DMRS-Based MCS Adaptation for Downlink Channel Feedback
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Solution Overview
Problem
Existing wireless communication systems, particularly in 5G NR networks, face inefficiencies in channel condition estimation and modulation and coding scheme (MCS) selection due to limitations in Channel State Information Reference Signal (CSI-RS) reporting, leading to suboptimal data transmission and increased retransmissions.
Innovation Solution
Utilizing Demodulation Reference Signal (DMRS) for real-time channel condition feedback, allowing user equipment (UE) to report signal-to-noise ratio (SNR) and Hybrid Automatic Repeat Request (HARQ) indicators, enabling the base station to adjust MCS and transmission parameters dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If periodic CSI-RS transmissions and aperiodic reports are used for channel reporting, then channel condition information can be obtained, but bandwidth for data is reduced and system throughput is reduced
Solution Approach 1:
The patent extracts the channel estimation function from dedicated CSI-RS resources and implements it using DMRS that are already present in the data transmission. By reusing the DMRS for channel estimation purposes, the system eliminates the need for separate CSI-RS resources, thereby extracting the harmful element (dedicated reference signals) while preserving the useful function (channel condition measurement).
Solution Approach 2:
The DMRS is given multiple functions: it serves both as a demodulation reference signal for data reception and as a channel state information reference signal for channel quality measurement. This multi-functionality allows the system to obtain channel condition information without adding dedicated CSI-RS resources, thus maintaining data bandwidth and throughput while improving measurement accuracy.
2Measurement precision
If periodic CSI-RS transmissions are used for channel reporting, then channel condition information can be obtained, but downlink resources are consumed
Solution Approach 1:
The DMRS transmitted in the downlink serves dual purposes: enabling data demodulation and providing channel state information for feedback. By making the downlink reference signal multi-functional, the system eliminates the need for additional dedicated CSI-RS resources, thereby maintaining downlink resource efficiency while ensuring accurate channel condition measurement.
Solution Approach 2:
The downlink transmission itself provides the channel estimation information needed for uplink scheduling decisions. The DMRS embedded in the downlink data transmission automatically serves as the reference for the UE to measure and report channel conditions, making the system self-sufficient without requiring separate resource allocations for channel sounding.
3Quantity of substance
If channel condition feedback is implemented using existing uplink channels, then additional downlink resources are not required, but the uplink channel must support both data and control information
Solution Approach 1:
The patent merges the channel state information feedback with the uplink data transmission by utilizing the Physical Uplink Shared Channel (PUSCH). Instead of using separate control channels, the channel quality measurements derived from DMRS are multiplexed together with uplink data, thereby consolidating control and data planes and reducing overall system complexity despite the dual-use requirement.
Data Source
AI summary
Demodulation reference signal (DMRS) based modulation and coding scheme (MCS) determination in downlink allocation is described herein. A method as described herein can include transmitting, by a first device comprising a processor, a first transmission to a second device via a downlink channel, wherein the first transmission utilizes a first MCS and comprises a DMRS; receiving, by the first device, a second transmission from the second device in response to the transmitting of the first transmission, wherein the second transmission comprises channel quality data, indicative of a channel quality of the downlink channel as estimated by the second device based on the DMRS, and a hybrid automatic repeat request (HARQ) data corresponding to the first transmission; and adjusting, by the first device, the first MCS based on the channel quality data, resulting in a second MCS to be applied to a third transmission to the second device.