Smart Antenna Beamforming with Quantised Weight Set Selection
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Solution Overview
Problem
Modern smart antenna systems suffer from high side lobe levels due to coarse quantisation of antenna element weights, which degrade signal-to-noise ratio by receiving unwanted signals.
Innovation Solution
A smart antenna system that generates multiple quantised weight sets with different side lobe levels by applying a constant phase rotation to the initial weight set, selecting the set with the lowest side lobe level using an array factor calculation, implemented efficiently with RTL-based digital modules like FPGA or ASIC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If coarse quantisation of antenna element weights is used, then device complexity is reduced, but side lobe levels increase
Solution Approach 1:
The system pre-calculates multiple quantised weight sets with different phase rotations before operation. These weight sets are prepared in advance and stored for selection during operation, allowing the system to quickly switch to an optimal weight set without real-time complex calculations.
Solution Approach 2:
The system varies the phase rotation parameter across different quantised weight sets. By applying different constant phase rotations to the initial weight set, multiple quantised versions are generated, each with potentially different side lobe characteristics. The system selects the weight set that provides the lowest side lobe level while maintaining the desired beam direction.
2Object-generated harmful factors
If multiple quantised weight sets are generated and evaluated, then side lobe levels are reduced, but computational complexity increases
Solution Approach 1:
Multiple quantised weight sets and their corresponding array factors are calculated in advance during a setup phase. This preliminary calculation eliminates the need for complex real-time computations during operation, as the system only needs to select from pre-evaluated weight sets based on measured signal conditions.
Solution Approach 2:
The system generates more quantised weight sets than strictly necessary (excessive action) to ensure that at least one set provides sufficiently low side lobe levels. Rather than finding the single optimal weight set, the system generates multiple candidates and selects from those that meet performance thresholds, reducing computational burden.
3Object-generated harmful factors
If array factor calculation is used to evaluate weight sets, then side lobe level optimization is achieved, but processing time increases
Solution Approach 1:
The array factor calculations for all candidate quantised weight sets are performed in advance during system initialization or reconfiguration phases. This allows the system to store pre-computed side lobe level information for each weight set, enabling rapid selection during operation without performing time-consuming calculations in real-time.
Data Source
AI summary
A smart antenna system is configured to generate an initial weight set from an indication of desired azimuth and elevation steering angle and from an indication of frequency, to generate a plurality of further weight sets from the initial weight set, the further weight sets each being for the same azimuth and elevation steering angle, and for the initial weight set and for each of the plurality of further weight sets, generating a respective quantised wight set and generating an indication of side lobe level for each respective quantised weight set. A weight set is selected from the generated quantised weight sets for application to an antenna array on the basis of the indications of side lobe level.