Beamforming Signal Generation With Sideband Switching for Multi-Band MIMO
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Solution Overview
Problem
Current MIMO-based communication systems face challenges in achieving high effective output and input power while minimizing power consumption and area, particularly in compact, cost-effective designs for next-generation communication systems like 5G services, where complex RF circuits and large arrays of antennas are costly and inefficient.
Innovation Solution
The implementation of a low power transmit and/or receive antenna array system using trigonometric weighted vector modulation techniques, including baseband scalar weighting and quadrature-phased signals at LO and RF frequencies, with moderate tuning range VCOs and reconfigurable frequency dividers, to enhance effective power and reduce distortion and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If complex RF circuits are used in each transmitter element to achieve high effective output power, then the transmitted power is improved, but the system cost and circuit complexity increase substantially
Solution Approach 1:
The system divides the complex RF signal generation into separate functional blocks: baseband processing stage, intermediate frequency processing stage, and RF transmission stage. Each transmitter element is segmented into independent functional modules (phase shifters, modulators, power amplifiers) that can be optimized separately, reducing overall system complexity while maintaining high effective output power through coordinated operation of these segmented components
Solution Approach 2:
An intermediate frequency (IF) stage is introduced as a mediator between baseband and RF stages. The IF processing stage handles complex signal manipulation at a lower frequency where circuit implementation is simpler, then passes the processed signal to the RF stage for final transmission. This intermediary approach allows complex signal processing to be performed with less complex circuits compared to direct RF modulation
2Productivity
If multiple transmitter elements are used to achieve high data throughput through MIMO, then the data throughput is improved, but the system area and cost increase
Solution Approach 1:
The transmitter array is designed with universal, identical transmitter element modules that can perform multiple functions: each element can transmit independently for spatial diversity, combine with other elements for beamforming, or operate in different MIMO modes (spatial multiplexing, transmit diversity). This multi-functionality allows high data throughput through MIMO operations while using compact, standardized elements that minimize total system area compared to custom-designed large-scale arrays
Solution Approach 2:
The transmitter elements are designed with nested functional structures where common components (local oscillators, reference signal generators, control logic) are shared across multiple elements through hierarchical architecture. Lower-level functions are nested within element modules, while higher-level functions are implemented in centralized units, allowing dense packing of multiple elements in reduced area while maintaining full MIMO functionality
3Power
If phase shifting of adjacent transmitter elements is used to generate higher effective output power, then the transmitted power is improved, but the device complexity increases
Solution Approach 1:
Traditional mechanical or analog phase shifting mechanisms are replaced with digital phase control implemented through software-defined radio (SDR) architecture. Phase shifts are applied digitally in the baseband or intermediate frequency domain using programmable logic and digital signal processing, eliminating complex mechanical phase shifters and reducing device complexity while maintaining the ability to generate higher effective output power through constructive interference of phase-shifted signals
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 enables efficient, scalable, and cost-effective MIMO systems with improved signal-to-noise ratios and reduced power consumption, suitable for multi-band operations across various frequency bands, such as 28 GHz and 35 GHz, by using trigonometric weighted vector modulation and phase-based waveform reconstruction.
Implementation Method 1
The phase shifting of adjacent transmitter elements generates a higher effective output power based on constructive addition of electromagnetic waves in space
Implementation Method 2
The local oscillator (LO) frequencies are generated coherently using reconfigurable frequency divider and multipliers
Data Source
AI summary
Transmit and/or receive beamforming signal generation includes a voltage-controlled oscillator (VCO) for generating a lower or higher master frequency output signal in accordance with a selection of a lower or higher frequency carrier frequency. A local oscillator generates local oscillator signals in quadrature in response to the maser frequency output signal. One or more mixer stages generate sidebands in response to a received information signal and the local oscillator signals in quadrature. The one or more mixer stages generate an output information signal in response to high-side injection of lower sidebands of the developed sidebands when the lower frequency carrier frequency is selected, and generate the output information signal in response to low-side injection of higher sidebands of the developed sidebands when the higher frequency carrier frequency is selected. Multi-band operation of transmit and receive arrays can be performed.