67 research outputs found
Traffic pattern prediction in cellular networks.
PhDIncreasing numbers of users together with a more use of high bit-rate services complicate radio resource management in 3G systems. In order to improve the system capacity and guarantee the QoS, a large amount of research had been carried out on radio resource management. One viable approach reported is to use semi-smart antennas to dynamically change the radiation pattern of target cells to reduce congestion.
One key factor of the semi-smart antenna techniques is the algorithm to adjust the beam pattern to cooperatively control the size and shape of each radio cell. Methods described in the literature determine the optimum radiation patterns according to the current observed congestion. By using machine learning methods, it is possible to detect the upcoming change of the traffic patterns at an early stage and then carry out beamforming optimization to alleviate the reduction in network performance.
Inspired from the research carried out in the vehicle mobility prediction field, this work learns the movement patterns of mobile users with three different learning models by analysing the movement patterns captured locally. Three different mobility models are introduced to mimic the real-life movement of mobile users and provide analysable data for learning.
The simulation results shows that the error rates of predictions on the geographic distribution of mobile users are low and it is feasible to use the proposed learning models to predict future traffic patterns. Being able to predict these patterns mean that the optimized beam patterns could be calculated according to the predicted traffic patterns and loaded to the relevant base stations in advance
Cooperative control of relay based cellular networks
PhDThe increasing popularity of wireless communications and the higher data
requirements of new types of service lead to higher demands on wireless networks.
Relay based cellular networks have been seen as an effective way to meet users’
increased data rate requirements while still retaining the benefits of a cellular
structure. However, maximizing the probability of providing service and spectrum
efficiency are still major challenges for network operators and engineers because of
the heterogeneous traffic demands, hard-to-predict user movements and complex
traffic models.
In a mobile network, load balancing is recognised as an efficient way to increase
the utilization of limited frequency spectrum at reasonable costs. Cooperative
control based on geographic load balancing is employed to provide flexibility for
relay based cellular networks and to respond to changes in the environment.
According to the potential capability of existing antenna systems, adaptive radio
frequency domain control in the physical layer is explored to provide coverage at
the right place at the right time.
This thesis proposes several effective and efficient approaches to improve
spectrum efficiency using network wide optimization to coordinate the coverage
offered by different network components according to the antenna models and
relay station capability. The approaches include tilting of antenna sectors,
changing the power of omni-directional antennas, and changing the assignment of
relay stations to different base stations. Experiments show that the proposed
approaches offer significant improvements and robustness in heterogeneous traffic
scenarios and when the propagation environment changes. The issue of predicting
the consequence of cooperative decisions regarding antenna configurations when
applied in a realistic environment is described, and a coverage prediction model is
proposed. The consequences of applying changes to the antenna configuration on
handovers are analysed in detail. The performance evaluations are based on a
system level simulator in the context of Mobile WiMAX technology, but the
concepts apply more generally
An intelligent-agent approach for managing congestion in W-CDMA networks
PhDResource Management is a crucial aspect in the next generation cellular networks
since the use of W-CDMA technology gives an inherent flexibility in managing the
system capacity. The concept of a “Service Level Agreement” (SLA) also plays a
very important role as it is the means to guarantee the quality of service provided to
the customers in response to the level of service to which they have subscribed.
Hence there is a need to introduce effective SLA-based policies as part of the radio
resource management.
This work proposes the application of intelligent agents in SLA-based control in
resource management, especially when congestion occurs. The work demonstrates the
ability of intelligent agents in improving and maintaining the quality of service to
meet the required SLA as the congestion occurs.
