Dissertations / Theses on the topic 'Heterogenous Networks'
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Johansson, Klas. "Cost Effective Deployment Strategies for Heterogenous Wireless Networks." Doctoral thesis, KTH, Kommunikationssystem, CoS, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4563.
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Wireless access to the Internet is expected to be very valuable for both individuals and the society. However, advances in transmission technology alone may not be sufficient to support the anticipated demand for higher data rates and greater traffic volumes. Fortunately, a low cost means of increasing capacity is to match wireless infrastructures to the non-uniform spatial distribution of traffic. Multiple radio access standards and base station classes, having different cost and performance, could be combined to create a heterogeneous wireless access network which provides the required data rates and capacities where needed (or desired). In the case of a non-uniform spatial distribution of traffic, the traditional technical performance measures of coverage and capacity are no longer adequate for comparing the cost effectiveness of different network configurations. Therefore in this dissertation, we propose a general methodology to evaluate the total cost and capacity of heterogeneous networks. Moreover, a few promising capacity expansion paths, including multiple cellular standards as well as wireless local area network technologies, have been evaluated for urban scenarios. While results show that macro cellular systems are the most cost effective solution for a uniform spatial traffic distribution, a complementary hot spot layer is for non-uniform traffic distributions required even at a moderate average traffic density. The incremental cost, which is modest as compared to current revenues for operators, is shown to be quite insensitive to the choice of technology used in the hot spot layer. Moreover, if high data rates are demanded on the uplink, then dedicated indoor solutions are required. Which in turn implies that network providers should exploit existing broadband infrastructures to provide the required backhaul connectivity. In order to address non-urban scenarios, especially in sparsely populated areas, where there is insufficient revenue to support multiple independent networks, a multi-operator network sharing network architecture should be employed. This dissertation proposes a priority queuing method to achieve fair sharing of radio resources between operators in such an architecture.QC 20100730
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Nguyen, Viên. "The Trouble with Diversity: Fork-Join Networks with Heterogenous Customer Population." Massachusetts Institute of Technology, Operations Research Center, 1992. http://hdl.handle.net/1721.1/5406.
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Consider a feedforward network of single-server stations populated by multiple job types. Each job requires the completion of a number of tasks whose order of execution is determined by a set of deterministic precedence constraints. The precedence requirements allow some tasks to be done in parallel (in which case tasks would "fork") and require that others be processed sequentially (where tasks may "join"). Jobs of a. given type share the same precedence constraints, interarrival time distributions, and service time distributions, but these characteristics may vary across different job types. We show that the heavy traffic limit of certain processes associated with heterogeneous fork-join networks can be expressed as a semimartingale reflected Brownian motion with polyhedral state space. The polyhedral region typically has many more faces than its dimension, and the description of the state space becomes quite complicated in this setting. One can interpret the proliferation of additional faces in heterogeneous fork-join networks as (i) articulations of the fork and join constraints, and (ii) results of the disordering effects that occur when jobs fork and join in their sojourns through the network.
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Al-Yasir, Yasir, Ahmed M. Abdulkhaleq, Naser O. Parchin, Issa T. Elfergani, J. Rodriguez, James M. Noras, Raed A. Abd-Alhameed, A. Rayit, and Rami Qahwaji. "Green and Highly Efficient MIMO Transceiver System for 5G Heterogenous Networks." IEEE, 2021. http://hdl.handle.net/10454/18574.
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YesThe paper presents the general requirements and an exemplary design of the RF front-end system that in today´s handset is a key consumer of power. The design is required to minimize the carbon footprint in mobile handsets devices, whilst facilitating cooperation, and providing the energy-efficient operation of multi-standards for 5G communications. It provides the basis of hardware solutions for RF front-end integration challenges and offers design features covering energy efficiency for power amplifiers (PAs), Internet of Things (IoT) controlled tunable filters and compact highly isolated multiple-input and multiple-output (MIMO) antennas. An optimum design requires synergetic collaboration between academic institutions and industry in order to satisfy the key requirements of sub-6 GHz energy-efficient 5G transceivers, incorporating energy efficiency, good linearity and the potential for low-cost manufacturing. A highly integrated RF transceiver was designed and implemented to transmit and receive a picture using compact MIMO antennas integrated with efficient tunable filters and high linearity PAs. The proposed system has achieved a bit error rate (BER) of less than 10-10 at a data rate of 600 Mb/s with a wireless communication distance of more than 1 meter and power dissipation of 18-20 mW using hybrid beamforming technology and 64-QAM modulation.
10.13039/100010665-H2020 Marie Skodowska Curie
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Al-Yasir, Yasir I. A., Ahmed M. Abdulkhaleq, Naser O. Parchin, I. T. Elfergani, J. Rodriguez, James M. Noras, Raed A. Abd-Alhameed, A. Rayit, and Rami Qahwaji. "Green and Highly Efficient MIMO Transceiver System for 5G Heterogenous Networks." IEEE, 2007. http://hdl.handle.net/10454/18574.
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YesThe paper presents the general requirements and an exemplary design of the RF front-end system that in today´s handset is a key consumer of power. The design is required to minimize the carbon footprint in mobile handsets devices, whilst facilitating cooperation, and providing the energy-efficient operation of multi-standards for 5G communications. It provides the basis of hardware solutions for RF front-end integration challenges and offers design features covering energy efficiency for power amplifiers (PAs), Internet of Things (IoT) controlled tunable filters and compact highly isolated multiple-input and multiple-output (MIMO) antennas. An optimum design requires synergetic collaboration between academic institutions and industry in order to satisfy the key requirements of sub-6 GHz energy-efficient 5G transceivers, incorporating energy efficiency, good linearity and the potential for low-cost manufacturing. A highly integrated RF transceiver was designed and implemented to transmit and receive a picture using compact MIMO antennas integrated with efficient tunable filters and high linearity PAs. The proposed system has achieved a bit error rate (BER) of less than 10-10 at a data rate of 600 Mb/s with a wireless communication distance of more than 1 meter and power dissipation of 18-20 mW using hybrid beamforming technology and 64-QAM modulation.
10.13039/100010665-H2020 Marie Skodowska Curie
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Al-Yasir, Yasir, Ahmed M. Abdulkhaleq, Naser O. Parchin, I. T. Elfergani, J. Rodriguez, James M. Noras, Raed A. Abd-Alhameed, A. Rayit, and Rami Qahwaji. "Green and Highly Efficient MIMO Transceiver System for 5G Heterogenous Networks." IEEE, 2021. http://hdl.handle.net/10454/18574.
Full textAbstract:
YesThe paper presents the general requirements and an exemplary design of the RF front-end system that in today´s handset is a key consumer of power. The design is required to minimize the carbon footprint in mobile handsets devices, whilst facilitating cooperation, and providing the energy-efficient operation of multi-standards for 5G communications. It provides the basis of hardware solutions for RF front-end integration challenges and offers design features covering energy efficiency for power amplifiers (PAs), Internet of Things (IoT) controlled tunable filters and compact highly isolated multiple-input and multiple-output (MIMO) antennas. An optimum design requires synergetic collaboration between academic institutions and industry in order to satisfy the key requirements of sub-6 GHz energy-efficient 5G transceivers, incorporating energy efficiency, good linearity and the potential for low-cost manufacturing. A highly integrated RF transceiver was designed and implemented to transmit and receive a picture using compact MIMO antennas integrated with efficient tunable filters and high linearity PAs. The proposed system has achieved a bit error rate (BER) of less than 10-10 at a data rate of 600 Mb/s with a wireless communication distance of more than 1 meter and power dissipation of 18-20 mW using hybrid beamforming technology and 64-QAM modulation.
10.13039/100010665-H2020 Marie Skodowska Curie
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Detamore, Mathias J. "Paradox and the city a margin for the heterogenous connection of urban networks /." Cincinnati, Ohio : University of Cincinnati, 2005. http://www.ohiolink.edu/etd/view.cgi?acc%5Fnum=ucin1116214501.
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Thesis (Master of Architecture)--University of Cincinnati, 2005.Title from electronic thesis title page (viewed Jul. 10, 2006). Includes abstract. Keywords: Left-over urban space; paradox; margin; Thirdspace; Connection; Mobility; Heterogeneous; Space; Network. Includes bibliographical references.
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Chan, Siu-Yuen. "Efficent user level infrastructure support for adaptive parallel computing on heterogenous networks of workstations." Thesis, Queensland University of Technology, 2000.
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Sun, Chang. "Scalability Analysis of Synchronous Data-Parallel Artificial Neural Network (ANN) Learners." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/85020.
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Artificial Neural Networks (ANNs) have been established as one of the most important algorithmic tools in the Machine Learning (ML) toolbox over the past few decades. ANNs' recent rise to widespread acceptance can be attributed to two developments: (1) the availability of large-scale training and testing datasets; and (2) the availability of new computer architectures for which ANN implementations are orders of magnitude more efficient. In this thesis, I present research on two aspects of the second development. First, I present a portable, open source implementation of ANNs in OpenCL and MPI. Second, I present performance and scaling models for ANN algorithms on state-of-the-art Graphics Processing Unit (GPU) based parallel compute clusters.Master of Science
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Xu, Yiran. "Quality of Experience Aware Spectrum Efficiency and Energy Efficiency Over Wireless Heterogeneous Networks." DigitalCommons@USU, 2016. https://digitalcommons.usu.edu/etd/4664.
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Propelled by the explosive increases in mobile data traffic volume, existing wireless technologies are stretched to their capacity limits. There is a tremendous need for an expansion in system capacity and an improvement on energy efficiency. In addition, wireless network will support more and more multimedia services and applications, in which user experience has been always an important factor in evaluating the overall network performance. In order to keep pace with this explosion of data traffic and to meet the emerging quality of experience needs, wireless heterogeneous networks have been introduced as a promising network architecture evolution of the traditional cellular network.
