Fixed-Length DCI Detection Parameters for 5G NR-U Retransmission
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Solution Overview
Problem
The existing 5G NR-U technology faces excessive signaling overhead due to large UL grant scheduling for retransmissions in unlicensed frequency bands, particularly when multiple HARQ processes require feedback, leading to increased complexity and power consumption in blind detection at the UE.
Innovation Solution
A two-stage DCI feedback mechanism is introduced, where a fixed-length DCI carries detection parameters for a variable-length DCI, reducing blind detection complexity and signaling overhead by indicating feedback information at both transport block and code block group levels, allowing adaptive resource allocation and retransmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UL grant scheduling is used for retransmission in NR-U technology, then retransmission can be scheduled on dedicated resources, but signaling overhead becomes excessively large
Solution Approach 1:
The patent extracts only the necessary feedback information (HARQ-ACK bits) from the complete DCI structure. Instead of transmitting full UL grant DCI for retransmission scheduling, the system sends a compact DCI format containing only the essential HARQ-ACK feedback bits, thereby removing unnecessary signaling overhead while preserving retransmission functionality
Solution Approach 2:
The patent changes the parameter structure of DCI by introducing different DCI format types (full DCI vs. compact DCI). The compact DCI format uses a reduced parameter set containing only HARQ-ACK feedback bits, transforming the original large-size DCI into a streamlined version that reduces signaling overhead by approximately half while maintaining essential retransmission scheduling capability
2Productivity
If multiple HARQ processes are supported with detailed feedback, then retransmission efficiency improves, but blind detection complexity at UE increases
Solution Approach 1:
The patent segments the feedback mechanism into two distinct parts: (1) Downlink DCI carrying HARQ-ACK feedback bits for multiple HARQ processes, and (2) Uplink DCI for scheduling retransmission resources. This segmentation allows the UE to first decode the compact downlink DCI to obtain feedback information, then use this information to guide selective decoding of uplink DCI, thereby reducing blind detection complexity while supporting multiple HARQ processes
Solution Approach 2:
The patent implements preliminary action by having the gNB send HARQ-ACK feedback bits in the downlink DCI before the UE needs to perform blind detection for uplink DCI. The UE uses this advance feedback information to determine which HARQ processes require retransmission, thereby reducing the search space for blind detection of subsequent uplink DCI messages
Data Source
AI summary
A data transmission method includes: sending, by a network device, a fixed-length downlink control information (DCI), wherein the fixed-length DCI comprises a detection parameter corresponding to a variable-length DCI.