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Sixth-generation (6G) network slicing is the backbone of future communications systems. It inaugurates the era of extreme ultra-reliable and low-latency communication (xURLLC) and pervades the digitalization of the various vertical immersive use cases. Since 6G inherently underpins artificial intelligence (AI), we propose a systematic and standalone slice termed SliceOps that is natively embedded in the 6G architecture, which gathers and manages the whole AI lifecycle through monitoring, re-training, and deploying the machine learning (ML) models as a service for the 6G slices. By leveraging machine learning operations (MLOps) in conjunction with eXplainable AI (XAI), SliceOps strives to cope with the opaqueness of black-box AI using explanation-guided reinforcement learning (XRL) to fulfill transparency, trustworthi- ness, and interpretability in the network slicing ecosystem. This article starts by elaborating on the architectural and algorithmic aspects of SliceOps. Then, the deployed cloud-native SliceOps working is exemplified via a latency-aware resource allocation problem. The deep RL (DRL)-based SliceOps agents within slices provide AI services aiming to allocate optimal radio resources and impede service quality degradation. Simulation results demon- strate the effectiveness of SliceOps-driven slicing. The article dis- cusses afterward the SliceOps challenges and limitations. Finally, the key open research directions corresponding to the proposed approach are identified., This work was partially funded by MINECO (Spain) and the EU NextGenerationEU/PRTR (Call UNICO I+D 5G 2021, ref. number TSI-063000-2021-10), SNS-JU projects ADROIT6G (101095363) and 6GBRICKS (101096954)., Peer Reviewed, Postprint (author's final draft)

With the exponential growth of the Internet of Things (IoT), more and more municipalities are incorporating new technologies to effectively manage their resources and improve the quality of life for their citizens. In this context, this work primarily focuses on the development of a LoRaWAN network for the municipality of Vila-seca as part of the effort to transform the municipality into a smart city. The motivation for this project stems from the expressed interest of the Vila-seca City Council in exploring LoRa technology for future projects. The main objective is to verify the functionality and viability of LoRaWAN technology in this particular context. The study encompasses the planning of the technological platform and the management of equipment procurement for its deployment. Additionally, a theoretical coverage study using software has been conducted to evaluate the network's range, as well as an analysis of potential interferences within the municipality. Detailed configurations and processes are explained to establish a functional service, along with field measurements to verify the quality of the service to be provided. Furthermore, the integration of IoT device data management with the blockchain network has been explored to enhance security and data integrity. This involves research into solutions and the implementation of all necessary elements to ensure proper functioning. At the end of the thesis, conclusions based on the obtained results are presented, along with the challenges that arose throughout the project and the solutions implemented to address them. This critical analysis of the work enables reflection on the achieved results and provides recommendations for future work in this field., Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura

The objective of this document is to study and verify the development and improvements in Unmanned Aircraft Systems (UAS) for difficult access environments since this matter is a critical area of research and innovation. As the use of UAS in various applications continues to expand, the need for these systems to operate in challenging environments such as mountainous terrain, dense forests, or urban areas with high-rise structures is increasing. The main motivation to start developing this project was the challenge exposed in the Xprize Rainforest Competition. The $10M XPRIZE Rainforest is a five-year competition to enhance the understanding of the rainforest ecosystem. I am part of the semifinalist team, Providence Plus, a multidisciplinary team composed by scientists from UPC, CSIC, MIT, and TUDelf. The purpose of this challenge is to obtain the maximum amount of information on biodiversity in the rainforest, using drone technology in this type of environment, with all the difficulties inherent in this environment that must be overcome and that are also the subject of analysis in this work, to propose and compare the different solutions and technologies to achieve the objectives of said challenge. As resources for competing in Xprize Challenge are limited and the final solution shall be scalable, the technologies evaluated must be cost efficient and practical. The first difficulty in this kind of environments is the signal strength and signal quality, not only for the drone commands but for the video and telemetry data. In this work, different solutions will be compared since analogic to digital technology. The second difficulty is autonomy, in terms of energetic supply. Taking into account the Rainforest environment and environmental policies, the most suitable technology available is batteries. There are several types of batteries that are suitable for drones, depending on the size, weight, and specifications of the drone. There will be a comparison between the, Objectius de Desenvolupament Sostenible::15 - Vida d'Ecosistemes Terrestres, Objectius de Desenvolupament Sostenible::13 - Acció per al Clima

Recent advancements in vehicle-to-everything (V2X) communication have notably improved existing transport systems by enabling increased connectivity and driving autonomy levels. The remarkable benefits of V2X connectivity come inadvertently with challenges which involve security vulnerabilities and breaches. Addressing security concerns is essential for seamless and safe operation of mission-critical V2X use cases. This paper surveys current literature on V2X security and provides a systematic and comprehensive review of the most relevant security enhancements to date. An in-depth classification of V2X attacks is first performed according to key security and privacy requirements. Our methodology resumes with a taxonomy of security mechanisms based on their proactive/reactive defensive approach, which helps identify strengths and limitations of state-of-the-art countermeasures for V2X attacks. In addition, this paper delves into the potential of emerging security approaches leveraging artificial intelligence tools to meet security objectives. Promising data-driven solutions tailored to tackle security, privacy and trust issues are thoroughly discussed along with new threat vectors introduced inevitably by these enablers. The lessons learned from the detailed review of existing works are also compiled and highlighted. We conclude this survey with a structured synthesis of open challenges and future research directions to foster contributions in this prominent field., This work is supported by the H2020-INSPIRE-5Gplus project (under Grant agreement No. 871808), the ”Ministerio de Asuntos Económicos y Transformacion Digital” and the European Union-NextGenerationEU in the frameworks of the ”Plan de Recuperación, Transformación y Resiliencia” and of the ”Mecanismo de Recuperación y Resiliencia” under references TSI-063000-2021-39/40/41, and the CHIST-ERA-17-BDSI-003 FIREMAN project funded by the Spanish National Foundation (Grant PCI2019-103780)., Peer Reviewed, Postprint (published version)

