MIMO Antenna Array Layout for Out-of-Band Emission Suppression
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Solution Overview
Problem
Current wireless communication systems face challenges in managing out-of-band emissions without affecting in-band signals, leading to inefficient power usage and increased interference.
Innovation Solution
An antenna array configuration with alternating digital pre-distortion-less linear and non-linear elements, where every second element in a direction is non-linear, and spacing between elements is less than half a free space wavelength, applies non-linear precoding to convert out-of-band emissions into reactive power in the near-field, ensuring in-band signals remain unaffected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If non-linear elements are used in the antenna array, then out-of-band emissions are converted into reactive power, but in-band signals may be affected
Solution Approach 1:
The antenna array is segmented into alternating linear and non-linear elements. The linear elements (every second element) are responsible for maintaining in-band signal quality, while the non-linear elements convert out-of-band emissions into reactive power. This segmentation allows each type of element to specialize in its function without interfering with the other's performance.
Solution Approach 2:
Different elements in the antenna array are assigned different local qualities - linear elements maintain constant impedance characteristics for in-band signals, while non-linear elements are designed to convert out-of-band emissions. This local differentiation allows the system to simultaneously achieve both goals of reducing out-of-band emissions and preserving in-band signal quality.
2Device complexity
If element spacing is reduced to less than half wavelength, then mutual coupling effects increase, but array factor control improves
Solution Approach 1:
The element spacing parameter is changed to be less than half the wavelength (specifically between 0.2λ to 0.4λ). This parameter change enables better control of the array factor and directional radiation patterns while the alternating linear and non-linear element configuration compensates for mutual coupling effects through their complementary impedance characteristics.
3Object-generated harmful factors
If alternating linear and non-linear elements are used, then out-of-band emissions are reduced, but device complexity increases
Solution Approach 1:
The antenna array employs an asymmetric configuration where every second element alternates between linear and non-linear types. This asymmetric arrangement creates complementary impedance patterns that naturally cancel out out-of-band emissions while maintaining a relatively simple overall structure that can be implemented using standard antenna element designs.
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 effectively reduces out-of-band emissions while maintaining in-band signal quality, enhancing power efficiency and minimizing interference, by converting out-of-band emissions into reactive power without dissipating them.
Implementation Method 1
the nonlinear precoding converting out-of-band emissions of the transmissions into reactive power in the near-field around the antenna array
Data Source
AI summary
Antenna arrays to be used in MIMO apparatuses are disclosed. Such an antenna array may include a plurality of array elements, wherein every second element in a first direction is a digital pre-distortion-less linear element, and every second element in the first direction is a non-linear element. In the antenna array, spacing between adjacent elements in the first direction is less than a half of a free space wavelength. A non-linear precoding is applied to transmissions from the antenna array, the non-linear precoding converting out-of-band emissions of the transmissions into reactive power in the near-field around the antenna array while ensuring that in-band signals generated by the elements remain unaffected.