Adaptive HARQ Retransmission for 5G Control Channel Congestion
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Solution Overview
Problem
Current wireless communication standards face challenges in meeting latency constraints, particularly in scenarios with multiple URLLC users, due to limited capacity in downlink control resources, leading to increased delays and inefficiencies in retransmissions within 5G NR networks.
Innovation Solution
The implementation of a receiving network device that dynamically determines the starting position and length of retransmitted segments in a circular buffer based on minimizing sum reliability, allowing for optimized retransmissions with reduced feedback information and improved spectral efficiency by using a retransmission profile that adjusts resource allocation and modulation parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the capacity of downlink control resources (CORESET) is limited, then control channel congestion occurs and delays increase, but increasing CORESET capacity would consume more downlink resources and reduce resources available for data transmission
Solution Approach 1:
The patent extracts only the essential retransmission information from the full DCI message. Instead of transmitting complete DCI for retransmissions, the system sends compact indicators (such as redundancy version indicators, frequency hopping indicators, and resource allocation indicators) that reference previously transmitted scheduling information. This extraction principle reduces control channel payload size while maintaining retransmission functionality.
Solution Approach 2:
The patent performs preliminary action by transmitting full DCI scheduling grants before data transmission. The initial DCI message contains complete resource allocation, modulation and coding scheme, and other transmission parameters. When retransmissions are needed, the system refers back to this pre-transmitted scheduling information, eliminating the need to retransmit the entire DCI message and reducing control channel congestion.
2Speed
If multiple URLLC users are scheduled simultaneously, then latency constraints cannot be met due to control resource limitations, but reducing the number of scheduled users decreases system throughput
Solution Approach 1:
The patent applies partial action by transmitting only the necessary retransmission indicators rather than complete scheduling information. The system sends compact retransmission commands that include only the essential changes from the original transmission (such as redundancy version, frequency hopping flag, and resource allocation offset), allowing multiple URLLC users to be served simultaneously without overwhelming the control channel capacity.
3Reliability
If complete DCI messages are transmitted for each retransmission, then all transmission parameters are updated, but control channel overhead increases and spectral efficiency decreases
Solution Approach 1:
The patent inverts the conventional approach by not transmitting the complete DCI message for retransmissions. Instead of sending all scheduling parameters again, the system transmits only the differences or indicators of changes from the original transmission. This inversion principle reduces control channel overhead while maintaining transmission reliability through selective parameter updates.
Data Source
Figure 1A~1B
Figure 2A
Figure 2B
AI summary
Devices, methods and computer programs for adaptively selective retransmissions in wireless communications are disclosed. The invention allows enhancing short packet data retransmission performance under short delay constraints. Using a retransmission indication for at least one segment of consecutive FEC encoded bits reduces feedback signaling overhead compared to signaling retransmission requests individually for each of the coded bits. Accordingly, active HARQ transmissions with low amounts of feedback information are enabled.