Tesi amb menció de Doctorat Internacional, (English) The sixth-generation (6G) network's evolution necessitates advancements in algorithms and architecture to transition from an AI-native to an intrinsic trustworthy automation-native system. Network slicing creates multiple virtual networks for diverse service requirements and is a crucial technology for future communication systems and 6G networks. This technology will facilitate numerous aspects of life, society, and industry, meeting the communication needs of both humans and intelligent machines. This is made possible by employing softwarization and virtualization technologies, including software-defined networking (SDN) and network functions virtualization (NFV), to enable the necessary flexibility and programmability required for network slicing. However, the implementation of network slicing in radio access networks (RAN) is challenging due to the complexity of managing RAN operations. This gap is addressed with zero-touch network slicing, a fully automated management and orchestration scheme, which eliminates the need for fixed contracts and manual intervention. The decision engine, a main component of this technology, employs algorithmic innovation to optimize network resource allocation and handle the challenges of RAN slicing, including energy efficiency, latency, scalability, and trustworthiness. In resource allocation, a joint optimization approach is used to balance energy and latency with service quality. A stochastic Actor-Critic approach is proposed to streamline the learning procedure and reduce the need for hyperparameter tuning in an energy-aware network slicing setup. Additionally, a massive deep reinforcement learning-based actor-learner framework is introduced to tackle complexity issues and control challenges in network slicing. The temporal variations of traffic demand pose a significant challenge for resource planning and allocation in the RAN domain. To mitigate this, a distributed architecture for RAN slice resource orchestration, (Español) La evolución hacia la red de sexta generación (6G) requiere avances en algoritmos y arquitectura para pasar de un sistema nativo de IA a un sistema nativo de automatización intrínsecamente confiable. El slicing de red crea múltiples redes virtuales para diversos requisitos de servicio y es una tecnología crucial para los sistemas de comunicación futuros y las redes 6G. Esta tecnología facilitará numerosos aspectos de la vida, la sociedad y la industria, satisfaciendo las necesidades de comunicación tanto de humanos como de máquinas inteligentes. Esto se hace posible mediante el uso de tecnologías de softwarización y virtualización, incluyendo redes definidas por software (SDN) y virtualización de funciones de red (NFV), que dotan la flexibilidad y la programabilidad necesarias para el slicing de red. Sin embargo, la implementación de slicing de red en las redes de acceso por radio (RAN) es todo un desafío debido a la complejidad de gestionar las operaciones en el dominio radio. Esta brecha se aborda con el slicing de red zero-touch, un esquema de gestión y orquestación totalmente automatizado, que elimina la necesidad de contratos fijos e intervención manual. El motor de decisiones, un componente principal de esta tecnología, emplea la innovación algorítmica para optimizar la asignación de recursos de la red y manejar los desafíos del slicing de RAN, incluyendo la eficiencia energética, la latencia, la escalabilidad y la confiabilidad. En la asignación de recursos, se utiliza un enfoque de optimización conjunta para equilibrar la energía y la latencia con la calidad del servicio. En concreto, se propone un enfoque Actor-Crítico estocástico para agilizar el procedimiento de aprendizaje y reducir la necesidad de ajustar hiperparámetros en una configuración de slicing de red consciente del consumo energético. Además, se introduce un marco de actor-aprendiz basado en un aprendizaje profundo masivo para abordar los problemas de complejidad y los desafíos de con, Postprint (published version)

Today, billions of smart devices are interconnected via wireless networks, leading to large volumes of video contents circulating through the bandwidth-limited backhaul. This causes network performance to deteriorate. As a mitigation mechanism, caching of highly popular contents to network edges is deployed. We propose a cooperative and demand-aware caching strategy, which is modelled using the Separable Assignment Problem, to maximize the cache hit ratio. This problem is solved with a recursive enumeration method, where dynamic programming is used to fill each edge. The extensive application-level evaluations show that the proposed strategy outperforms existing caching policies., The work of Luis Alonso was supported in part by the Spanish Government under Project PID2021-125799OA-I00., Peer Reviewed, Postprint (author's final draft)

Artificial intelligence (AI)-driven zero-touch massive network slicing is envisioned to be a disruptive technology in beyond 5G (B5G)/6G, where tenancy would be extended to the final consumer in the form of advanced digital use-cases. In this paper, we propose a novel model-free deep reinforcement learning (DRL) framework, called collaborative statistical Actor-Critic (CS-AC) that enables a scalable and farsighted slice performance management in a 6G-like RAN scenario that is built upon mobile edge computing (MEC) and massive multiple-input multiple-output (mMIMO). In this intent, the proposed CS-AC targets the optimization of the latency cost under a long-term statistical service-level agreement (SLA). In particular, we consider the Q-th delay percentile SLA metric and enforce some slice-specific preset constraints on it. Moreover, to implement distributed learners, we propose a developed variant of soft Actor-Critic (SAC) with less hyperparameter sensitivity. Finally, we present numerical results to showcase the gain of the adopted approach on our built OpenAI-based network slicing environment and verify the performance in terms of latency, SLA Q-th percentile, and time efficiency. To the best of our knowledge, this is the first work that studies the feasibility of an AI-driven approach for massive network slicing under statistical SLA., This work has been supported in part by the research projects MonB5G (871780), ZEROTO6G, AGAUR (2017-SGR-891), and PROGRESSUS (876868)., Peer Reviewed, Postprint (author's final draft)

As the demand for Network Function Virtualization accelerates, service providers are expected to advance the way they manage and orchestrate their network services to offer lower latency services to their future users. Modern services require complex data flows between Virtual Network Functions, placed in separate network domains, risking an increase in latency that compromises the offered latency constraints. This shift requires high levels of automation to deal with the scale and load of future networks. In this paper, we formulate the Service Function Chaining (SFC) placement problem and then we tackle it by introducing SCHEMA, a Distributed Reinforcement Learning (RL) algorithm that performs complex SFC orchestration for low latency services. We combine multiple RL agents with a Bidding Mechanism to enable scalability on multi-domain networks. Finally, we use a simulation model to evaluate SCHEMA, and we demonstrate its ability to obtain a 60.54% reduction of average service latency when compared to a centralised RL solution., Peer Reviewed, Postprint (author's final draft)

This paper models and evaluates three FSA-based (Frame Slotted ALOHA) MAC (Medium Access Control) protocols, namely, FSA-ACK (FSA with ACKnowledgements), FSA-FBP (FSA with FeedBack Packets) and DFSA (Dynamic FSA). The protocols are modeled using an AMC (Absorbing Markov Chain), which allows to derive analytic expressions for the average packet delay, as well as the energy consumption of both the network coordinator and the end-devices. The results, based on computer simulations, show that the analytic model is accurate and outline the benefits of DFSA. In terms of delay, DFSA provides a reduction of 17% (FSA-FBP) and 32% (FSA-ACK), whereas in terms of energy consumption DFSA provides savings of 23% (FSA-FBP) and 28% (FSA-ACK) for the coordinator and savings of 50% (FSA-FBP) and 24% (FSA-ACK) for end-devices. Finally, the paper provides insights on how to configure each FSA variant depending on the network parameters, i.e., depending on the number of end-devices, to minimize delay and energy expenditure. This is specially interesting for massive data collection in IoT (Internet-of-Things) scenarios, which typically rely on FSA-based protocols and where the operation has to be optimized to support a large number of devices with stringent energy consumption requirements, Peer Reviewed, Postprint (published version)

In this final degree project, a problem for farmers who collect fruits from the trees is considered. We are going to focus on apples and pears harvest, although the same system could be applicable to other farming activities. The aim of this project is to find an alternative to the inefficient and excessive systems currently used during harvest time, and to set out a solution to the problem by designing a functional prototype. The prototype will be autonomous and will follow farm workers along the fields at a configured distance. It will consist of a specific hardware and software with the Machine Learning application about sensor processing to know the position of the worker constantly. Finally, the production costs will be analyzed, comparing the prototype and the current systems. A discussion about future improvements of this prototype and how it can be applicable to other farming activities is also included in the present work.

