[pt] A ascenção dos computadores e da banda-larga móvel e fixa são fatores importantes nas mudanças observadas no mercado de trabalho dos países ricos. Conforme o mundo tecnológico rapidamente evolui e cada vez mais rápida conectividade surge, há pouca evidência dos impactos das atuais tecnologias nos países em desenvolvimento. O Brasil, em particular, durante a última década, observou uma notória expansão do acesso à internet móvel. Nesta dissertação, explora-se o rápido avanço da cobertura de 4G para estimar os efeitos causais de internet móvel rápida para mercados locais de trabalho formal no Brasil. Como as tecnologias de 4G não são instaladas randomicamente, compromissos de abrangência, presentes nos contratos entre operadores nacionais da banda de 4G e a agência nacional de telecomunicações (ANATEL), servem como variável instrumental para presença de internet. O crescimento médio observado na amostra de número de operadores presente em cada mercado local é responsável por uma redução de 8 porcento nos contratos formais de trabalho (40 porcento da variação no período). Esta redução é causada por (i) redução de rotatividade e por (ii) efeitos de desemprego. Consistentes com a hipótese de rotineirização, o 4G reduz a demanda de trabalho para tarefas rotineiras e manuais. Com isso, há um aumento da proporção de trabalhadores com ensino superior e em ocupações que exigem maior qualificação. Os efeitos são concentrados no extremo da distribuição dos setores em termos de uso de tecnologias, mas não houve efeitos na composição das indústrias. Identifica-se evidência sugestiva de que banda-larga móvel está associada à polarização nos empregos. / [en] The rise of computerization and fixed and mobile broadband has been an important factor for changes in the labor market of rich countries. However, as the world of tech rapidly evolves and even faster mobile internet emerges, there is still little evidence about the impact of current mobile technologies in developing countries. Brazil, in particular, during the last decade, has seen a remarkable increase in mobile internet access. In this dissertation, I explore this rapid expansion of 4G coverage to estimate the causal effects of fast mobile internet in formal local labor markets in Brazil. Since 4G technologies are not rolled out randomly, provision commitments in contracts between 4G national operators and Brazilian regulatory agency of telecommunications (ANATEL) work as an instrumental variable to internet presence. The average increase of mobile operators observed in sample is responsible for a reduction of 8 percent in formal employment contracts (about 40 percent of the variation in period). This reduction is explained by (i) reduced turnover and by (ii) displacement effects. Consistent with the routinization hypothesis, 4G expansion shifts labor demand away from manual and routine tasks. This, in turn, has benefited more high-skilled workers, increasing the share of college-graduates in the labor force and the average skill level index of local labor markets. Effects are driven by the extremes of the distribution of technological intensity but there are no changes in the industry-composition of labor markets. I also show suggestive evidence that mobile broadband is associated with job polarization.

