1-bit ADC DC Offset and CFO Estimation in mmWave Systems
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Solution Overview
Problem
The challenges in 5G mmWave and sub-mmWave communications include increased power consumption, limited range, signal attenuation due to atmospheric and material losses, and the complexity of integrating multiple antennas for beamforming, particularly with the use of low-precision ADCs which complicate carrier-frequency-offset (CFO) and channel estimation.
Innovation Solution
The implementation of joint carrier frequency offset and channel estimation techniques for wideband wireless communications using low-precision ADCs, along with DC offset and power estimation with threshold adjustable 1-bit ADCs, and mixed-signal processing for joint equalization and non-linearity mitigation, enables efficient power management and signal processing in mmWave and sub-mmWave systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If low-precision ADCs are used in mmWave and sub-mmWave systems, then power consumption is reduced, but carrier-frequency-offset (CFO) and channel estimation become very difficult due to strong nonlinearity
Solution Approach 1:
The patent introduces a non-linear pre-distortion processing stage before the ADC that acts as an intermediary to compensate for the ADC's quantization nonlinearity. This pre-distortion processing transforms the input signal in a way that anticipates and counteracts the non-linear effects, enabling accurate CFO and channel estimation even with low-precision ADCs.
Solution Approach 2:
The patent changes the parameter of ADC precision from high to low (1-bit or few-bit ADCs) to reduce power consumption, and compensates for the resulting nonlinearity through digital signal processing techniques that modify the signal parameters in the digital domain to achieve the desired estimation accuracy.
2Strength
If multiple antennas are integrated for beamforming to maintain signal strength, then spatial coverage is improved, but device complexity and spatial diversity requirements increase
Solution Approach 1:
The patent combines multiple antenna elements into a unified beamforming system that processes signals from multiple antennas simultaneously. By merging the antenna elements and their processing chains into an integrated beamforming architecture, the system achieves improved signal strength and spatial coverage while managing complexity through unified processing.
3Measurement precision
If conventional CFO estimation techniques are used in wideband communication systems, then estimation may function in traditional systems, but they fail in wideband systems with low-precision ADCs due to different signal distribution and synchronization imperfection effects
Solution Approach 1:
The patent modifies the CFO estimation approach by changing the signal processing parameters to account for wideband characteristics and low-precision ADC effects. The estimation algorithm is adapted to work with the altered signal distribution and quantization patterns inherent in wideband systems using 1-bit or few-bit ADCs.
Solution Approach 2:
The patent performs preliminary non-linear pre-distortion processing on the received signal before CFO and channel estimation. This preliminary action prepares the signal by compensating for quantization effects in advance, making the subsequent estimation processes effective despite the limitations of low-precision ADCs in wideband systems.
Data Source
AI summary
Millimeter-wave (mmWave) and sub-mmWave technology, apparatuses, and methods that relate to transceivers and receivers for wireless communications are described. The various aspects include an apparatus of a communication device including one or more antennas configured to receive an RF signal and an ADC system. The ADC system includes a 1-bit ADC configured to receive the RF signal, and an ADC controller circuitry configured to measure a number of positive samples in the received RF signal for a plurality of thresholds of the 1-bit ADC, estimate receive signal power associated with the received RF signal based on the measured number of positive samples, determine a direct current (DC) offset in the received RF signal using the estimated received signal power, and adjust the received RF signal based on the determined DC offset.