Uplink Control Retransmission for HARQ-ACK Decode Failures
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Solution Overview
Problem
The large signaling overhead and low transmission reliability of uplink control information (UCI) in 3GPP 5G new radio (NR) networks, particularly due to power limitations, burst interference, and cross-link interference, result in inefficient retransmission of downlink transport blocks when UCI is not successfully decoded, leading to degraded performance.
Innovation Solution
Implementing a system where the gNB transmits a signaling indicator to schedule retransmission of UCI, utilizing a UCI process ID (UPID) and a timer to manage retransmissions, allowing selective retransmission of HARQ-ACK feedback based on decoding success, thereby optimizing UCI reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the UCI payload size is increased to include more HARQ-ACK feedback bits, then the coverage of downlink transmissions is improved, but the transmission reliability deteriorates due to lower SINR and higher coding rate
Solution Approach 1:
The patent segments the UCI retransmission process into multiple attempts with different resource allocations. The gNB can schedule retransmissions on different PUCCH resources with varying time-frequency characteristics, allowing the system to adapt to different reliability requirements without being constrained by a single fixed resource allocation.
Solution Approach 2:
The patent introduces dynamic resource allocation for UCI retransmissions based on channel conditions and decoding failures. The gNB can dynamically select from multiple PUCCH resources and adjust timing based on actual transmission conditions, making the system adaptable to changing network environments rather than using static resources.
2Reliability
If more frequency resources are occupied to lower the UCI coding rate, then the UCI transmission reliability is improved, but the UE transmission power efficiency deteriorates
Solution Approach 1:
The patent segments the frequency resources into multiple PUCCH resources with different characteristics. Instead of continuously occupying large frequency bandwidth, the system can use multiple smaller resource blocks spread across different frequencies and times, reducing the peak power requirement while maintaining adequate coding rate for reliability.
Solution Approach 2:
The patent moves from a single-dimensional frequency allocation approach to a multi-dimensional approach involving time, frequency, and resource type dimensions. By utilizing multiple PUCCH resources across different time slots and frequency locations, the system achieves reliability without requiring continuous high power transmission.
3Reliability
If URLLC burst transmission with high power is used in neighboring cells, then the URLLC reliability is improved, but the interference to adjacent cell UCI transmission increases
Solution Approach 1:
The patent segments the UCI transmission into multiple opportunities across different time slots and frequency resources. This segmentation allows the system to avoid simultaneous transmission with neighboring URLLC bursts by spreading UCI retransmissions across multiple PUCCH resources, reducing peak interference exposure.
Solution Approach 2:
The patent enables preliminary UCI retransmission attempts before final downlink retransmission decisions are made. By attempting UCI retransmission multiple times with different resources, the system can complete HARQ-ACK feedback before the next DL transmission, preventing interference issues from propagating to subsequent URLLC bursts.
4Productivity
If dynamic TDD is implemented in each cell, then the spectrum utilization is improved, but the cross-link interference to UCI transmission increases
Solution Approach 1:
The patent introduces dynamic resource selection for UCI retransmissions based on actual interference conditions. The gNB can monitor downlink reception quality and dynamically choose from multiple PUCCH resources, adapting the retransmission timing and frequency to avoid cross-link interference from neighboring cells while maintaining spectrum utilization efficiency.
Data Source
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AI summary
Methods and apparatuses for retransmitting uplink control information. An apparatus comprising: a receiver that receives uplink control information (UCI) from a remote unit, wherein the UCI includes hybrid automatic repeat request acknowledgement (HARQ-ACK) feedback corresponding to a plurality of downlink transmissions; a processor that decodes the UCI; and a transmitter that, in response to the UCI not being correctly decoded, transmits a first signaling to the remote unit, wherein the first signaling includes an indicator indicating that the UCI is not correctly decoded.