MAC-I Verification in RNAU Without Anchor Relocation
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Solution Overview
Problem
In radio resource control (RRC) inactive user equipment (UE), the failure to verify the resume message authentication code integrity (MAC-I) occurs due to the last serving gNB not being aware of the physical cell identifier (PCI) and cell radio network temporary identifier (C-RNTI) when the UE resumes on another gNB after a Radio Access Network (RAN) notification area update without anchor relocation, leading to unnecessary signaling and battery waste.
Innovation Solution
The implementation of an XnAP Retrieve UE Context Request message that carries the PCI and C-RNTI from the gNB on which the UE resumed, allowing the last serving gNB to verify the resumeMAC-I and prevent failure during the resumption process, especially in cases of RNAU without anchor relocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If RNAU without anchor relocation is used, then mobility and flexibility are improved, but MAC-I verification fails due to missing PCI and C-RNTI information
Solution Approach 1:
The patent applies preliminary action by having the gNB store and forward PCI and C-RNTI information in the UE context during the initial connection and RNAU procedures. This pre-stored information is then available when needed for MAC-I verification, preventing the verification failure that would otherwise occur in RNAU without anchor relocation scenarios.
Solution Approach 2:
The patent uses the UE context as an intermediary carrier that transports PCI and C-RNTI information between gNBs. When a UE moves between gNBs without anchor relocation, the new gNB can retrieve the stored PCI and C-RNTI from the UE context provided by the old gNB, enabling successful MAC-I verification without requiring the UE to maintain a direct connection to the original serving gNB.
2Reliability
If signaling is added to provide PCI and C-RNTI information, then MAC-I verification succeeds, but signaling overhead and battery consumption increase
Solution Approach 1:
The patent merges the transmission of PCI and C-RNTI information with existing UE context signaling messages. Instead of introducing separate dedicated signaling messages, the required information is embedded within the existing XnAP Retrieve UE Context Request/Response messages, thereby achieving reliable MAC-I verification without adding extra signaling overhead or increasing battery consumption.
3Reliability
If PCI and C-RNTI information is stored and forwarded, then MAC-I verification is enabled, but device complexity increases
Solution Approach 1:
The patent makes the UE context structure universal by enhancing it to carry multiple types of information including PCI, C-RNTI, and other UE parameters. This multi-functional UE context serves both as a storage mechanism for mobility management and as a verification credential for security purposes, thereby enabling MAC-I verification without requiring separate dedicated storage structures or increasing overall device complexity.
Data Source
AI summary
An apparatus of a next generation NodeB (gNB) comprises one or more baseband processors to process a radio resource control (RRC) resume request (RRCResumeRequest) from a user equipment (UE) in an inactive state (RRC_INACTIVE), and to send a UE context request (Retrieve UE Context Request) to a last serving gNB, wherein the UE context request includes a physical cell identifier (PCI) and cell radio network temporary identifier (C-RNTI) of the gNB. The apparatus can include a memory to store the RRC resume request at the gNB and the UE context request at the last serving gNB.