step 8: Based on local inputs of NG-RAN node 1 and received inputs from NG-RAN node 2, NG-RAN node 1 generates model inference output (e.g., energy saving strategy, handover strategy, etc).

Step 9: NG-RAN node 1 executes Network energy saving actions according to the model inference output. NG-RAN node 1 may select the most appropriate target cell for each UE before it performs handover, if the output is handover.

Section 5.1.2.6 of TR 37.817 for the Network Energy Saving use case states:

Feedback of AI/ML-based Network Energy Saving

To optimize the performance of an AI/ML-based network energy saving model, the following feedback can be considered to be collected from NG-RAN nodes:

• Resource status of neighboring NG-RAN node/s

• Energy efficiency

• UE performance affected by the energy saving action (e.g., handed-over UEs), including bitrate, packet loss and latency

• System KPIs (e.g., throughput, delay, RLF of current and neighboring NG-RAN node/s)

Section 5.2.2.3 of TR 37.817 for the Load Balancing use case states:

AI/ML Model Training and AI/ML Model Inference in a NG-RAN node

A high-level signaling flow for the AI/ML use case related to Load Balancing with Model Training and Model Inference in a NG-RAN node is shown in Figure 5. Step 0: NG-RAN node 2 is assumed to have an AI/ML model optionally, which can provide NG-RAN node 1 with useful input information, such as predicted resource status, etc.

Step 1 : The NG-RAN node 1 configures UE to provide measurements and/or location information( e.g., RRM measurements, MDT measurements, velocity, position).

Step 2: The UE collects the indicated measurement(s), e.g., UE measurements related to RSRP, RSRQ, SINR of the serving cell and neighbouring cells.

Step 3 : The UE reports to NG-RAN node 1 the requested measurements and/or location information (e.g., UE measurements related to RSRP, RSRQ, SINR of serving cell and neighbouring cells, velocity, position).

Step 4: The NG-RAN node 1 receives from the neighbouring NG-RAN node 2 the input information for load balancing model training.

Step 5 : An AI/ML Model Training is located at NG-RAN node 1. The required measurements and input data from other NG-RAN nodes are leveraged to train the AI/ML model.

Step6: NG-RAN node 1 receives UE measurements and/or location information.

Step? : NG-RAN node 1 can receive from the neighbouring NG-RAN node 2 the input information for load balancing model inference.

Step 8: NG-RAN node 1 performs model inference and generate Load Balancing predictions or decisions.

Step 9: NG-RAN node 1 may take Load Balancing actions and the UE is moved from NG- RAN node 1 to NG-RAN node 2.

Step 10: NG-RAN node 2 sends feedback information to NG-RAN node 1 (e.g., resource status updates after load balancing, etc.).

Section 5.2.2.6 of TR 37.817 for the Load Balancing use case states:

Feedback of AI/ML-based Load Balancing

To optimize the performance of an AI/ML-based load balancing model, the following feedback can be considered to be collected from NG-RAN nodes:

• UE performance information from target NG-RAN node (for those UEs handed over from source NG-RAN node)

• Resource status information updates from target NG-RAN node

Section 5.3.2.3 of TR 37.817 for the Mobility Optimization use case states (See Figure 6):

AI/ML Model Training and AI/ML Model Inference in a NG-RAN node Step 0: NG-RAN node 2 is assumed to optionally have an AI/ML model, which can generate required input such as resource status and utilization prediction/estimation etc.

Step 1 : NG-RAN node 1 configures the measurement information on the UE side and sends configuration message to UE including configuration information.

Step 2: UE collects the indicated measurement, e.g., UE measurements related to RSRP, RSRQ, SINR of serving cell and neighbouring cells.

Step 3 : UE sends measurement report message to NG-RAN node 1 including the required measurement.

Step 4: The NG-RAN node 1 obtains the input data for training from the NG-RAN node2, where the input data fortraining includes the required input information from the NG-RAN node 2. If the NG-RAN node 2 executes the AI/ML model, the input data for training can include the corresponding inference result from the NG-RAN node 2.

Step 5: Model training. Required measurements are leveraged to training AI/ML model for mobility optimization.

Step 6: NG-RAN nodel obtains the measurement report as inference data for real-time UE mobility optimization.

Step 7 : The NG-RAN node 1 obtains the input data for inference from the NG-RAN node 2 for UE mobility optimization, where the input data for inference includes the required input information from the NG-RAN node 2. If the NG-RAN node 2 executes the AI/ML model, the input data for inference can include the corresponding inference result from the NG-RAN node 2.

Step 8: Model Inference. Required measurements are leveraged into Model Inference to output the prediction, including e.g., UE trajectory prediction, target cell prediction, target NG- RAN node prediction, etc.

Step 9: According to the prediction, recommended actions or configuration, the NG-RAN node 1, the target NG-RAN node (represented by NG-RAN node 2 of this step in the flowchart), and UE perform the Mobility Optimization / handover procedure to hand over UE from NG-RAN node 1 to the target NG-RAN node.

Step 10: The NG-RAN node 2 sends feedback information after mobility optimization action to the NG-RAN node 1.

Note: UE mobility information for training purposes is only sent to gNBs that requested such information or when triggered.

Section 5.3.2.6 of TR 37.817 for the Mobility Optimization use case states:

Feedback of AI/ML-based Mobility Optimization To optimize the performance of an AI/ML-based mobility optimization model, the following data is required as feedback data:

• QoS parameters such as throughput, packet delay, etc. of handed-over UE

• Resource status information updates from target NG-RAN node

• Performance information from target NG-RAN node

.The details of the performance information are to be discussed during normative work phase.

As stated above, TR 37.817 also studies the case where the AI/ML Model Training is located in the OAM and the AI/ML Model Inference is located at NG-RAN i.e., gNB. In this case, the feedback is signaled from both NG-RAN node 1 and the NG-RAN node 2 to the OAM but is the same as described above.

TR 37.817 [1] also mentions the use of so-called “Model Performance Feedback”.

Section 4.2 of TR 37.817 states:

Model Inference is a function that provides AI/ML model inference output (e.g. predictions or decisions). Model Inference function may provide Model Performance Feedback to Model Training function when applicable. The Model Inference function is also responsible for data preparation (e.g. data pre-processing and cleaning, formatting, and transformation) based on Inference Data delivered by a Data Collection function, if required. o Output: The inference output of the AI/ML model produced by a Model Inference function.

■ Note: Details of inference output are use case specific. o Model Performance Feedback: It may be used for monitoring the performance of the AI/ML model, when available.

■ Note: Details of the Model Performance Feedback process are out of RAN3 scope.

As can be seen from TR 37.817, the Model Performance Feedback is intended to provide an indication on the performance of the AI/ML model, but it has not been defined yet.

Regarding the procedures used by the NG-RAN nodes to request and report feedback information the following agreements have been made during RAN3 #117-bis-e and #118 meetings (See RAN3_117bis-e_agenda_20221018_EOM1 ,

RAN3_118_agenda_20221118_EOM):

•Introduce a new Class 1 procedure for initiating the reporting of AI/ML Related

Information and a Class 2 procedure for Data Reporting of AI/ML Related Information. • Reporting options for the new procedure used for AI/ML Related Information to be evaluated on a case-by-case basis. Possible reporting options are one-time and periodic reporting.

• The new procedure is non-U E associated procedure. If needed, the procedure can be used to capture UE-associated information.

• Procedures used for AI/ML support in the NG-RAN shall be “data type agnostic”.

A possible implementation of the above agreements is depicted in R3-225510 and shown in Figure 7.

In the message sequence chart depicted in Figure 7, each step can be described as follows:

0. NG-RAN Node 1 is assumed to host a trained model.

1. NG-RAN Node 1 signals to NG-RAN Node 2 an Xn SETUP REQUEST message.

2. NG-RAN Node 2 signals to NG-RAN Node 1 an Xn SETUP RESPONSE message.

3. If needed, NG-RAN Node 1 configures measurements at the UE and receives measurement reports accordingly.

4. In order to configure the process of input data reporting, NG-RAN node 1 signals to NG-RAN Node 2 the Xn: AI/ML Assistance Data Request message.

5. NG-RAN Node 2 replies with the Xn: AI/ML Assistance Data Response message, where it accepts reporting of the requested information.

6. NG-RAN Node 2 signals the Xn: AI/ML Assistance Data Update message to report the information requested to NG-RAN Node 1.

7. NG-RAN Node 1 may perform AI/ML based inference on the basis of the inputs received and of other information.

8. In order to configure the process of output data reporting, NG-RAN node 2 signals to NG-RAN Node 1 the Xn: AI/ML Assistance Data Request message.

9. NG-RAN Node 1 replies with the Xn: AI/ML Assistance Data Response message, where it accepts reporting of the requested information.

10. NG-RAN Node 1 signals the Xn: AI/ML Assistance Data Update message to report the information requested to NG-RAN Node 2.

11. In order to configure the process of feedback data reporting, NG-RAN node 1 signals to NG-RAN Node 2 the Xn: AI/ML Assistance Data Request message.

12. NG-RAN Node 2 replies with the Xn: AI/ML Assistance Data Response message, where it accepts reporting of the requested information. 13. NG-RAN Node 2 signals the Xn: AI/ML Assistance Data Update message to report the information requested to NG-RAN Node 1.

