RF Front-End Phase Synchronization for TDD Beamforming Arrays
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Solution Overview
Problem
Beamforming transmitters in wireless networks face challenges in maintaining accurate phase control due to unpredictable static phase differences between antenna elements, particularly in time-division duplex (TDD) systems, where the initial phase of each antenna element is unknown upon startup, affecting the radiation pattern and overall performance.
Innovation Solution
The solution involves determining the initial phase of each output signal generated by RF front-end circuits by measuring the time difference between a reference signal and a mixing signal, allowing for accurate phase control of the corresponding antenna element, using a method that includes generating a reference signal common to all RF front-end circuits and measuring the time difference between the start and stop edges of the mixing signal to determine the initial phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If local oscillator beamforming is implemented with phase shifting for each antenna element, then directional signal control is achieved, but static phase differences between transmitters become unpredictable and difficult to control
Solution Approach 1:
The patent applies preliminary action by measuring and storing the initial phase of each RF front-end circuit before normal beamforming operation begins. This pre-measurement captures the static phase characteristics that would otherwise be unpredictable, allowing the system to compensate for these phase differences during subsequent beamforming operations rather than attempting to control them in real-time.
Solution Approach 2:
The patent implements feedback by using the measured initial phase information to adjust and compensate for phase differences in the beamforming process. The system feeds back the measured phase characteristics into the phase control mechanism, enabling accurate phase alignment despite variations in circuit startup states and component tolerances.
2Use of energy by moving object
If each antenna element has its own transmitter powered down between transmission slots, then power consumption is reduced, but the initial phase becomes unknown each time the transmitter is powered back on
Solution Approach 1:
The patent measures and stores the initial phase of each RF front-end circuit before normal beamforming operation begins. This pre-measurement captures the static phase characteristics that would otherwise be unpredictable, allowing the system to compensate for these phase differences during subsequent beamforming operations rather than attempting to control them in real-time.
Solution Approach 2:
The system performs self-characterization by automatically measuring and storing its own phase properties during a calibration phase. Each RF front-end circuit's initial phase is measured and stored in memory, enabling the system to self-correct for phase variations without requiring external calibration equipment or complex real-time phase control during active transmission slots.
3Measurement precision
If the initial phase of each antenna element is unknown upon startup, then phase control accuracy deteriorates, but adding phase measurement and compensation circuitry increases system complexity
Solution Approach 1:
The patent measures and stores the initial phase of each RF front-end circuit before normal beamforming operation begins. This pre-measurement captures the static phase characteristics that would otherwise be unpredictable, allowing the system to compensate for these phase differences during subsequent beamforming operations rather than attempting to control them in real-time.
Solution Approach 2:
The patent introduces an intermediary calibration phase that bridges the gap between unpredictable circuit startup states and controlled beamforming operation. During this intermediate phase, the system measures and stores phase characteristics, creating a lookup table of phase offsets that mediates between the random initial states and the controlled beamforming requirements, simplifying the overall control architecture.
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 precise phase control of antenna elements, ensuring consistent radiation patterns and improved performance in beamforming transmitters, even in TDD systems, by accounting for start-up phase variations and ensuring accurate phase initialization.
Implementation Method 1
each RF front-end circuit comprises a mixer configured to mix an input signal with a mixing signal to generate the output signal for that RF front-end circuit
Data Source
AI summary
An initial phase of each output signal generated by a plurality of radio frequency (RF) front-end circuits is determined by mixing an input signal with a mixing signal in a mixer of the corresponding RF front-end circuit. To that end, a time difference for each of the plurality of RF front-end circuits is determined by measuring a time difference between a reference signal (common to all of the RF front-end circuits) and the mixing signal of each RF front-end circuit. The initial phase for each output signal is then determined based on the measured time difference for the corresponding RF front-end circuit. Determining the initial phase in this manner accounts for any uncertainty of the phase when the RF front-end circuits are activated, enabling the phase of the corresponding antenna element to be accurately controlled.