In this dissertation, we explore video quality-aware spectrum efficiency and energy efficiency in wireless heterogeneous networks|the potentials and the associated technical challenges. In particular, aiming to significantly enhance spectrum efficiency, we need to tackle the interference issue, which is exacerbated in heterogeneous network due to ultra dense node deployment as well as heterogeneity nature of various nodes. Specifically, werst study an optimal intra-cell inter-tier cooperation to mitigate interference between high power nodes and low power nodes. Together with cooperation, optimal mobile association and resource allocation schemes are also intensively investigated in heterogeneous network to achieve system load balancing so that bandwidth at high power and low power nodes can be utilized in the optimal way. The proposed scheme can greatly alleviate inter-tier interference and significantly increase overall system spectrum efficiency in a heterogeneous network. We then further apply advanced algorithms such as precoding, and non-orthogonal multiple access into intra-cell inter-tier cooperation so that the overall system spectrum efficiency and user experience are even more improved. When supporting a video type application in such a heterogeneous network, considering only spectrum efficiency is far from enough as video application is bandwidth consuming, battery consuming, and quality demanding. We develop a video quality-aware spectrum and energy efficiency resource allocation scheme in a wireless heterogeneous network and propose novel performance metrics to establish fundamental relationships among spectrum efficiency, energy efficiency, and quality of experience. Extensive simulations are conducted to evaluate the trade-o performance among three performance metrics.
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Alkhawlani, Mohammed Mohssen. "Access network selection in heterogeneous networks." Thesis, De Montfort University, 2008. http://hdl.handle.net/2086/5217.
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The future Heterogeneous Wireless Network (HWN) is composed of multiple Radio Access Technologies (RATs), therefore new Radio Resource Management (RRM) schemes and mechanisms are necessary to benefit from the individual characteristics of each RAT and to exploit the gain resulting from jointly considering the whole set of the available radio resources in each RAT. These new RRM schemes have to support mobile users who can access more than one RAT alternatively or simultaneously using a multi-mode terminal. An important RRM consideration for overall HWN stability, resource utilization, user satisfaction, and Quality of Service (QoS) provisioning is the selection of the most optimal and promising Access Network (AN) for a new service request. The RRM mechanism that is responsible for selecting the most optimal and promising AN for a new service request in the HWN is called the initial Access Network Selection (ANS). This thesis explores the issue of ANS in the HWN. Several ANS solutions that attempt to increase the user satisfaction, the operator benefits, and the QoS are designed, implemented, and evaluated. The thesis first presents a comprehensive foundation for the initial ANS in the H\VN. Then, the thesis analyses and develops a generic framework for solving the ANS problem and any other similar optimized selection problem. The advantages and strengths of the developed framework are discussed. Combined Fuzzy Logic (FL), Multiple Criteria Decision Making (MCDM) and Genetic Algorithms (GA) are used to give the developed framework the required scalability, flexibility, and simplicity. The developed framework is used to present and design several novel ANS algorithms that consider the user, the operator, and the QoS view points. Different numbers of RATs, MCDM tools, and FL inference system types are used in each algorithm. A suitable simulation models over the HWN with a new set of performance evolution metrics for the ANS solution are designed and implemented. The simulation results show that the new algorithms have better and more robust performance over the random, the service type, and the terminal speed based selection algorithms that are used as reference algorithms. Our novel algorithms outperform the reference algorithms in- terms of the percentage of the satisfied users who are assigned to the network of their preferences and the percentage of the users who are assigned to networks with stronger signal strength. The new algorithms maximize the operator benefits by saving the high cost network resources and utilizing the usage of the low cost network resources. Usually better results are achieved by assigning the weights using the GA optional component in the implemented algorithms.
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Hildebrand, Matthias. "Optimized network access in heterogeneous wireless networks." Kassel : Kassel Univ. Press, 2005. http://deposit.d-nb.de/cgi-bin/dokserv?idn=977677540.
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Taiwo, Olugbenga Adekunle. "Network access selection in heterogeneous wireless networks." Master's thesis, University of Cape Town, 2013. http://hdl.handle.net/11427/16832.
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In heterogeneous wireless networks (HWNs), both single-homed and multi-homed terminals are supported to provide connectivity to users. A multiservice single-homed multi-mode terminal can support multiple types of services, such as voice call, file download and video streaming simultaneously on any one of the available radio access technologies (RATs) such as Wireless Local Area Network (WLAN), and Long Term Evolution (LTE). Consequently, a single-homed multi-mode terminal having multiple on-going calls may need to perform a vertical handover from one RAT to another. One of the major issues in HWNs is how to select the most suitable RAT for multiple handoff calls, and the selection of a suitable RAT for multiple-calls from a single-homed multi-mode terminal in HWNs is a group decision problem. This is because a single-homed multi-mode terminal can connect to only one RAT at a time, and therefore multiple handoff calls from the terminal have to be handed over to the same RAT. In making group decision for multiple-calls, the quality of service (QoS) requirements for individual calls needs to be considered. Thus, the RAT that most satisfies the QoS requirements of individual calls is selected as the most suitable RAT for the multiple-calls. Whereas most research efforts in HWNs have concentrated on developing vertical handoff decision schemes for a single call from a multi-mode terminal, not much has been reported in the literature on RAT-selection for multiple-calls from a single-homed multi-mode terminal in next generation wireless networks (NGWNs). In addition, not much has been done to investigate the sensitivity of RAT-selection criteria for multiple-calls in NGWNs. Therefore, this dissertation addresses these issues by focusing on following two main aspects: (1) comparative analysis of four candidate multi-criteria group decision-making (MCGDM) schemes that could be adapted for making RAT-selection decisions for multiple-calls, and (2) development of a new RAT-selection scheme named the consensus RAT-selection model. In comparative analysis of the candidate RAT-selection schemes, four MCGDM schemes namely: distance to the ideal alternative-group decision making (DIA-GDM), multiplicative exponent weighting-group decision making (MEW-GDM), simply additive weighting-group decision making (SAW-GDM), technique for order preference by similarity to Ideal solution-group decision making (TOPSIS-GDM) are considered. The performance of the multiple-calls RAT-selection schemes is evaluated using the MATLAB simulation tool. The results show that DIA-GDM and TOPSIS-GDM schemes are more suitable for multiple handoff calls than SAW-GDM and MEW-GDM schemes. This is because they are consistent and less-sensitive in making RAT-selection decision than the other two schemes, with regards to RAT-selection criteria (service price, data rate, security, battery power consumption and network delay) in HWNs. In addition, the newly developed RAT-selection scheme incorporates RAT-consensus level for improving RAT-selection decisions for multiple-calls. Numerical results conducted in MATLAB validate the effectiveness and performance of the newly proposed RAT-selection scheme for multiple-calls in HWNs.
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Cheng, Jerry. "Collaborative network security for heterogeneous mobile networks." Diss., Restricted to subscribing institutions, 2007. http://proquest.umi.com/pqdweb?did=1472132471&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Hildebrand, Matthias [Verfasser]. "Optimized network access in heterogeneous wireless networks / Matthias Hildebrand." Kassel : Kassel Univ. Press, 2005. http://d-nb.info/977677540/34.
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Behjati, Mohammadreza. "Self-organising network management for heterogeneous LTE-advanced networks." Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/10972.
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Since 2004, when the Long Term Evolution (LTE) was first proposed to be publicly available in the year 2009, a plethora of new characteristics, techniques and applications have been constantly enhancing it since its first release, over the past decade. As a result, the research aims for LTE-Advanced (LTE-A) have been released to create a ubiquitous and supportive network for mobile users. The incorporation of heterogeneous networks (HetNets) has been proposed as one of the main enhancements of LTE-A systems over the existing LTE releases, by proposing the deployment of small-cell applications, such as femtocells, to provide more coverage and quality of service (QoS) within the network, whilst also reducing capital expenditure. These principal advantages can be obtained at the cost of new challenges such as inter-cell interference, which occurs when different network applications share the same frequency channel in the network. In this thesis, the main challenges of HetNets in LTE-A platform have been addressed and novel solutions are proposed by using self-organising network (SON) management approaches, which allows the cooperative cellular systems to observe, decide and amend their ongoing operation based on network conditions. The novel SON algorithms are modelled and simulated in OPNET modeler simulation software for the three processes of resource allocation, mobility management and interference coordination in multi-tier macro-femto networks. Different channel allocation methods based on cooperative transmission, frequency reuse and dynamic spectrum access are investigated and a novel SON sub-channel allocation method is proposed based on hybrid fractional frequency reuse (HFFR) scheme to provide dynamic resource allocation between macrocells and femtocells, while avoiding co-tier and cross-tier interference. Mobility management is also addressed as another important issue in HetNets, especially in hand-ins from macrocell to femtocell base stations. The existing research considers a limited number of methods for handover optimisation, such as signal strength and call admission control (CAC) to avoid unnecessary handovers, while our novel SON handover management method implements a comprehensive algorithm that performs sensing process, as well as resource availability and user residence checks to initiate the handover process at the optimal time. In addition to this, the novel femto over macro priority (FoMP) check in this process also gives the femtocell target nodes priority over the congested macrocells in order to improve the QoS at both the network tiers. Inter-cell interference, as the key challenge of HetNets, is also investigated by research on the existing time-domain, frequency-domain and power control methods. A novel SON interference mitigation algorithm is proposed, which is based on enhanced inter-cell interference coordination (eICIC) with power control process. The 3-phase power control algorithm contains signal to interference plus noise ratio (SINR) measurements, channel quality indicator (CQI) mapping and transmission power amendments to avoid the occurrence of interference due to the effects of high transmission power. The results of this research confirm that if heterogeneous systems are backed-up with SON management strategies, not only can improve the network capacity and QoS, but also the new network challenges such as inter-cell interference can also be mitigated in new releases of LTE-A network.
