A signaling proxy architecture and unified signaling processing method for 4g and 5g converged core network

Abstract

A signaling proxy architecture and unified signaling processing method for a 4G and 5G converged core network, which terminates the 4G traditional signaling protocol stack in an independently deployed converged proxy network element Proxy, maintains the purity and simplicity of the 5G architecture, can reuse the development framework and tool chain, reduces the skill threshold and learning cost, and improves the maintenance efficiency; in view of the problem that the Diameter and GTPv2-C protocols based on fixed IP communication cannot be elastically scaled in a cloud native environment, the Proxy exposes a stable virtual IP as a southbound access address through a container service, so that the increase and decrease of the Proxy instance is completely transparent; the Proxy adopts a stateless architecture separating computation from storage, and externalizes all user session contexts to a distributed in-memory database cluster, so that new instances are immediately available when scaling out, and graceful disconnection is realized through a drainage mechanism and peer connection termination request / peer connection termination response to realize zero-interruption migration of sessions when scaling in.

Description

Technical Field

[0001] This invention belongs to the field of communication technology, specifically relating to a signaling proxy architecture and unified signaling processing method for 4G and 5G converged core networks. Background Technology

[0002] With the commercial deployment of 5G, the fifth-generation mobile communication technology, global operators face the reality of long-term coexistence of 4G and 5G networks. During the convergence transition phase, 4G EPC and 5GC need to interoperate to support seamless mobility management and session continuity for users across 4G and 5G networks. In this evolution process, to ensure service continuity for existing 4G users while fully leveraging the cloud-native architecture advantages of 5GC, the industry has proposed the concept of a converged 4G and 5G core network, which handles both 4G and 5G services simultaneously on the same core network platform.

[0003] Existing converged core network solutions mainly adopt the "network element embedded convergence" strategy, referring to Figure 1 This means integrating both 4G and 5G protocol stacks within a 5G network element. Typical converged network elements include: SMF / PGW-C converged network element: Session management function. The SMF integrates the PGW control plane PGW-C function, which must simultaneously support the 5G N4 interface (PFCP protocol), N7 interface (HTTP / SBI protocol), and the 4G S5 / S8 interface (GTPv2-C protocol) and Gx interface (Diameter protocol); UDM / HSS converged network element: Unified data management. The UDM integrates the Home Subscriber Server (HSS) function, which must simultaneously support the 5G Nudm series SBI interface (HTTP protocol) and the 4G S6a interface (Diameter protocol); UPF / PGW-U converged network element: User plane function. The UPF integrates the PGW user plane PGW-U, which must simultaneously support the 5G N3 / N9 interface and the 4G S1-U / S5-U interface (both based on the GTP-U protocol). While the aforementioned "embedded convergence of network elements" solution can functionally meet the interoperability requirements of 4G and 5G, it has the following significant drawbacks:

[0004] Impure architecture and compromised service-oriented design: Embedded converged solutions force 5G network elements to integrate both the heavy traditional protocol stack Diameter and GTPv2-C. These traditional protocols are in fundamental conflict with the design philosophy of HTTP microservices, undermining the purity and simplicity of the service-based architecture SBA.

[0005] High development and maintenance costs: Embedded converged solutions require R&D personnel to master the underlying implementation details of traditional communication protocols, including but not limited to: (1) Diameter protocol attribute value pair AVP encoding and decoding, command code processing, and result code mapping; (2) GTPv2-C protocol information element IE encoding and decoding, type-length-value TLV format processing, and BearerContext composite IE nesting parsing. The above cross-protocol stack R&D requirements significantly increase the development cycle and testing workload, delaying the commercialization of converged core networks.

[0006] Cloud-native elastic scaling is hampered: In cloud-native deployment environments (such as Kubernetes), the IP addresses of container instances (Pods) are dynamically assigned by the platform, and the IP changes after the Pod is destroyed and rebuilt. However, both the Diameter and GTPv2-C protocols are based on a fixed IP peering communication model: the MME must pre-configure the fixed IP address of the HSS to establish an S6a Diameter peering connection, and simultaneously configure the fixed IP address of the SGW to send S11 GTPv2-C signaling. When converged network elements carrying these protocols are deployed on a cloud-native platform, there is a fundamental conflict between the dynamic changes of Pod IPs and the fixed IP addresses required by the protocols, preventing converged network elements from performing elastic scaling as freely as 5G HTTP microservices. Furthermore, converged network elements typically maintain a large number of stateful user session contexts in process-local memory; the addition or removal of instances directly leads to the loss or inconsistency of session state, further exacerbating the difficulties of cloud-native scaling. Summary of the Invention

[0007] To address the problems existing in the aforementioned background technology, this invention proposes a signaling proxy architecture and a unified signaling processing method for 4G and 5G converged core networks. Based on a pure 5G service architecture, it realizes a 4G and 5G converged core network, significantly reducing development and maintenance costs, unifying the elastic scaling mechanism, achieving zero-interruption elastic scaling, and fully possessing cloud-native hot migration capabilities.

[0008] A signaling proxy architecture for a converged 4G and 5G core network includes a 4G Mobility Management Entity (MME), a converged proxy network element (Proxy), and a 5G core network element group (5GC NFs); wherein,

[0009] The 4G Mobile Management Entity (MME) is responsible for the access management, mobility management, and bearer management of 4G terminals. It interacts with the Home Subscriber Server (HSS) to obtain subscription data and authentication vectors, and interacts with the Server Gateway (SGW) to manage the Evolved Packet System (EPS) bearer.

