Communication network components and methods for re - establishing communication connections

Abstract

According to various embodiments, a communications network component is described that includes: a memory configured to store, for each of a plurality of base stations, for each of a plurality of connections provided by the base station, mobile terminal context information for the connection; an input interface configured to receive from a radio access network component a request for mobile terminal context information for a connection previously provided by one of the base stations for a mobile terminal; a determiner configured to determine, from the stored mobile terminal context information, mobile terminal context information for the connection previously provided by the one of the base stations for the mobile terminal; and an output interface configured to transmit to the radio access network component the mobile terminal context information for the connection previously provided by the one of the base stations for the mobile terminal.

Description

Technical Field

[0001] The present disclosure relates to communication network components and methods for re - establishing communication connections.

Background Art

[0002] In the case of a failure of a base station that provides a communication connection to a mobile terminal, for example, in a wireless access network, it is usually desirable for the communication connection to be re - established quickly. For a quick re - establishment, the "new" base station, i.e., the base station that provides the re - established communication connection, requires mobile terminal context information such as a security context (e.g., an encryption key) and various other parameters that delay reselection (which actually means that a new connection is established rather than the previous connection being re - established). However, it may not be easy or even possible for the new base station to obtain the mobile terminal context information.

[0003] Therefore, an approach that can obtain mobile terminal context information for re - establishing a communication connection is desirable.

Summary of the Invention

[0004] According to various embodiments, a communication network component, for each of a plurality of base stations, for each of a plurality of connections provided by the base station, a memory configured to store mobile terminal context information for the connection; an input interface configured to receive, from a wireless access network component, a request for mobile terminal context information for a connection previously provided by one of the base stations for the mobile terminal; a determiner configured to determine, from the stored mobile terminal context information, the mobile terminal context information for the connection previously provided by the one of the base stations for the mobile terminal; An output interface configured to transmit the mobile terminal context information for the connection previously provided by the one of the base stations to the wireless access network component for the mobile terminal; A communication network component including is provided.

Brief Description of the Drawings

[0005] In the drawings, like reference numerals generally represent like parts throughout different figures. The drawings are not necessarily to scale, but rather are generally emphasized when explaining the principles of the present invention. In the following description, various aspects are described with reference to the following drawings.

Figure 1

Figure 2

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Figure 4

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Figure 6

Modes for Carrying Out the Invention

[0006] The following detailed description refers to the accompanying drawings that show specific details and aspects in which the present invention may be implemented, using the figures. Other aspects may be utilized and structural, logical, and electrical changes may be made without departing from the scope of the present invention. The various aspects of the present disclosure are not necessarily mutually exclusive, and some aspects of the present disclosure may be combined with one or more other aspects of the present disclosure to form new aspects.

[0007] Various examples corresponding to aspects of the present disclosure are described below.

[0008] Example 1 is a communication network component as described above.

[0009] In Example 2, the base station is a base station of a first radio access network, the radio access network component is a component of a second radio access network, and the first radio access network is composed of base stations other than the second radio access network. It is the communication network component described in Example 1.

[0010] In Example 3, the radio access network component is a base station of the second radio access network, and it is the communication network component described in Example 2.

[0011] In Example 4, the communication network component receives, from the radio access network component, identification information associated with one of the base stations and identification information of the base station for which the communication connection should be re-established. Among the plurality of base stations, it identifies a base station that matches the identification information associated with one of the base stations in the vicinity of the base station for which the communication connection should be re-established, and determines the mobile terminal context information stored for the identified base station as the mobile terminal context information for the previous connection provided by the one of the base stations. It is configured to determine the mobile terminal context information for the previous connection provided by one of the base stations for the mobile terminal, and it is the communication network component according to any one of Examples 1 to 3.

[0012] In Example 5, among the plurality of base stations, by identifying the base station closest to the base station for which the communication connection should be re-established between the base stations, it identifies a base station that conforms to the identification information of one of the base stations and is in the vicinity of the base station for which the communication connection should be re-established. It is the communication network component described in Example 4.

[0013] Example 6 is the communication network component according to Example 5, which stores topology information of the arrangement of the plurality of base stations and / or the radio access network to which the base station to re-establish the communication connection belongs, and uses the topology information to identify a base station that matches the identification information of the one base station among the base stations and is in the vicinity of the base station to re-establish the communication connection.