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Li, Yue. "Edge computing-based access network selection for heterogeneous wireless networks." Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1S042/document.
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Au cours de ces dernières décennies, les réseaux de télécommunications mobiles ont évolué de la 1G à la 4G. La 4G permet la coexistence de différents réseaux d'accès. Ainsi, les utilisateurs ont la capacité de se connecter à un réseau hétérogène, constitué de plusieurs réseaux d'accès. Toutefois, la sélection du réseau approprié n'est pas une tâche facile pour les utilisateurs mobiles puisque les conditions de chaque réseau d'accès changent rapidement. Par ailleurs, en termes d'usage, le streaming vidéo devient le service principal de transfert de données sur les réseaux mobiles, ce qui amène les fournisseurs de contenu et les opérateurs de réseau à coopérer pour garantir la qualité de la diffusion. Dans ce contexte, la thèse propose la conception d'une approche novatrice pour la prise de décision optimale de sélection de réseau et une architecture améliorant les performances des services de streaming adaptatif dans un réseau hétérogène. En premier lieu, nous introduisons un modèle analytique décrivant la procédure de sélection de réseau en ne considérant déjà qu'une seule classe de trafic. Nous concevons ensuite une stratégie de sélection basée sur des fondements de la théorie du contrôle optimal linéaire. Des simulations sous MATLAB sont effectuées pour valider l'efficacité du mécanisme proposé. Sur ce même principe, nous étendons ce modèle avec un modèle analytique général décrivant les procédures de sélection de réseau dans des environnements de réseaux hétérogènes avec de multiples classes de trafic. Le modèle proposé est ensuite utilisé pour dériver un mécanisme adaptatif basé sur la théorie du contrôle, qui permet non seulement d'aider à piloter dynamiquement le trafic vers l'accès réseau le plus approprié mais aussi de bloquer dynamiquement le trafic résiduel lorsque le réseau est congestionné en ajustant les probabilités d'accès optimales. Nous discutons aussi les avantages d'une intégration transparente du mécanisme proposé avec l'ANDSF, solution fonctionnelle normalisée pour la sélection de réseau. Un prototype est également implémenté dans ns-3. En second lieu, nous nous concentrons sur l'amélioration des performances de DASH pour les utilisateurs mobiles dans un environnement de réseau d'accès 4G uniquement. Nous introduisons une nouvelle architecture basée sur l'utilisation de serveurs distribués en périphérie de réseau suivant le standard MEC. Le mécanisme d'adaptation proposé, fonctionnant en tant que service MEC, peut modifier les fichiers de manifeste en temps réel, en réponse à la congestion du réseau et à la demande dynamique de flux de streaming. Ces modifications conduisent ainsi les clients à sélectionner des représentations vidéo de débit / qualité plus appropriées. Nous avons développé une plateforme de test virtualisée pour l'expérimentation de notre proposition. Les résultats ainsi obtenus démontrent ses avantages en terme de QoE comparés aux approches d'adaptation traditionnelles, purement pilotées par les clients, car notre approche améliore non seulement le MOS mais aussi l'équité face à la congestion. Enfin, nous étendons l'architecture proposée basée sur MEC pour supporter le service de streaming adaptatif DASH dans un réseau hétérogène multi-accès afin de maximiser la QoE et l'équité des utilisateurs mobiles. Dans ce scénario, notre mécanisme doit aider les utilisateurs à sélectionner la qualité vidéo et le réseau et nous le formulons comme un problème d'optimisation. Ce problème d'optimisation peut être résolu par l'outil IBM CPLEX, mais cela prend du temps et ne peut être envisagé à grande échelle. Par conséquent, nous introduisons une heuristique pour aborder la solution optimale avec moins de complexité. Ensuite, nous mettons en œuvre une expérimentation sur notre plateforme de tests. Le résultat démontre que, par rapport à l'outil IBM CPLEX, notre algorithme permet d'obtenir des performances similaires sur la QoE globale et l'équité, avec un gain de temps significatifTelecommunication network has evolved from 1G to 4G in the past decades. One of the typical characteristics of the 4G network is the coexistence of heterogeneous radio access technologies, which offers end-users the capability to connect them and to switch between them with their mobile devices of the new generation. However, selecting the right network is not an easy task for mobile users since access network condition changes rapidly. Moreover, video streaming is becoming the major data service over the mobile network where content providers and network operators should cooperate to guarantee the quality of video delivery. In order to cope with this context, the thesis concerns the design of a novel approach for making an optimal network selection decision and architecture for improving the performance of adaptive streaming in the context of a heterogeneous network. Firstly, we introduce an analytical model (i.e. linear discrete-time system) to describe the network selection procedure considering one traffic class. Then, we consider the design of a selection strategy based on foundations from linear optimal control theory, with the objective to maximize network resource utilization while meeting the constraints of the supported services. Computer simulations with MATLAB are carried out to validate the efficiency of the proposed mechanism. Based on the same principal we extend this model with a general analytical model describing the network selection procedures in heterogeneous network environments with multiple traffic classes. The proposed model was, then, used to derive a scalable mechanism based on control theory, which allows not only to assist in steering dynamically the traffic to the most appropriate network access but also helps in blocking the residual traffic dynamically when the network is congested by adjusting dynamically the access probabilities. We discuss the advantages of a seamless integration with the ANDSF. A prototype is also implemented into ns-3. Simulation results sort out that the proposed scheme prevents the network congestion and demonstrates the effectiveness of the controller design, which can maximize the network resources allocation by converging the network workload to the targeted network occupancy. Thereafter, we focus on enhancing the performance of DASH in a mobile network environment for the users which has one access network. We introduce a novel architecture based on MEC. The proposed adaptation mechanism, running as an MEC service, can modify the manifest files in real time, responding to network congestion and dynamic demand, thus driving clients towards selecting more appropriate quality/bitrate video representations. We have developed a virtualized testbed to run the experiment with our proposed scheme. The simulation results demonstrate its QoE benefits compared to traditional, purely client-driven, bitrate adaptation approaches since our scheme notably improves both on the achieved MOS and on fairness in the face of congestion. Finally, we extend the proposed the MEC-based architecture to support the DASH service in a multi-access heterogeneous network in order to maximize the QoE and fairness of mobile users. In this scenario, our scheme should help users select both video quality and access network and we formulate it as an optimization problem. This optimization problem can be solved by IBM CPLEX tool. However, this tool is time-consuming and not scalable. Therefore, we introduce a heuristic algorithm to make a sub-optimal solution with less complexity. Then we implement a testbed to conduct the experiment and the result demonstrates that our proposed algorithm notably can achieve similar performance on overall achieved QoE and fairness with much more time-saving compared to the IBM CPLEX tool
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Kozat, Ulaș C. "Heterogeneous wireless networks : an analysis of network and service level diversity /." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1404.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2004.Thesis research directed by: Electrical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Wang, Xiaoyuan. "Network Selection and Rate Allocation in Heterogeneous Wireless Networks and Systems." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1258729392.
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Chung, Haera. "Optimal Network Topologies and Resource Mappings for Heterogeneous Networks-on-Chip." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/997.
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Communication has become a bottleneck for modern microprocessors and multi-core chips because metal wires don't scale. The problem becomes worse as the number of components increases and chips become bigger. Traditional Systems-on-Chips (SoCs) interconnect architectures are based on shared-bus communication, which can carry only one communication transaction at a time. This limits the communication bandwidth and scalability. Networks-on-Chip (NoC) were proposed as a promising solution for designing large and complex SoCs. The NoC paradigm provides better scalability and reusability for future SoCs, however, long-distance multi-hop communication through traditional metal wires suffers from both high latency and power consumption. A radical solution to address this challenge is to add long-range, low power, and high-bandwidth single-hop links between distant cores. The use of optical or on-chip RF wireless links has been explored in this context. However, all previous work has focused on regular mesh-based metal wire fabrics that were expanded with one or two additional link types only for long-distance communication.
In this thesis we address the following main research questions to address the above-mentioned challenges: (1) What library of different link types would represent an optimum in the design space? (2) How would these links be used to design an application-specific NoC architecture? (3) How would applications use the resulting NoC architecture efficiently? We hypothesize that networks with a higher degree of heterogeneity, i.e., three or more link types, will improve the network throughput and consume less energy compared to traditional NoC architectures. In order to verify our hypothesis and to address the research challenges, we design and analyze optimal heterogeneous networks under different realistic traffic models by considering different cost and performance trade-offs in a comprehensive technology-agnostic simulation framework that uses metaheuristic optimization techniques. As opposed to related work, our heterogeneous links can be placed anywhere in the network, which allows to explore the entire search space. The resulting application-specific networks are then analyzed by using complex network techniques, such as community detection and small-worldness, to understand how heterogeneous link types are used to improve the NoCs performance and cost. Next, we use the application-specific networks as a target architecture for other applications. The goal is to evaluate the performance of our new NoCs for applications they have not been designed for by finding optimal resource allocations.
