Dissertations / Theses on the topic 'Cellar management'

Thesis (MBA)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: The terms business model and business model innovation have only gained prominence over the past two decades, whilst little of the research has been applied in a South African context. The main objective of this thesis was to ascertain the reasons for success of a local business through the research and application of the themes of business models, business model innovation and blue ocean strategy to a local organisation. The subject matter of the thesis was Van Loveren Family Wine Cellar, a family-owned South African wine farm that has seen significant success over the past 15 years in a highly competitive and fragmented local market. To complete this process, it was also necessary to gain an understanding of both the global and local wine industries, and how South Africa has grown within this environment. The format of the thesis is a case study, selected because of its relevance to gaining a rich understanding of the context of the research and the processes enacted, thereby facilitating the main objectives. The case study approach also provides a tool to aid in the education of business strategy students, allowing the principles to be applied to new scenarios. The findings of the study include that there has been a shift in both consumption and production of wine from the traditional Old World to the innovative New World. This shift is being driven by new consumers of wine who are less concerned with the mystique and legacy of Old World wine, instead demanding wines that fit their lifestyles through easy drinking taste profiles with an ease of selection. This phenomenon is present in South Africa, where growth in the market is seen at lower price points. New consumers who are selecting wines that compete with existing alcohol alternatives as gateway products are driving this demand. Van Loveren launched their Four Cousins Rosé in 2000, with exponential growth experienced between 2004 and 2008, driving the product to be one of South Africa’s best-selling brands. The findings of the study were that the Van Loveren Family Cellar had positioned itself, through business model innovation, to capture the growth in new wine drinkers. Van Loveren had built a business model that provided a framework within which strategy can take on competitors. Core to their success were the long-term relationships with key buyers and the collaborative partnerships that allowed Van Loveren to utilise external capabilities as part of their own business. The success was also based on the leap of faith to enter the market in a sweeter taste profile, through the development of a brand that resonated with consumers, and in packaging that provided an attractive price point. The combination of these decisions allowed Van Loveren to capture uncontested market and grow exponentially.

Thesis (MBA)--Stellenbosch University, 2008.
ENGLISH ABSTRACT: The goal of this study was to investigate the feasibility of a small-scale biomass gasification system within the context of a cooperative wine cellar operation in the Western Cape of South Africa. Central to this goal was the questions whether the time for the implementation of such small-scale renewable energy technologies in South Africa has arrived, in light of the status quo which has changed drastically from the days of abundant and cheap coal-based electricity, and whether the new opportunities afforded by the CDM can help foster financial feasibility. There are various macro-drivers contributing to the current-day emphasis on renewable energy and cogeneration projects. The first and most pressing driver is the global climate change imperative, while the others include the increased aspiration of countries towards energy security, the realization of the importance of sustainable development and the subsequent renewable energy policies that falls within the ambit of sustainable development. Small-scale biomass gasification technology still poses some challenges, particularly when it comes to the gasification of agricultural residues, as with grape residues in the case of this project. The most important technical feasibility problem to overcome is the low ash agglomeration temperature of grape residues reported in the literature. Although the local equipment manufacturer foresees no problem in this regard with their system design - since they have conducted tests on sunflower seed residues, which have similar ash properties, without experiencing any agglomeration problems - the seriousness of this aspect will be confirmed during pilot trials. In order to be eligible for emissions reduction trading under the CDM, the project must adequately demonstrate that the emissions reductions are additional to the business-as-usual scenario, in both the environmental and financial sense. The project will satisfy the environmental additionality requirement, since in its absence the wine cellar will continue its full reliance on coal-based electricity from the grid. Financial additionality, in its strictest sense, requires for the project to be infeasible if it does not pursue CDM participation, which the financial feasibility modeling results indicated to be true in this case. A feasibility model was developed to - subject to the input parameter values assumed and basic assumptions made - be able to assess the financial viability of the project. The main assumptions were that the private feed-in into the national electricity grid was available to all IPPs, in spite of the fact that in its Medium Term Power Purchase Program me (MTPPP) of May 2008 Eskom had only requested expressions of interest from IPPs that had a generating capacity of 5MW and higher to install private base load capacity. This assumption is commensurate with the country's renewable energy targets and the official government aim of achieving a 30% contribution from IPPs to the national electricity mix. The second assumption was that the 65 to lOOclkWh offered by Eskom in its MTPPP will be applicable to sub-SMWe IPPs as well (Creamer, 2008), and that this lower bound electricity price of 65clkWh can be applied over the whole project lifetime. Inherent to this assumption is the further supposition that the progressive decline of electricity prices to an eventual level of 35clkWh by 2018 foreseen by Eskom will not materialize, due both to the sustained pressure an expanding South African economy will put on the considerable but time-consuming supply-side initiatives launched by Eskom, and the likelihood for price premiums to be introduced for clean electricity in order to meet the country's renewable energy targets. From the assumed input parameter values the initial capital and COM expenditures, operating revenues and costs over the project lifetime were determined, and then used to calculate the net cash flows, where after the NPV was computed to serve as the deciding criterion on financial feasibility. A discount rate of 18% was assumed, corresponding with the subjectively judged risks that the project posed as a small-scale renewable energy system within the wine cellar operations. In the case where the project excluded all CDM aspects, the NPV was negative at - ZAR342 573, but this improved to ZAR325 193 if the project participated in the CDM. Thus it was concluded that the project will only be financially feasible if it includes CDM participation, and that this positive contribution can be leveraged by pursuing a programmatic CDM approach. This entails the development of this project as part of a larger program in which similar projects are implemented as they arise, up to the official UN limit of 15MWe in total to still qualify as a small-scale program. The nature of the assumptions that form the backbone of this study indicate that the positive financial feasibility result in the case where the project includes COM participation will become practically relevant only over the short- to medium-term as these assumptions become reality in South Africa. Therefore, although the time for such small-scale renewable energy projects has clearly not arrived as yet, it would seem that it is indeed around the corner.
AFRIKAANSE OPSOMMING: Die mikpunt van die navorsing was om die lewensvatbaarheid van 'n klein-skaal biomassa vergassing sisteem binne die konteks van 'n kooperatiewe wynkelder in die Wes-Kaap van Suid-Afrika te ondersoek. 'n Sentrale aspek was die vrae of die tyd aangebreek het om klein-skaal volhouhare energie projekte in Suid-Afrika tot uitvoering te bring, gesien in die lig van 'n status quo wat drasties weg beweeg het van die tydperk toe elektrisiteit volop en goedkoop was, en of die geleentheid wat die CDM bied sulke projekte finansieel lewensvatbaar kan maak. Daar is verskeie eksterne makro-drywers wat bydrae tot die huidige fokus op sulke volhoubare energie projekte. Hieronder tel globale klimaatsverandering as die dringendste drywer, terwyl die res onder andere die hernuwe strewe van lande tot verbeterde energie-sekuriteit, die besef van die belangrikheid van volhoubare ontwikkeling en die daaropvolgende volhoubare energie beleid stappe insluit. Daar bestaan nog etlike tegniese uitdagings tot die toepassing van klein-skaal biomassa vergassing tegnologie, spesifiek met betrekking tot die vergassing van afval landbou byprodukte, soos wat die geval is met druiwe afval in hierdie projek. Die belangrikste tegniese uitvoerbaarheids-aspek wat aandag verg is die lae smeltpunt van druifafval-as wat in die literatuur rapporteer word. Alhoewel die plaaslike toerustings-vervaardiger nie enige probleme in hierdie verhand voorsien nie, aangesien toetse met sonneblom afval - met as-eienskappe rofweg identies aan die van druiwe-afval - geen smelting van die as getoon het nie, sal dit tog nogsteeds aan verdere toetse onderwerp word. Vir die projek om te kwalifiseer as geskik vir verhandeling in kweekhuisgas vermindering deur middel van die COM, moet dit voldoende bewys kan word dat alle uitlaatgas vermindering addisioneel is tot wat die geval sou wees in die gewone gang van besigheid. Hierdie addisionaliteit is relevant in beide 'n omgewings- en finansiele sin. Hierdie projek sal orngewings-addisionaliteit bevredig deurdat die wynkelder in sy afwesigheid volkome afhanklik van die steenkool-gebaseerde elektrisiteit vanaf die nasionale netwerk sou bly, terwyl finansiele addisionaliteit bewys is deur die finansiele lewensvatbaarheids-model wat getoon het dat die projek slegs ekonomies uitvoerbaar sal wees indien dit CDM deelname insluit. Die lewensvatbaarheids-model is ontwikkel om die ekonomiese uitvoerbaarheid van die projek te evalueer, onderworpe aan die aangenome inset parameter waardes en basiese aannames in die studie. Die hoof-aanname was naamlik dat privaat terugvoer in die nasionale elektrisiteits-netwerk vir alle grootte IPPs moontlik is, ten spyte van die feit dat Eskom se MTPPP van Mei 2008 slegs kapasiteite van 5MW en groter aanvaar bet. Hierdie aanname is gebaseer op Suid-Afrika se volhoubare energie teikens en die regering se offisiele mikpunt om 30% van alle krag-voorsiening vanaf IPPs te bekom. Die tweede hoof-aanname was dat die 65 tot 100clkWh wat Eskom in sy MTPPP aangebied het, ook van toepassing sal wees op sub-SMW IPPs (Creamer, 2008), en dat die laer prys-limiet van 65c/kWb oor die hele projek-leeftyd toegepas kon word. Inherent tot hierdie aanname is die verdere veronderstelling dat die progressiewe daling in elektrisiteits-pryse tot 'n eventuele vlak van 35clkWh voorsien deur Eskom nie sal realiseer nie, beide as gevolg van die volgehoue druk wat die groeiende Suid-Afrikaanse ekonomie op die aansieniike, maar tydrowende, opwekkings-kapasiteit uitbreidings van Eskom behoort te plaas, en ook die hoe waarskynlikheid dat prys premiums vir skoon elektrisiteit ingestel word sodat Suid-Afrika sy volboubare energie telkens kan bereik. Die aanvanklike kapitaal en CDM uitgawes, en bedryfsuitgawes en - inkomstes oor die projekleeftyd is vanaf die aangenome inset parameter waardes afgelei, waarop die NPV van die projek uitgewerk is om te dien as die beslissende maatstaf van ekonomiese haalbaarheid. 'n Diskontokoers van 18% is gebruik, ooreenstemmend met die subjektief beraamde risikos wat die projek inhou as 'n klein-skaal volhoubare energie sisteem. Die resultate van die finansiele lewensvatbaarheids-model het getoon dat in die geval waar die projek geen CDM aspekte bevat nie, die NPV hoogs negatief sou wees met 'n waarde van -ZAR342 573, terwyl dit verbeter na ZAR325 193 as die projek CDM deelname insluit. Die gevolgtrekking is dus gemaak dat die spesifieke projek slegs ekonomies haalbaar sal wees indien dit wel CDM deelname insluit, en dat hierdie positiewe finansiele bydrae van die CDM geoptimaliseer kan word deur 'n programmatiese CDM benadering te volg. Dit behels die ontwikkeling van die projek as deel van 'n groter program waarin soortgelyke projekte mettertyd geimplementeer word soos hulle ontstaan, tot by die offisiele VN limiet van 15MWe om sodoende nog te kwalifiseer as 'n algehele klein-skaalse program. Die aard van die hoof-aannames in hierdie studie is indikatief dat die positiewe finansiele lewensvatbaarheid in die geval waar die projek CDM deelname insluit, eers oor die kort- tot medium-termyn prakties relevant sal word soos die aannames bevredig word. Dus, alhoewel die era van klein-skaalse volhoubare energie projekte nog nie aangebreek het in Suid-Afrika nie, lyk dit tog asof dit om die draai is.

This master’s thesis deals with the selection and implementation of an information system for the Pavlovín winery s.r.o. In this thesis is firstly introduces the theoretical foundation necessary for the understanding of this topic and subsequently is analysed the current state of the company with an emphasis on the information system and production processes related to process procedures in the field of cellar management. The penultimate part of the thesis is connected with the evaluation of the information system variant and the subsequent selection of the optimal variant, its implementation is described in the last chapter using the technique of project management.

