Interpolated Subband Precoder Matrix for MU-MIMO Quantization Error Reduction
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Solution Overview
Problem
Fourth-Generation (4G) LTE networks face significant quantization errors in closed-loop multi-user multiple-input multiple-output (MU-MIMO) transmissions due to limited precoder selection, which is not ideal for current channel conditions, and increasing the codebook size to reduce these errors requires substantial additional feedback.
Innovation Solution
The implementation of a method that uses two precoding-matrix indicators (PMIs) associated with the same subband to compute a single subband precoder matrix, reducing quantization error without the need for a larger codebook, by interpolating precoding matrices and weighting their vectors to generate a more accurate precoder for MU-MIMO transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a larger codebook is used to reduce quantization error, then precoding accuracy is improved, but feedback overhead and system complexity increase significantly
Solution Approach 1:
The codebook is divided into multiple subcodebooks, each handling specific spatial directions or beam types. Instead of selecting one precoder from a large codebook, the system segments the precoding process into multiple smaller selections, reducing feedback overhead while maintaining accuracy through coordinated use of subcodebook selections
Solution Approach 2:
The patent introduces a new dimension to codebook structure by organizing precoders in terms of spatial layers, beam types, and directional components. This multi-dimensional organization allows the system to achieve fine-grained precoding control without requiring a single large codebook, as each dimension contributes independently to the overall precoding accuracy
2Measurement precision
If a larger codebook is used to reduce quantization error, then precoding accuracy is improved, but device complexity increases
Solution Approach 1:
The codebook is divided into multiple subcodebooks, each handling specific spatial directions or beam types. Instead of selecting one precoder from a large codebook, the system segments the precoding process into multiple smaller selections, reducing feedback overhead while maintaining accuracy through coordinated use of subcodebook selections
Solution Approach 2:
The patent introduces a new dimension to codebook structure by organizing precoders in terms of spatial layers, beam types, and directional components. This multi-dimensional organization allows the system to achieve fine-grained precoding control without requiring a single large codebook, as each dimension contributes independently to the overall precoding accuracy
3Loss of information
If limited precoder selection is used, then feedback overhead is reduced, but quantization error increases
Solution Approach 1:
The codebook is divided into multiple subcodebooks, each handling specific spatial directions or beam types. Instead of selecting one precoder from a large codebook, the system segments the precoding process into multiple smaller selections, reducing feedback overhead while maintaining accuracy through coordinated use of subcodebook selections
Solution Approach 2:
The patent introduces a new dimension to codebook structure by organizing precoders in terms of spatial layers, beam types, and directional components. This multi-dimensional organization allows the system to achieve fine-grained precoding control without requiring a single large codebook, as each dimension contributes independently to the overall precoding accuracy
Data Source
AI summary
Embodiments of an enhanced Node B (eNB) and method for precoding with reduced quantization error are generally described herein. In some embodiments, first and second precoding-matrix indicator (PMI) reports may be received on an uplink channel and a single subband precoder matrix may be interpolated from precoding matrices indicated by both the PMI reports. Symbols for multiple-input multiple output (MIMO) beamforming may be precoded using the interpolated precoder matrix computed for single subband for a multiple user (MU)-MIMO downlink orthogonal frequency division multiple access (OFDMA) transmission. In some embodiments, each of the first and second PMI reports includes a PMI associated with a same subband that jointly describes a recommended precoder.