Our results show that there is an optimal number of heterogeneous link types for each set of constraints and that networks with three or more heterogeneous link types provide significantly higher throughput along with lower energy consumption compared to both homogeneous link type and regular 2D mesh networks under three different traffic scenarios. Our evolved networks with three different technology-driven link types, namely metal wires, wireless, and optical links, provide 15% more throughput and fourteen times less energy consumption compared to homogeneous link type network. When ten different abstract link types are used in the design, 12% more throughput and 52% less energy consumption are obtained compared to networks with three different technology-driven link types. This shows that heterogeneous NoC designs based on traditional metal wires, wireless, and optical links, occupy a non-optimal spot in the entire design space. Our results further show that heterogeneous NoCs scale up significantly better in terms of performance and cost compared to mesh networks. We uncovered that network communities evolve robustly and that heterogeneous link types are efficiently establishing inter- and intra-subnet connections depending on their link type properties. We also show that mapping an application on our application-specific NoC architecture provides on average 45% more throughput at 70% less energy consumption compared to regular 2D mesh networks. The NoCs are therefore not only good for the application they were designed for, but for a broad range of other applications as well.
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Gambetti, Claudio <1978>. "Wireless heterogeneous networks." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/394/.
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Muhammad, Sanusi. "Scalable and network aware video coding for advanced communications over heterogeneous networks." Thesis, Brunel University, 2013. http://bura.brunel.ac.uk/handle/2438/7469.
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This work addresses the issues concerned with the provision of scalable video services over heterogeneous networks particularly with regards to dynamic adaptation and user’s acceptable quality of service. In order to provide and sustain an adaptive and network friendly multimedia communication service, a suite of techniques that achieved automatic scalability and adaptation are developed. These techniques are evaluated objectively and subjectively to assess the Quality of Service (QoS) provided to diverse users with variable constraints and dynamic resources. The research ensured the consideration of various levels of user acceptable QoS The techniques are further evaluated with view to establish their performance against state of the art scalable and non-scalable techniques. To further improve the adaptability of the designed techniques, several experiments and real time simulations are conducted with the aim of determining the optimum performance with various coding parameters and scenarios. The coding parameters and scenarios are evaluated and analyzed to determine their performance using various types of video content and formats. Several algorithms are developed to provide a dynamic adaptation of coding tools and parameters to specific video content type, format and bandwidth of transmission. Due to the nature of heterogeneous networks where channel conditions, terminals, users capabilities and preferences etc are unpredictably changing, hence limiting the adaptability of a specific technique adopted, a Dynamic Scalability Decision Making Algorithm (SADMA) is developed. The algorithm autonomously selects one of the designed scalability techniques basing its decision on the monitored and reported channel conditions. Experiments were conducted using a purpose-built heterogeneous network simulator and the network-aware selection of the scalability techniques is based on real time simulation results. A technique with a minimum delay, low bit-rate, low frame rate and low quality is adopted as a reactive measure to a predicted bad channel condition. If the use of the techniques is not favoured due to deteriorating channel conditions reported, a reduced layered stream or base layer is used. If the network status does not allow the use of the base layer, then the stream uses parameter identifiers with high efficiency to improve the scalability and adaptation of the video service. To further improve the flexibility and efficiency of the algorithm, a dynamic de-blocking filter and lambda value selection are analyzed and introduced in the algorithm. Various methods, interfaces and algorithms are defined for transcoding from one technique to another and extracting sub-streams when the network conditions do not allow for the transmission of the entire bit-stream.
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Ting, Kee Ngoh Alvin. "Network selection and optimisation of 4G heterogeneous multi-hop broadband wireless networks." Thesis, University of Strathclyde, 2014. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=24740.
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Wireless Heterogeneous Networking (HetNet) offers the potential to be one of the most promising approaches to meeting escalating network capacity demands cost-effectively. The main challenge facing the deployment of HetNets is provisioning backhaul connectivity for small cells and the selection is governed by availability and cost, not solely by capacity requirements. In practical deployments, the adoption of mixture of backhaul technologies is likely, creating a non-uniform capacity distribution of small cells. The challenge becomes even more demanding if the backhaul is in the form of a multi-hop network. The research therefore proposes two algorithms which ensure that users enjoy the best possible quality of experience represented in terms of connection throughput and fairness considering the issues owing to small cells backhauling. The performance of types of HetNet, the Hotspot Wireless HetNet (HWH) and Multi-hop Wireless HetNet (MWH) corresponding to direct and multi-hop backhauling of small cells is evaluated. For HWH, an algorithm - the Dynamic Backhaul Capacity Sensitive Network Selection Scheme (DyBaCS) - is developed to manage the non-uniform backhaul capacity distribution ensuring a consistently fair network bandwidth distribution whilst maintaining throughput. The performance of DyBaCS and two other commonly used network selection schemes (NSSs) is evaluated and compared. Results show that DyBaCS provides superior fairness and a user throughput performance comparable to other reported schemes. For the more complex MWH architecture, a joint Multi-hop Bandwidth Allocation (MBA) and DyBaCS algorithm is developed to manage network performance. The performance of the algorithm is compared to results obtained using the Cuckoo Search optimisation algorithm and the Fair Share bandwidth allocation scheme. Results show that the algorithm is resilient in improving cell throughput whilst maintaining high levels of fairness.
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Andersson, Karl. "On access network selection models and mobility support in heterogeneous wireless networks." Doctoral thesis, Luleå tekniska universitet, Datavetenskap, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-18402.
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The aim of this thesis is to define a solution offering end-users seamless mobility in a multi-radio access technology environment. Today an increasing portion of cell phones and PDAs have more than one radio access technology and wireless access networks of various types are commonly available with overlapping coverage. This creates a heterogeneous network environment in which mobile devices can use several networks in parallel. In such environment the device needs to select the best network for each application to use available networks wisely. Selecting the best network for individual applications constitutes a major core problem.The thesis proposes a host-based solution for access network selection in heterogeneous wireless networking environments. Host-based solutions use only information available in mobile devices and are independent of information available in the networks to which these devices are attached. The host-based decision mechanism proposed in this thesis takes a number of constraints into account including network characteristics and mobility patterns in terms of movement speed of the user. The thesis also proposes a solution for network-based mobility management contrasting the other proposals using a host-based approach. Finally, this thesis proposes an architecture supporting mobility for roaming users in heterogeneous environments avoiding the need for scanning the medium when performing vertical handovers.Results include reduced handover latencies achieved by allowing hosts to use multihoming, bandwidth savings on the wireless interface by removing the tunneling overhead, and handover guidance through the usage of directory-based solutions instead of scanning the medium. User-perceived quality of voice calls measured on the MOS (Mean Opinion Score) scale shows no or very little impact from the mobility support procedures proposed in this thesis. Results also include simulation models, real-world prototypes, and testbeds that all could be used in future work. The proposed solutions in this thesis are mainly evaluated using simulations and experiments with prototypes in live testbeds. Analytical methods are used to complement some results from simulations and experimentsGodkänd; 2010; 20100811 (karand); DISPUTATION Ämnesområde: Mobila system/Mobile Systems Opponent: Universitetslektor, docent Marcus Fiedler, Blekinge tekniska högskola Ordförande: Universitetslektor, docent Christer Åhlund, Luleå tekniska universitet Tid: Fredag den 12 november 2010, kl 11.00 Plats: A1514 Demostudion, Luleå tekniska universitet
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Magagula, Linoh A. "A network-based coordination design for seamless handover between heterogeneous wireless networks." Doctoral thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/10801.
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Includes bibliographical references (leaves 136-144).The rapid growth of mobile and wireless communication over the last few years has spawned many different wireless networks. These heterogeneous wireless networks are envisioned to interwork over an IP-based infrastructure to realize ubiquitous network service provisioning for mobile users. Moreover, the availability of multiple-interface mobile nodes (MNs) will make it possible to communicate through any of these wireless access networks. This wireless network heterogeneity combined with the availability of multiple-interface MNs creates an environment where handovers between the different wireless access technologies become topical during mobility events. Therefore, operators with multiple interworking heterogeneous wireless networks will need to facilitate seamless vertical handovers among their multiple systems. Seamless vertical handovers ensure ubiquitous continuity to active connections hence satisfy the quality of experience of the mobile users.
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Zhang, Jianjun. "Efficient Information Dissemination in Wide Area Heterogeneous Overlay Networks." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/16129.
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In this dissertation research we study and address the unique challenges involved in information sharing and dissemination of large-scale group communication applications. We focus on system architectures and various techniques for efficient and scalable information dissemination in distributed P2P environments. Our solutions are developed by targeting at utilizing three representative P2P overlay networks: structured P2P network based on consistent hashing techniques, unstructured Gnutella-like P2P network, and P2P GeoGrid based on geographical location and proximity of end nodes. We have made three unique contributions to the general field of large-scale information sharing and dissemination. First, we propose a landmark-based peer clustering techniques to grouping end-system nodes by their network proximity, and a communication management technique addresses load balancing and reliability of group communication applications in structured P2P network. Second, we develop a utility-based P2P group communication service middleware, consisting of a utility-based topology management and a utility-aware P2P routing, for providing scalable and efficient group communication services in an unstructured P2P overlay network of heterogeneous peers. Third, we propose an overlay network management protocol that is aware of the geographical location of end-system nodes and a set of routing and adaptation techniques, aiming at building decentralized information dissemination service networks to support location-based applications and services.
Although different overlay networks require different system designs for building scalable and efficient information dissemination services, we have employed two common design philosophies: (1) exploiting end-system heterogeneity and (2) utilizing proximity information of end-system nodes to localize most of the communication traffic, and (3) using randomized shortcuts to accelerate long-distant communications. We have demonstrated our design philosophies and the performance improvements in the above three types of P2P overlay networks. Concretely, by assigning more workloads to more powerful peers, we can greatly increase the system scalability and reduce the variation of workload distribution. By clustering end-system nodes based on their IP-network proximity or their geographical proximity, and utilizing randomized shortcuts, we can reduce the end-to-end communication latency, balance peer workloads against service request hotspots across the overlay network, and significantly enhance the scalability and efficiency of large-scale decentralized information dissemination and group communication.
