Uplink Switch Gap Detection in Carrier Aggregation
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Solution Overview
Problem
In wireless communication systems, particularly in carrier aggregation scenarios, there is a challenge in detecting and managing uplink switch gaps due to the need for transmit chain reconfiguration between different radio frequency spectrum bands, which can lead to timing mismatches and missed uplink transmissions.
Innovation Solution
The proposed solution involves mechanisms for carrier aggregation uplink switch gap detection and report, where user equipment (UE) signals its switching time in a UE capability message, and the base station selects a monitoring window based on this capability to schedule and detect uplink transmissions accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the base station schedules uplink transmissions without considering UE transmit chain reconfiguration time, then scheduling efficiency is improved, but transmission reliability deteriorates due to timing mismatches and missed transmissions
Solution Approach 1:
The UE performs transmit chain reconfiguration in advance before the scheduled uplink transmission time. The UE determines a reconfiguration completion time based on its capability (e.g., retuning time) and ensures the transmit chain is ready before the base station's monitoring window begins, preventing timing mismatches while maintaining efficient scheduling.
Solution Approach 2:
The UE provides feedback to the base station about its transmit chain reconfiguration capability and status. The base station uses this feedback to adjust scheduling decisions, monitoring window timing, and resource allocation, ensuring transmissions are scheduled when the UE is actually ready to transmit, thus improving reliability without significantly compromising scheduling efficiency.
2Reliability
If the base station extends the monitoring window duration to accommodate reconfiguration delays, then transmission reliability is improved, but time resource utilization deteriorates
Solution Approach 1:
The monitoring window duration and timing are dynamically adjusted based on UE-specific parameters such as reconfiguration capability, current transmit chain state, and traffic conditions. Instead of using a fixed extended window, the base station optimizes the monitoring window to start and end at precise times that account for the specific UE's reconfiguration characteristics, reducing unnecessary time loss while maintaining reliable detection.
Solution Approach 2:
The monitoring window is made dynamic rather than static. The base station can adjust the monitoring window timing and duration in real-time based on UE feedback about reconfiguration status, allowing the system to adapt to varying conditions and minimize time loss while ensuring reliable transmission detection.
3Adaptability or versatility
If the UE performs frequent transmit chain retuning between component carriers, then carrier aggregation flexibility is improved, but transmission timing accuracy deteriorates due to reconfiguration overhead
Solution Approach 1:
The UE performs transmit chain retuning in advance of scheduled transmissions on different component carriers. By proactively reconfiguring the transmit chain before needed and caching the completion time information, the UE minimizes the impact of retuning operations on transmission timing accuracy, allowing frequent carrier switching without compromising precision.
Solution Approach 2:
The system builds in a time cushion or buffer that accounts for the maximum expected retuning duration. The UE and base station coordinate timing with this cushion built in, allowing the UE to perform retuning operations without risking missed transmissions, thus maintaining timing accuracy even with frequent carrier aggregation retuning.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A user equipment (UE) may receive, from a base station, an indication of a monitoring window used by the base station to monitor for uplink transmissions from the UE. The UE may receive a control signal scheduling uplink resources for an uplink transmission by the UE on at least a first component carrier, the first component carrier in a first radio frequency spectrum band. The UE may reconfigure, in response to the received control signal, a first transmit chain of the UE from a second component carrier in a second radio frequency spectrum band to the first component carrier in the first radio frequency spectrum band for the uplink transmission. The UE may transmit, based at least in part on the indicated monitoring window and using at least the reconfigured first transmit chain, the uplink transmission on the first component carrier using the scheduled uplink resources.