Thesis (MBA)--Stellenbosch University, 2002.
ENGLISH ABSTRACT: This mini-study project examines the strategic position of the Douglas Wine Cellar in context with the dynamics in the wine industry. For success in the future it suggests that producers, manufactures and marketing strategies will have to focus on doing the same things differently as well as doing different things, with the emphasis on improving productivity, increasing quality focus and generating value-added products aimed at meeting market requirements. The greater focus on productivity in agriculture should include wider use of effective farming practices, more effective use of capital equipment, more effective implementation of Research & Development results, product differentiation and brand building as well as the development of distribution channels with the ability to deliver these products in a cost effective and timely manner. There is no single "Superhighway". Routes are complex and discontinuous with an ever increasing pace of change. Today we live and work in a technology rich society. Rapid advancements in all industries are occurring daily. To survive and prosper, Douglas Wine Cellar must commit to a continual processof advancement and improvement of strategies to fulfill the vision of GWKLtd. THE VISION OF GWK IS TO BE A SUSTAINABLE AGRI-BUSINESS OF EXCELLENCE
AFRIKAANSE OPSOMMING: Hierdie werkstuk is onderneem ten einde die strategiese posisie van Douglas Wynkelder in die konteks van die wynindustrie dinamika te ondersoek. Sukses in die toekoms hang daarvan af of produsente, vervaardigers en bemarkingstrategië daarop fokus om dieselfde dinge verskillend te doen sowel as om nuwe stelsels te implementeer, met die klem op produktiwiteit, verhoogde kwaliteit en die generering van waardetoegevoegde produkte wat aan die markbehoeftesvoldoen. Die groter fokus op produktiwiteit in die landbou behoort die algemene verbruik van effektiewe boerderypraktyke, effektiewe kapitaalspandering, effektiewe implementering van navorsings- & ontwikkelingsresultate, produkdifferensiasie en handelsmerk-uitbouing in te sluit, asook die ontwikkeling van distribusiekanale met die vermoë om produkte koste effektief en tydig aan die mark te lewer. Daar bestaan geen enkele "super hoofweg" nie. Roetes is kompleks en nie volhoubaar nie, met ewigdurende veranderings. Vandag lewe en werk ons in 'n tegnologies-ontwikkelde samelewing. Vinnige vooruitgang in alle industrië is aan die orde van die dag. Om te oorleef en welvaart te skep moet Douglas Wynkelder die pad betree van voortdurende vordering en verbetering van strategië, om sodoende aan die visie van GWK Bpk te voldoen. DIE VISIE VAN GWK IS OM IN VOLHOUBARE LANDBOUBESIGHEID VAN UITNEMENDHEID TE WEES

In wireless networks, there is an ever-increasing demand for higher system throughputs, along with growing expectation for all users to be available to multimedia and Internet services. This is especially difficult to maintain at the cell-edge. Therefore, a key challenge for future orthogonal frequency division multiple access (OFDMA)-based networks is inter-cell interference coordination (ICIC). With full frequency reuse, small inter-site distances (ISDs), and heterogeneous architectures, coping with co-channel interference (CCI) in such networks has become paramount. Further, the needs for more energy efficient, or “green,” technologies is growing. In this light, Uplink Interference Protection (ULIP), a technique to combat CCI via power reduction, is investigated. By reducing the transmit power on a subset of resource blocks (RBs), the uplink interference to neighbouring cells can be controlled. Utilisation of existing reference signals limits additional signalling. Furthermore, cell-edge performance can be significantly improved through a priority class scheduler, enhancing the throughput fairness of the system. Finally, analytic derivations reveal ULIP guarantees enhanced energy efficiency for all mobile stations (MSs), with the added benefit that overall system throughput gains are also achievable. Following this, a novel scheduler that enhances both network spectral and energy efficiency is proposed. In order to facilitate the application of Pareto optimal power control (POPC) in cellular networks, a simple feasibility condition based on path gains and signal-to-noise-plus- interference ratio (SINR) targets is derived. Power Control Scheduling (PCS) maximises the number of concurrently transmitting MSs and minimises their transmit powers. In addition, cell/link removal is extended to OFDMA operation. Subsequently, an SINR variation technique, Power SINR Scheduling (PSS), is employed in femto-cell networks where full bandwidth users prohibit orthogonal resource allocation. Extensive simulation results show substantial gains in system throughput and energy efficiency over conventional power control schemes. Finally, the evolution of future systems to heterogeneous networks (HetNets), and the consequently enhanced network management difficulties necessitate the need for a distributed and autonomous ICIC approach. Using a fuzzy logic system, locally available information is utilised to allocate time-frequency resources and transmit powers such that requested rates are satisfied. An empirical investigation indicates close-to-optimal system performance at significantly reduced complexity (and signalling). Additionally, base station (BS) reference signals are appropriated to provide autonomous cell association amongst multiple co-located BSs. Detailed analytical signal modelling of the femto-cell and macro/pico-cell layouts reveal high correlation to experimentally gathered statistics. Further, superior performance to benchmarks in terms of system throughput, energy efficiency, availability and fairness indicate enormous potential for future wireless networks.

Manter e ampliar relacionamentos com clientes, na área de serviços, é estimular a retenção de clientes e, consequentemente, fazer com que as empresas passem a ser vistas de forma diferenciada pelo mercado. Entretanto, as empresas prestadoras de serviços devem compreender o processo que envolve os clientes nos encontros de serviços, investigando os construtos que implicam na captação e na retenção dos mesmos, para que sejam desenvolvidas estratégias adequadas. Sendo assim, esta pesquisa propôs a replicação e testagem de um Modelo Teórico, considerando os construtos Valor Percebido, Reputação do Provedor de Serviços, Confiança e Custos de Troca como determinantes da Retenção de Clientes. Desenvolveu-se, então, a construção teórica acerca da Retenção de Clientes e dos demais construtos contemplados nesta pesquisa, com a intenção de compreender e analisar a atuação dos mesmos no relacionamento entre clientes e prestadores de serviços, bem como suas relações com as estratégias competitivas das empresas. Dando sequência ao estudo, foi realizada a pesquisa quantitativa, por meio da aplicação de uma survey. Para a análise dos dados, foram utilizadas estatísticas multivariadas, incluindo a Modelagem de Equações Estruturais, para que fossem testadas e analisadas as hipóteses levantadas pelo estudo aqui proposto. Os resultados evidenciaram que: o valor percebido pelos clientes influencia positivamente a reputação do provedor de serviços; o valor percebido pelos clientes não influencia positivamente os custos de troca; a reputação do provedor de serviços influencia positivamente a confiança do cliente no provedor de serviços; a reputação do provedor de serviços não influencia positivamente os custos de troca; a confiança depositada pelo cliente em relação ao provedor de serviços influencia positivamente a retenção de clientes; os custos de troca não influenciam positivamente a retenção de clientes; e a reputação do provedor de serviços influencia positivamente a retenção de clientes.
Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2015-04-01T17:00:54Z No. of bitstreams: 1 Dissertacao Daniele Nespolo.pdf: 1700635 bytes, checksum: f523232449b286777b973826707eb6dd (MD5)
Made available in DSpace on 2015-04-01T17:00:54Z (GMT). No. of bitstreams: 1 Dissertacao Daniele Nespolo.pdf: 1700635 bytes, checksum: f523232449b286777b973826707eb6dd (MD5)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, CAPES.
Maintaining and expanding relationships with customers in the service area, is to encourage customer retention and thus cause the corporation to be viewed differently by the market. However, the service providers must understand the process involving customers in service encounters, investigating the constructs involving the capture and retention of the same, so that appropriate strategies can be developed. Thus, this research has proposed replication and testing a theoretical model, considering the constructs Perceived Value, Reputation of Service Provider, Reliability and Cost of Exchange as determinants of Customer Retention. Developed the theoretical construction about Customer Retention and others constructs included in this study, with the intent to understand and analyze the performance of the same in the relationship between clients and service providers, as well as its relations with the competitive strategies of firms. Giving sequence to the study, was realized a quantitative research by the application of a survey. For data analysis, multivariate statistics, including Structural Equation Modeling, to be tested and analyzed the hypotheses proposed by the study presented here. The results showed that: perceived value positively influences the reputation of the service provider; perceived value by customers not positively influences switching costs; the reputation of the service provider positively influences customer trust in the provider; the reputation of the service provider not positively influences the switching costs; the trust placed by the customer in relation to the provider positively influences customer retention; the switching costs not positively influences customer retention; and the reputation of the service provider positively influences customer retention.

COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
Nos últimos anos, considerável debate tem ocorrido a respeito do tema gerência de mobilidade, face à necessidade de se fazer uso judicioso dos recursos de sinalização destinados para esse fim no âmbito de sistemas de comunicação móvel celular e de sistemas de comunicação pessoal (PCS). Dentre as estratégias de gerência de mobilidade, destaca-se a utilização do conceito de áreas de registro, amplamente empregadas a partir dos sistemas de 2a. geração, e permitindo reduzir o consumo de recursos devido a atualizações de localização. Outro conceito, o de áreas de paging, tem também se tornado bastante difundido, propiciando a economia de recursos gastos na procura de terminais móveis por ocasião de tentativas de completamento de chamadas para estes terminais. Este trabalho inicia-se com discussão a respeito de modelos de mobilidade empregados no estudo de problemas e técnicas da área de comunicações móveis. Dentre tais modelos, destacam- se no contexto do trabalho o modelo baseado em fluxo de fluídos e o modelo gravitacional. O problema de particionamento em áreas de localização (LAPP) é então tratado como um problema de particionamento de grafos, cuja elevada complexidade enseja a utilização de heurísticas capazes de propiciar a obtenção de soluções próximas da ótima. As heurísticas propostas destinam-se ao caso mais comum, em que áreas de localização são coincidentes com áreas de paging. Com base em metodologia utilizada para o LAPP, são propostas soluções para um outro problema, o ISHMP (Inter-Switch Handover Minimization Problem), cuja importância se prende não só ao elevado consumo de recursos mas também aos atrasos impostos pelo sistema aos usuários quando estes trocam de área de Mobile Switching Center. Assim, reduzir ao máximo a ocorrência de tais eventos é vantajoso tanto do ponto de vista do usuário quanto do sistema. As heurísticas propostas são essencialmente as mesmas para ambos os problemas, e mostram superioridade em termos de qualidade das soluções obtidas quando comparadas com propostas de outros autores, através de casos-padrão publicados na literatura e de testbed construído especialmente para a comparação. Apresenta-se ainda discussão a respeito de modelos de mobilidade empregados no estudo de problemas e técnicas da área de comunicações móveis. Dentre tais modelos, destacam- se o modelo baseado em fluxo de fluidos e o modelo gravitacional. O trabalho apresenta também estudo relativo às cargas de sinalização que ocorrem tnato na rede fixa (incluindo o tráfego de consultas e atualizações sobre as bases de dados) quanto na interface aérea. No apêndice, considerando o grafo que modela a rede celular, apresenta-se comprovação formal da conversão de pesos de nós e de arestas em novos pesos de arestas, permitindo o tratamento dos dois problemas de particionamento aqui abordados como problemas de edgepartitioning puros.
In the past few years there hás been considerable debate over the question of mobility management in móbile cellular communication networks, due to the need of using the signaling system resources in a careful way. Among the strategies of location management, the utilization of registration areas has been difunded since the emergence of the second generation mobile communication systems, allowing to reduce the resource consumption due to location updates. Another concept, named paging areas, has also been extensively employed, allowing to save resources utilized localization of mobile terminals during the call setup for mobile stations. Initially, the Location Area Partitioning Problem (LAPP) is treated as a graph partitioning problem, largely recognized as NP-complete ([GARE 79], [LENG 90]) and leading to the utilization of heuristics, able to produce good sub-optimal solutions. The heuristics are proposed to solve the more usual case, where location areas are coincident with paging areas, and the frequency spectrum (radio resources). With the same methodology, another problem, named Inter- Switch Handover Minimization Problem (ISHMP), is adequately solved, being its relevance due to the elevated system resource consumption and to the severe delays imposed to users when their Mobile Switching Centers are changed. Thus, the diminution of the occurrence of such events id advantageous from both the user`s and the system`s points of view. The heuristics are eddentially the same for the two problems, and it is shown the superiority of the quality of the quality of the obtained solutions, when comparing them with other published results. The work also presents discussion about mobility models employed in the study of problems and techniques in the mobile communications area. Among such models, the fluid flow and the gravitational models are highlighted. A study concerning to the signaling load imposed to the fixed network (including queries and location update traffic over databases) and to the air interface is presented. Finally, starting from the average rate of mobile terminated calls and from a previously defined user impatience threshold, a new proposal for the definition of the optimal number of cells per paging area is presented.

The rapid growth in the mobile users of cellular networks has brought big challenges for the networks and their providers in tackling the coverage extension and capacity boosting. The Heterogeneous Networks (HetNets) is considered as one of the best solutions to meet the ever increasing data rate and coverage demands. The HetNets consists of the deployment of smaller base stations (known as small cells) overlaying the traditional macrocells. Indeed, small cells can cover some areas where it is not possible to be covered by the macrocells. Despite the potential benefits of deploying small cells along with the traditional macrocell, the ultra-dense deployment brought the concerns of interference and mobility management. As a result of mobility, users will have to perform handover between base stations to maintain service continuity. However, the ultra-dense small cells will cause a huge number of frequent handovers resulting in many issues including high signalling overhead, handover failures, unbalanced load distribution and high energy consumption. Unfortunately, these issues will limit the benefits of deploying small cells. In summary, the purpose of this thesis is to investigate the existing literature works and then propose techniques to address the problems mentioned above in HetNets. Firstly, a handover technique is proposed to reduce the number of target small cells for the user and to minimize the unnecessary handovers in the HetNets which eventually enhances the overall quality of service delivered to the end user. Then, we considered both of the unnecessary handover and handover failure where the number of target small cells is also reduced by considering interference, predicted time that a user may stay in the coverage area of a small cell and the small cell capacity. Additionally, a novel handover technique is proposed to improve the throughput and load balancing is proposed where an offloading strategy, by forcing the handover considering the load and interference, is considered to derive a handover margin. The margin is then used to perform the handover to the target base station. Moreover, the multiple attribute decision making principle is used to model the handover problem in HetNets and to address the user energy efficiency. First, we propose a handover mechanism to minimize the unnecessary handover and radio link failure, in addition to enhancing the throughput. This is obtained by deploying multiple attribute decision making weighted methods, Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS), in which selected handover parameters are weighted to evaluate their importance prior to the handover process. Second, a user-energy efficient handover mechanism is investigated via multiple attributes decision making weighted strategy, Grey Rational Analysis (GRA), which accounts for the minimization of the unnecessary handover and radio link failure, in addition to enhancing the user experience in terms of reducing its power consumption. Finally, a game theory framework is used to manage the handover problem in terms of energy efficiency. First, we propose a novel handover method for energy efficiency in HetNets where a game theory approach is used to manage the transmission power of the base stations by reducing/halting the transmission power for light-loaded base stations prior to the handover process. The game is solved mathematically using the principle of coarse correlated equilibrium. The Regret Matching-based Learning is deployed to learn the equilibrium in this game. Second, a non-cooperative game approach is formulated where base stations behave selfishly to obtain higher gain. The payoff function is defined to consider the gain from increasing the base station transmission power (the utility function) against the cost resulted from energy consumption, base station load and unnecessary handovers performed to this base station. In order to solve the game, we proved the existence of at least one Nash equilibrium.

