LTE CRS Muting Patterns for DSS NR Spectral Efficiency
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Solution Overview
Problem
In dynamic spectrum sharing between LTE and NR, the always-on LTE Cell-specific Reference Signal (CRS) creates overhead for NR PDSCH, reducing NR spectral efficiency, as NR PDSCH has to rate match around CRS in every subframe, which is not dynamically allowed by existing 3GPP specifications.
Innovation Solution
Implement controlled LTE CRS muting by determining a maximum number of muted PRBs, setting a CRS muting pattern, and configuring a muting period and forbidden regions to balance NR spectral efficiency and LTE performance, allowing NR UEs to dynamically adjust rate matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LTE CRS is transmitted in every subframe to ensure LTE compatibility and coverage, then LTE performance is maintained, but NR spectral efficiency deteriorates due to rate matching requirements
Solution Approach 1:
The patent implements periodic CRS muting where CRS is transmitted in some subframes and muted in others according to a configured pattern. This allows NR to achieve higher spectral efficiency in muted subframes while LTE maintains compatibility in non-muted subframes, resolving the contradiction between LTE reliability and NR productivity through time-domain periodic action.
Solution Approach 2:
The patent introduces dynamic CRS muting control where the muting pattern can be configured and adjusted based on network conditions, traffic demands, and service requirements. This dynamic approach allows the system to adaptively balance LTE performance and NR spectral efficiency rather than being fixed, resolving the contradiction through configurable temporal dynamics.
2Productivity
If CRS is muted on more PRBs to improve NR spectral efficiency, then NR performance improves, but LTE coverage and reliability deteriorate
Solution Approach 1:
The patent changes the parameter of CRS transmission by introducing a muting pattern that selectively mutes CRS on specific PRBs and subframes. By controlling the density and location of muted PRBs through configurable parameters, the system can adjust the tradeoff between NR spectral efficiency improvement and LTE coverage maintenance, resolving the contradiction through parameter optimization.
Solution Approach 2:
The patent applies local quality by allowing CRS muting to be applied selectively on specific PRBs rather than uniformly across the entire bandwidth. This enables NR to gain spectral efficiency in specific frequency regions where muting is applied, while LTE maintains reliability in regions where CRS continues to be transmitted, resolving the contradiction through spatial-frequency domain differentiation.
3Adaptability or versatility
If dynamic CRS muting is implemented to improve NR spectral efficiency, then system flexibility improves, but device complexity increases due to additional configuration and coordination
Solution Approach 1:
The patent implements preliminary action by pre-configuring the CRS muting pattern through RRC signaling before actual data transmission. The gNB provides NR UEs with advance information about CRS muting patterns, maximum muted PRB counts, and other relevant parameters. This preliminary configuration reduces runtime complexity and allows UEs to efficiently perform rate matching without real-time computational burden, resolving the contradiction between adaptability and complexity.
Data Source
AI summary
Systems and method for controlled Long Term Evolution (LTE) Cell-specific Reference Signal (CRS) muting for Dynamic Spectrum Sharing (DSS) are disclosed herein. In some embodiments, a method performed by a radio access node for a DSS system serving LTE and New Radio (NR) comprises (a) determining a maximum number of CRS-muted Physical Resource Blocks (PRBs), (b) determining, based on the determined maximum number of CRS-muted PRBs, an LTE CRS rate matching pattern set for the one or more NR cells, the LTE CRS rate matching pattern set containing one or more LTE CRS rate matching patterns, (c) selecting an LTE CRS rate matching pattern from the determined LTE CRS rate matching pattern set for a User Equipment (UE), and (d) sending information that is indicative of the selected LTE CRS rate matching pattern to the UE.