[0014] Example 7 is the communication network component according to any one of Examples 1 to 6, wherein the connection is a radio resource control layer connection.

[0015] Example 8 is such that the mobile terminal context information a network slice identifier of a network slice that provides a communication service via the communication connection, an identifier of an access and mobility management function that processes the communication connection, an identifier of an access point for communication between the one base station among the base stations and the access and mobility management function that processes the communication connection, an identifier of each of one or more data radio bearers associated with the communication connection, identifiers of a central unit and a distributed unit of the one base station among the base stations, a security context of the communication connection, an identifier of the mobile terminal, a transport layer address parameter of the communication connection, and includes one or more of the above, and is the communication network component according to any one of Examples 1 to 7.

[0016] Example 9 is a communication network component according to any one of Examples 1 to 8, wherein the memory is configured to store mobile terminal context information for a connection provided by a base station provided by a different public land mobile network, and for each public land mobile network, the mobile terminal context information stored for a connection provided by the public land mobile network is stored in association with identification information of the public land mobile network.

[0017] Example 10 is a communication network component according to any one of Examples 1 to 9, wherein the input interface is configured to receive the request from the radio access network component via another communication network component that stores mobile terminal context information.

[0018] Example 11 is a communication network comprising a communication network component according to any one of Examples 1 to 10, and including the radio access network component, wherein the radio access network is configured to receive a request for re - establishing the communication connection, determine whether it can obtain the mobile terminal context information from one of the base stations, and if it cannot obtain the mobile terminal context information from one of the base stations, transmit a request for the mobile terminal context information to the communication network component.

[0019] Example 12 is the communication network according to Example 11, further including the plurality of base stations, and each base station is configured to store mobile terminal context information for a connection in the communication network component for each of the plurality of connections provided by the base station.

[0020] Example 13 is the communication network according to Example 12, wherein each base station is configured to construct the mobile terminal context information for providing the connection, copy the mobile terminal context information to the communication network component, and maintain the mobile terminal context information for providing the connection.

[0021] Example 14 is a method for re - establishing a communication connection as shown in FIG. 6.

[0022] It should be noted that one or more of the features of any of the above - mentioned examples may be lacking in any one of the other examples. In particular, the examples described in the context of the apparatus are equally valid for the method.

[0023] According to a further embodiment, there is provided a computer - readable medium including a computer program and instructions that, when executed by a computer, cause the computer to execute the method according to any one of the above - mentioned examples.

[0024] In the following, various examples will be described in more detail.

[0025] FIG. 1 shows a wireless communication system 100 configured according to 5G (fifth generation), for example, as specified by 3GPP (Registered Trademark) (Third Generation Partnership Project), that is, according to 5GS for example.

[0026] The wireless communication system 100 includes mobile wireless terminal devices 102 such as UE (user equipment), nano equipment (NE), etc. The mobile wireless terminal device 102 is also called a subscriber terminal and forms the terminal side. On the other hand, the other components of the wireless communication system 100 described below are parts of the mobile wireless communication network side, that is, parts of a mobile wireless network (for example, a Public Land Mobile Network (PLMN)).

[0027] Furthermore, the wireless communication system 100 includes a wireless access network 103 including a plurality of wireless access network nodes, that is, base stations configured to provide wireless access in accordance with 5G (fifth generation) wireless access technology (5G New Radio). It should be noted that the wireless communication system 100 may be configured in accordance with LTE (Long Term Evolution) or another mobile wireless communication standard, but 5G is used as an example in this specification. Each wireless access network node 103 may provide wireless communication with the mobile wireless terminal device 102 via a wireless interface. It should be noted that the wireless access network 103 may include any number of wireless access network nodes.

[0028] The wireless communication system 100 further includes a core network (CN, here 5GC) 108 including an Access and Mobility Management Function (AMF) 101 connected to the RAN 103 and a Unified Data Management (UDM) 104. Here and in the following examples, the UDM may further include an actual UE subscription database known, for example, as a UDR (Unified Data Repository). The core network 108 further includes an Authentication Server Function (AUSF) 109 and one or more Policy Control Functions, in this example, a first PCF 106 and a second PCF 107.