Artificial intelligence (AI)-driven zero-touch network slicing (NS) is a new paradigm enabling the automation of resource management and orchestration (MANO) in multi-tenant beyond 5G (B5G) networks. In this paper, we tackle the problem of cloud-RAN (C-RAN) joint slice admission control and resource allocation by first formulating it as a Markov decision process (MDP). We then invoke an advanced continuous deep reinforcement learning (DRL) method called twin delayed deep deterministic policy gradient (TD3) to solve it. In this intent, we introduce a multi-objective approach to make the central unit (CU) learn how to re-configure computing resources autonomously while minimizing latency, energy consumption and virtual network function (VNF) instantiation cost for each slice. Moreover, we build a complete 5G C-RAN network slicing environment using OpenAI Gym toolkit where, thanks to its standardized interface, it can be easily tested with different DRL schemes. Finally, we present extensive experimental results to showcase the gain of TD3 as well as the adopted multi-objective strategy in terms of achieved slice admission success rate, latency, energy saving and CPU utilization., Peer Reviewed, Postprint (published version)

© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., With a view to the expected increased data traffic volume and energy consumption of the fifth generation networks, the use of renewable energy (RE) sources and infrastructure sharing have been embraced as energy and cost-saving technologies. Aiming at reducing cost and grid energy consumption, in the present paper, we study RE exchange (REE) possibilities in late-trend network deployments of energy harvesting (EH) macrocell and small cell base stations (EH-MBSs, EH-SBSs) that use an EH system, an energy storage system, and the smart grid as energy procurement sources. On this basis, we study a two-tier network composed of EH-MBSs that are passively shared among a set of mobile network operators (MNOs), and EH-SBSs that are provided to MNOs by an infrastructure provider (InP). Taking into consideration the infrastructure location and the variety of stakeholders involved in the network deployment, we propose as REE approaches 1) a cooperative RE sharing, based on bankruptcy theory, for the shared EH-MBSs and 2) a non-cooperative, aggregator-assisted RE trading, which uses double auctions to describe the REE acts among the InP provided EH-SBSs managed by different MNOs, after an initial internal REE among the ones managed by a single MNO. Our results display that our proposals outperform baseline approaches, providing a considerable reduction in SG energy utilization and costs, with satisfaction of the participant parties., Peer Reviewed, Postprint (author's final draft)

Pla de Doctorat industrial de la Generalitat de Catalunya, During the recent years, a huge augmentation of the data traffic volume has been noticed, while a further steep increase is expected in the following years. As a result, questions have been raised over the years about the energy consumption needs of the wireless telecommunication networks, their carbon dioxide emissions and their operational expenses. Aiming at meeting the high traffic demands with flat energy consumption and flat incurred expenses, mobile network operators (MNOs) have opted to improve their position (i) by deploying heterogeneous networks (HetNets), which are consisted of macrocell base stations (MBSs) and small cell base stations (SBSs) and (ii) by sharing their infrastructure. However, questions could be raised about the extend to which HetNet densification is of aid. Given that network planning is executed according to high traffic load volumes, BS underutilisation during low-traffic hours cannot be neglected. Similarly, the aggregated energy needs of multiple SBSs equals the ones of an energy hungry MBS, having thus a respectable share of the net energy consumption. In this context, a set of research opportunities have been identified. This thesis provides contribution toward the achievement of a greener and more cost efficient operation of HetNet deployments, where multiple stakeholders develop their activity and where energy support can have the form of various alternate schemes, including renewable energy (RE) sources. Depending on the network energy support, i.e., whether RE sources are used in the network or not, the main body of this thesis is divided in two research directions. The first part of the thesis uses the technology of switching off strategies in order to explore their efficiency in terms of both energy and costs in a HetNet. The HetNet is assumed to be a roaming-based cooperative activity of multiple MNOs that is powered exclusively by grid energy. A switching off and a cost allocation scheme are proposed, using as criteria th, Durante los últimos años, se ha notado un aumento enorme del volumen de tráfico de datos, mientras que se espera un nuevo aumento en los próximos años. Como resultado, se han planteado preguntas sobre las necesidades de consumo de energía de las redes inalámbricas de telecomunicaciones, sus emisiones de dióxido de carbono y sus gastos operativos. Con el objetivo de satisfacer las altas demandas de tráfico con consumo de energía constante y con gastos incurridos constantes, además de utilizar soluciones basadas en la nube, los operadores de redes móviles (MNOs) han optado por mejorar su posición (i) desplegando redes heterogéneas (HetNets), que consisten en estaciones base de macro-células (MBSs) y estaciones base de células pequeñas (SBSs), y (ii) compartiendo su infraestructura. Sin embargo, podrían plantearse preguntas sobre hasta qué punto la densificación de una HetNet es de ayuda. Dado que la planificación de la red se ejecuta de acuerdo con los volúmenes de carga de tráfico más elevados, no se puede descuidar la subutilización de las estaciones base (BS) durante las horas de poco tráfico. De manera similar, las necesidades de energía agregadas de múltiples SBSs son iguales a las de una MBS que consume mucha energía, teniendo así una parte respetable del consumo neto de energía. En este contexto, se ha identificado un conjunto de oportunidades de investigación. Esta tesis contribuye al logro de una operación más ecológica y rentable de las implementaciones de HetNet, donde múltiples partes interesadas desarrollan su actividad y donde el apoyo energético puede tener la forma de varios esquemas alternativos, incluidas las fuentes de energía renovables (RE). Dependiendo del soporte de energía de red, es decir, si las fuentes de RE se usan en la red o no, el cuerpo principal de esta tesis se divide en dos direcciones de investigación. La primera parte de la tesis utiliza la tecnología de las estrategias de apagado con el objetivo de explorar su eficiencia en términ, Postprint (published version)

Currently, air pollution is an obvious reality in the world that poses a risk to public health. Efforts are being made to reduce emissions of polluting gases into the atmosphere and to expand warning services to protect the population from episodes of high pollution. One of the tools used to monitor the problem are the air pollution maps. In Catalonia, these maps are made by interposing the measurements of the permanent stations of the Generalitat distributed throughout the entire territory. The distribution of these stations is not homogeneous and, therefore, the resolution / quality of the map depends very much on the proximity or not to one of these stations. In the near future, these maps also take into account the data provided by Copernicus' European satellite system, which offers a resolution of 7x7 km. If we had more gas measuring equipment, installed in buildings or vehicles with polluting emissions, such as bicycle models, they could be densified at a low cost and deploy a network of sensors that could affect the resolution and reliability of the pollution maps in the most populated areas. In this project we have developed a prototype device for the measurement of air pollutants. The measurement device is lightweight, low cost, with a very low power consumption, includes a microcontroller, different sensors, a positioning system and radio communications. The obtained measurements are sent to a server that are stored in a database allowing to see and analyze the data in graphs and maps of air quality.

