Dissertations / Theses on the topic 'Broadband Wireless Access [BWA]'

The “WLAN in Disaster Emergency Response” (WIDER) project has developed and implemented an emergency communication system. It provides network and communication services to relief organizations. In order to guarantee the stable and efficient connectivity with a high quality of service (QoS) for the end user, and to make the WIDER system more adaptive to the disaster area, the IEEE 802.16 specification based broadband wireless access solution is adopted. This thesis work aims at evaluating and testing the WIDER system integrated with WiMAX. By learning and analyzing the technology, the benefits and perspective for WIDER using WiMAX are described. A WiMAX solution was configured and integrated into the WIDER system. A series of tests and measurements provide us the performance of the WiMAX solution in throughput, QoS, and reality. The tests helped us to learn and verify the improvements for WIDER due to WiMAX.
“WLAN in Disaster Emergency Response” (WIDER) projektet har utvecklat och implementerat ett kommunikationssystem för katastrof situationer. Systemet tillhandahåller nätverk- och kommunikationstjänster för hjälporganisationer. För att garantera en stabil och effektiv anslutning med hög Quality of Service för användarna samt göra WIDER systemet mer anpassbart för katastrofområden, kommer Broadband wireless access som är baserade på IEEE 802.16 specifikationen att användas. Det här examensarbetet har som målsättning att utvärdera och testa WIDER med WiMax tekniken, vi beskriver olika fördelar och synvinklar med att använda WiMax genom att lära oss och analysera tekniken. En WiMax lösning konfigurerades och integrerades i WIDER systemet. En rad tester och mätningar visar WiMax-lösningens prestanda i form av throughput, Quality of Service och realitet. Testerna lärde oss och hjälpte oss att verifiera förbättringarna i WIDER i och med användningen av WiMax.

IEEE 802. 16 définit un mécanisme d’allocation de la bande passante basé sur réservation. Dans ce mécanisme, sont définis les deux principaux modes de polling : le polling mode unicast et le polling mode contention. Il faudrait avoir un mécanisme pour adopter les deux modes de polling afin d’optimiser la performance. Nous proposons un simple mais efficace mécanisme de polling pour adopter les deux modes de polling d’une manière efficiente et équitable, qui optimise enfin la performance. Le mode contention est utilisé par les applications comme nrtPS et BE pour demander la bande passante à lien montant. Le nombre de la bande passante alloué aux requêtes sur contention va influencer d’une façon significative la performance. Nous analysons et développons un simple modèle mathématique pour évaluer la performance. Une période optimale contention-request dans cette trame est introduite. La taille optimale est aussi influencée par le nombre des terminaux dans le réseau, ceci est aussi analysé

Un dels aspectes claus en el disseny i gestió de les xarxes sense fils d'accés de banda ampla és l'ús eficient dels recursos radio. Des del punt de vista de l'operador, l'ample de banda és un bé escàs i preuat que s´ha d'explotar i gestionar de la forma més eficient possible tot garantint la qualitat del servei que es vol proporcionar. Per altra banda, des del punt de vista del usuari, la qualitat del servei ofert ha de ser comparable al de les xarxes fixes, requerint així un baix retard i una baixa pèrdua de paquets per cadascun dels fluxos de dades entre la xarxa i l'usuari. Durant els darrers anys s´han desenvolupat nombroses tècniques i algoritmes amb l'objectiu d'incrementar l'eficiència espectral. Entre aquestes tècniques destaca l'ús de múltiples antenes al transmissor i al receptor amb l'objectiu de transmetre diferents fluxos de dades simultaneament sense necessitat d'augmentar l'ample de banda. Per altra banda, la optimizació conjunta de la capa d'accés al medi i la capa física (fent ús de l'estat del canal per tal de gestionar de manera optima els recursos) també permet incrementar sensiblement l'eficiència espectral del sistema.