[0029] The core network 108 further includes a plurality of session management functions (Session Management Function (SMF)), in this example, a first session management function (SMF) 110 and a second session management function (SMF) 112, and a plurality of user plane functions (User Plane Function (UPF)), in this example, a first user plane function (UPF) 111 and a second user plane function (UPF) 113. The SMFs 110, 112 are for processing PDU (Protocol Data Unit) sessions, that is, for generating, updating, and deleting PDU sessions, and for managing session contexts by the user plane function (UPF).

[0030] The core network 108 further includes an application function (AF) 105. Although the AF 105 is shown as being directly connected to the SMFs 110, 112 and the PCFs 106, 107, it may be connected to them via a NEF (Network Exposure Function) especially when the AF 105 is maintained by a third party.

[0031] The AF 105 enables an application to request that the 5G system 100 support specific QoS (Quality of Service) policies for a UE 102 that establishes a PDU session to provide a communication service for the application.

[0032] RAN103 may fail, which may cause the communication service, such as the connection to the application server, to be interrupted. In such a case, it is desirable to quickly establish an alternative connection. This is particularly applicable to traffic that requires (or should provide) high reliability and / or low latency, such as URLLC (Ultra Reliable Low Latency Communications) traffic. It should be noted that this is also desirable in cases where there are other abnormal conditions, such as a significant loss of service quality, e.g., latency or throughput, rather than a complete failure of RAN103. Therefore, an alternative connection can be established using the second RAN.

[0033] Figure 2 shows a scenario where the UE201 is connected to the server 204 (an edge server denoted as E1 here) via the first RAN202 and the first UPF203.

[0034] When a failure (or other abnormal condition) occurs in the first RAN202, the second RAN205 that the UE201 can use to connect to the server 204 is available.

[0035] When connecting to the server 204 using the first RAN202, the UE201 communicates wirelessly with the first base station (gNodeB or gNB in 5G) 206 shown as the "old gNB" of the first RAN202 (since it was used before the failure). Specifically, the UE201 uses the radio cell provided by the old gNB206 (referred to as the "old" radio cell). When connecting to the server 204 using the second RAN205, the UE201 communicates wirelessly with the second base station 207 shown as the "new gNB" or "target gNB" of the second RAN205 (since it is used after the failure). Specifically, the UE201 uses the radio cell provided by the new gNB207 (referred to as the "new" radio cell).

[0036] To achieve a rapid re - establishment of communication services, when the first RAN202 fails, UE201 requests RRC (Radio Resource Control) re - establishment from the new gNB207.

[0037] UE201 provides the PCI (physical cell identifier) of the old radio cell in the RRC re - establishment request message to the new gNB207. UE201 also provides the C - RNTI (cell radio network temporary identity). In the current scenario, since the UE context is not locally available, the new gNB207 tries to discover the old gNB206 to request the UE context. For this purpose, the new gNB207 checks the NCRT (neighbour cell relation table) that maps the PCI to the NCI for the PCI and NCI (new radio cell ID) to determine the old gNB206.

[0038] When the old gNB206 is discovered in this way, the new gNB207 fetches the UE context from the old gNB206. If the old gNB206 cannot be found, the new gNB207 sends an RRC rejection message to UE201 in response to the RRC connection re - establishment request.

[0039] This means that when the new gNB207 cannot discover the old gNB206 (i.e., it cannot connect to the old gNB206 and cannot obtain the UE context of the failed connection), UE201 needs to request the establishment of a new RRC connection from the new gNB207.

[0040] When UE201 sends a request for the establishment of a new RRC connection, the new gNB207 communicates with the AMF101 to establish a new UE context for the new gNB207.

[0041] Therefore, if a failure (e.g., a hardware failure or a software failure) occurs in the old gNB (and thus it becomes unavailable), the new gNB 207 will attempt to find the old gNB 206 based on the NCRT / NRT (Neighbor Relation Table) information. However, since the old gNB is unavailable, the new gNB 206 cannot find the old gNB 206 and will reject the UE's request.

[0042] Furthermore, it may not be easy for the new gNB 207 to find the old gNB 206 (even if there is no failure in the old gNB 207 itself). This is because although the PCI holds certain information for identifying the old gNB 206, it can only have one of 1008 values of NR (new radio), is not globally unique, and the second RAN 205 may not have the NRT information of the first RAN 204.