A particularly novel aspect of this work is the use of learning (here Case Based
Reasoning) to predict the control strategies to be imposed. As the system environment
changes, the most suitable policy will be implemented. When congestion occurs, the
system either proposes the solution by recalling from experience (if the event is
similar to what has been previously solved) or recalculates the solution from its
knowledge (if the event is new). With this approach, the system performance will be
monitored at all times and a suitable policy can be immediately applied as the system
environment changes, resulting in maintaining the system quality of service
Load balancing using cell range expansion in LTE advanced heterogeneous networks
The use of heterogeneous networks is on the increase, fueled by consumer demand for more data. The main objective of heterogeneous networks is to increase capacity. They offer solutions for efficient use of spectrum, load balancing and improvement of cell edge coverage amongst others. However, these solutions have inherent challenges such as inter-cell interference and poor mobility management. In heterogeneous networks there is transmit power disparity between macro cell and pico cell tiers, which causes load imbalance between the tiers. Due to the conventional user-cell association strategy, whereby users associate to a base station with the strongest received signal strength, few users associate to small cells compared to macro cells. To counter the effects of transmit power disparity, cell range expansion is used instead of the conventional strategy. The focus of our work is on load balancing using cell range expansion (CRE) and network utility optimization techniques to ensure fair sharing of load in a macro and pico cell LTE Advanced heterogeneous network. The aim is to investigate how to use an adaptive cell range expansion bias to optimize Pico cell coverage for load balancing. Reviewed literature points out several approaches to solve the load balancing problem in heterogeneous networks, which include, cell range expansion and utility function optimization. Then, we use cell range expansion, and logarithmic utility functions to design a load balancing algorithm. In the algorithm, user and base station associations are optimized by adapting CRE bias to pico base station load status. A price update mechanism based on a suboptimal solution of a network utility optimization problem is used to adapt the CRE bias. The price is derived from the load status of each pico base station. The performance of the algorithm was evaluated by means of an LTE MATLAB toolbox. Simulations were conducted according to 3GPP and ITU guidelines for modelling heterogeneous networks and propagation environment respectively. Compared to a static CRE configuration, the algorithm achieved more fairness in load distribution. Further, it achieved a better trade-off between cell edge and cell centre user throughputs. [Please note: this thesis file has been deferred until December 2016
Load Balancing of Elastic Data Traffic in Heterogeneous Wireless Networks
The increasing amount of mobile data traffic has resulted in an architectural innovation in cellular networks through the introduction of heterogeneous networks. In heterogeneous networks, the deployment of macrocells is accompanied by the use of low power pico and femtocells (referred to as microcells) in hot spot areas inside the macrocell which increase the data rate per unit area.
The purpose of this thesis is to study the load balancing problem of elastic data traffic in heterogeneous wireless networks. These networks consist of different types of cells with different characteristics. Individual cells are modelled as an M/G/1 - PS queueing system. This results in a multi-server queueing model consisting of a single macrocell with multiple microcells within the area. Both static and dynamic load balancing schemes are developed to balance the data flows between the macrocell and microcells so that the mean flow-level delay is minimized. Both analytical and numerical methods are used for static policies. For dynamic policies, the performance is evaluated by simulations.
The results of the study indicate that all dynamic policies can significantly improve the flow-level delay performance in the system under consideration compared to the optimal static policy. The results also indicate that MJSQ and MP are best policies although MJSQ needs less state information. The performance gain of most of the dynamic polices is insensitive with respect to the flow size distribution. In addition, many interesting tests are conducted such as the effect of increasing the number of microcells and the impact of service rate difference between macrocell and microcells
Identifying and diagnosing video streaming performance issues
On-line video streaming is an ever evolving ecosystem of services and technologies, where content providers are on a constant race to satisfy the users' demand for richer content and higher bitrate streams, updated set of features and cross-platform compatibility. At the same time, network operators are required to ensure that the requested video streams are delivered through the network with a satisfactory quality in accordance with the existing Service Level Agreements (SLA).
However, tracking and maintaining satisfactory video Quality of Experience (QoE) has become a greater challenge for operators than ever before. With the growing popularity of content engagement on handheld devices and over wireless connections, new points-of-failure have added to the list of failures that can affect the video quality. Moreover, the adoption of end-to-end encryption by major streaming services has rendered previously used QoE diagnosis methods obsolete.