[0010] The integrated proxy network element is deployed independently between the MME and 5GC, including a southbound protocol adaptation module, a protocol conversion engine, a context management module, and a northbound SBI client module;

[0011] The southbound protocol adaptation module includes Diameter protocol endpoints and GTPv2-C protocol endpoints to implement the Diameter basic protocol stack and GTPv2-C protocol stack; the protocol conversion engine implements 4G→5G forward conversion and 5G→4G reverse conversion, and saves the parameter mapping rule table between 4G parameters and 5G parameters; the context management module includes EPS session context cache and mapping relationship table, and performs state management of user sessions on the 4G side and 5G side; the northbound SBI client module is an HTTP protocol client that realizes network element service discovery and selection.

[0012] The 5G core network element group (5GC NFs) includes 5G network elements that implement various specific functions, including Unified Data Management (UDM), Authentication Server Function (AUSF), Session Management Function (SMF), Policy Control Function (PCF), and User Plane Function (UPF).

[0013] The unified signaling processing method based on the aforementioned signaling proxy architecture for 4G and 5G converged core networks includes four parts: user authentication and subscription data acquisition, user location update, PDN connection / session establishment, and session release.

[0014] In the user authentication and contract data acquisition process, the Proxy receives the authentication information request from the MME, performs protocol conversion, and sends a request to the Authentication Server Function (AUSF) of 5GC NFs. The AUSF performs authentication and returns the result. The Proxy performs protocol conversion again and returns the authentication information response to the MME.

[0015] In the user location update process, the Proxy receives the location update request from the MME, performs protocol conversion, and sends a request to the Unified Data Management UDM of 5GC NFs. The UDM registers and acts as a proxy to obtain the user's subscription data. The Proxy then performs protocol conversion again and returns the location update response to the MME.

[0016] In the PDN connection / session establishment process, the Proxy receives the MME's request to create a session, creates a session context and assigns an ID, performs protocol conversion and sends a request to the 5GC NFs session management function SMF. The SMF processes the request and returns a creation response. The Proxy performs protocol conversion again and returns the session creation response to the MME.

[0017] In the session release process, the Proxy receives the session release request from the MME, queries the corresponding content ID and conversation ID, initiates a session release request to the 5GC NFs session management function SMF, the SMF executes the session release process and returns the result, the Proxy cleans up the local context and returns the session release response to the MME.

[0018] Compared with the prior art, the beneficial effects of the present invention include:

[0019] (1) Maintaining architectural purity:

[0020] This invention terminates the traditional 4G signaling protocol stack (Diameter, GTPv2-C / UDP) entirely on the Proxy through independently deployed converged proxy network elements. Service processing network elements within the 5GC (SMF, UDM, AUSF, PCF, etc.) do not require the introduction of any 4G protocol stack code, fully maintaining the purity and simplicity of the 5G Service Based Architecture (SBA). Each 5GC network element interacts only through the SBI interface of the standard HTTP / 2 protocol, conforming to the cloud-native design philosophy of the 3GPP 5G core network.

[0021] (2) Development and maintenance costs are significantly reduced:

[0022] The complexity of the traditional 4G protocol stack is encapsulated within the Proxy, eliminating the need for the 5GC network element development team to master the underlying communication protocol details such as Diameter protocol AVP encoding / decoding, GTPv2-C TEID management, and IE nested parsing. The 5GC network element only needs to handle standard or a few extended HTTP JSON fields, allowing for the reuse of mature Web microservice development frameworks and toolchains, significantly reducing the skill threshold and learning cost for developers. Furthermore, bug fixes and version upgrades of the 4G protocol stack only affect the Proxy network element, requiring no coordinated modifications to the 5GC network element, greatly improving maintenance efficiency.

[0023] (3) Cloud-native elastic scaling and zero-disruption migration:

[0024] This invention addresses the core contradiction of Diameter and GTPv2-C protocols, which rely on fixed IP communication, and their inability to scale elastically in cloud-native environments through stable virtual IP access and a stateless architecture. The proxy exposes a stable virtual IP through Kubernetes Service. The MME configures this virtual IP as the HSS and SGW address, ensuring it remains unchanged regardless of the addition or removal of backend proxy Pods, making it completely transparent to the MME. Simultaneously, the proxy employs a stateless architecture that separates compute and storage, externalizing all user session contexts to a distributed in-memory database cluster. Any proxy instance can handle signaling requests from any user. In scaling scenarios, new instances can handle new requests immediately upon startup, without preheating. In scaling-down scenarios, graceful shutdown is achieved through a drainage mechanism and the peer-to-peer disconnection process of the Diameter protocol. The MME automatically re-establishes connections to the virtual IP and routes the connection to a healthy instance. Session state is loaded from the distributed database on demand, achieving zero-disruption migration. The elastic scaling of 5GC internal network elements is entirely based on standard Kubernetes Pod horizontal automatic scaling of HPA, unconstrained by traditional telecommunications protocols. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of an existing network element embedded converged core network scheme in the background technology of this invention.

[0026] Figure 2 This is a schematic diagram of a signaling proxy architecture for a converged core network of 4G and 5G in a specific embodiment of the present invention.

[0027] Figure 3 This is a flowchart illustrating the steps of a unified signaling processing method for a signaling proxy architecture oriented towards a converged core network of 4G and 5G in a specific embodiment of the present invention. Detailed Implementation

[0028] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings.

[0029] A converged architecture for 4G and 5G core networks based on signaling brokers, referenced Figure 2 The architecture includes the following components:

[0030] (1) 4G Mobile Management Entity (MME): Responsible for the access management, mobility management and bearer management of 4G terminals. It interacts with HSS through the S6a interface to obtain subscription data and authentication vector, and interacts with SGW through the S11 interface to manage EPS bearer.

