Uplink Control Information Redundancy for 5G NR Coverage
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Solution Overview
Problem
5G New Radio (NR) uplink coverage issues arise due to high-frequency wireless channel path loss, particularly in scenarios where LTE systems operate at low frequencies and NR systems at high frequencies, leading to poor coverage for uplink transmissions, especially for control information like CSI and HARQ-ACK.
Innovation Solution
The proposed solution involves techniques such as assigning a small transport block size for CSI, using simple modulation and coding schemes like QPSK, scheduling uplink control information on PUSCH through downlink control messages, and employing redundancy in uplink control information transmission across multiple slots or mini-slots to enhance coverage, allowing independent scheduling of code block groups and piggybacking HARQ-ACK information on PUSCH.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-frequency wireless channels are used for NR uplink transmissions, then spectral efficiency and data rate are improved, but path loss increases leading to poor coverage
Solution Approach 1:
The patent segments control information transmission into multiple redundant versions transmitted across different slots. Each slot carries a copy of the control information (CSI and/or HARQ-ACK), allowing the receiver to reconstruct the original message even if some slots experience fading or interference. This segmentation in time domain provides diversity gain to combat high-frequency path loss while maintaining spectral efficiency.
Solution Approach 2:
The patent employs preliminary coding and modulation of control information before transmission. Control information is encoded with redundancy (e.g., using polar codes or Reed-Solomon codes) and modulated using robust schemes (e.g., QPSK) before being transmitted across multiple slots. This preliminary preparation ensures that even under high path loss conditions, the receiver can reliably decode the control information.
2Reliability
If control information is transmitted with high reliability requirements, then demodulation success rate is improved, but transmission resources increase
Solution Approach 1:
The patent makes the PUSCH channel serve multiple functions: it simultaneously carries uplink data and uplink control information (CSI and HARQ-ACK). By multiplexing control information with data on the same physical channel, the system avoids dedicating separate resources solely for control transmissions, thereby improving reliability without proportionally increasing total resource consumption.
Solution Approach 2:
The patent creates multiple copies of control information transmitted across different time slots rather than using complex high-rate coding schemes. Each slot contains a redundant version of the control message, allowing the receiver to select or combine copies to achieve reliable demodulation. This copying approach provides high reliability with relatively low overhead compared to alternative methods.
3Device complexity
If simple modulation and coding schemes are used for uplink control information, then implementation complexity is reduced, but transmission capacity decreases
Solution Approach 1:
The patent compensates for the low capacity of simple modulation schemes by introducing a time dimension through multi-slot transmission. Instead of using complex high-order modulation to increase per-symbol capacity, the system transmits the same control information across multiple time slots with simple robust modulation (e.g., QPSK). The aggregate capacity across multiple slots provides sufficient throughput while maintaining low implementation complexity.
Data Source
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AI summary
Methods, systems, and devices related to transmissions of control information to enhance channel coverage are disclosed. In one exemplary aspect, a method for wireless communication includes receiving, from a base station, a control message for scheduling a transmission of control information on a physical channel based on a transmission mode of the physical channel, the control information comprising at least channel state information; and transmitting, based on the control message, one or more redundant versions of the control information on the physical channel using a plurality of adjacent slots or mini-slots in time domain.