Antenna Switchover for MIMO Feedback Reduction
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Solution Overview
Problem
In multi-user MIMO systems, existing methods face challenges in improving transmission characteristics and reducing feedback information while achieving diversity effects, as they often result in insufficient channel gain changes during retransmissions, limiting the effectiveness of hybrid ARQ schemes.
Innovation Solution
The proposed solution involves a receiving apparatus and method that uses a combining and quantizing unit to generate a combination channel vector, selects a quantization vector, and feeds its index back to the transmitting apparatus, while the transmitting apparatus employs a repeat controlling unit to determine retransmissions and calculates a beamforming matrix based on the feedback, allowing for antenna switchover and improved beamforming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reception side uses MMSE detection method to calculate SINR and feeds back to transmission side, then transmission characteristics can be improved, but the amount of feedback information increases
Solution Approach 1:
The patent extracts only the essential channel state information (quantization vector index) from the complete channel matrix, feeding back only this compressed representation to the transmission side. This extraction approach maintains the ability to improve transmission characteristics while significantly reducing the amount of feedback information required.
Solution Approach 2:
The channel state information is segmented into two parts: the complete channel matrix (processed locally at reception) and the quantization vector index (fed back to transmission). This segmentation allows the system to utilize detailed channel information for improving transmission characteristics while minimizing feedback overhead by transmitting only the compressed index.
2Reliability
If the reception side uses ML detection method to further improve transmission characteristics, then transmission characteristics are improved, but the complexity of detection increases
Solution Approach 1:
The patent performs preliminary channel quantization and selects the optimal quantization vector index before the actual detection process. By pre-processing the channel state information and preparing the quantization codebook at the reception side, the system reduces the computational complexity of the ML detection while maintaining its ability to improve transmission characteristics.
3Reliability
If hybrid ARQ scheme is used for retransmission, then reliability is improved, but channel gain changes are insufficient limiting effectiveness
Solution Approach 1:
The patent dynamically adjusts the beamforming matrix at the transmission side based on the quantization vector index fed back from the reception side. This dynamic adaptation allows the system to achieve significant channel gain changes during retransmissions, thereby improving the effectiveness of hybrid ARQ schemes while maintaining high reliability.
Solution Approach 2:
The patent implements a feedback mechanism where the reception side feeds back the quantization vector index to the transmission side. This feedback enables the transmission side to adjust the beamforming parameters and achieve different channel gains for retransmitted streams, enhancing the effectiveness of hybrid ARQ without requiring excessive feedback information.
4Loss of information
If quantization vector index is fed back instead of complete channel matrix, then feedback information amount is reduced, but transmission precision may be compromised
Solution Approach 1:
The patent creates a compressed representation (quantization vector index) that copies the essential characteristics of the complete channel matrix. This index serves as a simplified copy that contains sufficient information for the transmission side to reconstruct an accurate beamforming matrix, thereby reducing feedback information while maintaining transmission precision.
Data Source
AI summary
A receiving apparatus includes a combining and quantizing unit that combines channel vectors corresponding to a combination of a plurality of antennas in order to generate a combination channel vector and selects a predetermined quantization vector according to the generated combination channel vector, an error detecting unit that detects whether there is an error in received signals, and an antenna switchover unit that switches over the combination of the antennas according to a result of the error detection, in which the combining and quantizing unit feeds an index of the selected predetermined quantization vector back to a transmitting apparatus. In this way, diversity effect can be obtained by means of repeat control while reducing the amount of feedback information.