In this thesis, we identify the current challenges in identifying and diagnosing video streaming issues and we propose novel approaches in order to address them. More specifically, the thesis initially presents methods and tools to identify a wide array of QoE problems and the severity with which they affect the users' experience. The next part of the thesis deals with the investigation of methods to locate under-performing parts of the network that lead to drop of the delivered quality of a service.
In this context, we propose a data-driven methodology for detecting the under performing areas of cellular network with sub-optimal Quality of Service (QoS) and video QoE. Moreover, we develop and evaluate a multi-vantage point framework that is capable of diagnosing the underlying faults that cause the disruption of the user's experience. The last part of this work, further explores the detection of network performance anomalies and introduces a novel method for detecting such issues using contextual information. This approach provides higher accuracy when detecting network faults in the presence of high variation and can benefit providers to perform early detection of anomalies before they result in QoE issues.La distribuciĂłn de vĂdeo online es un ecosistema de servicios y tecnologĂas, donde los proveedores de contenidos se encuentran en una carrera continua para satisfacer las demandas crecientes de los usuarios de más riqueza de contenido, velocidad de transmisiĂłn, funcionalidad y compatibilidad entre diferentes plataformas. Asimismo, los operadores de red deben asegurar que los contenidos demandados son entregados a travĂ©s de la red con una calidad satisfactoria segĂşn los acuerdos existentes de nivel de servicio (en inglĂ©s Service Level Agreement o SLA). Sin embargo, la monitorizaciĂłn y el mantenimiento de un nivel satisfactorio de la calidad de experiencia (en inglĂ©s Quality of Experience o QoE) del vĂdeo online se ha convertido en un reto mayor que nunca para los operadores. Dada la creciente popularidad del consumo de contenido con dispositivos mĂłviles y a travĂ©s de redes inalámbricas, han aparecido nuevos puntos de fallo que se han añadido a la lista de problemas que pueden afectar a la calidad del vĂdeo transmitido. Adicionalmente, la adopciĂłn de sistemas de encriptaciĂłn extremo a extremo, por parte de los servicios más importantes de distribuciĂłn de vĂdeo online, ha dejado obsoletos los mĂ©todos existentes de diagnĂłstico de la QoE. En esta tesis se identifican los retos actuales en la identificaciĂłn y diagnĂłstico de los problemas de transmisiĂłn de vĂdeo online, y se proponen nuevas soluciones para abordar estos problemas. Más concretamente, inicialmente la tesis presenta mĂ©todos y herramientas para identificar un conjunto amplio de problemas de QoE y la severidad con los que estos afectan a la experiencia de los usuarios. La siguiente parte de la tesis investiga mĂ©todos para localizar partes de la red con un rendimiento bajo que resultan en una disminuciĂłn de la calidad del servicio ofrecido. En este contexto, se propone una metodologĂa basada en el análisis de datos para detectar áreas de la red mĂłvil que ofrecen un nivel subĂłptimo de calidad de servicio (en inglĂ©s Quality of Service o QoS) y QoE. Además, se desarrolla y se evalĂşa una soluciĂłn basada en mĂşltiples puntos de medida que es capaz de diagnosticar los problemas subyacentes que causan la alteraciĂłn de la experiencia de usuario. La Ăşltima parte de este trabajo explora adicionalmente la detecciĂłn de anomalĂas de rendimiento de la red y presenta un nuevo mĂ©todo para detectar estas situaciones utilizando informaciĂłn contextual. Este enfoque proporciona una mayor precisiĂłn en la detecciĂłn de fallos de la red en presencia de alta variabilidad y puede ayudar a los proveedores a la detecciĂłn precoz de anomalĂas antes de que se conviertan en problemas de QoE.La distribuciĂł de vĂdeo online Ă©s un ecosistema de serveis i tecnologies, on els proveĂŻdors
de continguts es troben en una cursa continua per satisfer les demandes creixents del
usuaris de més riquesa de contingut, velocitat de transmissió, funcionalitat i compatibilitat
entre diferents plataformes. A la vegada, els operadors de xarxa han d’assegurar que
els continguts demandats són entregats a través de la xarxa amb una qualitat satisfactòria
segons els acords existents de nivell de servei (en anglès Service Level Agreement o SLA).