There has been much technological advancement in the wireless communic ation in the recent past for the intelligent transportation systems among all Dedicated Short - Range Communication or DSRC or Wireless Access for Vehicular Environment (WAVE) has very important role for the autonomous connected vehicles. It is well known fo r its support for the time sensitive safety applications. Along with safety application, the service to provide nonsafety applications is also becoming very popular, these nonsafety applications may include infotainment, electronic toll tax collection and traffic control to name a few. DSRC protocol consists of WAVE Short Messaging Protocol or WSMP which aims to provide real time safety application and it is also able to support some nonsafety related applications. In our dissertation we aim to evaluate the performance of IEEE 802.11p standard for both safety and nonsafety messages. Our sce norio for master thseis consists of fleet of vehicles that are moving with constant speed and in the same direction forming the platoon pattern. The distance between ever y two vehicles is set to be constant and it is kept 200 meters, similarly every vehicle is moving with constant speed of 20 m/sec. To develop the scenorio for Basic Safety Messages, each vehicle is able to generate BSM messages periodically and it fixed pa yload size of 200 bytes and data rate of 6 Mbits/sec. For the nonsafety messages we also compare the perfor m ance of existing protocols such as optimized link state routing OLSR protocol and Ad - hoc O n - demand Routing AODV protocol, the packet size is kept 25 6 bytes at 8 kbps. We have used the metrics such as throughput, packet delivery ratio , packet loss ratio and end to end delay for evaluaing the performance of as optimized link state routing OLSR protocol and Ad - hoc On - demand Routing AODV protocols Our si mulation results conducted in Network Simulator NS - 3 show that WSMP protocol have adequate level of packet delivery r

©2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., Emerging 5G communication paradigms, such as machine-type communication, have triggered an explosion in ad-hoc applications that require connectivity among the nodes of wireless networks. Ensuring a reliable network operation under fading conditions is not straightforward, as the transmission schemes and the network topology, i.e., uniform or clustered deployments, affect the performance and should be taken into account. Moreover, as the number of nodes increases, exploiting natural energy sources and wireless energy harvesting (WEH) could be the key to the elimination of maintenance costs while also boosting immensely the network lifetime. In this way, zero-energy wireless-powered sensor networks (WPSNs) could be achieved, if all components are powered by green sources. Hence, designing accurate mathematical models that capture the network behavior under these circumstances is necessary to provide a deeper comprehension of such networks. In this paper, we provide an analytical model for the connectivity in a large-scale zero-energy clustered WPSN under two common transmission schemes, namely, unicast and broadcast. The sensors are WEH-enabled, while the network components are solar-powered and employ a novel energy allocation algorithm. In our results, we evaluate the tradeoffs among the various scenarios via extensive simulations and identify the conditions that yield a fully connected zero-energy WPSN., Peer Reviewed, Postprint (author's final draft)

Visible Light Communications (VLC) is a technology that has emerged in recent years proposing some improvements over traditional radio communications. The objective of this project is to evaluate the bit error rate of different modulations schemes and the requirements of optical communications are described. It is discussed which of them is better to set VLC transmissions. For this, the work has been divided into three sections. The first section describes the communication systems in visible light, as well as the modulations schemes that could be used, more specifically, those that are based on OFDM. In the second section, the MATLAB simulations performed are detailed, representing the bit error rate graph of each of the modulations, varying an added noise. In the third section, the simulations are moved into a real case. For this, two computers and two USRPs modules are used. One of the PC will act as a transmitter and the other as a receiver. The USRPs work as analog-digital/digital-analog converters and are connected to each other by a cable that introduces attenuation. The objective of this configuration is to estimate the bit error rate, varying the noise. Finally, the system is evaluated by replacing the cable that used to connect both USRPs with a LED and a photodetector. In this way, a real practical case of a system based on visible light communications is shown, its performance is studied, and the conclusions are presented.

Nowadays, fiber optic companies are focused on deployments of FTTH in more than 200 households and with access from a nearby fiber optic point from which to begin deployment in the urban core. For this reason, populations with low housing density and a point of access to the distant fiber network will be the last to have access to high speed (FTTH). The objective of this final degree work (F.D.W) is to study and design the populations that FTTH operators leave in the end because they are less profitable. The place chosen for the study has been four populations of Aran Valley, where there are a large number of small populations and with a difficult access to get the fiber optic. The villages are: Vilac, Mont, Montcorbau and Betlan. The first step will be to rent a dark fiber that is closest to study populations, which in this case will be carried out by the telecommunications operator Movistar, which has the service FTTH in Vielha (Aran Valley). In the closest manhole to the phone station we will be given the two fibers to carry out our deployment. At this point we have two possibilities, the first is to bring the fiber cable to the four municipalities by installing a pole where we will not have a pipe, while in the second option we will carry the fiber cable piped to the point where we will locate an antenna with some Radio links in each of the populations The antennas will be located in areas where we have a direct view between the two devices. In addition, the antennas will be located within the populations in the best place, that is, high points where you have a vision with the whole population, where you can reuse these same antennas because 5G panels can be placed in the next years. Finally, we will design the populations to the optical terminal boxes (CTO's). Likewise, derived from all the phases of the project, we will make a budget with which we will compare what it would be supposed to do with the deployment of FTTH in small populations and whether it will

©2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., Macrocells are expected to be densely overlaid by small cells (SCs) to meet increasing capacity demands. Due to their dense deployment, some SCs will not be connected directly to the core network, and thus, they may forward their traffic to the neighboring SCs until they reach it, thereby forming a multihop backhaul (BH) network. This is a promising solution, since the expected short length of BH links enables the use of millimeter-wave (mmWave) frequencies to provide high-capacity BH. In this context, user association becomes challenging due to the multihop BH architecture, and therefore, new optimal solutions should be developed. Thus, in this paper, we study the user association problem aiming at the joint maximization of network energy efficiency (EE) and spectrum efficiency (SE), without compromising the user quality of service (QoS). The problem is formulated as an e-constraint problem, which considers the transmit energy consumption both in the access network, i.e., the links between the users and their serving cells, and the BH links. The optimal Pareto-front solutions of the problem are analytically derived for different BH technologies, and insights are gained into the EE and SE tradeoff. The proposed optimal solutions, despite their high complexity, can be used as a benchmark for the performance evaluation of user association algorithms. We also propose a heuristic algorithm, which is compared with reference solutions under different traffic scenarios and BH technologies. Our results motivate the use of mmWave BH, whereas the proposed algorithm achieves near-optimal performance., Peer Reviewed, Postprint (author's final draft)

This is the peer reviewed version of the following article: Vazquez-Gallego F, Tuset-Peiró P, Alonso L, Alonso-Zarate J. Combining distributed queuing with energy harvesting to enable perpetual distributed data collection applications. Trans Emerging Tel Tech. 2017;e3195 , which has been published in final form at https://doi.org/10.1002/ett.3195. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving., This paper presents, models, and evaluates energy harvesting–aware distributed queuing (EH-DQ), a novel medium access control protocol that combines distributed queuing with energy harvesting (EH) to address data collection applications in industrial scenarios using long-range and low-power wireless communication technologies. We model the medium access control protocol operation using a Markov chain and evaluate its ability to successfully transmit data without depleting the energy stored at the end devices. In particular, we compare the performance and energy consumption of EH-DQ with that of time-division multiple access (TDMA), which provides an upper limit in data delivery, and EH-aware reservation dynamic frame slotted ALOHA, which is an improved variation of frame slotted ALOHA. To evaluate the performance of these protocols, we use 2 performance metrics: delivery ratio and time efficiency. Delivery ratio measures the ability to successfully transmit data without depleting the energy reserves, whereas time efficiency measures the amount of data that can be transmitted in a certain amount of time. Results show that EH-DQ and TDMA perform close to the optimum in data delivery and outperform EH-aware reservation dynamic frame slotted ALOHA in data delivery and time efficiency. Compared to TDMA, the time efficiency of EH-DQ is insensitive to the amount of harvested energy, making it more suitable for energy-constrained applications. Moreover, compared to TDMA, EH-DQ does not require updated network information to maintain a collision-free schedule, making it suitable for very dynamic networks., Peer Reviewed, Postprint (author's final draft)

