WiFi location systems are remarkably accurate, with decimeterlevel errors for recent CSI-based systems. However, such high accuracy is achieved under Line-of-Sight (LOS) conditions and with an access point (AP) density that is much higher than that typically found in current deployments that primarily target good coverage. In contrast, when many of the APs within range are in Non-Lineof-Sight (NLOS), the location accuracy degrades drastically.In this paper we present UbiLocate, a WiFi location system that copes well with common AP deployment densities and works ubiquitously, i.e., without excessive degradation under NLOS. UbiLocate demonstrates that meter-level median accuracy NLOS localization is possible through (i) an innovative angle estimator based on a Nelder-Mead search, (ii) a fine-grained time of flight ranging system with nanosecond resolution, and (iii) the accuracy improvements brought about by the increase in bandwidth and number of antennas of IEEE 802.11ac. In combination, they provide superior resolvability of multipath components, significantly improving location accuracy over prior work. We implement our location system on off-the-shelf 802.11ac devices and make the implementation, CSI-extraction tool and custom Fine Timing Measurement design publicly available to the research community. We carry out an extensive performance analysis of our system and show that it outperforms current state-of-the-art location systems by a factor of 2-3, both under LOS and NLOS. CCS CONCEPTS• Networks → Location based services.

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A Ph.D. is the culmination of many years of study and effort. It has been undoubtedly one of the most challenging endeavours of my life and, even though a Ph.D is ultimately a single person objective, I was not alone at any point. I have to thank to all those now forgotten teachers from school and high school, and all the friends along the way. More importantly my family, specially my parents and my brother, have been a constant rock all this time, I deeply appreciate that. More recently my family grew, I got married to Eva my awesome wife, to whom I am specially grateful for supporting me through the last years of my Ph.D. I could not have made it without her. I want to extend my sincere thanks to Joerg Widmer, a supervisor is probably the most important figure during a Ph.D. and he was more than up to the task. He guided me through difficult times, with patience and good advice. I also want to extend my gratitude to everyone from IMDEA Networks Institute. People feel so close to you when you are going through challenges that are similar, even if they are not the same. I have enjoyed meeting and getting to know so much people over the years, over coffee breaks

To support next generation services, 5G mobile network architectures are increasingly adopting emerging technlogies like software-defined networking (SDN) and network function virtualization (NFV). Core and radio access functionalities are virtualized and executed in edge data centers, in accordance with the Multi-Access Edge Computing (MEC) principle. While testbeds are an essential research tool for experimental evaluation in such environments, the landscape of data center and mobile network testbeds is fragmented. In this work, we aim at filling this gap by presenting openLEON, an open source muLti-access Edge cOmputiNg end-to-end emulator that operates from the edge data center to the mobile users. openLEON bridges the functionalities of existing emulators for data centers and mobile networks, i.e., Mininet and srsLTE, and makes it possible to evaluate and validate research ideas on all the components of an end-to-end mobile edge architecture. CCS CONCEPTS • Networks → Network architectures; Data center networks; Mobile networks;