UE Random Access Control for Parallel Candidate Cell Handover
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Solution Overview
Problem
In future radio communication systems, controlling uplink transmission during inter-cell mobility, particularly when switching between a serving cell and a candidate cell, is challenging due to unclear methods for random access procedures, which can degrade communication quality if not appropriately managed.
Innovation Solution
A terminal equipped with a receiving section for downlink control channels to trigger random access preambles for multiple candidate cells, allowing separate operations based on the number of candidate cells indicated, including those with and without monitoring of random access responses, to facilitate parallel random access procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If parallel random access procedures are supported for multiple candidate cells, then inter-cell mobility control is improved, but control complexity increases due to unclear UE operation methods
Solution Approach 1:
The patent segments the random access procedure control by introducing separate configuration parameters for different candidate cell types. Specifically, it divides candidate cells into those requiring RAR monitoring and those not requiring RAR monitoring, with distinct control mechanisms for each type. This segmentation resolves the contradiction by providing clear, differentiated control methods that reduce overall system complexity while maintaining reliable parallel random access procedures.
Solution Approach 2:
The patent implements dynamic control of random access procedures by enabling the UE to adaptively select between different random access methods (with RAR monitoring or without RAR monitoring) based on the specific candidate cell configuration. This dynamic approach allows the system to optimize control complexity for each individual case while maintaining reliable inter-cell mobility control across all scenarios.
2Reliability
If separate operations are implemented for parallel random access procedures, then communication quality is maintained, but device operation complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring the UE with separate operation parameters and procedures for different candidate cell types before the actual random access occurs. The network provides advance configuration information indicating whether RAR monitoring should be performed for each candidate cell, allowing the UE to prepare appropriate control methods in advance. This eliminates the need for complex real-time decision-making during the random access procedure, thereby maintaining communication quality while simplifying device operation.
3Reliability
If RAR monitoring is performed for all candidate cells, then timing advance acquisition reliability is improved, but processing time increases
Solution Approach 1:
The patent applies local quality by differentiating the random access procedure based on the specific characteristics of each candidate cell. Instead of uniformly applying RAR monitoring to all candidate cells, the system configures RAR monitoring only for those candidate cells where it is necessary for reliable timing advance acquisition. For candidate cells where timing advance can be acquired through other means or where RAR monitoring is not critical, the procedure is simplified by omitting RAR monitoring, thereby reducing overall processing time while maintaining timing advance acquisition reliability where needed.
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
A terminal according to one aspect of the present disclosure includes a receiving section that receives a downlink control channel supporting triggering of a random access preamble (PRACH) for a plurality of candidate cells, and a control section that judges, based on the downlink control channel, one or more candidate cells for which transmission of the PRACH is performed. The plurality of candidate cells include a first candidate cell with monitoring of a response signal (RAR) to the PRACH and a second candidate cell without monitoring of an RAR to the PRACH. The control section performs control to perform a separate operation in a case of parallel random access procedures, based on a number of the first candidate cells possible to be indicated by one downlink control channel being the downlink control channel.