[0043] The NR cell identification information (NR Cell Identity (NCI)) has a total size of 36 bits and is unique. The NR cell global identifier (NR Cell Global Identifier (NCGI)) is used to globally identify the NR cell. The NR cell identification information (NR Cell Identity (NCI)) is broadcast within SIB#1 (system information block number 1). However, in the NSA (non-standalone) configuration (in the EN-DC setup), since the NR base station does not broadcast the NCI of the SIB#1 information, the UE cannot decode and report the CGI (cell global identity) information.

[0044] According to various embodiments, the simplification of RAN failures that process UE contexts in the RAN is stored in a centralized function, enabling RRC re - establishment instead of establishing a new RRC connection (even if the old gNB is unavailable or cannot be identified by the new gNB), which can reduce the service interruption of the UE in case of RAN failures. For this purpose, functions and / or parameters with corresponding logic within the RAN node (base station) can be added to the Xn interface.

[0045] Specifically, according to various embodiments, each time the RAN (e.g., the first RAN 202) accepts a UE (i.e., there is UE Initial Access) and / or a PDU session is established, the RAN 202 creates or updates the UE context stored in the UE context storage component 208, i.e., the centralized storage function (CSF) of the RAN.

[0046] The CSF 208 is used by the first RAN 202 to update or discard the UE context, and supports the handling of failures of the first RAN 202, for example, by exposing an interface (e.g., standardized) that can be referenced by the new gNB 207 in case of a failure of the first RAN 202.

[0047] The CSF 208 can be part of the gNB - CU (centralized unit). In this case, all related gNB - DUs (distributed units) store the context in the CSF 208. Alternatively, the CSF 208 can be a stand - alone function. In this case, all gNB - CUs and / or gNB - DUs store the context in the CSF 208.

[0048] Table 1 shows exemplary elements of the UE context that can be stored in the CSF 208. Table 1

Table 1

[0049] Figure 3 shows a flowchart 300 for processing RAN failures according to an embodiment.

[0050] UE 301 corresponding to UE 201, first RAN 302 corresponding to first RAN 202, CSF 303 corresponding to CSF 208, and second RAN 304 corresponding to second RAN 205 are involved in the flow.

[0051] At 305, the UE establishes an RRC connection with the first RAN 302.

[0052] At 306, the first RAN 302 (e.g., old gNB 206) stores the UE context in the CSF 303, associated with the ID of the old gNB used by the first UE 301 and the PCI ID of the cell of the first RAN 302.

[0053] At 307, it is assumed that there is a failure in the first RAN 302. The failure can be, for example, a hardware failure, a software failure, a radio link failure, a reconfiguration failure, an integrity check failure, etc.

[0054] To avoid a (long) service interruption, at 308, the UE 301 requests an RRC re - establishment from the second RAN 304, which indicates the ( "old") PCI ID and C - RNTI of the connection to the first RAN 302.

[0055] It is assumed that the second RAN 304 cannot retrieve the UE context from the first RAN 307 because, for example, the old gNB 206 is unavailable, or the new gNB 207 cannot identify the old gNB (or even the first RAN 207) by the PCI ID + C - RNTI.

[0056] Therefore, at 310, the second RAN 304 (for example, specifically the new gNB 207) sends a UE context search request to the CSF 303. The UE context search request includes the ID of the new gNB provided by the UE 301 at 308, the "old" PCI ID, and the C-RNTI. The old PCI ID can be considered as the identification information associated with the old gNB.

[0057] At 311, the CSF 303 looks for a gNB (i.e., a RAN node) that has a neighboring relationship with the new gNB of the second RAN 202 (i.e., the sender of the request at 310) (for example, is adjacent, or has overlapping or adjacent coverage areas), and is associated with the cell related to the old PCI. Next, the CSF 303 extracts the information (i.e., the UE context) stored under the PCI and corresponding to the C-RNTI of the found gNB.

[0058] At 312, the CSF 303 provides the UE context to the second RAN 304.

[0059] Next, at 313, the second RAN 304 (specifically the new gNB 307) re-establishes the RRC connection and allocates one or more DRBs (data radio bearers) to the UE 301.

[0060] The old gNB and the new gNB can be represented at 306 and 310 respectively using the global RAN node ID (RAN ID).