[0031] (2) Converged Proxy Network Element: This is the core innovative network element of this invention, independently deployed between the MME and 5GC, and has the following functional modules:

[0032] a. Southbound Protocol Adaptation Module:

[0033] Diameter protocol endpoint: Implements the Diameter basic protocol stack, Diameter peer connection management (CER / CEA capability exchange request / response messages, DWR / DWA watchdog heartbeat request / response messages), and S6a application layer message processing (AIR / AIA authentication information request / response messages, ULR / ULA location update request / response messages, PUR / PUA clear user request / response messages, IDR / IDA insert data request / response messages, CLR / CLA cancel location request / response messages, DSR / DSA delete subscription request / response messages, RSR / RSA reset request / response messages, NOR / NOA notification request / response messages, etc.). The Proxy presents itself to the MME as a standard HSS role.

[0034] GTPv2-C Protocol Endpoint: Implements the GTPv2-C protocol stack, including UDP transport layer, message encoding / decoding, TEID allocation and management, sequence number matching, Echo request / response heartbeat, path fault management, S11 interface message processing (Create Session Request / Response, Modify Bearer Request / Response, Delete Session Request / Response, Release Access Bearers Request / Response, Downlink DataNotification, etc.). The Proxy presents itself to the MME as a standard SGW-C role (and includes PGW-C functionality).

[0035] b. Protocol conversion engine:

[0036] 4G→5G forward conversion: After parsing and extracting the Diameter AVP / GTPv2 IE, it is converted into the JSON payload fields of the HTTP request according to the predefined mapping rule table; 5G→4G reverse conversion: The JSON payload fields of the HTTP response are encapsulated into Diameter AVP / GTPv2 IE according to the reverse mapping rule; Parameter mapping rule table: Defines the correspondence between 4G parameters and 5G parameters, including but not limited to International Mobile Subscriber Identity (IMSI) ↔ Subscription Permanent Identifier (SUPI), Access Point Name (APN) ↔ Data Network Name (DNN), Evolved Packet System Bearer Identifier (EBI) ↔ Protocol Data Unit (PDU) Session ID, Quality of Service Level Identifier (QCI) ↔ 5G Quality of Service Identifier (5QI), Access Point Name Aggregated Maximum Bit Rate (APN-AMBR) ↔ Session Aggregated Maximum Bit Rate (Session-AMBR), Tracking Area Identifier (TAI) ↔ Tracking Area Identifier (TAI), Evolved Universal Terrestrial Radio Access Network Cell Global Identifier (ECGI) ↔ New Radio Interface Cell Global Identifier (NCGI), etc.

[0037] c. Context Management Module:

[0038] EPS Session Context Cache: Stores each user's 4G-side session information using IMSI as the primary key, including MME F-TEID (Control Plane Tunnel Endpoint), EBI list, default bearer ID, etc.; Mapping Relationship Table: Maintains cross-generational identifier mapping relationships such as [EPS Bearer ID ↔ Protocol Data Unit Session ID] and [4G Tunnel Endpoint ID 4G TEID ↔ 5G Session Management Context ID 5G SM Context ID]; State Machine Management: Tracks the state of each user session on the 4G and 5G sides to ensure state consistency.

[0039] d. Northbound SBI client module:

[0040] A standard HTTP / 2 client supporting TLS 1.3 secure transmission; implements network element (NF) service discovery and selection (via network storage function (NRF) or static configuration); supports calling the UE context management service Nudm_UECM and subscribing to the data management service Nudm_SDM of the unified data management network element (UDM); supports calling the PDU session management service Nsmf_PDUSession of the session management function network element (SMF); and supports calling the UE authentication service Nausf_UEAuthentication of the authentication server function network element (AUSF) (when 5G-AKA authentication is required).

[0041] (3) 5G core network element group (5GC NFs): including but not limited to the following standard 5G network elements:

[0042] UDM (Unified Data Management): Unified data management provides services such as user subscription data query and authentication vector generation, and provides external services only through HTTP / SBI interfaces.

[0043] AUSF (Authentication Server Function): This authentication server function provides authentication services such as 5G-AKA only through the HTTP / SBI interface.

[0044] SMF (Session Management Function): This function is responsible for the establishment, modification, and release of PDU sessions. It interacts with the UPF through the PFCP protocol (N4 interface) to manage the user plane and provides session management services externally only through the HTTP / SBI interface.

[0045] PCF (Policy Control Function): This function provides SM policy association and AM policy association, and is only available to the outside world through the HTTP / SBI interface.

[0046] UPF (User Plane Function): The user plane function is responsible for GTP-U tunnel termination, packet forwarding, QoS enforcement, etc., and receives SMF forwarding rules through the PFCP protocol.

[0047] The above 5GC NFs do not require the introduction of any traditional 4G protocol stack (Diameter, GTPv2-C), thus maintaining the purity of the 5G SBA architecture.

[0048] The above architecture supports two interface expansion modes to minimize the cost of 5G network element upgrades:

[0049] (1) Reuse Mode: When the JSON fields of the native SBI interface of the 5G network element (SMF / UDM) are sufficient to accommodate the 4G context information, the Proxy directly maps the 4G parameters to the corresponding fields of the native 5G standard API. For example, the PDU session creation data PduSessionCreateData structure has defined EPS interoperability related fields such as epsBearerId, epsInterworkingInd, and ratType, which can be directly reused.

