Dynamic CBG Granularity for HARQ Feedback in NR-U
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Solution Overview
Problem
In wireless communication networks, especially in NR-U operations, the existing HARQ processes face challenges in configuring optimal CBG granularity, leading to inefficiencies in acknowledgement feedback and increased communication latency due to the need for medium-sensing procedures in shared spectrum access, particularly when multiple network operating entities contend for resources.
Innovation Solution
The method involves transmitting a semi-static configuration signal to UEs to configure available CBG granularities for acknowledgement feedback, allowing UEs to select the appropriate granularity based on control signaling and perform feedback accordingly, while base stations detect acknowledgement feedback in the corresponding format and update the contention window size based on transmission failure rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fixed CBG granularity is used in HARQ processes, then device complexity is reduced, but communication efficiency deteriorates due to inability to adapt to varying channel conditions and traffic types
Solution Approach 1:
The patent implements dynamic CBG granularity selection where the granularity is not fixed but adapts based on channel conditions, traffic type, and slot type. The system determines optimal CBG granularity dynamically through monitoring channel quality indicators and traffic characteristics, then adjusts the granularity accordingly to maximize communication efficiency under varying conditions.
Solution Approach 2:
The patent changes the CBG granularity parameter based on different operating conditions. Specifically, it adjusts the number of code blocks per CBG and the CBG size according to channel quality, traffic type (e.g., URLLC, eMBB, mMTC), and slot type (boundary vs. non-boundary slots), allowing the system to optimize performance by modifying this critical parameter in response to environmental changes.
2Reliability
If medium-sensing procedures are performed in shared spectrum access, then interference is reduced, but communication latency increases due to additional sensing time before transmission
Solution Approach 1:
The patent performs preliminary medium-sensing procedures before actual data transmission in shared spectrum. The system monitors channel availability and performs clear channel assessment (CCA) in advance, determining whether the channel is free before initiating transmission. This preliminary action ensures reliable interference management by avoiding collisions with other transmissions while the latency is minimized through efficient sensing procedures and parallel processing where possible.
3Productivity
If multiple network operating entities contend for shared spectrum resources, then spectrum utilization is improved, but interference increases leading to degraded communication performance
Solution Approach 1:
The patent implements feedback mechanisms where each network operating entity monitors the channel conditions, detects interference from other entities, and adjusts its transmission parameters accordingly. The system uses channel quality indicators, interference measurements, and acknowledgment feedback to dynamically adjust transmit power, select appropriate resources, and modify modulation schemes, creating a feedback loop that balances spectrum utilization with interference management in shared spectrum environments.
Data Source
AI summary
Hybrid automatic repeat request (HARQ) configurability on new radio (NR) unlicensed (NR-U) operations is disclosed. Time varying code block group (CBG) granularity may be defined by signaling a set of available CBG granularities to a user equipment (UE) for HARQ feedback. The UE monitors for control signaling that may be used to select the CBG granularity for the current slot. The UE may then perform HARQ feedback according to a format corresponding to the selected CBG granularity. Additional aspects disclose updating a contention window size (CWS) in NR-U operations considering the varying CBG granularity. A base station may compute an effective HARQ feedback value that accounts for the varied CBG granularity corresponding to transmissions at a configurable reference slot of set of slots. The base station will update the CWS depending on the relationship of the failure rate of the effective HARQ feedback and a transmission failure rate threshold.