DMRS Port Pattern Extension for Non-Orthogonal Uplink Access
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Solution Overview
Problem
The current 5G NR systems can only support a maximum of 12 DeModulation Reference Signal (DMRS) orthogonal ports, which is insufficient for non-orthogonal multiple access transmission in the uplink scheduling-free scenario, requiring a higher number of ports such as 24 or 48 to ensure effective UE activation detection and channel estimation.
Innovation Solution
A data transmission method and device that determines and uses a DMRS orthogonal port pattern with a quantity greater than 12, specifically for CP-OFDM and DFT-s-OFDM waveforms, by implementing different DMRS orthogonal ports at orthogonal frequency-domain positions using Frequency Division Multiplexing (FDM) and cyclic shifts of Zadoff-Chu sequences, to support non-orthogonal multiple access transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the maximum number of DMRS orthogonal ports is limited to 12 for CP-OFDM and 8 for DFT-s-OFDM waveforms, then the system complexity and resource overhead are controlled, but the non-orthogonal multiple access transmission requirement in uplink scheduling-free scenario cannot be met
Solution Approach 1:
The patent extends the DMRS orthogonal port indexing from the traditional 0-11 range to a higher range (e.g., 24 or 48 ports), effectively adding a new dimension to the port space. This allows the system to support more simultaneous users in uplink scheduling-free scenarios while maintaining backward compatibility with existing waveforms through proper mapping of the extended port indices to available reference signal resources
Solution Approach 2:
The patent changes the parameter of DMRS orthogonal port quantity from the conventional limit (12 for CP-OFDM, 8 for DFT-s-OFDM) to higher values (24 or 48). This parameter change enables support for non-orthogonal multiple access by allowing more reference signal ports to be allocated, thereby accommodating more users simultaneously in the uplink scheduling-free scenario
2Productivity
If the number of DMRS orthogonal ports is increased to 24 or 48 for uplink scheduling-free scenario, then the non-orthogonal multiple access transmission is supported, but the resource overhead and signal interference increase
Solution Approach 1:
The patent segments the extended DMRS orthogonal ports into different groups or layers, where each port is allocated to specific users or transmission streams. This segmentation allows for organized resource management and reduces interference by ensuring that ports with similar characteristics are properly separated, thereby supporting higher user capacity while controlling signal interference
Solution Approach 2:
The patent introduces proper mapping relationships as intermediaries between the extended DMRS port indices and the physical reference signal resources. This intermediary mapping layer enables the system to accommodate 24 or 48 logical ports while efficiently utilizing the available physical resources, thereby reducing resource overhead and managing interference through optimized resource allocation
Data Source
AI summary
The present application describes a data transmission method and device, which are used to better support non-orthogonal multiple access data transmission in an uplink grant-free scenario. The data transmission method includes determining a demodulation reference signal (DMRS) orthogonal port pattern of an uplink data channel, there being more than 12 DMRS orthogonal ports; and using the DMRS orthogonal port pattern to carry out data transmission.