HARQ-ACK Codebook Handling During 5G Bandwidth Part Switching
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Solution Overview
Problem
The existing wireless communication systems face challenges in efficiently transmitting uplink control information due to resource shortages and high-speed service demands, particularly in 5G networks, where dynamic bandwidth part changes and hybrid automatic repeat request (HARQ) processes are not optimally managed.
Innovation Solution
A user equipment (UE) in a wireless communication system adjusts its downlink bandwidth part (BWP) based on a physical downlink control channel (PDCCH) indication, excluding certain physical downlink shared channels (PDSCH) from the HARQ-ACK codebook, and determines PDSCH candidate sets based on availability, timing, and symbol allocation to optimize uplink control information transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If dynamic bandwidth part changes are implemented to adapt to varying data traffic directions, then spectral efficiency and resource allocation flexibility are improved, but HARQ process management complexity and uplink control information transmission efficiency deteriorate
Solution Approach 1:
The patent segments the HARQ-ACK codebook into two distinct types: semi-static HARQ-ACK codebook and dynamic HARQ-ACK codebook. The semi-static codebook includes HARQ-ACK information for PDSCH scheduled by PDCCH in the current and past downlink BWPs, while the dynamic codebook includes HARQ-ACK information for PDSCH scheduled by PDCCH in future downlink BWPs. This segmentation allows the UE to manage HARQ processes more effectively during BWP changes, resolving the complexity issue while maintaining adaptability.
Solution Approach 2:
The patent applies preliminary action by pre-configuring the UE with the semi-static HARQ-ACK codebook before BWP changes occur. The semi-static codebook is prepared in advance based on the current and past downlink BWPs, allowing the UE to transmit HARQ-ACK information without waiting for real-time processing during BWP transitions. This reduces the processing burden and manages complexity during dynamic adaptations.
2Reliability
If HARQ-ACK codebook includes all PDSCH candidates to ensure complete feedback, then reliability of control information transmission is improved, but uplink resource utilization and transmission efficiency deteriorate
Solution Approach 1:
The patent segments the HARQ-ACK codebook into semi-static and dynamic portions, allowing the UE to selectively include only relevant PDSCH HARQ-ACK information in each portion. The semi-static portion covers past and current BWPs where feedback is reliably needed, while the dynamic portion handles future BWPs. This segmentation enables efficient resource utilization by avoiding inclusion of irrelevant future PDSCH candidates while maintaining complete feedback for actual transmissions.
Solution Approach 2:
The patent applies partial action by including only the necessary HARQ-ACK information for PDSCH that have actually been transmitted or will be transmitted in the near future. The semi-static codebook includes HARQ-ACK for PDSCH scheduled by PDCCH in current and past downlink BWPs, while excluding PDSCH from future BWPs that have not been scheduled yet. This partial inclusion strategy maintains reliability for actual transmissions while avoiding waste on unscheduled future transmissions.
3Reliability
If the UE transmits uplink control information in every downlink slot to maintain continuous feedback, then reliability of communication is improved, but uplink resource consumption and transmission time increase
Solution Approach 1:
The patent implements periodic action by configuring the UE to transmit uplink control information only in specific downlink slots based on a periodic pattern. The gNodeB configures the UE with periodicity parameters that determine when HARQ-ACK feedback should be transmitted. This allows the system to maintain reliable feedback communication while reducing uplink resource consumption by skipping unnecessary transmission opportunities in certain slots.
Solution Approach 2:
The patent applies preliminary action by pre-configuring the UE with the semi-static HARQ-ACK codebook and transmission timing parameters before actual communication occurs. The semi-static codebook is prepared in advance based on configured BWPs and timing information, allowing the UE to transmit HARQ-ACK feedback at predetermined intervals without needing to continuously monitor and transmit in every slot. This reduces transmission time while maintaining reliability through configured periodic feedback.
Data Source
AI summary
A base station of a wireless communication system is disclosed. The base station of the wireless communication includes a communication module, and a processor. The processor is configured to, when receiving a physical downlink control channel (PDCCH) indicating a change of a downlink (DL) bandwidth part (BWP), change the DL BWP based on the PDCCH indicating the change of the DL BWP, and not include a physical downlink shared channel (PDSCH) scheduled by a PDCCH received before receiving the PDCCH indicating the change of the DL BWP in a PDSCH candidate set, and transmit a semi-static HARQ-ACK codebook including hybrid automatic repeat request (HARQ)-ACK information of a physical downlink shared channel (PDSCH) corresponding to the PDSCH candidate set to a base station of the wireless communication system.