DMRS Mapping Rule for 5G Ultra-Low Delay
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Solution Overview
Problem
The existing DMRS mapping in LTE-A systems is not compatible with the new frame structure required for low-delay scenarios in 5G NR systems, particularly in ultra-low delay key indicator scenarios where faster interaction between uplink and downlink transmissions is necessary.
Innovation Solution
Centrally mapping demodulation reference signals on resource units with their location ahead of data signals, allowing for efficient data demodulation in low-delay frame structures, and configuring the quantity of time-frequency units carrying each reference signal based on active antenna ports and channel quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If block pilot form DMRS is distributed in each PRB pair with mapping including last symbol, then channel estimation can be performed for each transmit antenna, but it cannot meet the requirement of new frame structure with ultra-low delay where downlink transmission demodulation decoding must be completed before uplink feedback
Solution Approach 1:
The reference signal is mapped to a resource element in the first part of the physical resource block, which is transmitted before the data signal. This preliminary positioning of the reference signal allows the receiver to perform channel estimation earlier, enabling demodulation decoding to be completed before uplink feedback in ultra-low delay scenarios, thus resolving the contradiction between speed and frame structure compatibility.
2Productivity
If reference signal is mapped ahead of data signal in first part of resource unit, then data demodulation efficiency is enhanced for low-delay scenarios, but resource allocation complexity increases
Solution Approach 1:
The physical resource block is divided into a first part and a second part, with the reference signal mapped to a resource element in the first part and the data signal mapped to resource elements in the second part. This segmentation clearly separates reference signal resources from data resources, simplifying resource allocation management while enabling efficient demodulation in low-delay scenarios.
Data Source
AI summary
A reference signal transmission method, a related device, and a communications system are provided. The method includes: determining a time-frequency resource occupied by at least one reference signal in at least one resource unit, where each of the at least one resource unit includes a first part and a second part, the first part and the second part occupy different symbols, any symbol occupied by the first part is in front of any symbol occupied by the second part; and sending the reference signal by using the determined time-frequency resource. According to the embodiments of the present invention, a receive end device can be more time-effective during data demodulation.