Phased Array Beam Squinting for Spatial-Spectral Multiplexing
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Solution Overview
Problem
Phased array antennas in 6G mobile communication systems suffer from beam squinting, leading to energy loss and limited geographical coverage due to frequency-dependent defocusing of antenna beams, exacerbated by reconfigurable intelligent surfaces (RIS), which existing technologies have not adequately addressed.
Innovation Solution
A wireless communication system utilizing beam squinting to split a broadband signal into frequency ranges using a phased array antenna and RIS, steering subcarrier signals into divergent directions for spatial and spectral multiplexing, enabling efficient data transmission to multiple user equipment devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If phased array antennas apply beamforming with phase shifted signals to direct transmission signals, then geographical coverage is improved, but beam squinting causes frequency-dependent defocusing and energy loss
Solution Approach 1:
The broadband signal is segmented into multiple frequency sub-bands, each handled by different antenna elements or beamforming weights. This allows each frequency component to be optimized independently, reducing the beam squinting effect while maintaining wide geographical coverage.
Solution Approach 2:
The beamforming weights and phase shifts are made dynamic and frequency-dependent rather than static. By adapting the beamforming parameters across different frequencies, the system compensates for beam squinting and maintains focus across the broadband spectrum, reducing energy loss.
2Area of stationary object
If phased array antennas increase deflection angle to expand coverage area, then geographical coverage is improved, but beam squinting is aggravated causing more severe defocusing
Solution Approach 1:
Different regions of the antenna array are assigned different beamforming characteristics optimized for specific frequency ranges and deflection angles. This local optimization allows large deflection angles to be achieved while maintaining beam focusing precision through frequency-specific weight adjustments.
Solution Approach 2:
The beamforming parameters (phase shifts, amplitude weights) are changed as a function of frequency to compensate for beam squinting. By dynamically adjusting these parameters across the frequency spectrum, the system maintains beam focusing precision even at large deflection angles.
3Area of stationary object
If reconfigurable intelligent surfaces reflect transmission signals to overcome obstacles, then line of sight coverage is improved, but beam squinting at RIS surface causes additional energy loss
Solution Approach 1:
The RIS acts as an intermediary that actively compensates for beam squinting by applying frequency-dependent phase shifts to reflected signals. This intermediary function corrects the frequency-dependent defocusing caused by both the transmitting antenna and the RIS surface, reducing energy loss.
Solution Approach 2:
The system employs feedback mechanisms where the RIS controller receives information about the incident signal characteristics and adjusts reflection phases accordingly. This feedback enables real-time compensation for beam squinting effects, minimizing energy loss at the reflection point.
4Productivity
If wideband signals are transmitted to increase data capacity, then transmission capacity is improved, but beam squinting causes spectral components to deflect differently reducing reception quality
Solution Approach 1:
The wideband signal is divided into multiple frequency sub-bands or sub-carriers, each experiencing different beam squinting effects. By segmenting the spectrum and applying frequency-specific beamforming, the system maintains reception quality across the entire bandwidth while preserving high data transmission capacity.
Solution Approach 2:
The beamforming system dynamically adapts its parameters across the frequency spectrum to compensate for differential deflection of spectral components. This dynamic frequency-dependent beamforming ensures that all spectral components are properly focused at the receiver, maintaining reception quality for wideband transmissions.
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
Enhances data transmission capacity by mitigating the negative effects of beam squinting, allowing simultaneous service to multiple devices with high data rates and stable reception, particularly suitable for OFDM and OFDM-A modulation.
Implementation Method 1
the phased array antennas apply phase shifted signals to individual antenna elements of the phased array antenna
Implementation Method 2
the antennas will apply beamforming with phased array antennas to direct their transmission signal to a reception point
Implementation Method 3
The sub-carriers of the transmission signal are received at different adjustable reflective areas. The reflective areas of the reflection device (RIS) steer the subcarrier signals of the transmission signal into divergent directions
Implementation Method 4
Phased array antennas suffer from beam squinting, i.e. the emission angle of the transmission signal is frequency dependent because the phased array antennas apply phase shifted signals to individual antenna elements
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A wireless communication system (100) and a method for operating the system is suggested. The wireless communication system comprises a transmitter (112) for generating a high frequency transmit signal having a defined carrier frequency and bandwidth. The transmit signal is modulated according to a modulation method using multiple sub-carriers with different subcarrier frequencies. The transmission signal is emitted by a phase array antenna (113) at a selectable emission angle (steering vector). The actual emission angle is frequency dependent, such that transmit signal spectral components at a lower edge of the bandwidth are deflected differently than transmitter signal portions at a higher edge of the bandwidth. The system further comprises a reflection device (119) with multiple adjustable reflective areas (121a-d). The sub-carriers of the transmission signal are received at different adjustable reflective areas and reflected by the reflective areas into divergent directions enabling reception at different reception points.