Handover Timing Advance Value for RACH-Free Uplink Sync
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Solution Overview
Problem
In dual-connectivity operations, handovers and re-establishments of Radio-Resource-Control (RRC) connections between Master eNB and Secondary eNB can be delayed due to the need for a Random Access Channel (RACH) procedure, which consumes time and resources, especially when a user equipment (UE) moves out of the Master eNB coverage area and needs to reconnect to a Secondary eNB.
Innovation Solution
The proposed solution involves transmitting a Timing-Advance Value from the Secondary eNB to the User Equipment (UE) as part of the handover command, allowing the UE to skip the RACH procedure and directly perform uplink synchronization, thereby facilitating faster handovers and re-establishments without the need for RACH Access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Random Access Channel (RACH) procedure is performed during handover, then uplink synchronization can be achieved, but handover time and resource consumption increase
Solution Approach 1:
The target eNB retrieves and provides the timing advance value to the UE in advance as part of the handover command, so that the UE can perform uplink synchronization without executing the RACH procedure, thereby reducing handover time while maintaining synchronization reliability
Solution Approach 2:
The patent extracts the timing advance value from the RACH procedure and provides it directly to the UE through the handover command, separating the synchronization function from the RACH procedure to eliminate unnecessary signaling overhead and time consumption
2Reliability
If a Random Access Channel (RACH) procedure is performed during handover, then random access control can be maintained, but resource consumption increases
Solution Approach 1:
The timing advance value is extracted from the RACH procedure and embedded in the handover command, allowing the UE to perform uplink synchronization without executing the full RACH procedure, thereby reducing signaling overhead and resource consumption while maintaining access control
Solution Approach 2:
The UE skips the RACH procedure entirely by using the pre-provided timing advance value from the handover command, rushing through the handover process directly to uplink synchronization, which reduces both time and resource consumption
Data Source
AI summary
A method and apparatus can be configured to detect that a signaling strength of a first network entity has dropped below a threshold. The method can also include transmitting a measurement report to the first network entity. The method can also include receiving radio-resource-control reconfiguration information from the first network entity. The method can also include transmitting a scheduling request to a second network entity, wherein a random-access-channel procedure is avoided.