MIMO Beamforming Steering Vectors Partial Channel Knowledge
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In MIMO systems, beamforming with partial channel knowledge is necessary when the number of transmit chains differs from the number of receive chains, as in conventional WiMAX or WiFi systems, where only a subset of the forward channel matrix is known, requiring effective methods to steer multiple streams without full channel information.
Innovation Solution
A method for selecting steering vectors using a partial channel matrix to steer streams between transmit and receive antennas, where independent vectors are used for the known channels and orthogonal vectors are used for the null space to transmit additional streams, ensuring efficient beamforming even with limited channel knowledge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If beamforming is performed with full channel knowledge using all receive antennas, then beamforming performance is optimized, but system complexity increases and not all receive antennas may be available
Solution Approach 1:
The patent segments the channel knowledge into two parts: full channel knowledge for a subset of receive antennas and partial channel knowledge for remaining antennas. This allows the system to perform beamforming optimization on the subset with full knowledge while handling other antennas with reduced complexity methods.
Solution Approach 2:
The patent applies partial action by obtaining full channel knowledge for only a subset of receive antennas rather than all antennas. This partial approach achieves good beamforming performance for the known subset while reducing overall system complexity and resource requirements.
2Loss of information
If the number of transmit chains equals the number of receive chains, then full channel matrix is known, but this configuration is not practical in conventional systems
Solution Approach 1:
The patent segments the channel knowledge acquisition process by dividing receive antennas into two groups: those with full channel knowledge and those with partial channel knowledge. This segmentation allows the system to operate with asymmetric transmit-receive chain configurations while still achieving effective beamforming.
Solution Approach 2:
The patent changes the parameter of channel knowledge completeness from binary (full or none) to a spectrum where different receive antennas can have different levels of channel knowledge. This allows flexible adaptation to various system configurations including conventional WiMAX and WiFi systems with unequal transmit-receive chain counts.
3Productivity
If independent vectors are used for known channels and orthogonal vectors for null space, then multiple streams can be transmitted effectively, but vector selection complexity increases
Solution Approach 1:
The patent segments the steering vectors into two categories: independent vectors for streams corresponding to receive antennas with full channel knowledge, and orthogonal vectors for streams corresponding to the null space. This segmentation enables efficient multi-stream transmission by optimizing each category separately according to its channel knowledge level.
Solution Approach 2:
The patent applies partial action by using independent vectors only for the subset of streams where full channel knowledge exists, rather than attempting to find optimal independent vectors for all streams. The remaining streams use simpler orthogonal vectors, reducing overall computational complexity while maintaining good throughput.
Data Source
AI summary
An apparatus for use in transmit beamforming to a beamformee having NR receive antennas. The apparatus includes a controller configured to i) construct a partial channel matrix that describes a multiple input, multiple output (MIMO) channel between a beamformer and M receive antennas, wherein M is less than NR, and ii) generate L independent vectors using the partial channel matrix, wherein L is a rank of the partial channel matrix. When a number NS of one or more streams is greater than L, the controller is further configured to i) select the L independent vectors as steering vectors to steer L streams of the plurality of streams, and ii) select NS−L orthogonal vectors in a null space of the L independent vectors as steering vectors to steer a remainder of the streams in the plurality of streams.