[0050] (2) Incremental Expansion Mode: For parameter fields that are unique to 4G and do not exist in the native 5G API, add a dedicated SBI interface to the existing HTTP microservice of SMF / UDM, for example:

[0051] - / nsmf-pdusession / v1 / eps-interworking / sessions

[0052] - / nudm-sdm / v2 / eps-subscription / location-update

[0053] 5G network elements only need to add JSON field parsing logic to the HTTP application layer, without needing to introduce the underlying protocol library of GTPv2-C or Diameter.

[0054] A unified signaling processing method for a 4G and 5G converged core network based on the above signaling proxy architecture includes the following processing flow:

[0055] (1) User authentication and contract data acquisition process:

[0056] Step S101: The Proxy's Diameter protocol endpoint receives the S6a Authentication Information Request (AIR) message sent by the MME and extracts the IMSI, Visited PLMN ID, number of authentication vectors requested, and other Diameter AVP information.

[0057] Step S102: The proxy's protocol conversion engine converts the IMSI to SUPI format (imsi-xxxxxxxxxxxxxxx), maps the Visited PLMN ID to Serving Network information, and assembles the request parameters into a JSON payload.

[0058] Step S103: The northbound SBI client of the Proxy sends an HTTP POST request (Nausf_UEAuthentication_Authenticate) to AUSF, carrying SUPI and Serving Network information.

[0059] Step S104: AUSF calls the UDM’s Nudm_UEAuthentication_Get service to obtain the authentication vector, executes the 5G-AKA or EAP-AKA authentication algorithm, and returns the authentication vector to the Proxy.

[0060] Step S105: The Proxy's protocol conversion engine maps the 5G authentication vector to the 4G E-UTRAN authentication vector format (RAND, AUTN, XRES, KASME), and encapsulates it as Diameter AVP.

[0061] Step S106: The Proxy's Diameter protocol endpoint returns an Authentication Information Answer (AIA) message to the MME.

[0062] (2) User location update process:

[0063] Step S201: The Proxy's Diameter protocol endpoint receives the S6a Update LocationRequest (ULR) message sent by the MME and extracts AVPs such as IMSI, MME Identity, and ULR-Flags.

[0064] Step S202: The Proxy's protocol conversion engine performs parameter mapping, converting the ULR parameters into an HTTP request.

[0065] Step S203: The Proxy sends a Nudm_UECM_Registration request (HTTP PUT) to the UDM to register the MME (through the Proxy) as the user's service AMF.

[0066] Step S204: The Proxy sends a Nudm_SDM_Get request (HTTPGET) to the UDM to obtain the user's subscription data, including Access and Mobility Subscription Data, Session Management Subscription Data, etc.

[0067] Step S205: UDM processes the HTTP request, queries the Unified Data Warehouse (UDR) to obtain the contract data, and returns the contract data in JSON format with an HTTP 200 OK response.

[0068] Step S206: The Proxy's protocol conversion engine reverse maps the JSON subscription data into 4G format user subscription data attribute value pairs (Subscription Data AVP), including APN Configuration Profile, Subscribed APN-AMBR, EPS Subscribed QoS Profile, etc.

[0069] Step S207: The Proxy returns an Update Location Answer (ULA) message to the MME.

[0070] (3) PDN connection / session establishment process:

[0071] Step S301: The Proxy's GTPv2-C protocol endpoint receives the Create Session Request message sent by the MME and parses the International Mobile Subscriber Identity (IMSI), Access Point Name (APN), Packet Data Network Type (PDN Type), Sender Fully Qualified Tunnel Endpoint Identifier (Sender F-TEID), Packet Data Network Bearer Context (including EBI), and other IEs.

[0072] Step S302: The Proxy's context management module creates an EPS session context, assigns a PDU Session ID, establishes an [EBI ↔ PDU Session ID] mapping, and records the MME F-TEID.

[0073] Step S303: The Proxy's protocol conversion engine maps the GTPv2 IE to a JSON payload (International Mobile Subscriber Identity IMSI ↔ Subscription Permanent Identifier SUPI, Access Point Name APN ↔ Data Network Name DNN, Evolved Packet System Bearer Identifier EBI ↔ Protocol Data Unit Session Identifier PDU Session ID, Quality of Service Level Identifier QCI in Bearer QoS ↔ 5G Quality of Service Identifier 5QI).

[0074] Step S304: The Proxy sends an HTTP POST request (Nsmf_PDUSession_CreateSMContext) to the SMF, carrying the JSON payload assembled in step S303.

[0075] Step S305: After receiving the HTTP request, SMF executes the following steps in sequence:

[0076] a) Query session management subscription data from UDM (Nudm_SDM_Get);

[0077] b) Establish SM policy association with PCF (Session Management Policy Association Creation Operation Npcf_SMPolicyControl_Create) to obtain PCC rules and QoS decisions;

[0078] c) Assign user IP addresses from the IP address pool;

[0079] d) Send a PFCP Session Establishment Request (N4 interface) to the UPF to establish user plane forwarding rules, including Packet Detection Rule (PDR), Forwarding Action Rule (FAR), QoS Enforcement Rule (QER), etc. The UPF returns the allocated user plane GTP-U forwarding tunnel endpoint identifier GTP-U F-TEID.

[0080] Step S306: SMF returns an HTTP 201 Created response to the Proxy, carrying JSON fields such as the assigned user IP address, UPF user plane F-TEID, QoS parameters, and EBI allocation result.

[0081] Step S307: The proxy's protocol conversion engine performs reverse mapping, converting the JSON fields in the HTTP response to GTPv2 IE (User IP → PAA, UPF F-TEID → PGW S5 / S8 User Plane F-TEID, QoS parameters → Bearer QoS, HTTP 201 → Cause: Request Accepted), and simultaneously filling in the proxy's own control plane F-TEID as the Sender F-TEID.

