Dual Active Link Handover Error Handling for Conflicting Slots
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Solution Overview
Problem
In wireless communications systems, UEs experience packet loss and latency during dual active link handover due to conflicting transmission opportunities with multiple base stations, leading to inefficiencies in managing concurrent connections.
Innovation Solution
Implementing dual active link handover procedures with prioritization rules, re-transmissions, slot aggregation, and notification messages to manage transmission opportunities and reduce packet loss and latency, including configuring re-transmission timers and slot aggregation configurations to provide additional reception opportunities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a UE operates one panel at a time and forms a reception beam in one direction at a time, then the device complexity is reduced, but packet loss occurs during dual active link handover due to inability to switch in time between base stations
Solution Approach 1:
The UE performs beam switching in advance before the actual handover occurs. The UE switches reception beams proactively when detecting upcoming transmission opportunities from different base stations, ensuring the correct beam is ready before packets need to be received, thereby preventing packet loss without requiring complex simultaneous multi-panel operations
Solution Approach 2:
The UE dynamically adjusts its reception beam direction based on the current active transmission opportunity. By making the beam direction adaptive and time-varying rather than static, the UE can efficiently switch between base stations during handover without maintaining complex simultaneous beam configurations
2Productivity
If the UE switches reception beams quickly between base stations, then the productivity increases by reducing interruption time, but measurement precision deteriorates due to insufficient time to accurately measure signal quality
Solution Approach 1:
The UE performs preliminary beam measurements during earlier transmission opportunities before the actual handover decision is made. By measuring signal quality in advance during the dual active period, the UE accumulates sufficient measurement data without needing to perform rapid measurements during the critical handover switch, thus maintaining both speed and accuracy
Solution Approach 2:
The UE performs periodic beam measurements at scheduled intervals during the handover process rather than continuously. This periodic measurement approach provides sufficient measurement opportunities to maintain accuracy while allowing the handover to proceed without unnecessary delays, balancing measurement precision with handover speed
3Reliability
If the UE monitors all transmission opportunities from multiple base stations concurrently, then the reliability improves by receiving all packets, but the loss of time increases due to the UE unable to switch in time between opportunities
Solution Approach 1:
The UE extracts and prioritizes only the most critical transmission opportunities that must be monitored during dual active link handover. By selecting specific high-priority transmission opportunities rather than monitoring all opportunities from all base stations, the UE maintains packet reception reliability for essential data while reducing the time loss associated with switching between numerous transmission opportunities
Solution Approach 2:
The UE applies different monitoring strategies to different transmission opportunities based on their local characteristics. High-priority transmissions receive full monitoring attention with dedicated beam switching, while lower-priority transmissions use more efficient switching patterns, optimizing the balance between reliability and time loss on a per-transmission basis
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. In some systems, a user equipment (UE) may perform a dual active link handover procedure from a source base station to a target base station. During the dual active link handover procedure, the UE may have connections to both of the base stations concurrently. In such cases, transmission opportunities for communicating with the base stations may conflict. To handle conflicting transmission opportunities, the UE may drop a monitoring occasion or a packet reception for a base station based on prioritization rules. In some cases, to mitigate packet losses, the base station may configure re-transmissions or slot aggregation to provide the UE with additional opportunities to receive a packet. Additionally or alternatively, the UE may transmit a notification message to a base station indicating dropped monitoring occasions or packets.