La prolifération d'applications et de services sophistiqués s'accompagne de diverses exigences de performances, ainsi que d'une croissance exponentielle du trafic pour le lien montant (uplink) et descendant (downlink). Les réseaux cellulaires tels que 4G et 5G évoluent pour prendre en charge cette quantité diversifiée et énorme de données. Le travail de cette thèse vise le renforcement de techniques avancées de gestion et supervision des réseaux cellulaires prenant l'explosion du trafic et sa diversité comme deux des principaux défis dans ces réseaux. La première contribution aborde l'intégration de l'intelligence dans les réseaux cellulaires via l'estimation du débit instantané sur le lien montant pour de petites granularités temporelles. Un banc d'essai 4G temps réel est déployé dans ce but de fournir un benchmark exhaustif des métriques de l'eNB. Des estimations précises sont ainsi obtenues. La deuxième contribution renforce le découpage 5G en temps réel au niveau des ressources radio dans un système multicellulaire. Pour cela, deux modèles d'optimisation ont été proposés. Du fait de leurs temps d'exécution trop long, des heuristiques ont été développées et évaluées en comparaisons des modèles optimaux. Les résultats sont prometteurs, les deux heuristiques renforçant fortement le découpage du RAN en temps réel
The proliferation of sophisticated applications and services comes with diverse performance requirements as well as an exponential traffic growth for both upload and download. The cellular networks such as 4G and 5G are advocated to support this diverse and huge amount of data. This thesis work targets the enforcement of advanced cellular network supervision and management techniques taking the traffic explosion and diversity as two main challenges in these networks. The first contribution tackles the intelligence integration in cellular networks through the estimation of users uplink instantaneous throughput at small time granularities. A real time 4G testbed is deployed for such aim with an exhaustive metrics benchmark. Accurate estimations are achieved.The second contribution enforces the real time 5G slicing from radio resources perspective in a multi-cell system. For that, two exact optimization models are proposed. Due to their high convergence time, heuristics are developed and evaluated with the optimal models. Results are promising, as two heuristics are highly enforcing the real time RAN slicing

The thesis focuses on the provision of cellular vehicle-to-everything (V2X) communications, which have attracted great interest for 5G due to the potential of improving traffic safety and enabling new services related to intelligent transportation systems. These types of services have strict requirements on reliability, access availability, and end-to-end (E2E) latency. V2X requires advanced network management techniques that must be developed based on the characteristics of the networks and traffic requirements. The integration of the Sidelink (SL), which enables the direct communication between vehicles (i.e., vehicle-to-vehicle (V2V)) without passing through the base station into cellular networks is a promising solution for enhancing the performance of V2X in cellular systems. In this thesis, we addressed some of the challenges arising from the integration of V2V communication in cellular systems and validated the potential of this technology by providing appropriate resource management solutions. Our main contributions have been in the context of radio access network slicing, mode selection, and radio resource allocation mechanisms. With regard to the first research direction that focuses on the RAN slicing management, a novel strategy based on offline Q-learning and softmax decision-making has been proposed as an enhanced solution to determine the adequate split of resources between a slice for eMBB communications and a slice for V2X. Then, starting from the outcome of the off-line Q-learning algorithm, a low-complexity heuristic strategy has been proposed to achieve further improvements in the use of resources. The proposed solution has been compared against proportional and fixed reference schemes. The extensive performance assessment have revealed the ability of the proposed algorithms to improve network performance compared to the reference schemes, especially in terms of resource utilization, throughput, latency and outage probability. Regarding the second research direction that focuses on the mode selection, two different mode selection solutions referred to as MSSB and MS-RBRS strategies have been proposed for V2V communication over a cellular network. The MSSB strategy decides when it is appropriate to use one or the other mode, i.e. sidelink or cellular, for the involved vehicles, taking into account the quality of the links between V2V users, the available resources, and the network traffic load situation. Moreover, the MS-RBRS strategy not only selects the appropriate mode of operation but also decides efficiently the amount of resources needed by V2V links in each mode and allows reusing RBs between different SL users while guaranteeing the minimum signal to interference requirements. The conducted simulations have revealed that the MS-RBRS and MSSB strategies are beneficial in terms of throughput, radio resource utilization, outage probability and latency under different offered loads comparing to the reference scheme. Last, we have focused on the resource allocation problem including jointly mode selection and radio resource scheduling. For the mode selection, a novel mode selection has been presented to decide when it is appropriate to select sidelink mode and use a distributed approach for radio resource allocation or cellular mode and use a centralized radio resource allocation. It takes into account three aspects: the quality of the links between V2V users, the available resources, and the latency. As for the radio resource allocation, the proposed approach includes a distributed radio resource allocation for sidelink mode and a centralized radio resource allocation for cellular mode. The proposed strategy supports dynamic assignments by allowing transmission over mini-slots. A simulation-based analysis has shown that the proposed strategies improved the network performance in terms of latency of V2V services, packet success rate and resource utilization under different network loads.
La tesis se centra en la provisión de comunicaciones para vehículos sistemas celulares (V2X: Vehicle to Everything), que han atraído un gran interés en el contexto de 5G debido a su potencial de mejorar la seguridad del tráfico y habilitar nuevos servicios relacionados con los sistemas inteligentes de transporte. Estos tipos de servicios tienen requisitos estrictos en términos fiabilidad, disponibilidad de acceso y latencia de extremo a extremo (E2E). Para ello, V2X requiere técnicas avanzadas de gestión de red que deben desarrollarse en función de las características de las redes y los requisitos de tráfico. La integración del Sidelink (SL), que permite la comunicación directa entre vehículos (es decir, vehículo a vehículo (V2V)) sin pasar por la estación base de las redes celulares, es una solución prometedora para mejorar el rendimiento de V2X en el sistema celular. En esta tesis, abordamos algunos de los desafíos derivados de la integración de la comunicación V2V en los sistemas celulares y validamos el potencial de esta tecnología al proporcionar soluciones de gestión de recursos adecuadas. Nuestras principales contribuciones han sido en el contexto del denominado "slicing" de redes de acceso radio, la selección de modo y los mecanismos de asignación de recursos radio. Respecto a la primera dirección de investigación que se centra en la gestión del RAN slicing, se ha propuesto una estrategia novedosa basada en Q-learning y toma de decisiones softmax como una solución para determinar la división adecuada de recursos entre un slice para comunicaciones eMBB y un slice para V2X. Luego, a partir del resultado del algoritmo de Q-learning, se ha propuesto una estrategia heurística de baja complejidad para lograr mejoras adicionales en el uso de los recursos. La solución propuesta se ha comparado con esquemas de referencia proporcionales y fijos. La evaluación ha revelado la capacidad de los algoritmos propuestos para mejorar el rendimiento de la red en comparación con los esquemas de referencia, especialmente en términos de utilización de recursos, rendimiento, y latencia . Con respecto a la segunda dirección de investigación que se centra en la selección de modo, se han propuesto dos soluciones de diferentes llamadas estrategias MSSB y MS-RBRS para la comunicación V2V a través de una red celular. La estrategia MSSB decide cuándo es apropiado usar el modo SL o el modo celular, para los vehículos involucrados, teniendo en cuenta la calidad de los enlaces entre los usuarios de V2V, los recursos disponibles y la situación de carga de tráfico de la red. Además, la estrategia MS-RBRS no solo selecciona el modo de operación apropiado, sino que también decide eficientemente la cantidad de recursos que los enlaces V2V necesitan en cada modo, y permite que los RB se reutilicen entre diferentes usuarios de SL al tiempo que garantiza requisitos mínimos de señal a interferencia. Se ha presentado un análisis basado en simulación para evaluar el desempeño de las estrategias propuestas. Finalmente, nos hemos centrado en el problema conjunto de la selección de modo y la asignación de recursos de radio. Para la selección de modo, se ha presentado una nueva estrategia para decidir cuándo es apropiado seleccionar el modo SL y usar un enfoque distribuido para la asignación de recursos de radio o el modo celular y usar la asignación de recursos de radio centralizada. Tiene en cuenta tres aspectos: la calidad de los enlaces entre los usuarios de V2V, los recursos disponibles y la latencia. En términos de asignación de recursos de radio, el enfoque propuesto incluye una asignación de recursos de radio distribuida para el modo SL y una asignación de recursos de radio centralizada para el modo celular. La estrategia propuesta admite asignaciones dinámicas al permitir la transmisión a través de mini-slots. Los resultados muestran las mejoras en términos de latencia, tasa de recepción y la utilización de recursos bajo diferentes cargas de red.

Interference management is one of the most challenging problems facing wireless communication networks, especially for the cellular wireless communication system that is based on reuse-one deployment. This problem becomes even more noteworthy in the heterogeneous cellular networks (HetNets) where lower power nodes (LPNs) are deployed in the coverage area of the macro base station (MBS). The higher transmit power possessed by the MBS, together with the cell selection procedure employed in HetNet: where a user equipment (UE) may be served by a closer LPN (to enable cell splitting) even though the received power from the MBS could be higher, are some factors that cause interference in HetNet. In the 5th generation mobile networks (5G) when the number of deployed LPNs increases interference will be more serious. This thesis proposes interference management techniques based on beamforming with different level of cooperation amongst base stations in HetNet. In this thesis, we first designed global beamforming vectors that will maximize the weighted sum-rate of HetNet while fulfilling some power and interference constraints. The interference constraint controls the allowable interference from the MBS to other UEs in the HetNet. The global beamforming vectors were achieved using the Branch and Bound technique which is a global optimization method used in solving non-convex optimization problems. The beamformers that maximize the weighted sum-rate of HetNet are designed jointly by all BSs in the HetNet, hence the implementation is done centrally. Since each UE in HetNet has peculiar interference situation, we design a UE-centric clustering scheme, which is capable of determining the BSs in the HetNet that interferes each UE the most at a particular time. Afterward, these BSs coordinate interference with the serving BS of this UE and make resource allocation decisions together to allocate beamforming directions and powers to each UE in the HetNet. This will spatially separate signals sent to each UE, thereby mitigating interference and improving the total data rate achievable in HetNet. HetNet tends to be distributed, also X2-interface which is the backhaul link that connects BSs in the HetNet has a limited capacity which makes it incapable of withstanding huge burdens in its backhaul. We, therefore, design distributed beamforming directions using only local channel state information available at each transmitter. We also develop optimal power allocation scheme for each UE in each cell to maximize the sum-rate of each cell in the HetNet.

Abstract Radio resource management techniques for broadband wireless systems beyond the existing cellular systems are developed while considering their special characteristics such as multi-carrier techniques, adaptive radio links and multiple-input multiple-output (MIMO) antenna techniques. Special focus is put on the design of linear transmission strategies in a cooperative cellular system where signal processing can be performed in a centralised manner across distributed base station (BS) antenna heads. A time-division duplex cellular system based on orthogonal frequency division multiplexing (OFDM) with adaptive MIMO transmission is considered in the case where the received signals are corrupted by non-reciprocal inter-cell interference. A bandwidth efficient closed-loop compensation algorithm combined with interference suppression at the receiver is proposed to compensate for the interference and to guarantee the desired Quality of Service (QoS) when the interference structure is known solely at the receiver. A greedy beam ordering and selection algorithm is proposed to maximise the sum rate of a multiuser MIMO downlink (DL) with a block zero forcing (ZF) transmission. The performance of the block-ZF transmission combined with the greedy scheduling is shown to approach the sum capacity as the number of users increases. The maximum sum rate is often found to be achieved by transmitting to a smaller number of users or beams than the spatial dimensions allow. In addition, a low complexity algorithm for joint user, bit and power allocation with a low signalling overhead is proposed. Different linear transmission schemes, including the ZF as a special case, are developed for the scenario where the cooperative processing of the transmitted signal is applied to users located within a soft handover (SHO) region. The considered optimisation criteria include minimum power beamformer design; balancing the weighted signal-to-interference-plus-noise ratio (SINR) values per data stream; weighted sum rate maximisation; and balancing the weighted rate per user with additional QoS constraints such as guaranteed bit rate per user. The method can accommodate supplementary constraints, e.g., per antenna or per BS power constraints, and upper/lower bounds for the SINR values of the data streams. The proposed iterative algorithms are shown to provide powerful solutions for difficult non-convex transceiver optimisation problems. System level evaluation is performed in order to assess the impact of a realistic multi-cell environment on the performance of a cellular MIMO-OFDM system. The users located in the SHO region are shown to benefit from greatly increased transmission rates. Consequently, significant overall system level gains result from cooperative SHO processing. The proposed SHO scheme can be used for providing a more evenly distributed service over the entire cellular network.