寬頻擴散可促進國家之生產力、就業、經濟成長及國家競爭力等，若能精準找出促進寬頻擴散之關鍵影響因素，將有利於政府集中資源有效率地推動寬頻發展。本研究提出研究問題與假說，以Rogers (2003)及Hall (2006)所提出影響創新擴散速率之社經因素、採用成本、採用效益、網路效應、資訊及不確定性及產業環境等6大因素面向為基礎，蒐集OECD國家及台灣等31國家相關資料，挑選Gompertz模型進行固定寬頻擴散Panel資料迴歸分析，發現各因素在全期及不同擴散階段有不同之顯著性與影響程度，表示分階段分析有其必要性。擴散初期之關鍵影響因素為收入、教育水準、平台競爭程度、人口密度及實施LLU累積年度等5項，而擴散後期之關鍵影響因素為寬頻價格、網際網路內容、決定採用時固定寬頻用戶比例、撥接用戶比例及擁有PC家庭比例等5項，可作為政府及業者於不同擴散階段精準投入資源以有效推動寬頻擴散之參考。 本研究續以前述分析結果選取日本、南韓、美國、丹麥、瑞士及台灣進行實際擴散比較，確認前述關鍵影響因素挑選之有效性。擴散初期，台灣有高人口密度優勢，若能提早推動寬頻並推動促進競爭措施，可促進初期之快速擴散。擴散後期，台灣國際排名退步，原因為寬頻價格過高，故此階段政府及業者應特別確保寬頻價格能夠使潛在採用者有能力並願意付費採用，才能促使寬頻持續有效擴散。 最後，本研究採用與固定寬頻相同迴歸分析模型對FTTX及行動寬頻分別進行分析後，有關行動寬頻，教育水準、寬頻價格、決定採用時行動寬頻用戶比例、人口密度、網際網路內容、使用固定寬頻語音服務比例、決定採用時FTTX用戶比例及使用網際網路家庭比例等8項變數有顯著效應；有關行動寬頻，收入、寬頻價格、網際網路內容、決定採用時行動寬頻用戶比例、使用網際網路家庭比例及人口密度等6項變數有顯著效應。因此，政府及業者若擬促進特定寬頻服務發展，仍須針對其服務特性推動特定之政策或策略。其中，寬頻價格、網際網路內容、網路效應及使用網際網路家庭比例等4項因素對FTTX及行動寬頻服務之影響類似，而此4個因素與固定寬頻後期擴散之關鍵影響因素較相近，因此，對於已存在市場的服務，即使是後來以較佳品質或功能之新服務型式提供，新服務之關鍵影響因素仍較接近已存在市場服務關鍵因素。 總之，本研究不同於過去文獻，以創新擴散理論為基礎，以國家層級資料量化分析與探討寬頻擴散之關鍵影響因素，除分別提供政策及管理建議供政府及業者參考外，亦補強Rogers (2003)及Hall (2006)所提出創新擴散理論未釐清與比較創新擴散影響因素在不同擴散階段影響之不足。 / Broadband diffusion may enhance innovation, productivity, employment, economic growth, and, ultimately, national competitiveness. If key determinants for broadband diffusion are identified, governments can align its resources with them to effectively promote the diffusion. Based on the determinants of the diffusion rate identified by Rogers (2003) and Hall (2006), this research compiled data available about OECD countries as well as Taiwan to implement overall and staged panel regressions on fixed broadband diffusion by adopting Gompertz model. The findings indicate that the significance of the determinants varies between overall and staged analysis, which consequently justifies the necessity of a staged analysis. The key determinants in the early stage are income, education level, platform competition, population density, and the accumulated years of implementing LLU policy; however, in the late stage they are broadband price, Internet content, network effect, the penetration of dial-up users, and percentage of household with computer. Governments may more accurately promote broadband diffusion according to different key determinants in different stages. This research further compared the real fixed broadband diffusion of Japan, South Korea, USA, Denmark, Switzerland, and Taiwan based on the previous analysis results. The findings generally justify the choice of key determinants in the previous analysis. In the early stage, Taiwan had the advantage of high population density. If the government could have promoted fixed broad banded services and market competition earlier, the penetration would have grown much faster. In the late stage, since the broadband price was too high in Taiwan, its international ranking of fixed broadband penetration declined. Therefore, in order to further promote the diffusion of fixed broadband, the government should have ensured that the price was low enough to convince the potential adoptors to purchase broadband services. Finally, this research adopted the same approach as that of previous fixed broadband to analyze the diffusion of FTTX and mobile broadband, respectively. Education level, broadband price, network effect of FTTX, network effect of mobile broadband, Internet content, population density, percentage of household with computer, and the penetration of fixed VOIP users have significant effect on FTTX diffusion. However, income, broadband price, network effect of mobile broadband, Internet content, population density, and percentage of household with computer have significant effect on mobile broadband diffusion. Therefore, governments or operators should tailor their policies or strategies for specific services. The effects of broadband price, Internet content, network effect, and percentage of household with computer are similar in both FTTX and mobile broadband, and they are also similar to the key determinants of fixed broadband diffusion in the late stage. Therefore, even though a new service with better quality or function is introduced in an existing market, its key determinants are more similar to those of the existing service depending on its diffusion stage. In conclusion, different from previous research, this one applied national-level data to quantatively analyzed and explore the key determinants of broadband diffusion based on innovation diffusion theory. The research findings not only propose policy and management suggestions to governments and service providers, but also supplement the the theory proposed by Rogers (2003) and Hall (2006), which did not identify and compare the determinants of innovation in different diffusion stages.

