HARQ-ACK Feedback Codebook for Multi-PDSCH Slot Scheduling
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Solution Overview
Problem
In wireless communication systems, particularly in 5G networks operating above 52.6 GHz, the increased subcarrier spacing leads to higher PDCCH monitoring burden and reduced coverage due to shorter symbol duration, making it challenging to efficiently manage PDCCH monitoring and scheduling for multiple PDSCHs, especially with existing HARQ-ACK codebooks being either excessively large or prone to errors.
Innovation Solution
Implementing a method and apparatus for determining candidate slots for PDSCH reception and providing feedback information using a feedback codebook, which includes determining sets of candidate slots based on configured slot timing values and receiving indications for feedback, allowing for efficient HARQ-ACK feedback even with multi-PDSCH scheduling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If subcarrier spacing is increased to support higher frequency operation above 52.6 GHz, then communication coverage is maintained, but PDCCH monitoring burden increases and symbol duration decreases
Solution Approach 1:
The PDSCH reception occasions are segmented into multiple candidate slots within a PDSCH scheduling set. Instead of monitoring every slot, the UE identifies and monitors only specific candidate slots based on K1 values and slot offsets, dividing the monitoring task into manageable segments that reduce overall monitoring burden while maintaining coverage.
Solution Approach 2:
The system implements periodic PDCCH monitoring at specific intervals defined by the PDSCH scheduling set and candidate slot configurations. Rather than continuous monitoring, the UE performs monitoring at periodic intervals determined by the configured parameters, reducing monitoring burden while ensuring timely feedback for maintained coverage.
2Loss of information
If HARQ-ACK codebook size is increased to accommodate multiple PDSCHs, then feedback completeness is improved, but feedback overhead and processing complexity increase
Solution Approach 1:
The HARQ-ACK codebook is segmented and constructed dynamically based on the actual number of PDSCHs received within the PDSCH scheduling set. Instead of using a fixed large codebook, the UE constructs a compact codebook that includes only the necessary ACK/NACK bits for received PDSCHs, reducing processing complexity while maintaining feedback completeness.
Solution Approach 2:
The codebook size and structure are made dynamic rather than static. The UE adapts the codebook construction based on the actual scheduling conditions, number of received PDSCHs, and candidate slot configurations. This dynamic approach allows the system to maintain complete feedback when needed while reducing overhead when fewer PDSCHs are scheduled.
3Productivity
If PDSCH scheduling density is increased to improve resource utilization, then spectral efficiency is improved, but PDCCH monitoring burden and scheduling complexity increase
Solution Approach 1:
The time-frequency resources are segmented into PDSCH scheduling sets with defined candidate slots. This segmentation allows the system to increase scheduling density within each set while maintaining manageable monitoring complexity by focusing on specific candidate slots rather than all possible slots, thus improving spectral efficiency without proportionally increasing monitoring burden.
Solution Approach 2:
The candidate slots and PDSCH scheduling sets are pre-configured and identified in advance based on K1 values and slot offsets. This preliminary identification of candidate slots allows the UE to prepare for monitoring efficiently, reducing the complexity of real-time scheduling decisions while enabling higher scheduling density through pre-planned resource allocation.
Data Source
AI summary
There is provided an apparatus, said apparatus comprising means for determining, at a user equipment, one or more sets of candidate slots for physical downlink shared channel reception for which feedback information is to be provided in a given slot, receiving at least one indication of resources within one of the one or more sets of candidate slots for which feedback information is to be provided in the given slot, determining a feedback codebook based on the one or more sets of candidate slots and the indication and providing feedback information according to the feedback codebook.