Primary Cell Change in Uplink NRCA Scenarios
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Solution Overview
Problem
In 5G wireless communications, uplink congestion leads to primary cell changes, causing performance disruptions and call disruptions due to power limitations of user equipment, especially when an active secondary cell is present.
Innovation Solution
A method is introduced to dynamically change the primary cell in uplink New Radio Carrier Aggregation (NRCA) scenarios by comparing the negative acknowledgement (NACK) rate and effective uplink bandwidth of the primary serving cell with that of secondary cells, allowing a seamless switch when the difference meets predetermined thresholds, ensuring stable connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If primary cell is changed to a new primary cell when uplink congestion is encountered, then uplink congestion is relieved, but user experiences performance disruption and call disruption
Solution Approach 1:
The system performs preliminary evaluation by comparing NACK rates and effective uplink bandwidth of secondary cells before triggering primary cell change. This preliminary assessment ensures that the target secondary cell is ready to immediately assume primary cell functions, minimizing disruption. The comparison of NACK rates and bandwidth metrics allows the system to pre-identify suitable candidate cells, so when congestion occurs, the switch can happen seamlessly without call drops or performance degradation.
2Productivity
If primary cell is changed from primary serving cell to secondary cell, then uplink congestion is relieved, but connection stability may be affected
Solution Approach 1:
The system continuously monitors NACK rates and effective uplink bandwidth of both primary and secondary cells, creating a feedback mechanism that tracks uplink congestion in real-time. When the NACK rate exceeds a threshold or bandwidth difference falls below a threshold, the system triggers a controlled primary cell change to a secondary cell with better uplink conditions. This feedback-driven approach ensures connection stability is maintained by only switching when necessary and to cells that have been verified to have adequate capacity.
3Reliability
If NACK rate comparison and bandwidth comparison are performed, then optimal primary cell change is achieved, but system complexity increases
Solution Approach 1:
The system evaluates secondary cells based on two key parameters: NACK rate (negative acknowledgement rate) and effective uplink bandwidth. By focusing on these specific parameters rather than comprehensive cell analysis, the system achieves optimal cell selection with manageable complexity. The NACK rate indicates uplink congestion level, while effective bandwidth indicates available capacity. These parameter comparisons provide a simplified yet effective decision-making framework for determining when and where to change the primary cell.
Data Source
AI summary
A method for primary cell change in an uplink NRCA scenario is provided. An uplink NRCA is configured and active for a UE on a primary serving cell when a NACK rate of the primary serving cell uplink is compared with a predetermined NACK rate threshold for defined TTI slots. The NACK rate of the primary serving cell uplink is compared with the NACK rate of at least one secondary cell uplink for the TTI slots. An effective uplink bandwidth of the primary serving cell is compared with an effective uplink bandwidth of the at least one secondary cell. When the difference between the effective uplink bandwidths is less than a predetermined effective bandwidth difference threshold, the UE is instructed to change from the primary serving cell to the at least one secondary cell.