Millimeter-Wave Human Blockage at 73 GHz with a Simple Double Knife-Edge Diffraction Model and Extension for Directional Antennas (1607.00226v3)

Abstract: This paper presents 73 GHz human blockage measurements for a point-to-point link with a 5 m transmitter-receiver separation distance in an indoor environment, with a human that walked at a speed of approximately 1 m/s at a perpendicular orientation to the line between the transmitter and receiver, at various distances between them. The experiment measures the shadowing effect of a moving human body when using directional antennas at the transmitter and receiver for millimeter-wave radio communications. The measurements were conducted using a 500 Megachips-per-second wideband correlator channel sounder with a 1 GHz first null-to-null RF bandwidth. Results indicate high shadowing attenuation is not just due to the human blocker but also is due to the static directional nature of the antennas used, leading to the need for phased-array antennas to switch beam directions in the presence of obstructions and blockages at millimeter-waves. A simple model for human blockage is provided based on the double knife-edge diffraction (DKED) model where humans are approximated by a rectangular screen with infinite vertical height, similar to the human blockage model given by the METIS project.

• The paper investigates human blockage at 73 GHz, providing experimental data showing over 30 dB shadowing loss and introducing a simple double knife-edge diffraction (DKED) model.
• It demonstrates that a standard DKED model is insufficient for directional antennas, proposing a modification that integrates the antenna radiation pattern for better simulation accuracy.
• The findings underscore the critical need for advanced techniques like dynamic beamforming with phased-array antennas to mitigate significant human blockage effects in mmWave systems.

Analysis of Millimeter-Wave Human Blockage at 73 GHz in Wireless Communications

This paper investigates the impact of human blockage on millimeter-wave (mmWave) wireless communication systems, specifically focusing on a 73 GHz frequency. It provides experimental data and a diffraction model to understand the implications of human interference in a 5G network environment. The paper is particularly relevant as mmWave frequencies, given their potential bandwidth, are critical for future communication systems but are challenged by propagation issues like high attenuation.

Key Research Findings

The research measures the impact of a single human obstructing a line-of-sight (LOS) path in a 5-meter point-to-point link environment using high-gain directional antennas. Significant findings from the experiments include:

• Shadowing Measurement: Human blockage in the LOS path can induce shadowing attenuation exceeding 30 dB. This highlights the significant shadowing effect caused not just by the human body but also by the directional characteristics of the antennas.
• Modeling Approach: The paper introduces a simple double knife-edge diffraction (DKED) model for simulating human blockage effects. The model treats a human as a rectangular screen with infinite height, which aligns with methodologies proposed by the METIS project.
• Model Adaptation for Directional Antennas: The original DKED model was insufficient when accounting for the high directivity of the used antennas. Hence, a modified DKED model was introduced, incorporating the antenna's radiation pattern to better simulate the actual blockage scenario observed in measurements.

Theoretical and Practical Implications

• Theoretical Contribution: This paper advances the theoretical understanding of human-induced signal attenuation at mmWave frequencies. By refining the DKED model to incorporate antenna beam width, the research provides a more accurate tool for simulating real-world communication scenarios involving human obstructions.
• Practical Implications: The findings underscore the importance of incorporating adaptive and dynamic beamforming strategies in mmWave systems to mitigate the effects of human blockage. Specifically, phased-array antennas capable of rapidly switching beams to alternative paths are essential to maintaining consistent connection quality in environments subject to frequent blockages.

Future Directions

In light of these findings, several future research avenues are suggested:

• Complex Environment Modeling: Extending the blockage model to incorporate multiple obstructions and varying scenarios (e.g., dynamic environments with multiple moving individuals) could provide comprehensive insights into real-world challenges.
• Technology Development: Advancements in phased-array antenna technology and its integration in consumer devices could significantly mitigate the attenuation issues highlighted by this research.
• Hybrid Model Integration: Combining the DKED model with other propagation models might provide a more holistic understanding of the various factors affecting mmWave links in complex urban settings.

Conclusion

This paper highlights significant challenges and solutions associated with the deployment of mmWave communication systems in environments with potential obstructions. By providing an enhanced model for understanding human blockage impacts, the research paves the way for more robust and reliable 5G and future wireless communication systems. The insights gained here are crucial for network designers and engineers working to optimize mmWave systems for seamless operation in diverse environments.