[0082] Step S308: The Proxy returns a Create Session Response message to the MME.

[0083] (4) Session release procedure:

[0084] Step S401: The Proxy's GTPv2-C protocol endpoint receives the Delete Session Request message sent by the MME and extracts the TEID and related IE.

[0085] Step S402: The Proxy looks up the corresponding 5G Session Management Context Identifier (5G SM Context ID) and PDU Session ID in the Context Management Module based on the TEID.

[0086] Step S403: The Proxy sends an HTTP POST request (Nsmf_PDUSession_ReleaseSMContext) to the SMF to release the PDU session.

[0087] Step S404: The SMF executes the session release procedure, sends a PFCP Session Deletion Request to the UPF to delete the user plane forwarding rule, sends an SM policy association termination request to the PCF, and returns an HTTP 200 OK response.

[0088] Step S405: The Proxy cleans up the local context and returns a Delete Session Response message to the MME.

[0089] Furthermore, this embodiment presents a scheme for elastic scaling of proxy network elements for cloud-native deployments. This scheme addresses the core issue that Diameter and GTPv2-C protocols, based on fixed IP communication, cannot elastically scale in cloud-native environments. It solves this problem by combining stable virtual IP access, a stateless architecture, and external state storage.

[0090] (1) Stable virtual IP access:

[0091] The proxy exposes a stable virtual IP (VIP) as its southbound access address through the Kubernetes Service. The MME configures this virtual IP as its HSS address (for S6a Diameter connections) and SGW address (for S11 GTPv2-C signaling). This virtual IP is maintained by the Kubernetes platform and does not change with the addition or removal of backend proxy pods, making it completely transparent to the MME. The Kubernetes Service distributes signaling traffic arriving at the virtual IP to each backend proxy pod through Layer 4 load balancing. During GTPv2-C protocol interactions, the proxy fills in this virtual IP, rather than the pod's own IP, in the control plane F-TEID (Fully Qualified Tunnel Endpoint Identifier) ​​of response messages such as Create Session Response, ensuring that subsequent GTPv2-C signaling messages sent by the MME are always routed through the virtual IP and do not depend on the IP address of any specific pod.

[0092] (2) Distributed external context storage:

[0093] All state data from the Proxy's internal context management module, including EPS session context, cross-generational identifier mapping tables ([EPS Bearer ID ↔ PDU Session ID], [4G TEID ↔ 5G SM Context ID], [Diameter Session-ID ↔ HTTP Transaction-ID]), and user session state machine information, are stripped from the Proxy process's local memory and persistently stored in a separately deployed distributed in-memory database cluster (such as RedisCluster). The Proxy instance itself is designed as a stateless node, reading and updating the context from the distributed storage as needed each time a signaling message is processed, without retaining any persistent state related to user sessions locally. Therefore, any ProxyPod can handle signaling requests from any user.

[0094] (3) Expansion process:

[0095] When the Kubernetes Pod Horizontal Pod Autoscaler (HPA) or the operations and maintenance system detects that the load on the proxy instance exceeds the threshold:

[0096] Step E101: Kubernetes starts a new Proxy Pod, which is automatically registered as a backend endpoint of the Kubernetes Service.

[0097] Step E102: The Kubernetes Service's load balancer begins distributing signaling requests for newly arriving virtual IPs to new Pods. The new Pods can process requests by reading the user context from the distributed in-memory database on demand, without the need for warm-up or state preloading, and are immediately ready to provide services.

[0098] (4) Volume reduction process:

[0099] When Kubernetes initiates Pod shrinking or eviction:

[0100] Step E201: Kubernetes sends a Pre-Stop Hook scaling-down pre-notification to the target Proxy Pod, and the Pod enters Drain mode, ceasing to accept new signaling requests;

[0101] Step E202: The Pod immediately flushes any incremental context data that has not yet been committed to the distributed in-memory database during the current processing cycle to ensure complete and persistent state.

[0102] Step E203: For Diameter connections, the Pod sends a Disconnect-Peer-Request (DPR) message to the MME through the Diameter protocol's standard disconnection procedure. The MME returns a Disconnect-Peer-Answer (DPA) response and gracefully closes the connection. The MME then automatically re-initiates a connection request to the configured HSS address (i.e., the virtual IP) according to the protocol specification. The Kubernetes Service routes this connection to a healthy ProxyPod. After the new Pod completes the CER / CEA (Capabilities-Exchange-Request / Answer) capability exchange, it can continue to provide services. For GTPv2-C signaling, since GTPv2-C is based on the UDP connectionless protocol, after the Kubernetes Service removes the Pod from the backend endpoint list, subsequent GTPv2-C requests arriving at the virtual IP are automatically routed to the healthy Pod.

[0103] Step E204: Healthy Pods directly load user context information from the distributed in-memory database on demand, without needing to re-trigger the 4G side attach process or the 5G side PDU session reconstruction, achieving zero-interruption session migration.

[0104] (5) Extended applications of MME expansion and contraction:

[0105] The aforementioned virtual IP access solution can also be extended to the elastic scaling of MMEs. The eNodeB configures the virtual IP of the MME as its S1-MME interface address, and multiple MME instances share the same virtual IP. Load balancing is achieved through Kubernetes Service, and the addition or removal of MMEs is transparent to the eNodeB.