The background given on AI/ML support at the NG-RAN enables an understanding of how data exchange between RAN nodes may become intense both in signaling messages frequency terms and/or in terms of the size of messages reporting AI/ML related data.

Therefore an improved technique is needed for handling high amount of messages and high message exchanging frequency or rate between network nodes for supporting AI/ML functions.

SUMMARY

As part of developing embodiments herein problems were identified and will first be discussed.

It may be understood that any implementation of RAN nodes and functions would have limitations in terms of the size of interface messages that can be processed and in terms of interface signaling message frequency.

For example, an implementation may have limitation on the size of a message that can be decoded in ASN.1 coding language, which is one of the coding languages for network interfaces in 3GPP. As another example, an implementation may have limitation on the size of a message that can be received at transport protocol endpoint. In both examples, a too large message would result in the incapability at the receiving node to decode the message.

Hence the problem is that the current technology does not enable two network nodes to negotiate or agree on an optimal size and/or frequency of the messages exchanged on the interface between the two network nodes. Therefore, in some cases when the size or the frequency of exchanging messages over the interface between the two network nodes gets too high, the receiving node may have problems with decoding and processing the messages. The latter may result in the failure of the procedure the message belongs to.

Further, even without a negotiation between the peer nodes involved in the signaling, the current technology does not enable a network node to split a message to be sent in several fragments if the size of the message is too large or to combine several messages to be sent in a single message in order to reduce the frequency of the messages over the interface. Therefore, it is an object of embodiments herein to provide an improved method for handling signaling message between two network nodes in a wireless communication network to overcome the limitations with the prior art.

According to one aspect of the embodiments herein, the object is achieved by a first network node and method therein for handling message signaling to a second network node in a wireless communication network.

The first network node initiates an interface setup procedure by sending an interface setup request message to a second network node. The interface setup request message comprises one or more parameters indicating characteristics of signaling messages of the first network node. For examples, the first network node may specify in the request message one or more parameters indicating any one or more of the maximum size for a message that can be sent or received over the interface by the first network node, the maximum message sending or receiving rate, the maximum message sending or receiving frequency, or the maximum message signaling intensity, over the interface acceptable or allowed by the first network node. The first network node may specify in the request message to obtain from the second network node one or more parameters indicating characteristics of signaling messages of the second network node, e.g. any one or more of the maximum size for a message that can be sent from or received by the second network node, the maximum message sending or receiving rate over the interface acceptable or allowed by the second network node. If the interface setup procedure is successful, the second network node accepts the interface setup request and then for all the subsequent messages exchanged over the interface, both network nodes have to make sure that the messages to be sent adhere to the interface contract previously agreed between the two nodes in terms of messages size and frequency.

The first network node receives a response from the second network node. The response comprises one or more parameters indicating any one of: acceptance of the characteristics of signaling messages of the first network node, a cause for failure of receiving the interface setup request message, characteristics of signaling messages of the second network node.

The first network node sends a first message to the second network node. The first message comprises information on message fragmentation of an original message or information on list fragmentation of a list type IE contained in the original message to be sent to the second network node. The information on message fragmentation may comprise any one or more of the following: a list describing fragmentation of the original message; a list describing fragmentation of the information elements (lEs) of list type in the original message; a list of partial copies of the original message; a partial copy of the original message.

According to one aspect of the embodiments herein, the object is achieved by a second network node and method therein for handling message signaling to a first network node in a wireless communication network.

The second network node receives a first request message, i.e. an interface setup request message, from the first network node. The first request message comprises one or more parameters indicating characteristics of signaling messages of the first network node.

The second network node sends a response to the first network node. The response comprises one or more parameters indicating any one of: acceptance of one or more of the characteristics of signaling messages of the first network node, a cause for failure of receiving the interface setup request message, characteristics of signaling messages of the second network node.

The second network node receives a first message from the first network node. The first message comprises information on message fragmentation of an original message or information on list fragmentation of a list type Information Element contained in the original message to be sent to the second network node.

In one embodiment, in case the interface setup procedure fails, the second network node may include in a failure message sent in response to the interface setup message, the maximum size for a message that can be sent or received over the interface by the second network node, and/or the maximum message sending or receiving rate, or the maximum message sending or receiving frequency, or the maximum message signaling intensity, over the interface acceptable or allowed by the second network node. This information may be complemented by a cause for failure, which may point out at the fact that the failure at the second network node is due to a too large interface setup message.

In case that the overall interface message to be sent is too large, and in one embodiment, the sending network node may split the message into several fragments, including in each fragment the assistance information for the receiving network node to rebuild the entire message from the different fragments. In one example, such assistance information may consist of a fragment index, the total number of fragments and a message identifier, where the receiving network node will be able to know that a received fragment is part of the message identified by the message index and that the fragment is the nth fragment of a split message, where n may correspond to the fragment index.

On the other side, if the sending network node needs to send several messages at the rate that exceeds the agreed messages sending frequency or rate for the interface, the sending network node can aggregate several messages in a single message while respecting the maximum message size for the interface. The sending network node will include the assistance information for the receiving network node to be able to extract individual messages from the aggregated message. In one example, the sending network node may include in the aggregated message Message Identifiers corresponding to all the messages that have been aggregated together.

In case the interface setup procedure fails, or the second network node does not support it, or the second network node does not return to the first network node its own maximum message size and/or its own maximum signaling intensity, the first network node is not certain that all the messages sent by the second network adhere to the maximum size and/or maximum signaling intensity the first network node can accept.

In this case, as well as in one variant related to the case of successful interface setup procedure, the first network node and/or the second network node can indicate in one message sent to the other node whether the message is fragmented or not.

In another variant, which can be combined with the previous one, the first network node and/or the second network node can indicate in one message sent to the other node whether an expected subsequent message can be subject to delay (aiming to reduce the signaling rate over the air interface), or the requested periodicity for updates cannot be fulfilled due to exceeding the signaling rate.

In another embodiment, the fragmentation of the message occurs by means of fragmenting well defined parts of the message, for example by fragmenting specific information elements. One example of such fragmentation approach is to fragment lists. According to this embodiment the message may be defined and encoded to include the entirety of its information. However, for some of the information forming the message only a subset of data are signaled in the first message. The remaining data for the fragmented information is signaled via one or more additional messages. Embodiments herein provide some advantages:

Enabling a first network node to specify the maximum message size and the maximum messages rate in an interface setup request message sent to a second network node or in an interface setup failure message.

Enabling a sending network node to split a message or specific information element within the message in several fragments if the size of the initial message exceeds the maximum allowed size for the sending and/or for the receiving network node. At the receiving network node, embodiments herein enable the receiving network node to reconstruct the initial massage or the overall data constituting the fragmented information of the initial message from the different received fragments.

Enabling a sending network node to aggregate several messages in a single message in case when sending the messages individually will result in a message sending rate that exceeds the maximum allowed value for the interface. At the receiving network node, embodiments herein enable the receiving network node to extract individual messages from the received aggregated message.

Embodiments herein enable two peer network nodes to agree on the characteristics of the signaling messages, e.g. maximum message size and/or maximum messages rate, to be exchanged over an interface between the two network nodes before setting up the interface. Agreeing on a “signaling contract” for an interface between two network nodes ensures that all the messages sent over that interface are compliant to the “signaling contract” so there is no risk for the receiving network node to enter in a signaling processing collapse state due to an unappropriated ration between the signaling intensity and the signaling processing capacity at the receiving network node. Embodiments herein also enable a sending network node to adapt the size and the rate of the signaling message it sends over an interface to the “signaling contract” pre-established for that interface by splitting too large messages into several smaller fragments and/or by aggregating several small and too frequent messages info a less frequent series of larger messages.

Therefore embodiments herein provide improved methods and apparatus for handling message signaling between two network nodes in wireless communication networks. BRIEF DESCRIPTION OF THE DRAWINGS

Examples of embodiments herein are described in more detail with reference to attached drawings in which:

Figure 1 is a schematic block diagram illustrating NG RAN architecture;

Figure 2 is a schematic block diagram illustrating architecture for separation of gNB-

CU-CP and gNB-CU-UP;

Figure 3 is a schematic block diagram illustrating functional framework for RAN Intelligence;

Figure 4 is a schematic flow chart illustrating model training and model inference at NG-RAN for network energy saving;

Figure 5 is a schematic flow chart illustrating model training and model inference at NG-RAN for network load balancing;

Figure 6 is a schematic flow chart illustrating model training and model inference both located in RAN node;

Figure 7 is a schematic flow chart illustrating an example of signaling diagram for execution of AI/ML processes in NG-RAN, in case of model training at NG- RAN;

Figure 8 is a schematic block diagram illustrating a wireless communication network;

Figure 9 is a signal flow chart illustrating an example signaling flow between a first and second network nodes for interface setup according to embodiments herein;

Figure 10 is a signal flow chart illustrating an example signaling flow between a first and second network nodes for handling message fragmentation according to a first embodiment herein;

Figure 11 is a signal flow chart illustrating an example signaling flow between a first and second network nodes for handling message fragmentation according to a second embodiment herein;

Figure 12 is a signal flow chart illustrating an example signaling flow between a first and second network nodes for handling message fragmentation according to a third embodiment herein;

Figure 13 is a signal flow chart illustrating an example signaling flow between a first and second network nodes for handling message fragmentation according to a fourth embodiment herein; Figure 14 is a signal flow chart illustrating an example signaling flow between a first and second network nodes for handling message aggregation according to embodiments herein;

Figure 15 is a flow chart illustrating an example embodiment of a method performed in a first network node according to embodiments herein;

Figure 16 is a flow chart illustrating an example embodiment of a method performed in a second network node according to embodiments herein;

Figure 17 is a schematic block diagram illustrating an example embodiment of a network node.