Proteins have to be folded to their native structures to be functionally expressed. Misfolded proteins are proteotoxic and negatively impact on cellular fitness. To maintain the proteome functional proteins are under the constant surveillance of dedicated molecular chaperones that perform protein quality control (PQC). Using the model organism yeast Saccharomyces cerevisiae this thesis investigates the molecular mechanisms that cells employ to maintain protein homeostasis (proteostasis). In Study I the role of the molecular chaperone Hsp110 in the disentanglement and reactivation of aggregated proteins was investigated. We found that Hsp110 is essential for cellular protein disaggregation driven by the molecular chaperones Hsp40, Hsp70 and Hsp104 and characterized its involvement via regulation of Hsp70 ATPase activity as a nucleotide exchange factor. In Study II we found out that Hsp110 undergoes translational frameshifting during its expression resulting in a nuclear targeting. Nuclear Hsp110 interacts with Hsp70 and reprograms the proteostasis system to better deal with stress and to confer longevity. Study III describes regulation of Hsp70 function in PQC by the nucleotide exchange factor Fes1. We found that rare alternative splicing regulates Fes1 subcellular localization in the cytosol and nucleus and that the cytosolic isoform has a key role in PQC. In Study IV we have revealed the molecular mechanism that Fes1 employ in PQC. We show that Fes1 carries a specialized release domain (RD) that ensures the efficient release of protein substrates from Hsp70, explaining how Fes1 maintains the Hsp70-chaperone system clear of persistent misfolded proteins. In Study V we report on the use of a novel bioluminescent reporter (Nanoluc) for use in yeast to measure the gene expression and protein levels. In summary, this thesis contributes to the molecular understanding of chaperone-dependent PQC mechanisms both at the level of individual components as well as how they interact to ensure proteostasis.

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 4: Manuscript.

As mobile phones get increasingly complicated the demands for an effective firmware update service increase. A proposed solution is Firmware Over The Air (FOTA) and the Open Mobile Alliance’s Device Management where mobile phones can be updated and managed via the mobile phone network. However, before these operations can be carried out, all FOTA capable mobile phones that should be served must be discovered and registered with a distributor of updates. The information provided must be sufficient to uniquely identify devices, initiate a Device Management session, and determine if a firmware update is needed. This thesis addresses the problems that a solution in automatically collecting this information. Several solutions are presented and their suitability evaluated on the basis of defined and analyzed requirements. The solutions most thoroughly examined are various manual solutions, retrieval of information from core network nodes, and utilizing the Short Message Service (SMS) or Unstructured Supplementary Service Data (USSD). A phone application has been implemented according to the requirements from the Chinese network operator China Mobile Communications Corporation (CMCC). It is a part of a solution in which the information is delivered via a SMS session. The design and development phase of the application is described, accompanied by a brief description of the Symbian OS and the working environment (tools, devices, etc.) needed to implement this solution. This work took place at the Sony Ericsson office in Beijing, China. The application implemented is robust and it is impossible to avoid registration, furthermore the user can not be exposed to acknowledgement messages. It has been made possible on the cost of decreased phone performance (a few kB of memory) since the application runs all the time. Malfunctioning phone or network may hinder registration.
Mobiltelefoner blir ständigt mer komplicerade vilket medför att efterfrågan av en effektiv lösning för uppdateringar av mjukvaran i mobiltelefonerna ökar. Lösningen är Firmware Over The Air (FOTA) och Device Management; mobiltelefonerna uppdateras och sköts via mobiltelefonnätverket. Men innan förfaranden kan exekveras måste alla mobiltelefoner med FOTA som ska omfattas av tjänsten upptäckas och registreras hos den som distribuerar uppdateringarna. Den information som måste levereras måste vara tillräcklig för att kunna identifiera mobiltelefonen, genomföra en Device Management session och avgöra om en uppdatering av mjukvaran är nödvändig. Detta examensarbete behandlar de problem som en lösning i vilken information tillhandahålls möter. Ett flertal lösningar presenteras och deras lämplighet utvärderas på basis av definierade och analyserade krav. De mest ingående undersökta lösningarna är olika manuella lösningar, insamling av information från noderna av kärnnätverket samt utnyttjande av SMS eller USSD. En telefonapplikation har implementeras enligt krav från den kinesiska operatören CMCC. Applikationen är en del av en lösning i vilken informationen levereras via en SMS-session. Applikationens design och utvecklingsfasen är beskriven, samt en översiktlig beskrivning av Symbian operativsystem och utvecklingsmiljön (verktyg, mobiltelefoner, etc.) som behövdes för att implementera lösningen. Detta arbete genomfördes på Sony Ericssons kontor i Beijing, Kina.

The demand for mobile wireless network resources is constantly on the rise, pushing for new communication technologies that are able to support unprecedented rates. In this thesis we address the issue by considering advanced interference management techniques to exploit the available resources more efficiently under relaxed channel state information (CSI) assumptions. While the initial studies focus on current half-duplex (HD) technology, we then move on to full-duplex (FD) communication due to its inherent potential to improve spectral efficiency. Work in this thesis is divided into four main parts as follows. In the first part, we focus on the two-cell two-user-per-cell interference broadcast channel (IBC) and consider the use of topological interference management (TIM) to manage inter-cell interference in an alternating connectivity scenario. Within this context we derive novel outer bounds on the achievable degrees of freedom (DoF) for different system configurations, namely, single-input single-output (SISO), multiple-input single-output (MISO) and multiple-input multiple-output (MIMO) systems. Additionally, we propose new transmission schemes based on joint coding across states that exploit global topological information at the transmitter to increase achievable DoF. Results show that when a single state has a probability of occurrence equal to one, the derived bounds are tight with up to a twofold increase in achievable DoF for the best case scenario. Additionally, when all alternating connectivity states are equiprobable: the SISO system gains 11/16 DoF, achieving 96:4% of the derived outer bound; while the MISO/MIMO scenario has a gain of 1/2 DoF, achieving the outer bound itself. In the second part, we consider a general G-cell K-user-per-cell MIMO IBC and analyse the performance of linear interference alignment (IA) under imperfect CSI. Having imperfect channel knowledge impacts the effectiveness of the IA beamformers, and leads to a significant amount of residual leakage interference. Understanding the extent of this impact is a fundamental step towards obtaining a performance characterisation that is more relevant to practical scenarios. The CSI error model used is highly versatile, allowing the error to be treated either as a function of the signal-to-noise ratio (SNR) or as independent of it. Based on this error model, we derive a novel upper bound on the asymptotic mean sum rate loss and quantify the DoF loss due to imperfect CSI. Furthermore, we propose a new version of the maximum signal-to-interference plus noise ratio (Max-SINR) algorithm which takes into account statistical knowledge of the CSI error in order to improve performance over the naive counterpart in the presence of CSI mismatch. In the third part, we shift our attention to FD systems and consider weighted sum rate (WSR) maximisation for multi-user multi-cell networks where FD base-stations (BSs) communicate with HD downlink (DL) and uplink (UL) users. Since WSR problems are non-convex we transform them into weighted minimum mean squared error (WMMSE) ones that are proven to converge. Our analysis is first carried out for perfect CSI and then expanded to cater for imperfect CSI under two types of error models, namely, a norm-bounded error model and a stochastic error model. Additionally, we propose an algorithm that maximises the total DL rate subject to each UL user achieving a desired target rate. Results show that the use of FD BSs provides significant gains in achievable rate over the use of HD BSs, with a gain of 1:92 for the best case scenario under perfect CSI. They also demonstrate the robust performance of the imperfect CSI designs, and confirm that FD outperforms HD even under CSI mismatch conditions. Finally, the fourth part considers the use of linear IA to manage interference in a multi-user multi-cell network with FD BSs and HD users under imperfect CSI. The number of interference links present in such a system is considerably greater than that present in the HD network counterpart; thus, understanding the impact of residual leakage interference on performance is even more important for FD enabled networks. Using the same generalised CSI error model from the second part, we study the performance of IA by characterising the sum rate and DoF losses incurred due to imperfect CSI. Additionally, we propose two novel IA algorithms applicable to this network; the first one is based on minimising the mean squared error (MMSE), while the second is based on Max-SINR. The proposed algorithms exploit statistical knowledge of the CSI error variance in order to improve performance. Moreover, they are shown to be equivalent under certain conditions, even though the MMSE based one has lower computational complexity. Furthermore for the multi-cell case, we also derive the proper condition for IA feasibility.

The limited bandwidth available for cellular networks has necessitated on current wireless technologies, such as long-term evolution (LTE), to devise new strategies to improve the spectrum reuse and the capacity of cellular networks. Multi-tier heterogeneous networks is a low-cost solution in which the traditional macrocells are underlaid with small cells such as femto- and pico- cells that are centered around users to improve the network capacity. In this regard, radio resource management (RRM) based interference avoidance techniques have been widely used to minimize the interference incurred as a result of small cell deployment. This thesis proposes novel interference management techniques for improving the spectrum reuse efficiency in cellular networks. An RRM that utilizes a sleep mode (SL) strategy is proposed to identify the small cells that maximize the reuse efficiency outcome when set to sleep mode without requiring an exhaustive search. To improve the association of the switched off cells users and improve the overall performance, an interference aware user association technique that allows seamless association between BSs and users is introduced to increase access to resources. To enhance both the overall throughput and quality of service (QoS) metrics, a map of the various interference levels is constructed to be used for two purposes: First to satisfy QoS constrains by orthogonalizing certain interfering BSs/users, and second to maximize the resource utilization using an adaptive power control scheme. To reduce the signaling overhead on the back-haul network, a distributed RRM is presented to allow BSs to independently adjust their bandwidth usage to reduce the inter-cell interference. With the lack of central management and coordination among cells, this information is estimated locally by monitoring the uplink spectrum.

Future mobile communications systems will be designed to support a wide range of data rates with complex and conflicting quality of service requirements. It is becoming more challenging to optimize radio resource management and maximise the system capacity whilst meeting the required quality of service from users' point of view. Traditional techniques have approached this problem by mainly focusing on resources within a cell and to large extent ignoring effects of multi-cell architecture leading to non uniform and unstable capacity across the network. This thesis first investigates the potential performance improvements obtained by developing novel distributed scheduling algorithms thereby highlighting the shortcomings of conventional single-cell scheduling techniques in a multi-cell system. It was found that distributed scheduling can achieve superior performance (up to 30% increased cell throughput) compared to conventional one in low/medium system loading. However, there is little advantage in case of heavily loaded system. The main achievement in this thesis is addressing this problem by proposal of a novel technique called Load Matrix, setting a new direction for future research on resource scheduling strategies in a multi-cell system. LM facilitates joint management of interference within and between cells for efficient allocation of radio resources. Simulation results provided show significant improvement in the resource utilization and overall network performance. Using LM technique, the average cell throughput can be increased between 30% to 50%. Results also show that maintaining cell interference within a margin as opposed to a hard target, can significantly improve resource utilization over time (longevity) and over the cells (uniformity). The thesis also compares the effect of ideal LM with practical and implementable versions with channel gain errors, information delay, and reducing LM database to adjacent cells. The conclusion was interesting as the performance degradation in practical LM compared to ideal LM was found to be negligible.

In this study, a dynamic resource management and subscriber profile prediction scheme for mobile communication systems is presented. The aim is to achieve a high level of QoS for both handoff calls and new calls, while at the same time to improve the utilization of wireless network resources. The simultaneous satisfaction of these two actually conflicting interests will be thanks to two major key features. First, it will be due to the individual subscriber profile based prior information about handoff reservation requests that are provided by the mobile terminals. This information is based on the cell transition probabilities calculated by the mobile itself using collected information during past operations. Second, it will be due to a two-way approach implemented in the resource management processes. The two-way approach controls both the amount of reserved radio channels and the new call admission in a dynamic way, depending on the subscriber mobility and network traffic conditions.

A novel radio resource management (RRM) scheme, which jointly considers the system characteristics from the physical, link and network layers, is proposed for cellular code division multiple access (CDMA) systems. Specifically, the power distribution at the physical layer distributes only the necessary amount of power to each connection in order to achieve its required signal-to-interference-plus-noise ratio (SINR). The rate allocation guarantees the required delay/jitter for real-time traffic and the minimum transmission rate requirement for non-real-time traffic. Efficient rate allocation is achieved by making use of the randomness and burstiness of the packet generation process. At the link layer, a packet scheduling scheme is developed based on the information of power distribution and rate allocation from the physical layer to achieve guaranteed quality of service (QoS). It schedules the system resource on a time slot basis to efficiently utilize the system resource in every time slot and to improve the packet throughput for non-real-time traffic. A connection admission control (CAC) scheme based on the lower layer resource allocation information is proposed at the network layer. The CAC scheme also makes use of user mobility information to reduce handoff connection dropping probability (HCDP). Theoretical analysis of the grade of service (GOS) performance, in terms of new connection blocking probability (NCBP), HCDP, and resource utilization, is given. Numerical results show that the proposed RRM scheme can achieve both effective QoS guarantee and efficient resource utilization.

Thesis (Ph.D.) - University of Waterloo, 2002.
"A thesis presented to the University of Waterloo in fulfilment of the thesis requirement for the degree of Doctor of Philosophy in Electrical and Computer Engineering". Includes bibliographical references. Also available in microfiche format.