[0106] This embodiment presents an innovative independent signaling proxy architecture for 4G and 5G convergence, breaking away from the cumbersome design of existing "embedded convergence within network elements." It pioneeringly introduces an independent "converged proxy network element" between the 4G MME and the 5G core network. This architecture uniformly terminates the traditional 4G communication underlying protocol stack (Diameter, GTPv2-C, etc.) in the southbound direction of the proxy network element, while interacting with the 5GC as a standard SBI client in the northbound direction. This architecture isolates complexity, frees up the 5GC, and ensures the absolute purity of the 5G core network SBA service architecture.

[0107] This embodiment presents a unified method for cross-generational signaling protocol conversion and context state management, proposing an efficient signaling processing mechanism. The core of this mechanism lies in the "protocol conversion engine" and "context management module" within the agent network element. It achieves bidirectional, precise parsing and parameter mapping (such as IMSI↔SUPI, EBI↔PDU Session ID, etc.) between traditional Diameter AVP / GTPv2 IE and 5G HTTP / JSON payloads. Simultaneously, this method independently maintains cross-generational identifier mapping and state machines on the agent side, enabling seamless compatibility with 4G terminal access, authentication, and session management processes without modifying the 5GC network element.

[0108] This embodiment presents an efficient and lightweight 5G interface evolution and extension mechanism. Addressing the issue of transparent transmission of 4G-specific parameters, it proposes an interface extension strategy combining a "reuse mode" and an "incremental extension mode." 5G service processing network elements (such as SMF and UDM) do not need to introduce any traditional protocol libraries; they only need to add specific URI endpoints or expand JSON fields in the existing HTTP microservice application layer to complete 4G service adaptation. This lightweight interface extension method significantly reduces the R&D threshold, development cycle, and subsequent maintenance costs of core network convergence evolution.

[0109] This embodiment presents a mechanism for elastic scaling of proxy network elements for cloud-native deployments. Addressing the core pain point that Diameter and GTPv2-C protocols, based on a fixed IP peer-to-peer communication model, cannot elastically scale in cloud-native environments, this is resolved through stable virtual IP access and a stateless architecture design. The proxy exposes a stable virtual IP through a Kubernetes Service, eliminating the constraints of fixed IP communication at the access layer, enabling the proxy to possess cloud-native elastic scaling capabilities consistent with 5GC HTTP microservices. Simultaneously, all user session contexts are externalized to a distributed in-memory database cluster. The proxy instance itself is stateless; new instances are immediately available during scaling up, and during scaling down, a drainage mechanism disconnects the proxy from Diameter DPR / DPA, achieving zero-disruption session migration.

[0110] The solution provided by this patent can reuse the original 5G SBI interface, centralize the traditional 4G protocol stack to the proxy network element, and further propose virtual IP (VIP) access and a stateless design that separates computing and storage, so as to make full use of the automated operation and maintenance and elasticity capabilities of cloud-native platforms (such as Kubernetes, K8s), with reasonable logic and closed loop.

[0111] The above description is only a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. Any equivalent modifications or changes made by those skilled in the art based on the content disclosed in the present invention should be included within the scope of protection set forth in the claims.

Claims

1. A signaling proxy architecture for 4G and 5G converged core networks, characterized in that: The architecture includes a 4G Mobile Management Entity (MME), a converged proxy network element (Proxy), and a 5G core network element group (5GC NFs); among which... The 4G Mobile Management Entity (MME) is responsible for the access management, mobility management, and bearer management of 4G terminals. It interacts with the Home Subscriber Server (HSS) to obtain subscription data and authentication vectors, and interacts with the Serving Gateway (SGW) to manage the Evolved Packet System (EPS) bearer. The integrated proxy network element is independently deployed between the MME and the 5G core network element group 5GC NFs, including a southbound protocol adaptation module, a protocol conversion engine, a context management module, and a northbound service interface SBI client module. The southbound protocol adaptation module includes Diameter protocol endpoints and GTPv2-C protocol endpoints to implement the Diameter basic protocol stack and GTPv2-C protocol stack; the protocol conversion engine implements 4G→5G forward conversion and 5G→4G reverse conversion, and saves the parameter mapping rule table between 4G parameters and 5G parameters; the context management module includes EPS session context cache and mapping relationship table, and performs state management of user sessions on the 4G side and 5G side; the northbound SBI client module is an HTTP protocol client that realizes network element service discovery and selection. The architecture supports two interface extension modes: In reuse mode, when the JSON fields of the native SBI interface of the 5G network element are sufficient, the Proxy directly maps the 4G parameters to the corresponding fields of the native 5G standard API; In incremental extension mode, for parameter fields that are unique to 4G and do not exist in the native 5G API, a dedicated SBI interface is added to the existing HTTP microservice of the session management function SMF / unified data management UDM, and the 5G network element sets the parsing logic of the JSON fields at the HTTP application layer. The 5G core network element group (5GC NFs) includes 5G network elements that implement various specific functions, including Unified Data Management (UDM), Authentication Server Function (AUSF), Session Management Function (SMF), Policy Control Function (PCF), and User Plane Function (UPF).

2. The signaling proxy architecture for a converged 4G and 5G core network according to claim 1, characterized in that: In the southbound protocol adaptation module, the Diameter protocol endpoint implements the Diameter basic protocol stack, including Diameter peer connection management and S6a application layer message processing. The Proxy presents itself to the MME as a standard Home Subscriber Server (HSS) role. The GTPv2-C protocol endpoint implements the GTPv2-C protocol stack, including the User Datagram Protocol (UDP) transport layer, message encoding and decoding, Tunnel Endpoint Identifier (TEID) allocation and management, sequence number matching, Echo request / response heartbeat, path fault management, and S11 interface message processing. The Proxy presents itself to the MME as a standard Service Gateway Control Plane (SGW-C) role and includes Packet Data Gateway Control Plane (PGW-C) functionality.

