MIMO Precoder Feedback Multiplexing for LTE-A Terminals
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Solution Overview
Problem
LTE-A systems face challenges in accurately generating precoding weights for downlink MIMO transmission due to limitations in feeding back precoders selected from two codebooks, W1 and W2, which affects data rate and spectral efficiency.
Innovation Solution
A mobile terminal apparatus and radio communication method that select and multiplex subband and wideband second PMIs from a second codebook on subframes, transmitting these through a physical uplink control channel to a radio base station, enabling the generation of essential precoding weights for downlink MIMO transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If precoders are selected from two codebooks W1 and W2 for downlink MIMO transmission, then data rate and spectral efficiency can be improved, but the complexity of feeding back precoders accurately increases
Solution Approach 1:
The feedback of precoders is segmented into two parts: wideband second PMI (w2) and subband second PMI (s2). The wideband component captures frequency-independent characteristics, while the subband component captures frequency-selective variations. This segmentation allows accurate precoder representation without requiring complete feedback of all codebook parameters, thus improving data rate while managing feedback complexity.
Solution Approach 2:
The invention introduces a dimensional decomposition approach by separating the precoder feedback into wideband and subband dimensions. Instead of feedback in a single frequency domain, the system uses two-dimensional feedback structure (frequency bands × precoder components), where wideband PMI provides coarse frequency-independent information and subband PMI provides fine frequency-selective information, achieving accurate precoding with reduced overall feedback overhead.
2Measurement precision
If complete precoder information is fed back through physical uplink control channel, then precoding weight accuracy is improved, but the signaling overhead and resource consumption increase
Solution Approach 1:
The invention extracts only the essential components of precoder information needed for accurate downlink MIMO transmission. Instead of feeding back complete precoder matrices or all codebook parameters, the system extracts and feeds back only the wideband second PMI and subband second PMI, which are the critical components for generating accurate precoding weights. This extraction approach maintains precoding accuracy while significantly reducing signaling overhead.
Solution Approach 2:
The system implements partial feedback action by transmitting only the necessary PMI components (wideband and subband second PMI) rather than complete precoder information. This partial feedback provides sufficient accuracy for precoding weight generation without the excessive resource consumption of complete precoder feedback, achieving an optimal balance between precision and overhead.
Data Source
AI summary
The present invention provides a mobile terminal apparatus and a radio communication method which can feed back precoders that are essential to generate precoding weights in downlink MIMO transmission. With the present invention, in the first mode to feed back subband second PMIs that are selected per bandwidth part through a physical uplink control channel, a subband second PMI and a wideband second PMI are selected from a second codebook, the subband second PMI and the wideband second PMI are multiplexed on a subframe, and the multiplex signals is transmitted to a radio base station apparatus through the above physical uplink control channel.