DETAILED DESCRIPTION

Embodiments herein relate to communication networks in general. Figure 8 is a schematic overview depicting a communication network 800. The communication network 800 may be a wireless communication network comprising one or more RANs, and one or more CNs. The communication network 800 may use a number of different RATs, such as Wi-Fi, Long Term Evolution (LTE), LTE-Advanced, NR, Wideband Code Division Multiple Access (WCDMA), Global System for Mobile communications/enhanced Data rate for GSM Evolution (GSM/EDGE), Worldwide Interoperability for Microwave Access (WiMax), or Ultra Mobile Broadband (UMB), NR etc. just to mention a few possible implementations.

In the wireless communication network 800, one or more wireless communication devices 830, 831 , such as a UE, a mobile station or a wireless terminal, communicates via one or more Radio Access Networks (RAN) to one or more CNs. It should be understood by the skilled in the art that “wireless communication device” is a non-limiting term which means any terminal, wireless communication terminal, user equipment, Machine Type Communication (MTC) device, Device to Device (D2D) terminal, or node e.g. smart phone, laptop, mobile phone, sensor, relay, mobile tablets or even a small base station communicating within a cell.

Network nodes operate in the wireless communication network 800 such as a first network node 811, a second network node 812. The first and second network nodes 811 , 812 may be any of RAN node, such as gNB, eNB, en-gNB, ng-eNB, gNB etc. The first network node 811 provides radio coverage over a geographical area, a service area 11 , which may also be referred to as a beam or a beam group where the group of beams is covering the service area of a first radio access technology (RAT), such as 5G, LTE, Wi-Fi or similar. The second network node 812 provides radio coverage over a geographical area, a service area 12, which may also be referred to as a beam or a beam group where the group of beams is covering the service area of a second RAT, such as 5G, LTE, Wi-Fi or similar. It should be noted that a network node may be a RAN node, a CN node or an OAM node.

The first/second network nodes 811/812 may be a transmission and reception point e.g. a radio access network node such as a Wireless Local Area Network (WLAN) access point or an Access Point Station (AP STA), an access controller, a base station, e.g. a radio base station such as a NodeB, a gNB, an evolved Node B (eNB, eNode B), a base transceiver station, a radio remote unit, an Access Point Base Station, a base station router, a transmission arrangement of a radio base station, a stand-alone access point or any other network unit capable of communicating with a wireless communication device within the service area served by the respective first/second network nodes 811/812 depending e.g. on the radio access technology and terminology used. The first and the second network nodes 811/812 may be referred to as a source and a target network node, respectively, and may communicate with the wireless communication device 830, 831 with Downlink (DL) transmissions to the wireless communication device 830, 831 and Uplink (UL) transmissions from the wireless communication device 830, 831.

In the following, the terms “communication device”, “wireless terminal” and “UE” are used interchangeably. The term “network node”, “gNB”, “eNB”, “gNodeB” are used interchangeably.

A network node may be a RAN node, a gNB, an eNB, an en-gNB, a ng-eNB, a gNB-CU, a gNB-CU-CP, a gNB-CU-UP, an eNB-CU, an eNB-CU-CP, an eNB-CU-UP, an lAB-node, an lAB-donor DU, an lAB-donor-CU, an IAB-DU, an IAB-MT, an O-CU, an O- CU-CP, an O-CU-UP, an O-DU, an O-RU, an O-eNB, a Non-Real Time RAN Intelligent Controller (Non-RT RIC), a Real-Time RAN Intelligent Controller (RT-RIC), an OAM node, a Core Network node/function, a Cloud-based network function, a Cloud-based centralized training node etc.

The disclosure concerns the RAN application protocols (AP), e.g., XnAP, F1AP, E1AP, NGAP, etc. The domain of AI/ML is used through this document to describe the embodiments but the embodiments are not restricted to the AI/ML domain.

Embodiments for interfaces setup Figure 9 shows an example signal flow chart for an interface setup procedure between two network nodes 811 and 822. The interface setup procedure comprises the following steps or actions.

901. The first network node 811 sends a first request message, e.g. an interface setup request message, to the second network node 812. The first request message comprises one or more parameters indicating characteristics of signaling messages of the first network node. The characteristics of signaling messages of the first network node 811 comprises the following options.

In one embodiment, the first network node 811 indicates to the second network node 812 its own parameters related to maximum size of Application Protocol (AP) messages and/or maximum signaling intensity during the setup phase of the signaling interface towards the second network node 812. The maximum size can be unique for any Application Protocol message. Additionally or alternatively, the first network node 811 may indicate a maximum Information Element (IE) size. Such maximum size may apply to some or all of the IE types that can be exchanged in the AP's messages. The maximum size may be specific for a specific one or more type of lEs, for example the maximum IE size may be specific for lists contained in any Application Protocol message. The maximum size of AP messages and/or lEs can be different for outgoing Application Protocol messages as compared to incoming Application Protocol messages.

Alternatively or in addition to the maximum size information described above, one or more information described below may be provided by the first network node 811:

- In one option, which can be combined with other options described in this disclosure, the first network node 811 may indicate a maximum number of fragments in which an Application Protocol message and/or an Information Element of a specific type can be split into. As an example, the IE may be identified as a list or a sequence.

- In one option, which can be combined with other options described in this disclosure, the first network node 811 may indicate one or more of the following conditions:

. whether it is capable of fragmenting an Application Protocol message,

. whether it is capable of fragmenting an Information Element of a specific type, for example a list/sequence,

. whether fragmentation of messages received at the network node shall be used only when maximum signal size is reached or if it can be used regardless of that e.g., when the size of the Application Protocol message, or the size of one of the Information Elements exceeds a certain size. . whether fragmentation of messages signaled by the network node is used only when maximum signal size is reached or if it is used regardless of that e.g., when the size of the Application Protocol message, or the size of one of the Information Elements exceeds a certain size.

One case may be that it is known at the sending network node that a message that is smaller compared to the maximum tolerable size can be better or optimal at the receiving network node in terms of required computations or processing delay.

902. The second network node 812 sends a response, e.g. an interface setup response to the first network node 811. The response may comprise one or more parameters indicating any one of acceptance of the characteristics of signaling messages of the first network node, a cause for failure of receiving the interface setup request message, e.g. the interface setup request message is too large, characteristics of signaling messages of the second network node etc.

The second network node 812, when responding to the first network node 811 , can indicate whether the maximum size, in any of the variants described in this disclosure, as indicated by the first network node 811 is acceptable or not. Also, the second network node 812 may indicate in the response message its own parameters related to maximum size and/or maximum signaling intensity, where such parameters mirror the information described above.

In one embodiment, in case the characteristics of signaling messages of the first network node are not acceptable, the second network node 812 may include in the response message sent in response to the interface setup request, the maximum size for a message that can be sent or received over the interface by the second network node 812, and/or the maximum message sending or receiving rate, or the maximum message sending or receiving frequency, or the maximum message signaling intensity, over the interface acceptable or allowed by the second network node 812.

The second network node 812 may send a failure message to the first network node 811 in response to the interface setup request. The failure message may comprise a cause for failure, which may point out at the fact that the failure at the second network node 812 is due to a too large interface setup message.

Embodiments for Application Protocol messages fragmentation

The embodiments following in the subsequent subsections refer to the scenario in which two network nodes have run through the process of setting up a signaling interface between them and, following the interface setup process, each network node knows the capability of the other network node in terms of maximum acceptable signaling message size. It should be pointed out that the interface setup messages may also be subject to fragmentation at message or IE level. In that case, the messages may contain information concerning the maximum message or IE size the sending network node supports, as per above descriptions, but at the same time it may contain information that enables the receiving network node to understand how the message and/or lEs therein have been fragmented.

Message fragmentation variant one - Lists fragmentation in existing messages

Figure 10 shows a signaling flow chart between the first and second network nodes 811 , 812 according to an example embodiments herein for signaling information on message fragmentation and lists fragmentation in existing messages. The signaling flow chart comprises the following steps or actions.

1001 : The first network node 811 sends an ALPHA REQUEST message or a first message, e.g. an NG-RAN NODE CONFIGURATION UPDATE XnAP message, to the second network node 812. The first message comprises information on message fragmentation, e.g. a list describing fragmentation of the original message, a list of partial copies of the original message, a list describing fragmentation of the lEs of list type in the original message, a partial copy of the original message.

In this embodiment, the first network 811 sends an application protocol message to a second network node 812 but the message to be sent is larger than the maximum message size that the second network node 812 can handle and/or the message contains an IE that is larger than the allowed maximum IE size at the receiving network node. In this embodiment, the IE type on which a maximum size is imposed is list lEs. And the assumption is that the message sent by the first network node 812 contains one or more information elements encoded as list of items.

