URLLC Control Channel Reliability with Multi-CORESET DCI Combining
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Solution Overview
Problem
The existing NR wireless communication systems face challenges in ensuring ultra-reliable low-latency communication (URLLC) due to limitations in control channel reliability and data channel reliability, particularly when resources for CORESETs are constrained, leading to suboptimal performance in meeting stringent latency and reliability requirements for applications like factory automation and remote surgery.
Innovation Solution
Implementing mechanisms to enhance reliability by transmitting multiple DCIs across different CORESETs, BWPs, or CCs, and employing soft combining techniques at the UE, along with non-slot-based scheduling and CBG-based transmission with separate HARQ-ACK feedback to improve data throughput and latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple DCIs are transmitted across different CORESETs to enhance reliability, then control channel reliability is improved, but device complexity increases
Solution Approach 1:
The control information is divided into multiple DCIs distributed across different CORESETs. Each CORESET transmits a portion of the control information independently, allowing the UE to combine these segments to achieve enhanced reliability without requiring a single complex transmission system.
Solution Approach 2:
Multiple DCIs from different CORESETs are combined at the UE through soft combining techniques. The UE receives and processes multiple copies of control information across different CORESETs, merging them to improve decoding reliability and reduce errors in control channel transmission.
2Loss of time
If non-slot-based scheduling is implemented to reduce latency, then time efficiency is improved, but device complexity increases
Solution Approach 1:
The scheduling mechanism transitions from static slot-based scheduling to dynamic non-slot-based scheduling. This allows the gNodeB to allocate resources more flexibly based on real-time needs, reducing latency by eliminating fixed slot boundaries while managing the increased complexity through dynamic control algorithms.
3Reliability
If CBG-based transmission with separate HARQ-ACK feedback is used to improve reliability, then data channel reliability is improved, but device complexity increases
Solution Approach 1:
The data channel transmission is segmented into Code Block Groups (CBGs) instead of transmitting entire transport blocks. Each CBG can be independently acknowledged with separate HARQ-ACK feedback, allowing selective retransmission of only failed CBGs and improving reliability while managing complexity through structured segmentation.
Solution Approach 2:
Separate HARQ-ACK feedback is implemented for each CBG, enabling the receiver to provide individual acknowledgment status for each code block group. This feedback mechanism allows the transmitter to identify and retransmit only the failed CBGs, improving reliability through targeted retransmission while managing complexity through efficient feedback processing.
4Productivity
If resources for CORESETs are constrained, then spectrum efficiency is improved, but control channel reliability deteriorates
Solution Approach 1:
Multiple DCIs are combined across different CORESETs to achieve the desired reliability. By distributing control information across multiple CORESETs and using soft combining at the UE, the system maintains control channel reliability even when individual CORESET resources are constrained, effectively utilizing limited spectrum resources.
Data Source
AI summary
The disclosure describes mechanisms for reliability enhancement on control channel and data channel and mechanisms in URLLC. An apparatus of a RAN node for URLLC includes baseband circuitry to configure at least one DCI for scheduling transmission of at least one PDSCH content having same information. For each DCI, the baseband circuitry determines a CORESET for transmitting the DCI. The disclosure further describes mechanisms for the support of low latency transmission in URLLC. To improve peak data rate and spectrum efficiency in FDD system, the RAN node configures a DCI for scheduling data transmission using blank resources of a self-contained slot structure. Further, CBG-based transmission with separate HARQ-ACK feedback is provided to configure a DCI for scheduling data transmission of a TB and to divide the TB into multiple CBGs, and to configure uplink control data to carry separate HARQ feedback for the CBGs.