Phase-Shift Precoding for MIMO Feedback Reduction
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Solution Overview
Problem
Conventional phase-shift diversity and precoding schemes in MIMO systems face limitations in achieving high transfer rates and frequency-selective diversity gains, especially in mobile environments with rapidly changing channels, and require significant feedback information.
Innovation Solution
A phase-shift-based precoding method that determines a precoding matrix by multiplying a unitary matrix, a first diagonal matrix, and a phase-shift matrix, and applies this to each sub-carrier or virtual resource, allowing for cyclic repetition of matrices in a codebook based on an index, to enhance communication efficiency and adapt to changing channel conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional phase-shift diversity or precoding schemes are used in MIMO systems, then spatial diversity gain or SNR improvement is achieved, but feedback information requirements increase and adaptability to rapidly changing mobile channel conditions deteriorates
Solution Approach 1:
The patent changes the parameter of phase shift values applied to different antennas, using specific phase relationships (e.g., 0, π/2, π, 3π/2) to create frequency-selective diversity without requiring feedback. This parameter modification enables the system to achieve diversity gain while reducing feedback requirements compared to conventional precoding schemes.
Solution Approach 2:
The patent segments the frequency spectrum into different sub-carriers and applies different phase shift patterns to each antenna across these sub-carriers. This segmentation in the frequency domain enables frequency-selective diversity gain while the segmented phase shift patterns can be predetermined, reducing feedback information requirements.
2Reliability
If conventional precoding schemes are used to increase SNR, then transmission reliability is improved, but device complexity and feedback requirements increase
Solution Approach 1:
The patent implements a self-service mechanism where the phase shift patterns are predetermined and applied automatically at the transmitter without requiring complex feedback processing or adaptive precoding matrix selection. This reduces transceiver complexity while maintaining transmission reliability through frequency-selective diversity.
3Reliability
If conventional phase-shift diversity is used to achieve frequency diversity gain, then communication reliability is improved, but transfer rate and adaptability to mobile environments deteriorate
Solution Approach 1:
The patent introduces dynamic phase shift patterns that can be applied across different sub-carriers and time slots, enabling the system to adapt to changing channel conditions in mobile environments. This dynamic approach maintains communication reliability while improving transfer rates compared to static phase-shift diversity schemes.
Solution Approach 2:
The patent employs periodic phase shift patterns across sub-carriers and time, creating frequency-selective diversity that enhances both reliability and transfer rate. The periodic structure allows for efficient implementation while maintaining adaptability to mobile channel conditions.
Data Source
AI summary
A method for performing a precoding based on a generalized phase shift or a precoding based on an extended phase shift in a Multi-Input Multi-Output (MIMO) system employing several sub-carriers, and a transceiver for supporting the same are disclosed. A phase-shift-based precoding matrix is generalized by multiplying a diagonal matrix for a phase shift by a unitary matrix for maintaining orthogonality between sub-carriers. In this case, a diagonal matrix part may be extended by multiplying a precoding matrix for removing an interference between sub-carriers by a diagonal matrix for a phase shift. By generalization and extension of the phase-shift-based precoding, a transceiver is more simplified, and a communication efficiency increases.