MIMO Beamforming Orthogonal Vector Selection
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Solution Overview
Problem
Conventional MIMO systems face high computational complexity and unequal power distribution among antennas due to the use of singular value decomposition (SVD) for beam-forming, leading to increased costs and requirements for power amplifier linearity.
Innovation Solution
A beam-forming method in MIMO systems that generates channel estimations, determines and selects candidate transmitting vectors based on these estimations to ensure orthogonality and equal power distribution, and adjusts vector magnitudes to optimize signal transmission across multiple antennas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SVD method is used to determine transmitting vectors, then data streams can be separated after wireless transmission, but computational complexity increases significantly
Solution Approach 1:
The patent segments the beam-forming process into discrete steps: generating candidate transmitting vectors based on channel estimations, selecting vectors that satisfy orthogonality conditions, and adjusting power distribution. This segmentation avoids the need for complete SVD decomposition while achieving the same functional goals of data stream separation.
Solution Approach 2:
The patent uses simplified candidate transmitting vectors that are easier to compute than full SVD vectors. These candidate vectors are generated through less computationally intensive methods and discarded after selection, replacing the need for expensive SVD calculations while maintaining the ability to separate data streams.
2Reliability
If SVD method is used to determine transmitting vectors, then data stream orthogonality is achieved, but unequal power distribution among antennas occurs
Solution Approach 1:
The patent changes the parameters of the transmitting vectors by explicitly controlling power distribution as a separate constraint. After selecting candidate vectors that satisfy orthogonality, the patent adjusts their magnitudes to ensure equal power distribution among antennas, thereby decoupling the orthogonality requirement from the power distribution issue.
Solution Approach 2:
The patent applies different properties to different aspects of the transmitting vectors: orthogonality is ensured through the selection criterion, while equal power distribution is achieved through separate magnitude adjustment. This local optimization of different vector properties resolves the contradiction between maintaining orthogonality and achieving equal power distribution.
3Device complexity
If unequal power distribution among antennas is accepted, then computational complexity is reduced, but PA linearity requirements and cost increase
Solution Approach 1:
The patent performs preliminary power distribution adjustment during the transmitting vector selection phase, before the signals are amplified by the power amplifiers. By pre-balancing the power distribution among antennas in the vector design, the patent eliminates the need for high PA linearity, thereby reducing manufacturing costs while maintaining simple computational procedures.
Data Source
AI summary
A beam-forming apparatus applied in a Multiple Input Multiple Output (MIMO) system and a related method where the MIMO system transmits signals through a plurality of channels. The method includes generating a plurality of channel estimations corresponding to the channels; determining a plurality of first candidate transmitting vectors; selecting a first transmitting vector from the first candidate transmitting vectors according to the channel estimations; determining a plurality of second candidate transmitting vectors orthogonal to the first transmitting vector; selecting a second transmitting vector from the second candidate transmitting vectors according to the channel estimations; generating a plurality of transmitted signals by combining a first data stream and a second data stream according to the first and second transmitting vectors; and respectively transmitting the transmitted signals through a plurality of antennas. The apparatus ensures that power of a data stream is distributed equally for each antenna.