Dynamic DM-RS Placement for Channel Estimation
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Solution Overview
Problem
In fast time-varying channels, placing demodulation reference signal (DM-RS) symbols at the beginning of physical downlink/shared channel (PDSCH) or physical uplink/shared channel (PUSCH) makes the estimated channel redundant or invalid for data carried near the end, leading to suboptimal channel estimation and potential errors in data decoding.
Innovation Solution
The solution involves dynamically conveying DM-RS symbols in two parts within the PDSCH/PUSCH, allowing for dynamic adjustment of the number and placement of DM-RS symbols, such as placing one at the beginning and another in the middle, to maintain accurate channel estimation throughout the transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If DM-RS symbols are placed at the beginning of PDSCH/PUSCH, then latency is reduced and channel estimation is performed early, but the estimated channel becomes redundant or invalid for data carried near the end in fast time-varying channels
Solution Approach 1:
The patent divides the channel estimation function into multiple segments by placing DM-RS symbols at multiple positions (beginning and middle/end) of the PDSCH/PUSCH transmission. This segmentation allows each DM-RS symbol to serve as a fresh reference point for subsequent data, ensuring accurate channel estimation throughout the entire transmission duration while maintaining low latency.
2Measurement precision
If DM-RS symbols are placed throughout the entire PDSCH/PUSCH transmission, then channel estimation accuracy is maintained for all data, but the overhead and complexity of the transmission structure increases
Solution Approach 1:
The patent applies local quality by strategically placing DM-RS symbols at specific positions (beginning and middle/end) rather than uniformly throughout the transmission. This targeted approach ensures that each data segment has an appropriate reference signal for channel estimation, maintaining accuracy while minimizing overhead and structural complexity compared to continuous placement.
3Reliability
If multiple DM-RS symbols are inserted in PDSCH/PUSCH, then channel estimation remains valid throughout transmission, but the overhead of reference signals increases
Solution Approach 1:
The patent implements partial action by inserting DM-RS symbols at only two critical positions (beginning and middle/end) rather than continuously throughout the transmission. This provides sufficient channel estimation coverage for fast time-varying channels while minimizing reference signal overhead, achieving the right balance between reliability and resource efficiency.
Data Source
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AI summary
DM-RS symbols may be inserted in the beginning of a subframe, or in two parts of the subframe. In one aspect, a method, a computer-readable medium, and an apparatus for dynamically conveying DM-RS information are provided. The apparatus may be a base station. The apparatus may determine the number of DM-RS symbols and/or the locations within a subframe for transmission of the DM-RS symbols. The apparatus may transmit the number of the DM-RS symbols and/or the locations within the subframe for transmission of the DM-RS symbols to a UE. In another aspect, a UE may receive the number of DM-RS symbols and/or the locations within a subframe for transmission of the DM-RS symbols from a base station. The UE may decode the DM-RS symbols from the subframe based on the number of the DM-RS symbols and/or the locations within a subframe for transmission of the DM-RS symbols.