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Mugume, Edwin. "Green heterogeneous cellular networks." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/green-heterogeneous-cellular-networks(e7976a91-c891-4174-abaf-18820ff1736d).html.
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Data traffic demand has been increasing exponentially and this trend will continue over theforeseeable future. This has forced operators to upgrade and densify their mobile networks toenhance their capacity. Future networks will be characterized by a dense deployment of different kinds of base stations (BSs) in a hierarchical cellular structure. However network densification requires extensive capital and operational investment which limits operator revenues and raises ecological concerns over greenhouse gas emissions. Although networks are planned to support peak traffic, traffic demand is actually highly variable in both space and time which makes it necessary to adapt network energy consumption to inevitable variations in traffic demand. In this thesis, stochastic geometry tools are used to perform simple and tractable analysis of thecoverage, rate and energy performance of homogeneous networks and heterogeneous networks(HetNets). BSs in each tier are located according to independent Poisson Point Processes(PPPs) to generate irregular topologies that fairly resemble practical deployment topologies. The homogeneous network is optimized to determine the optimal BS density and transmit power configuration that minimizes its area power consumption (APC) subject to both coverage and average rate constraints. Results show that optimal transmit power only depends on the BSpower consumption parameters and can be predetermined. Furthermore, various sleep modemechanisms are applied to the homogeneous network to adapt its APC to changes in userdensity. A centralized strategic scheme which prioritize BSs with the least number of usersenhances energy efficiency (EE) of the network. Due to the complexity of such a centralizedscheme, a distributed scheme which implements the strategic algorithm within clusters of BSsis proposed and its performance closely matches that of its centralized counterpart. It is more challenging to model the optimal deployment configuration per tier in a multi-tier HetNet. Appropriate assumptions are used to determine tight approximations of these deployment configurations that minimize the APC of biased and unbiased HetNets subject tocoverage and rate constraints. The optimization is performed for three different user associationschemes. Similar to the homogeneous network, optimal transmit power per tier also depends onBS power consumption parameters only and can also be predetermined. Analysis of the effect of biasing on HetNet performance shows appropriate biasing can further reduce the deploymentconfiguration (and consequently the APC) compared to an unbiased HetNet. In addition, biasing can be used to offload traffic from congesting and high-power macro BSs to low-power small BSs. If idle BSs are put into sleep mode, more energy is saved and HetNet EE improves. Moreover, appropriate biasing also enhances the EE of the HetNet.
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Sibanda, Clifford Clifton Leonard. "Media independent handovers : network selection for mobile IP nodes in heterogeneous wireless networks." Master's thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/5104.
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Includes abstract.Includes bibliographical references (p. 79-82).
In Next Generation Networks (NGN), also known as 4G, Beyond 3G, Converged, Integrated and Interworked Network, user node mobility in wireless and wired environments will seamlessly cross disparate network boundaries. The effort to offer ubiquitous computing, providing access to services anywhere and anytime, strongly encourages the ability to roam across the different existing and future networks. Literature shows investigation of concepts such as Always Best Connected (ABC) when heterogeneous networks co-exist , which will work or compete with other schemes like Home Network Default (HND), Compatibility and Network Operator Agreements (CNOA) to guide network selection or access . With the variety of available networks, the mobile node may be faced with having to decide which network to connect to. We concentrate on the network selection aspects of these envisaged mobile, overlay and integrated environment in heterogeneous networks. The standard developments by the IEEE802.21 Working group and the IETF Networking group form the base of our approach that seeks to see mobility across heterogeneous networks a reality. We propose an IEEE802.21 Media Independent Handover Function (MIHF) based network discovery and network selection, leading to a handover. The selection may be further assisted by an MIHF capable Broker Node that is Third party to the Network Providers to provide a central yet distributed database of the available networks as encountered by the Mobile Node, to cater for Nodes with no prior knowledge of networks and software repository. A Mobile Node (MN) in our solution uses 802.21 communication messages to obtain information about foreign networks encountered before selecting the networks to connect to. Our evaluation through simulations, shows that network selection in heterogeneous wireless networks environment for the appropriately equipped devices is greatly enhanced by the use of the Media Independent Handover Protocol. In scenarios where the mobile node has no prior knowledge of the encountered different network architectures, the use of a Broker node can, for an optimal number of available networks also greatly enhance the mobile node’s network selection by reducing the delay associated and the packet losses incurred.
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Khan, Shoaib. "Towards a reliable seamless mobility support in heterogeneous IP networks." Thesis, Brunel University, 2009. http://bura.brunel.ac.uk/handle/2438/4065.
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Next Generation networks (3G and beyond) are evolving towards all IP based systems with the aim to provide global coverage. For Mobility in IP based networks, Mobile IPv6 is considered as a standard by both industry and research community, but this mobility protocol has some reliability issues. There are a number of elements that can interrupt the communication between Mobile Node (MN) and Corresponding Node (CN), however the scope of this research is limited to the following issues only: • Reliability of Mobility Protocol • Home Agent Management • Handovers • Path failures between MN and CN First entity that can disrupt Mobile IPv6 based communication is the Mobility Anchor point itself, i.e. Home Agent. Reliability of Home Agent is addressed first because if this mobility agent is not reliable there would be no reliability of mobile communication. Next scenario where mobile communication can get disrupted is created by MN itself and it is due to its mobility. When a MN moves around, at some point it will be out of range of its active base station and at the same time it may enter the coverage area of another base station. In such a situation, the MN should perform a handover, which is a very slow process. This handover delay is reduced by introducing a “make before break” style handover in IP network. Another situation in which the Mobile IPv6 based communication can fail is when there is a path failure between MN and CN. This situation can be addressed by utilizing multiple interfaces of MN at the same time. One such protocol which can utilize multiple interfaces is SHIM6 but it was not designed to work on mobile node. It was designed for core networks but after some modification in the protocol , it can be deployed on mobile nodes. In this thesis, these issues related to reliability of IPv6 based mobile communication have been addressed.
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Al, Ridhawi Ismaeel. "Simulation-Assisted QoS-Aware VHO in Wireless Heterogeneous Networks." Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/30377.
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The main goal of today’s wireless Service Providers (SPs) is to provide optimum and ubiquitous service for roaming users while maximizing the SPs own monetary profits. The fundamental objective is to support such requirements by providing solutions that are adaptive to varying conditions in highly mobile and heterogeneous, as well as dynamically changing wireless network infrastructures. This can only be achieved through well-designed management systems. Most techniques fail to utilize the knowledge gained from previously tested reconfiguration strategies on system and network behaviour.
This dissertation presents a novel framework that automates the cooperation among a number of wireless SPs facing the challenge of meeting strict service demands for a large number of mobile users. The proposed work employs a novel policy-based system configuration model to automate the process of adapting new network policies. The proposed framework relies on the assistance of a real-time simulator that runs as a constant background process in order to continuously find optimal policy configurations for the SPs’ networks. To minimize the computational time needed to find these configurations, a modified tabu-search scheme is proposed. An objective is to efficiently explore the space of network configurations in order to find optimal network decisions and provide a service performance that adheres to contracted service level agreements.
This framework also relies on a distributed Quality of Service (QoS) monitoring scheme. The proposed scheme relies on the efficient identification of candidate QoS monitoring users that can efficiently submit QoS related measurements on behalf of their neighbors. These candidate users are chosen according to their devices’ residual power and transmission capabilities and their estimated remaining service lifetime. Service monitoring users are then selected from these candidates using a novel user-to-user semantic similarity matching algorithm. This step ensures that the monitoring users are reporting on behalf of other users that are highly similar to them in terms of their mobility, used services and device profiles.
Experimental results demonstrate the significant gains achieved in terms of the reduced traffic overhead and overall consumed users’ devices power while achieving a high monitoring accuracy, adaptation time speedup, base station load balancing, and individual providers’ payoffs.
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Yao, Yong. "A Software Framework for Prioritized Spectrum Access in Heterogeneous Cognitive Radio Networks." Doctoral thesis, Blekinge Tekniska Högskola [bth.se], Faculty of Computing - Department of Communication Systems, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-00590.
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Today, the radio spectrum is rarely fully utilized. This problem is valid in more domains, e.g., time, frequency and geographical location. To provide an efficient utilization of the radio spectrum, the Cognitive Radio Networks (CRNs) have been advanced. The key idea is to open up the licensed spectrum to unlicensed users, thus allowing them to use the so-called spectrum opportunities as long as they do not harmfully interfere with licensed users. An important focus is laid on the limitation of previously reported research efforts, which is due to the limited consideration of the problem of competition among unlicensed users for spectrum access in heterogeneous CRNs. A software framework is introduced, which is called PRioritized Opportunistic spectrum Access System (PROAS). In PROAS, the heterogeneity aspects of CRNs are specifically expressed in terms of cross-layer design and various wireless technologies. By considering factors like ease of implementation and efficiency of control, PROAS provides priority scheduling based solutions to alleviate the competition problem of unlicensed users in heterogenous CRNs. The advanced solutions include theoretical models, numerical analysis and experimental simulations for performance evaluation. By using PROAS, three particular CRN models are studied, which are based on ad-hoc, mesh-network and cellular-network technologies. The reported results show that PROAS has the ability to bridge the gap between research results and the practical implementation of CRNs.
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Zheng, Zici. "Adaptive explicit congestion notification (AECN) for heterogeneous flows." Link to electronic thesis, 2001. http://www.wpi.edu/Pubs/ETD/Available/etd-0502101-062544.
