HARQ-ACK Codebook Ordering for Multiple SPS Configurations
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Solution Overview
Problem
In future radio communication systems, such as New Radio (NR), semi-persistent scheduling (SPS) is used, but existing Rel-15 NR specifications do not allow for simultaneous configuration of multiple SPSs per cell group, leading to inadequate HARQ control and potential deterioration in communication throughput due to undefined Hybrid Automatic Repeat reQuest ACKnowledgement (HARQ-ACK) codebook configuration and uplink control channel resource allocation.
Innovation Solution
A user terminal is designed to generate an HARQ-ACK codebook containing only HARQ-ACK bits corresponding to SPS downlink shared channels, with specific ordering and transmission using an uplink control channel resource based on SPS configurations, allowing appropriate feedback even when multiple SPSs are utilized.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple SPSs are configured in one cell group for more flexible control, then adaptability is improved, but device complexity increases due to undefined HARQ-ACK codebook configuration and uplink control channel resource allocation
Solution Approach 1:
The patent segments the HARQ-ACK codebook into multiple parts, each corresponding to a different SPS configuration. This allows each SPS to have its own dedicated HARQ-ACK bits within the overall codebook structure, enabling multiple SPS configurations while maintaining organized and manageable codebook construction.
Solution Approach 2:
The patent introduces a new dimension for organizing HARQ-ACK bits by associating them with specific SPS configuration indices. This dimensional organization allows the system to handle multiple SPS configurations simultaneously by distinguishing their HARQ-ACK bits through the configuration index dimension, rather than requiring separate codebooks.
2Productivity
If multiple SPSs are configured with shorter cycles, then productivity is improved through more frequent scheduling, but reliability decreases due to inadequate HARQ control
Solution Approach 1:
The patent performs preliminary organization of HARQ-ACK bits according to a defined rule based on SPS configuration indices before transmission. This preliminary ordering ensures that when multiple SPSs with shorter cycles are used, each HARQ-ACK bit can be correctly associated with its corresponding SPS configuration, maintaining reliability even with increased scheduling frequency.
Solution Approach 2:
The patent establishes a clear feedback mechanism where HARQ-ACK bits are systematically ordered and transmitted according to SPS configuration indices. This structured feedback approach ensures that the base station can reliably interpret each ACK/NACK bit in the correct context, even when multiple SPS configurations are active with shorter cycles.
3Device complexity
If HARQ-ACK bits for multiple SPSs are contained in one codebook, then device complexity is reduced through unified transmission, but measurement precision decreases due to difficulty in determining appropriate uplink control channel resources
Solution Approach 1:
The patent determines the appropriate PUCCH resource in advance by associating it with a specific SPS configuration index. This preliminary resource determination, performed before transmission based on the ordered HARQ-ACK bits, allows the system to use a unified codebook while maintaining precise resource allocation by knowing which SPS configuration the codebook corresponds to.
Data Source
AI summary
A user terminal according to an aspect of the present disclosure includes a control section that generates a Hybrid Automatic Repeat reQuest ACKnowledgement (HARQ-ACK) codebook containing only HARQ-ACK corresponding to a semi-persistent scheduling (SPS) downlink shared channel (Physical Downlink Shared Channel (PDSCH)), so that HARQ-ACK bits corresponding to the PDSCH each SPS are ordered in accordance with a given rule, and a transmitting section that transmits an HARQ-ACK information bit corresponding to the HARQ-ACK codebook by using an uplink control channel resource based on an SPS corresponding to HARQ-ACK at a specific location in the order. According to an aspect of the present disclosure, it is possible to feed back HARQ-ACK appropriately even when a plurality of SPSs is utilized.