Two-Part Feedback for TDD MIMO Precoding Reciprocity Mismatch
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Solution Overview
Problem
In wireless networks like 5G or NR, the mismatch between uplink and downlink channels due to hardware differences and SAR control leads to incomplete reciprocity, causing performance loss in downlink MIMO precoding.
Innovation Solution
A two-part feedback information transmission system for client devices, where the first part indicates a quantization range via a higher layer and the second part provides quantized values via a physical layer, allowing low overhead and improved downlink MIMO precoding in TDD-based communication systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If feedback information is transmitted via physical layer only, then transmission speed is fast, but overhead becomes excessive
Solution Approach 1:
The feedback information is divided into two parts: Part 1 (quantization range indication) transmitted via non-physical layer and Part 2 (quantized values) transmitted via physical layer. This segmentation allows the system to benefit from both higher-layer flexibility and physical-layer speed while reducing overall overhead through selective transmission paths.
2Device complexity
If quantization range is fixed, then system complexity is reduced, but adaptability to different scenarios deteriorates
Solution Approach 1:
The quantization range is made dynamic through Part 1 feedback that indicates the quantization range based on current channel conditions. This allows the system to adapt to different scenarios (varying channel power, different antenna configurations) while maintaining manageable complexity through standardized quantization procedures.
Data Source
AI summary
Devices, methods and computer readable medium for two-part feedback information transmission in wireless communications are provided. The two-part feedback information transmission is adopted, e.g., for improved downlink multiple-input and multiple-output (MIMO) precoding in time-division duplex (TDD)-based communication systems. The feedback information transmission allows compensating for adverse effects of incomplete UL-DL reciprocity for DL MIMO precoding caused by mismatched DL and UL channel measurements. The feedback information transmission being two-part allows low overhead for the feedback information.