L'objectiu d'aquesta tesi és l'estudi i desenvolupament de noves tècniques d'adaptació de l'enllaç i gestió dels recursos ràdio aplicades sobre sistemes d'accés ràdio de propera generació (Beyond 3G). Els estudis realitzats parteixen de la premissa que el transmisor coneix (parcialment) l'estat del canal i que la transmissió es realitza fent servir un esquema multiportadora amb múltiples antenes al transmisor i al receptor. En aquesta tesi es presenten dues línies d'investigació, la primera per casos d'una sola antenna a cada banda de l'enllaç, i la segona en cas de múltiples antenes. En el cas d'una sola antena al transmissor i al receptor, un nou esquema d'assignació de recursos ràdio i priorització dels paquets (scheduling) és proposat i analitzat integrant totes dues funcions sobre una mateixa entitat (cross-layer). L'esquema proposat té com a principal característica la seva baixa complexitat i que permet operar amb transmissions multimedia. Alhora, posteriors millores realitzades per l'autor sobre l'esquema proposat han permès també reduir els requeriments de senyalització i combinar de forma óptima usuaris d'alta i baixa mobilitat sobre el mateix accés ràdio, millorant encara més l'eficiència espectral del sistema. En cas d'enllaços amb múltiples antenes es proposa un nou esquema que combina la selecció del conjunt optim d'antenes transmissores amb la selecció de la codificació espai- (frequència-) temps. Finalment es donen una sèrie de recomanacions per tal de combinar totes dues línies d'investigació, així con un estat de l'art de les tècniques proposades per altres autors que combinen en part la gestió dels recursos ràdio i els esquemes de transmissió amb múltiples antenes.
Uno de los aspectos claves en el diseño y gestión de las redes inalámbricas de banda ancha es el uso eficiente de los recursos radio. Desde el punto de vista del operador, el ancho de banda es un bien escaso y valioso que se debe explotar y gestionar de la forma más eficiente posible sin afectar a la calidad del servicio ofrecido. Por otro lado, desde el punto de vista del usuario, la calidad del servicio ha de ser comparable al ofrecido por las redes fijas, requiriendo así un bajo retardo y una baja tasa de perdida de paquetes para cada uno de los flujos de datos entre la red y el usuario. Durante los últimos años el número de técnicas y algoritmos que tratan de incrementar la eficiencia espectral en dichas redes es bastante amplio. Entre estas técnicas destaca el uso de múltiples antenas en el transmisor y en el receptor con el objetivo de poder transmitir simultáneamente diferentes flujos de datos sin necesidad de incrementar el ancho de banda. Por otro lado, la optimización conjunta de la capa de acceso al medio y la capa física (utilizando información de estado del canal para gestionar de manera óptima los recursos) también permite incrementar sensiblemente la eficiencia espectral del sistema.
El objetivo de esta tesis es el estudio y desarrollo de nuevas técnicas de adaptación del enlace y la gestión de los recursos radio, y su posterior aplicación sobre los sistemas de acceso radio de próxima generación (Beyond 3G). Los estudios realizados parten de la premisa de que el transmisor conoce (parcialmente) el estado del canal a la vez que se considera que la transmisión se realiza sobre un sistema de transmisión multiportadora con múltiple antenas en el transmisor y el receptor. La tesis se centra sobre dos líneas de investigación, la primera para casos de una única antena en cada lado del enlace, y la segunda en caso de múltiples antenas en cada lado. Para el caso de una única antena en el transmisor y en el receptor, se ha desarrollado un nuevo esquema de asignación de los recursos radio así como de priorización de los paquetes de datos (scheduling) integrando ambas funciones sobre una misma entidad (cross-layer). El esquema propuesto tiene como principal característica su bajo coste computacional a la vez que se puede aplicar en caso de transmisiones multimedia. Posteriores mejoras realizadas por el autor sobre el esquema propuesto han permitido también reducir los requisitos de señalización así como combinar de forma óptima usuarios de alta y baja movilidad. Por otro lado, en caso de enlaces con múltiples antenas en transmisión y recepción, se presenta un nuevo esquema de adaptación en el cual se combina la selección de la(s) antena(s) transmisora(s) con la selección del esquema de codificación espacio-(frecuencia-) tiempo. Para finalizar, se dan una serie de recomendaciones con el objetivo de combinar ambas líneas de investigación, así como un estado del arte de las técnicas propuestas por otros autores que combinan en parte la gestión de los recursos radio y los esquemas de transmisión con múltiples antenas.
In Broadband Wireless Access systems the efficient use of the resources is crucial from many points of views. From the operator point of view, the bandwidth is a scarce, valuable, and expensive resource which must be exploited in an efficient manner while the Quality of Service (QoS) provided to the users is guaranteed. On the other hand, a tight delay and link quality constraints are imposed on each data flow hence the user experiences the same quality as in fixed networks. During the last few years many techniques have been developed in order to increase the spectral efficiency and the throughput. Among them, the use of multiple antennas at the transmitter and the receiver (exploiting spatial multiplexing) with the joint optimization of the medium access control layer and the physical layer parameters.
In this Ph.D. thesis, different adaptive techniques for B3G multicarrier wireless systems are developed and proposed focusing on the SS-MC-MA and the OFDM(A) (IEEE 802.16a/e/m standards) communication schemes. The research lines emphasize into the adaptation of the transmission having (Partial) knowledge of the Channel State Information for both; single antenna and multiple antenna links. For single antenna links, the implementation of a joint resource allocation and scheduling strategy by including adaptive modulation and coding is investigated. A low complexity resource allocation and scheduling algorithm is proposed with the objective to cope with real- and/or non-real- time requirements and constraints. A special attention is also devoted in reducing the required signalling. However, for multiple antenna links, the performance of a proposed adaptive transmit antenna selection scheme jointly with space-time block coding selection is investigated and compared with conventional structures. In this research line, mainly two optimizations criteria are proposed for spatial link adaptation, one based on the minimum error rate for fixed throughput, and the second focused on the maximisation of the rate for fixed error rate. Finally, some indications are given on how to include the spatial adaptation into the investigated and proposed resource allocation and scheduling process developed for single antenna transmission.

