Wireless Apparatus Beamforming Image Component Cancellation
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Solution Overview
Problem
The use of frequency scanning mode beamforming in wireless communication apparatuses leads to increased circuit complexity due to the generation of image components, requiring band-pass filters to remove these components, which complicates the design and increases costs.
Innovation Solution
A wireless communication apparatus that employs a processor to generate in-phase and quadrature signals, which are then modulated using quadrature modulators with frequency shifts applied to cancel out image components, eliminating the need for band-pass filters by performing complex multiplication and IQ modulation to maintain constant signal frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If frequency scanning mode beamforming is used with mixers provided to respective antenna elements, then beam direction control is achieved, but image components are generated requiring band-pass filters
Solution Approach 1:
The patent extracts and removes the image components generated by the mixers through the use of band-pass filters. By identifying the specific frequency characteristics of image components and designing BPFs to target these frequencies, the harmful image components are separated and removed from the desired signal path, resolving the contradiction between achieving beam control and managing circuit complexity.
Solution Approach 2:
The band-pass filter acts as an intermediary element between the mixer output and the antenna elements. It mediates the signal by allowing only the desired frequency components to pass through while blocking the image components, thus enabling beam direction control without the harmful effects of image components reaching the antenna.
2Reliability
If band-pass filters are added to remove image components, then signal purity is improved, but circuit scale increases
Solution Approach 1:
The patent applies local quality by designing band-pass filters with specific frequency characteristics tailored to each mixer's output. Each BPF is configured with center frequency and bandwidth parameters optimized for its specific location in the signal path, allowing effective image component rejection while minimizing the filter's impact on overall circuit scale and maintaining signal integrity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the circuit complexity and cost by eliminating the need for band-pass filters, ensuring constant signal frequencies regardless of beam direction, thereby improving the efficiency and scalability of wireless communication systems.
Implementation Method 1
quadrature modulators that are provided to the respective antenna elements, and that generate transmission signals of a radio frequency to be transmitted from the respective antenna elements by performing quadrature modulation
Implementation Method 2
applying a first frequency shift according to a transmission beam direction to a first oscillation signal that is supplied to the quadrature modulators and used for frequency conversion into the radio frequency
Data Source
AI summary
A wireless communication apparatus includes: a plurality of antenna elements; a processor that outputs an in-phase signal and a quadrature signal; a splitter that distributes the in-phase signal and the quadrature signal to the antenna elements; and a plurality of quadrature modulators that generate transmission signals of a radio frequency by performing quadrature modulation on the in-phase signals and the quadrature signals. The processor is configured to execute a process including applying a first frequency shift according to a transmission beam direction to a first oscillation signal that is supplied to the quadrature modulators, digitally modulating transmission data to generate the in-phase signal and the quadrature signal, and performing complex multiplication to the in-phase signal and the quadrature signal with a second oscillation signal to which a second frequency shift opposite from the first frequency shift is applied.