Analysis and performance improvement of consumer-grade millimeter wave wireless networks

Millimeter-wave (mmWave) networks are one of the main key components in next cellular and WLANs (Wireless Local Area Networks). mmWave networks are capable of providing multi gigabit-per-second rates with very directional low-interference and high spatial reuse links. In 2013, the first 60 GHz wireless solution for WLAN appeared in the market. These were wireless docking stations under theWiGig protocol. Today, in 2019, 60 GHz communications have gained importance with the IEEE 802.11ad amendment with different products on the market, including routers, laptops and wireless Ethernet solutions. More importantly, mmWave networks are going to be used in next generation cellular networks, where smartphones will be using the 28 GHz band. For backbone links, 60 GHz communications have been proposed due to its higher directionality and unlicensed use. This thesis fits in this frame of constant development of themmWave bands to meet the needs of latency and throughput that will be necessary to support future communications. In this thesis, we first characterize the cost-effective design of COTS (commercial off-the-shelf) 60 GHz devices and later we improve their two main weaknesses, which are their low link distance and their non-ideal spatial reuse. It is critical to take into consideration the cost-effective design of COTS devices when designing networking mechanisms. This is why in this thesis we do the first-of-its-kind COTS analysis of 60 GHz devices, studying the D5000 WiGig Docking station and the TP-Link Talon IEEE 802.11ad router. We include static measurements such as the synthesized beam patterns of these devices or an analysis of the area-wide coverage that these devices can fulfill. We perform a spatial reuse analysis and study the performance of these devices under user mobility, showing how robust the link can be under user movement. We also study the feasibility of having flying mmWave links. We mount a 60 GHz COTS device into a drone and perform different measurement campaigns. In this first analysis, we see that these 60 GHz devices have a large performance gap for the achieved communication range as well as a very low spatial reuse. However, they are still suitable for low density WLANs and for next generation aerial micro cell stations. Seeing that these COTS devices are not as directional as literature suggests, we analyze how channels are not as frequency stable as expected due to the large amount of reflected signals. Ideally, frequency selective techniques could be used in these frequency selective channels in order to enlarge the range of these 60 GHz devices. To validate this, we measure real-world 60 GHz indoor channels with a bandwidth of 2 GHz and study their behavior with respect to techniques such as bitloading, subcarrier switch-off, and waterfilling. To this end, we consider a Orthogonal Frequency-Division Multiplexing (OFDM) channel as defined in the IEEE 802.11ad standard and show that in point of fact, these techniques are highly beneficial in mmWave networks allowing for a range extension of up to 50%, equivalent to power savings of up to 7 dB. In order to increase the very limited spatial reuse of these wireless networks, we propose a centralized system that allows the network to carry out the beam training process not only to maximize power but also taking into account other stations in order to minimize interference. This system is designed to work with unmodified clients. We implement and validate our system on commercial off-the-shelf IEEE 802.11ad hardware, achieving an average throughput gain of 24.67% for TCP traffic, and up to a twofold throughput gain in specific cases.Programa de Doctorado en Multimedia y Comunicaciones por la Universidad Carlos III de Madrid y la Universidad Rey Juan CarlosPresidente: Andrés García Saavedra.- Secretario: Matilde Pilar Sánchez Fernández.- Vocal: Ljiljana Simi

Characterization of wireless millimeter wave systems considering the impact of reflections and imperfect beam patterns

Communication on millimeter Wave (mm-Wave) frequencies is a key technology for next generation wireless networks. It allows multi-gigabit link speeds in highly crowded network scenarios, by leveraging directional communication. Due to quasi-optical propagation characteristics at mm- Wave frequencies, most works in scientific literature simplify directional links in that band to sharp-edged line of sight beams. However, measurements have identified certain objects to pose strong reflectors, rendering the former assumption unrealistic. This thesis, analyses the impact of reflections and beam side-lobes on mm-Wave networks and studies the resulting impact on interference and coverage. To this aim, reflections and side lobes of off-the-shelf 60 GHz systems are analyzed in an extensive measurement campaign to then verify the established assumptions on mm-Wave propagation. Further, this work analyzes the frame flow of the used protocols to extract the general communication behaviour of the off-the-shelf 60 GHz system.Ingeniería de Sistemas de Comunicacione

IV consenso mexicano sobre Helicobacter pylori

Desde el último consenso mexicano para el diagnóstico y tratamiento de la infección por Helicobacter pylori (H. pylori) en el 2007, han existido avances importantes al respecto. Por tal motivo, la Asociación Mexicana de Gastroenterología convocó a 20 expertos para la realización del «IV consenso mexicano sobre H. pylori». Durante febrero y junio del 2017 se organizaron 4 mesas de trabajo, una revisión de la literatura y 3 rondas de votaciones donde se establecieron 32 enunciados para discusión y consenso. Dentro de las recomendaciones se destaca el reconocer a México como un país con riesgo de cáncer gástrico bajo a intermedio a pesar de la alta prevalencia de infección por H. pylori. Se corrobora que enfermedad ulcerosa péptica, presencia de lesiones premalignas, antecedentes de cáncer gástrico y linfoma asociado a la mucosa deben considerarse indicaciones claras para erradicación. La relación del H. pylori con los síntomas dispépticos sigue siendo controversial. La triple terapia de erradicación con amoxicilina, claritromicina y un inhibidor de la bomba de protones ya no debe ser considerada la primera línea de tratamiento. En su lugar, se proponen 2 opciones: la terapia cuádruple con bismuto (inhibidor de la bomba de protones, subcitrato de bismuto, tetraciclina y metronidazol) y la terapia cuádruple sin bismuto (inhibidor de la bomba de protones, amoxicilina, claritromicina y metronidazol). Se establece la necesidad de la realización de sensibilidad antimicrobiana ante la falla a 2 tratamientos de erradicación. Finalmente, se proponen campañas de educación respecto al diagnóstico y tratamiento del H. pylori para médicos de primer contacto y población general. Abstract Important advances have been made since the last Mexican consensus on the diagnosis and treatment of Helicobacter pylori (H. pylori) infection was published in 2007. Therefore, the Asociación Mexicana de Gastroenterología summoned 20 experts to produce ‘‘The Fourth Mexican Consensus on Helicobacter pylori’’. From February to June 2017, 4 working groups were organized, a literature review was performed, and 3 voting rounds were carried out, resulting in the formulation of 32 statements for discussion and consensus. From the ensuing recommendations, it was striking that Mexico is a country with an intermediate-to-low risk for gastric cancer, despite having a high prevalence of H. pylori infection. It was also corroborated that peptic ulcer disease, premalignant lesions, and histories of gastric cancer and mucosaassociated lymphoid tissue lymphoma should be considered clear indications for eradication. The relation of H. pylori to dyspeptic symptoms continues to be controversial. Eradication triple therapy with amoxicillin, clarithromycin, and a proton pump inhibitor should no longer be considered first-line treatment, with the following 2 options proposed to take its place: quadruple therapy with bismuth (proton pump inhibitor, bismuth subcitrate, tetracycline, and metronidazole) and quadruple therapy without bismuth (proton pump inhibitor, amoxicillin, clarithromycin, and metronidazole). The need for antimicrobial sensitivity testing when 2 eradication treatments have failed was also established. Finally, the promotion of educational campaigns on the diagnosis and treatment of H. pylori for both primary care physicians and the general population were proposed