The present paper studies fair sharing possibilities of stored renewable energy (RE) in densely populated areas among multiple mobile network operators (MNOs). The main objective is to enable MNOs, who already share their infrastructure in terms of a green network operation, to further reduce their power consumption by fairly sharing (i) the solar power harvested during daylight and (ii) the harvested energy that is stored in storage devices, e.g. batteries, during night hours. To this end, a bankruptcy game is designed so as to capture the energy sharing interactions among MNOs. Taking into consideration the energy deficits of each MNO for a studied period of time, Shapley Value (SV) is employed to fairly determine the amounts of energy to be allocated to each MNO. Focusing on night hours, it is shown that the proposed scheme provides all cooperative MNOs with long store-energy-based network operation during night in comparison to baseline schemes. Moreover, we display that the proposed scheme outperforms its counterparts in terms of needed grid support and allocation fairness among the cooperative MNOs for different MNO traffic patterns and volumes., Peer Reviewed, Postprint (published version)

©2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., The explosive data traffic demand in the context of the 5G revolution has stressed the need for network capacity increase. As the network densification has almost reached its limits, mobile network operators are motivated to share their network infrastructure and the available resources through dynamic spectrum management. Although some initial efforts have been made in this direction by concluding sharing agreements at a coarse granularity (i.e., months or years), the 5G developments require fine timescale agreements, mainly enabled by network slicing. In this article, taking into account the radical changes foreseen for next generation networks, we provide a thorough discussion of the challenges that network slicing brings in the different network parts, while introducing a new entity capable of managing the end-to-end slicing in a coherent manner. In addition, according to the paradigm shift of operators sharing their resources in a common centralized pool, we design a cooperative game to study the potential cooperation aspects among the participants. The experimental results highlight the performance and financial gains achievable by operators through multi-tenant slicing, providing them with the necessary incentives for network upgrade toward 5G., Peer Reviewed, Postprint (author's final draft)

©2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., The anticipated explosion in the total data traffic load will impose to mobile network operators (MNOs) the necessity to densify their networks to provide coverage. At the same time, since MNOs plan their networks according to their high-peak traffic load, base station (BS) underutilization during the low traffic hours raises the issue of unnecessary power consumption and excessive cost. In this paper, we plan to study the energy and cost efficiency of a heterogeneous network (HetNet) that is a cooperation result of many MNOs. Each MNO is owner of a HetNet, composed of eNodeBs and small cells and they cooperate by sharing their infrastructure and by switching off a part of it. BS type and traffic load constitute switching off criteria and a roaming-cost-based user association scheme is used to roam traffic to neighboring BSs. We assess the cost alterations created by the possible MNO coalitions and we propose a bankruptcy game to allocate the obtained cost to the cooperative MNOs and to motivate them thus to maintain their sharing agreement instead of following a non-cooperative tactic. The bankruptcy game uses Shapley Value to portray each MNO's contribution to cost savings. The MNOs’ satisfaction from their payoffs (i.e., the allocated cost) and the overall fairness of the method are evaluated. According to the extracted results, the proposed switching off scheme achieves significant improvement of energy efficiency for the studied network, while the proposed bankruptcy game achieves a balanced and satisfactory cost allocation for different MNO traffic loads., Peer Reviewed, Postprint (author's final draft)

©2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., In this paper, we consider a wireless machine-to-machine network composed of end-devices with energy harvesters that periodically transmit data to a gateway. While energy harvesting allows for perpetual operation, the uncertain amount of harvested energy may not guarantee fully continuous operation due to temporary energy shortages. This fact needs to be addressed at the medium access control layer. We thus investigate the performance of an energy harvesting-aware contention tree-based access (EH-CTA) protocol, which uses a tree-splitting algorithm to resolve collisions and takes energy availability into account. We derive a theoretical model to compute the probability of delivery and the time efficiency. In addition, we conduct a performance comparison of EH-CTA using an EH-aware dynamic frame slotted-ALOHA (EH-DFSA) as a benchmark. We determine the parameters that maximize performance and analyze how it is influenced by the amount of harvested energy and the number of end-devices. Results reveal the superior performance of EH-CTA over EH-DFSA. While EH-DFSA requires an estimate of the number of contending end-devices per frame to adapt the frame length, EH-CTA uses short and fixed frame lengths, which enables scalability and facilitates synchronization as the network density increases., Peer Reviewed, Postprint (author's final draft)

©2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., In this paper we demonstrate an analytical model for computing the end to end packet delay of a converged Optical/Wireless 60GHz Radio-over-Fiber (RoF) network operating under the Medium-Transparent MAC (MT-MAC) protocol. For the calculation of the cycle times this model takes into account contention both at the optical and the wireless layer, that effectively enables the MT-MAC to provide a seamless and dynamic capacity allocation over both optical and wireless transmission media. This new analytical model enables us to conduct an extensive delay performance analysis of the various performance aspects of hybrid RoF networks operating under the fixed service paradigm, such as various optical capacity availability scenarios, varying load conditions, optical network ranges, transmission window lengths and data packet sizes. The derived theoretical results are found to be in excellent agreement with the respective simulation-based findings, providing sub millisecond latency values for a plethora of network conditions, confirming that the Medium Transparent MAC protocols can effectively be incorporated into the upcoming mm-wave 5G era., Peer Reviewed, Postprint (author's final draft)

In order to address the explosive demand for high-capacity and omnipresent wireless access, modern cell-based wireless networks are slowly adopting two major solution roadmaps. The first is the employment of small-cell formations in order to increase the overall spectral efficiency, whereas the second is the employment of higher frequency bands, such as the mm-wave 60GHz band, that offers vast amounts of bandwidth. Depending on the specific application, the above solutions inevitably require the installation and operational management of large amounts of Base Stations (BSs) or Access Points (APs), which ultimately diminishes the overall cost-effectiveness of the architecture. In order to reduce the system cost, Radio over Fiber (RoF) technology has been put forward as an ideal candidate solution, due to the fact that it provides functionally simple antenna units, often termed as Remote Antenna Units (RAUs) that are interconnected to a central managing entity, termed as the Central Office (CO), via an optical fiber. Although extensive research efforts have been dedicated to the development of the physical layer aspects regarding RoF technologies, such as CO/RAU physical layer design and radio signal transport techniques over fiber, very limited efforts have con-centrated on upper layer and resource management issues. In this dissertation, we are concerned with access control and resource management of RoF-based mm-wave network architectures targeting the exploitation of the dual medium and its centralized control properties in order to perform optimal optical/wireless/time resource allocation. In this dissertation, we propose a Medium-Transparent MAC (MT-MAC) protocol that concurrently administers the optical and wireless resources of a 60GHz RoF based network, seamlessly connecting the CO to the wireless terminals through minimal RAU intervention. In this way, the MT-MAC protocol forms extended reach 60GHz WLAN networks offering connectivity amongst wireless devices, A fin de atender la demanda explosiva de alta capacidad y acceso inalámbrico omnipresente, las redes inalámbricas basadas en celdas están poco a poco adoptando dos principales guías de solución. La primera es el empleo de formaciones de celdas pequeñas con el fin de aumentar la eficiencia espectral global, mientras que la segunda es el empleo de bandas de frecuencia superior, como la banda de 60GHz, la cual ofrece una gran cantidad de ancho de banda. Dependiendo de la aplicación en específico, las soluciones anteriores inevitable-mente requieren de una instalación y una gestión operativa de grandes cantidades de Estaciones Base o Puntos de Acceso, que en última instancia disminuye la rentabilidad de la arquitectura. Para reducir el coste, la tecnología radioeléctrica por fibra (RoF) se presenta como una solución ideal debido al hecho de que proporciona unidades de antenas de sim-ple funcionamiento, a menudo denominadas Unidades de Antenas Remotas (RAUs), las cuales están interconectadas a una entidad central de gestión, denominada Oficina Central (CO), a través de la fibra óptica. A pesar de que se han dedicado muchos esfuerzos de investigación al desarrollo de varios aspectos de las capas física con respecto a las tecnologías RoF, muy pocos esfuerzos se han concentrado en la capa superior y cuestiones de gestión de recursos. En esta tesis, nos enfocando en el control de acceso y gestión de recursos de arquitecturas RoF y comunicaciones milimétricas, con el fin de aprovechar y explotar el medio dual y las propiedades para realizar una óptima asignación de los recursos ópticos, inalámbricos y temporales. Nosotros proponemos un protocolo Transparente al Medio MAC (MT-MAC) que simultáneamente administre los recursos ópticos e inalámbricos de una red RoF a 60GHz, conectando a la perfección el CO a los terminales inalámbricos a través de una mínima intervención RAU. El protocolo MT-MAC forma unas redes WLAN 60GHz de alcance extendido, ofreciendo así conectividad entre lo, Postprint (published version)

