DMRS Mapping Patterns for sTTI Collision Avoidance
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Solution Overview
Problem
In wireless communication systems, particularly in NR systems, there is a challenge in efficiently mapping demodulation reference signal (DMRS) data to resource elements within shortened transmission time intervals (sTTIs) without colliding with other reference signal data such as CSI-RS and CRS data, which affects channel estimation and data transmission reliability.
Innovation Solution
The solution involves defining specific DMRS mapping patterns for different types of sTTIs, where the base station selects and configures DMRS mapping patterns based on CSI-RS and CRS configurations, antenna port configurations, and subframe types to avoid collisions with other reference signal data, allowing for efficient transmission of DMRS data while enabling CSI-RS and CRS data to be carried in the same sTTIs without interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If DMRS data is mapped to resource elements in sTTI, then channel estimation quality improves, but collision with other reference signal data (CSI-RS, CRS) occurs
Solution Approach 1:
The patent segments the resource elements in sTTI by defining specific mapping patterns for DMRS that divide the frequency-time grid into non-overlapping regions. Different DMRS mapping patterns are defined for different sTTI types, creating segmented allocation schemes that prevent collision with CSI-RS and CRS while ensuring sufficient DMRS density for channel estimation.
Solution Approach 2:
The patent introduces dynamic selection of DMRS mapping patterns based on sTTI type, antenna port configuration, and reference signal configuration. The base station dynamically chooses the appropriate mapping pattern from multiple predefined options, allowing the system to adapt to different channel conditions and reference signal requirements while avoiding collisions.
2Adaptability or versatility
If multiple reference signal types are transmitted in the same sTTI, then system functionality improves, but resource element collision increases
Solution Approach 1:
The patent applies local quality by defining different DMRS mapping patterns for different local contexts (sTTI types, antenna port configurations, reference signal configurations). Each mapping pattern is optimized for its specific context, with local adjustments to resource element allocation that prevent collision with CSI-RS and CRS while maintaining appropriate DMRS density for channel estimation.
Solution Approach 2:
The patent introduces mapping pattern selection as an intermediary mechanism between DMRS transmission requirements and reference signal configurations. This intermediary layer (the selected mapping pattern) mediates the resource element allocation to ensure DMRS can coexist with CSI-RS and CRS without collision, enabling multiple reference signal types to be transmitted simultaneously.
3Reliability
If DMRS mapping patterns are configured for different sTTI types, then collision avoidance improves, but configuration complexity increases
Solution Approach 1:
The patent manages complexity through dynamic pattern selection based on predefined sTTI types and configurations. Rather than requiring complex real-time calculations, the system dynamically selects from a finite set of predefined mapping patterns based on the sTTI type and reference signal configuration, simplifying the configuration process while maintaining reliable collision avoidance.
Solution Approach 2:
The patent changes key parameters (mapping pattern index, sTTI type, antenna port configuration) to manage the complexity-collision avoidance tradeoff. By organizing mapping patterns according to these parameters and selecting based on predefined rules, the system reduces configuration complexity while ensuring collision avoidance through parameter-driven pattern selection.
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AI summary
Methods, systems, and devices for wireless communications are described for mapping demodulation reference signal (DMRS) data to resource elements (REs) within a shortened transmission time interval (sTTI) so as to avoid collision with other reference signal data that the sTTI may be configured to include, such as channel state information reference signal (CSI-RS) data, cell-specific reference signal (CRS) data, or the like. A base station may select a DMRS mapping pattern for an sTTI based on one or more factors, including a CSI-RS configuration, a CRS configuration of the sTTI, an antenna port configuration for CRS (e.g., a number of CRS ports and associated number of layers configured for CRS, such as a one port CRS having a two-layer configuration, or a two port CRS having a four-layer configuration), or a type of subframe that includes the sTTI.