MIMO Precoding Matrix Grouping for Inter-User Interference Reduction
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Solution Overview
Problem
Current MIMO communication systems face inefficiencies in channel optimization due to non-orthogonal spatial beams and increased feedback overhead, limiting data throughput and channel performance, especially in multi-user scenarios where inter-user interference is difficult to eliminate.
Innovation Solution
A method that groups receivers based on channel state information feedback to generate orthogonal precoding matrices, reducing inter-user interference and optimizing channel performance by applying these matrices to input signals, and utilizing codebook elements to minimize feedback overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If block diagonalization algorithm is used for precoding in MU-MIMO systems, then inter-user interference can be cancelled, but orthogonality between spatial beams is not guaranteed and the constraint on antenna configuration dimension is not satisfied in practical cases
Solution Approach 1:
The patent divides receivers into multiple groups based on channel state information feedback. Each group is processed independently with dedicated precoding matrices, ensuring orthogonality within each group while managing inter-user interference segment by segment rather than attempting to cancel all interference simultaneously across the entire system.
Solution Approach 2:
The patent changes the parameter of precoding matrix construction by using QR decomposition instead of traditional block diagonalization. This parameter change allows the system to satisfy antenna configuration constraints while maintaining orthogonality and reducing inter-user interference through a different mathematical approach that doesn't require the restrictive dimension constraints of block diagonalization.
2Reliability
If channel state information is directly fed back from receivers to transmitter for calculating precoding matrix, then channel optimization can be achieved, but increased feedback overhead results in bandwidth non-efficiency
Solution Approach 1:
The patent extracts only the essential channel state information parameters needed for precoding optimization and feeds back only these extracted parameters rather than complete channel matrices. This extraction approach maintains channel optimization capability while significantly reducing feedback overhead and improving bandwidth efficiency.
Solution Approach 2:
The patent uses partial channel state information feedback rather than complete channel information. By providing just sufficient information for effective precoding without excessive detail, the system achieves good channel optimization while avoiding the bandwidth waste associated with complete channel state feedback.
3Loss of energy
If codebook-based precoding methods are used, then feedback overhead can be reduced, but these methods are typically only used for single user MIMO systems since there is no other users' channel information available in each receiver in MU-MIMO systems
Solution Approach 1:
The patent develops a codebook-based precoding method that serves multiple functions: it reduces feedback overhead like in SU-MIMO systems while also enabling multi-user support through the addition of receiver grouping and orthogonality enforcement mechanisms. This makes the codebook approach universally applicable to both SU-MIMO and MU-MIMO scenarios.
Solution Approach 2:
The patent introduces receiver grouping as an intermediary mechanism that enables codebook-based precoding to work in MU-MIMO systems. By grouping receivers with orthogonal channel characteristics together, the system can use codebook indices for feedback while the grouping structure provides the necessary multi-user coordination that codebook methods alone cannot achieve.
Data Source
AI summary
A transmission method in a multiple-input multiple-output (MIMO) communication system, a transmitter in a MIMO communication system and a MIMO communication system are provided. The method comprises the steps of: receiving feedback data representing channel state information from respective receivers of the MIMO communication system; grouping the receivers into one or more groups based on the received feedback data; obtaining a precoding matrix for each group of receivers based on the received feedback data such that precoding vectors or sub-matrices in the precoding matrix associated with respective receivers of said each group of receivers are orthogonal to each other; and applying the precoding matrix to input signals for transmission to said each group of receivers.