To cope with the maximum message or IE size at the second network node 812, the first network node 811 will split the message to be transferred, i.e. the “original message”, in several partial copies of the message. Namely, the message structure will be represented in full in each message fragment. That means that all the lEs forming the message will be expressed in every fragment of the message. However, the content of the one or more fragmented lists will be split across the different fragments. As an example, if the message contains a list with overall 100 items, and if the message is made of 10 fragments, the first fragment will contain list items 1 to 10, the second fragment will contain list items 11 to 20 and so on. Therefore, instead of carrying the entire list from the original message each partial copy of the original message contains a fragment of one or more of the lists of the original message. The size of each partial copy of the message, i.e. fragment, is less than the maximum message size accepted by the second network node 812, if a message size limit applies. The size of each sub set of list items contained in a partial copy of the message, i.e. fragment, is less than the maximum list size accepted by the second network node 812, if an IE size limit applies.

The following information may be included either in the first partial copy of the original message, i.e. first fragment, or in every partial copy:

• the name of the one or more lists being fragmented;

• a unique identifier for each list fragmentation process;

• the number of fragments in which the list will be fragmented;

• for each fragmented list, the frame number of the current list fragment, if a list fragment is contained in the message;

• for each fragmented list, the size of the current list fragment, if a list fragment is contained in the message;

• the maximum size the sending network node can receive for lEs of list type, if not already provided;

• The overall size of the list, when taking all fragments into account;

In a subvariant of the current variant the list fragment could contain only the following elements:

• the name of the list being fragmented;

• a unique identifier for the list fragmentation process;

• the current number of the fragment;

• the length of the fragment.

If the receiving network node, i.e., the second network node 812 cannot interpret the information contained in the list describing the fragmentation of the original message, it should ignore the information describing the fragmentation and it should consider each sub-set of the list items received not as a fragment of the original message but as a standalone message, where the list contained includes information that the receiving network node should take into consideration in addition to the information previously received for the same list. 1002-1004: The first network node 811 continues sends messages comprises information on message fragmentation to the second network node 812 until all fragments of the original message are sent.

1005: The second network node 812 sends a response to the network node 811.

If the original message send by the first network node 811 to the second network node 812 requires an acknowledgment to be sent from the second network node 812 to the first network node 811 , the second network node 812 should first wait to receive all the fragments for all the list, as indicated in the first partial copy of the original message, before sending the acknowledgement.

If the second network node 812 does not receive all the expected list fragments within a certain time it should send a failure message instead of an acknowledgment to the first network node 811. The failure message could contain an appropriate failure cause and indicate the list of missing list fragments with their corresponding lists.

In another embodiment, if the second network node 812 does not receive all the list fragments, it may send to the first network node 811 a second message where the missing fragments are indicated. This enables the first network node 811 to retransmit the messages containing the list fragment missing.

In another embodiment, each message signaled by the first network node 811 and containing a list fragment is subject to acknowledgement by the second network node 812. If the first network node 811 does not receive an acknowledgement for a given fragment message, the first network node 8111 may re-transmit the message containing the missing fragment, until the message is acknowledged by the second network node 812.

As an example of this embodiment let’s consider the NG-RAN NODE CONFIGURATION UPDATE XnAP message presented in Table 1.

Table 1

A partial copy of this initial message carrying fragments of the lists in the initial message is presented in the Table 2, showing first and/or “Nth”partial copy of NG-RAN NODE CONFIGURATION UPDATE XnAP message, where the additional lEs are

5 indicated by underlined text.

Table 2

Message fragmentation variant two -New message for lists fragments transfer Figure 11 shows a signaling flow chart between two network nodes according to an example embodiments herein for signaling information on message fragmentation and

5 lists fragments transfer. The signaling flow chart comprises the following steps or actions. 1101 : The first network node 811 sends to the second network node 812 a first message, e.g. an alpha request message, comprising information on message fragmentation.

In one embodiment, the first message containing the list message may include the 10 information described above for the first partial copy of the original message or first fragment.

1102: The first network node 811 sends to the second network node 812 a second message comprising fragments of the fragmented lists.

In this embodiment the first message is followed by new messages that contain only 15 the fragments of the fragmented lists.

In one example, the first message may resemble the message structure in Table 2, while the following messages may be represented as follows:

The lEs indicated in the message structure above, and in all other message structures where they are introduced, are defined as follows:

List Name: This is the name of the list that is fragmented. It corresponds to the

5 name of the IE corresponding to the fragmented list. For example, if the list fragmented is the Xn List of Served Cells NR, the List name will be “List of Served Cells NR”.

Maximum List Size: This IE is present if not indicated before and it represents the maximum size the sending network node allows for reception of the list identified by the List Name.

10 Fragmentation ID: This is an identifier that identifies the fragmentation process over the interface. Each fragmentation ID is unique over the interface.

Number of Fragments: it indicates the total number of fragments the list is fragmented into.

Fragment number: it indicates the fragment number carried by the current message. Fragment length: it indicates the length in bytes of the currently carried fragment.

1105: The second network node 812 sends a response to the first network node

811.

The response message should be a successful response if the second network node has received all the fragments of the original message.

In case the second network node hasn’t received all the fragments within a certain time interval the second network node should send a failure response indicating missing fragments.

In another embodiment, each message signaled by the first network node 811 and containing a list fragment is subject to acknowledgement by the second network node

812. If the first network node 811 does not receive an acknowledgement for a given fragment message, the first network node 8111 may re-transmit the message containing the missing fragment, until the message is acknowledged by the second network node 812.

Message fragmentation variant three - New message for messages fragments transfer

Figure 12 shows a signaling flow chart between the first and second network nodes 811 , 812 according to an example embodiments herein for signaling information on message fragmentation and messages fragments transfer. The signaling between the first and second network nodes 811, 812 comprises the following steps or actions.

1201-1204: The first network node 811 sends one or more encapsulating messages to the second network node 812. Each encapsulating message comprises at least one fragment of a large message.

In one embodiment, the handling of messages exceeding a certain maximum size (large messages) is realized as follows:

- a new encapsulating message may be introduced e.g. an XN TRANSFER XnAP message, which encapsulates at least one fragment of a large message, in the most typical case the new message comprises only one fragment of a large message, but other cases are not precluded, for instance the new message can comprise a first fragment of a first large message and a second fragment of a second large message, provided that the size of the resulting message does not exceed the maximum size.

- a plurality of instances of the new encapsulating message may be sent from the first network node to the second network node or vice versa.

- the receiving node, i.e. the second network node 812 upon reception of a certain encapsulating message, determines that the first/second/Nth, last segment of a certain large message has been received.

- the receiving node determines that all fragments of a certain large message have been received and reassembles the fragments into the original large message.

- in case of missing reception of a fragment the mechanisms described above for fragment acknowledgement and retransmission apply.

The encapsulating message comprises one or more of:

- an identifier of the message for which a fragment is being transferred within the encapsulating message e.g., the message identifier of the XN SETUP REQUEST message.

- the identifier/number of the fragment being transferred within the encapsulating message, e.g., the first fragment, the second fragment,... the Nth fragment, the second- to-last fragment, the last fragment.

- the number of fragments in which the large message has been fragmented.

- an indication, e.g., a bit or a flag, indicating whether the fragment being transferred in the encapsulating message is the first fragment or the last fragment.

- whether a subsequent fragment for the same large message referenced by the identifier can be expected. 1205: The second network node 812 sends a response to the first network node

811.

Message fragmentation variant four - Multiple list fragmentation in data reporting messages

Figure 13 shows a signaling flow chart between the first and second network nodes 811 , 812 according to an example embodiments herein for signaling information on message fragmentation and multiple list fragmentation in data reporting messages. The signaling between the first and second network nodes 811 , 812 comprises the following steps or actions.

1301 : The first network node 811 sends a measurement request, e.g. an AI/ML measurements request, to the second network node 812. In this embodiment the first network node 811 is a network node running an AI/ML model. For the purposes of training and/or assessing the performance of the model, the first network node 811 requires measurements reports from the second network node 812 by sending a FIRST_MESSAGE to the second network node 812.

1302: The second network node 812 sends a response to the first network node 811.

The measurements requested by the first network node 811 may contain one or more list of measurements elements. For example one list of measurements may comprise the values of throughput for UEs handed over from the first network node 811 to the second network node 812 while a second list of measurement may comprise the throughput for the UEs already served by the second network node 812 at the moment when a handover of a UE from the first network node 811 to the second network node 812 occurs.

For each list of measurements requested by the first network node 811 from the second network node 812, the first network node 811 may specify:

• if list fragmentation is allowed or not;

• the maximum number of fragments a list may be fragmented into;

• the maximum number of items a list may contain;

• the maximum number of items a fragment of the list may contain.

1303: The second network node 812 sends a measurements report message to the first network node 811.

After accepting the measurements reporting request and when the measurements reporting condition are met, the second neatwork node 812 will send a measurements report message back to the first network node 811.