The envisioned rapid and exponential increase of wireless data traffic demand in the next years imposes rethinking current cellular networks due to the available spectrum scarcity. In this regard, 3 main drivers are considered to increase the capacity of today's most advanced (4G) and future (5G and beyond) cellular networks: use more bandwidth (more Hz) through spectral aggregation, enhance the spectral efficiency per base station (BS) (more bits/s/Hz/BS) by using multi-antenna (i.e. MIMO) systems, and increase the density of BSs (more BSs/km2) through a dense and heterogeneous deployment. We focus on the last 2 drivers. First, the use of MIMO systems allows exploiting the spatial dimension for improving the capacity of a conventional point-to-point link, increasing the number of served users, and reducing unwanted emissions (interference). Second, dense heterogeneous networks are a simple and cost-effective way to boost the area spectral efficiency by densifying the network and improving the spatial re-use of the spectrum. However, increasing the BSs density entails two main technical challenges: the interference increases because neighboring BSs/users are nearer and the amount of data traffic, as well as downlink (DL) and uplink (UL) traffic asymmetry, varies over space and time more drastically since the number of users per BS is reduced. The increase of interference makes the development of efficient interference management techniques a key enabler for MIMO dense heterogeneous networks. On the other hand, the variability of the per-BS traffic amount and the DL/UL traffic asymmetry convert flexible duplexing (i.e. flexible allocation of DL/UL resources per BS) into a necessity for an efficient resource usage. Therefore, the development of resource management schemes capable of adapting to the varying traffic load, as well as interference management, becomes crucial. Accordingly, this thesis focuses on the development of advanced interference management techniques to deal with inter-cell interference in MIMO dense networks and on the design of traffic- and interference-aware resource management schemes for flexible duplexing systems in asymmetric traffic conditions. To these goals, the wide deployment of MIMO systems is capitalized to develop advanced multi-antenna signal processing techniques when full reuse of time and frequency resources among densely deployed BSs is adopted. In the first part, different statistical characterizations of the transmitted signals are analyzed to improve the capacity of wireless interference-limited MIMO channels. Advanced signaling schemes are developed and the use of improper Gaussian signaling (IGS) is investigated, which allows exploiting the real and imaginary dimensions of MIMO channels. Majorization theory is exploited to demonstrate the strict superiority of IGS. In the second part, transmit coordination strategies are proposed to manage interference in extremely dense cellular networks. The design of BSs transmit strategies (involving design of spatial transmit/receive filters, power control, and user scheduling) is coordinated to optimize different network functions while reducing the stringent requirements needed for channel estimation in dense networks. Coordination strategies for the case in which different signaling schemes coexist in the network are also derived. Further, coordination strategies for cluster-based joint transmissions are developed, where BSs are grouped into clusters and different clusters interfere to each other. The third part focuses on the design of traffic- and interference-aware duplexing techniques to make a better use of the available resources by taking into account the asymmetric traffic conditions that arise in dense networks and managing the new kinds of interference that come up under flexible duplexing. Short-term and long-term optimizations are investigated, being therefore the interference managed instantaneously and statistically, respectively.
L'augment ràpid i exponencial previst per a la demanda de tràfic de dades en els pròxims anys imposa redissenyar les xarxes cel·lulars actuals degut a l'escassetat de l'espectre radioelèctric disponible. Es consideren 3 eixos directors per augmentar la capacitat dels sistemes més avançats d'avui dia (4G) i del futur (5G i més enllà): utilitzar més ample de banda (més Hz), millorar l'eficiència espectral per estació base (BS) (més bits/s/Hz/BS) utilitzant sistemes multi-antena (MIMO) i incrementar la densitat de BSs (més BSs/km2) a través d'un desplegament dens i heterogeni. Ens centrem en els 2 últims eixos. En primer lloc, l'ús de sistemes MIMO permet explotar la dimensió espacial per millorar la capacitat d'un enllaç convencional punt a punt, incrementar el nombre d'usuaris servits i reduir emissions indesitjades (interferències). En segon lloc, les xarxes denses i heterogènies són una manera simple i rentable de millorar l'eficiència espectral per àrea a través de la densificació de la xarxa i la reutilització espacial de l'espectre. No obstant això, l'increment de la densitat de BSs planteja dos principals reptes tècnics: les interferències augmenten perquè BSs/usuaris veïns estan més propers i la quantitat de tràfic de dades, així com l'asimetria del tràfic de baixada (DL) i de pujada (UL), fluctua amb el temps i l'espai més dràsticament ja que el nombre d'usuaris per BS és reduït. Per tant, un factor clau per a les xarxes MIMO denses i heterogènies és el desenvolupament de tècniques eficients de gestió d'interferències. D'altra banda, la variabilitat de la quantitat i asimetria del tràfic converteix en una necessitat el duplexat flexible (és a dir, assignacions flexibles de recursos DL/UL per BS) per aconseguir un ús eficient dels recursos. Així doncs, es torna crucial el desenvolupament d'esquemes de gestió de recursos capaços d'adaptar-se a càrregues de tràfic variable i, a la vegada, gestionar interferències. Aquesta tesi es centra en el desenvolupament de tècniques avançades de gestió d'interferències per combatre interferències entre cel·les en xarxes MIMO denses i en el disseny d'esquemes de gestió de recursos que tenen en compte el tràfic i la interferència per a sistemes de duplexat flexible en condicions asimètriques de tràfic. Per aconseguir aquests objectius, s'aprofita l'ampli desplegament de sistemes MIMO per desenvolupar tècniques avançades de processament de senyals quan s'adopta reutilització completa de recursos entre BSs densament desplegades. En la primera part, s'analitzen diferents caracteritzacions estadístiques dels senyals transmesos per millorar la capacitat dels canals limitats per interferència. Es deriven esquemes de senyalització avançats i s'investiga l'ús de la senyalització Gaussiana improper, la qual permet explotar les dimensions reals i imaginàries dels canals MIMO. En la segona part, es proposen estratègies de transmissió coordinades per gestionar interferències en xarxes denses. El disseny de les estratègies de transmissió a les BSs (incloent: disseny de filtres espacials en transmissió/recepció, control de potència i selecció d'usuaris) és coordinat per optimitzar diferents funcions de xarxa mentre que es redueixen els estrictes requisits d'estimació de canal en xarxes denses. També s'analitzen estratègies de coordinació per al cas en què diferents esquemes de senyalització coexisteixen. A més, es deriven estratègies de coordinació per a transmissions conjuntes basades en grups, on les BSs s'agrupen en grups i grups veïns s'interfereixen entre si. La tercera part es centra en el disseny de tècniques de duplexat flexible que tenen en compte tràfic i interferència per fer un millor ús dels recursos disponibles, considerant condicions de tràfic asimètriques i gestionant els nous tipus d'interferències que apareixen sota el duplexat flexible. S'investiguen optimitzacions a curt i a llarg termini, sent llavors la interferència gestionada instantàniament i estadísticament, respectivament.
El aumento rápido y exponencial previsto para la demanda de tráfico de datos en los próximos años impone rediseñar las redes celulares inalámbricas actuales debido a la escasez del espectro radioeléctrico disponible. En este sentido, se consideran tres ejes directores para aumentar la capacidad de las redes celulares más avanzadas de hoy en día (sistemas 4G) y las del futuro (sistemas 5G y más allá): - utilizar más ancho de banda (más Hz) a través de la agregación de espectro, - mejorar la eficiencia espectral por estación base (BS) (más bits/s/Hz/BS) utilizando múltiples antenas en las BSs y los usuarios (sistemas MIMO), e - incrementar la densidad de BSs (más BSs/km2) mediante un despliegue denso y heterogéneo (conocido como redes densas y heterogéneas). Esta tesis se centra en los dos últimos ejes directores. En primer lugar, el uso de sistemas multi-antena permite explotar la dimensión espacial con varias finalidades: mejorar la capacidad de un enlace inalámbrico convencional punto a punto, incrementar el número de usuarios servidos y reducir emisiones indeseadas (interferencias). En segundo lugar, las redes densas y heterogéneas son una manera simple y rentable de mejorar la eficiencia espectral por área a través de la densificación de la red con BSs de diferentes características y de la reutilización espacial del espectro radioeléctrico. Sin embargo, el incremento de la densidad de BSs plantea dos principales desafíos técnicos: - las interferencias en la red aumentan porque BSs/usuarios vecinos están más próximos y - la cantidad de tráfico de datos, así como la asimetría del tráfico de bajada (DL) y de subida (UL), fluctúa con el tiempo y el espacio más drásticamente debido a que el número de usuarios por BS se reduce. El aumento de interferencias en la red hace que un factor clave para las redes MIMO densas y heterogéneas sea el desarrollo de técnicas eficientes de gestión de interferencias. Pero, a medida que avanzamos hacia redes más densas, la gestión de interferencias se convierte cada vez en un reto más desafiante. Por otro lado, la variabilidad de la cantidad de tráfico de datos por BS y de la asimetría del tráfico DL/UL convierten en una necesidad el duplexado flexible (es decir, asignaciones flexibles y dinámicas de recursos DL/UL por BS, ya sea en el dominio temporal o frecuencial) para conseguir un uso eficiente de los recursos radio que satisfaga las cargas de tráfico no uniformes en espacio y variantes en tiempo. Por lo tanto, se vuelve crucial el desarrollo de esquemas de gestión de recursos capaces de adaptarse a cargas de tráfico variable y de, a su vez, gestionar las interferencias. En este sentido, esta tesis doctoral se centra en: 1. el desarrollo de técnicas avanzadas de gestión de interferencias para hacer frente a las interferencias entre celdas en redes celulares MIMO densas, y 2. el diseño de esquemas de gestión de recursos que tengan en cuenta el tráfico y la interferencia para sistemas de duplexado flexible bajo condiciones de tráfico asimétricas. Para alcanzar estos objetivos, se aprovecha el amplio despliegue de sistemas MIMO con el fin de desarrollar técnicas multi-antena avanzadas de procesado de señales cuando se adopta un reúso completo de los recursos en tiempo y en frecuencia entre BSs densamente desplegadas en la red. En la primera parte de la tesis, se analizan diferentes caracterizaciones estadísticas de las señales de transmisión para mejorar la capacidad de los canales inalámbricos interferentes. En este sentido, se desarrollan esquemas de señalización avanzados y se investiga el uso de la señalización Gaussiana improper (IGS), la cual permite aprovechar las dimensiones reales e imaginarias de los canales de propagación MIMO mediante la división de una dimensión espacial en dos mitades. La teoría de la majorización se explota para demostrar la superioridad estricta de IGS. Después, los beneficios de IGS se aplican a diferentes escenarios MIMO limitados por interferencia. Otra forma de gestionar la interferencia con reúso completo de los recursos frecuenciales es mediante la coordinación y/o cooperación de BSs. La coordinación entre BSs permite ajustar de manera coordinada las estrategias de transmisión de diferentes BSs con el objetivo de reducir el impacto de las interferencias en la red. Por el contrario, la cooperación entre BSs permite que las BSs actúen como un único transmisor multi-antena y tiene la gran ventaja de que convierte la interferencia en señal útil a través de la transmisión conjunta de BSs cooperativas hacia un mismo usuario. Sin embargo, la cooperación requiere sincronización estricta y alta capacidad de backhaul para compartir datos de usuario entre BSs. Por esta razón, en implementaciones prácticas, la cooperación sólo se puede lograr entre un número reducido de BSs (las cuales forman un grupo) y la coordinación entre grupos sigue siendo necesaria para hacer frente a las interferencias. Tanto la coordinación como la cooperación, ya sean implementadas de forma centralizada o descentralizada, requieren el conocimiento de todos los canales de propagación de la red, lo cual impone requisitos estrictos en cuanto a estimación de canal para la gestión de interferencias en redes densas. En la segunda parte de este trabajo se proponen estrategias de transmisión coordinadas para gestionar interferencias en las redes celulares extremadamente densas. El foco está en la transmisión DL. El diseño de las estrategias de transmisión en las BSs (incluyendo el diseño de los filtros espaciales de transmisión y recepción, el control de potencia y la selección de usuarios) es coordinado con tal de optimizar diferentes funciones de red (como, por ejemplo, la suma ponderada de las tasas de transmisión), mientras que se reducen los estrictos requisitos necesarios para estimación de canal en redes densas. También se analizan estrategias de coordinación para el caso en que diferentes esquemas de señalización (proper e improper) coexisten en la red. Además, la tesis deriva estrategias de coordinación para transmisiones conjuntas basadas en grupos, donde las BSs se agrupan en grupos formados por un número reducido de BSs cooperativas y grupos vecinos se interfieren entre sí. En este caso, la estrategia de transmisión se optimiza conjuntamente con la formación de los grupos. Por último, se aborda la gestión de recursos en sistemas de duplexado flexible, donde los recursos tienen que ser distribuidos adecuadamente entre las transmisiones DL y UL de acuerdo con las asimetrías y la cantidad de tráfico de cada BS. Bajo una reutilización de recursos en BSs densamente desplegadas, el uso del duplexado flexible conlleva cambios en la interferencia generada entre BSs y/o usuarios vecinos. Como consecuencia, surgen nuevos tipos de interferencias (como la interferencia de BS a BS). La tercera parte de la tesis se centra en el diseño de técnicas de duplexado flexible que tienen en cuenta el tráfico para la gestión de recursos y de interferencias. En contraste con las partes anteriores, se consideran transmisiones DL y UL para cada BS. El objetivo principal es hacer un mejor uso de los recursos tiempo/frecuencia disponible, teniendo en cuenta las condiciones de tráfico asimétricas que surgen en redes densas, así como la gestión de los nuevos tipos de interferencias que aparecen bajo sistemas de duplexado flexible. Se investigan optimizaciones a corto plazo y a largo plazo, siendo entonces la interferencia gestionada de manera instantánea y de manera estadística, respectivamente.