Tanmateix, el monitoratge i el manteniment d’un nivell satisfactori de la qualitat d’experiència (en anglès Quality of Experience o QoE) del vĂdeo online ha esdevingut un repte mĂ©s gran que mai per als operadors. Donada la creixent popularitat del consum de contingut amb dispositius mòbils i a travĂ©s de xarxes sense fils, han aparegut nous punts de fallada que s’han afegit a la llista de problemes que poden afectar a la qualitat del vĂdeo transmès. Addicionalment, l’adopciĂł de sistemes d’encriptaciĂł extrem a extrem, per part dels serveis mĂ©s importants de distribuciĂł de vĂdeo online, ha deixat obsolets els mètodes existents de diagnòstic de la QoE.
En aquesta tesi s’identifiquen els reptes actuals en la identificaciĂł i diagnòstic dels problemes de transmissiĂł de vĂdeo online, i es proposen noves solucions per abordar aquests problemes. MĂ©s concretament, inicialment la tesi presenta mètodes i eines per identificar un conjunt ampli de problemes de QoE i la severitat amb la que aquests afecten a la experiència dels usuaris. La segĂĽent part de la tesi investiga mètodes per localitzar parts de la xarxa amb un rendiment baix que resulten en una disminuciĂł de la qualitat del servei ofert.
En aquest context es proposa una metodologia basada en l’anà lisi de dades per detectar
à rees de la xarxa mòbil que ofereixen un nivell subòptim de qualitat de servei (en anglès Quality of Service o QoS) i QoE. A més, es desenvolupa i s’avalua una solució basada
en múltiples punts de mesura que és capaç de diagnosticar els problemes subjacents que
causen l’alteració de l’experiència d’usuari. L’última part d’aquest treball explora addicionalment la detecció d’anomalies de rendiment de la xarxa i presenta un nou mètode per detectar aquestes situacions utilitzant informació contextual. Aquest enfoc proporciona una major precisió en la detecció de fallades de la xarxa en presencia d’alta variabilitat i pot ajudar als proveïdors a la detecció precoç d’anomalies abans de que es converteixin en problemes de QoE.Postprint (published version
Improved planning and resource management in next generation green mobile communication networks
In upcoming years, mobile communication networks will experience a disruptive reinventing process through the deployment of post 5th Generation (5G) mobile networks. Profound impacts are expected on network planning processes, maintenance and operations, on mobile services, subscribers with major changes in their data consumption and generation behaviours, as well as on devices itself, with a myriad of different equipment communicating over such networks. Post 5G will be characterized by a profound transformation of several aspects: processes, technology, economic, social, but also environmental aspects, with energy efficiency and carbon neutrality playing an important role. It will represent a network of networks: where different types of access networks will coexist, an increasing diversity of devices of different nature, massive cloud computing utilization and subscribers with unprecedented data-consuming behaviours. All at greater throughput and quality of service, as unseen in previous generations.