Broadband speeds, Internet literacy and digital technologies have been steadily evolving over the last decade. Broadband infrastructure has become a key asset in today’s society, enabling innovation, driving economic efficiency and stimulating cultural inclusion. However, populations living in remote and rural communities are unable to take advantage of these trends. Globally, a significant part of the world population is still deprived of basic access to the Internet. Broadband Wireless Access (BWA) networks are regarded as a viable solution for providing Internet access to populations living in rural regions. In recent years, Wireless Internet Service Providers (WISPs) and community organizations around the world proved that rural BWA networks can be an effective strategy and a profitable business. This research began by deploying a BWA network testbed, which also provides Internet access to several remote communities in the harsh environment of the Scottish Highlands and Islands. The experience of deploying and operating this network pointed out three unresolved research challenges that need to be addressed to ease the path towards widespread deployment of rural BWA networks, thereby bridging the rural-urban broadband divide. Below, our research contributions are outlined with respect to these challenges. Firstly, an effective planning paradigm for deploying BWA networks is proposed: incremental planning. Incremental planning allows to anticipate return of investment and to overcome the limited network infrastructure (e.g., backhaul fibre links) in rural areas. I have developed a software tool called IncrEase and underlying network planning algorithms to consider a varied set of operational metrics to guide the operator in identifying the regions that would benefit the most from a network upgrade, automatically suggesting the best long-term strategy to the network administrator. Second, we recognize that rural and community networks present additional issues for network management. As the Internet uplink is often the most expensive part of the operational expenses for such deployments, it is desirable to minimize overhead for network management. Also, unreliable connectivity between the network operation centre and the network being managed can render traditional centralized management approaches ineffective. Finally, the number of skilled personnel available to maintain such networks is limited. I have developed a distributed network management platform called Stix for BWA networks, to make it easy to manage such networks for rural/community deployments and WISPs alike while keeping the network management infrastructure scalable and flexible. Our approach is based on the notions of goal-oriented and in-network management: administrators graphically specify network management activities as workflows, which are run in the network on a distributed set of agents that cooperate in executing those workflows and storing management information. The Stix system was implemented on low-cost and small form-factor embedded boards and shown to have a low memory footprint. Third, the research focus moves to the problem of assessing broadband coverage and quality in a given geographic region. The outcome is BSense, a flexible framework that combines data provided by ISPs with measurements gathered by distributed software agents. The result is a census (presented as maps and tables) of the coverage and quality of broadband connections available in the region of interest. Such information can be exploited by ISPs to drive their growth, and by regulators and policy makers to get the true picture of broadband availability in the region and make informed decisions. In exchange for installing the multi-platform measurement software (that runs in the background) on their computers, users can get statistics about their Internet connection and those in their neighbourhood. Finally, the lessons learned through this research are summarised. The outcome is a set of suggestions about how the deployment and operation of rural BWA networks, including our own testbed, can be made more efficient by using the proper tools. The software systems presented in this thesis have been evaluated in lab settings and in real networks, and are available as open-source software.

This thesis deals with the characteristics and performance analysis of hybrid optical-wireless 802.11 broadband access networks. The main focus of this work is on the behaviour and performance of the IEEE 802.11 MAC layer when Radio over Fibre technology is used to distribute Radio Frequency signals from a Central Site to Remote Antenna Units. Data throughput impairments due to constraints imposed by the IEEE 802.11 MAC are considered in Single Mode Fibre systems. The results presented in this thesis are based on the current DCF access scheme specifications using both the Basic Access and RTS/CTS Access mechanisms (at the MAC layer), as well as TCP and UDP protocols (within the transport layer). It is shown that the length of the fibre is constricted to a maximum limit in a standard hybrid system. However, with minimal changes to the parameters of IEEE 802.11 standard this limit can be expanded. It is also realised that data throughput decreases with different rates (depending on parameters chosen) as fibre length increases. It has been observed that the network fails long before physical layer limitations set in due to the timeout values defined within the MAC protocol. In this thesis experimental enquiries are first used to provide a set of validation points before extending these results by simulations using the NS-2 platform. Mathematical approximations are then presented to these results that would allow designers of Radio over Fibre systems to quickly and accurately predict the data throughput and performance behaviour given the specific parameters of their network. Finally, two different strategies are investigated within an 802.11 Fibre Friendly MAC that significantly enhance the data throughput. Due to the common functionality of the MAC layer the basis of this work can be applied to a number of IEEE 802.11 systems, including 802.11a/b/g networks. To the knowledge of the author this is the first analysis of this kind for a long reach fibre system.

