# US 12,114,223 B2 · Handovers between 5G radio access networks and IPV4 public data network sessions > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,114,223 B2 - Document ID: US12114223B2 - Status: Granted - Kind: B2 - Application number: 18/500,054 - Filed: 2023-11-01 - Published: 2024-02-22 - Granted: 2024-10-08 - Earliest claimed: 2022-02-24 - Assignees: T-Mobile USA, Inc. - Applicants: T-Mobile USA, Inc. - Inventors: Romil Kumar Sood; Kunal Prakash Barawkar - Web page: https://patentgrep.com/patent/US12114223B2 ## CPC - H04W 36/32: by location or mobility data, e.g. speed data - H04W 36/0022: {for transferring data sessions between adjacent core network technologies} - H04W 36/0033: {with transfer of context information} - H04W 8/26: Network addressing or numbering for mobility support - H04W 36/144: {over a different radio air interface technology} - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract To facilitate a handover of mobile devices from 5th Generation New Radio (5G) networks to 4th Generation (4G) networks, an accessibility and mobility management function (AMF) of the 5G network core inactivates a data session in which the mobile device is assigned an Internet protocol version 6 (IPv6) address when the mobile device is to be assigned an IP version 4 (IPv4) address in the 4G network. The AMF generates a modified context of the mobile device that omits the IPv6 address of the device. The inactivation of the IPv6 session causes the mobile device to initiate a new data session with the 4G core network, in which the device will be assigned an IPv4 address for use on the 4G network. The modified context is used by the 4G network to configure communications for the mobile device without interrupting network service to the mobile device. ## Claims ### Claim 1 A non-transitory computer-readable storage medium carrying instructions, which, when executed by at least one data processor of a system, cause the system to: receive a communication indicating a request by user equipment (UE) to transfer from: (i) a communication session with a gNodeB (gNB) associated with a 5th Generation New Radio (5G NR) telecommunications network in which the UE is assigned an Internet protocol version 6 (IPv6) address to enable communications by the UE in a packet data unit (PDU) session, to (ii) a communication session with an eNodeB (eNB) associated with a 4th Generation Long-Term Evolution (4G LTE) telecommunications network, in which the UE is assigned an Internet protocol version 4 (IPv4) address; transfer a context of the UE to a mobility management entity (MME) associated with the 4G LTE telecommunications network that does not include the IPv6 address assigned to the UE, wherein the context causes the MME to notify the UE that the IPv6 PDU session is inactive and to facilitate initiation of an IPv4 packet data network (PDN) session with a core network of the 4G LTE network; and release the IPv6 address assigned to the UE. ### Claim 2 (depends on 1) The non-transitory computer-readable storage medium of claim 1, wherein the 4G telecommunications network and the 5G telecommunications network are operated by a same network service provider. ### Claim 3 (depends on 1) The non-transitory computer-readable storage medium of claim 1, wherein the 4G telecommunications network is operated by a different network service provider than the 5G telecommunications network. ### Claim 4 (depends on 1) The non-transitory computer-readable storage medium of claim 1, wherein the context of the UE comprises one or more of: an international mobile subscriber identity (IMSI) assigned to the UE, an identity of a mobility management entity (MME) controlling a connection between the UE and the 4G LTE telecommunications network, security context of the UE, UE network capability, aggregate maximum bit rate (AMBR) configured for the UE, selected core network operator identifier, access point name (APN) restriction value indicative of a type of application data the UE is configured to send, or an evolved packet system (EPS) bearer context. ### Claim 5 (depends on 1) The non-transitory computer-readable storage medium of claim 1, wherein the gNB is a first gNB, and wherein the instructions when executed further cause the system to: receive a second communication indicating a request by the UE to transfer from: (i) the communication session with the first gNB, to (ii) a communication session with a second gNB associated with the 5G NR telecommunications network; and in response to the second communication, transfer a second context of the UE for use by the second gNB, wherein the second context includes the IPv6 address assigned to the UE. ### Claim 6 (depends on 1) The non-transitory computer-readable storage medium of claim 1, wherein the instructions when executed further cause the system to: receive a second communication indicating a request by a second UE to transfer from: (i) a communication session with the gNB, to (ii) a communication session with the eNB, in which the second UE is assigned an IPv6 address to enable communications by the second UE; and in response to the second communication, transfer a second context of the second UE for use by the eNB, wherein the second context includes the IPv6 address assigned to the second UE. ### Claim 7 (depends on 1) The non-transitory computer-readable storage medium of claim 1, wherein the communication is received from the MME, and wherein the UE is idle when the request to transfer is generated. ### Claim 8 (depends on 1) The non-transitory computer-readable storage medium of claim 1, wherein the communication is received from the gNB, and wherein the UE is operating in an active data session when the request to transfer is generated. ### Claim 9 (depends on 1) The non-transitory computer-readable storage medium of claim 1, wherein transferring the context of the UE to the MME comprises generating a relocation