©2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., In spite of the significant advancements in wireless connectivity, the static form of the network infrastructure cannot guarantee an uninterrupted operation of the ever-growing wireless consumer electronics in emergency situations such as natural disasters. In such occasions, employing flexible aerial nodes can tackle this issue by recovering the communication rapidly, when the need for connectivity is of utmost importance. In this paper, we study the use of aerial nodes for communication recovery after a communication breakdown. We provide an analytical model of the recovery probability that demonstrates the capabilities of such networks. In the performance evaluation, we show the effects of the altitude and the distance between the aerial nodes on the recovery probability and verify them with simulations. Moreover, we introduce our testbed and preliminary experimental work that shows promising results for aerial networks. Finally, we discuss useful insights for the network design and present some open issues that exist in this field., Peer Reviewed, Postprint (author's final draft)

Premi Extraordinari de Doctorat, promoció 2016-2017. Àmbit d’Enginyeria de les TIC, Undeniably, the progress in wireless networks during the last two decades is extraordinary. However, the ever-increasing upward trend in the numbers of wireless devices that will overwhelm every field of our everyday life, e.g., building automation, traffic management, health-care, etc., will introduce several issues in terms of communication and energy provision that need to be handled in advance. Regarding the communication issues, it is imperative to ensure the correct operation of the vast collection of nodes, especially for life-critical applications. Two well-known metrics that can characterize sufficiently the network reliability are the coverage and the connectivity probability that are derived by taking into account the network topology, the channel conditions between every transmitter-receiver pair, and the interference from other nodes. Nevertheless, considering all those factors is not straightforward. Lately, stochastic geometry has come into prominence, which is a mathematical tool to study the average network performance over many spatial realizations, while considering all aforementioned factors. Moreover, the other crucial issue for the large-scale dense network deployments of the future is their energy supply. Traditional battery charging or swapping for the wireless devices is both inconvenient and harms the environment, especially if we take into account the enormous numbers of nodes. Therefore, novel solutions have to be found using renewable energy sources to zero down the significant electricity consumption. Wireless energy harvesting is a convenient and environmentally-friendly approach to prolong the lifetime of networks by harvesting the energy from radio-frequency (RF) signals and converting it to direct current electricity through specialized hardware. The RF energy could be harvested from signals generated in the same or other networks. However, if the amount of harvested energy is not sufficient, solar-powered dedicated transmitters cou, Innegablemente, el progreso en las redes inalámbricas durante las últimas dos décadas es extraordinario. Sin embargo, la creciente tendencia al alza en el número de dispositivos inalámbricos que abarcarán todos los ámbitos de nuestra vida cotidiana, como la automatización de edificios, la gestión del tráfico, la atención sanitaria, etc., introducirá varias cuestiones en términos de comunicación y suministro de energía que se debe tener en cuenta con antelación. Respecto a los problemas de comunicación, es imprescindible asegurar el correcto funcionamiento de la vasta colección de nodos, especialmente para las aplicaciones vitales. Dos métricas bien conocidas que pueden caracterizar suficientemente la fiabilidad de la red son la probabilidad de cobertura y la de conectividad, que se derivan teniendo en cuenta la topología de la red, las condiciones del canal entre cada par transmisor-receptor y la interferencia de otros nodos. Sin embargo, considerar todos esos factores no es sencillo. Últimamente, la geometría estocástica ha llegado a la prominencia como un metodo de análisis, que es una herramienta matemática para estudiar el rendimiento promedio de la red sobre muchas realizaciones espaciales, teniendo en cuenta todos los factores mencionados. Además, la otra cuestión crucial para los despliegues de alta densidad de las redes futuras es su suministro de energía. La carga o el intercambio de baterías para los dispositivos inalámbricos es inconveniente y daña el medio ambiente, especialmente si tenemos en cuenta el enorme número de nodos utilizados. Por lo tanto, se deben encontrar nuevas soluciones utilizando fuentes de energía renovables para reducir el consumo de electricidad. La recolección de energía inalámbrica es un método conveniente y respetuoso con el medio ambiente para prolongar la vida útil de las redes recolectando la energía de las señales de radiofrecuencia (RF) y convirtiéndola en electricidad de corriente continua mediante un hardware especializado, Award-winning, Postprint (published version)

Facing the increasing energy demands associated with the perspective of fifth generation (5G) wireless networks, the Mobile Network Operators (MNOs) are motivated to gradually convert their traditional Radio Access Network (RAN) infrastructure to more flexible and power efficient centralized architectures, i.e., Cloud-RAN (C-RAN). Apart from their promising benefits in terms of management and network optimization, these new architectures further enable the sharing of spectrum and network elements, such as the Remote Radio Heads (RRHs) and the Baseband Units (BBUs), among multiple operators. In this paper, we introduce a novel scheme based on coalitional game theory to identify the potential room for cooperation among different MNOs that provide service to the same area. The proposed scheme sets the rules for profitable collaboration and identifies the core formation conditions (i.e., pricing) for various scenarios with different market and spectrum shares among three operators. Our results show that i) cooperation among subcoalitions of MNOs is always beneficial, yielding both higher revenues and enhanced Quality of Service (QoS) for the end users, and ii) the cooperation of all operators (grand coalition) is profitable for given user pricing in different scenarios., Peer Reviewed, Postprint (published version)