There is a prolific increase in the penetration of user devices such as smartphones and tablets. In addition, user expectations for higher Quality of Service (QoS), enhanced data rates and lower latencies are relentless. In this context, network densification through the dense deployment of small cell networks, underlaying the currently existing macrocell networks, is the most appealing approach to handle the aforementioned requirements. Small cell networks are capable of reusing the spectrum locally and providing most of the capacity while macrocell networks provide a blanket coverage for mobile user equipment (UEs). However, such setup imposes a lot of issues, among which, co-tier and cross-tier interference are the most challenging. To handle co-tier interference, I have proposed a semi-distributed (hierarchical) interference management scheme based on joint clustering and resource allocation (RA) for small cells. I have formulated the problem as a Mixed Integer Non-Linear Program (MINLP), whose solution was obtained by dividing the problem into two sub-problems, where the related tasks were shared between the Femto Gateway (FGW) and small cells. As for cross-tier interference, I have formulated RA problems for both the macrocell and small cells as optimization problems. In particular, I have introduced the idea of ``Tier-Awareness'' and studied the impact of the different RA policies in the macrocell tier on the small cells performance. I have shown that the RA policy in one tier should be carefully selected. In addition, I have formulated the RA problem for small cells as an optimization problem with an objective function that accounts for both RA and admission control (AC). Finally, I have studied cloud radio access network (C-RAN) of small cells which has been considered as a typical realization of a mobile network which is capable of supporting soft and green technologies in Fifth Generation (5G) networks, as well as a platform for the practical implementation of network multiple-input multiple-output (MIMO) and coordinated multi-point (CoMP) transmission concepts.
February 2016

La qualité de communication dans un réseau sans fil est déterminée par la qualité du signal, et plus précisément par le rapport signal à interférence et bruit. Cela pousse chaque récepteur à se connecter à l'émetteur qui lui donne la meilleure qualité du signal. Nous utilisons la géométrie stochastique et la théorie des extrêmes pour obtenir la distribution de la meilleure qualité du signal, ainsi que celles de interférence et du maximum des puissances reçues. Nous mettons en évidence comment la singularité de la fonction d'affaiblissement modifie leurs comportements. Nous nous intéressons ensuite au comportement temporel des signaux radios en étudiant le franchissement de seuils par un processus stationnaire X (t). Nous démontrons que l'intervalle de temps que X (t) passe au-dessus d'un seuil γ → −∞ suit une distribution exponentielle, et obtenons 'egalement des r'esultats caract'erisant des franchissements par X (t) de plusieurs seuils adjacents. Ces r'esultats sont ensuite appliqu'es 'a la gestion de mobilit'e dans les r'eseaux cellulaires. Notre travail se concentre sur la fonction de 'handover measurement'. Nous identifions la meilleure cellule voisine lors d'un handover. Cette fonction joue un rôle central sur expérience perçue par l'utilisateur. Mais elle demande une coopération entre divers mécanismes de contrôle et reste une question difficile. Nous traitons ce problème en proposant des approches analytiques pour les réseaux émergents de types macro et pico cellulaires, ainsi qu'une approche d'auto- optimisation pour les listes de voisinage utilisées dans les réseaux cellulaires actuels.

Device-to-Device (D2D) communication has become a promising candidate for future wireless communication systems to improve the system spectral efficiency, while reducing the latency and energy consumption of individual communication. With the assistance of cellular network, D2D communications can greatly reduce the transmit distance by utilizing the spatial dispersive nature of ever increasing user devices. Further, substantial spectrum reuse gain can be achieved due to the short transmit distance of D2D communication. It, however, significantly complicates the resource management and performance analysis of D2D communication underlaid cellular networks. Despite an increasing amount of academic attention and industrial interests, how to evaluate the system performance advantages of D2D communications with resource management remains largely unknown. On account of the proximity requirement of D2D communication, the resource management of D2D communication generally consists of admission access control and resource allocation. Resource allocation of cellular assisted D2D communications is very challenging when frequency reuse is considered among multiple D2D pairs within a cell, as intense inter D2D interference is difficult to tackle and generally causes extremely large amount of signaling overheads for channel state information (CSI) acquisition. Hence, the first part of this thesis is devoted to the resource allocation of cellular assisted D2D communication and the performance analysis. A novel resource allocation scheme for cellular assisted D2D communication is developed with low signaling overhead, while maintaining high spectral efficiency. By utilizing the spatial dispersive nature of D2D pairs, a geography-based sub-cell division strategy is proposed to group the D2D pairs into multiple disjoint clusters, and sub-cell resource allocation is performed independently for the D2D pairs within each sub-cell without the need of any prior knowledge of inter D2D interference. Under the proposed resource allocation scheme, tractable approximation for the inter D2D interference modeling is obtained and a computationally efficient expression for the average ergodic sum capacity of the cell is derived. The expression further allows us to obtain the optimal number of sub-cells that maximizes the average ergodic sum capacity of the cell. It is shown that with small CSI feedback, the system capacity/spectral efficiency can be improved significantly by adopting the proposed resource allocation scheme, especially in dense D2D deployment scenario. The investigation of use cases for cellular assisted D2D communication is another important topic which has direct effect on the performance evaluation of D2D communication. Thanks to the spatial dispersive nature of devices, D2D communication can be utilized to harvest the vast amount of the idle computation power and storage space distributed at the devices, which yields sufficient capacities for performing computation-intensive and latency-critical tasks. Therefore, the second part of this thesis focuses on the D2D communication assisted Mobile Edge Computing (MEC) network. The admission access control of D2D communication is determined by both disciplines of mobile computing and wireless communications. Specifically, the energy minimization problem in D2D assisted MEC networks is addressed with the latency constraint of each individual task and the computing resource constraint of each computing entity. The energy minimization problem is formed as a two-stage optimization problem. At the first stage, an initial feasibility problem is formed to maximize the number of executed tasks, and the global energy minimization problem is tackled in the second stage while maintaining the maximum number of executed tasks. Both of the optimization problems in two stages are NP-hard, therefore a low-complexity algorithm is developed for the initial feasibility problem with a supplementary algorithm further proposed for energy minimization. Simulation results demonstrate the near-optimal performance of the proposed algorithms and the fact that the number of executed tasks is greatly increased and the energy consumption per executed task is significantly reduced with the assistance of D2D communication in MEC networks, especially in dense user scenario.

Les réseaux actuels et la prochaine génération des réseaux sans fil cellulaires (5G) doivent garantir, non seulement, les communications entre les gens (aussi connu sous le nom d'humain à humain - H2H), mais aussi à un déploiement massif de communication de type machine (MTC). MTC, ou encore Machine à Machine (M2M), peut être considérée comme des appareils qui peuvent établir des communications avec d’autres appareils sans aucune intervention humaine. M2M est aussi vue comme la pierre angulaire de la vision des objets connectés (IoT). Elle attire beaucoup d'attention, car elle peut être considérée comme une nouvelle opportunité pour les opérateurs de réseau et service IoT. Il existe aujourd’hui plusieurs types d’applications se basant sur MTC couvrant plusieurs domaines. On peut citer comme exemples les applications suivantes: la santé, les systèmes de transport intelligents (ITS), les compteurs intelligents et les réseaux intelligents, et la sécurité publique (PS). Le déploiement de ce type d'applications dans les réseaux mobiles cellulaires actuels, particulièrement Long Term Evolution (LTE) et LTE-Advanced (LTE-A) , ne peut être effectif sans surmonter les challenges posés par le déploiement d’un grand nombre d’équipement MTC dans la même cellule. En effet, le déploiement d'une myriade d'appareils MTC causera une congestion et une surcharge du système des réseaux d'accès radio (RAN) et du cœur de réseau (CN). Comme les appareils MTC sont équipés d'une batterie non rechargeable, la consommation d'énergie est aussi un défi. Dans cette thèse, nous allons étudier les problèmes de congestion et de consommation d'énergie dans le contexte des réseaux LTE et LTE-A en présence des appareils M2M. En ce qui concerne la congestion et la surcharge de système, nous nous concentrons sur la partie RAN, puisqu'elle peut être considérée comme la première ligne de défense pour le réseau cellulaire. Les contributions de cette thèse sont organisées sous les axes suivants: 1) Proposition d'un algorithme générique pour prédire le trafic entrant, de sorte que la congestion dans le réseau peut être facilement résolue, 2) Étude et proposition d'un modèle analytique générique de la procédure d'accès aléatoire au canal (RACH). Le modèle a pour but l’évaluation des méthodes de contrôle de congestion ciblant la partie RAN, 3) Approfondissement et proposition des méthodes permettant d'améliorer la méthode Pagination de Groupe (GP) approuvée par le 3GPP pour contrôler la congestion
The current and next generation wireless cellular networks (5G) have to deal with not only communications between people (known as Human-to-Human - H2H), but also with a massive deployment of Machine-Type-Communication (MTC). MTC, or alternatively Machine-to-Machine (M2M), can be viewed as devices connected among them without any human intervention. M2M can be considered as the cornerstone of Internet-of-Things (IoT) vision. It attracts a lot of attention, since it can be considered as a new opportunity and business market. Nowadays, there is a vast number of MTC applications, covering a large number of fields. Some of these applications are Healthcare, Intelligent Transport System (ITS), smart metering and smart grids, public safety (PS), forming the so-called smart city. Deploying this type of applications in the current cellular mobile networks, especially Long Term Evolution (LTE) and LTE-Advanced (LTE-A), cannot be achieved before overcoming the accompanied challenges. Indeed, caused by the existence of a myriad of MTC devices, Radio Access Network (RAN) and Core Network (CN) congestion and system overload is one of these challenging issues. As the MTC devices are using non-rechargeable batteries, power consumption is also a challenge. In this thesis, we study the congestion and power consumption problems in the context of LTE and LTE-A networks featuring M2M communications. Regarding the congestion and system overload, the focus will be on the RAN part since it can be considered as the first defense line on the network. The contributions of the thesis are organized on the following axes: 1) Propose a general algorithm to predict the incoming traffic, so that the congestion in the network can be easily remedied, 2) Study and propose a general analytical model of the Random Access Channel (RACH) procedure. The model can help to evaluate the congestion control methods targeting the RAN part, 3) Depth study and propose methods improving the performance of Group Paging (GP) method, one of the methods approved by 3GPP to control the congestion

This thesis investigates how resource and topology management techniques can be applied to achieve energy efficiency while maintaining acceptable quality of service (QoS) in heterogeneous cellular networks comprising high power macrocells and dense deployment of low power small cells. Partially centralised resource and topology management algorithms involving the sharing of decision making responsibilities regarding resource utilization and activation or deactivation of small cells among macrocells, small cells and a central node are developed. Resource management techniques are proposed to enable mobile users to be served by resources of a few small cells. A topology management scheme is applied to switch off idle small cells and switch on sleeping cells in accordance with traffic load and QoS. Resource management techniques, when combined with the topology management technique, achieve significant energy efficiency. A choice restriction technique that restricts users to resources from only a subset of suitable small cells is proposed to mitigate interference and improve QoS. A good balance between energy efficiency and QoS is achieved through this approach. Furthermore, energy saving under different generations of small cell base stations is investigated to provide insights to guide the design of energy saving strategies and the enhancement of existing ones. Also, an online, adaptive energy efficient joint resource and topology management technique is developed to correct deteriorating QoS conditions automatically by using a novel confidence level strategy to estimate QoS and regulate decision making epochs at the central node. Finally, a novel linear search scheme is applied together with database records of performance metrics to select appropriate resource and topology management policies for different traffic loads. This approach achieves better balance between QoS and energy efficiency than previous schemes proposed in the literature.

New technologies are expected to play a major role for wireless cellular systems beyond the existing 4G paradigm. The need for several orders of magnitude increase in system capacity has led to the proliferation of low-powered cellular layers overlaid on the existing macrocell layer. This type of network consisting of different cellular layers, each with their unique characteristics including transmission power and frequency of operation among others is termed as a heterogeneous network (HetNet). The emergence of HetNets leads to several research challenges and calls for a profound rethinking of several existing approaches for mobility management and interference management among other issues.

