DMRS Sequence Multiplexing for 5G Interference Mitigation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current 5G NR DMRS configurations face challenges in efficiently multiplexing DMRS ports without increasing overhead, and they lack flexibility in using various CDM sequences, which affects interference mitigation and peak-to-average-power ratio.

Innovation Solution

The proposed method generates a DMRS comprising one or more ports by mapping bit sequences to real- or complex-valued sequences and using orthogonal or unitary matrices for code-division multiplexing, allowing for flexible CDM sequence size and interleaved mapping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If current 5G NR DMRS configurations are used, then the system provides basic demodulation functionality, but the number of multiplexed DMRS ports is limited and overhead increases

Engineering Contradiction:

Improvenumber of multiplexed DMRS portsVSAvoidDMRS configuration complexity

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent changes the parameter of CDM sequence length from fixed (L=2) to variable (L can be 2, 4, 6, 8, or other even numbers), allowing flexible multiplication of DMRS ports. By adjusting the CDM sequence length parameter, the system can support different numbers of multiplexed ports without increasing time-frequency resource overhead, thus resolving the contradiction between quantity and complexity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces dynamic configuration of CDM sequences where the sequence length and mapping patterns can be adjusted based on transmission requirements. The system dynamically selects appropriate CDM sequence lengths and mapping types (interleaved or non-interleaved) to optimize port multiplexing capacity while maintaining manageable configuration complexity.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If fixed CDM sequence length is used, then the mapping process is simple, but the flexibility in sequence selection and interference mitigation is reduced

Engineering Contradiction:

Improveflexibility in CDM sequence selectionVSAvoidCDM sequence mapping complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements dynamic CDM sequence selection where the sequence length L and mapping patterns can be adjusted based on transmission requirements. The system dynamically selects appropriate CDM sequence lengths and mapping types (interleaved or non-interleaved) to optimize port multiplexing capacity while maintaining manageable configuration complexity.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

Inventive Principle:

Principle #35Parameter changes

3Reliability

If traditional DMRS mapping is used, then the implementation is straightforward, but the peak-to-average-power ratio is not preserved

Engineering Contradiction:

Improvepeak-to-average-power ratio preservationVSAvoidmapping process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces traditional mechanical mapping approaches with mathematical transformations using orthogonal or unitary matrices. By substituting the mapping process with these mathematical operations, the system preserves the peak-to-average-power ratio while maintaining implementation feasibility through standardized mathematical computations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS20250184055A1Enhancement of Code-Division Multiplexing Design for Demodulation Reference Signals

Publication Date: 2025.06.05 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV

AI summary

A communication device for generating a demodulation reference signal (DMRS) may be configured to generate and map a bit sequence to a first sequence and also obtain a second sequence for a port of the DMRS. The first and second sequences may be mapped to DMRS resource elements of a physical channel for the port. To map the first and second sequences, the communication device may be configured to multiply entries of the first sequence, element-by-element, with entries of the second sequence. A resulting real- or complex-valued symbol or baseband amplitude sequence may be mapped to a subset of DMRS resource elements for port from a set of resource elements associated with the DMRS in one or more physical resource blocks (PRBs) of the physical channel. The subset of DMRS resource elements associated with port may all be present in a single PRB or in at least two different PRBs.