[0061] At 311, the CSF 303 can use the topology information of the first RAN 307 and the second RAN 304 as shown in Table 2 as an example. Table 2 [Table 2]

[0062] Note that it is also possible to share CSF303 among multiple PLMNs (Public Land Mobile Networks). In this case, the old gNB and the new gNB can include the PLMN ID (PLMN identifier) during the context storage or retrieval process. Furthermore, the CSF can also be deployed in a non-public network (NPN) and can be shared between the PLMN and the NPN.

[0063] Furthermore, in a communication network, for example, it is also possible to deploy multiple CSF303s in different locations. In this case, these CSFs are interconnected and exchange the stored information. For example, the UE provides the location information where it attached to the old gNB, and the new gNB forwards it to the new CSF. The new CSF uses this location information to discover the old CSF and extract the context. In this case, multiple CSFs can be regarded as communication network components of UE context information implemented in a distributed manner (such as multiple CSFs), or it can be seen that the request for mobile terminal context information of the RAN component is received via another CSF.

[0064] Figure 4 shows an example of the use of CSF in a C-RAN (Cloud RAN) architecture.

[0065] In this case, the CU-CPs 401 and 402 of the first gNB 403 and the second gNB 404 may be connected to the CSF 405 via the service-based interfaces 406 and 407.

[0066] In summary, according to various embodiments, the communication network component is provided as shown in FIG. 5.

[0067] FIG. 5 shows a communication network component 500 according to an embodiment.

[0068] The communication network component 500 (CSF in the above example) includes a memory 501 configured to store mobile terminal context information for each of a plurality of connections provided by each of a plurality of base stations.

[0069] Furthermore, the communication network component 500 includes an input interface 502 configured to receive a request for mobile terminal context information for a connection previously provided by one of the base stations for the mobile terminal from a radio access network component.

[0070] The communication network component 500 further includes a determiner 503 configured to determine, from the stored mobile terminal context information, the mobile terminal context information for a connection previously provided by one of the base stations for the mobile terminal, and an output interface 504 configured to transmit the mobile terminal context information for the connection previously provided by one of the base stations for the mobile terminal to the radio access network component.

[0071] According to various embodiments, in other words, a centralized memory function is introduced for the mobile terminal (e.g., UE) context to enable handling of RAN failures, i.e., the UE context is maintained in the centralized memory of the communication system.

[0072] The approach of FIG. 5 enables rapid recovery of the UE context from the RAN to handle RAN failure scenarios. By managing and maintaining the UE context within the network, the impact on the UE can be avoided and high reliability can be achieved.

[0073] The communication network component (also considered a mobile terminal context information storage component) can be configured to receive mobile terminal context information for connections from a plurality of base stations and store them upon reception (e.g., via its input interface).

[0074] The communication network component executes, for example, a method as shown in FIG. 6.

[0075] FIG. 6 shows a flowchart 600 showing a method for re - establishing a communication connection.

[0076] At 601, for each of a plurality of base stations, for each of a plurality of connections provided by the base station, mobile terminal context information for the connection is stored.

[0077] At 602, a request for mobile terminal context information for a connection previously provided by one of the base stations for the mobile terminal is received from a radio access network component.

[0078] At 603, mobile terminal context information for a connection previously provided by one of the base stations for the mobile terminal is determined from the stored mobile terminal context information.

[0079] At 604, mobile terminal context information for a connection previously provided by one of the base stations for the mobile terminal is transmitted to the radio access network component.

[0080] Components of the communication network component (e.g., a determiner and an interface) may be implemented, for example, by one or more circuits. A "circuit" may be understood as any kind of logic implementation entity, which may be a dedicated circuit or a processor that executes software, firmware, or any combination thereof stored in a memory. Thus, a "circuit" may be a programmable processor, such as a hard - wired logic circuit or a programmable logic circuit like a microprocessor. A "circuit" may also be a processor that executes software, such as any kind of computer program. Any other kind of implementation of each of the above - described functions may also be understood as a "circuit".

[0081] While particular embodiments have been described, those skilled in the art will understand that various changes in form and detail may be made without departing from the spirit and scope of the aspects of the disclosure as defined in the appended claims. The scope is thus indicated by the appended claims and is to include all changes within the equivalent meaning and scope of the claims.