Over the last few years, there has been a signifi cant rise in the mobile broadband users worldwide. Recently, operators around the world have been improving the 3G networks by providing Dual Carrier-High Speed Packet Access+ (DC-HSPA+) services in both uplink and downlink to the users. However, the delay performance of the operational DC-HSPA+ networks is not focused. Firstly, we investigate and analyze the e ffect of operator service on One-Way Delay (OWD) and Jitter. Secondly, we investigate the treatment of protocols by 3G network for random packet sizes and random Inter Packet Duration (IPD). Thirdly, we investigate the eff ect of background load on OWD for packets generated at very low rate. Fourthly, we investigate the impact of constant IPD and streaming. Fifthly, we investigate the effects of shrinking the interval of IPD on OWD in 3G networks. Lastly, we investigate the OWD for Constant-Bit-Rate (CBR) and Variable-Bit-Rate (VBR) transmission patterns. Firstly, results show that OWD in the DC-HSPA+ networks is lower compared to the OWD in the preceding HSUPA networks and OWD strongly depends on packet-size at lower rates. Secondly, the 3G networks treat User Datagram Protocol (UDP), Transmission Control Protocol (TCP) and Internet Control Message Protocol (ICMP) protocols similarly for random packet size and random IPD. Thirdly, at high rates OWD depends on E-TFCE-DCH Transport Format Combination (ETFC) grants. Thirdly, the results also indicate that background load has a signi ficant impact on the end-to-end OWD. Fourthly, for low rates, OWD depends on packet sizes and for high rates OWD depends on IPD and for higher rates, OWD depends on E-TFC grants. Fifthly, we also observe: Shrinking the interval of IPD does not necessarily improve the OWD performance. Lastly, results also indicate that the VBR pattern has a better OWD performance than the CBR pattern for low transmission rates.

Providing mobile broadband (MBB) coverage to passengers in planes (and other yingobjects) has been one of the very important requirements by airline industry for sometime. With the emergence of high-capacity wireless network concepts, there is a renewedeort in dening systems based on 5G (also dened as NR, new radio) for air-to-ground(A2G) communication. When passenger planes have been taken into consideration, a fewhundreds of passengers may need to be supported, thus requiring a high-capacity backhaullink. When 5G is used for such A2G link, beamforming and other advanced physicallayer techniques can be used between the ground stations and ying objects to obtainhigh-data rate and reliable new radio link. This masters thesis work includes link andsystem level evaluations of such NR systems when beamforming, large bandwidth, higherantenna gains, coordination between ground stations, etc., are deployed. The evaluationswere carried out in Ericsson's internal state-of-the-art simulators. The study providesbaseline for system design principles for future A2G system based on NR. Also a properpropagation model for A2G communication has been identied and beamforming solutionwith other related techniques that could be used in A2G scenario have been investigated. / Att tillhandahålla mobil bredbandstäckning till passagerare i flygplan (samt andraluftburna föremål) har varit ett viktigt krav från flygsindustrin på senare tid. Medframväxten av trådlösa nätverkskoncept med hög kapacitet har en förnyad insats uppståttför att definiera system baserade på 5G (också kallat New Radio (NR)) för Airplane-to-Ground (A2G) kommunikation. För passagerarplan så kan hundratals passagerare behövatäckning, vilket kräver en backhaul-länk med hög kapacitet. När 5G används för en sådanA2G-länk så kan såkallad lobformning och andra avancerade tekniker användas mellanmarkstationerna och flygande objekt för att erhålla hög datahastighet och tillförlitlig radiolänk. I denna uppsats ingår länk- och systemnivåutvärderningar av sådana NR-systemnär lobformning, stor bandbredd, antenn-amplifikation, koordinering mellan markstationeretc utplaceras. Utvärderingarna genomfördes i Ericssons interna simulatorer. Studienger vägledning för principer inom systemdesign för framtida A2G-system baserat på NR.En lämplig utbredningsmodell för radiovågor för A2G-kommunikation har identifieratsoch en metod för lobformning och andra relaterade tekniker som kan användas i A2Gscenariothar också undersökts.