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Abou-Zeid, Al-Hussein A. "Stochastic models of congestion control in heterogeneous next generation packet networks /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/5994.
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Baranda, Hortigüela Jorge. "End-to-end network service orchestration in heterogeneous domains for next-generation mobile networks." Doctoral thesis, Universitat Politècnica de Catalunya, 2021. http://hdl.handle.net/10803/672782.
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5G marks the beginning of a deep revolution in the mobile network ecosystem, transitioning to a network of services to satisfy the demands of new players, the vertical industries. This revolution implies a redesign of the overall mobile network architecture where complexity, heterogeneity, dynamicity, and flexibility will be the rule. Under such context, automation and programmability are essential to support this vision and overcome current rigid network operation processes. Software Defined Networking (SDN), Network Function Virtualization (NFV) and Network slicing are key enabling techniques to provide such capabilities. They are complementary, but they are still in its infancy and the synergies between them must be exploited to realise the mentioned vision.
The aim of this thesis is to further contribute to its development and integration in next generation mobile networks by designing an end-to-end (E2E) network service orchestration (NSO) architecture, which aligned with some guidelines and specifications provided by main standardization bodies, goes beyond current management and orchestration (MANO) platforms to fulfil network service lifetime requirements in heterogeneous multi-technology/administrative network infrastructures shared by concurrent instances of diverse network services.
Following a bottom-up approach, we start studying some SDN aspects related to the management of wireless network elements and its integration into hierarchical control architectures orchestrating networking resources in a multi-technology (wireless, optical, packet) infrastructure. Then, this work is integrated in an infrastructure manager module executing the joint resource abstraction and allocation of network and compute resources in distributed points of presence (PoPs) connected by a transport network, aspect which is not (or lightly) handled by current MANO platforms. This is the module where the integration between NFV and SDN techniques is executed. This integration is commanded by a Service Orchestrator module, in charge of automating the E2E lifecycle management of network services implementing network slices (NS) based on the vertical requirements, the available infrastructure resources, and, while fulfilling service level agreement (SLA) also during run-time operation. This architecture, focused on single administrative domain (AD) scenarios, constitutes the first group of contributions of this thesis.
The second group of contributions evolves this initial architecture to deal with the orchestration and sharing of NS and its network slice subnet instances (NSSIs) involving multiple ADs. The main differential aspect with current state-of-the-art solutions is the consideration of resource orchestration aspects during the whole orchestration process. This is fundamental to achieve the interconnection of NSSIs, hence making the E2E multi-domain orchestration and network slicing a reality in practice. Additionally, this work also considers SLA management aspects by means of scaling actions during run-time operation in such complex scenarios.
The third group of contributions demonstrate the validity and applicability of the resulting architectures, workflows, and interfaces by implementing and evaluating them in real experimental infrastructures featuring multiple ADs and transport technologies interconnecting distributed computing PoPs. The performed experimentation considers network service definitions close to real vertical use cases, namely automotive and eHealth, which help bridging the gap between network providers and vertical industries stakeholders. Experimental results show that network service creation and scaling times in the order of minutes can be achieved for single and multi-AD scenarios, in line with 5G network targets. Moreover, these measurements serve as a reference for benchmarking the different operations involved during the network service deployment. Such analysis are limited in current literature.5G marca el inicio de una gran revolución en las redes móviles, convirtiéndose en redes orientadas a servicios para satisfacer las demandas de nuevos actores, las industrias verticales. Esta revolución supone un rediseño total de la arquitectura de red donde la complejidad, heterogeneidad, dinamicidad y flexibilidad serán la norma. En este contexto, la automatización y programabilidad serán esenciales para superar los rígidos procesos actuales de operación de red. Las redes definidas por software (SDN), la virtualización de funciones de red (NFV) y el particionamiento de redes son técnicas clave para proporcionar dichas capacidades. Éstas son complementarias, pero aún recientes y sus sinergias se deben explotar para realizar la nueva visión. El objetivo de esta tesis es contribuir a su desarrollo e integración en la nuevas generaciones de redes móviles mediante el diseño de una arquitectura de orquestación de servicios de red (NSO) extremo a extremo (E2E), que alineada con algunas pautas y especificaciones de los principales organismos de estandarización, va más allá de los actuales sistemas de gestión y orquestación (MANO) para instanciar y garantizar los requisitos de los diversos servicios de red desplegados concurrentemente en infraestructuras heterogéneas compartidas que combinan múltiples tecnologías y dominios administrativos (AD). Siguiendo un enfoque ascendente, comenzamos a estudiar aspectos de SDN relacionados con la gestión de elementos de red inalámbricos y su integración en arquitecturas jerárquicas de orquestación de recursos de red en infraestructuras multi tecnología (inalámbrica, óptica, paquetes). Luego, este trabajo se integra en un módulo de administración de infraestructura que ejecuta de forma conjunta la abstracción y la asignación de recursos de red y computación en múltiples puntos de presencia (PoP) distribuidos conectados por una red de transporte, aspecto que no está (o ligeramente) considerado por los actuales sistemas MANO. Este módulo ejecuta la integración de las técnicas NFV y SDN. Esta integración está dirigida por el módulo Orquestador de Servicios, que automatiza la gestión E2E del ciclo de vida de los servicios de red implementando las diferentes particiones de red en base a los requisitos de los verticales, los recursos de infraestructura disponibles y mientras cumple los acuerdos de nivel de servicio (SLA) durante la operación del servicio. Esta arquitectura, centrada en escenarios con un único AD, forma el primer grupo de contribuciones de esta tesis. El segundo grupo de contribuciones evoluciona esta arquitectura abordando la orquestación y compartición de particiones de red y sus componentes (NSSIs) en escenarios con múltiples AD. La consideración detallada de aspectos de orquestación de recursos es el principal aspecto diferencial con la literatura. Esto es fundamental para la interconexión de NSSIs, haciendo realidad la orquestación E2E y el particionamiento de red en escenarios con múltiples AD. Además, se considera la gestión de SLA mediante acciones de escalado durante la operación del servicio en los escenarios mencionados. El tercer grupo de contribuciones valida las arquitecturas, procedimientos e interfaces resultantes pues se han implementado y evaluado sobre infraestructuras experimentales reales que presentan múltiples AD y tecnologías de transporte interconectando PoP distribuidos. Esta experimentación considera definiciones de servicios de red cercanos a casos de uso de verticales reales, como automoción y eHealth, ayudando a cubrir la brecha entre los proveedores de red y los verticales. Los resultados experimentales muestran que la creación y el escalado de servicios de red se pueden realizar en pocos minutos en escenarios con un único o múltiples ADs, en línea con los indicadores de red objetivos de 5G. Estas medidas, escasas en la literatura actual, sirven como referencia para caracterizar las diferentes operaciones involucradas durante el despliegue de servicios.
Arquitectura de computadors
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Shen, Wei. "Network Selection Strategies and Resource Management Schemes in Integrated Heterogeneous Wireless and Mobile Networks." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1250182019.
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CAVALCANTI, DAVE ALBERTO TAVARES. "INTEGRATED ARCHITECTURE AND ROUTING PROTOCOLS FOR HETEROGENEOUS WIRELESS NETWORKS." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1140716621.
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Grimm, Allen Gary. "An Exploration Of Heterogeneous Networks On Chip." PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/185.
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As the the number of cores on a single chip continue to grow, communication increasingly becomes the bottleneck to performance. Networks on Chips (NoC) is an interconnection paradigm showing promise to allow system size to increase while maintaining acceptable performance. One of the challenges of this paradigm is in constructing the network of inter-core connections. Using the traditional wire interconnect as long range links is proving insufficient due to the increase in relative delay as miniaturization progresses. Novel link types are capable of delivering single-hop long-range communication. We investigate the potential benefits of constructing networks with many link types applied to heterogeneous NoCs and hypothesize that a network with many link types available can achieve a higher performance at a given cost than its homogeneous network counterpart. To investigate NoCs with heterogeneous links, a multiobjective evolutionary algorithm is given a heterogeneous set of links and optimizes the number and placement of those links in an NoC using objectives of cost, throughput, and energy as a representative set of a NoC's quality. The types of links used and the topology of those links is explored as a consequence of the properties of available links and preference set on the objectives. As the platform of experimentation, the Complex Network Evolutionary Algorithm (CNEA) and the associated Complex Network Framework (CNF) are developed. CNEA is a multiobjective evolutionary algorithm built from the ParadisEO framework to facilitate the construction of optimized networks. CNF is designed and used to model and evaluate networks according to: cost of a given topology; performance in terms of a network's throughput and energy consumption; and graph-theory based metrics including average distance, degree-, length-, and link-distributions. It is shown that optimizing complex networks to cost as a function of total link length and average distance creates a power-law link-length distribution. This offers a way to decrease the average distance of a network for a given cost when compared to random networks or the standard mesh network. We then explore the use of several types of constrained-length links in the same optimization problem and find that, when given access to all link types, we obtain networks that have the same or smaller average distance for a given cost than any network that is produced when given access to only one link type. We then introduce traffic on the networks with an interconnect-based packet-level shortest-path-routed traffic model. We find heterogeneous networks can achieve a throughput as good or better than the homogeneous network counterpart using the same amount of link. Finally, these results are confirmed by augmenting a wire-based mesh network with non-traditional link types and finding significant increases the overall performance of that network.
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Benigni, Matthew Curran. "Detection and Analysis of Online Extremist Communities." Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/949.
