Point-to-Multipoint CSI Reporting With NACK-Only HARQ Feedback
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Solution Overview
Problem
Existing methods for channel state information (CSI) reporting in multicast and broadcast systems (MBS) do not effectively address the high signaling overhead and resource inefficiency caused by HARQ feedback in point-to-multipoint (PTM) transmissions, particularly when multiple user equipment (UEs) are consuming the service, leading to bursty errors and inconsistent reliability.
Innovation Solution
A method where a network device configures UEs with a block error rate (BLER) target and a number of HARQ transmissions to determine Channel Quality Indicator (CQI) for CSI reporting, enabling efficient and reliable PTM service delivery by incorporating NACK-only HARQ feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HARQ feedback is implemented in PTM transmissions for MBS services, then reliability is improved, but signaling overhead increases and resource efficiency deteriorates
Solution Approach 1:
The patent extracts only the necessary HARQ feedback information (NACK-only feedback) rather than transmitting complete ACK/NACK feedback for all transmissions. This selective extraction reduces signaling overhead while maintaining reliability by focusing only on failed transmissions that require retransmission.
Solution Approach 2:
Instead of the conventional approach where successful transmissions are acknowledged (ACK) and failures are indicated (NACK), the patent inverts this by sending feedback only when transmission fails (NACK-only). This inversion eliminates redundant ACK signaling and reduces overhead significantly in PTM scenarios.
2Adaptability or versatility
If CSI reporting is configured for multiple UEs in PTM transmissions, then service coverage is improved, but resource inefficiency increases
Solution Approach 1:
The patent implements a universal CSI reporting mechanism where a single configuration can serve multiple UEs simultaneously. The gNB configures CSI reporting parameters that apply to all UEs receiving the MBS service, allowing the system to efficiently manage service coverage for multiple users without requiring individualized configurations for each UE.
Solution Approach 2:
The patent merges CSI reporting configurations across multiple UEs by using group-based or cell-wide configuration parameters. Instead of managing separate CSI reporting for each UE, the system combines the configuration into a unified approach that reduces signaling overhead and improves resource efficiency while maintaining adaptability for multiple users.
3Reliability
If accurate BLER estimation is performed for CQI determination, then transmission reliability is improved, but computational complexity increases
Solution Approach 1:
The patent performs preliminary BLER estimation and CQI determination based on pre-configured parameters and historical data before actual transmission. By pre-calculating these values and storing them for reference, the system reduces real-time computational complexity while maintaining accurate BLER estimation for reliable transmission decisions.
Solution Approach 2:
The patent uses simplified, lightweight algorithms for BLER estimation that require minimal computational resources. Instead of complex iterative methods, the system employs straightforward calculations based on configured parameters and immediate feedback, providing sufficient accuracy with much lower computational complexity suitable for real-time operation.
Data Source
AI summary
Embodiments of the present disclosure relate to methods, apparatuses and computer readable storage media for channel state information (CSI) reporting. According to embodiments of the present disclosure, a first device receives from a second device a configuration for CSI reporting. The configuration comprises at least a block error rate target and an indication of a number of HARQ transmissions. The first device determines Channel Quality Indicator (CQI) based on the block error rate target and the number of HARQ transmissions indicated by the configuration and transmits a CSI report comprising the CQI to the second device. The solution enables CSI feedback that is suitable for spectrally efficient and reliable delivery of Point to Multipoint services while meeting the delay requirement, in particular in the context of NACK-only feedback on common feedback resources.