Reflexions sobre l'aportació de la química analítica a l'estudi del medi ambient

La contaminació sol expressar-se en espècies químiques concretes, cosa que indueix una relació reversible entre la contaminació i la Química, donant lloc a nombrosos equívocs, com és el cas que alguns químics analistes prenen la iniciativa per a dissenyar estudis i interpretar resultats, recolzats en la capacitat de l'instrumental de mesura, quan, en realitat, són qüestions multidisciplinàries, molt complexes. El punt de vista químic dóna una referència important, que cal valorar oportunament dins el context general de la qüestió ambiental. Aquesta valoració s'ha de fer en termes de fiabilitat dels resultats de laboratori i de ]a mostra objecte de mesura, respecte a la seva representativitat d'un lloc o d'una situació concreta. Es consideren algunes possibilitats per a garantir la fiabilitat, mitjançant tècniques, com el disseny d'experiència, els exercicis d'intercalibració entre laboratoris, i els mètodes avançats per al tractament i presentació de resultats. Hem cregut que podria interessar de conèixer algunes idees a les quals hem arribat, després de participar en projectes de seguiment i de desenvolupar estudis metodològics per a la determinació de contaminants en el Medi Ambient. Aquesta línia de treball fou adoptada per a adjuntar, en un tema comú, les diferentes especialitats del Departament d'Analítica i per a participar en projectes multi disciplinaris i multinacionals

WizHaul: An Automated Solution for vRAN Deployments Optimization

Future 5G deployments will support a flexible split of Base Station (BS) functions, i.e., it will be possible to decide which atomic operations will be co-located on the edge and which ones will be processed on a Central Unit (CU). Thus, network owners will be able to decide how much centralization they would like to retain in different deployments. However, deciding which BS components should be offloaded to a CU becomes a challenge because routing and BS function placement choices are coupled. We present WizHaul, a software framework enabling the implementation of a centralized functional split decision- making engine for future 5G networks. The purpose of WizHaul is twofold. First, it may be used in a network planning phase to settle the optimal amount of centralization. Second, it may also be used to support network automation/adaptation scenarios where network failures or congestion in the cloud may draw the current configuration infeasible.This work has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 761536 (5G-Transformer project)

WizHaul: On the Centralization Degree of Cloud RAN Next Generation Fronthaul

Cloud Radio Access Network (C-RAN) will become a main building block for 5G. However, the stringent requirements of current fronthaul solutions hinder its large-scale deployment. In order to introduce C-RAN widely in 5G, the next generation fronthaul \agsrev{interface} (NGFI) will be based on a cost-efficient packet-based network with higher path diversity. In addition, NGFI shall support a flexible functional split of the RAN to adapt the amount of centralization to the capabilities of the transport network. In this paper we question the ability of standard techniques to route NGFI traffic while maximizing the centralization degree---the goal of C-RAN. We propose two solutions jointly addressing both challenges: (i) a nearly-optimal backtracking scheme, and (ii) a low-complex greedy approach. We first validate the feasibility of our approach in an experimental proof-of-concept, and then evaluate both algorithms via simulations in large-scale (real and synthetic) topologies. Our results show that state-of-the-art techniques fail at maximizing the centralization degree and that the achievable C-RAN centralization highly depends on the underlying topology structure.This work has received funding from the European Unions Horizon 2020 research and innovation programme under grant agreement No 671598 (5G-Crosshaul project) and 761536 (5G-Transformer project)

Overbooking Network Slices End-to-End: Implementation and Demonstration

This paper has been presented at: ACM SIGCOMM 2018 Conference on Posters and DemosThe novel network slicing paradigm allows service providers to open their infrastructure to new business players such as vertical industries. In this demo, we showcase the benefits of our proposed end-to-end network slicing orchestration solution that blends together i) an admission control engine able to handle heterogeneous network slice requests, ii) a resource allocation solution across multiple network domains: radio access, edge, transport and core networks and iii) a monitoring, forecasting and dynamic configuration solution that maximizes the statistical multiplexing of network slices resources. Our orchestration solution is operated through a dashboard that allows requesting network slices on-demand, monitors their performance once deployed and displays the achieved multiplexing gain through overbooking