The ever-increasing demand for high date rate is beyond what is provided by the present wireless and wired access networks. Radio-over-fiber (RoF) technology which can provide broadband wireless access has been considered the most practical and efficient solution. In recent years, RoF with coherent detection has been shown to have better performance than that with direct detection in terms of receiver sensitivity and spectral efficiency. However, RoF with coherent detection suffers from phase noise introduced from both the transmitter and local oscillator (LO) laser sources, which degrades the performance significantly. This study is focused on coherent RoF links for broadband wireless access networks. The thesis consists of four parts. In the first part, a new approach to cancel the phase noise and the unstable frequency difference introduced from the transmitter and LO laser sources based on digital signal processing (DSP) in an RoF link with coherent detection is presented. The proposed schemes rival the RoF link with direct detection in complexity while maintaining a high receiver sensitivity. In addition, a high spectral efficiency coherent RoF link with phase noise cancellation, which can detect both intensity- and phase- modulated signals carried by the same optical carrier, is studied and demonstrated. In the second part, to achieve full-duplex transmission and increase the capacity of an RoF link, radio over wavelength division multiplexing passive optical network (WDM-PON) is studied. To eliminate the requirements of light sources and wavelength management at the optical network units (ONUs), which reduces the cost and eases the installation for a radio over WDM-PON system, a new approach to reuse the downstream wavelength at the ONU with coherent detection and DSP at the optical line terminal (OLT) is investigated. The performance in terms of error vector magnitude (EVM) and bit rate error (BER) is evaluated for both downlink and uplink. In the scheme, the coherent detection improves the receiver sensitivity for the uplink and compensate for the degraded data transmission performance due to the utilization of a wavelength-reused downstream optical signal. Furthermore, since the future internet traffic will become highly symmetric, a symmetrical radio over a colorless WDM passive optical network (PON) with wavelength reuse based on polarization multiplexing and coherent detection is proposed and studied. In the third part, a coherent RoF link based on optical single sideband with no optical carrier (OSSB) modulation with low-cost free-running laser sources for ultra-dense wavelength division multiplexing passive optical networks (UDWDM-PONs) is studied. In a UDWDM-RoF-PON, the channel spacing is very small, thus a WDM filter may not be able to de-multiplex the ultra-dense channels. However, through coherent detection, the channel separation can be realized by using electrical filters at the output of the coherent receiver. In addition, to utilize the spectrum in each channel more efficiently, OSSB modulation is employed. In the proposed scheme, an RoF signal based OSSB modulation with coherent detection is experimentally demonstrated. The channel spacing can be as narrow as 3 GHz. Finally, for 5th generation wireless systems (5G), multi-input and multi-output (MIMO) is a key technology which can multiple the capacity. To seamlessly integrate MIMO into RoF links, it is required that an RoF link can transmit multiple wireless signals over a single wavelength. To enable 4 × 4 MIMO, in the fourth part, an RoF link to transmit four wireless signals with an identical microwave center frequency without using frequency-division multiplexing (FDM) over a single optical wavelength based on optical independent sideband (OISB) modulation and optical orthogonal modulation incorporating optical coherent detection and digital signal processing (DSP) is studied. To increase the spectral efficiency further, a novel high spectral efficiency (20.62 bit/s/Hz) RoF link based on coherent detection and DSP with the spectral efficiency improved by employing both intensity and phase modulation and polarization multiplexing to transmit four microwave signals over a single optical carrier is investigated.

During the last century, the significant increase in electricity demand, and its consequences, has appeared as a serious concern for the utility companies, but no essential change has been applied to the conventional power grid infrastructure till now. Recently, researchers have identified efficient control and power distribution mechanisms as the immediate challenges for conventional power grids. Hence, the next step for conventional power grid toward Smart Grid is to provide energy efficiency management along with higher reliability via smart services, in which the application of Information and Communication Technology (ICT) is inevitable. ICT introduces powerful tools to comply with the smart grid requirements. Among various ICT properties, the telecommunication network plays a key role for providing a secure infrastructure. The two-way digital communication system provides an interaction between energy suppliers and consumers for managing, controlling and optimizing energy distribution. We can also define the smart grid as a two-way flow of energy and control information, where the electricity consumers can generate energy using green energy resources. The main objective of this thesis is to select an effective communication infrastructure to support the smart grid services by considering wireless and optical communication technologies. Fiber-wireless (FiWi) networks are considered as a potential solution to provide a fast and reliable network backbone with the optical access network integration and the flexibility and mobility of the wireless network. Therefore, we adopt the integration of the wireless sensor network (WSN) to Ethernet Passive Optical Network (EPON) as a broadband access network to transmit smart meter data along with the Fiber To The Home/Building/Curb (FTTX) traffic through the shared fiber. Finally, we present and analyze the simulation results for the aforementioned infrastructure based on our adopted priority-based FTTX-WSN integration model.

Hydrogen technology has widely been acknowledged as a route to reduced carbon emissions and energy security. However, it is also recognised that technology development alone is not enough to cause a shift change in uptake and that public perception also needs to be considered. This paper identifies the public perception of hydrogen technology (with specific interest in biologically produced hydrogen) and determines whether it meets the public expectation in terms of its potential energetic output. The energetic viability of hydrogen (defined for this purpose as a net positive energy balance) is derived by determining the potential for agriculturally produced hydrogen using dark fermentative production techniques. A suitable range of energy crops have been identified using selection criteria including yield, harvest window and composition of the crops. Public perception of hydrogen energy was investigated through the use of two focus groups. This identified Welsh public opinions on the production and end use of hydrogen energy. Due to the rapid progress in wireless communication technologies and the increasing demands for new services; cutting edge techniques and research have developed wireless access delivery of broadband data. Such systems referred to as Broadband Fixed Wireless Access Systems (BFWA) or alternatively, Local Multipoint Distribution Systems (LMDS), are increasingly being regarded as a legitimate challenger to cable and digital subscriber lines (DSL), particularly in markets with poor cable or copper infrastructure. These systems have capabilities that go beyond the current WiFi and WiMAX technologies by providing users with higher bandwidths and faster data rates. The frequency of operation for such networks lies between 28 and 42 GHz according to the spectrum bands allocated for future LMDS networks. The presented work aims at proposing a generalized stochastic model for the LMDS urban/suburban propagation channel. The model is based on a physical electromagnetic representation of the millimetre wavelength channel, with particular emphasis on fading margins in line-of-sight (LOS) links. The study focuses on the analysis, modelling and measurements of the fading effects of signal scattering caused by building surfaces and the ground on the direct field in an LMDS link at millimetre­ waves. Outcomes have been validated against experimental results obtained in realistic propagation scenarios. More than 180 field measurement sets were taken at 40 GHz for model testing and validation purposes. The main innovation of this work is the solution proposed to address the problem of signal scatter at millimetre-wave lengths. The approach uses high-frequency approximations to the analytical solution given by Kirchhoff s tangent-plane representation of rough surfaces. The electromagnetic field and signal power at the receiver are considered random and are evaluated using the Physical Optics method over different possible realizations of the surface geometry and building architectural features. This has resulted in novel derivations of the mean field, mean power density and scatter distribution of the scattered field. In comparison to deterministic models, such as ray-tracing that require intensive computations and detailed (millimetric resolution) knowledge of topographical data that are almost impossible to obtain, the proposed model is rather efficient and yields accurate results. The model has also been employed in analysing the effects of building scatter on the variance of the main desired link and the adjacent- or co-channel interfering link arising from neighbouring cells in cellular LMDS networks. This has enabled predictions of signal-to-interference ratio statistics and distributions for a particular underlying propagation environment. Overall, compansons yielded very good agreements between measurements and predictions of the main statistical parameters, thus verifying the main assumptions relating to the received signal strength, as well as the validity of a Rician distribution in describing the signal envelope variability for both the main and interference links in complex millimetre-wave propagation environments.

