Emergency Call Handling During LTE Connection Re-establishment
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Solution Overview
Problem
Emergency call handling is delayed during connection re-establishment procedures in LTE networks, as mobile terminals may wait for a predefined timer to expire before selecting a suitable cell, even if acceptable cells for emergency calls are available, and existing procedures fail to detect ongoing emergency calls during RRC connection re-establishment, leading to potential interruptions and failed reconnection attempts.
Innovation Solution
Implement a shorter cell selection timer for emergency calls during connection re-establishment, allowing immediate initiation of emergency calls without waiting for the longer timer to expire, and terminate ongoing connections or re-establishment procedures to prioritize emergency calls, using a cell selection process that considers cells acceptable for emergency calls but not necessarily suitable for regular connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mobile terminal waits for the predefined cell selection timer to expire during connection re-establishment, then the terminal can identify a suitable cell for regular connection, but emergency call establishment is delayed even when acceptable cells are available
Solution Approach 1:
The patent applies dynamics by making the cell selection timer value changeable based on the type of connection being established. The terminal dynamically selects between a first timer value for emergency calls and a second timer value for regular connections, allowing the system to adapt its behavior to the specific situation and prioritize emergency calls when needed.
Solution Approach 2:
The patent applies local quality by differentiating the cell selection process for emergency calls versus regular connections. The terminal uses different timer values and potentially different cell selection criteria depending on whether an emergency call is being initiated, allowing optimized behavior for each specific case rather than a uniform approach.
2Reliability
If the mobile terminal conducts RRC connection re-establishment procedure, then the connection can be recovered, but ongoing emergency calls may be interrupted due to undetected emergency call status
Solution Approach 1:
The patent applies feedback by implementing a mechanism where the terminal checks the emergency call status before initiating connection re-establishment. The re-establishment indication is evaluated in the context of existing emergency calls, and the re-establishment procedure is conditionally suppressed or modified based on this feedback, preventing harmful interruptions.
Solution Approach 2:
The patent applies preliminary anti-action by proactively preventing the connection re-establishment procedure from interfering with ongoing emergency calls. The terminal detects the emergency call status in advance and takes preventive action to avoid interrupting the emergency call, rather than allowing the interference to occur and then correcting it.
3Adaptability or versatility
If the mobile terminal selects from a wider number of cells for emergency calls, then emergency call accessibility is improved, but the terminal may select cells not suitable for regular connections causing re-establishment failures
Solution Approach 1:
The patent applies segmentation by separating the cell selection process into distinct modes: one for emergency calls with broader cell acceptance criteria, and another for regular connections with stricter suitability requirements. The terminal segments its cell selection behavior based on the connection type, allowing it to access emergency services from a wider range of cells while maintaining reliable re-establishment for regular connections.
Data Source
AI summary
Methods, apparatus and computer program products are provided in order to facilitate improved emergency call handling procedures and, in particular, to provide improved emergency call handling procedures relative to a connection re-establishment procedure. Emergency calls may therefore be handled in an efficient and expeditious fashion, even in instances in which a connection re-establishment procedure is ongoing at the time of the initiation of the emergency call or in instances in which a connection re-establishment procedure is commenced during an emergency call.