Partial Codebook Reshaping for 2D Antenna Array Precoding
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Solution Overview
Problem
Current precoding techniques for two-dimensional antenna arrays face challenges in efficiently adapting codebooks to varying radio conditions without wasting processing resources or generating excessive signaling overhead, particularly in LTE Release 13 with limited predetermined codebooks.
Innovation Solution
The proposed solution involves using a main codebook represented as a Kronecker product of two or more factors, where one codebook is predetermined and not dynamically adapted, while the other codebook is configurable, allowing partial adaptation to optimize precoding based on local radio conditions without changing the entire codebook, thus reducing processing and signaling overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed predetermined codebook is used for two-dimensional antenna arrays, then device complexity and signaling overhead are reduced, but adaptability to varying radio conditions deteriorates
Solution Approach 1:
The codebook is segmented into multiple codebook types (e.g., codebook type 1, type 2, type 3) each optimized for different antenna array configurations. The transmitting node segments the codebook selection process by determining which codebook type best matches the current antenna array geometry, thereby achieving adaptability without requiring a single overly complex codebook structure.
Solution Approach 2:
The codebook selection becomes dynamic rather than static. The transmitting node dynamically determines the appropriate codebook type based on real-time antenna array configuration and radio conditions. This dynamic adaptation allows the system to switch between different codebook structures as needed, resolving the contradiction between using a fixed simple codebook and needing adaptability to varying conditions.
2Adaptability or versatility
If codebook adaptation is implemented for local radio conditions, then adaptability improves, but processing resources and signaling overhead increase
Solution Approach 1:
The invention applies local quality by determining codebook type based on local antenna array characteristics and local radio conditions rather than implementing global codebook adaptation. Each transmitting node independently determines the appropriate codebook type for its specific local environment, achieving necessary adaptability without the overhead of centralized or extensive processing.
Solution Approach 2:
The system changes parameters (codebook type selection) based on measured radio conditions and antenna configuration. By monitoring parameters such as antenna array geometry and channel characteristics, the system selectively changes the codebook type parameter to match current conditions, achieving adaptability through parameter adjustment rather than full codebook reconfiguration.
3Manufacturing precision
If reference signals and CSI feedback are transmitted for precoder selection, then precoding accuracy improves, but transmission overhead increases
Solution Approach 1:
The system applies partial action by transmitting reference signals and collecting CSI feedback only for the selected codebook type rather than for all possible codebooks. This partial measurement approach maintains sufficient precoder selection accuracy for the current radio conditions while significantly reducing the quantity of reference signals and feedback data compared to exhaustive codebook evaluation.
Data Source
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Figure 3
Figure 4A~4D
AI summary
A transmitting radio node (10) precodes a transmission from an antenna array, which includes antenna elements arranged along at least two axes, using a main codebook which is representable as a Kronecker product of a first codebook and a second codebook, where the first codebook comprises predetermined sub-precoders and the second codebook comprises configurable sub-precoders. A receiving radio node (20) may benefit from adaptive beamforming made possible by the configurability of the main codebook, while still using a stable format, which remains valid also after reconfiguration, for the exchange of reference signals and corresponding feedback information.