Overbooking Network Slices through Yield-driven End-to-End Orchestration

Proceeding of: 14th International Conference on emerging Networking EXperiments and Technologies (CoNEXT '18)Network slicing allows mobile operators to offer, via proper abstractions, mobile infrastructure (radio, networking, computing) to vertical sectors traditionally alien to the telco industry (e.g., automotive, health, construction). Owning to similar business nature, in this paper we adopt yield management models successful in other sectors (e.g. airlines, hotels, etc.) and so we explore the concept of slice overbooking to maximize the revenue of mobile operators. The main contribution of this paper is threefold. First, we design a hierarchical control plane to manage the orchestration of slices end-to-end, including radio access, transport network, and distributed computing infrastructure. Second, we cast the orchestration problem as a stochastic yield management problem and propose two algorithms to solve it: an optimal Benders decomposition method and a suboptimal heuristic that expedites solutions. Third, we implement an experimental proof-of-concept and assess our approach both experimentally and via simulations with topologies from three real operators and a wide set of realistic scenarios. Our performance evaluation shows that slice overbooking can provide up to 3x revenue gains in realistic scenarios with minimal footprint on service-level agreements (SLAs).This work was supported in part by the H2020 5G-Transformer Project under Grant 761536 and in part by H2020-MSCA-ITN-2015 5G-Aura Project under Grant 675806

Latency-driven Network Slices Orchestration

This paper has been presented at: IEEE Conference on Computer Communications Workshops ( INFOCOM'19 )The novel concept of network slicing is envisioned to allow service providers to open their infrastructure to vertical industries traditionally alien to mobile networks, such as automotive, health or factories. In this way multiple vertical services can be delivered over the same physical facilities by means of advanced network virtualization techniques. However, the vertical service requirements heterogeneity (e.g., high throughput, low latency, high reliability) calls for novel orchestration solutions able to manage end-to-end network slice resources across different domains while satisfying stringent service level agreements. In this demonstration we will show a novel orchestration solution able to handle one of the most stringent requirements: end-to-end latency. Our testbed-evolution of the work presented in [1]-implements all the resource brokerage schemes and allocation operations necessary to complete the life-cycle management of network slices. In addition, the novel overbooking concept is applied to pursue the overall revenue maximization when admitting network slices. Finally, an advanced network slicing monitoring system will be provided as a user-friendly dashboard allowing users to interact with the proposed solution.This work was supported by the H2020 5G-Transformer Project under Grant 761536 and by the H2020-MSCA-ITN-2015 5G-AURA Project under Grant 675806

5G-TRANSFORMER Service Orchestrator: design, implementation, and evaluation

European Conference on Networks and Communications (EuCNC 2019)5G networks will pose complex network management challenges due to the variety of vertical services they will need to serve and the diversity and heterogeneity of underlying infrastructure. The service orchestration functionality is fundamental to enable fulfilling the requirements of the different verticals while efficiently sharing the infrastructure resources. This paper details the 5G-TRANSFORMER service orchestrator implementation and operation. It also evaluates and profiles service creation time showing how the automation offered by the platform allows reducing it from hours to minutes. It also shows that the most time-consuming steps correspond to the deployment of the virtual network functions and post-deployment configuration, which consume one order of magnitude more time than the rest of steps (e.g., network creation, port creation).This work has been partially funded by the EC H2020 5G-TRANSFORMER Project (grant no. 761536) and grants TEC2017-88373-R (5G-REFINE) and 2017 SGR 1195

Effectiveness of Thrombectomy in Stroke According to Baseline Prognostic Factors: Inverse Probability of Treatment Weighting Analysis of a Population-Based Registry