If the size of the reporting message exceeds the maximum message size the first network node 811 can handle and if list fragmentation is allowed for one or more of the measurements lists comprised in the measurements report message, the second network node 812 should fragment the measurements report message before sending it to the first network node 811.

For the fragmentation of the measurements report message, the second network node 812 may use any of the solutions described in previous section Message fragmentation variant one.

1304: The second network node 811 continues sends measurements report messages to the first network node 811 according to the requested measurements from the first network node 811. Embodiments for Application Protocol messages aggregation

Figure 14 shows a signaling flow chart between the first and second network nodes 811 , 812 according to an example embodiments herein for messages aggregation. The signaling between the first and second network nodes 811 , 812 comprises the following steps or actions.

1401 : The first network node 811 sends a first measurement request, e.g. an AI/ML measurements request A, to the second network node 812.

1402: The second network node 812 sends a response to the first network node 811 in response to the first measurement request, e.g. an AI/ML measurements response A.

1403: The first network node 811 sends a second measurement request, e.g. an AI/ML measurements request B, to the second network node 812.

1404: The second network node 812 sends a response to the first network node 811 in response to the second measurement request, e.g. an AI/ML measurements response B.

1405: The second network node 812 sends a measurement report message to the first network node 811. The measurement report message comprises an aggregate message of reporting messages in response to the first and second requested measurements.

The messages aggregation embodiments are used by the reporting node, i.e. the second network node 811 to aggregate multiple messages or multiple datasets to lower the signaling intensity i.e. the number of AP messages per second, while respecting the maximum message size signaled by the requesting node during the negotiation process.

In one embodiment, the second network node 812 aggregates multiple Application Protocol messages (AP) in a single AP message, the resulting message size being lower that the maximum size advertised by the first network node 811 during the negotiation process (see previous embodiments). The aggregated message may be composed of a list of AP messages to be aggregated, each item of the list comprising:

- A message type or a message identifier, e.g. Procedure Code and Type of Message.

- A bitstring containing one AP message.

A non-limiting example of a possible implementation in TS 38.423 is given below:

AGGREGATED MESSAGES CONTAINER This message is sent by NG-RAN node 2 to NG-RAN nodel and aggregates multiple XnAP messages sent by NG-RAN node 2 to NG-RAN nodel .

Direction: NG-RAN node 2 -> NG-RAN nodel .

Aggregation of multiple datasets in one reporting message

The following embodiments are applicable to network nodes exchanging multiple datasets for the purpose of e.g. AI/ML operations, SON operations.

In one embodiment, the second network node 812 aggregates multiple datasets belonging to different requests into a single message, this message being composed of one or more of the following information:

- A list of request identifiers, uniquely identifying the requests.

- A list of datasets, pertaining to the request identifiers.

RESOURCE STATUS UPDATE AGGREGATED

This message is sent by NG-RAN node 2 to NG-RAN node 1 to report the results of the multiple measurements IDs.

Direction: NG-RAN node 2 -> NG-RAN node 1.

Other embodiments related to signaling intensity In one embodiment, a first network node 811 is sending or receiving periodic messages, e.g., resource update messages, to a second network node 812, and while doing that, it determines that the sending or receiving signaling intensity caused at least in part by the sending or receiving of the above periodic messages exceeds a certain first threshold. In this case the first network node 811 can notify the second network node 812 one or more of the following:

- continue sending the periodic messages according to the requested periodicity is no longer possible.

- the sending of the periodic messages according to the requested periodicity is paused. - the maximum tolerable signaling intensity rate is exceeded.

- maintain the current periodic update, with a reduced (larger) reporting periodicity.

When the signaling intensity decreases below a second threshold which may be different than the first threshold, the first network node 811 can notify the second network node 812 that normal operation can be restored, i.e. , the first network node 811 can send to the second network node one or more of the following:

- sending the periodic messages according to the requested periodicity is (again) possible.

- the sending of the periodic messages according to the requested periodicity is resumed.

- maintain the current periodic update, according to an original (smaller) reporting periodicity.

The first network node 811 can detect that the signaling intensity exceeds a certain threshold value while sending or receiving fragmented messages. In this case, the first network node 811 can send to the second network node 812 indications that:

- the sending/receiving of the large (fragmented) message can continue until all the fragments are sent/received, or

- the sending/receiving of the large (fragmented) message fails, or

- the sending/receiving of the large (fragmented) message is paused.

Other embodiments related to signaling between nodes of different radio access technologies

The methods described in the preceding embodiments can be extended to the case of application protocol messages or parts of an application protocol message to be sent from a first network node 811 pertaining to a first radio access technology e.g., E-UTRAN, to a second network node 812 pertaining to a second radio access technology e.g., NR.

In a non-limiting example, an NG-RAN node may want to send a signaling message to an E-UTRAN node, via one or more Core Network nodes e.g., one AMF node and an MME node. According to the methods described herein, the NG-RAN node, before sending the message can discover the maximum size possible for a signaling message to reach the E-UTRAN node, or a maximum signaling intensity towards the E-UTRAN node, and if the intended message is exceeding the limit, sends fragmented messages instead. To discover the maximum message size and/or the maximum signaling intensity, the NG- RAN node can send an NGAP message towards the AMF, comprising a request for the E- UTRAN node to return the maximum message size or the maximum signaling intensity allowed by the E-UTRAN node. In the main case, the content of the NGAP message is transparently conveyed from the AMF via the MME to the E-UTRAN node, and the E- UTRAN node can respond to the NR node with the maximum size possible and/or the maximum signaling intensity using an S1AP message whose content is passed to the NG- RAN node via the CN nodes. The reverse is also possible, e.g., the E-UTRAN node can initiate an S1AP procedure towards the MME, sending a message containing a request for the NR node to provide the maximum message size for the NR node, and the NR node may respond with the maximum size at its end.

According to embodiments described above, a method performed by a first network node 811 for handling message signaling to a second network node 812 in the wireless communication network 800 will be described with reference to Figure 15. The method comprises the following actions which may be performed in any suitable order.

Action 1501

In order for the first and second network nodes 811, 812 to understand each other’s characteristics of signaling messages and achieve an agreement on the characteristics of the signaling messages, e.g. maximum message size and/or maximum messages rate, an interface setup procedure between two network nodes is initiated.

The first network node 811 sends an interface setup request message to the second network node 812. The interface setup request message comprises one or more parameters indicating characteristics of signaling messages of the first network node 811.

The interface setup request message may further comprise a request to obtain from the second network node 812 one or more parameters indicating characteristics of signaling messages of the second network node 812.

Action 1502

The first network node 811 receives a response from the second network node 812. The response comprises one or more parameters indicating any one of: acceptance of the characteristics of signaling messages of the first network node, a cause for failure of receiving the interface setup request message, characteristics of signaling messages of the second network node.

The characteristics of signaling messages of the first/second network nodes 811/812 may comprise one or more of the following: a) a maximum size of a message can be sent or received by the first/second network nodes 811/812; b) a maximum Information Element (IE) size of a specific type can be sent or received by the first/second network nodes 811/812; c) a maximum signaling intensity acceptable or allowed by the first/second network nodes 811/812; d) a maximum sending or receiving rate acceptable or allowed by the first/second network nodes 811/812; e) a maximum message sending or receiving frequency acceptable or allowed by the first/second network nodes 811/812; f) a maximum number of fragments the first/second network node 811 , 812 is able to receive for a split message; g) a maximum number of fragments the first/second network node 811 , 812 is able to receive for a split IE of a specific type.

The interface setup request message may further indicate one or more of the following: a maximum number of fragments in which a message can be split into; a maximum number of fragments in which a specific type IE can be split into; a capability of fragmenting a message; a capability of fragmenting a specific type IE; whether fragmentation of messages is used only when the size of a message exceeding a maximum message size or the size of an IE exceeding a certain size; whether fragmentation of messages is used regardless of the size of a messages exceeding a maximum message size or the size of an IE exceeding a certain size; whether and how the interface setup request message is fragmented.

If the interface setup procedure described above is successful, the second network node 812 accepts the interface setup request and then for all the subsequent messages exchanged over the interface, both network nodes 811 , 812 have to make sure that the messages to be sent adhere to the interface contract previously agreed between the two network nodes 811 , 812 in terms of messages size and frequency. The method may comprise the following actions for handling message signaling between the two network nodes 811 , 812.

Action 1503

The first network node 811 sends a first message to the second network node 812. The first message comprises information on message fragmentation of an original message or information on list fragmentation of a list type IE contained in the original message to be sent to the second network node.

The first message may comprise any one or a combination of the following: a list describing fragmentation of the original message; a list describing fragmentation of the one or more list type lEs contained in the original message; a list of partial copies of the original message; a number of fragments of the original message or the list type IE contained in the original message being split; a length or size of each fragment; a partial copy or a fragment of the original message; a fragment of lists of the list type IE.

A partial copy or a fragment of the original message may comprise one or more of the following: the name of the one or more list type lEs being fragmented; a unique identifier for each fragment of lists; the number of fragments in which the original message or the list type IE contained in the original message is fragmented; for each fragmented list type IE, the frame number of the current fragment of lists, if a fragment of lists is contained in the first message; for each fragmented list type IE, the size of the current fragment of lists, if a fragment of lists is contained in the first message; the maximum size the first network node 811 can receive for list type lEs, if not already provided; the overall size of the list type IE, when taking all fragments into account.