As wearables provide new health-related functionalities, they can be employed in hospitals to monitor patients and notify the medical personnel regarding their status. However, in order to be approved by the medical community, wearables need to have reliable communication and high lifetime. In such scenarios, it is important to know the probability of correct notification which is affected mainly by the deployment of the wireless wearables and their energy supply. Typically, rooms in hospitals host multiple people and, thus, a clustered communication model should be adopted for more trustworthy results. Moreover, by employing wireless charging, it is possible to provide an uninterrupted operation with high reliability. Therefore, in this paper, we study the aforementioned probability in a clustered network while the wearable devices are wirelessly charged. We provide an analytical model for the wearables' ability to inform quickly the medical personnel and discuss different trade-offs via extensive simulations., Peer Reviewed, Postprint (published version)

This final grade project contains information related to the FTTH network (fiber to the home) by developing the distribution network of an area. The aim of this project is to show in detail how the designs of the optical fiber distribution network are designed in different populations, observing the limitations, looking for ways to overcome them and be able to serve all the clients of the area. For the realization of this work, I have chosen an area of Girona more specifically in the municipality of Palafrugell since it currently has no optical fiber and has good characteristics to show in detail the distribution of a fiber optic network. The preparation of this work is carried out taking into account that we are a new telephone operator, establishing a first chapter that explains in detail the design criteria trying to cover all the possible diferent situations to finish the project designing it and explaining why all things are done. The network described in this work will allow end users to obtain high performance coverage (100 Mbps speed is guaranteed in all households with fiber coverage) and optimization of the infrastructure of the new network. We will mark a balance between high performance, adequate sizing and adequate development guarantees also triying the reduction of maintenance

Premi extraordinari doctorat UPC curs 2015-2016, àmbit Enginyeria de les TIC, The rapid expansion of mobile services and the emerging demand for multimedia applications have led to an impressive traffic growth. To this end, Mobile Network Operators (MNOs) seek to extend their infrastructure by installing more Base Stations (BSs), in an effort to increase the network capacity and meet the pressing traffic demands. Furthermore, to fulfill the escalated demands, Heterogeneous Networks (HetNets), which consist of Small Cells (SCs) and the traditional BSs, constitute the new trend of next generation networks. The deployed infrastructure implies a rise in the Capital Expenditures and has a direct impact on the network energy consumption, thus resulting in higher Operational Expenditures. Hence, the investigation of energy efficient solutions will bring down the energy consumption and the network cost. Since the BS is the most power hungry component, the research community has shifted towards the investigation of BS deactivation schemes. These schemes propose that part of the infrastructure can be temporarily switched off, when the traffic is low, while the active BSs extend their coverage to serve the network. Based on a comprehensive review of the state-of-the-art, a set of research opportunities were identified. This thesis provides contributions to the field of BS switching off strategies for wireless macro BSs networks and HetNets of single and multiple MNOs by proposing mechanisms that enhance different aspects of the network performance. The BSs deactivation, the innovative trend of infrastructure sharing and the financially driven collaboration among the involved parties of the current and future networks promise significant improvements in terms of energy and cost savings. The main thesis contributions are divided into three parts, described next. The first part of the thesis introduces innovative BS switching off approaches in single-operator environments, where only macro BSs are deployed. The proposed strategies exploit the inherit chara, La rápida expansión de los servicios móviles y de la demanda emergente de aplicaciones multimedia han dado lugar a un impresionante crecimiento del tráfico. Operadores de redes móviles (MNOs) tratará de extender su infraestructura mediante la instalación de más estaciones base (BSs), en un esfuerzo por aumentar la capacidad de la red y satisfacer las apremiantes demandas de tráfico. Además, para cumplir con las exigencias escalada, redes heterogéneas (HetNets), constituyen la nueva tendencia de las redes de próxima generación. La infraestructura implica un aumento en los gastos de capital y tiene un impacto directo en el consumo de energía a la red, lo que resulta en un aumento de los gastos operacionales. La investigación de soluciones de eficiencia energética hará bajar el consumo de energía y el coste de la red. La comunidad científica se ha desplazado hacia la investigación de los sistemas de desactivación de BSs. Estos esquemas proponen que parte de la infraestructura se puede cdesectivarse, cuando el tráfico es bajo, mientras que los BSs activas extender su cobertura al servicio de la red. Esta tesis ofrece contribuciones al campo de la BSs desconexión para las redes y HetNets con uno o multiples MNOs, proponiendo mecanismos que mejoran diferentes aspectos del rendimiento de la red. La desactivación de BS,s la tendencia innovadora de compartir infraestructura y la colaboración impulsada financieramente entre las partes implicadas de las redes actuales y futuras prometen mejoras significativas en términos de ahorro energético y económico. Las principales contribuciones de tesis se dividen en tres partes, que se describen a continuación. La primera parte de la tesis introduce innovadora apagar enfoques en entornos de un solo operador, donde se despliegan sólo macro BSs. Las estrategias propuestas explotan las características de tráfico (por ejemplo, la distribución de los usuarios, el volumen de tráfico, etc.) y las características distintivas de las redes (por, Award-winning, Postprint (published version)

© 2016 [2016 Optical Society of America.]. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited., We present a study concerning the network planning of 60 GHz gigabit wireless local area networks (WLANs) over existing passive optical network (PON) infrastructures. Two fiber-wireless configurations for gigabit WLAN network formations are investigated: i) the Radio & Fiber (R&F) approach that considers several 802.11ad access points connected to conventional gigabit passive optical network (GPON) optical network units, henceforth termed as the GPON-plus-802.11ad approach; and ii) the Radio-over-Fiber (RoF) paradigm that employs several remote access units operating under the medium-transparent MAC (MT-MAC) protocol, hence termed as the MT-MA-Cover-PON approach. Simulation-based throughput and delay results are obtained for both network scenarios, revealing the dependence of the 60 GHz enterprise network performance on several network-planning parameters such as load, traffic shape, number of optical wavelengths in the backhaul, and optical backhaul fiber length, highlighting in each case the prevailing architecture. Based on the respective findings we also study a hybrid multitier architecture, termed the GPON-plus-MT-MAC approach, that fuses the abilities of both the RoF and R&F architectures in order to optimally combine their properties and set a framework for next-generation 60 Ghz fiber-wireless networks., Peer Reviewed, Postprint (author's final draft)

©2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., The introduction of fourth-generation wireless technologies has fueled the rapid development of cellular networks, significantly increasing the energy consumption and the expenditures of mobile network operators (MNOs). In addition, network underutilization during low-traffic periods (e.g., night zone) has motivated a new business model, namely, infrastructure sharing, which allows the MNOs to have their traffic served by other MNOs in the same geographic area, thus enabling them to switch off part of their network. In this paper, we propose a novel infrastructure-sharing algorithm for multioperator environments, which enables the deactivation of underutilized base stations during low-traffic periods. Motivated by the conflicting interests of the MNOs and the necessity for effective solutions, we introduce a game-theoretic framework that enables the MNOs to individually estimate the switching-off probabilities that reduce their expected financial cost. Our approach reaches dominant strategy equilibrium, which is the strategy that minimizes the cost of each player. Finally, we provide extensive analytical and experimental results to estimate the potential energy and cost savings that can be achieved in multioperator environments, incentivizing the MNOs to apply the proposed scheme., Peer Reviewed, Postprint (author's final draft)