Background and Purpose In real-world practice, the benefit of mechanical thrombectomy (MT) is uncertain in stroke patients with very favorable or poor prognostic profiles at baseline. We studied the effectiveness of MT versus medical treatment stratifying by different baseline prognostic factors. Methods Retrospective analysis of 2,588 patients with an ischemic stroke due to large vessel occlusion nested in the population-based registry of stroke code activations in Catalonia from January 2017 to June 2019. The effect of MT on good functional outcome (modified Rankin Score 85 years, National Institutes of Health Stroke Scale [NIHSS] >25, time from onset >6 hours, Alberta Stroke Program Early CT Score 3), good (if NIHSS <6 or distal occlusion, in the absence of poor prognostic factors), or reference (not meeting other groups' criteria). Results Patients receiving MT (n=1,996, 77%) were younger, had less pre-stroke disability, and received systemic thrombolysis less frequently. These differences were balanced after the IPTW stratified by prognosis. MT was associated with good functional outcome in the reference (odds ratio [OR], 2.9; 95% confidence interval [CI], 2.0 to 4.4), and especially in the poor baseline prognostic stratum (OR, 3.9; 95% CI, 2.6 to 5.9), but not in the good prognostic stratum. MT was associated with survival only in the poor prognostic stratum (OR, 2.6; 95% CI, 2.0 to 3.3). Conclusions Despite their worse overall outcomes, the impact of thrombectomy over medical management was more substantial in patients with poorer baseline prognostic factors than patients with good prognostic factors

Orquestració i gestió d'avaries de les infraestructures en el futur 5G-backhaul

RAN (Radio Access Network) centralization has been presented as an attractive solution for 5G. However, the rigid requirements of nowadays fronthaul networks, which connect radio heads and computing platforms, hinder its deployment in large-scale systems. To relax these constraints, the next generation fronthaul interface (NGFI) should be able to cope with a flexible split of the RAN functions, adapting the degree of centralization to the capabilities of the transport network. NGFI should also be able to exploit statistical multiplexing and higher degrees of freedom when transporting data across the fronthaul. Despite its advantages, in this thesis we question the ability of standard techniques to properly route fronthaul traffic while optimizing the RAN functional split. In light of this, we propose addressing both problems jointly and devise two algorithms: an heuristic greedy approach and a nearly-optimal backtracking scheme. We compare them via simulations with legacy strategies for a large set of random and real topologies and show that we obtain low degree of centralization when the problem is not tackled jointly.RAN (Red de Acceso Radio) centralización se ha presentado como una solución atractiva para 5G. Sin embargo, los estrictos requisitos de las redes de hoy en día fronthaul, que conectan cabeceras de radio y plataformas informáticas, obstaculizan su despliegue en sistemas a gran escala. Para relajar estas limitaciones, la interfaz fronthaul próxima generación (NGFI) debe ser capaz de hacer frente a un partido flexible de las funciones RAN, adaptando el grado de centralización de las capacidades de la red de transporte. NGFI también debe ser capaz de explotar la multiplexación estadística y mayores grados de libertad en el transporte de datos a través de la fronthaul. A pesar de sus ventajas, en esta tesis ponemos en duda la capacidad de las técnicas estándar para el tráfico fronthaul ruta correctamente, mientras que la optimización de la división funcional RAN. A la luz de esto, se propone abordar ambos problemas de manera conjunta e idear dos algoritmos: un enfoque codiciosos heurística y un esquema de retroceso de casi óptima. Las comparamos a través de simulaciones con las estrategias existentes para un gran conjunto de topologías de azar y reales y mostrar que se obtiene bajo grado de centralización cuando el problema no se aborda de manera conjunta.RAN (Xarxa d'Accés Ràdio) centralització s'ha presentat com una solució atractiva per 5G. No obstant això, els estrictes requisits de les xarxes d'avui en dia fronthaul, que connecten capçaleres de ràdio i plataformes informàtiques, obstaculitzen el seu desplegament a sistemes a gran escala. Per relaxar aquestes limitacions, la interfície fronthaul pròxima generació (NGFI) ha de poder fer front a un partit flexible de les funcions RAN, adaptant el grau de centralització de les capacitats de la xarxa de transport. NGFI també ha de ser capaç d'explotar la multiplexació estadística i majors graus de llibertat en el transport de dades a través de la fronthaul. Malgrat els seus avantatges, en aquesta tesi posem en dubte la capacitat de les tècniques estàndard per al trànsit fronthaul ruta correctament, mentre que l'optimització de la divisió funcional RAN. A la llum d'això, es proposa abordar els dos problemes de manera conjunta i idear dos algorismes: un enfocament cobdiciosos heurística i un esquema de retrocés de gairebé òptima. Les comparem a través de simulacions amb les estratègies existents per a un gran conjunt de topologies d'atzar i reals i mostrar que s'obté baix grau de centralització quan el problema no s'aborda de manera conjunta