Each fragment of lists may comprise one or more following elements: a name of the list type IE being fragmented; a unique identifier for the fragment of lists; a current number of the fragment of lists; a length or size of the fragment of lists.

Action 1504

The first network node 811 sends to the second network node 812 a second message comprising a fragment of the original message or a fragment of lists of the list type IE contained in the original message.

The second message may comprise one or more of the following lEs: List Name,

Maximum List Size,

Fragmentation ID,

Number of Fragments,

Fragment number,

Fragment length.

For exchanging measurements requesting and reporting, the method may further comprise the following actions which may be performed in any suitable order.

Action 1505

The first network node 811 sends a measurement request to the second network node 812. The measurement request comprises a list of measurements requested by the first network node 811 .

Each list of measurements requested by the first network node 811 may comprise one or more of the following information: if list fragmentation is allowed or not; a maximum number of fragments a list may be fragmented into; a maximum number of items a list may contain; a maximum number of items a fragment of the list may contain.

Action 1506

The first network node 811 receives a measurements response message from the second network node 822. The measurements response message comprises information on message fragmentation.

Action 1506a

The first network node 811 receives one or more measurements report messages from the second network node 812. Each measurements report message comprises a fragment of the lists of measurements.

For aggregation of multiple datasets in one reporting message, the method may further comprise the following actions which may be performed in any suitable order

Action 1507

The first network node 811 sends a first measurement request to the second network node 812.

Action 1508 The first network node 811 receives a response from the second network node 812 in response to the first measurement request.

Action 1509

The first network node 811 sends a second measurement request to the second network node 812.

Action 1510

The first network node 811 receives a response from the second network node 812 in response to the second measurement request.

Action 1511

The first network node 811 receives a measurement report message from the second network node 812. The measurement report message comprises an aggregate message of reporting messages in response to the first and second requested measurements.

The aggregated message may comprise a list of messages been aggregated, and each item of the list may comprise: a message type or a message identifier; a bitstring containing one message.

The aggregate message may comprise multiple datasets belonging to different measurements requests, and may comprise one or more of the following information:

A list of request identifiers, uniquely identifying the different measurements requests;

A list of datasets, pertaining to the request identifiers.

When the first network node 811 is sending or receiving periodic messages according to a first requested reporting periodicity, the method may further comprises the following actions.

Action 1512

When it is determined that the sending or receiving signaling intensity caused at least in part by the sending or receiving of the periodic messages exceeds a first threshold, the first network node 811 sends a first notification to the second network node 812 to notify one or more of the following: continue sending the periodic messages according to the first requested reporting periodicity is no longer possible, sending of the periodic messages according to the first requested periodicity is paused, the maximum signaling intensity rate is exceeded, maintain the current periodic update, with a reduced second reporting periodicity compared to the first requested reporting periodicity.

When the first network node 811 is sending or receiving fragmented messages, and when it is determined that signaling intensity exceeds a first threshold, the first indication may indicate any one of: sending/receiving of the fragmented messages can continue until all the fragments are sent/received; sending/receiving of the fragmented message fails; sending/receiving of the fragmented message is paused.

Action 1513

When the signaling intensity decreases below a second threshold, the first network node 811 sends a second notification to the second network node 812 to notify one or more of the following: sending the periodic messages according to the first requested reporting periodicity is possible, sending of the periodic messages according to the first requested reporting periodicity is resumed, maintain the current periodic update, according to the first requested reporting periodicity or a smaller second reporting periodicity compared to the first requested reporting periodicity.

According to embodiments described above, a method performed by a second network node 812 for handling message signaling will be described with reference to Figure 16. The method comprises the following actions which may be performed in any suitable order.

Action 1601

The second network node 812 receives a first request message from the first network node 811. The first request message comprises one or more parameters indicating characteristics of signaling messages of the first network node 811.

Action 1602

The second network node 812 sends a response to the first network node 811. The response comprises one or more parameters indicating any one of: acceptance of one or more of the characteristics of signaling messages of the first network node 811 , a cause for failure of receiving the interface setup request message, characteristics of signaling messages of the second network node 812.

The cause for failure of receiving the interface setup request message may be due to a too large interface setup message.

The characteristics of signaling messages of the second network node 812 may comprise any one or more the following: a maximum message size that can be sent or received by the second network node 812, a maximum message sending or receiving rate or frequency acceptable or allowed by the second network node 812, a maximum message signaling intensity acceptable or allowed by the second network node 812.

Action 1603

The second network node 812 receives a first message from the first network node 811 . The first message comprises information on message fragmentation of an original message or information on list fragmentation of a list type Information Element contained in the original message to be sent to the second network node 812.

Action 1604

The second network node 812 receives a second message comprising a fragment of the original message or a fragment of lists of a list type IE contained in the original message.

The second network node 812 continually receive messages from the first network node 811 until all fragments of the original message or all fragments of lists of a list type IE have been received.

Action 1605

According to some embodiments herein, the second network node 812 may send a message to the first network node 811 indicating a missing fragment of the original message or missing fragment of lists.

If the second network node 812 does not receive all the expected fragments within a certain time it should send a failure message instead of an acknowledgment to the first network node 811. The failure message could contain an appropriate failure cause and indicate missing fragments. This enables the first network node 811 to retransmit the messages containing the missing fragments.

For exchanging measurements requesting and reporting between the first and second network nodes 811/812, the method may further comprise the following actions which may be performed in any suitable order.

Action 1606

The second network node 812 may receive a measurements request message from the first network node 811, wherein the measurements request message comprises one or more lists of measurements requested by the first network node 811.

Action 1607

The second network node 812 may sends a measurements response message to the first network node 811. The measurements response message comprises information on message fragmentation. If the size of the reporting message exceeds the maximum message size the first network node 811 can handle and if list fragmentation is allowed for one or more of the measurements lists comprised in the measurements report message, the second network node 812 should fragment the measurements report message before sending it to the first network node 811.

Action 1608

The second network node 812 may sends one or more measurements report messages to the first network node 811. Each measurements report message comprises a fragment of the lists of measurements.

For messages aggregation, the method may comprise the following actions.

Action 1610 The second network node 812 may receive a first measurements request message from the first network node 811.

Action 1611

The second network node 812 may send a response to the first network node 811 in response to the first measurements request message.

Action 1612

The second network node 812 may receive a second measurements request message from the first network node 811.

Action 1613

The second network node 812 may send a response to the first network node 811 in response to the second measurements request message.

Action 1614

The second network node 812 may send a measurements report message to the first network node 811. The measurements report message comprises an aggregated message of reporting messages in response to the first and second requested measurements.

The aggregated message may comprise a list of messages been aggregated, and each item of the list may comprise a message type or a message identifier, a bitstring containing one message.

The aggregated message may comprises multiple datasets belonging to different measurements requests, and may comprises a list of request identifiers identifying the different measurements requests, a list of datasets pertaining to the request identifiers.

To perform the methods in the first/second network nodes 811/812, the first/second network nodes 811/812 comprises modules as shown in Figure 17. The first/second network nodes 811/812 comprises a receiving module 1710, a transmitting module 1720, a determining module 1730, a processing module 1740, a memory 1750 etc.

The first network node 811 is configured to perform the method according to any one of the Actions 1501-1513 described above for handling message signaling to a second network node 812 in a wireless communication network 800.

For examples, the first network node 811 is configured to, by means of e.g. the transmitting model 1720 being configured to, send an interface setup request message to the second network node 812. The interface setup request message comprises one or more parameters indicating characteristics of signaling messages of the first network node 811. The first network node 811 is configured to, by means of e.g. the receiving model 1710 being configured to, receive a response from the second network node 812. The response comprises one or more parameters indicating any one of: acceptance of the characteristics of signaling messages of the first network node 811 , a cause for failure of receiving the interface setup request message, characteristics of signaling messages of the second network node 812.

The second network node 812 is configured to perform the method according to any one of the Actions 1601-1614 described above for handling message signaling to a first network node 811 in a wireless communication network 800.

For examples, the second network node 812 is configured to, by means of e.g. the receiving model 1710 being configured to, receive an interface setup request message from the first network node 811. The interface setup request message comprises one or more parameters indicating characteristics of signaling messages of the first network node 811.

The second network node 812 is configured to, by means of e.g. the transmitting model 1720 being configured to, send a response to the first network node 811. The response comprises one or more parameters indicating any one of: acceptance of one or more of the characteristics of signaling messages of the first network node 811 , a cause for failure of receiving the interface setup request message, characteristics of signaling messages of the second network node 812.

The second network node 812 is configured to, by means of e.g. the receiving model 1710 being configured to, receive a first message from the first network node 811. The first message comprises information on message fragmentation of an original message or information on list fragmentation of a list type Information Element contained in the original message.

The methods according to embodiments herein may be implemented through one or more processors, such as the processor 1760 in the first/second network nodes 811/812 together with computer program code for performing the functions and actions of the embodiments herein. The program code mentioned above may also be provided as a computer program product, for instance in the form of computer readable medium or a data carrier 1780 carrying computer program code 1770, as shown in Figure 17, for performing the embodiments herein when being loaded into the first/second network nodes 811/812. One such carrier may be in the form of a CD ROM disc. It is however feasible with other data carriers such as a memory stick. The computer program code may furthermore be provided as pure program code on a server or a cloud and downloaded to the first/second network nodes 811/812.

