Orthogonal Beamforming Weight Generation for MIMO Systems
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Solution Overview
Problem
Current MIMO beamforming weight computation algorithms require complex calculations such as matrix inversions or eigenvalue decompositions, which are computationally intensive and burdensome for wireless communication systems, especially in downlink MIMO transmission where accurate channel coefficients are lacking.
Innovation Solution
A method to compute orthogonal or partially orthogonal beamforming weight vectors using uplink channel information with reduced processing resources, involving a combination of prediction processes and orthogonal computation, applicable to frequency division duplex (FDD) or time division duplex (TDD) MIMO systems, specifically for macrocell/microcell environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex beamforming weight computation algorithms (matrix inversions or eigenvalue decompositions) are used, then accurate downlink beamforming weights can be obtained, but the processing capability and computation resources are significantly burdened
Solution Approach 1:
The patent segments the beamforming weight computation into two parts: (1) generating multiple candidate beamforming weights using simplified methods, and (2) selecting the optimal candidate based on channel covariance matching. This avoids the need for complex matrix inversions or eigenvalue decompositions while maintaining acceptable accuracy through selective candidate evaluation.
Solution Approach 2:
The patent uses multiple candidate beamforming weights that are computationally inexpensive to generate, replacing the need for expensive complex computations. These candidates are generated using simpler algorithms and then evaluated against channel covariance to select the best match, trading off some computational expense for reduced complexity.
2Measurement precision
If downlink channel covariance is used to determine downlink beamforming weights, then accurate beamforming can be achieved, but this information is unavailable in FDD systems or one-sounding TDD MIMO systems
Solution Approach 1:
The patent uses uplink channel covariance as an intermediary to infer downlink channel characteristics. By computing downlink channel covariance from available uplink channel information, the system bridges the information gap in FDD systems where direct downlink channel measurement is not available, enabling beamforming weight optimization without requiring unavailable downlink channel knowledge.
Solution Approach 2:
The patent inverts the traditional approach by using uplink channel information to determine downlink beamforming weights, rather than requiring direct downlink channel measurements. This reverse approach leverages the reciprocity of wireless channels to obtain the necessary information from the opposite direction where it is available.
3Device complexity
If uplink channel covariance is used to compute downlink beamforming weights, then computation resources are reduced, but this approach is not applicable in many situations
Solution Approach 1:
The patent creates a universal beamforming weight computation method that works across different system configurations (FDD and TDD). By using uplink channel covariance to generate candidate weights and then selecting based on downlink channel covariance matching, the approach adapts to various scenarios where direct downlink channel information is unavailable or limited, enhancing system versatility.
Data Source
AI summary
Techniques are provided for computing beamforming weight vectors useful for multiple-input multiple-output (MIMO) wireless transmission of multiple signals streams from a first device to a second device. The techniques involve computing a plurality of candidate beamforming weight vectors based on the one or more signals received at the plurality of antennas of the first device. A sequence of orthogonal/partially orthogonal beamforming weight vectors are computed from the plurality of candidate beamforming weight vectors. The sequence of orthogonal/partially orthogonal beamforming weight vectors are applied to multiple signal streams for simultaneous transmission to the second device via the plurality of antennas of the first device.