Broadband wireless access (BWA) network working at millimetre bands possesses the advantages of quick deployment, more flexibility, wide service coverage and cost efficiency. The range of services to be provided via the system includes broadband digital television, Internet data, telephony and videoconference. Apart from broadcast digital television, all traffic is carried in Internetworking Protocol (IP) format. Unfortunately the services of such a system are susceptible to impairment by buildings, vegetation, terrain and attenuation caused by rain, snow and sleet, etc. Accordingly the service availability and system performance can drop dramatically. In the worst case, the system will experience heavy packet loss and the services might be completely unavailable. An extended multiprotocol label switching (MPLS) network architecture is proposed in this thesis, which allows fast mobile IP access and diversity routing for traffic under fade condition. This supports nomadic access, reduced packet loss and improved service availability in BWA network during system outage. Also developed herein is a Diversity and Shadow Flow Merging Mechanism, which, besides sending a packet on its normal path, also duplicates the packet and sends it on a separate, diverted labelled path. The shadow flow merging mechanism is responsible for merging the normal flow and shadow flow together and delivering the merged packet to its destination. It is anticipated that the packet can be successfully delivered to the destination even if one path fails completely during the system outage. The protocol is tested on a general BWA network that is configured with Digital Video Broadcast (DVB) downlink and Multi-Frequency Time Division Multiplex Access (MF-TDMA) uplink equipments. The protocol’s ability of reducing packet loss and improving service availability, during the period of link failure, is verified. It is concluded that the protocol is effective in improving the service availability of BWA network.

Thesis (M.S. in Information Technology Management and M.S. in Computer Science)--Naval Postgraduate School, March 2004.
Thesis advisor(s): Burt Lundy. Includes bibliographical references (p. 99-100). Also available online.

Millions of Canadians residing in northern, isolated, rural and remote communities do not have broadband internet and this has led to a national 'broadband divide' induced by geography. The rollout of wired broadband is limited in rural and remote areas because of the high deployment and maintenance costs that would be passed onto the consumer who would be unwilling to pay exorbitant subscription fees. Alternatively, wireless broadband access does not entail the kind of physical infrastructure and associated costs which dramatically changes how broadband internet can be provided beyond the urban zone. This research develops a geographic information systems (GIS) model to determine if emerging terrestrial wireless broadband technologies (WiMAX) can effectively service the rural and remote regions of Canada. In addition, the robustness of the GIS model is tested in Alberta using intervisibility analyses at multiple spatial scales. Results suggest that coarse-scale GIS modelling with minimal data requirements can reliably identify potential wireless broadband markets. This research clearly shows that GIS modelling can make a significant contribution to the analysis of wireless deployment planning, to the understanding of the relationships between wireless signal sources and consumers, and to the spatial configuration of terrestrial wireless broadband networks.

Broadband Wireless Access technologies have significant market potential, especially the WiMAX protocol which can deliver data rates of tens of Mbps. Strong demand for high performance WiMAX solutions is forcing designers to seek help from multi-core processors that offer competitive advantages in terms of all performance metrics, such as speed, power and area. Through the provision of a degree of flexibility similar to that of a DSP and performance and power consumption advantages approaching that of an ASIC, coarse-grained dynamically reconfigurable processors are proving to be strong candidates for processing cores used in future high performance multi-core processor systems. This thesis investigates multi-core architectures with a newly emerging dynamically reconfigurable processor – RICA, targeting WiMAX physical layer applications. A novel master-slave multi-core architecture is proposed, using RICA processing cores. A SystemC based simulator, called MRPSIM, is devised to model this multi-core architecture. This simulator provides fast simulation speed and timing accuracy, offers flexible architectural options to configure the multi-core architecture, and enables the analysis and investigation of multi-core architectures. Meanwhile a profiling-driven mapping methodology is developed to partition the WiMAX application into multiple tasks as well as schedule and map these tasks onto the multi-core architecture, aiming to reduce the overall system execution time. Both the MRPSIM simulator and the mapping methodology are seamlessly integrated with the existing RICA tool flow. Based on the proposed master-slave multi-core architecture, a series of diverse homogeneous and heterogeneous multi-core solutions are designed for different fixed WiMAX physical layer profiles. Implemented in ANSI C and executed on the MRPSIM simulator, these multi-core solutions contain different numbers of cores, combine various memory architectures and task partitioning schemes, and deliver high throughputs at relatively low area costs. Meanwhile a design space exploration methodology is developed to search the design space for multi-core systems to find suitable solutions under certain system constraints. Finally, laying a foundation for future multithreading exploration on the proposed multi-core architecture, this thesis investigates the porting of a real-time operating system – Micro C/OS-II to a single RICA processor. A multitasking version of WiMAX is implemented on a single RICA processor with the operating system support.