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Online social networks have become a powerful venue for political activism. In many cases large, insular online communities form that have been shown to be powerful diffusion mechanisms of both misinformation and propaganda. In some cases these groups users advocate actions or policies that could be construed as extreme along nearly any distribution of opinion, and are thus called Online Extremist Communities (OECs). Although these communities appear increasingly common, little is known about how these groups form or the methods used to influence them. The work in this thesis provides researchers a methodological framework to study these groups by answering three critical research questions: How can we detect large dynamic online activist or extremist communities? What automated tools are used to build, isolate, and influence these communities? What methods can be used to gain novel insight into large online activist or extremist communities? These group members social ties can be inferred based on the various affordances offered by OSNs for group curation. By developing heterogeneous, annotated graph representations of user behavior I can efficiently extract online activist discussion cores using an ensemble of unsupervised machine learning methods. I call this technique Ensemble Agreement Clustering. Through manual inspection, these discussion cores can then often be used as training data to detect the larger community. I present a novel supervised learning algorithm called Multiplex Vertex Classification for network bipartition on heterogeneous, annotated graphs. This methodological pipeline has also proven useful for social botnet detection, and a study of large, complex social botnets used for propaganda dissemination is provided as well. Throughout this thesis I provide Twitter case studies including communities focused on the Islamic State of Iraq and al-Sham (ISIS), the ongoing Syrian Revolution, the Euromaidan Movement in Ukraine, as well as the alt-Right.
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Liu, Xiaoshan. "Mobility and radio resource management in heterogeneous wireless networks." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B38233873.
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Pimentel, Niño Maria Alejandra. "Video adaptation over heterogeneous networks." Doctoral thesis, Universitat Autònoma de Barcelona, 2014. http://hdl.handle.net/10803/283931.
Full textAbstract:
Los servicios de video hoy en día hacen parte de nuestras interacciones cotidianas y aportan la mayor parte del tráfico en la red. Su uso más amplio incluye escenarios fuera de lo común como lo son la ayuda en emergencias o en telemedicina. Por otra parte, las demandas de los usuarios de tales servicios, en términos de experiencia usuario, sigue en aumento, llevando a requerimientos más especializados de Calidad de Experiencia ( QoE en ínglés). Garantizar cierto nivel de satisfacción de usuario en escenarios exigentes donde las redes a disposición son heterogéneas continua siendo in problema abierto.
Los objetivos principales de esta tesis han sido: 1) proponer un marco de trabajo para networking heterogéneo que permita la transmisión de video de manera impecable a través de redes heterogéneas, 2) proponer un marco centrado en el usuario, para transmitir video que sea coherente con el networking heterogéneo, y 3) diseñar un modelo y solución completos para ofrecer video adaptativo tal que se cumplan los requerimientos de satisfacción de usuario.
A continuación se presentan las contribuciones de esta tesis que cumplen los tres objetivos trazados.
Primero, proponemos modelar las redes heterogéneas desde un ángulo holístico. La metodología de este diseño holístico de sistema está basado en dos conceptos novedosos. En primer lugar, proveer un marco a través del cual las instancias de red pueden ser modeladas para garantizar generalidad y robustez. En segundo lugar, caracterizar de manera única las instancias de red a través de su min-cut. La ventaja de este marco es que puede verse como un modelo de sistema subyacente que garantiza una impecable transmisión de contenido sin importar la instancia de red. Esto es posible formulando una optimización cross-layer para transmisión de contenido, coherente con la filosofía de networking centrada en la información (information-centric networking).
Segundo, proponemos un marco para video adaptativo impulsado por el QoE, basado en una formulación de optimización cross-layer. El algoritmo resultante permite la adaptación de video y se basa en los retardos de redes variantes en el tiempo, por lo tanto tiene en cuenta las restricciones de redes con retardos largos y las dificultades de establecer un camino de retorno que permita la adaptabilidad a los cambios en la red. Esta solución se ha evaluado sistemáticamente, tanto en entornos emulados como en una solución complemente implementada experimentalmente.
Tercero, proponemos la contribución principal de esta tesis: un modelo completo centrado en el usuario, que ofrece servicios de video en redes heterogéneas. El problema de borrado de paquetes y de congestión en las redes sin garantías (best-effort) es desacoplado para así hacerlos coincidir con los efectos respectivos que degradan el video. Esto permite la formulación de dos problemas de optimización, en tiempo (fotogramas congelados) y espacio (artefactos en la imagen). La solución completa además una novedosa dimensión semántica coherente con information-centric networking, que propone reflejar las necesidades perceptuales del usuario final. Probamos las ventajas de nuestro diseño para escenarios donde el video es necesario para adquirir conciencia de situaciones (situation awareness), donde se usan comúnmente redes heterogéneas y mostramos ganancias considerables en términos de reducción de los efectos de la congestión y el borrado de paquetes, mientras que mejoramos el QoE y cumplimos las demandas perceptuales de los usuarios.Video services have become part of everyday interactions and contribute to a major portion of network traffic. Their broader usage includes out-of-the-ordinary scenarios as aid in emergencies, or telemedicine. Moreover, user demands of such services in terms of overall user experience continue to increase, leading to more specialized Quality of Experience (QoE) requirements. Guaranteeing a level of satisfaction to the user in challenging scenarios where the alternative networks are heterogeneous in nature continues to be an open issue. The main objectives of this thesis have been to: 1) propose a framework for heterogeneous networking that allows for a seamless delivery of video content along diverse heterogeneous networks, 2) propose a user-centric framework for video transmission in line with heterogeneous networking, and 3) design a complete model and solution to provide video adaptation in heterogeneous networks such that it meets the requirements for user satisfaction. The contributions of this thesis, such that the three objectives are met are as follows. First, we propose to model heterogeneous networks with a holistic approach. The methodology of this holistic system design is based on two novel concepts. On one hand, to provide a framework by which heterogeneous network instances can be modeled to guarantee generality and robustness. On the other hand, to uniquely characterize the network instances via their min-cut. The strength of this framework is its usage as an underlying system model that can guarantee seamless content delivery regardless of the network instance. The latter is possible by formulating a general cross-layer optimization for content delivery, coherent to information-centric networking philosophy. Second, we propose a QoE-driven adaptive video framework, based on a cross-layer optimization formulation. The derived adaptive video algorithm for time-variant networks is delay-driven, hence contemplates the constraints of long-delayed networks and the challenges of establishing a feedback loop to enable the network adaptability. The framework is evaluated systematically, in both an emulation and a fully implemented experimental environment. Third, we propose the main contribution of this thesis: a complete model to provide user-centric video services in heterogeneous networks. The problem of combined erasures and congestion in best effort network is decoupled to match the specific degrading effects on the video. This allows for two separate QoE driven optimization approaches in time (freezes) and space (artifacts) domain. The complete solution offers a feasible dynamic streaming adaptation that suits constraint heterogeneous networks such as satellite. The performance is evaluated through a novel QoE three-dimensional analysis. The overall solution contemplates a novel semantical dimension, in line with information-centric networking, with an unexplored take on semantics that intends to reflect on the perceptual needs of the end user. We prove the strength of our design for the situation awareness scenario, where heterogeneous networks are often used, and show substantial gain in terms of mitigation of the effects of congestion and erasures while improving QoE and achieving the expected user's perceptual demands.
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Sandberg, Henrik, Maben Rabi, Mikael Skoglund, and Karl Henrik Johansson. "Estimation over heterogeneous sensor networks." KTH, ACCESS Linnaeus Centre, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-30325.
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Design trade-offs between estimation performance, processing delay and communication cost for a sensor scheduling problem is discussed. We consider a heterogeneous sensor network with two types of sensors: the first type has low-quality measurements, small processing delay and a light communication cost, while the second type is of high quality, but imposes a large processing delay and a high communication cost. Such a heterogeneous sensor network is common in applications, where for instance in a localization system the poor sensor can be an ultrasound sensor while the more powerful sensor can be a camera. Using a time-periodic Kalman filter, we show how one can find an optimal schedule of the sensor communication. One can significantly improve estimation quality by only using the expensive sensor rarely. We also demonstrate how simple sensor switching rules based on the Riccati equation drives the filter into a stable time-periodic Kalman filter. ￜ 2008 IEEE.QC 20110224
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Joyce, Robert Michael. "Self-organising heterogeneous cellular networks." Thesis, University of Leeds, 2013. http://etheses.whiterose.ac.uk/6521/.
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The mobile communications market has experienced massive growth over the past 10 years, fuelled by the continuing take up of mobile services in the developing world and the exponential mobile data growth seen in the developed world. Current forecasts predict that today’s global mobile data traffic is set to rise by over 1000% by the year 2017 and in order to cope with this demand current 2nd and 3rd generation mobile networks are now evolving toward self-organising 4th generation heterogeneous networks in most markets. To address these capacity challenges this thesis firstly explores novel means to maximise the capacity of the existing macrocell network, therefore delaying the deployment of small cells and their associated costs. To do this it considers both higher order sectorisation and self-organising dynamic antenna tilt at the macrocell and shows through both detailed simulation and field trials that both techniques provide a reasonable capacity gain and therefore delay the need for the deployment of small cells. However, given current traffic forecasts, it is accepted that small cells will be required in the future and this thesis also considers the use of Self-Organising Network techniques to ensure that these small cells are located as close as possible to traffic hotspots to maximise their traffic and cost effectiveness. The thesis then goes on to show the effectiveness of low powered small cells to offload traffic from a co-channel macrocell layer and finally proposes a number of Self-Organising Network methods to maximise traffic offload from the macrocell layer onto a deployed small cell layer.
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Dandachi, Ghina. "Multihoming in heterogeneous wireless networks." Thesis, Evry, Institut national des télécommunications, 2017. http://www.theses.fr/2017TELE0014/document.