request that includes the context. ### Claim 10 A method comprising: receiving a communication indicating a request by a mobile device to transfer from a communication session with a gNodeB (gNB) associated with a 5th Generation New Radio (5G NR) telecommunications network to a communication session with an eNodeB (eNB) associated with a 4th Generation Long-Term Evolution (4G LTE) telecommunications network, wherein the mobile device is assigned an Internet protocol version 6 (IPv6) address to enable communications by the mobile device in a packet data unit (PDU) session within the 5G NR telecommunications network; in response to the received communication, transmit a request for context of the mobile device to an accessibility and mobility management function (AMF) associated with the 5G NR telecommunications network; configure the eNB using the context of the mobile device; and notify the mobile device that the PDU session associated with the IPv6 address has an inactive status, wherein the notification causes the mobile device to initiate an Internet protocol version 4 (IPv4) packet data network (PDN) session with a core network associated with the 4G LTE telecommunications network. ### Claim 11 (depends on 10) The method of claim 10, wherein the 4G telecommunications network and the 5G telecommunications network are operated by a same network service provider. ### Claim 12 (depends on 10) The method of claim 10, wherein the 4G telecommunications network is operated by a different network service provider than the 5G telecommunications network. ### Claim 13 (depends on 10) The method of claim 10, wherein the gNB is a first gNB, and wherein the method further comprises: receive a second communication indicating a request by the mobile device to transfer from: (i) the communication session with the first gNB, to (ii) a communication session with a second gNB associated with the 5G NR telecommunications network; and in response to the second communication, transfer a second context of the mobile device for use by the second gNB, wherein the second context includes the IPv6 address assigned to the mobile device. ### Claim 14 (depends on 10) The method of claim 10, further comprising: receive a second communication indicating a request by a second mobile device to transfer from: (i) a communication session with the gNB, to (ii) a communication session with the eNB, in which the second mobile device is assigned an IPv6 address to enable communications by the second mobile device; and in response to the second communication, transfer a second context of the second mobile device for use by the eNB, wherein the second context includes the IPv6 address assigned to the second mobile device. ### Claim 15 (depends on 10) The method of claim 10, wherein the communication is received from a mobility management entity (MME) associated with the 4G LTE telecommunications network, and wherein the mobile device is idle when the request to transfer is generated. ### Claim 16 (depends on 10) The method of claim 10, wherein the communication is received from the gNB, and wherein the mobile device is operating in an active data session when the request to transfer is generated. ### Claim 17 (depends on 10) The method of claim 10, wherein transferring the context of the mobile device to a mobility management entity (MME) associated with the 4G LTE telecommunications network comprises generating a relocation request that includes the context. ### Claim 18 A system comprising: at least one hardware processor; and at least one non-transitory memory storing instructions, which, when executed by the at least one hardware processor, cause the system to: receive a communication indicating a request by user equipment (UE) to transfer from a communication session with a gNodeB (gNB) associated with a 5th Generation New Radio (5G NR) telecommunications network to a communication session with an eNodeB (eNB) associated with a 4th Generation Long-Term Evolution (4G LTE) telecommunications network, wherein the UE is operating in an active data session when the request to transfer is received, and wherein the UE is assigned an Internet protocol version 6 (IPv6) address to enable communications by the UE in a packet data unit (PDU) session within the 5G NR telecommunications network; transmit to a mobility management entity (MME) associated with the 4G LTE telecommunications network, a relocation request associated with the UE that does not include the IPv6 address, the relocation request causing the MME to notify the UE that the IPv6 PDU session is inactive and to facilitate initiation of an IP version 4 (IPv4) packet data network (PDN) session with a core network of the 4G LTE telecommunications network; and release the IPv6 address assigned to the UE. ### Claim 19 (depends on 18) The system of claim 18, wherein the gNB is a first gNB, and wherein the instructions when executed further cause the system to: receive a second communication indicating a request by the UE to transfer from: (i) the communication session with the first gNB, to (ii) a communication session with a second gNB associated with the 5G NR telecommunications network; and in response to the second communication, transfer a second context of the UE for use by the second gNB, wherein the second context includes the IPv6 address assigned to the UE. ### Claim 20 (depends on 18) The system of claim 18, wherein the instructions when executed further cause the system to: receive a second communication indicating a request by a second UE to transfer from: (i) a communication session with the gNB, to (ii) a communication session with the eNB, in which the second UE is assigned an IPv6 address to enable communications by the second UE; and in response to the second communication, transfer a second context of the second UE for use by the eNB, wherein the second context includes the IPv6 address assigned to the second UE.