Hybrid Multiplexing DMRS Pre-coding for LTE-A Channel Estimation
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Solution Overview
Problem
In LTE-A systems, interference between layers corresponding to different codeword streams occurs, affecting channel estimation accuracy and increasing signaling overhead due to random mapping of demodulation reference symbols.
Innovation Solution
A pre-coding method and apparatus using hybrid multiplexing demodulation reference symbols, which classify DMRS ports into groups for code division and time/frequency division multiplexing, ensuring fixed mapping relationships between data layers and DMRS ports to reduce interference and signaling overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If random mapping of demodulation reference symbols is used, then adaptability to different channel conditions is improved, but interference between layers corresponding to different codeword streams increases and channel estimation accuracy deteriorates
Solution Approach 1:
The patent segments the demodulation reference symbol ports into different groups (first group and second group) with distinct mapping rules. Layers corresponding to the same codeword stream are mapped to ports in the same group, while layers corresponding to different codeword streams are mapped to ports in different groups. This segmentation prevents interference between different codeword streams while maintaining adaptability within each group.
2Adaptability or versatility
If random mapping of demodulation reference symbols is used, then adaptability to different channel conditions is improved, but control signaling overhead increases
Solution Approach 1:
The patent applies different mapping qualities to different port groups: the first group uses fixed mapping relationships that can be predetermined and signaled with less overhead, while the second group uses random mapping for adaptability. This local differentiation reduces overall signaling overhead while preserving adaptability where needed.
3Device complexity
If common reference signal is used for all users, then system complexity is reduced, but pilot overhead increases and orthogonality cannot be realized in MU-MIMO systems
Solution Approach 1:
The patent segments the reference signal resources into user-specific demodulation reference symbols with different port mappings for different users. This allows multiple users to share the same time-frequency resources with orthogonal or near-orthogonal reference signals, reducing overall pilot overhead while maintaining low system complexity through standardized processing.
Data Source
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AI summary
Disclosed in the present invention is a pre-coding method for hybrid multiplexing demodulation reference symbol (DMRS). The method includes: determining a multiplexing relationship between DMRS ports; making layers of data transport correspond to DMRS ports with the multiplexing relationship determined; and pre-coding pilot sequences corresponding to various DMRS ports according to the relationship between the layers of data transport and the DMRS ports. Also disclosed in the present invention is a method for mapping from a layer to a multiplexing demodulation reference symbol (DMRS) and an apparatus for achieving pre-coding based on a hybrid multiplexing demodulation reference symbol (DMRS). By way of the technical solution of the present invention, interference between the layers corresponding to different codeword streams can be avoided, and the accuracy of channel estimation can be improved. At the same time, since the technical solution of the present invention employs a fixed mapping manner, the probability of random mapping is reduced and the overhead of the control signaling is also reduced.