Performance Comparison of Dual Connectivity and Hard Handover for LTE-5G Tight Integration in mmWave Cellular Networks

MmWave communications are expected to play a major role in the Fifth generation of mobile networks. They offer a potential multi-gigabit throughput and an ultra-low radio latency, but at the same time suffer from high isotropic pathloss, and a coverage area much smaller than the one of LTE macrocells. In order to address these issues, highly directional beamforming and a very high-density deployment of mmWave base stations were proposed. This Thesis aims to improve the reliability and performance of the 5G network by studying its tight and seamless integration with the current LTE cellular network. In particular, the LTE base stations can provide a coverage layer for 5G mobile terminals, because they operate on microWave frequencies, which are less sensitive to blockage and have a lower pathloss. This document is a copy of the Master's Thesis carried out by Mr. Michele Polese under the supervision of Dr. Marco Mezzavilla and Prof. Michele Zorzi. It will propose an LTE-5G tight integration architecture, based on mobile terminals' dual connectivity to LTE and 5G radio access networks, and will evaluate which are the new network procedures that will be needed to support it. Moreover, this new architecture will be implemented in the ns-3 simulator, and a thorough simulation campaign will be conducted in order to evaluate its performance, with respect to the baseline of handover between LTE and 5G.Comment: Master's Thesis carried out by Mr. Michele Polese under the supervision of Dr. Marco Mezzavilla and Prof. Michele Zorz

Les défis de l'émulation Wi-Fi à base des traces

Wi-Fi link is unpredictable and it has never been easy to measure it perfectly; there is always bound to be some bias. As wireless becomes the medium of choice, it is useful to capture Wi-Fi traces in order to evaluate, tune, and adapt the different applications and protocols. Several methods have been used for the purpose of experimenting with different wireless conditions: simulation, experimentation, and trace-driven emulation. In this paper, we argue that trace-driven emulation is the most favourable approach. In the absence of a trace-driven emulation tool for Wi-Fi, we evaluate the state-of-the-art trace driven emulation tool for Cellular networks and we identify issues for Wi-Fi: interference with concurrent traffic, interference with its own traffic if measurements are done on both uplink and downlink simultaneously , and packet loss. We provide a solid argument as to why this tool falls short from effectively capturing Wi-Fi traces. The outcome of our analysis guides us to propose a number of suggestions on how the existing tool can be tweaked to accurately capture Wi-Fi traces.La liaison Wi-Fi est imprévisible et il n'a jamais été facile de la mesurer parfaitement ; il y a toujours un risque de biais. Comme le sans fil devient le moyen de communication de choix, il est utile de capturer les traces Wi-Fi afin d'évaluer, de régler et d'adapter les différentes applications et protocoles. Plusieurs méthodes ont été utilisées pour expérimenter différentes conditions sans fil : la simulation, l'expérimentation et l'émulation de traces. Dans cet article, nous soutenons que l'émulation pilotée par les traces est l'approche la plus favorable. En l'absence d'un outil d'émulation piloté par trace pour le Wi-Fi, nous évaluons l'outil d'émulation piloté par trace de pointe pour les réseaux cellulaires et nous identifions les problèmes pour le Wi-Fi : interférence avec le trafic concurrent, interférence avec son propre trafic si les mesures sont effectuées simultanément sur la liaison montante et la liaison descendante, et perte de paquets. Nous fournissons un argument solide pour expliquer pourquoi cet outil ne parvient pas à capturer efficacement les traces Wi-Fi. Le résultat de notre analyse nous guide pour proposer un certain nombre de suggestions sur la manière dont l'outil existant peut être modifié pour capturer avec précision les traces Wi-Fi

Operations and Results from the 200 Gbps TBIRD Laser Communication Mission

Since launch in May 2022, the TeraByte Infrared Delivery (TBIRD) mission has successfully demonstrated 200 Gbps laser communications from a 6U CubeSat and has transferred up to 4.8 terabytes (TB) in a pass from low Earth orbit to ground. To our knowledge, this is the fastest downlink ever achieved from space. To support the narrow downlink beam required for high rate communications, the payload provides pointing feedback to the host spacecraft to precisely track the ground station throughout the 5-minute pass. The space and ground terminals utilize fiber-coupled coherent transceivers in conjunction with an automatic repeat request (ARQ) system to guarantee error-free communication through an atmospheric fading channel. This paper presents an overview of the link operations and mission results to date, as well as implications for future missions with high rate lasercom