3. The signaling proxy architecture for a converged 4G and 5G core network according to claim 1, characterized in that: In the protocol conversion engine, the 4G→5G forward conversion involves parsing and extracting the Diameter AVP / GTPv2 IE and converting it into the JSON payload fields of an HTTP request according to a predefined parameter mapping rule table. The 5G→4G reverse conversion involves encapsulating the JSON payload fields of the HTTP response into Diameter attribute value pairs AVP / GTPv2 IE according to the parameter mapping rule table. The parameter mapping rule table defines the correspondence between 4G parameters and 5G parameters, including International Mobile Subscriber Identity (IMSI) ↔ Subscription Permanent Identifier (SUPI), Access Point Name (APN) ↔ Data Network Name (DNN), Evolved Packet System Bearer Identifier (EBI) ↔ Protocol Data Unit (PDU) Session ID, Quality of Service Level Identifier (QCI) ↔ 5G Quality of Service Identifier (5QI), Access Point Name Aggregated Maximum Bit Rate (APN-AMBR) ↔ Session Aggregated Maximum Bit Rate (Session-AMBR), Tracking Area Identifier (TAI) ↔ Tracking Area Identifier (TAI), Evolved Universal Terrestrial Radio Access Network Cell Global Identifier (ECGI) ↔ New Radio Cell Global Identifier (NCGI).

4. The signaling proxy architecture for a converged core network of 4G and 5G as described in claim 1, characterized in that: In the context management module, the EPS session context cache uses IMSI as the primary key to store each user's 4G-side session information, including the 4G mobility management entity's control plane tunnel endpoint identifier MME F-TEID, EBI list, and default bearer ID. The mapping table maintains the cross-generational identifier mapping relationship between [EPS Bearer ID ↔ Protocol Data Unit Session ID] and [4G Tunnel Endpoint ID 4G TEID ↔ 5G Session Management Context ID 5G SM Context ID]. A state machine manages and tracks the state of each user session on both the 4G and 5G sides to ensure state consistency. All the above state data is persistently stored in an independently deployed distributed in-memory database cluster. Each time a signaling message is processed, the context is read from the distributed storage and updated on demand. No persistent state related to the user session is retained locally, making the Proxy instance a stateless node, allowing any instance to handle signaling requests from any user.

5. The signaling proxy architecture for a converged core network of 4G and 5G as described in claim 1, characterized in that: The northbound SBI client module is a standard HTTP / 2 client that supports TLS 1.3 secure transmission, enabling network element (NF) service discovery and selection through network storage function (NRF) or static configuration; it supports calling the UE context management service Nudm_UECM and subscribing to the data management service Nudm_SDM of the unified data management network element (UDM). Supports calling the PDU session management service Nsmf_PDUSession of the SMF (Session Management Function) network element; It supports calling the UE authentication service Nausf_UEAuthentication of the AUSF network element, which is a functional network element for the authentication server.

6. A unified signaling processing method based on the signaling proxy architecture for 4G and 5G converged core networks as described in any one of claims 1-5, characterized in that: The method comprises four parts: user authentication and subscription data acquisition, user location update, PDN connection / session establishment, and session release; among which, In the user authentication and contract data acquisition process, the Proxy receives the authentication information request from the MME, performs protocol conversion, and sends a request to the Authentication Server Function (AUSF) of 5GC NFs. The AUSF performs authentication and returns the result. The Proxy performs protocol conversion again and returns the authentication information response to the MME. In the user location update process, the Proxy receives the location update request from the MME, performs protocol conversion, and sends a request to the Unified Data Management UDM of 5GC NFs. The UDM registers and acts as a proxy to obtain the user's subscription data. The Proxy then performs protocol conversion again and returns the location update response to the MME. In the PDN connection / session establishment process, the Proxy receives the MME's session creation request, creates a session context and assigns an ID, performs protocol conversion and sends a request to the 5GC NFs session management function SMF. The SMF processes the request and returns a creation response. The Proxy performs protocol conversion again and returns the session creation response to the MME. In the session release process, the Proxy receives the session release request from the MME, queries the corresponding content ID and conversation ID, initiates a session release request to the 5GCNFs session management function SMF, the SMF executes the session release process and returns the result, the Proxy cleans up the local context and returns the session release response to the MME. In the above process, the Proxy exposes a stable virtual IP as a southbound access address through the Kubernetes Service. The MME configures this virtual IP as the HSS address and SGW address. This virtual IP does not change with the addition or removal of the Proxy Pod instance running the converged proxy service. The Proxy fills the virtual IP instead of the Pod's own IP into the Control Plane Tunnel Endpoint Identifier F-TEID in the GTPv2-C response message. All user session contexts of the Proxy are externalized to the distributed in-memory database cluster. The Proxy instance itself is a stateless node, and any instance can handle signaling requests from any user. In the above process, when the Proxy instance is scaled up, the new Pod automatically registers as a backend endpoint of the Kubernetes Service after startup. The load balancer distributes new signaling requests to the new Pod, and the new Pod can handle the request by reading the user context from the distributed in-memory database on demand, without the need for warm-up. When the Proxy instance is scaled down, Kubernetes sends a scaling-down pre-notification to the target Pod. The Pod enters drainage mode and stops accepting new requests. Uncommitted context incremental data is forcibly flushed into the distributed in-memory database. The peering connection with the MME is gracefully closed through the DPR / DPA disconnection process of the Diameter protocol. The MME automatically re-establishes a connection to the virtual IP and is routed to the healthy Pod. The healthy Pod loads the user context from the distributed in-memory database on demand, without the need to re-trigger the 4G side attach process or the 5G side PDU session reconstruction, achieving zero-interruption migration of the session.

