Dynamic DMRS Density Allocation for Uplink Channel Estimation
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Solution Overview
Problem
Current communications systems face challenges in accurately estimating the channel of terminal devices due to fixed DMRS time domain densities, which can lead to either inadequate tracking of time-varying channels or excessive redundancy in time-frequency resources, particularly in scenarios like cellular Internet of Things (CIoT) where terminal device movement speeds vary.
Innovation Solution
A time-frequency resource allocation method that classifies terminal devices based on their current movement speed and configures DMRS with corresponding time domain densities, allowing for dynamic allocation of time-frequency resources to ensure accurate channel estimation and minimize redundancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed DMRS time domain density is used for all terminal devices, then the system configuration is simple, but the channel estimation accuracy deteriorates for terminal devices with different movement speeds
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed DMRS time domain density to a dynamic configuration that adapts to terminal device movement speeds. The network device determines appropriate DMRS time domain densities based on the movement speed characteristics of terminal devices, allowing the system to optimize channel estimation accuracy for different scenarios while maintaining manageable configuration complexity through automated determination.
2Quantity of substance
If a low DMRS time domain density is used, then the time-frequency resource overhead is reduced, but the channel tracking capability deteriorates for moving terminal devices
Solution Approach 1:
The patent applies local quality by assigning different DMRS time domain densities to different terminal devices based on their specific movement speed characteristics. Instead of using a uniform low density that would fail for moving devices, the system provides locally optimized DMRS configurations where terminal devices with higher movement speeds receive higher DMRS densities to maintain reliable channel tracking, while stationary devices use lower densities to minimize overhead.
3Reliability
If a high DMRS time domain density is used, then the channel tracking capability is improved, but the time-frequency resource overhead increases excessively
Solution Approach 1:
The patent applies parameter changes by adjusting the DMRS time domain density parameter according to terminal device movement speeds. The network device determines appropriate DMRS densities as parameters that match the channel variation characteristics of different terminal devices, ensuring that high densities are only used when necessary for moving devices while low densities are used for stationary devices, thereby optimizing the balance between channel tracking capability and resource overhead.
Data Source
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AI summary
Embodiments of this application provide a time-frequency resource allocation method and apparatus. The method includes: determining, by a network device, N terminal device types based on a current movement speed of a terminal device within a coverage area, where the N terminal device types are in a one-to-one correspondence with N demodulation reference signals DMRSs with different time domain densities; classifying, by the network device, available time-frequency resources into N time-frequency resource groups based on the N terminal device types, where a first DMRS in the N DMRSs is configured for a first time-frequency resource group in the N time-frequency resource groups; and sending, by the network device, resource indication information to the terminal device based on the N time-frequency resource groups. The time-frequency resource allocation method and apparatus in the embodiments of this application provide can ensure accuracy of the network device in estimating a channel of the terminal device, and can avoid excessive DMRS overheads in a time-frequency resource used by the terminal device, thereby ensuring transmission efficiency of uplink data.