Source eNB Ping Pong Reestablishment via Temporary Identity Mapping
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Solution Overview
Problem
In LTE wireless communication systems, the 'Too Early Handover' problem occurs when a UE loses connection during handover between eNBs, leading to failed reestablishment procedures due to incorrect configuration parameters, resulting in connection delays and data loss, especially as networks deploy more small cells and increase inter-eNB seams.
Innovation Solution
The solution involves the source eNB receiving a temporary identity from the target eNB during handover, using this identity to determine and authenticate the UE context, enabling successful RRC reestablishment across eNB seams by maintaining a mapping table for UE contexts and performing reestablishment procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the network deploys more small cells to increase capacity and coverage, then the network coverage and capacity are improved, but the inter-eNB seams increase causing more ping-pong handovers and reestablishment failures
Solution Approach 1:
The source eNB performs preliminary actions by storing the target eNB's C-RNTI in a lookup table during handover preparation. This preliminary storage enables the source eNB to quickly identify and retrieve the correct UE context when reestablishment is needed, preventing reestablishment failures without requiring additional real-time signaling or complex identification procedures during the actual reestablishment event.
2Ease of operation
If the UE uses the target eNB's C-RNTI during reestablishment to the source eNB, then the reestablishment procedure can be initiated, but the source eNB cannot locate the correct UE context causing reestablishment failure
Solution Approach 1:
The source eNB acts as an intermediary by maintaining a lookup table that maps target eNB C-RNTIs to corresponding UE contexts. This intermediary structure allows the source eNB to translate the temporary target C-RNTI into the correct UE context information, enabling successful reestablishment without requiring the UE to carry complex identification data or the source eNB to perform complex searches.
3Reliability
If the source eNB stores target C-RNTI mapping information in a lookup table, then UE context identification accuracy is improved, but the device complexity increases
Solution Approach 1:
The source eNB creates a simplified copy of the target eNB's identification information (C-RNTI) and stores it in a lookup table alongside the UE context. This copying approach allows the source eNB to use the target C-RNTI as a key to retrieve the correct UE context, providing accurate identification without requiring the source eNB to maintain complex mapping relationships or perform elaborate identification procedures.
Data Source
AI summary
A method to perform successful RRC reestablishment across eNB seams in ping pong scenarios without data loss is described. The method includes, during a handover procedure of a UE from a source AP to a target AP, receiving, at the source AP, a reestablishment request from the UE. The reestablishment request includes a temporary identity assigned by the target AP for the UE. The method also includes determining a UE context based on the temporary identity assigned by the target AP and performing a reestablishment procedure between the source AP and the UE. Apparatus and computer readable media are also described.