Joint Rank Indicator Feedback in Full-Dimension MIMO Systems
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Solution Overview
Problem
In full-dimension multi-antenna systems using 2D planar array antennas, there is an inconsistency in the joint rank indicator (JRI) reported between the base station and user equipment, leading to inefficiencies in channel state information sharing and increased overhead due to reference signals and feedback processes.
Innovation Solution
A method is introduced to estimate and transmit a consistent joint rank indicator (JRI) using precoding matrix indicators (PMIs) and rank indicators (RIs) for each domain channel, allowing for efficient channel estimation and data transmission by determining a zero-layer mapper and precoder based on feedback information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate domain channels are used for 3D beamforming in FD-MIMO systems, then beamforming capability in both azimuth and elevation domains is improved, but inconsistency in joint rank indicator between base station and user equipment occurs
Solution Approach 1:
The channel is segmented into separate domain channels (azimuth and elevation domains) for independent processing and feedback. Each domain channel has its own precoding matrix indicator and rank indicator, allowing independent optimization while maintaining overall system consistency through the relationship JR ≤ min(JR1, JR2).
Solution Approach 2:
The user equipment feeds back precoding matrix indicators and rank indicators for each domain channel to the base station. The base station uses this feedback to determine the joint rank indicator, ensuring both sides have consistent information for data transmission while adapting to 3D channel characteristics.
2Productivity
If multiple antenna arrays are deployed to support 3D beamforming, then frequency efficiency and multi-user MIMO performance are improved, but overhead due to reference signals and feedback processes increases
Solution Approach 1:
Instead of requiring complete channel state information for all antenna elements, the system uses partial feedback through domain-specific precoding matrix indicators and rank indicators. This partial action approach reduces feedback overhead while maintaining sufficient information for effective 3D beamforming and multi-user MIMO operations.
3Measurement precision
If domain-specific precoding is applied for separate channel estimation, then channel estimation accuracy is improved, but complexity of precoder determination increases
Solution Approach 1:
The precoding process is segmented into domain-specific operations where separate precoding matrix indicators are determined for azimuth and elevation domains. This segmentation allows independent channel estimation and precoder selection in each domain, improving accuracy while managing complexity through modular processing.
Solution Approach 2:
The system performs preliminary channel estimation and precoder determination in separate domains before combining results for joint transmission. This preliminary action in each domain simplifies the overall complexity by breaking down the complex 3D channel into manageable 2D components that can be processed independently.
Data Source
AI summary
Disclosed are feedback and transmission devices and methods in full-dimension multi-antenna systems using two-dimensional (2D) planar array antennas, wherein a UE estimates channel states each corresponding to a respective one of multiple domain channels by a reference signal received from a base station, and obtains precoding matrix indicators (PMIs) each corresponding to a respective one of the multiple domain channels and rank indicators (RIs) each corresponding to a respective one of the multiple domain channels based on the estimated channel states. The UE may determine a joint rank indicator (JRI) using the obtained PMIs and the RIs and transmit feedback information containing the determined JRI to the base station.