Mobile Relay Bearer Path Optimization for Latency Reduction
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Solution Overview
Problem
In next-generation LTE networks, mobile relay nodes (MRNs) deployed on vehicles face non-optimal routing issues due to lengthy bearer paths, leading to significant delays and potential connectivity problems when handovers occur, especially when MRNs traverse large distances or cross operator networks, resulting in subpar quality of service (QoS).
Innovation Solution
The implementation of path optimization techniques that allow for the direct re-routing of bearer paths from the core network to the target Donor Enhanced Base Station (DeNB) post-handover, using signaling mechanisms such as PGW relocation information elements and NAS activate default EPS bearer context requests to establish optimized bearer paths, bypassing the initial DeNB.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bearer paths are extended through both initial DeNB and target DeNB during handover, then connectivity is maintained during transition, but path length increases causing significant delays and subpar quality of service
Solution Approach 1:
The patent establishes an optimized bearer path from the core network directly to the target DeNB before the handover is complete. The path optimization is initiated during the handover process, allowing the system to prepare the shorter route in advance while maintaining connectivity through the initial DeNB, thus reducing latency without sacrificing reliability
Solution Approach 2:
The bearer path is made dynamic by allowing it to transition from a static route through the initial DeNB to an optimized route through the target DeNB. The system dynamically adjusts the bearer path based on handover status, switching from the longer path during transition to the shorter optimized path once handover is complete, thereby resolving the contradiction between maintaining connectivity and reducing latency
2Area of stationary object
If mobile relay nodes traverse large distances or cross operator networks, then coverage area is extended, but bearer path optimization becomes more complex and connectivity reliability decreases
Solution Approach 1:
The patent segments the bearer path into two distinct segments: a control plane segment that remains anchored at the initial DeNB for stability, and a user plane segment that is optimized to pass through the target DeNB for efficiency. This segmentation allows the system to extend coverage across large distances or operator networks while maintaining connectivity reliability by keeping the control anchor stable
3Loss of time
If bearer paths are optimized to pass directly through target DeNB, then latency is reduced and quality of service is improved, but handover complexity increases
Solution Approach 1:
The patent introduces the Mobility Management Entity (MME) as an intermediary that coordinates the bearer path optimization process. The MME manages the transition from the initial bearer path to the optimized bearer path, handling the signaling and coordination required for path optimization without requiring complex changes at the DeNB level, thus reducing handover complexity while achieving latency reduction
Data Source
AI summary
A bearer path can be optimized following a mobile relay node (MRN) handover in order to directly re-route the bearer path from a user equipment (UE) core network to a target donor base station (DeNB). Bearer path optimization signaling includes a packet data network gateway (PGW) relocation information element (IE) indicating that a PGW of an MRN is being relocated from an initial DeNB to a target DeNB. The PGW relocation IE may be carried in a path switch request message. Bearer path optimization signaling also includes an non-access stratum (NAS) activate default enhanced packet switch (EPS) bearer context request/accept messages for activating the optimized bearer path. The NAS activate default EPS bearer request/accept messages may be communicated between the mobile relay node mobility management entity (MME) and the MRN via the target DeNB.