MIMO WiFi Transceiver Rolling Gain Offset Pre-Distortion Calibration
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Solution Overview
Problem
MIMO wireless transceivers face degradation in transmission quality and throughput due to non-linearity introduced by power amplifiers in their transmit chains, which existing technologies have not effectively addressed.
Innovation Solution
A method and apparatus for efficiently calibrating predistortion parameters for each transmit power amplifier in MIMO wireless transceivers, using a pre-distortion calibration circuit with a chain isolator and inverter circuit to determine and compensate for non-linearity, thereby improving the linearity of the amplification process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If power amplifiers are used in MIMO transmit chains to increase transmission power, then transmission coverage and reach are improved, but non-linearity is introduced that degrades transmission quality and throughput
Solution Approach 1:
The patent applies pre-distortion calibration before actual transmission to compensate for PA non-linearity. The calibration circuit determines pre-distortion parameters that are applied to the transmit chains prior to power amplification, preventing non-linearity from degrading transmission quality while maintaining high transmission power.
Solution Approach 2:
The patent implements a feedback mechanism where the calibration circuit monitors the combined output signal from the signal combiner and uses this information to determine and adjust pre-distortion parameters. This closed-loop feedback enables continuous optimization of linearity compensation, maintaining transmission quality despite power amplifier non-linearity.
2Reliability
If traditional calibration methods are used to compensate for PA non-linearity, then transmission quality may be improved, but communication packets must be interrupted causing loss of time and reduced productivity
Solution Approach 1:
The patent enables continuous calibration during ongoing MIMO communications by using the signal combiner to provide a combined output signal that includes contributions from all transmit chains. The calibration circuit processes this combined signal without requiring interruption of communication packets, maintaining continuous useful action and eliminating time loss associated with traditional calibration methods.
Solution Approach 2:
The calibration circuit performs self-calibration by extracting individual chain information from the combined output signal and automatically determining pre-distortion parameters without external intervention or communication interruption. The system serves itself by utilizing the existing combined signal to maintain and optimize transmission quality continuously.
3Productivity
If pre-distortion calibration is performed during ongoing MIMO communications using the combined output signal, then productivity is improved by avoiding communication interruptions, but the complexity of the calibration circuit increases
Solution Approach 1:
The signal combiner performs multiple functions: it combines signals from all transmit chains for normal MIMO transmission and simultaneously provides the combined output signal for calibration purposes. This multi-functionality allows the same hardware component to serve both transmission and calibration needs, improving productivity without proportionally increasing device complexity.
Solution Approach 2:
The combined output signal acts as an intermediary that carries information from all transmit chains in a unified form. The calibration circuit processes this intermediate combined signal to extract individual chain characteristics and determine pre-distortion parameters, simplifying the calibration process compared to directly accessing individual chain signals while maintaining high throughput.
Data Source
AI summary
A MIMO wireless transceiver includes: antennas, components forming transmit and receive chains coupled to the antennas, a signal combiner, and a predistortion calibration circuit. The transmit chain components include: pre-distorter circuits and power amplifiers (PA)s, The pre-distorter circuits each couple to a transmit chain for pre-distorting an associated signal thereon. The PAs are input coupled to a corresponding transmit chain and output coupled to a corresponding antenna. The signal combiner combines the amplified signals from all of the PAs into a combined output signal. The predistortion calibration circuit includes: a chain isolator circuit to isolate a selected amplified signal of a PA within the combined output signal from the signal combiner and an inverter circuit to determine from the selected amplified signal a mathematical inverse of the associated PA's non-linearity; and to provide corresponding pre-distortion parameters to the corresponding pre-distorter circuit,