FUNDAÇÃO DE APOIO À PESQUISA DO ESTADO DO RIO DE JANEIRO
O projeto de sistemas fixos de acesso sem fio em banda larga operando em ambientes abertos em frequências entre 10 e 66 GHz requer um planejamento criterioso devido à necessidade de maximizar a utilização da largura de banda disponível, maximizar a capacidade da rede, garantir requisitos mínimos de disponibilidade e minimizar os custos em um tipo de ambiente e em uma faixa de frequências em que as ondas eletromagnéticas são sujeitas a fenômenos específicos durante a propagação. Este trabalho apresenta os aspectos envolvidos no planejamento de sistemas deste tipo que utilizam topologia ponto-multiponto e atendem à recomendação IEEE 802.16. São apresentados modelos para previsão de cobertura, cálculo da atenuação diferencial por chuvas e previsão da atenuação por chuvas considerando a não-homogeneidade das chuvas em duas dimensões horizontalmente. Os efeitos das interferências no desempenho dos sistemas são analisados em conjunto com alguns exemplos de planejamento das células. Os aspectos importantes para o planejamento da capacidade são descritos e técnicas que permitem maximizar a capacidade são apresentadas. Com o objetivo de organizar todas as informações para ajudar em situações reais uma metodologia de planejamento é proposta incluindo considerações técnicas, mercadológicas e financeiras.
The development of outdoor fixed broadband wireless access (BWA) systems operating at 10-66 GHz frequency requires a carefully planning in order to maximizing the use of the bandwidth, maximizing network capacity, assuring minimum requirements of availability and minimizing costs in an environment and in a frequency band where the propagation of electromagnetic waves are subjected to specific issues. This work presents the aspects related to the development of this kind of system in a point-to- multipoint architecture standardized by the IEEE 802.16 recommendation. Models to predict coverage, estimate differential rain attenuation and predict rain attenuation considering the un-homogeneity of the rain in horizontal plane. The effects of interference in the system performance are discussed with some examples of cell planning. The main aspects of capacity planning are described and techniques to maximize capacity are presented. In order to helping the planners in practical situations the information are organized in a proposal of planning methodology that includes technical, business and marketing issues.

In today's knowledge-based economy, issues concerning equitable access to telecommunication services and their quality remain an important public policy focus. Wireline broadband Internet brings a significant expense of installation and maintenance, especially in less densely populated rural and remote areas. The rural, sparsely populated areas of southern Illinois are considered the broadband periphery and are underserved in terms of equitable access to high speed Internet. This study explores utilizing Geographic Information Systems (GIS) as a tool to identify relevant local obstructions ("clutter") in the development of a more reliable, cost effective metrics for the deployment of wireless towers. After performing extensive quality control on tower coordinates obtained from the Federal Communications Commission (FCC), which were only 47% accurate, a spatial model to represent and analyze wireless broadband infrastructure and demand in the twenty-one county southern Illinois study region was developed. The key factors extracted for wireless broadband propagation are the land cover surrounding the tower, elevation and slope of the terrain, and tower height. Geographically weighted regression analysis was used to determine typical characteristics of users of wireless technology, with income, age, and education having the most significant effect. According to Census data for the year 2000, 33,910 of the 174,959 households in southern Illinois have poor or no wireless coverage. Based on the results of the study and policy recommendations, wireless broadband technologies are viable solutions to help bridge the broadband gap in southern Illinois and rural America.

New generation wireless networks are designed not only to carry voice but also to support data-intensive and multimedia applications. Broadband wireless networks offer high bandwidth necessary to support these applications. However, without proper resource allocation schemes, increased bandwidth is not sufficient to meet diverse application quality of service (QoS) requirements. In designing or deploying a resource allocation scheme, it is crucial to understand the inter-relationship of the resource allocation scheme and important system parameters with resulting QoS performance. Analytical models provide an opportunity to derive these relationships in an accurate and readily verifiable way. In this thesis, we develop novel analytical models for radio resource allocation schemes in emerging broadband wireless access networks. These models are then adopted for in-depth analysis of QoS performance of the modeled schemes and in devising new solutions based on the models to either improve upon or complement those schemes. Our work primarily deals with Medium Access Control layer; however, in most of our contributions, we also consider cross-layer issues. First, we develop a queueing model for a downlink packet scheduling policy in IEEE 802.16e mobile broadband systems and propose a resource allocation framework based on this model. Compared to existing schemes, proposed framework offers a simple yet more effective way to provide QoS to a heterogeneous mix of applications. Second, we develop a cross-layer model for a prominent multiuser scheduling scheme in multi-antenna-based broadband cellular systems. It captures cross-layer effects of important parameters of the multi-antenna physical layer. The model output is shown to have important applications in QoS provisioning. Next, we perform queueing analysis of controlled channel access mechanism in IEEE 802.11e-based Wireless Local Area Networks. Using the insight gained, we propose a novel channel access scheduling mechanism that achieves very robust performance in meeting QoS guarantees. Finally, we focus on a promising new technology called Cognitive Radio (CR), which can greatly improve spectrum utilization in next generation broadband systems. We develop a queueing model to analyze the performance of an opportunistic spectrum access mechanism in CR networks. The model has important applications including cross-layer analysis and admission control in CR-based broadband networks.

