Direct-link establishment method, device and storage medium

{
  "publication_number": "US2026107336A1",
  "country": "US",
  "kind": "A1",
  "title": "Direct-link establishment method, device and storage medium",
  "abstract": "A method for establishing a direct link, including: transmitting a first message to third UE via second UE, where the first message is configured to request establishment of an end-to-end link, which is via the second UE, between the first UE and the third UE, and the second UE is a layer-2 relay UE; receiving a second message transmitted by the third UE via the second UE, where the second message is configured to request negotiation, of an end-to-end shared key shared by the first UE and the third UE, with the first UE; generating the end-to-end shared key by performing a security negotiation procedure with the third UE via the second UE; and receiving a third message transmitted by the third UE via the second UE, where the third message indicates completion of establishment of the end-to-end link.",
  "claims": [
    "1. A method for establishing a direct link, performed by first user equipment (UE), comprising: transmitting a first message to third UE via second UE, wherein the first message is configured to request establishment of an end-to-end link, which is via the second UE, between the first UE and the third UE, and the second UE is layer-2 relay UE; receiving a second message transmitted by the third UE via the second UE, wherein the second message is configured to request negotiation, of an end-to-end shared key shared by the first UE and the third UE, with the first UE; generating the end-to-end shared key by performing a security negotiation procedure with the third UE via the second UE; and receiving a third message transmitted by the third UE via the second UE, wherein the third message indicates completion of establishment of the end-to-end link. 2. The method according to claim 1, wherein the first message transmitted by the first UE to the second UE is encrypted with a first key, and the first key is generated through negotiation between the first UE and the second UE during establishment of a PC5 link between the first UE and the second UE and is shared by the first UE and the second UE. 3. The method according to claim 1, wherein the method further comprises at least one of: generating the end-to-end shared key by performing an Internet Key Exchange Vision2 (IKEv2) authentication procedure with the third UE via the second UE; encrypting the third message with the end-to-end shared key; or transmitting user identity (ID) information to the second UE, wherein the user ID information comprises at least one of a source UE identity, a relay UE identity, or a target UE identity. 4. (canceled) 5. The method according to claim 2, wherein the third message is encrypted with the end-to-end shared key and the first key. 6. (canceled) 7. A method for establishing a direct link, performed by third user equipment (UE), comprising: receiving a first message transmitted by first UE via second UE, wherein the first message is configured to request establishment of an end-to-end link, which is via the second UE, between the first UE and the third UE, and the second UE is layer-2 relay UE; transmitting a second message to the first UE via the second UE, wherein the second message is configured to request negotiation, of an end-to-end shared key shared by the first UE and the third UE, with the first UE; generating the end-to-end shared key by performing a security negotiation procedure with the first UE via the second UE; and transmitting a third message to the first UE via the second UE, wherein the third message indicates completion of establishment of the end-to-end link. 8. The method according to claim 7, wherein the first message received by the third UE from the second UE is encrypted with a second key, and the second key is generated through negotiation between the third UE and the second UE during establishment of a PC5 link between the third UE and the second UE and is shared by the third UE and the second UE. 9. The method according to claim 7, wherein the method further comprises at least one of: generating the end-to-end shared key by performing an Internet Key Exchange Vision2 (IKEv2) authentication procedure with the first UE via the second UE; encrypting the third message with the end-to-end shared key; or receiving user identity (ID) information transmitted by the second UE, wherein the user ID information comprises at least one of a source UE identity, a relay UE identity, or a target UE identity. 