Radio Transmitter Dithering for Unwanted Emission Control
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Solution Overview
Problem
Radio communications devices with active antenna systems face challenges in managing unwanted emissions, which can lead to disruptive interference and require significant power reduction or complex linearization schemes to meet emissions limits, complicating beamforming and increasing costs and complexity.
Innovation Solution
The method involves adjusting signal parameters, such as power amplifier bias, digital pre-distortion, and filtering, across multiple radio transmitter units to de-correlate unwanted emissions, allowing for efficient handling of unwanted emissions without reducing the power or directivity of the wanted signal, and avoiding the need for complex linearization schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the power of transmitters is reduced to compensate for antenna gain in unwanted emissions, then unwanted emissions limits are met, but the power and directivity of the wanted signal are reduced
Solution Approach 1:
The patent applies parameter changes by dithering radio parameter values (such as phase, frequency, or amplitude parameters) across multiple transmitter units. This creates intentional variations in the transmission parameters that de-correlate unwanted emissions between transmitters, reducing the antenna gain effect on emissions while preserving the desired beamforming gain for the wanted signal.
Solution Approach 2:
The patent implements dynamics by making the radio parameter values time-varying through dithering. The parameters are dynamically adjusted across transmitter units, creating a time-varying pattern that prevents coherent addition of unwanted emissions while maintaining the spatial coherence needed for beamforming of the intended signal.
2Object-generated harmful factors
If sophisticated linearization schemes are used to reduce unwanted emissions, then emissions limits are met, but device complexity and cost increase
Solution Approach 1:
Instead of using complex linearization schemes, the patent employs parameter changes through dithering of radio parameter values. This simpler approach achieves emission reduction by creating parameter variations that de-correlate emissions, avoiding the need for sophisticated linearization hardware and algorithms.
Solution Approach 2:
The patent extracts the emission control function from complex linearization schemes and implements it through simple parameter dithering. By separating the emission reduction mechanism from the signal processing chain, the system achieves emission limits without requiring complex linearization infrastructure.
3Object-generated harmful factors
If dithering of radio parameter values is applied to de-correlate unwanted emissions, then Equivalent Isotropic Radiated Power of emissions is reduced, but signal processing complexity increases
Solution Approach 1:
The patent implements parameter changes by dithering radio parameter values across transmitter units. This creates controlled variations in transmission parameters that reduce the coherent addition of unwanted emissions, achieving lower EIRP for emissions while maintaining beamforming performance for the wanted signal.
Solution Approach 2:
The dithering process employs periodic action by systematically varying radio parameter values in a periodic or pseudo-periodic manner across transmitter units. This periodic variation ensures consistent de-correlation of unwanted emissions while maintaining the overall signal structure and beamforming characteristics.
Data Source
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AI summary
There is provided mechanisms for transmitting adjusted signals. A method is performed by a radio communications device comprising at least two radio transmitter units. The method comprises generating a signal to be transmitted by the radio transmitter units. The method comprises adjusting the signal at at least one of the radio transmitter units by dithering at least one radio parameter value such that the signals from all radio transmitter units are mutually different. The method comprises transmitting the adjusted signal by the radio transmitter units