Commutation signalling is an antimultipath technique employing direct-sequence bandwidth spreading for combatting multipath induced ISI. We propose a CDMA-like multiple-access scheme which utilizes this inherent spreading for broadband cellular indoor wireless communications. The intra-cell multiple-access is by time division while the inter-cell interference is reduced via combined frequency and code division. The frequency bands of adjacent cells overlap to increase bandwidth efficiency. We consider the interference between spread-spectrum signals with partially overlapping spectra and apply the results to the analysis of this cellular system. The uplink and downlink are considered with and without cell sectorization. The downlink is used for obtaining certain system design parameters and for comparing the merits of different pulse shapes. We finally compare the proposed scheme with the usual TDMA/FDMA and CDMA schemes. The proposed scheme is found to require less bandwidth compared to the usual TDMA/FDMA scheme. However, CDMA requires a lesser bandwidth than the proposed scheme since it employs powerful very low rate channel coding techniques.

The growth of broadband Internet access has paved the way for the development of many new technologies. As the cost of implementing broadband access soars, the best alternative will be to use fixed wireless for these services. This thesis addresses the possibility of 3rd Generation (3G) mobile cellular wireless systems as the basis for fixed broadband wireless service. Two of the 3G technologies aimed at providing fixed broadband wireless access are Time Division Synchronous Code Division Multiple Access (TD-SCDMA) and Orthogonal Frequency Division Multiplexing (OFDM).

This thesis aims to provide a preliminary study on using TD-SCDMA and OFDM for broadband wireless systems. Currently, there is not enough theory and information to establish the feasibility of using either of these technologies for broadband wireless access. First, the basic features and background on synchronous CDMA and OFDM are presented for the reader to better understand these technologies. Then, an example TD-SCDMA system is described, and some analytical and experimental results are presented. Finally, TD-SCDMAâ s technologies, along with this systemâ s attributes, are compared analytically to that of Vector OFDM (VOFDM).
Master of Science

Thesis (Ph.D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Gee-Kung Chang; Committee Co-Chair: Jianjun Yu; Committee Member: John A. Buck; Committee Member: Joy Laskar; Committee Member: Umakishore Ramachandran; Committee Member: Ye Li

Approved for public release; distribution is unlimited
Existing copper phone and cable infrastructure no longer provide the required broadband for today's emerging applications. Homes and businesses in the "last mile" require the same access to broadband speeds available inside the fiber optic ring. It is not economically feasible, however, to bring fiber optic cable to each and every home and business in the "last mile." Free Space Optics and Wireless Broadband Radio Frequency are two technologies gaining popularity as an alternative broadband infrastructure. Free Space Optics uses lasers and Wireless Broadband uses Radio Frequency waves to send large amounts of data from one place to another. Both are wireless technologies that use free space. As a result, they are quickly deployed, easily scaled, and cheaper to install and upgrade than wired infrastructures. These characteristics support missions of the Armed Forces in which wire-bound infrastructure is not dependable, is impractical to build and maintain, or requires a high degree of mobility. This thesis addresses the "last mile" problem including why current infrastructure will not provide a broadband solution. Free Space Optics and Wireless Broadband Radio Frequency technologies are explored and discussed. Finally, an economic analysis of alternative network designs utilizing the two emerging technologies is applied to a fictitious city with a population of one million.

Future generation cellular networks are expected to deliver an omnipresent broadband access network for an endlessly increasing number of subscribers. Long term Evolution (LTE) represents a significant milestone towards wireless networks known as 4G cellular networks. A key feature of LTE is the implementation of enhanced Radio Resource Management (RRM) mechanism to improve the system performance. The structure of LTE networks was simplified by diminishing the number of the nodes of the core network. Also, the design of the radio protocol architecture is quite unique. In order to achieve high data rate in LTE, 3rd Generation Partnership Project (3GPP) has selected Orthogonal Frequency Division Multiplexing (OFDM) as an appropriate scheme in terms of downlinks. However, the proper scheme for an uplink is the Single-Carrier Frequency Domain Multiple Access due to the peak-to-average-power-ratio (PAPR) constraint. LTE packet scheduling plays a primary role as part of RRM to improve the system’s data rate as well as supporting various QoS requirements of mobile services. The major function of the LTE packet scheduler is to assign Physical Resource Blocks (PRBs) to mobile User Equipment (UE). In our work, we formed a proposed packet scheduler algorithm. The proposed scheduler algorithm acts based on the number of UEs attached to the eNodeB. To evaluate the proposed scheduler algorithm, we assumed two different scenarios based on a number of UEs. When the number of UE is lower than the number of PRBs, the UEs with highest Channel Quality Indicator (CQI) will be assigned PRBs. Otherwise, the scheduler will assign PRBs based on a given proportional fairness metric. The eNodeB’s throughput is increased when the proposed algorithm was implemented.

