Composite Precoder Design for FD-MIMO Channel Feedback
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing channel state information for full-dimension MIMO systems, particularly in optimizing precoder design and feedback mechanisms to enhance radio interface efficiency and coverage amidst growing mobile data traffic.
Innovation Solution
A base station and user equipment configuration that transmits and receives Channel State Information-Reference Signals (CSI-RS) with specific antenna port configurations, extracts and determines precoder indicators to construct component and composite precoders, facilitating improved channel state reporting and precoding for enhanced communication efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional MIMO precoding is used, then system complexity is reduced, but radio interface efficiency and coverage are insufficient for growing mobile data traffic demands
Solution Approach 1:
The patent segments the precoding process into two distinct components: a first precoder (W1) selected from a codebook based on channel conditions, and a second precoder (W2) applied by the base station. This segmentation allows the UE to provide feedback on W1 while the network determines W2, distributing complexity across different entities and enabling more sophisticated overall precoding for enhanced radio interface efficiency.
Solution Approach 2:
The patent extends traditional 2D antenna arrays to 3D antenna arrays by adding an elevation dimension. This dimensional expansion enables full-dimension MIMO (FD-MIMO) systems to exploit both azimuth and elevation spatial dimensions, significantly increasing the degrees of freedom available for precoding and thereby improving radio interface efficiency and coverage area.
2Area of stationary object
If full-dimension MIMO with 3D antenna arrays is implemented, then coverage and capacity are enhanced, but channel state information management becomes more complex
Solution Approach 1:
The patent segments channel state information feedback into multiple components: channel quality information (CQI), precoder matrix indicator (PMI) for W1 selection, and rank indicator (RI). This segmented feedback approach allows the UE to report essential channel characteristics without transmitting complete channel matrices, thereby managing the complexity of 3D antenna array channel state information while still enabling effective precoding for enhanced coverage.
Solution Approach 2:
The patent implements a feedback mechanism where the UE measures channel conditions using reference signals from the 3D antenna array and returns compressed channel state information (including CQI, PMI, and RI) to the base station. This feedback loop enables the network to adapt precoding strategies to current channel conditions, maintaining optimal performance across expanded coverage areas without requiring complex real-time channel estimation at the UE.
3Productivity
If advanced precoding techniques are used, then mobile data traffic capacity increases, but feedback mechanism complexity increases
Solution Approach 1:
The patent extracts and separates the feedback burden by having the UE report only the first precoder (W1) from a codebook along with CQI and RI, while the base station determines and applies the second precoder (W2). This extraction of critical feedback elements reduces the amount of information the UE must process and transmit, thereby increasing data traffic capacity through advanced precoding without proportionally increasing feedback mechanism complexity.
Data Source
AI summary
A base station includes a transceiver configured to transmit CSI-RS according to a CSI-RS configuration comprising a first and a second numbers of antenna ports, and downlink signals comprising the CSI-RS configuration to the UE, and, receive uplink signals comprising a plurality of CSI reports from the UE, and a processor configured to extract an RI and at least PMIs from the plurality of CSI reports, determine a component precoder on the first number of antenna ports, using a first PMI and a second PMI, determine a complex number u, using a third PMI, and determine a composite precoder equal to a block matrix comprising Nr row blocks whose n-th row block is a product of un-1 and the component precoder, wherein Nr is equal to the second number of antenna ports.