DAPS Handover Timer and HARQ Configuration for NTN Delays
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Solution Overview
Problem
In wireless communication systems with non-terrestrial networks (NTNs), the propagation delays between user equipment (UE) and base stations can vary significantly, leading to issues during dual active protocol stack (DAPS) handovers due to inappropriate parameter configurations when switching between different types of networks, such as TNs and NTNs, or NTNs with varying satellite types, resulting in timer expirations, buffer overflow, and HARQ mode mismatches.
Innovation Solution
A method for configuring UE with a first set of parameters for a target cell during DAPS handover, including timers and HARQ settings tailored to the specific propagation delays and characteristics of the target cell, and optionally using source cell parameters when target cell parameters are absent or inappropriate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DAPS handover is performed between NTN and TN or different satellite types, then service continuity is improved, but parameter configuration becomes complex due to different propagation delays
Solution Approach 1:
The patent applies parameter changes by configuring different timer values and HARQ settings based on the propagation delay characteristics of the target cell. When a UE performs DAPS handover to a target cell with different propagation delay (e.g., switching between NTN and TN, or different satellite types), the network configures appropriate timer parameters and HARQ parameters specifically tailored to the target cell's propagation characteristics, ensuring reliable operation without manual intervention.
2Ease of operation
If source cell parameters are used for target cell during DAPS handover, then configuration simplicity is improved, but timer expiration and buffer overflow occur due to propagation delay mismatch
Solution Approach 1:
The patent applies local quality by configuring parameters specifically adapted to the target cell's local propagation delay characteristics rather than using generic or source cell parameters. The network configures timer values and HARQ parameters that are locally optimized for the target cell's propagation delay, ensuring that timers expire at appropriate times and buffers are properly managed for each specific target cell environment.
3Speed
If propagation delay is not considered in parameter configuration, then handover speed is improved, but HARQ mode mismatches and transmission errors occur
Solution Approach 1:
The patent applies preliminary action by pre-configuring appropriate HARQ parameters and timer values in the handover command message before the UE actually switches to the target cell. The network calculates and provides the correct HARQ parameters based on the target cell's propagation delay in advance, allowing the UE to immediately use the correct configuration upon handover completion, thus avoiding transmission errors without delaying the handover process.
Data Source
AI summary
The present application relates to methods and apparatuses for a parameter configuration during a dual active protocol stack (DAPS) handover in a non-terrestrial network (NTN) environment. One embodiment of the present disclosure provides a user equipment (UE), comprising: a transceiver; and a processor coupled with the transceiver, and the processor is configured to: receive, with the transceiver, a first set of parameters associated with a target cell for a dual active protocol stack (DAPS) handover; and apply the first set of parameters to the target cell for the DAPS handover.