Terminal Uplink Timing Configuration for Handover Delay Reduction
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Solution Overview
Problem
In LTE cellular communication systems, handover processes between cells often experience delays due to the need for random access procedures and the absence of available UL-SCH resources, leading to inefficiencies in communication between terminal apparatuses and base station apparatuses.
Innovation Solution
A terminal apparatus is designed to configure transmission timing for PUSCH in a target cell based on received information, and initiates a random access procedure only when UL-SCH resources are available, avoiding unnecessary procedures and optimizing communication efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a random access procedure is performed during handover from source cell to target cell, then the handover can be completed with proper resource allocation, but the handover delay increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring uplink resources (PUSCH) and transmission timing information in the handover command before the terminal actually needs to transmit in the target cell. This allows the terminal to immediately transmit uplink data without performing a random access procedure, thereby reducing handover delay while ensuring reliable resource allocation.
2Loss of time
If UL-SCH resources are always allocated for handover command transmission, then handover delay is reduced, but resource utilization efficiency decreases when resources are not needed
Solution Approach 1:
The patent implements dynamics by making the allocation of uplink resources conditional rather than static. The handover command includes PUSCH transmission timing information only when uplink data needs to be transmitted during handover. The base station dynamically determines whether to include this information based on the terminal's uplink data status, thereby optimizing resource utilization while reducing handover delay when needed.
3Reliability
If the terminal initiates random access procedure when SR is pending and no PUCCH resource is available, then scheduling requests can be transmitted, but handover delay increases and communication efficiency decreases
Solution Approach 1:
The patent extracts the scheduling request transmission function from the random access procedure by providing dedicated PUCCH resources in the handover command. Instead of requiring the terminal to initiate a random access procedure to transmit SR, the terminal can directly transmit SR on the pre-configured PUCCH resources, thereby maintaining reliability while improving communication efficiency and reducing delay.
Data Source
AI summary
A terminal apparatus configures transmission timing for a PUSCH in a target cell based on first information included in a handover command received. The terminal apparatus initiates a random access procedure in a primary cell, at least in a case that an SR is pending, a UL-SCH resource is not available for transmission in a current subframe, and a valid PUCCH resource for the SR is not available in any one of subframes. The terminal apparatus does not initiate the random access procedure in the primary cell, in the case that the SR is pending, the UL-SCH resource is not available for the transmission in the current subframe, and the valid PUCCH resource for the SR is not available in any one of the subframes, and at least in a case that the first information is configured.