Mobile data offloading has been proposed as a solution for the network congestion problem that is continuously aggravating due to the increase in mobile data demand. However, the majority of the state-of-the-art is focused on the downlink offloading, while the change of mobile user habits, like mobile content creation and uploading, makes uplink offloading a rising issue. In this work we focus on the uplink offloading using IP Flow Mobility (IFOM). IFOM allows a LTE mobile User Equipment (UE) to maintain two concurrent data streams, one through LTE and the other through WiFi access technology, that presents uplink limitations due to the inherent fairness design of IEEE 802.11 DCF by employing the CSMA/CA scheme with a binary exponential backoff algorithm. In this paper, we propose a weighted proportionally fair bandwidth allocation algorithm for the data volume that is being offloaded through WiFi, in conjunction with a pricing-based rate allocation for the rest of the data volume needs of the UEs that are transmitted through the LTE uplink. We aim to improve the energy efficiency of the UEs and to increase the offloaded data volume under the concurrent use of access technologies that IFOM allows. In the weighted proportionally fair WiFi bandwidth allocation, we consider both the different upload data needs of the UEs, along with their LTE spectrum efficiency and propose an access mechanism that improves the use of WiFi access in uplink offloading. In the LTE part, we propose a two-stage pricing-based rate allocation under both linear and exponential pricing approaches, aiming to satisfy all offloading UEs regarding their LTE uplink access. We theoretically analyse the proposed algorithms and evaluate their performance through simulations. We compare their performance with the 802.11 DCF access scheme and with a state-of-the-art access algorithm under different number of offloading UEs and for both linear and exponential pricing-based rate allocation for the LTE upl, Peer Reviewed, Preprint

The Energy Harvesting-aware Contention Treebased Access (EH-CTA) protocol is presented in this paper as a novel Medium Access Control (MAC) protocol for wireless Machine-to-Machine (M2M) networks where enddevices are equipped with energy harvesters. The protocol is theoretically modeled to analyze its performance. A performance comparison with an EH-aware Dynamic Frame Slotted-ALOHA (EH-DFSA) shows its superior performance. While EH-DFSA requires an estimation of the number of contenders per frame in order to dynamically adjust the frame length, EH-CTA uses short and fixed frame lengths. This ensures scalability and facilitates synchronization in highly dense M2M networks., Peer Reviewed, Postprint (published version)

Contemporary technologies as implemented in the field of healthcare have provided the everyday clinical practice with a plethora of tools to be used in various settings. In this field, distributed and networked embedded systems, such as Wireless Sensor Networks (WSNs), are the most promising technology to achieve continuous monitoring of aged people for their own safety, without affecting their daily activities. WSN4QoL is a Marie Curie project involving academic and industrial partners from three EU countries, which aims to show how new WSNsbased technologies suit the specific requirements of pervasive healthcare applications. In particular, in this paper, the WSN4QoL's system architecture is presented as designed to exploit the Network Coding (NC) mechanisms to achieve energy efficiency in the wireless communications and distributed positioning solutions to locate patients in indoor home environments. The system has been validated through experimental activities using commercial off the shelf (COTS) WSN testbeds and medical devices prototypes offered by a commercial partner. Results demonstrate that NC helps in achieving substantial gains in terms of energy efficiency as compared to traditional relay mechanisms, while the proposed positioning solution is able to locate people in indoor environments at a sub-room accuracy level, without requiring any extra dedicated hardware., Peer Reviewed, Postprint (published version)

The Energy Harvesting-aware Distributed Queuing access protocol (EH-DQ) is presented in this paper as a novel Medium Access Control protocol for wireless Machineto-Machine networks with energy harvesting capabilities. EHDQ is theoretically modeled to analyze its performance. A performance comparison with a Time Division Multiple Access (TDMA) and an EH-aware Reservation Dynamic Frame SlottedALOHA (EH-RDFSA) shows its superior performance. While TDMA requires updated network information to maintain a collision-free schedule and EH-RDFSA requires to estimate the number of contenders per frame to dynamically adjust the frame length, EH-DQ uses short and fixed frame lengths and does not require knowledge of the network topology or the number of end-devices in advance., Peer Reviewed, Postprint (published version)

Current mobile communication infrastructure may fail in cases where low coverage areas suddenly become overcrowded by mobile devices or in natural disasters. In this paper, we propose the use of flexible aerial relay (FAR) nodes for communication recovery and device-to-device (D2D) relaying, as an energy efficient and cost-effective way to resolve these issues rapidly. We discuss the technical characteristics of the system and determine analytically the range of the FAR nodes., Peer Reviewed, Postprint (published version)

Due to the dense small cell deployment to cope with the increased data traffic of fifth generation (5G) networks, the direct backhaul (BH) connection of all small cells to the core network becomes challenging. To that end, millimeter wave (mmWave) technology is a promising solution for cost-efficient high capacity small cell BH links. However, due to the severe signal attenuation at high frequencies, mmWave can provide good coverage only for short distances, thus favoring a multihop 5G BH architecture. In this context, where BH is expected to play a key role, traditional problems such as user association that impact both the network and user performance call for BH-aware strategies. Hence, in this paper, we study the user association problem aiming at the joint energy and spectrum efficiency maximization of the network, without compromising the user quality of service. The problem is formulated as a generalized assignment problem, which considers the capacity and energy consumption both in the access network and BH links. Provided that the considered problem is shown to be NP-hard, we employ optimization techniques to obtain an upper bound on system performance. We also propose a low complexity algorithm, which is shown to outperform the state-of-the-art while achieving near-optimal performance., Peer Reviewed, Postprint (published version)

©2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., In this letter we focus on the uplink offloading with IP Flow Mobility (IFOM). With IFOM a User Equipment (UE) is able to maintain concurrently two data streams, one through LTE and the other through WiFi. We consider the existence of malicious UEs that aim to exploit the WiFi bandwidth against their truthful peers, in order to upload less data through the energy demanding LTE uplink and a reputation based method is proposed to combat the selfish operation. The WiFi bandwidth is allocated based on weighted proportional fairness and the LTE rate is defined through an exponential pricing algorithm. We theoretically analyse our approach and evaluate the performance of the malicious and the truthful UEs in terms of energy efficiency and throughput, through simulations. We show that while the malicious UEs present better energy efficiency before being detected, their performance is significantly degraded with the proposed reaction method., Peer Reviewed, Postprint (author's final draft)

The emerging traffic demand has triggered an impressive deployment of network infrastructure, including macro Base Stations (BSs) and Small Cells (SCs), leading to increased energy consumption and expenditures. However, the network underutilization during low traffic periods (e.g., night zone) enables the Mobile Network Operators (MNOs) to save energy by having their traffic served by third-party SCs, thus being able to switch off their BSs. In this paper, we propose a novel market approach to foster the opportunistic utilization of unexploited SCs capacity, where the MNOs lease the resources of third-party SCs and deactivate their BSs. Motivated by the conflicting interests of the MNOs and the restricted capacity of the SCs that is not adequate to carry the whole traffic in multioperator scenarios, we introduce a combinatorial auction framework, which includes: i) a bidding strategy, ii) a resource allocation scheme, and iii) a pricing rule. We propose a multiobjective framework to provide an energy efficient solution for the resource allocation problem and we provide extensive analytical and experimental results to estimate the potential energy savings., Peer Reviewed, Postprint (published version)