MIMO Beamforming Feedback Using Reduced Channel Matrix Dimensions
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Solution Overview
Problem
In wireless communication systems, when the number of antennas at the transmitter (beamformer) is less than that at the receiver (beamformee), existing closed loop type MIMO communication methods face challenges in performing effective beamforming without increasing processing capability or circuit size, leading to reduced communication efficiency and increased overhead.
Innovation Solution
The system notifies the receiver of a maximum dimension for computing the transmission weight matrix, allowing it to suppress the channel matrix dimension to match the transmitter's processing capability, enabling efficient beamforming by transmitting a training sequence corresponding to the transmitter's antennas and estimating the channel matrix with reduced dimensions, thereby reducing circuit size and overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the receiver computes the full M×N channel matrix when M > N, then complete channel information is obtained, but processing capability requirements and circuit size increase
Solution Approach 1:
The invention extracts only the necessary N×N portion from the full M×N channel matrix. The receiver identifies and feeds back only the channel information corresponding to the N transmission antennas, excluding the redundant (M-N) rows. This extraction principle reduces the feedback data size while maintaining the completeness needed for beamforming computation at the transmitter.
Solution Approach 2:
The invention applies partial action by computing and feeding back only the necessary N×N submatrix rather than the complete M×N channel matrix. This partial computation suffices for the beamforming operation since the transmitter only has N antennas, making the full M×N matrix excessive and unnecessary for the actual beamforming computation.
2Reliability
If explicit feedback is used to share channel information, then beamforming performance is improved, but feedback overhead and delay increase
Solution Approach 1:
The invention extracts and feeds back only the essential N×N portion of the channel matrix rather than the complete M×N matrix. This reduction in feedback data size directly decreases the feedback overhead and transmission time, while the extracted information remains sufficient for accurate beamforming computation at the transmitter.
Data Source
AI summary
A wireless communication system is disclosed. The wireless communication system performs data transmission using spatially multiplexed streams from a first terminal including N antennas to a second terminal including M antennas (N and M are integers larger than or equal to 2 and N>M).