LTE Forward Handover Context Retrieval Mechanism
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Solution Overview
Problem
Current wireless communication systems, particularly LTE, face challenges in ensuring robust forward handovers and radio link failures, leading to service disruptions and data loss due to incomplete context retrieval and repeated connection attempts.
Innovation Solution
A method is introduced where a target base station receives identity information from a user terminal to initiate access, retrieves user context from the source base station, and sends a message to continue the handover without reperforming the Random Access Channel procedure, allowing for successful connection setup even in cases of radio link failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the user terminal performs a new RACH procedure after context retrieval failure, then the connection can be reestablished, but the handover reliability decreases and service disruption increases
Solution Approach 1:
The target base station performs preliminary retrieval of user context information from the source base station before completing the handover procedure. When context retrieval fails, the system has already prepared the necessary context data, allowing the handover to continue without requiring the user terminal to perform a complete RACH procedure again, thus reducing service disruption time and maintaining reliability
Solution Approach 2:
The patent introduces an intermediary mechanism where the target base station communicates with the source base station to retrieve user context information. This intermediary context retrieval process allows the system to maintain handover reliability by ensuring the target base station has all necessary information before finalizing the connection, avoiding the need for repeated RACH procedures
2Reliability
If the target base station retrieves user context from the source base station, then the connection setup is enhanced, but the device complexity increases
Solution Approach 1:
The context retrieval mechanism implemented in the target base station serves multiple functions: it enables reliable connection setup, facilitates handover continuity, and provides fallback capability when direct context retrieval fails. This multi-functional approach justifies the added complexity by delivering multiple reliability benefits through a single mechanism
3Productivity
If the user terminal continues handover without another RACH procedure after context retrieval failure, then the service disruption is reduced, but the protocol complexity increases
Solution Approach 1:
The handover protocol is made dynamic by allowing the target base station to adapt its behavior based on context retrieval status. When context retrieval succeeds, the standard handover procedure follows one path; when it fails, the system dynamically adjusts by allowing the user terminal to continue without repeating RACH, optimizing efficiency while managing complexity through conditional logic
Data Source
AI summary
Method and apparatus for facilitating inter-cell connections, such as during a forward handover or radio link failure (RLF), are disclosed. A user terminal such as a UE may store identity information associated with a source cell, and use this information in accessing target or other cells subsequent to radio link failure so as to facilitate access to context information of the user terminal. A base station may be configured to improve handover performance by associating context information with a newly assigned terminal identity. Handover performance may be enhanced by facilitating connection processing in the event of inability to retrieve user terminal context from a source cell.