Some example embodiments are listed in the following:

Embodiment 1. A method performed in a first network node (811) for handling message signaling to a second network node (812) in a wireless communication network, the method comprising: sending (1501) an interface setup request message to the second network node (812), wherein the interface setup request message comprises one or more parameters indicating characteristics of signaling messages of the first network node; receiving (1502) a response from the second network node (812), wherein the response comprises one or more parameters indicating any one of: acceptance of the characteristics of signaling messages of the first network node, a cause for failure of receiving the interface setup request message, characteristics of signaling messages of the second network node.

Embodiment 2. The method according to Embodiment 1 , wherein the characteristics of signaling messages of the first and second network nodes comprises one or more of the following: a maximum size of a message, a maximum Information Element (IE) size, a maximum signaling intensity, a maximum number of fragments in which a message and/or an IE of a specific type can be split into, (IE may be identified as a list or a sequence), a maximum number of fragments the first network node 811 is able to receive for a message and/or an IE of a specific type being split, capability of fragmenting a message, capability of fragmenting an IE of a specific type, for example a list/sequence, whether fragmentation of messages received at the network node (811/812) shall be used only when the maximum size of a message is reached, or the size of one of the IE exceeds a certain size, or whether fragmentation of messages received at the network node (812) can be used regardless of the size of the message received at the network node exceeding the maximum size of a message, or the size of one of the IE exceeding a certain size, whether fragmentation of messages signaled by the network node (811/812) is used only when maximum signal size is reached or whether fragmentation of messages signaled by the network node (811/812) is used regardless of the size of the messages signaled by the network node exceeding the maximum size of the message, or the size of one of the IE exceeding a certain size;

Embodiment 3. The method according to any one of Embodiments 1-2, further comprising: sending (1503) a first message to the second network node, wherein the first message comprises information on message fragmentation of an original message to be sent to the second network node.

Embodiment 4. The method according to Embodiment 3, wherein the information on message fragmentation comprises any one or more of the following: a list describing fragmentation of the original message; a list describing fragmentation of the lEs of list type in the original message; a list of partial copies of the original message; a partial copy of the original message.

Embodiment 5. The method according to Embodiment 4, wherein a partial copy of the original message comprises one or more of the following: the name of the one or more lists being fragmented; a unique identifier for each list fragmentation process; the number of fragments in which the list is fragmented; for each fragmented list, the frame number of the current list fragment, if a list fragment is contained in the message; for each fragmented list, the size of the current list fragment, if a list fragment is contained in the message; the maximum size the sending network node can receive for lEs of list type, if not already provided; the overall size of the list, when taking all fragments into account. Embodiment 6. The method according to any one of Embodiments 4-5, wherein the list fragment comprises the following elements: the name of the list being fragmented; a unique identifier for the list fragmentation process; the current number of the fragment; the length or size of the fragment.

Embodiment 7. The method according to any one of Embodiments 1-6, further comprising: sending (1504) to the second network node (812) a second message comprising fragments of the fragmented lists.

Embodiment 8. The method according to Embodiment 6, wherein the second message comprises one or more of the following lEs:

List Name,

Maximum List Size,

Fragmentation ID,

Number of Fragments,

Fragment number,

Fragment length.

Embodiment 9. The method according to any one of Embodiments 1-8, wherein the first message is an NG-RAN NODE CONFIGURATION UPDATE XnAP message between the first and second network nodes.

Embodiment 10. The method according to any one of Embodiments 1-8, wherein the first message is a new encapsulating message introduced between the first and second network nodes, wherein the encapsulating message comprises at least one fragment of a large message.

Embodiment 11. The method according to any one of Embodiments 10, wherein a plurality of instances of the new encapsulating message is sent from the first network node to the second network node. Embodiment 12. The method according to any one of Embodiments 1-11, further comprising: sending (1505) a measurement request to the second network node, wherein the measurement request comprises a list of measurements requested by the first network node; receiving (1506) a measurements report message from the second network node, wherein the measurements report message comprises information on message fragmentation.

Embodiment 13. The method according to Embodiment 12, wherein each list of measurements requested by the first network node comprises one or more of the following information: if list fragmentation is allowed or not; a maximum number of fragments a list may be fragmented into; a maximum number of items a list may contain; a maximum number of items a fragment of the list may contain.

Embodiment 14. The method according to any one of Embodiments 1-11, further comprising: sending (1507) a first measurement request to the second network node, receiving (1508) a response from the second network node in response to the first measurement request; sending (1509) a second measurement request to the second network node, receiving (1510) a response from the second network node in response to the second measurement request; receiving (1511) a measurement report message from the second network node, wherein the measurement report message comprises an aggregate message of reporting messages in response to the first and second requested measurements.

Embodiment 15. The method according to Embodiment 14, wherein the aggregate message comprises multiple datasets belonging to different requests, and comprises one or more of the following information:

A list of request identifiers, uniquely identifying the requests.

A list of datasets, pertaining to the request identifiers. Embodiment 16. The method according to any one of Embodiments 1-15, wherein when the first network node (811) is sending or receiving periodic messages according to a first requested reporting periodicity, the method further comprising: when it is determined that the sending or receiving signaling intensity caused at least in part by the sending or receiving of the periodic messages exceeds a first threshold, sending (1512) a first notification to the second network node to notify one or more of the following: continue sending the periodic messages according to the first requested reporting periodicity is no longer possible, the sending of the periodic messages according to the first requested periodicity is paused, the maximum signaling intensity rate is exceeded, maintain the current periodic update, with a reduced second reporting periodicity compared to the first requested periodicity; when the signaling intensity decreases below a second threshold, sending (1513) a second notification to the second network node to notify one or more of the following: sending the periodic messages according to the first requested reporting periodicity is possible, sending of the periodic messages according to the first requested reporting periodicity is resumed, maintain the current periodic update, according to a first requested reporting periodicity or a smaller second reporting periodicity compared to the first requested periodicity.

Embodiment 17. The method according to any one of Embodiments 1-15, wherein the first and second network nodes belong to different radio access technologies.

Embodiment 18. A method performed in a second network node (812) for handling message signaling to a first network node (811) in a wireless communication network, the method comprising: receiving (1601) a first request message from the first network node (811), wherein the first request message comprises one or more parameters indicating characteristics of signaling messages of the first network node, sending (1602) a response to the first network node (811), wherein the response comprising one or more parameters indicating any one of: acceptance of one or more of the characteristics of signaling messages of the first network node, a cause for failure of receiving the interface setup request message, characteristics of signaling messages of the second network node; receiving (1603) a first message from the first network node, wherein the first message comprises information on message fragmentation of an original message to be sent to the second network node. Embodiment 19. The method according to Embodiment 18, wherein the characteristics of signaling messages of the second network node (812) comprises any one or more the following: a maximum message size that can be sent or received by the second network node (812), a maximum message sending or receiving rate or frequency acceptable or allowed by the second network node (812), a maximum message signaling intensity acceptable or allowed by the second network node (812).

Claims

1 . A method performed in a first network node (811) for handling message signaling to a second network node (812) in a wireless communication network (800), the method comprising: sending (901 , 1501) an interface setup request message to the second network node (812), wherein the interface setup request message comprises one or more parameters indicating characteristics of signaling messages of the first network node (811); receiving (902, 1502) a response from the second network node (812), wherein the response comprises one or more parameters indicating any one of: acceptance of the characteristics of signaling messages of the first network node (811), a cause for failure of receiving the interface setup request message, characteristics of signaling messages of the second network node (812).

2. The method according to claim 1 , wherein the interface setup request message further comprises a request to obtain from the second network node (812) one or more parameters indicating characteristics of signaling messages of the second network node (812).

3. The method according to any one of claims 1-2, wherein the characteristics of signaling messages of the first/second network nodes (811/812) comprise one or more of the following: a maximum size of a message can be sent or received by the first/second network nodes (811/812); a maximum Information Element (IE) size of a specific type can be sent or received by the first/second network nodes (811/812); a maximum signaling intensity acceptable or allowed by the first/second network nodes (811/812); a maximum sending or receiving rate acceptable or allowed by the first/second network nodes (811/812); a maximum message sending or receiving rate acceptable or allowed by the first/second network nodes (811/812); a maximum number of fragments the first/second network node (811 , 812) is able to receive for a split message; a maximum number of fragments the first/second network node (811 , 812) is able to receive for a split IE of a specific type.

4. The method according to any one of claims 1-3, wherein the interface setup request message may further indicate one or more of the following: a maximum number of fragments in which a message can be split into; a maximum number of fragments in which a specific type IE can be split into; a capability of fragmenting a message; a capability of fragmenting a specific type IE; whether fragmentation of messages is used only when the size of a message exceeding a maximum message size or the size of an IE exceeding a certain size; whether fragmentation of messages is used regardless of the size of a messages exceeding a maximum message size or the size of an IE exceeding a certain size; whether and how the interface setup request message is fragmented.

