Simplified Ray Tracing for the Millimeter Wave Channel: A Performance Evaluation

Millimeter-wave (mmWave) communication is one of the cornerstone innovations of fifth-generation (5G) wireless networks, thanks to the massive bandwidth available in these frequency bands. To correctly assess the performance of such systems, however, it is essential to have reliable channel models, based on a deep understanding of the propagation characteristics of the mmWave signal. In this respect, ray tracers can provide high accuracy, at the expense of a significant computational complexity, which limits the scalability of simulations. To address this issue, in this paper we present possible simplifications that can reduce the complexity of ray tracing in the mmWave environment, without significantly affecting the accuracy of the model. We evaluate the effect of such simplifications on link-level metrics, testing different configuration parameters and propagation scenarios.Comment: 6 pages, 6 figures, 1 table. This paper has been accepted for presentation at ITA 2020. (c) 2020 IEEE. Please cite it as: M. Lecci, P. Testolina, M. Giordani, M. Polese, T. Ropitault, C. Gentile, N. Varshney, A. Bodi, M. Zorzi, "Simplified Ray Tracing for the Millimeter Wave Channel: A Performance Evaluation," Information Theory and Applications Workshop (ITA), San Diego, US, 202

On the behavior of transport protocols over IIoT environments

RESUMEN: QUIC es un protocolo de transporte encriptado, multiplexado y de baja latencia promovido por Google y diseñado desde cero para abordar las limitaciones del protocolo TCP, que es la solución que se ha venido utilizando de manera más habitual. Sin embargo, QUIC ha sido diseñado principalmente para servicios web, por lo que su uso en entornos IIoT no ha sido suficientemente analizado, resultando particularmente interesante caracterizar su rendimiento cuando se utiliza en estos escenarios. En este proyecto se analiza el desempeño de QUIC como alternativa de transporte para IIoT, utilizando el protocolo MQTT, así como el papel de los algoritmos de control de congestión, que implementan un conjunto de técnicas para evitar situaciones de saturación en la red y recuperar datos en caso de pérdida. En ese sentido, Google propuso recientemente BBR para reemplazar los algoritmos tradicionales de control de congestión basados en pérdidas, como NewReno o CUBIC, con el objetivo de incrementar el rendimiento y reducir la latencia. Sin embargo, muchos estudios han puesto de manifiesto problemas de rendimiento de BBR, como la poco equidad en el reparto de capacidad entre flujos con diferentes RTT, o al compartir el canal con algoritmos basados en pérdidas como CUBIC. En la memoria se realiza, en primer lugar, una revisión del estado del arte, en la que se analiza el funcionamiento de los protocolos implicados. A continuación se ha empleado el simulador ns-3 para comparar el desempeño de QUIC con el observado al hacer uso del esquema tradicional TCP/TLS, así como las diferencias entre los algoritmos de control de congestión. Se han simulado diferentes tecnologías de red, y los resultados obtenidos ponen de manifiesto que QUIC ofrece un buen rendimiento, lo que permitiría su adopción en escenarios IIoT.ABSTRACT: QUIC is an encrypted, multiplexed, and low-latency transport protocol promoted by Google and designed from the ground up to tackle the limitations of the traditional TCP. However, QUIC use in IIoT environments is not widespread, and it is therefore interesting to characterize its performance when in over such scenarios. In this project, the performance of QUIC as a transport alternative for IIoT based on MQTT is analyzed, as well as the role of congestion control algorithms, which propose a set of techniques to avoid saturation situations in the network and recover from data losses. In that sense, Google recently proposed BBR to replace traditional loss-based congestion control algorithms, such as NewReno or CUBIC, to achieve high performance and low latency. However, many studies have reported performance issues in BBR operation, such as unfairness between flows with different RTTs or sharing the channel with loss-based algorithms. In order to introduce the information in a clear way, an analysis of the state of the art is first carried out in which the operation of the protocols involved is briefly analyzed and explained. The ns-3 simulator is then used to compare the performance of QUIC with that exhibited by the traditional TCP/TLS scheme, as well as the differences between the congestion control algorithms. Different network technologies are simulated, evincing that QUIC yields good performances in configurations resembling IIoT scenarios.Grado en Ingeniería de Tecnologías de Telecomunicació