DM-RS Mapping With OCC Multiplexing for Multi-Layer NR Demodulation
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Solution Overview
Problem
The existing 3GPP NR system lacks methods for configuring demodulation reference signals (DMRS) that support an increased number of layers and antenna ports, particularly in various operation modes, including Multi User-Multiple Input Multiple Output (MU-MIMO) scenarios.
Innovation Solution
A method for dynamically signaling pattern configuration information of DMRS, supporting an increased number of layers and antenna ports, using orthogonal cover codes (OCC) for multiplexing DMRS antenna ports, and defining DMRS mapping in time-frequency resources to enhance DMRS patterns for both Single User (SU)-MIMO and MU-MIMO in the NR system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of layers and antenna ports is increased to support more users and higher data rates, then the system capacity and throughput are improved, but the complexity of DMRS configuration and signaling increases
Solution Approach 1:
The patent segments the DMRS configuration into multiple independent parameters including pattern type, number of ports, scrambling IDs, and resource element mappings. Each parameter can be independently configured and signaled, allowing the system to support increased layers and antenna ports while managing complexity through modular parameterization rather than monolithic configuration
Solution Approach 2:
The patent introduces additional configuration dimensions such as pattern type (type 1 or type 2), multiple scrambling ID spaces, and flexible resource element offset parameters. These additional dimensions provide more granular control over DMRS behavior, enabling the system to accommodate increased capacity requirements while maintaining manageable signaling overhead through structured parameter organization
2Reliability
If DMRS is mapped to support more antenna ports and layers, then the demodulation capability for multi-user MIMO is improved, but the overhead in time-frequency resources increases
Solution Approach 1:
The patent enables partial DMRS mapping where not all antenna ports require full DMRS sequences. Through parameters like dmrs-Type, dmrs-Port-Indices, and scrambling ID configurations, the system can allocate DMRS resources selectively based on actual transmission needs, providing sufficient demodulation capability for active ports while avoiding unnecessary overhead for inactive or shared ports
Solution Approach 2:
The patent employs multiple configurable parameters including dmrs-Scrambling-ID1 and dmrs-Scrambling-ID2, resourceElementOffset, and pattern type to dynamically adjust DMRS resource allocation. These parameter changes allow flexible adaptation of DMRS overhead to match the actual number of active layers and antenna ports, optimizing the balance between demodulation capability and resource efficiency
3Adaptability or versatility
If different DMRS patterns are configured for different terminals, then the adaptability to various terminal scenarios is improved, but the signaling overhead for pattern configuration increases
Solution Approach 1:
The patent creates a universal DMRS configuration framework where a single set of parameters (dmrs-Type, dmrs-Port-Indices, scrambling IDs, resource element offsets) serves multiple terminal scenarios including SU-MIMO, MU-MIMO, different mobility conditions, and various bandwidth configurations. This multi-functional parameter set eliminates the need for separate configuration schemes for different scenarios, reducing signaling overhead while maintaining broad adaptability
Solution Approach 2:
The patent enables preliminary configuration of DMRS parameters through higher-layer signaling (RRC configuration) where terminal capability and scenario requirements are assessed in advance. The base station pre-configures appropriate DMRS parameters including pattern type, port indices, and scrambling IDs based on terminal characteristics before actual data transmission, reducing the need for dynamic signaling adjustments and minimizing overhead during time-critical transmission phases
Data Source
Figure 1(a)~1(d)
Figure 2(a)~3a
Figure 3b~3c
AI summary
Methods, apparatuses, and systems described herein generally relate to a reference signal generation and mapping. For example, a method comprises determining a first set of antenna ports for a demodulation reference signal (DM-RS) transmission; determining, based on the first set, a frequency index associated with four adjacent resource elements, wherein the four adjacent resource elements correspond to two adjacent symbols in a time axis and to two adjacent subcarriers in a frequency axis; generating, based on a first orthogonal cover code and a second orthogonal cover code, a DM-RS associated with the first set of antenna ports; and transmitting, via a mapping to the four adjacent resource elements, the DM-RS associated with the first set of antenna ports.