5. The method according to any one of claims 1-4, further comprising: sending (1001 , 1101 , 1201,1503) a first message to the second network node (812), wherein the first message comprises information on message fragmentation of an original message or information on list fragmentation of a list type IE contained in the original message to be sent to the second network node (812).

6. The method according to claim 5, wherein the first message comprises any one or a combination of the following: a list describing fragmentation of the original message; a list describing fragmentation of the one or more list type lEs contained in the original message; a list of partial copies of the original message; a number of fragments of the original message or the list type IE contained in the original message being split; a length or size of each fragment; a partial copy or a fragment of the original message; a fragment of lists of the list type IE.

7. The method according to claim 6, wherein a partial copy or a fragment of the original message comprises one or more of the following: the name of the one or more list type lEs being fragmented; a unique identifier for each fragment of lists; the number of fragments in which the original message or the list type IE contained in the original message is fragmented; for each fragmented list type IE, the frame number of the current fragment of lists, if a fragment of lists is contained in the first message; for each fragmented list type IE, the size of the current fragment of lists, if a fragment of lists is contained in the first message; the maximum size the first network node (811) can receive for list type lEs , if not already provided; the overall size of the list type IE, when taking all fragments into account.

8. The method according to claim 6, wherein each fragment of lists comprises one or more following elements: a name of the list type IE being fragmented; a unique identifier for the fragment of lists; a current number of the fragment of lists; a length or size of the fragment of lists.

9. The method according to any one of claims 1-8, further comprising: sending (1504) to the second network node (812) a second message comprising a fragment of the original message or a fragment of lists of the list type IE contained in the original message.

10. The method according to claim 9, wherein the second message comprises one or more of the following lEs:

List Name,

Maximum List Size,

Fragmentation ID,

Number of Fragments,

Fragment number, Fragment length.

11 . The method according to any one of claims 5-10, further comprising retransmitting a message containing a fragment of the original message or a fragment of lists of a list type IE contained in the original message, which is not received by the second network node (812) in response to a message received from the second network node (812) indicating the missing fragment of the original message or missing fragment of lists.

12. The method according to any one of claims 1-11 , wherein the first message is sent using an existing interface message between the first and second network nodes.

13. The method according to any one of claims 1-11 , wherein the first message is sent using an encapsulating message introduced between the first and second network nodes, wherein the encapsulating message comprises at least one fragment of the original message.

14. The method according to claim 13, wherein a plurality of encapsulating messages are sent from the first network node (811) to the second network node (812).

15. The method according to any one of claims 13-14, wherein the encapsulating message comprises one or more of: an identifier of the message for which a fragment is being transferred within the encapsulating message; an identifier of the fragment being transferred within the encapsulating message; the number of fragments in which the original message has been fragmented; an indication indicating whether the fragment being transferred in the encapsulating message is the first fragment or the last fragment; whether a subsequent fragment for the same original message referenced by an identifier can be expected.

16. The method according to any one of claims 1-15, further comprising: sending (1301 , 1505) a measurements request message to the second network node (812), wherein the measurements request message comprises one or more lists of measurements requested by the first network node (811); receiving (1302, 1506) a measurements response message from the second network node (812), wherein the measurements response message comprises information on message fragmentation.

17. The method according to claim 16, wherein each list of measurements requested by the first network node (811) comprises one or more of the following information: if fragmentation of the list of measurements is allowed or not; a maximum number of fragments a list of measurements may be fragmented into; a maximum number of items a list of measurements may contain; a maximum number of items a fragment of the list may contain.

18. The method according to any one of claims 16-17, further comprising: receiving (1303, 1304, 1506a) one or more measurements report messages from the second network node (812), wherein each measurements report message comprises a fragment of the lists of measurements.

19. The method according to any one of claims 1-15, further comprising: sending (1507) a first measurements request message to the second network node (812); receiving (1508) a response from the second network node (812) in response to the first measurements request message; sending (1509) a second measurements request message to the second network node (812); receiving (1510) a response from the second network node (812) in response to the second measurements request message; receiving (1511) a measurements report message from the second network node (812), wherein the measurements report message comprises an aggregated message of reporting messages in response to the first and second requested measurements.

20. The method according to claim 19, wherein the aggregated message comprises a list of messages been aggregated, and each item of the list comprises: a message type or a message identifier; a bitstring containing one message.

21. The method according to claim 19, wherein the aggregated message comprises multiple datasets belonging to different measurements requests, and comprises one or more of the following information: a list of identifiers identifying the different measurements requests; a list of datasets pertaining to the request identifiers.

22. The method according to any one of claims 1-21 , wherein when the first network node (811) is sending or receiving periodic messages according to a first periodicity, the method further comprises: when it is determined that the sending or receiving signaling intensity caused at least in part by the sending or receiving of the periodic messages exceeds a first threshold, sending (1512) a first notification to the second network node (812) to notify one or more of the following: continue sending the periodic messages according to the first periodicity is no longer possible, sending of the periodic messages according to the first periodicity is paused, the maximum signaling intensity rate is exceeded, maintaining the current periodic update with a second periodicity; when it is determined that the signaling intensity decreases below a second threshold, sending (1513) a second notification to the second network node (812) to notify one or more of the following: sending of the periodic messages according to the first periodicity is possible, sending of the periodic messages according to the first periodicity is resumed, maintaining the current periodic update according to the first periodicity.

23. The method according to any one of claims 1-21 , wherein when the first network node (811) is sending or receiving fragmented messages, the method further comprises: when it is determined that signaling intensity exceeds a first threshold, sending (1512) a first indication to the second network node (812) to indicate: sending/receiving of the fragmented messages can continue until all the fragments are sent/received, or sending/receiving of the fragmented message fails, or sending/receiving of the fragmented message is paused.

24. The method according to any one of claims 1-23, wherein the first and second network nodes belong to different radio access technologies.

25. A method performed in a second network node (812) for handling message signaling to a first network node (811) in a wireless communication network (800), the method comprising: receiving (1601) an interface setup request message from the first network node (811), wherein the interface setup request message comprises one or more parameters indicating characteristics of signaling messages of the first network node (811); sending (1602) a response to the first network node (811), wherein the response comprises one or more parameters indicating any one of: acceptance of one or more of the characteristics of signaling messages of the first network node (811), a cause for failure of receiving the interface setup request message, characteristics of signaling messages of the second network node (812); receiving (1603) a first message from the first network node (811), wherein the first message comprises information on message fragmentation of an original message or information on list fragmentation of a list type Information Element, IE, contained in the original message.

26. The method according to claim 25, wherein the characteristics of signaling messages of the first/second network node (812) comprises any one or more the following: a maximum size of a message can be sent or received by the first/second network nodes (811/812); a maximum IE size of a specific type can be sent or received by the first/second network nodes (811/812); a maximum signaling intensity acceptable or allowed by the first/second network nodes (811/812); a maximum sending or receiving rate acceptable or allowed by the first/second network nodes (811/812); a maximum message sending or receiving frequency acceptable or allowed by the first/second network nodes (811/812); a maximum number of fragments the first/second network node (811 , 812) is able to receive for a split message; a maximum number of fragments the first/second network node (811 , 812) is able to receive for a split IE of a specific type.

27. The method according to any one of claims 25-26, wherein a cause for failure of receiving the interface setup request message is due to a too large interface setup message.

28. The method according to any one of claims 25-27, further comprising: receiving (1604) a second message comprising a fragment of the original message or a fragment of lists of a list type IE contained in the original message.

29. The method according to any one of claims 25-28, further comprising: sending (1605) a message to the first network node (811) indicating a missing fragment of the original message or missing fragment of lists.

30. The method according to any one of claims 25-29, further comprising: receiving (1301 , 1606) a measurements request message from the first network node (811), wherein the measurements request message comprises one or more lists of measurements requested by the first network node (811); sending (1302, 1607) a measurements response message to the first network node (811), wherein the measurements response message comprises information on message fragmentation.

31. The method according to claim 30, further comprising: sending (1303, 1304, 1608) one or more measurements report messages to the first network node (811), wherein each measurements report message comprises a fragment of the lists of measurements.

32. The method according to any one of claims 25-29, further comprising: receiving (1401 , 1610) a first measurements request message from the first network node (811); sending (1402, 1611) a response to the first network node (811) in response to the first measurements request message; receiving (1403, 1612) a second measurements request message from the first network node (811); sending (1404, 1613) a response to the first network node (811) in response to the second measurements request message; sending (1405, 1614) a measurements report message to the first network node (811), wherein the measurements report message comprises an aggregated message of reporting messages in response to the first and second requested measurements.

33. The method according to claim 32, wherein the aggregated message comprises a list of messages been aggregated, and each item of the list comprises: a message type or a message identifier; a bitstring containing one message.

34. The method according to claim 32, wherein the aggregated message comprises multiple datasets belonging to different measurements requests, and comprises one or more of the following information: a list of request identifiers identifying the different measurements requests; a list of datasets pertaining to the request identifiers.

35. A first network node (811) configured to perform the method according to any one of claims 1-23 for handling message signaling to a second network node (812) in a wireless communication network (800).

36. A second network node (812) configured to perform the method according to any one of claims 25-34 for handling message signaling to a first network node (811) in a wireless communication network (800).