HARQ Process Control in 5G NTN Handover via Broadcast Signaling
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Solution Overview
Problem
Current wireless communication systems, such as 5G New Radio (NR), face challenges in optimizing HARQ processes during handover procedures, particularly in non-terrestrial networks (NTNs), which affect data rate, latency, and reliability.
Innovation Solution
A method and system for controlling HARQ processes in user equipment (UE) and base stations (BS) that involves receiving a handover command with HARQ feedback or state configurations, and applying these configurations during the handover process to optimize HARQ operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HARQ feedback configuration is applied during handover in NTN environments, then reliability of HARQ processes is improved, but device complexity increases due to additional configuration management
Solution Approach 1:
The patent applies preliminary action by pre-configuring HARQ feedback configurations and states in the handover command message before the actual handover occurs. The UE receives and stores the HARQ feedback configuration (including bit strings for enabling/disabling feedback per HARQ process) and HARQ state configuration (indicating whether UL retransmission grant reception is enabled or disabled) in advance, so that when handover executes, the configurations are already in place, improving reliability without adding operational complexity during the handover moment.
2Productivity
If multiple HARQ processes are activated with specific configurations, then data transmission efficiency is improved, but loss of time increases due to configuration application overhead
Solution Approach 1:
The patent eliminates configuration application overhead by including all HARQ feedback configurations and states directly in the handover command message received via broadcast signaling. The UE applies these configurations immediately upon receiving the handover command and selecting the candidate cell as target cell, without requiring separate configuration messages or processing steps, thus achieving efficient multi-HARQ process activation without time loss.
3Reliability
If HARQ state configuration is applied to control UL retransmission grants, then reliability of uplink communications is improved, but device complexity increases due to additional state tracking
Solution Approach 1:
The patent applies local quality by providing per-HARQ-process state configurations through bit strings in the handover command. Each bit in the HARQ state configuration bit string corresponds to a specific HARQ process and indicates whether reception of UL retransmission grants is enabled or disabled for that process. This allows the UE to track only the specific states relevant to each HARQ process rather than maintaining complex global state information, improving uplink reliability while minimizing device complexity.
Data Source
AI summary
A method performed by a user equipment (UE) for controlling a hybrid automatic repeat request (HARQ) process is provided. The method includes receiving a handover command from a serving cell via broadcast signalling, the handover command including at least one of a HARQ feedback configuration or a HARQ state configuration associated with a candidate cell for a handover procedure; and applying the at least one of the HARQ feedback configuration or the HARQ state configuration after selecting the candidate cell as a target cell during the handover procedure.