L’exigence de débit de données dans les communications sans fil due à l’emploi de smartphones, d’ordinateurs portables, de tablettes et de capteurs augmente considérablement. Cela pose directement des demandes extraordinaires sur de précieuses ressources spectrales. Pour satisfaire la saturation attendue sur les bandes actuellement utilisées, les systèmes de communication modernes permettent une réutilisation très fréquente des fréquences spatiales et évoluent vers des réseaux hétérogènes de stations de base (BS) couvrant des zones plus petites (petites cellules). De toute évidence, un tel système souffre des conditions d’interférence intercellulaires préjudiciables, en particulier aux bords des cellules. Par conséquent, il est clairement convaincant que la gestion des interférences est un goulot d’étranglement pour les réseaux sans fil actuels et futurs. Les schémas de traitement multicellulaire (MCP) ont été principalement utilisés pour fournir aux BS des versions quantifiées des signaux d’émission / réception d’autres BS via des liaisons de liaison (permettant le décodage en cluster. Il est alors possible que les données utilisateur soient traitées conjointement par plusieurs BS) à la fois en liaison montante et en liaison descendante, imitant ainsi les avantages du MIMO virtuel. Cependant, la mise en oeuvre de MCP pour toutes les BS du réseau est assez difficile en pratique en raison de la grande complexité de calcul et des retards excessifs, même pour les grands réseaux modérés. Cependant, diviser le réseau en plusieurs clusters et les laisser coopérer au sein de chaque cluster plutôt que sur l’ensemble du réseau apporte également certains avantages du MCP en ne nécessitant que les signaux reçus locaux et le CSI local. Nous appelons ce cadre MCP local, ce qui améliore également la robustesse du réseau aux échecs de connexion et l’évolutivité. Dans cette thèse, nous avons étudié les avantages de MCP local dans la gestion des interférences pour modèle de réseau hexagonal sectorisé sous trois scénarios différents. Dans le premier, nous avons supposé que le BS peut coopérer par le biais de liaisons à capacité limitée pour un nombre donné de cycles de coopération. Nous avons proposé un nouveau schéma de regroupement pratique qui adapte la façon dont les BS coopèrent à la sectorisation des cellules. Plus haut et plus bas et limites supérieures des degrés de liberté par utilisateur (DoF) en fonction de la coopération de nombres et la capacité de raccordement a été dérivée et une analyse SNR finie a ét é effectuée. Dans le deuxième scénario, nous supposé un système cellulaire multi-cloud, o`u chaque processeur central (CP) a une puissance de traitement limitée. UNE un schéma de clustering a été proposé qui adapte l’association entre BS et CP à la sectorisation. Limite inférieure du DoF par utilisateur en fonction de la capacité de liaison, de la capacité de CP et du rapport du nombre de Le CP en nombre de BS a ét é dérivé. Dans le dernier scénario, nous avons supposé à nouveau un cellulaire basé sur plusieurs nuages et appliqué des systèmes de calcul et de transfert (CoF) et de CoF quantifiés au clustering proposé. Pour CoF quantifié, nous avons proposé une méthode pour réduire le nombre de codes de réseau imbriqués pour réduire la mise en oeuvre complexité tout en conservant une dégradation raisonnable des performances
The data rate requirement in wireless communication due to employment of smartphones, laptops, tablets and sensors is increasing drastically. This directly poses extra-ordinary demands on precious spectral resources. To satisfy with the expected saturation on the currently used bands, modern communication systems are allowing very aggressive spatial frequency reuse and moving towards heterogenous networks of base stations (BS) covering smaller areas (small cells). Evidently, such system suffer from the detrimental inter-cell interference conditions, particularly at cell edges. Therefore, it is clearly convincing that interference management is a bottleneck for current and future wireless networks. Multi-cell processing (MCP) schemes has mostly been used to provide BSs with quantized versions of the transmit/receive signals of other BSs via backhaul/fronthaul links (allowing for clustered decoding). It is then possible for user data to be jointly processed by several BSs at both uplink and downlink, hence imitating the benefits of virtual MIMO. However, the implementation of MCP for all the BSs of the network is quite challenging in practice due to large computational complexity and excessive delays even for moderately large networks. However, dividing the network into several clusters and letting them to cooperate within each cluster rather than the entire network also brings some benefit of MCP by requiring only local received signals and local CSI. We name this framework as local MCP, which also improves the robustness of the network to connection failures and scalability. In this thesis, we have investigated the benefits of local MCP in interference management for sectored hexagonal network model under three different scenarios. In the first one, we assumed that the BS can cooperate through limited capacity links for a given number of cooperation rounds. We proposed a new practical clustering scheme that adapts the way BSs cooperate to cells sectorization. Upper and lower bounds on the peruser degrees-of-freedom (DoF) as a function of number cooperation round and backhaul capacity have been derived, and finite SNR analysis has been done. In the second scenario, we assumed a multi-cloud cellular system, where each central processor (CP) has a limited processing power. A clustering scheme has been proposed that adapts the association between BSs and CPs to the sectorization. Lower bound on the per-user DoF as a function of fronthaul capacity, CP capacity and the ratio of number of CP to number of BS has been derived. In the last scenario, we assumed again a multi-cloud based cellular system, and applied compute-and-forward (CoF) and Quantized CoF schemes to the proposed clustering. For Quantized CoF, we proposed a method for reducing the number of nested lattice codes to lower the implementation complexity while keeping reasonable performance degradation

Doctor of Philosophy (Ph.D.)
The buzzword of this decade has been convergence: the convergence of telecommunications, Internet, entertainment, and information technologies for the seamless provisioning of multimedia services across different network types. Thus the future Next Generation Mobile Network (NGMN) can be envisioned as a group of co-existing heterogeneous mobile data networking technologies sharing a common Internet Protocol (IP) based backbone. In such all-IP based heterogeneous networking environments, ongoing sessions from roaming users are subjected to frequent vertical handoffs across network boundaries. Therefore, ensuring uninterrupted service continuity during session handoffs requires successful mobility and session management mechanisms to be implemented in these participating access networks. Therefore, it is essential for a common interworking framework to be in place for ensuring seamless service continuity over dissimilar networks to enable a potential user to freely roam from one network to another. For the best of our knowledge, the need for a suitable unified mobility and session management framework for the NGMN has not been successfully addressed as yet. This can be seen as the primary motivation of this research. Therefore, the key objectives of this thesis can be stated as:  To propose a mobility-aware novel architecture for interworking between heterogeneous mobile data networks  To propose a framework for facilitating unified real-time session management (inclusive of session establishment and seamless session handoff) across these different networks. In order to achieve the above goals, an interworking architecture is designed by incorporating the IP Multimedia Subsystem (IMS) as the coupling mediator between dissipate mobile data networking technologies. Subsequently, two different mobility management frameworks are proposed and implemented over the initial interworking architectural design. The first mobility management framework is fully handled by the IMS at the Application Layer. This framework is primarily dependant on the IMS’s default session management protocol, which is the Session Initiation Protocol (SIP). The second framework is a combined method based on SIP and the Mobile IP (MIP) protocols, which is essentially operated at the Network Layer. An analytical model is derived for evaluating the proposed scheme for analyzing the network Quality of Service (QoS) metrics and measures involved in session mobility management for the proposed mobility management frameworks. More precisely, these analyzed QoS metrics include vertical handoff delay, transient packet loss, jitter, and signaling overhead/cost. The results of the QoS analysis indicates that a MIP-SIP based mobility management framework performs better than its predecessor, the Pure-SIP based mobility management method. Also, the analysis results indicate that the QoS performances for the investigated parameters are within acceptable levels for real-time VoIP conversations. An OPNET based simulation platform is also used for modeling the proposed mobility management frameworks. All simulated scenarios prove to be capable of performing successful VoIP session handoffs between dissimilar networks whilst maintaining acceptable QoS levels. Lastly, based on the findings, the contributions made by this thesis can be summarized as:  The development of a novel framework for interworked heterogeneous mobile data networks in a NGMN environment.  The final design conveniently enables 3G cellular technologies (such as the Universal Mobile Telecommunications Systems (UMTS) or Code Division Multiple Access 2000 (CDMA2000) type systems), Wireless Local Area Networking (WLAN) technologies, and Wireless Metropolitan Area Networking (WMAN) technologies (e.g., Broadband Wireless Access (BWA) systems such as WiMAX) to interwork under a common signaling platform.  The introduction of a novel unified/centralized mobility and session management platform by exploiting the IMS as a universal coupling mediator for real-time session negotiation and management.  This enables a roaming user to seamlessly handoff sessions between different heterogeneous networks.  As secondary outcomes of this thesis, an analytical framework and an OPNET simulation framework are developed for analyzing vertical handoff performance. This OPNET simulation platform is suitable for commercial use.

La interfaz radio de los sistemas de comunicaciones móviles es normalmente considerada como la única limitación de capacidad en la red de acceso radio. Sin embargo, a medida que se van desplegando nuevas y más eficientes interfaces radio, y de que el tráfico de datos y multimedia va en aumento, existe la creciente preocupación de que la infraestructura de transporte (backhaul) de la red celular pueda convertirse en el cuello de botella en algunos escenarios. En este contexto, la tesis se centra en el desarrollo de técnicas de gestión de recursos que consideran de manera conjunta la gestión de recursos en la interfaz radio y el backhaul. Esto conduce a un nuevo paradigma donde los recursos del backhaul se consideran no sólo en la etapa de dimensionamiento, sino que además son incluidos en la problemática de gestión de recursos. Sobre esta base, el primer objetivo de la tesis consiste en evaluar los requerimientos de capacidad en las redes de acceso radio que usan IP como tecnología de transporte, de acuerdo a las recientes tendencias de la arquitectura de red. En particular, se analiza el impacto que tiene una solución de transporte basada en IP sobre la capacidad de transporte necesaria para satisfacer los requisitos de calidad de servicio en la red de acceso. La evaluación se realiza en el contexto de la red de acceso radio de UMTS, donde se proporciona una caracterización detallada de la interfaz Iub. El análisis de requerimientos de capacidad se lleva a cabo para dos diferentes escenarios: canales dedicados y canales de alta velocidad. Posteriormente, con el objetivo de aprovechar totalmente los recursos disponibles en el acceso radio y el backhaul, esta tesis propone un marco de gestión conjunta de recursos donde la idea principal consiste en incorporar las métricas de la red de transporte dentro del problema de gestión de recursos. A fin de evaluar los beneficios del marco de gestión de recursos propuesto, esta tesis se centra en la evaluación del problema de asignación de base, como estrategia para distribuir el tráfico entre las estaciones base en función de los niveles de carga tanto en la interfaz radio como en el backhaul. Este problema se analiza inicialmente considerando una red de acceso radio genérica, mediante la definición de un modelo analítico basado en cadenas de Markov. Dicho modelo permite calcular la ganancia de capacidad que puede alcanzar la estrategia de asignación de base propuesta. Posteriormente, el análisis de la estrategia propuesta se extiende considerando tecnologías específicas de acceso radio. En particular, en el contexto de redes WCDMA se desarrolla un algoritmo de asignación de base basado en simulatedannealing cuyo objetivo es maximizar una función de utilidad que refleja el grado de satisfacción de las asignaciones respecto los recursos radio y transporte. Finalmente, esta tesis aborda el diseño y evaluación de un algoritmo de asignación de base para los futuros sistemas de banda ancha basados en OFDMA. En este caso, el problema de asignación de base se modela como un problema de optimización mediante el uso de un marco de funciones de utilidad y funciones de coste de recursos. El problema planteado, que considera que existen restricciones de recursos tanto en la interfaz radio como en el backhaul, es mapeado a un problema de optimización conocido como Multiple-Choice Multidimensional Knapsack Problem (MMKP). Posteriormente, se desarrolla un algoritmo de asignación de base heurístico, el cual es evaluado y comparado con esquemas de asignación basados exclusivamente en criterios radio. El algoritmo concebido se basa en el uso de los multiplicadores de Lagrange y está diseñado para aprovechar de manera simultánea el balanceo de carga en la intefaz radio y el backhaul.

Economic affordability of services and infrastructures has rapidly become one of the key issues in the evaluation and design of wireless access systems. The provisioning of high data rates, at an ``affordable'' price, constitutes a serious challenge to the structure and management of current and future wireless networks.

The management of radio resources, Radio Resource Management or RRM for short, has traditionally been benchmarked mostly by technical merits such as throughput (data delivery capability) and Quality of Service (QoS). When comparing different RRM schemes, the scheme that can deliver more bits per Hertz (unit of bandwidth) or per Euro is often assumed the more efficient. From an economic point of view, however, cost efficiency is not equivalent to profitability.

We conjecture that the economic efficiency and profitability can be improved both by better technical efficiency and by better accounting for users' service appreciation and willingness to pay. While we shall, primarily treat the operator's benefit of improved RRM, we will try to improve the RRM by means of being more responsive to the demands of the users. In eight conference and journal papers, we investigate: Provisioning of support for asymmetric traffic, Quality and pricing aware resource management and Creation of forwarding incentive in multihop cellular networks.

We show that implementing support for asymmetric links can improve the efficiency of (service) production in Time Division Duplexing (TDD) mode wireless networks with asymmetric traffic. That is, more traffic can be handled with the same system resources. Compared to Frequency Division Duplexing (FDD), TDD offers more flexible use of spectrum resources. The benefits of TDD and support for asymmetric links are readily available for systems providing high-rate spotty coverage. For systems aiming at full coverage and tight reuse, however, proper measures must be taken to control inter-mobile- and inter-base-station-interference.

We present the MEDUSA model framework for taking users' service appreciation and willingness to pay into account in performance evaluations of wireless networks with elastic traffic. Assuming that user satisfaction depends on both the quality and the price of the service, numerical experiments show that the economic efficiency of an RRM scheme is affected by the pricing scheme. We also introduce the concepts of speculative resource management to exploit traffic elasticity and improve resource utilisation. With speculative admission control, users with good propagation conditions may be admitted to a full system at the expense of a slight degradation of the QoS of some or all users, if the expected total revenue would thereby increase. Results indicate significant revenue gain with speculative admission control. Service perception aware scheduling was evaluated as a means to improve resource utilisation, but yielded only marginal gain compared to a weighted proportional fair scheduler.

For the third area studied in this Thesis, i.e. multihopping in cellular networks, economic efficiency was both the goal and one of the means to achieve it. By means of a resource re-distribution scheme called Resource Delegation we eliminated the bandwidth bottle neck of the relays. We combined Resource Delegation with economic compensation for the energy expenditures of the relays and were able to achieve significantly increased operator revenue with maintained or improved user utility. Assuming that the added complexity of keeping track of reward transactions is negligible, profitability was correspondingly improved.