7. A unified signaling processing method for a converged core network of 4G and 5G as described in claim 6, characterized in that: The specific steps of the user authentication and contract data acquisition process are as follows: Step S101: The Proxy's Diameter protocol endpoint receives the S6a Authentication Information Request AIR message sent by the MME, and extracts the International Mobile Subscriber Identity (IMSI), the Visited PLMN ID, and the Diameter attribute value of the requested authentication vector number to the AVP. Step S102: The proxy's protocol conversion engine converts the IMSI to SUPI format imsi-, maps the Visited PLMN ID to Serving Network information, and assembles the request parameters into a JSON payload; Step S103: The northbound SBI client of the Proxy sends an HTTP POST request Nausf_UEAuthentication_Authenticate to AUSF, carrying SUPI format imsi- and Serving Network information; Step S104: AUSF calls the UDM's User Equipment Authentication Information Acquisition Service Nudm_UEAuthentication_Get to obtain the authentication vector, executes the authentication algorithm, and returns the authentication vector to the Proxy; Step S105: The Proxy's protocol conversion engine maps the 5G authentication vector to the 4G E-UTRAN authentication vector format and encapsulates it as Diameter AVP; Step S106: The Proxy's Diameter protocol endpoint returns an authentication information response AIA message to the MME.

8. A unified signaling processing method for a converged core network of 4G and 5G as described in claim 6, characterized in that: The specific steps of the user location update process are as follows: Step S201: The Proxy's Diameter protocol endpoint receives the S6a Location Update Request (ULR) message sent by the MME, and extracts the IMSI, MME Identity, and AVP of the Location Update Request field ULR-Flags. Step S202: The Proxy's protocol conversion engine performs parameter mapping, converting the URL parameters into an HTTP request; Step S203: The Proxy initiates a Nudm_UECM_Registration request to the UDM to obtain user equipment authentication information, mapping the MME to the Logical Access and Mobility Management Function (AMF) that serves the user through the Proxy. Step S204: The Proxy initiates a Nudm_SDM_Get request to the UDM subscription data management service to obtain the user's subscription data; Step S205: UDM processes the HTTP request, queries the Unified Data Warehouse (UDR) to obtain the contract data, and returns the contract data in JSON format with an HTTP 200 OK response; Step S206: The Proxy's protocol conversion engine reverse maps the JSON subscription data into 4G format Subscription Data AVP; Step S207: The Proxy returns an updated location response ULA message to the MME.

9. A unified signaling processing method for a converged core network of 4G and 5G as described in claim 6, characterized in that: The specific steps of the PDN connection / session establishment process are as follows: Step S301: The Proxy's GTPv2-C protocol endpoint receives the Create Session Request message sent by the MME, and parses the International Mobile Subscriber Identity (IMSI), Access Point Name (APN), Packet Data Network Type (PDN Type), Sender Fully Qualified Tunnel Endpoint Identifier (Sender F-TEID), and Packet Data Network Bearer Context (IE) information elements. Step S302: The Proxy's context management module creates an EPS session context, assigns a PDU Session ID, establishes a [EBI ↔ PDU Session ID] mapping, and records the MME F-TEID; Step S303: The Proxy's protocol conversion engine maps the GTPv2 IE to a JSON payload and sets the Evolved Packet System EPS Interworking Indicator epsInterworkingInd identifier; Step S304: The Proxy sends an HTTP POST request to the SMF to create an SM context, Nsmf_PDUSession_CreateSMContext, carrying the JSON payload assembled in step S303; Step S305: After receiving the HTTP request, SMF executes the following steps in sequence: a) Query session management subscription data Nudm_SDM_Get from UDM; b) Establish an SM policy association with PCF using Npcf_SMPolicyControl_Create to obtain PCC rules and QoS decisions; c) Assign user IP addresses from the IP address pool; d) Send a Packet Forwarding Control Protocol Session Establishment Request (PFCP) to the UPF to establish user plane forwarding rules, including Packet Inspection Rules (PDR), Forwarding Operation Rules (FAR), and QoS Enforcement Rules (QER). The UPF returns the assigned user plane GTP-U forwarding tunnel endpoint identifier (GTP-U F-TEID). Step S306: SMF returns an HTTP 201 Created response to the Proxy, carrying the assigned user IP address, UPF user plane F-TEID, QoS parameters, and JSON fields of the EBI allocation result; Step S307: The Proxy's protocol conversion engine performs reverse mapping, converting the JSON fields in the HTTP response to GTPv2 IE, and simultaneously filling in the Proxy's own control plane F-TEID as the Sender F-TEID; Step S308: The Proxy returns a session creation response message to the MME.

10. A unified signaling processing method for a converged core network of 4G and 5G as described in claim 6, characterized in that: The specific steps of the session release process are as follows: Step S401: The Proxy's GTPv2-C protocol endpoint receives the session release request message sent by the MME and extracts the TEID and related information element IE; Step S402: The Proxy looks up the corresponding Session Management Context ID (SM Context ID) and Protocol Data Unit Session ID (PDU Session ID) in the Context Management module based on the Tunnel Endpoint Identifier (TEID); Step S403: The Proxy sends an HTTP POST request Nsmf_PDUSession_ReleaseSMContext to the SMF, requesting the release of the PDU session; Step S404: SMF executes the session release procedure, sends a PFCP Session Deletion Request to UPF to delete the user plane forwarding rule, sends an SM policy association termination request to PCF, and returns HTTP 200 OK; Step S405: The Proxy cleans up the local context and returns a release session response message to the MME.

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