The present research work uses 5G new radio (NR) latest release as baseline for developing the research activities, with future networks post 5G NR in focus. Two approaches were followed: i) method re-engineering, to propose new mechanisms and overcome existing or predictably existing limitations and ii) concept design and innovation, to propose and present innovative methods or mechanisms to enhance and improve the design, planning, operation, maintenance and optimization of 5G networks. Four main research areas were addressed, focusing on optimization and enhancement of 5G NR future networks, the usage of edge virtualized functions, subscriber’s behavior towards the generation of data and a carbon sequestering model aiming to achieve carbon neutrality. Several contributions have been made and demonstrated, either through models of methodologies that will, on each of the research areas, provide significant improvements and enhancements from the planning phase to the operational phase, always focusing on optimizing resource management. All the contributions are retro compatible with 5G NR and can also be applied to what starts being foreseen as future mobile networks. From the subscriber’s perspective and the ultimate goal of providing the best quality of experience possible, still considering the mobile network operator’s (MNO) perspective, the different proposed or developed approaches resulted in optimization methods for the numerous problems identified throughout the work. Overall, all of such contributed individually but aggregately as a whole to improve and enhance globally future mobile networks. Therefore, an answer to the main question was provided: how to further optimize a next-generation network - developed with optimization in mind - making it even more efficient while, simultaneously, becoming neutral concerning carbon emissions. The developed model for MNOs which aimed to achieve carbon neutrality through CO2 sequestration together with the subscriber’s behaviour model - topics still not deeply focused nowadays – are two of the main contributions of this thesis and of utmost importance for post-5G networks.Nos prĂłximos anos espera-se que as redes de comunicações mĂłveis se reinventem para lá da 5ÂŞ Geração (5G), com impactos profundos ao nĂvel da forma como sĂŁo planeadas, mantidas e operacionalizadas, ao nĂvel do comportamento dos subscritores de serviços mĂłveis, e atravĂ©s de uma mirĂade de dispositivos a comunicar atravĂ©s das mesmas. Estas redes serĂŁo profundamente transformadoras em termos tecnolĂłgicos, econĂłmicos, sociais, mas tambĂ©m ambientais, sendo a eficiĂŞncia energĂ©tica e a neutralidade carbĂłnica aspetos que sofrem uma profunda melhoria. Paradoxalmente, numa rede em que coexistirĂŁo diferentes tipos de redes de acesso, mais dispositivos, utilização massiva de sistema de computação em nuvem, e subscritores com comportamentos de consumo de serviços inĂ©ditos nas gerações anteriores. O trabalho desenvolvido utiliza como base a release mais recente das redes 5G NR (New Radio), sendo o principal focus as redes pĂłs-5G. Foi adotada uma abordagem de "reengenharia de mĂ©todos” (com o objetivo de propor mecanismos para resolver limitações existentes ou previsĂveis) e de “inovação e design de conceitos”, em que sĂŁo apresentadas tĂ©cnicas e metodologias inovadoras, com o principal objetivo de contribuir para um desenho e operação otimizadas desta geração de redes celulares.
Quatro grandes áreas de investigação foram endereçadas, contribuindo individualmente para um todo: melhorias e otimização generalizada de redes pós-5G, a utilização de virtualização de funções de rede, a análise comportamental dos subscritores no respeitante à geração e consumo de tráfego e finalmente, um modelo de sequestro de carbono com o objetivo de compensar as emissões produzidas por esse tipo de redes que se prevê ser massiva, almejando atingir a neutralidade carbónica. Como resultado deste trabalho, foram feitas e demonstradas várias contribuições, através de modelos ou metodologias, representando em cada área de investigação melhorias e otimizações, que, todas contribuindo para o mesmo objetivo, tiveram em consideração a retro compatibilidade e aplicabilidade ao que se prevê que sejam as futuras redes pós 5G.