La quinta generación de redes móviles (5G) se encuentra a la vuelta de la esquina. Se espera provea de beneficios extraordinarios a la población y que resuelva la mayoría de los problemas de las redes 4G actuales. El éxito de 5G, cuya primera fase de estandarización ha sido completada, depende de tres pilares: comunicaciones tipo-máquina masivas, banda ancha móvil mejorada y comunicaciones ultra fiables y de baja latencia (mMTC, eMBB y URLLC, respectivamente). En esta tesis nos enfocamos en el primer pilar de 5G, mMTC, pero también proveemos una solución para lograr eMBB en escenarios de distribución masiva de contenidos. Específicamente, las principales contribuciones son en las áreas de: 1) soporte eficiente de mMTC en redes celulares; 2) acceso aleatorio para el reporte de eventos en redes inalámbricas de sensores (WSNs); y 3) cooperación para la distribución masiva de contenidos en redes celulares. En el apartado de mMTC en redes celulares, esta tesis provee un análisis profundo del desempeño del procedimiento de acceso aleatorio, que es la forma mediante la cual los dispositivos móviles acceden a la red. Estos análisis fueron inicialmente llevados a cabo por simulaciones y, posteriormente, por medio de un modelo analítico. Ambos modelos fueron desarrollados específicamente para este propósito e incluyen uno de los esquemas de control de acceso más prometedores: access class barring (ACB). Nuestro modelo es uno de los más precisos que se pueden encontrar en la literatura y el único que incorpora el esquema de ACB. Los resultados obtenidos por medio de este modelo y por simulación son claros: los accesos altamente sincronizados que ocurren en aplicaciones de mMTC pueden causar congestión severa en el canal de acceso. Por otro lado, también son claros en que esta congestión se puede prevenir con una adecuada configuración del ACB. Sin embargo, los parámetros de configuración del ACB deben ser continuamente adaptados a la intensidad de accesos para poder obtener un desempeño óptimo. En la tesis se propone una solución práctica a este problema en la forma de un esquema de configuración automática para el ACB; lo llamamos ACBC. Los resultados muestran que nuestro esquema puede lograr un desempeño muy cercano al óptimo sin importar la intensidad de los accesos. Asimismo, puede ser directamente implementado en redes celulares para soportar el tráfico mMTC, ya que ha sido diseñado teniendo en cuenta los estándares del 3GPP. Además de los análisis descritos anteriormente para redes celulares, se realiza un análisis general para aplicaciones de contadores inteligentes. Es decir, estudiamos un escenario de mMTC desde la perspectiva de las WSNs. Específicamente, desarrollamos un modelo híbrido para el análisis de desempeño y la optimización de protocolos de WSNs de acceso aleatorio y basados en cluster. Los resultados muestran la utilidad de escuchar el medio inalámbrico para minimizar el número de transmisiones y también de modificar las probabilidades de transmisión después de una colisión. En lo que respecta a eMBB, nos enfocamos en un escenario de distribución masiva de contenidos, en el que un mismo contenido es enviado de forma simultánea a un gran número de usuarios móviles. Este escenario es problemático, ya que las estaciones base de la red celular no cuentan con mecanismos eficientes de multicast o broadcast. Por lo tanto, la solución que se adopta comúnmente es la de replicar e contenido para cada uno de los usuarios que lo soliciten; está claro que esto es altamente ineficiente. Para resolver este problema, proponemos el uso de esquemas de network coding y de arquitecturas cooperativas llamadas nubes móviles. En concreto, desarrollamos un protocolo para la distribución masiva de contenidos, junto con un modelo analítico para su optimización. Los resultados demuestran que el modelo propuesto es simple y preciso, y que el protocolo puede reducir el con / La cinquena generació de xarxes mòbils (5G) es troba molt a la vora. S'espera que proveïsca de beneficis extraordinaris a la població i que resolga la majoria dels problemes de les xarxes 4G actuals. L'èxit de 5G, per a la qual ja ha sigut completada la primera fase del qual d'estandardització, depén de tres pilars: comunicacions tipus-màquina