Radio Link Failure Recovery via Context Pre-allocation
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Solution Overview
Problem
In wireless communications networks, particularly in E-UTRAN, radio link failures (RLF) lead to time-consuming recovery processes as user equipment (UE) often need to transition through an idle state, which is inefficient, especially during handover under fading channel conditions.
Innovation Solution
Designating multiple network nodes as candidates to recognize and prepare for UE context information without reserving resources, allowing seamless handover and reducing the need for UE to enter an idle state, thereby expediting radio link recovery by pre-allocating resources only to the most likely target node.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If multiple eNBs are prepared using handover procedure to recognize UE context, then UE can recover from RLF without going via RRC_IDLE state, but network resources are reserved unnecessarily at multiple eNBs
Solution Approach 1:
The patent applies local quality by differentiating the treatment of different target eNBs: the most likely target eNB receives full context information and resource reservation, while other potential target eNBs receive only partial context information without resource reservation. This selective approach optimizes resource usage while maintaining fast recovery capability for the most probable scenario.
Solution Approach 2:
The patent implements preliminary action by pre-transmitting UE context information to multiple potential target eNBs before handover execution. This allows the UE to be quickly recognized upon RLF without entering idle state, while the resource reservation is only activated for the most likely target eNB based on prediction algorithms.
2Reliability
If UE enters RRC_IDLE state during RLF, then connection can be reestablished, but recovery process becomes time-consuming
Solution Approach 1:
The patent applies preliminary action by pre-distributing UE context information to multiple potential target eNBs before RLF occurs. When RLF happens, the UE can immediately reconnect to a prepared eNB without transitioning through RRC_IDLE state, significantly reducing recovery time while maintaining reliable connection reestablishment.
3Speed
If resources are reserved at multiple eNBs for UE, then UE can quickly reconnect after RLF, but network resource efficiency decreases
Solution Approach 1:
The patent implements local quality by applying different resource reservation strategies to different target eNBs based on their likelihood of being the actual handover target. The most likely target eNB receives full resource reservation for immediate reconnection, while other eNBs receive only contextual information without resource reservation, thereby maintaining fast reconnection speed while improving overall network resource efficiency.
Data Source
Figure 1~2
AI summary
In a wireless network, for example, an LTE network, the context information relating to a mobile terminal UE is transmitted to a plurality of network nodes eNB 2, 3 and 4 from a source network node, eNB 1. One of the eNB 2 is a handover target node and also reserves resources for the UE in anticipation of receiving it after handover. The other eNBs 3 and 4 do not reserve resources. In the event of radio link failure, the UE may attach to one of the designated eNBs3 and 4 that have not reserved resources, but that do recognize the UE because they have received its context. The method reduces the likelihood of the UE needing to go via the time consuming IDLE state while only reserving resources at a handover target eNB.