10. (canceled) 11. The method according to claim 8, wherein the third message is encrypted with the end-to-end shared key and the second key. 12. (canceled) 13. A method for establishing a direct link, performed by second user equipment (UE), comprising: receiving a first message transmitted by first UE, wherein the first message is configured to request establishment of an end-to-end link, which is via the second UE, between the first UE and third UE, and the second UE is layer-2 relay UE; transmitting the first message to the third UE; receiving a second message transmitted by the third UE, wherein the second message is configured to request negotiation, of an end-to-end shared key shared by the first UE and the third UE, with the first UE; transmitting the second message to the first UE, so as to facilitate generating the end-to-end shared key by performing a security negotiation procedure by the first UE and the third UE; receiving a third message transmitted by the third UE, wherein the third message indicates completion of establishment of the end-to-end link; and transmitting the third message to the first UE. 14. The method according to claim 13, wherein the first message received by the second UE from the first UE is encrypted with a first key, the first key is generated through negotiation between the first UE and the second UE during establishment of a PC5 link between the first UE and the second UE and is shared by the first UE and the second UE, and the method further comprises: decrypting, based on the first key, the first message received from the first UE. 15. The method according to claim 13, wherein the first message transmitted by the second UE to the third UE is encrypted with a second key, the second key is generated through negotiation between the third UE and the second UE during establishment of a PC5 link between the third UE and the second UE and is shared by the third UE and the second UE, and the method further comprises: encrypting, based on the second key, the first message obtained from the first UE. 16. The method according to claim 15, wherein the third message received by the second UE from the third UE is encrypted with the end-to-end shared key and the second key, and the method further comprises: decrypting, based on the second key, the third message received from the third UE. 17. The method according to claim 14, wherein the method further comprises encrypting, based on the first key, the third message obtained from the third UE, in a case where the third message transmitted by the second UE to the first UE is encrypted with the end-to-end shared key and the first key; or the method further comprises: transmitting a proximity service (ProSe) key request to a proximity key management function (PKMF) network element or a direct discovery name management function (DDNMF) network element of the second UE, wherein the ProSe key request comprises a credential ID and a relay service code (RSC)/ProSe code for requesting a long-term credential related to the credential ID and the RSC/ProSe code from the PKMF network element or the DDNMF network element, and the long-term credential is configured to generate the first key and a second key; and receiving a ProSe key response from the PKMF network element or the DDNMF network element, wherein the ProSe key response carries the long-term credential. 18 - 21. (canceled) 22. A communication device, comprising: a transceiver; a memory; and one or more processors collectively connected to the transceiver and the memory respectively, wherein the one or more processors are collectively configured to: control the transceiver to transceive radio signals, and cause the communication device to act as first user equipment (UE) and perform the method according to claim 1. 23. A system, comprising: a source user equipment (UE), a relay UE, and a target UE, wherein the source UE is configured to perform the method according to claim 1. 24. A non-transitory computer-readable storage medium, storing computer-executable instructions, wherein the computer-executable instructions when collectively executed by one or more processors of the first user equipment (UE) cause the first UE to execute the method according to claim 1. 25. A communication device, comprising: a transceiver; a memory; and one or more processors collectively connected to the transceiver and the memory respectively, wherein the one or more processors are collectively configured to: control the transceiver to transceive radio signals, and cause the communication device to act as third user equipment (UE) and perform the method according to claim 7. 26. A communication device, comprising: a transceiver; a memory; and one or more processors collectively connected to the transceiver and the memory respectively, wherein the one or more processors are collectively configured to: control the transceiver to transceive radio signals by executing computer-executable instructions on the memory, and cause the communication device to act as second user equipment (UE) and perform the method according to claim 13. 27. A non-transitory computer-readable storage medium, storing computer-executable instructions, wherein the computer-executable instructions when executed by one or more processors of third user equipment (UE) cause the third UE to perform the method according to claim 7. 28. A non-transitory computer-readable storage medium, storing computer-executable instructions, wherein the computer-executable instructions when executed by one or more processors of second user equipment (UE) cause the second UE to perform the method according to claim 13."
  ],
  "cpc": [
    "H04W 76/14",
    "H04W 12/03",
    "H04W 12/041",
    "H04W 88/04"
  ],
  "filing_date": "2022-09-29",
  "publication_date": "2026-04-16",
  "application_number": "US-202219116358-A"
}