The explosive growth of data traffic demands, emanating from smart mobile devices and bandwidth-consuming applications on the cellular network poses the need to drastically modify the cellular network architecture. A challenge faced by the network operators is the inability of the finite spectral resources to support the growing data traffic. The Next Generation Network (NGN) is expected to meet defined requirements such as massively connecting billions of devices with heterogeneous applications and services through enhanced mobile broadband networks, which provides higher data rates with improved network reliability and availability, lower end-to-end latency and increased energy efficiency. Device-to-Device (D2D) communication is one of the several emerging technologies that has been proposed to support NGN in meeting these aforementioned requirements. D2D communication leverages the proximity of users to provide direct communication with or without traversing the base station. Hence, the integration of D2D communication into cellular networks provides potential gains in terms of throughput, energy efficiency, network capacity and spectrum efficiency. D2D communication underlaying a cellular network provides efficient utilisation of the scarce spectral resources, however, there is an introduction of interference emanating from the reuse of cellular channels by D2D pairs. Hence, this dissertation focuses on the technical challenge with regards to interference management in underlay D2D communication. In order to tackle this challenge to be able to exploit the potentials of D2D communication, there is the need to answer some important research questions concerning the problem. Thus, the study aims to find out how cellular channels can be efficiently allocated to D2D pairs for reuse as an underlay to cellular network, and how mode selection and power control approaches influence the degree of interference caused by D2D pairs to cellular users. Also, the research study continues to determine how the quality of D2D communication can be maintained with factors such as bad channel quality or increased distance. In addressing these research questions, resource management techniques of mode selection, power control, relay selection and channel allocation are applied to minimise the interference caused by D2D pairs when reusing cellular channels to guarantee the Quality of Service (QoS) of cellular users, while optimally improving the number of permitted D2D pairs to reuse channels. The concept of Open loop power control scheme is examined in D2D communication underlaying cellular network. The performance of the fractional open loop power control components on SINR is studied. The simulation results portrayed that the conventional open loop power control method provides increased compensation for the path loss with higher D2D transmit power when compared with the fractional open loop power control method. Furthermore, the problem of channel allocation to minimise interference is modelled in two system model scenarios, consisting of cellular users coexisting with D2D pairs with or without relay assistance. The channel allocation problem is solved as an assignment problem by using a proposed heuristic channel allocation, random channel allocation, Kuhn-Munkres (KM) and Gale-Shapley (GS) algorithms. A comparative performance evaluation for the algorithms are carried out in the two system model scenarios, and the results indicated that D2D communication with relay assistance outperformed the conventional D2D communication without relay assistance. This concludes that the introduction of relay-assisted D2D communication can improve the quality of a network while utilising the available spectral resources without additional infrastructure deployment costs. The research work can be extended to apply an effective relay selection approach for a user mobility scenario.

Face à la croissance exponentielle des réseaux mobiles très haut débit, les opérateurs de téléphonie mobile se sont lancé dans le déploiement des réseaux dits hiérarchiques (HetNet), composés par des sous-réseaux avec des caractéristiques divergentes en termes de type des cellules déployées et des technologies d’accès radio utilisées. Avec ce caractère hétérogène des réseaux cellulaire, l’exploitation de ces derniers devienne de plus en plus compliquée et coûteuse impliquant le déploiement, la configuration et la reconfiguration de stations de base et d’équipements de différentes caractéristiques. Ainsi, l’intégration dans les réseaux HetNet de fonctionnalités d’auto-configuration automatisant et simplifiant l’exploitation des réseaux deviennent une demande forte des opérateurs. Cette thèse a pour objectif l’étude et le développement de solutions de gestion dynamique de l’équilibrage de charges entre les différentes couches composant un même HetNet, pour une expérience utilisateur (QoE) améliorée. Dans ce contexte, une classe des algorithmes d’équilibrage de charges dite ‘équilibrage de charges par adaptation dynamique des paramètres de la procédure de handover’ est étudiée. Pour commencer, nous développons un modèle théorique basé sur des solutions et des outils de la géométrie stochastique et incorporant le caractère hétérogène des réseaux cellulaires. Ensuite nous exploitons ce modèle pour introduire des algorithmes d’adaptation des paramètres de handover basés sur la maximisation de la puissance reçue et du rapport signal/brouillage plus bruit (SINR). Nous exploitons ces résultats pour implémenter et étudier, par simulation à évènements discrets, des algorithmes d’équilibrage de charges dans le contexte des réseaux LTE HetNet auto-organisés basés sur les spécifications 3GPP. Ces travaux soulignent l’importance de l’équilibrage de charges afin de booster les performances des réseaux cellulaires en termes de débit global transmis, perte de paquets de données et utilisation optimisée des ressources radio
High demands on mobile networks provide a fresh opportunity to migrate towardsmulti-tier deployments, denoted as heterogeneous network (HetNet), involving a mix of cell types and radio access technologies working together seamlessly. In this context, network optimisation functionalities such as load balancing have to be properly engineered so that HetNet benefit are fully exploited. This dissertation aims to develop tractable frameworks to model and analyze load balancing dynamics while incorporating the heterogeneous nature of cellular networks. In this context we investigate and analyze a class of load balancingstrategies, namely adaptive handover based load balancing strategies. These latter were firstly studied under the general heading of stochastic networks using independent and homogeneous Poisson point processes based network model. We propose a baseline model to characterize rate coverage and handover signalling in K-tier HetNet with a general maximum power based cell association and adaptive handover strategies. Tiers differ in terms of deployment density and cells characteristics (i.e. transmit power, bandwidth, and path loss exponent). One of the main outcomes is demonstrating the impact of offloading traffic from macro- to small-tier. This impact was studied in terms of rate coverage and HO signalling. Results show that enhancement in rate coverage is penalized by HO signalling overhead. Then appropriate algorithms of LB based adaptive HO are designed and their performance is evaluated by means of extensive system level simulations. These latter are conducted in 3GPP defined scenarios, including representation of mobility procedures in both connectedstate. Simulation results show that the proposed LB algorithms ensure performance enhancement in terms of network throughput, packet loss ratio, fairness and HO signalling

Historically mobile Radio Access Networks (RANs) were optimised initially to maximise coverage and subsequently to improve capacity, user data rates and quality of service. However, the recent exponential growth in the volume of transmitted data coupled with the ever increasing energy costs has highlighted the need to optimise futuristic RANs from an energy efficiency perspective. This research study postulated the utilisation of radio resource management approaches to improve the energy efficiency of modern RANs, with a particular emphasis on the radio frequency energy performance. The research study yielded the following major outcomes. First, there was notable positive correlation between user channel quality improvements and the energy efficiency of RANs. Second, channel quality aware packet schedulers were more energy efficient than channel quality ignorant packet schedulers. Third, energy aware scheduling metrics coupled with power control algorithms can be utilised to optimise and refine the energy efficiency performance of the rate adaptive frequency domain packet scheduling. Fourth, the dynamic temporal and spatial traffic load characteristics, in the radio access network, present energy saving opportunities through collaborative and cooperative Inter-Cell Interference (ICI) management among neighbouring base stations. While the results presented in this thesis pertain to radio frequency and/or radio head energy consumption, the improved energy efficiency could be leveraged by increasing the inter site distance between base stations subsequently reducing the density of base stations in any given geographical area thus reducing the energy consumption of the RANs as a whole. The benefits of energy efficient RANs are twofold, i.e. reduction in the amount of CO2 emission and lower operating expenditure (OPEX).

Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, System Design and Management Program, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 96-103).
Cellular agriculture is an emerging field to develop in-vitro agricultural products. Despite overwhelming public attention towards the field's trajectory, there are significant research hurdles to overcome in order to validate scalable applications. These challenges, referring to the translational development of cell lines, serum-free media, cell-scaffolds, and bioreactor designs with regulatory and market assessment efforts, require new models for industry collaboration. The Open-Innovation Network Map was used to prioritize key collaboration networks to address the translational challenges of cellular agriculture, and three in-depth case studies from open-source models, big-science collaborations, and pre-competitive consortia were evaluated. Nine best practices to support open innovation across translational development were surfaced: Open-Source Models I OpenCompute Foundation, a community for open-source data center hardware designs, highlights the focus on: (1) the modularization of biological parts, equipment and protocols to encourage reproducibility, (2) the scalability of proof-of-concepts through industry participation, and (3) the self-assembly of industry clusters to initiate standardization. Big-Science Collaborations I The Human Genome Project, a large-scale collaboration to complete the sequencing of the human genome, exhibits attributes of successful research-intensive organizations, such as: (4) the centralization of leadership in distributed networks, and (5) policies to increase data-sharing frequency. Pre-competitive Consortia I SEMATECH, a semi-conductor manufacturing consortium established to address bottlenecks in the product development process, reveals that: (6) a crisis is critical for industry cohesion, (7) investment in innovation hubs increases translatability across stakeholders, (8) 'honest brokers' should be created to promote trust, and (9) feedback loops with end-users are critical to test market applications for new scientific advancements. The building of cellular agriculture's communities, channels, and technologies with appropriate open innovation models can enable stakeholders to collaborate and maintain a competitive edge. The conclusions of the thesis represent a convergence point among industry, academia and policy to discuss how to best shape and execute open innovation efforts in the future.
by Kevin Ka-Chun Yuen.
S.M. in Engineering and Management

Location Management is defined as the process of tracking the position of a mobile terminal when it moves to its associated area within the network. This allows the network to detect the mobile user’s path for the purpose of call delivery. The location management schema in a public-LAN mobile network (IS-41 and GSM) is based on centralized two-tier database architecture. The root level is called the Home Location Register (HLR) and the second level is called the Visitor Location Register (VLR). The HLR permanently stores all the mobile users’ location information and the types of services subscribed in the user’s profile database. The VLR stores the location information whenever a user registered in the HLR moves to its related location area within the network. By contacting the HLR, the VLR authenticates and updates the mobile user’s current position when a mobile terminal moves from one location area to another. The HLR then updates the mobile terminal’s new location information and removes the mobile terminal from its previous VLR. There can be multiple VLR’s under each HLR in a network. In the current location management schema, all the information requests, queries, acknowledgements have to go through the HLR. This results in excessive overload at the HLR. This overload becomes high when the number of mobile terminals increases within the network. The heavy traffic at the root (HLR) may cause congestion, degradation of the bandwidth at the root and hence becomes a major bottleneck for the entire network. To solve this congestion/bottleneck problem, a modified iterative protocol with VLR cache was introduced, where the VLRs in the network handle all de-registration, registration and acknowledgement of messages. The HLR only handles updating the location information of the mobile terminal in its database. This reduced the excess load/traffic experienced at the HLR thus improving the network’s performance. The modified protocol was tested with different cache replacement policies such as First-In First-Out (FIFO), Random and Least Frequently Visited (LFV) with uniform traffic with random mobile terminal movement. In this thesis report, we extend the previous work in the modified iterative protocol by 1) increasing the topography of the network, to analyze the impact of network’s size on performance and 2) changing the mobile terminal traffic pattern from uniform traffic with random mobile terminal movement to non-uniform traffic with unbalanced probability movement. With these changes, we analyzed the modified protocol’s performance with different cache replacement policies (FIFO, LFV and Random) under uniform traffic with random movement and non-uniform traffic with unbalanced probability movement.

La bonne gestion des ressources radio est un élément clé pour offrir une bonne Qualité de Service (QdS) pour les utilisateurs tout en assurant la meilleure gestion des ressources du réseau. Nous évaluons la performance de certaines fonctionnalités de gestion de ressources, à savoir l’ordonnancement et l'accès MAC et dans une deuxième étape nous proposons des méthodes de coordination de la puissance dans les liens ascendants et descendants des systèmes LTE. Nous proposons des mécanismes de coordination des interférences dans les systèmes LTE dans le cadre de l’auto-optimisation des réseaux (Self-Optimizing Networks). Le problème est modélisé par un système multi-agent effectuant un apprentissage par renforcement. La théorie de l’apprentissage de système d’inférence floue permet d’apprendre, à partir de l’expérience les décisions optimales correspondant à chaque état du système. La logique floue permet de gérer l’état continu du système. Chaque station de base est alors un agent responsable de modéliser son propre état et l’état des stations voisines et de calculer des récompenses tout au long du processus d’apprentissage afin d’apprendre la politique optimale de façon distribuée mais coopérative. Dans le sens descendant, le but est de décider la quantité de puissance allouée par spectre, dans un contexte de réutilisation totale du spectre. Dans le sens montant, nous proposons une optimisation dynamique du mécanisme de compensation partielle de puissance, Fractional Power Control, standardisé par le 3GPP. L’algorithme de gestion de puissance est adapté pour l’optimisation des performances dans ce contexte sujet à des variations très rapides et chaotiques.

As today's global competition grows in manufacturing industries companies are forced to work smart in all areas of operations, starting with suppliers and ending with customers. This competition in general requires firms to improve market responsiveness, product quality, use computerised information systems for production planning and control, have more rapid changeovers, reductions in setup times, work-in-progress reduction and hence throughput time reduction. In order to accomplish these formidable tasks, there are a number of management philosophies available for manufacturing companies. These include just-in-time, flexible manufacturing systems, computer integrated manufacturing, total quality management, concurrent engineering. Implementation of these philosophies, however, requires mass mobilisation encompassing many areas of operations such as production, sales and marketing, suppliers, finance, customer servicing, product design and method engineering, maintenance, personnel and training, etc. This thesis details a study which evaluates the total quality management philosophy in cellular manufacturing environment. Following this evaluation, a quality management information scheme, which is structured and integrated, has been produced using the Manufacturing Systems Analysis and Design Method. In order to manage smoothly this mobilisation and incorporate the scheme to other integrated functional areas, a new approach namely the Activity Based Implementation (ABI) has also been produced. Justification of the model from various points of view has shown that the model is expected to address a considerable gap in the area concerned. The model was designed to be used as an integrated part of a system or as a stand-alone scheme by quality practitioners, the management board of organisations implementing TQM and quality management researchers.