CSI-RS Overhead Reduction in MU-MIMO Systems
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Solution Overview
Problem
In wireless communication systems, particularly in LTE systems with increased numbers of transmitting antennas, there is a need to reduce the overhead of channel state information reference signals (CSI-RS) while ensuring effective CSI feedback to support multi-user multiple input multiple output (MU-MIMO) transmission.
Innovation Solution
The method involves configuring multiple non-zero power (NZP) CSI-RS resources and combining their measurement results to reduce overhead, and using a combination of NZP and zero power (ZP) CSI-RS resources to efficiently measure channel and interference characteristics, with the UE assuming reference PDSCH transmitted power based on the energy ratio of PDSCH to NZP CSI-RS energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of transmitting antennas is increased to support MU-MIMO transmission, then the data transmission capacity and spectral efficiency are improved, but the overhead of CSI-RS resources increases significantly
Solution Approach 1:
The patent segments the CSI-RS resources by dividing the antenna array into multiple groups, where each group is associated with a separate CSI-RS resource. This allows the system to support a large number of transmitting antennas (e.g., 64 antennas) without requiring a proportional increase in CSI-RS overhead, as each antenna group can be measured using dedicated reference signals. The segmentation enables efficient resource utilization while maintaining high data transmission capacity for MU-MIMO operations.
2Measurement precision
If more CSI-RS resources are allocated to measure channel states for multiple antennas, then the CSI feedback accuracy is improved, but the resource overhead and system complexity increase
Solution Approach 1:
The patent implements multi-functionality by enabling each antenna group to share a common CSI-RS resource when the group size and configuration allow. This universal approach means that a single CSI-RS resource can serve multiple antenna groups simultaneously, reducing the total number of required reference signals. The system dynamically determines whether to allocate dedicated or shared resources based on configuration parameters, thereby maintaining measurement precision while reducing system complexity and resource overhead.
3Measurement precision
If dedicated CSI-RS resources are assigned to each antenna group, then the channel measurement accuracy is improved, but the resource overhead increases
Solution Approach 1:
The patent introduces dynamic resource allocation where the system can flexibly switch between dedicated and shared CSI-RS resource configurations based on operational conditions. The network can configure antenna groups to use dedicated resources when high measurement accuracy is required, and switch to shared resources when resource overhead needs to be reduced. This dynamic adaptability allows the system to optimize the balance between measurement precision and resource consumption according to real-time requirements.
Data Source
AI summary
The present disclosure provides a data transmission method. A UE receives CSI-RS configuration signaling from a base station, measuring and reporting CSI according to the CSI-RS configuration signaling. The UE receives scheduling signaling from the base station, and receives downlink data according to the scheduling signaling. The method provides a way of measuring and feeding back CSI with reduced CSI-RS overhead. The method can configure DMRS ports in a flexible manner. Therefore, performances of MU-MIMO can be optimized.