massives, banda ampla mòbil millorada, i comunicacions ultra fiables i de baixa latència (mMTC, eMBB i URLLC, respectivament, per les seues sigles en anglés). En aquesta tesi ens enfoquem en el primer pilar de 5G, mMTC, però també proveïm una solució per a aconseguir eMBB en escenaris de distribució massiva de continguts. Específicament, les principals contribucions són en les àrees de: 1) suport eficient de mMTC en xarxes cel·lulars; 2) accés aleatori per al report d'esdeveniments en xarxes sense fils de sensors (WSNs); i 3) cooperació per a la distribució massiva de continguts en xarxes cel·lulars. En l'apartat de mMTC en xarxes cel·lulars, aquesta tesi realitza una anàlisi profunda de l'acompliment del procediment d'accés aleatori, que és la forma mitjançant la qual els dispositius mòbils accedeixen a la xarxa. Aquestes anàlisis van ser inicialment dutes per mitjà de simulacions i, posteriorment, per mitjà d'un model analític. Els models van ser desenvolupats específicament per a aquest propòsit i inclouen un dels esquemes de control d'accés més prometedors: el access class barring (ACB). El nostre model és un dels més precisos que es poden trobar i l'únic que incorpora l'esquema d'ACB. Els resultats obtinguts per mitjà d'aquest model i per simulació són clars: els accessos altament sincronitzats que ocorren en aplicacions de mMTC poden causar congestió severa en el canal d'accés. D'altra banda, també són clars en què aquesta congestió es pot previndre amb una adequada configuració de l'ACB. No obstant això, els paràmetres de configuració de l'ACB han de ser contínuament adaptats a la intensitat d'accessos per a poder obtindre unes prestacions òptimes. En la tesi es proposa una solució pràctica a aquest problema en la forma d'un esquema de configuració automàtica per a l'ACB; l'anomenem ACBC. Els resultats mostren que el nostre esquema pot aconseguir un acompliment molt proper a l'òptim sense importar la intensitat dels accessos. Així mateix, pot ser directament implementat en xarxes cel·lulars per a suportar el trànsit mMTC, ja que ha sigut dissenyat tenint en compte els estàndards del 3GPP. A més de les anàlisis descrites anteriorment per a xarxes cel·lulars, es realitza una anàlisi general per a aplicacions de comptadors intel·ligents. És a dir, estudiem un escenari de mMTC des de la perspectiva de les WSNs. Específicament, desenvolupem un model híbrid per a l'anàlisi de prestacions i l'optimització de protocols de WSNs d'accés aleatori i basats en clúster. Els resultats mostren la utilitat d'escoltar el mitjà sense fil per a minimitzar el nombre de transmissions i també de modificar les probabilitats de transmissió després d'una col·lisió. Pel que fa a eMBB, ens enfoquem en un escenari de distribució massiva de continguts, en el qual un mateix contingut és enviat de forma simultània a un gran nombre d'usuaris mòbils. Aquest escenari és problemàtic, ja que les estacions base de la xarxa cel·lular no compten amb mecanismes eficients de multicast o broadcast. Per tant, la solució que s'adopta comunament és la de replicar el contingut per a cadascun dels usuaris que ho sol·liciten; és clar que això és altament ineficient. Per a resoldre aquest problema, proposem l'ús d'esquemes de network coding i d'arquitectures cooperatives anomenades núvols mòbils. En concret, desenvolupem un protocol per a realitzar la distribució massiva de continguts de forma eficient, juntament amb un model analític per a la seua optimització. Els resultats demostren que el model proposat és simple i precís / The 5th generation (5G) of mobile networks is just around the corner. It is expected to bring extraordinary benefits to the population and to solve the majority of the problems of current 4th generation (4G) systems. The success of 5G, whose first phase of standardization has concluded, relies in three pillars that correspond to its main use cases: massive machine-type communication (mMTC), enhanced mobile broadband (eMBB), and ultra-reliable low latency communication (URLLC). This thesis mainly focuses on the first pillar of 5G: mMTC, but also provides a solution for the eMBB in massive content delivery scenarios. Specifically, its main contributions are in the areas of: 1) efficient support of mMTC in cellular networks; 