Relay UE and Remote UE Authorization via Offline Signed Tokens
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Solution Overview
Problem
Existing solutions for determining UE authorization to provide or utilize a relay service rely on network involvement, which fails when the UE is out of coverage and do not consider UE-to-UE relay scenarios.
Innovation Solution
Implementing verifiable authorization tokens with digital signatures for UEs to independently authenticate each other's authorization status, allowing UEs to determine whether they can provide or utilize relay services without network intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If network involvement is used for authorization verification, then authorization reliability is improved, but network coverage dependency increases and signaling load increases
Solution Approach 1:
The authorization token is generated and signed by the network function in advance, before the actual relay service usage. This preliminary authorization allows the UE to verify authorization status independently without real-time network involvement, enabling out of coverage operation while maintaining authorization reliability through pre-validated credentials
Solution Approach 2:
The authorization token acts as an intermediary credential between the network function and the UE. It carries the authorization information and digital signature that enables the UE to verify authorization status without direct network involvement, resolving the contradiction between reliable verification and out of coverage capability
2Reliability
If network involvement is used for authorization verification, then authorization control is improved, but signaling load increases
Solution Approach 1:
The authorization verification function is extracted from the network and embedded in the UE through the authorization token and digital signature. The UE can independently verify authorization status using the pre-generated token, eliminating the need for continuous network involvement and reducing signaling load while maintaining authorization control
Solution Approach 2:
The UE performs self-verification of authorization status using the authorization token and digital signature locally stored in the device. This self-service approach eliminates the need for network-based verification signaling, reducing signaling load while maintaining reliable authorization control through cryptographic validation
Data Source
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AI summary
A method performed by a relay UE for determining whether the relay UE may provide a relay service to a remote UE. The method includes the relay UE receiving from the remote UE a first message comprising a first authorization token and a first digital signature for verifying the authenticity of the first authorization token, wherein the first digital signature was generated by a first network function using the first authorization token and a first key, and the first authorization token indicates whether or not the remote UE is authorized to utilize a relay service provided by the relay UE. The method further includes the relay UE verifying the authenticity of the first authorization token.