PC5 Relay Link Identifier Isolation for Multi-Hop WTRU Updates
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Solution Overview
Problem
Existing mobile communication technologies face challenges in managing end-to-end link identifications (IDs) across multiple hops without impacting other links, particularly in relay scenarios, leading to inefficiencies in link identifier updates and security ID/session key management.
Innovation Solution
Implementing a relay WTRU that allocates R-specific security IDs/session key identifiers, adds per-hop IDs and E2E IDs to link identifier update messages, and includes or excludes adaptation headers based on message types to facilitate efficient end-to-end link establishment and management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If end-to-end link identifiers and security keys are managed across multiple hops in relay-based communication, then communication connectivity is established, but linkability issues occur and signaling storms increase during identifier updates
Solution Approach 1:
The patent segments end-to-end link identifiers into per-hop identifiers that are isolated at each relay hop. Instead of using a single end-to-end identifier across multiple hops, each hop uses its own local identifier (e.g., L2 ID, L3 ID) that is independent of other hops. This segmentation prevents linkability because observers cannot trace communications across hops using consistent identifiers, and reduces signaling storms because identifier updates are localized to individual hops rather than requiring coordination across the entire end-to-end path.
Solution Approach 2:
The relay WTRU acts as an intermediary that translates between end-to-end identifiers and per-hop identifiers. The relay receives messages with end-to-end identifiers from peer WTRUs and replaces them with relay-specific per-hop identifiers for forwarding. This intermediary function decouples the identifier spaces of different hops, preventing direct correlation between identifiers at different points in the communication path and eliminating the need for coordinated identifier updates across multiple hops.
2Stability of the object's composition
If link identifier update messages are propagated across all hops, then identifier consistency is maintained, but signaling storms occur during updates
Solution Approach 1:
The patent divides identifier management into independent per-hop segments rather than a unified end-to-end system. Each hop maintains its own identifier consistency independently through local update procedures. When an identifier needs to be updated, only the specific hop performing the update modifies its local identifiers, and this change is not propagated to other hops. This segmented approach maintains sufficient consistency for each hop's operations while avoiding the signaling storms that would result from coordinating updates across the entire multi-hop path.
Solution Approach 2:
The patent applies local quality by allowing each hop to have its own identifier update policies and procedures independent of other hops. Each relay WTRU can update its per-hop identifiers based on local conditions and requirements without being constrained by or needing to coordinate with identifier updates at other hops. This local autonomy eliminates the need for network-wide synchronization of identifier updates, thereby preventing signaling storms while maintaining operational consistency at each local hop.
3Stability of the object's composition
If peer WTRUs are involved in identifier update procedures across multiple hops, then end-to-end consistency is achieved, but communication overhead and signaling storms increase
Solution Approach 1:
The relay WTRU serves as an intermediary that handles identifier translation and update coordination, eliminating the need for peer WTRUs to be directly involved in each other's identifier update procedures. When a relay needs to update its per-hop identifiers, it does so independently and updates only its local mapping tables. The relay continues to translate between end-to-end identifiers from peer WTRUs and its own per-hop identifiers without requiring peer WTRUs to awareness or participation in the update process. This intermediary approach maintains functional end-to-end consistency while dramatically reducing signaling overhead compared to approaches requiring peer involvement.
Solution Approach 2:
The patent extracts the identifier update function from the peer WTRU interaction and relocates it to the relay WTRU. Instead of requiring peer WTRUs to exchange update messages and coordinate changes, the relay independently manages its own identifier updates by extracting and processing only the necessary end-to-end identifier information from incoming messages. This extraction of the update function from peer interactions and concentration at the relay eliminates unnecessary signaling while maintaining the ability to translate and forward identifiers correctly.
Data Source
AI summary
In examples, the E2E link IDs may be isolated per-hop, so that changes of link IDs may not impact other E2E/per-hop links (e.g., a LIU procedure may only run between a WTRU and the relay). A relay may allocate R-specific security IDs/session key identifiers (e.g., MSBs/LSBs of Knrp-sess ID). The relay (e.g., relay WTRU) may replace the security IDs/session key identifiers received from peer WTRUs with R-specific security IDs/session key identifiers, for example, if forwarding a message. In examples, per-hop IDs and E2E IDs may be added to link identifier update messages. In examples, the support application layer ID and IP address/prefix may be changed using a link modification procedure (e.g., between E2E peer WTRUs), which may be executed during the LIU procedure run between a WTRU and a WTRU-to-WTRU relay.