2) random access (RA) event-reporting in wireless sensor networks (WSNs); and 3) cooperative massive content delivery in cellular networks. Regarding mMTC in cellular networks, this thesis provides a thorough performance analysis of the RA procedure (RAP), used by the mobile devices to switch from idle to connected mode. These analyses were first conducted by simulation and then by an analytical model; both of these were developed with this specific purpose and include one of the most promising access control schemes: the access class barring (ACB). To the best of our knowledge, this is one of the most accurate analytical models reported in the literature and the only one that incorporates the ACB scheme. Our results clearly show that the highly-synchronized accesses that occur in mMTC applications can lead to severe congestion. On the other hand, it is also clear that congestion can be prevented with an adequate configuration of the ACB scheme. However, the configuration parameters of the ACB scheme must be continuously adapted to the intensity of access attempts if an optimal performance is to be obtained. We developed a practical solution to this problem in the form of a scheme to automatically configure the ACB; we call it access class barring configuration (ACBC) scheme. The results show that our ACBC scheme leads to a near-optimal performance regardless of the intensity of access attempts. Furthermore, it can be directly implemented in 3rd Generation Partnership Project (3GPP) cellular systems to efficiently handle mMTC because it has been designed to comply with the 3GPP standards. In addition to the analyses described above for cellular networks, a general analysis for smart metering applications is performed. That is, we study an mMTC scenario from the perspective of event detection and reporting WSNs. Specifically, we provide a hybrid model for the performance analysis and optimization of cluster-based RA WSN protocols. Results showcase the utility of overhearing to minimize the number of packet transmissions, but also of the adaptation of transmission parameters after a collision occurs. Building on this, we are able to provide some guidelines that can drastically increase the performance of a wide range of RA protocols and systems in event reporting applications. Regarding eMBB, we focus on a massive content delivery scenario in which the exact same content is transmitted to a large number of mobile users simultaneously. Such a scenario may arise, for example, with video streaming services that offer a particularly popular content. This is a problematic scenario because cellular base stations have no efficient multicast or broadcast mechanisms. Hence, the traditional solution is to replicate the content for each requesting user, which is highly inefficient. To solve this problem, we propose the use of network coding (NC) schemes in combination with cooperative architectures named mobile clouds (MCs). Specifically, we develop a protocol for efficient massive content delivery, along with the analytical model for its optimization. Results show the proposed model is simple and accurate, and the protocol can lead to energy savings of up to 37 percent when compared to the traditional approach. / Leyva Mayorga, I. (2018). On reliable and energy efficient massive wireless communications: the road to 5G [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/115484 / TESIS

Computer networks are in the scope of the IEEE organization normalized by the 802 board which currently comprises six working groups for wireless communications. IEEE 802.11 for wireless local area networks, IEEE  802.15 for wireless personal area networks, IEEE 802.16 for wireless metropolitan area networks, IEEE 802.20 for mobile broadband wireless access, IEEE 802.21 for media independent handover and IEEE 802.22 for wireless regional area networks. This master's thesis focuses on a security analysis of particular standards, describes threats, vulnerabilities, current security measures and mutually compares wireless specifications from a security point of view. The conclusion is devoted to overall evaluation of the project, to its contributions, possible enhancements and continuation in the form of consequential studies.