Claims

1. A communication network component, for each of a plurality of base stations, for each of a plurality of communication connections provided by the base station, a memory configured to store mobile terminal context information for the communication connection; an input interface configured to receive, from a radio access network component, a request for mobile terminal context information for a communication connection previously provided by one of the base stations for a mobile terminal; a determiner configured to determine, from the stored mobile terminal context information, mobile terminal context information for the communication connection previously provided by the one of the base stations for the mobile terminal; an output interface configured to transmit the mobile terminal context information for the communication connection previously provided by the one of the base stations for the mobile terminal to the radio access network component; A communication network component comprising the above.

2. The base station is a base station of a first radio access network, the radio access network component is a component of a second radio access network, and the first radio access network is composed of base stations other than the second radio access network. The communication network component according to claim 1.

3. The radio access network component is a base station of the second radio access network. The communication network component according to claim 2.

4. The communication network component receives, from the radio access network component, identification information associated with the one base station among the base stations and identification information of the base station for which the communication connection is to be re-established, identifies a base station among the plurality of base stations that matches the identification information associated with the one base station in the vicinity of the base station for which the communication connection is to be re-established, and determines the mobile terminal context information stored for the identified base station as the mobile terminal context information for the previously provided communication connection, thereby being configured to determine the mobile terminal context information for the previously provided communication connection by the one base station among the base stations for the mobile terminal. The communication network component according to claim 3.

5. The communication network component according to claim 4, wherein among the plurality of base stations, a base station closest to the base station for which the communication connection is to be re-established among the base stations is identified, thereby identifying a base station that matches the identification information of the one base station among the base stations and is in the vicinity of the base station for which the communication connection is to be re-established.

6. The communication network component according to claim 5, which stores topology information of the arrangement of the plurality of base stations and / or the radio access network to which the base station for which the communication connection is to be re-established belongs, and is configured to use the topology information to identify a base station that matches the identification information of the one base station among the base stations and is in the vicinity of the base station for which the communication connection is to be re-established.

7. The communication network component according to claim 6, wherein the communication connection is a radio resource control layer connection.

8. The mobile terminal context information is a network slice identifier of a network slice that provides a communication service via the communication connection, an identifier of an access and mobility management function that processes the communication connection, An identifier of an access point for communication between the one base station among the base stations and the access and mobility management function that processes the communication connection An identifier of each of one or more data radio bearers associated with the communication connection Identifiers of a central unit and a distributed unit of the one base station among the base stations A security context of the communication connection An identifier of the mobile terminal Transport layer address parameters of the communication connection The communication network component according to claim 7, including one or more of the above

9. The memory is configured to store mobile terminal context information for communication connections provided by base stations provided by different public land mobile networks, and for each public land mobile network, the mobile terminal context information stored for communication connections provided by the public land mobile network is stored in association with the identification information of the public land mobile network. The communication network component according to claim 8

10. The input interface is configured to receive the request from the radio access network component via another communication network component that stores mobile terminal context information. The communication network component according to claim 9

11. A communication network, Including the communication network component according to any one of claims 1 to 10, and including a radio access network component, The wireless access network component receives a request for re - establishment of the communication connection, determines whether it can obtain the mobile terminal context information from the one base station among the base stations, and if it cannot obtain the mobile terminal context information from the one base station among the base stations, is configured to send a request for the mobile terminal context information to the communication network component.

12. Further including the plurality of base stations, each base station is configured to store mobile terminal context information for the communication connection in the communication network component for each of the plurality of communication connections provided by the base station. The communication network according to claim 11.

13. Each base station is configured to construct the mobile terminal context information for providing the communication connection, copy the mobile terminal context information to the communication network component, and maintain the mobile terminal context information for providing the communication connection. The communication network according to claim 12.

14. A method for re - establishing a communication connection, For each of the plurality of base stations, for each of the plurality of communication connections provided by the base station, storing mobile terminal context information for the communication connection; Receiving, from a wireless access network component, a request for mobile terminal context information for a communication connection previously provided by one of the base stations for a mobile terminal; Determining, among the stored mobile terminal context information, the mobile terminal context information for the communication connection previously provided by the one of the base stations for the mobile terminal; Sending the mobile terminal context information for the communication connection previously provided by the one of the base stations for the mobile terminal to the wireless access network component; A method comprising

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