UE Timer-Based Cell Reestablishment for Call Drop Mitigation
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Solution Overview
Problem
Existing wireless communication systems face issues with call drops due to prolonged waiting times for uplink grants during poor radio channel conditions, leading to inefficient resource utilization and increased power consumption, especially in scenarios like urban areas with fluctuating signal strength.
Innovation Solution
Implementing a timer-based mechanism in user equipment (UE) that tracks the duration since the initial scheduling request, independent of the scheduling request counter, to trigger a connection reestablishment to a better cell if no valid uplink grant is received within the specified time, thereby avoiding excessive retransmissions and reducing call drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE continuously retransmits scheduling requests waiting for uplink grant, then the probability of receiving uplink grant increases, but the call drop risk increases and power consumption increases
Solution Approach 1:
The patent applies preliminary action by introducing a timer that starts counting down when a scheduling request is transmitted. This timer represents advance preparation for the worst-case scenario (never receiving an uplink grant), allowing the UE to proactively switch cells before excessive retransmissions occur, thereby reducing power consumption while maintaining reliable connection establishment.
Solution Approach 2:
The patent implements feedback through the timer mechanism that provides continuous feedback on the waiting state. When the timer expires without receiving an uplink grant, the system triggers a feedback action (cell switching) based on the accumulated waiting time, creating a closed-loop control that balances persistence with energy efficiency.
2Reliability
If the UE continuously retransmits scheduling requests waiting for uplink grant, then the probability of receiving uplink grant increases, but the call drop risk increases
Solution Approach 1:
The timer is configured with a predetermined expiration time that represents a threshold for acceptable waiting. This preliminary time limit allows the UE to persist in requesting uplink grants for a reasonable duration while automatically switching cells if the wait exceeds the threshold, thus reducing unnecessary time loss and call drops.
Solution Approach 2:
The patent introduces dynamic behavior by making the waiting period configurable and adjustable. The timer expiration time can be set based on network conditions and call type, allowing the system to adapt the waiting duration dynamically rather than using a fixed maximum, thereby optimizing the balance between persistence and time loss.
3Productivity
If the scheduling request counter is reset when SPS grant is available, then the number of retransmission opportunities increases, but the timer-based timeout mechanism becomes redundant
Solution Approach 1:
The patent segments the control logic into two independent components: the scheduling request counter (for tracking retransmission attempts) and the timer (for tracking waiting duration). This segmentation allows each mechanism to serve its specific purpose without interfering with the other, maintaining retransmission efficiency while adding timeout functionality without excessive complexity.
Solution Approach 2:
The timer acts as an intermediary mechanism that mediates between the scheduling request counter and the cell switching decision. Instead of directly linking counter resets to SPS grant availability, the timer provides an intermediate time-based control that triggers cell switching when appropriate, simplifying the overall control logic while maintaining productivity.
Data Source
AI summary
A method for voice communications includes: receiving, from a network entity affiliated with a first cell, control signaling activating a semi-persistent scheduling grant; preparing an initial scheduling request for transmission during a first scheduling request occasion in response to determining that a radio channel condition associated with the first cell is below a threshold value; starting a timer in response to transmitting the initial scheduling request during the first scheduling request occasion; and preparing a connection reestablishment request, for transmission to a network entity affiliated with a second cell, after failing to receive a valid uplink grant prior to expiration of the timer.