Partial DMRS Transmission for Rate-Matched PDSCH
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Solution Overview
Problem
The existing 3GPP Release 15 5G New Radio specification requires the entire downlink shared channel (PDSCH) demodulation reference signal (DMRS) to be transmitted, which restricts network flexibility and can negatively impact channel estimation and noise measurement for user equipment (UE), especially during PDSCH rate matching.
Innovation Solution
A method and apparatus for partial transmission of PDSCH DMRS are introduced, where the number and type of rate matching patterns that allow partial DMRS transmission are determined based on the UE's radio resource control state and PDSCH characteristics, with explicit indication of UE capabilities, enabling flexible allocation and decoding of downlink signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the entire DMRS is transmitted for PDSCH, then the channel estimation and noise measurement for UE are maintained, but the network flexibility is restricted
Solution Approach 1:
The DMRS transmission is segmented into multiple patterns (first pattern and second pattern), where the first pattern is transmitted in rate-matched regions and the second pattern is transmitted in non-rate-matched regions. This segmentation allows the network to flexibly select which pattern to use based on scheduling requirements while ensuring reliable channel estimation through the always-transmitted first pattern.
Solution Approach 2:
The invention introduces dynamic selection between different DMRS transmission patterns based on rate matching conditions. The network can dynamically choose to transmit only the first DMRS pattern when rate matching is applied, or transmit both first and second patterns when rate matching is not applied, thereby adapting to different scheduling scenarios while maintaining estimation reliability.
2Adaptability or versatility
If the entire DMRS is transmitted regardless of PDSCH rate matching, then the UE's channel estimation and noise measurement are supported, but network flexibility is restricted
Solution Approach 1:
The invention extracts the essential channel estimation function into the first DMRS pattern that is always transmitted, while the second DMRS pattern is conditionally transmitted based on rate matching conditions. This extraction ensures that critical reference signal information is never lost while allowing flexibility in transmitting additional reference signals when beneficial.
3Adaptability or versatility
If partial DMRS transmission is allowed, then network flexibility is improved, but the UE's channel estimation interpolation behavior may be negatively impacted
Solution Approach 1:
The invention provides beforehand cushioning for potential channel estimation degradation by ensuring the first DMRS pattern is always transmitted in rate-matched regions. This creates a reliable baseline for channel estimation that compensates for the reduced information available when the second pattern is not transmitted, thereby maintaining measurement precision despite partial transmission.
Data Source
AI summary
An apparatus and method are provided for partial transmission of a PDSCH DMRS due to PDSCH RM. The method includes determining, by the UE, whether a downlink received from a base station is rate matched; and in response to determining that the downlink is rate-matched, determining, by the UE, that a rate matching pattern of the downlink is applicable for partial transmission of a reference signal, and decoding, by the UE, the downlink with a partial transmission of the reference signal.