Full-Duplex Transceiver System Calculations: Analysis of ADC and Linearity Challenges

Abstract: Despite the intensive recent research on wireless single-channel full-duplex communications, relatively little is known about the transceiver chain nonidealities of full-duplex devices. In this paper, the effect of nonlinear distortion occurring in the transmitter power amplifier (PA) and the receiver chain is analyzed, alongside with the dynamic range requirements of analog-to-digital converters (ADCs). This is done with detailed system calculations, which combine the properties of the individual electronics components to jointly model the complete transceiver chain, including self-interference cancellation. They also quantify the decrease in the dynamic range for the signal of interest caused by self-interference at the analog-to-digital interface. Using these system calculations, we provide comprehensive numerical results for typical transceiver parameters. The analytical results are also confirmed with full waveform simulations. We observe that the nonlinear distortion produced by the transmitter PA is a significant issue in a full-duplex transceiver and, when using cheaper and less linear components, also the receiver chain nonlinearities become considerable. It is also shown that, with digitally-intensive self-interference cancellation, the quantization noise of the ADCs is another significant problem.

• The paper details how ADC quantization noise and PA nonlinear distortion, particularly IMD3, impair full-duplex system performance.
• It uses analytical and simulation methods to show that transmit powers above ~15 dBm exacerbate interference due to limited ADC dynamic range.
• The study highlights the need for advanced SI cancellation and improved hardware design to mitigate nonidealities in full-duplex transceivers.

Analysis of ADC and Linearity Challenges in Full-Duplex Transceiver Systems

The paper "Full-Duplex Transceiver System Calculations: Analysis of ADC and Linearity Challenges" provides an in-depth examination of the transceiver chain nonidealities in full-duplex (FD) communication systems. It highlights the impacts of nonlinear distortion in transmitter power amplifiers (PAs) and receiver chains, alongside the dynamic range requirements of analog-to-digital converters (ADCs). This nuanced understanding is critical as assumptions of ideal electronic components often do not hold in practical implementations.

Key Findings and Numerical Results

The authors present detailed analytical and simulation results characterizing the various signal distortions encountered in full-duplex transceivers. They observed that the nonlinear distortion caused by the PA becomes a significant problem, especially when using cost-effective components with lesser linearity. Specifically, PA-generated third-order intermodulation distortion (IMD3) can dominate the interference landscape if not properly canceled or managed.

The study also explores the ADC dynamic range, finding the quantization noise to be a considerable issue, mainly when digitally-intensive self-interference (SI) cancellation is used. For transmit powers beyond a certain threshold (approximately 15 dBm in typical scenarios), quantization noise and insufficient dynamic range of the ADC become the limiting factors in maintaining a satisfactory signal-to-interference-plus-noise ratio (SINR).

Implications

The research implications are robust, affecting both theoretical and practical domains of wireless communication. The paper highlights the importance of ensuring sufficient linearity in transceiver components and adequate ADC dynamic range to mitigate distortion effects in full-duplex systems. This could influence future designs and standards for transceiver hardware, necessitating advanced SI cancellation techniques, including both linear and nonlinear methodologies.

Future Developments

The paper speculates on the potential benefits of incorporating nonlinear digital cancellation techniques. As the quest for higher spectral efficiency intensifies, it is foreseeable that further advancements in hardware architecture and digital processing algorithms will be essential. The development of full-duplex systems capable of handling high-power transmission requires more sophisticated RF and ADC technologies focusing on mitigating nonlinear effects and improving dynamic range capabilities.

Overall, this paper contributes significantly to the understanding of full-duplex transceiver design challenges, providing a foundation for future research in enhancing the efficacy of wireless communication systems under realistic nonidealities. The exploration of nonlinear effects and ADC limitations continues to be a critical focus area, promising ongoing refinements in full-duplex technology implementations.