Focando sempre na perspetiva do subscritor da melhor experiĂŞncia possĂvel, mas tambĂ©m no lado do operador de serviço mĂłvel – que pretende otimizar as suas redes, reduzir custos e maximizar o nĂvel de qualidade de serviço prestado - as diferentes abordagens que foram desenvolvidas ou propostas, tiveram como resultado a resolução ou otimização dos diferentes problemas identificados, contribuindo de forma agregada para a melhoria do sistema no seu todo, respondendo Ă questĂŁo principal de como otimizar ainda mais uma rede desenvolvida para ser extremamente eficiente, tornando-a, simultaneamente, neutra em termos de emissões de carbono. Das principais contribuições deste trabalho relevam-se precisamente o modelo de compensação das emissões de CO2, com vista Ă neutralidade carbĂłnica e um modelo de análise comportamental dos subscritores, dois temas ainda pouco explorados e extremamente importantes em contexto de redes futuras pĂłs-5G
Optimization of the methodology of configuration of mobile communication networks
The mobile communication network has been growing quickly, and the mobile network maintenance is becoming more complex, in performance, network coverage, energy, time consuming and expensive. The telecommunication service provider and mobile network telecommunication operator worries to what is the better methodology to optimizing a mobile network configuration and to improve the most efficient operation and functionality, to increase a superior performance in technical aspect (Create, and integrate new network planning in hardware and software level), economic aspect (cost reduction in maintenance) and environmental aspect (use of renewable energy through solar panels or wind power system).
The work developed in this dissertation aims to propose an optimization of methodology of configuration of mobile communication network and build an automated configuration system in different technology (GSM, UMTS and LTE) to provide a good quality and improvement in its architecture to meet the requirement for a large number of services or application through distinct means transmission and using technology appropriate with a new generation of hardware to reach certain area in a Base Station Transmition (BTS) and a Radio Network Controller (RNC) that permit configure and integrated hardware and software issues in distinct networks technology (GSM, UMTS and LTE).A rede de comunicação mĂłvel tem crescido rapidamente e ficando cada vez mais complexa, sendo cada vez mais complicado melhorar o desempenho, a cobertura, a eficiĂŞncia energĂ©tica e ao mesmo tempo aumentar o numero de utilizadores e serviços. O provedor de serviços de telecomunicações e a operadora de rede mĂłvel tĂŞm de se preocupar em optimizar de forma a garantir a melhor configuração de rede mĂłvel tendo em vista melhorar a operação e funcionalidade, a fim de esta ser mais eficiente, no seu desempenho. Relativamente aos aspectos tĂ©cnicos (Criar novo planeamento e integrar a uma rede ao nĂvel hardware e de software), aspecto econĂ´mico (redução de custo na manutenção) e aspecto ambiental (uso de energia renovável, quer atravĂ©s de painĂ©is solares como de sistemas eĂłlicos).
O trabalho desenvolvido nesta dissertação visa propor uma otimização da metodologia de configuração das redes de comunicação móveis e construir um sistema de configuração automatizado em diferentes tecnologias (GSM, UMTS e LTE), para garantir os mais altos padrões de qualidade e atender a exigência de um grande número de serviços ou aplicações através de diferentes meios de transmissão e uso de tecnologia apropriada com uma nova geração de hardware para atingir determinada área em uma Estação de Transmissão de Base (BTS) e numa Rede de Controlador de Rádio (RNC) que permitem configurar e integrar diversos tipos de hardware e software em tecnologia de diferentes redes (GSM, UMTS e LTE)
ENERGY BALANCED AND EFFICIENT CLUSTERING METHOD FOR WIRELESS SENSOR NETWORKS
In this paper the energy balanced and efficient clustering method based on balance of energy consumption of nodes in WSN is proposed, which may be applied to any WSN. The almost static centralized protocol that differs from previous methods is proposed, the main feature of which is that the sinks transmit most of control message and process most of data. First, EBEC method is proposed, which optimizes by considering energy consumption on transmitting and receiving data, energy consumption on the reclustering and hot-spot problem that be optimized individually in previous works. In order to implement this method, VW BAK-C algorithm is used by introducing the concept of variable weighted Euclid distance to k-clustering algorithm. Second, the previous clustering methods are classified into random method and the method based on QoS according to the characteristic of cluster head rotation, and average of total energy consumption of nodes is analyzed mathematically. The proposed method is compared and analyzed. Third, the performance of the proposed method is evaluated by comparing with other clustering methods through simulation
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