Shared Demodulation Reference Signal for Multi-User MIMO
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Solution Overview
Problem
Current communication systems face challenges with signal fading and interference due to increased range and complex environments, particularly in demodulating control channels and data channels, where existing reference signals do not efficiently support beamforming and precoding for multiple-user MIMO scenarios.
Innovation Solution
The implementation of a shared demodulation reference signal (DM-RS) and user equipment-specific DM-RS, which are orthogonal or approximately orthogonal, allowing for reuse and sharing of DM-RS ports across multiple users, reducing overhead and improving system efficiency by supporting beamforming and precoding technologies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate reference signals are used for each user in multi-user MIMO, then channel demodulation accuracy is improved, but resource overhead increases
Solution Approach 1:
The patent combines reference signals from multiple users into shared resource blocks. Specifically, reference signals for different users are multiplexed in the same time-frequency resources using different spatial layers or code division, allowing multiple users to share the same reference signal resources while maintaining individual channel estimation accuracy through precoding and layer separation.
Solution Approach 2:
The patent creates universal reference signals that serve multiple users simultaneously. The same reference signal sequence and resource structure are used across multiple users, with user-specific information conveyed through precoding matrices and layer assignments rather than dedicated reference signal variations, thereby reducing overall reference signal overhead.
2Productivity
If beamforming and precoding are implemented for multiple users, then system transmission efficiency is improved, but reference signal design complexity increases
Solution Approach 1:
The patent changes the parameters of reference signals dynamically based on user conditions, including modulation order, coding rate, and resource allocation. By adjusting these parameters according to channel conditions and user requirements, the system optimizes transmission efficiency while managing reference signal complexity through standardized parameter sets and configuration procedures.
3Loss of energy
If reference signals are reused across multiple users, then resource waste is reduced, but signal interference between users increases
Solution Approach 1:
The patent applies preliminary precoding and spatial filtering to reference signals before transmission to different users. By pre-processing the reference signals with user-specific precoding matrices and selecting appropriate spatial layers, the system enables reference signal reuse across users while minimizing inter-user interference through spatial separation and orthogonalization techniques.
Data Source
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AI summary
A reference signal transmission method is provided, including: generating, by a network side device, a transmission unit, where the transmission unit includes a user equipment-specific demodulation reference signal UE-specific DM-RS, a time-frequency region for unicast control, and a user-specific data time-frequency region; and sending the transmission unit to user equipment, where the UE-specific DM-RS is reused or shared to demodulate the time-frequency region for unicast control and the user-specific data time-frequency region.