First-generation, line-of-sight (LOS) fixed broadband wireless access techniques have been around for several years. However, services based on this technology have been limited in scope to service areas where transceivers can communicate with their base stations, unimpeded by trees, buildings and other obstructions. This limitation has serious consequences in that the system can deliver only 50% to 70% coverage within a given cell radius, thus affecting earned revenue. Next generation broadband fixed wireless access techniques are aimed at achieving a coverage area greater than 90%. To achieve this target, these techniques must be based on a point-to-multipoint (PMP) cellular architecture with low base station antennas, thus possessing the ability to operate in true non-line-of-sight (NLOS) conditions. A possible limiting factor for these systems is link degradation due to interference. This thesis presents a new model to estimate the levels of co-channel interference for such systems operating within the 3.5 GHz multichannel multipoint distribution service (MMDS) band. The model is site-specific in that it uses statistical building/roof height distribution parameters obtained from practically modeling several metropolitan cities in the U.S. using geographic information system (GIS) tools. This helps to obtain a realistic estimate and helps analyze the tradeoff between cell radius and modulation complexity. Together, these allow the system designer to decide on an optimal location for placement of customer premises equipment (CPE) within a given cell area.
Master of Science

This thesis presents an exploratory study into the development of digital societies and it examines public sector modernization and innovation from a technology management perspective. The study presents reasons why most city-wide or council-wide development of wireless broadband access networks currently end in failure or are unsustainable. It also suggests its links with wider problems of innovation management and the commercial failure of otherwise technically competent solutions It explores the modernisation of society, government, the underlying theories that influence it as well as the innovations triggered by its wake. The exercise reveals a myriad of innovations; firstly in the modernisation of the infrastructure of government and secondly in the development of societal infrastructure in the form of broadband networks.

This thesis presents an exploratory study into the development of digital societies and it examines public sector modernization and innovation from a technology management perspective. The study presents reasons why most city-wide or council-wide development of wireless broadband access networks currently end in failure or are unsustainable. It also suggests its links with wider problems of innovation management and the commercial failure of otherwise technically competent solutions It explores the modernisation of society, government, the underlying theories that influence it as well as the innovations triggered by its wake. The exercise reveals a myriad of innovations; firstly in the modernisation of the infrastructure of government and secondly in the development of societal infrastructure in the form of broadband networks.

More than a billion people access the Internet through residential broadband connections worldwide, and this number is projected to grow further. Surprisingly, little is known about some important properties of these networks: What performance do users obtain from their ISP? What factors affect performance of broadband networks? Are users bottlenecked by their ISP or by their home network? How are applications such as the Web affected by these factors? Answering these questions is difficult; there is tremendous diversity of technologies and applications in home and broadband networks. While a lot of research has tackled these questions piecemeal, the lack of a good vantage point to obtain good measurements from these networks makes it notably difficult to do a holistic characterization of the ﾓlast mileﾔ. In this dissertation we use the home gateway to characterize home and access networks and mitigate performance bottlenecks that are specific to such networks. The home gateway is uniquely situated; it is always on and, as the hub of the network, it can directly observe the home network, the access network, and user traffic. We present one such gateway- based platform, BISmark, that currently has nearly 200 active access points in over 20 countries. We do a holistic characterization of three important components of the last mile using the gateway as the vantage point: the access link that connects the user to the wider Internet, the home network to which devices connect, and Web performance, one of the most commonly used applications in today's Internet. We first describe the design, development, and deployment of the BISmark platform. BISmark uses custom gateways to enable measurements and evaluate performance opti- mizations directly from home networks. We characterize access link performance in the US using measurements from the gateway; we evaluate existing techniques and propose new techniques that help us understand these networks better. We show how access link technology and home networking hardware can affect performance. We then develop a new system that uses passive measurements at the gateway to localize bottlenecks to either the wireless network or the access link. We deploy this system in 64 homes worldwide and characterize the nature of bottlenecks, and the state of the wireless network in these homes - specifically we show how the wireless network is rarely the bottleneck as throughput exceeds 35 Mbits/s. Finally, we characterize bottlenecks that affect Web performance that are specific to the last mile. We show how latency in the last mile results in page load times stagnating at throughput exceeding 16 Mbits/s, and how simple techniques deployed at the gateway can mitigate these bottlenecks.

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.

碩士
國立臺灣大學
商學研究所
93
Industry Analysis and Co-opetition Strategy of Broadband Wireless Access(BWA) This study is to investigate BWA industry''s evolution process, analyze the industry structure, market situation, product technology and relative industry standard, and to find out industry''s competitive key successful factor and existence leader manufacturer''s Co-competition strategy. The study takes the advantage of industry analyses and relative theories as a research tool. "Structure - Behavior - Performance " Model theory is the main analytic framework, and bases on the element of 「Network Effect」、「Information product platform」、 「Supply Networks」 as a method to analyze Smart card industry structure. It also bases on the 「M.E. Poter Competitive Advantage Theories」 and 「Games theory & Co-competition strategy」to analyze participant''s Co-competition strategy in this industry landscape. Analyzing the information form the market and internet, referring to the relative industry experiences, and describing the Co-competition situation of BWA industry''s development process will be the experience reference for later comers in this industry. In conclusion, this research will provide the future development direction and several worthy research topics for Taiwan manufacturers.

碩士
國立臺灣大學
資訊管理學研究所
94
Recently, the incumbent service providers in broadband fixed access underserved the communities due to lack of demand and high-cost infrastructure. The possible remedy for the situation may need to adopt the broadband wireless access technology with licensed-exempt spectrum. This study analyzes the broadband wireless access industry and proposing the applicable business model and strategy for equipment vendors. After the analysis we found Wi-Mesh technology at the current stage is the best fit for BWA industry, for the long run this study will provide the future development direction and study areas for BWA vendors.