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Les réseaux mobiles de la cinquième génération (5G) sont conçus pour introduire de nouveaux services nécessitant des débits de données extrêmement hauts et une faible latence. 5G sera un changement de paradigme qui comprend des réseaux hétérogènes densifiés, des réseaux d'accès radio virtualisés, des fréquences porteuses à ondes millimétrées et des densités de périphériques très élevées. Cependant, contrairement aux générations précédentes, 5G sera un réseau holistique, intégrant n'importe quelle nouvelle technologie radio avec les technologies LTE et WiFi existant. Dans ce contexte, on se concentre sur de nouvelles stratégies d'allocation de ressources capables de bénéficier du multihoming dans le cas d'accès double au réseau. On modélise ces algorithmes au niveau du flux et analyse leurs performances en termes de débit, de stabilité du système et d'équité entre différentes catégories d'utilisateurs. On se concentre tout d'abord sur le multihoming dans les réseaux hétérogènes LTE/WiFi. On considère les allocations centrées sur le réseau où un planificateur central effectue des allocations d'équité proportionnelle (PF) locale et globale pour différentes classes d'utilisateurs, utilisateurs individuels (single-homed) et multi-domiciliés (multihomed). Par rapport à un modèle de référence sans multihoming, on montre que les deux stratégies améliorent la performance et la stabilité du système, au détriment d'une plus grande complexité pour la stratégie PF globale. On étudie également les stratégies d'allocation centrées sur l'utilisateur, dans lesquelles les utilisateurs multihomed décident la partition de la demande d'un fichier en utilisant soit la maximisation du débit crête, soit la stratégie assistée par réseau. On montre que cette dernière stratégie maximise le débit moyen dans l'ensemble du réseau. On montre également que les stratégies centrées sur le réseau permettent d'obtenir des débits de données plus élevés que ceux centrés sur l'utilisateur. Ensuite, on se concentre sur les réseaux d'accès radio virtuels (V-RAN) et en particulier sur l'allocation de multi-ressources. On étudie la faisabilité de la virtualisation sans diminuer ni la performance des utilisateurs, ni la stabilité du système. On considère un réseau hétérogène 5G composé de cellules LTE et mm-wave afin d'étudier comment les réseaux hauts fréquence peuvent augmenter la capacité du système. On montre que la virtualisation du réseau est réalisable sans perte de performance lors de l'utilisation de la stratégie « dominant resource fairness » (DRF). On propose une stratégie d'allocation en deux phases (TPA) qui montre un indice d'équité plus élevé que DRF et une stabilité du système plus élevée que PF. On montre également des gains importants apportés par l'adoption des fréquences mm-wave au lieu de WiFi. Finalement, on considère l'efficacité énergétique et compare les stratégies DRF et TPA avec une stratégie éconergétique basée sur l'algorithme de Dinklebach. Les résultats montrent que la stratégie éconergétique dépasse légèrement DRF et TPA à charge faible ou moyenne en termes de débit moyen plus élevé avec une consommation d'énergie comparable, alors qu'elle les surpasse à une charge élevée en termes de consommation d'énergie moins élevée. Dans ce cas de charge élevée, DRF surpasse TPA et la stratégie éconergétique en termes de débit moyen. En ce qui concerne l'indice d'équité de Jain, TPA réalise l'indice d'équité le plus élevé parmi d'autres stratégiesFifth generation mobile networks (5G) are being designed to introduce new services that require extreme broadband data rates and utlra-reliable latency. 5G will be a paradigm shift that includes heterogeneous networks with densification, virtualized radio access networks, mm-wave carrier frequencies, and very high device densities. However, unlike the previous generations, it will be a holistic network, tying any new 5G air interface and spectrum with the currently existing LTE and WiFi. In this context, we focus on new resource allocation strategies that are able to take advantage of multihoming in dual access settings. We model such algorithms at the flow level and analyze their performance in terms of flow throughput, system stability and fairness between different classes of users. We first focus on multihoming in LTE/WiFi heterogeneous networks. We consider network centric allocations where a central scheduler performs local and global proportional fairness (PF) allocations for different classes of users, single-homed and multihomed users. By comparison with a reference model without multihoming, we show that both strategies improve system performance and stability, at the expense of more complexity for the global PF. We also investigate user centric allocation strategies where multihomed users decide the split of a file using either peak rate maximization or network assisted strategy. We show that the latter strategy maximizes the average throughput in the whole network. We also show that network centric strategies achieve higher data rates than the user centric ones. Then, we focus on Virtual Radio Access Networks (V-RAN) and particularly on multi-resource allocation therein. We investigate the feasibility of virtualization without decreasing neither users performance, nor system's stability. We consider a 5G heterogeneous network composed of LTE and mm-wave cells in order to study how high frequency networks can increase system's capacity. We show that network virtualization is feasible without performance loss when using the dominant resource fairness strategy (DRF). We propose a two-phase allocation (TPA) strategy which achieves a higher fairness index than DRF and a higher system stability than PF. We also show significant gains brought by mm-wave instead of WiFi. Eventually, we consider energy efficiency and compare DRF and TPA strategies with a Dinklebach based energy efficient strategy. Our results show that the energy efficient strategy slightly outperforms DRF and TPA at low to medium load in terms of higher average throughput with comparable power consumption, while it outperforms them at high load in terms of power consumption. In this case of high load, DRF outperforms TPA and the energy efficient strategy in terms of average throughput. As for Jain's fairness index, TPA achieves the highest one
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Liu, Xiaoshan, and 劉曉杉. "Mobility and radio resource management in heterogeneous wireless networks." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B38233873.
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Sundaresan, Karthikeyan. "Network Protocols for Ad-Hoc Networks with Smart Antennas." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14122.
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Multi-hop wireless networks or ad-hoc networks
face several limiting characteristics that make it difficult to support a multitude of applications. It is in this context that we find smart antennas to find significant applications in these networks, owing to their ability to alleviate most
of these limitations. The focus of my research is thus to investigate the use of smart antennas in ad-hoc networks and hence efficiently design network protocols that best leverage their capabilities in communication. There are two parts to the proposed objective of designing efficient network protocols that pertain to the nature of the smart antenna network considered, namely, homogeneous and heterogeneous smart antenna networks.
Unlike heterogeneous smart antenna networks, where different devices in the network employ different antenna technologies, homogeneous smart antenna networks consist of devices employing the same antenna technology. Further, in homogeneous smart antenna networks, different antenna technologies operating in different strategies tend to perform the best in different network architectures, conditions and application requirements. This
motivates the need for developing a {em unified} framework for designing efficient communication (medium access control and routing) protocols for homogeneous smart antenna networks in general. With the objective of designing such a unified framework, we start by designing efficient MAC and routing protocols for the most sophisticated of the smart antenna technologies, namely multiple-input multiple-output (MIMO) links. The capabilities of MIMO links form a super-set of those possible with other antenna technologies. Hence, the insights gained from the design of
communication protocols for MIMO links are then used to develop unified MAC and routing frameworks for smart antennas in general.
For heterogeneous smart antenna networks, we develop theoretical performance bounds by studying the impact of increasing degree of heterogeneity on network throughput performance. Given that the
antenna technologies are already unified in the network, unified solutions are not required. However, we do develop efficient MAC and routing protocols to best leverage the available heterogeneous capabilities present in the network. We also design efficient cooperation strategies that will further help the communication protocols in exploiting the available heterogeneous capabilities in the network to the best possible extent.
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Coutinho, Nuno Alexandre Tavares. "Seamless integration of heterogeneous networks in multicast environments." Doctoral thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/14193.
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Doutoramento em Engenharia ElectrotécnicaNowadays, communication environments are already characterized by a myriad of competing and complementary technologies that aim to provide an ubiquitous connectivity service. Next Generation Networks need to hide this heterogeneity by providing a new abstraction level, while simultaneously be aware of the underlying technologies to deliver richer service experiences to the end-user. Moreover, the increasing interest for group-based multimedia services followed by their ever growing resource demands and network dynamics, has been boosting the research towards more scalable and exible network control approaches. The work developed in this Thesis enables such abstraction and exploits the prevailing heterogeneity in favor of a context-aware network management and adaptation. In this scope, we introduce a novel hierarchical control framework with self-management capabilities that enables the concept of Abstract Multiparty Trees (AMTs) to ease the control of multiparty content distribution throughout heterogeneous networks. A thorough evaluation of the proposed multiparty transport control framework was performed in the scope of this Thesis, assessing its bene ts in terms of network selection, delivery tree recon guration and resource savings. Moreover, we developed an analytical study to highlight the scalability of the AMT concept as well as its exibility in large scale networks and group sizes. To prove the feasibility and easy deployment characteristic of the proposed control framework, we implemented a proof-of-concept demonstrator that comprehends the main control procedures conceptually introduced. Its outcomes highlight a good performance of the multiparty content distribution tree control, including its local and global recon guration. In order to endow the AMT concept with the ability to guarantee the best service experience by the end-user, we integrate in the control framework two additional QoE enhancement approaches. The rst employs the concept of Network Coding to improve the robustness of the multiparty content delivery, aiming at mitigating the impact of possible packet losses in the end-user service perception. The second approach relies on a machine learning scheme to autonomously determine at each node the expected QoE towards a certain destination. This knowledge is then used by di erent QoE-aware network management schemes that, jointly, maximize the overall users' QoE. The performance and scalability of the control procedures developed, aided by the context and QoE-aware mechanisms, show the advantages of the AMT concept and the proposed hierarchical control strategy for the multiparty content distribution with enhanced service experience. Moreover we also prove the feasibility of the solution in a practical environment, and provide future research directions that bene t the evolved control framework and make it commercially feasible.
Atualmente, os ambientes de comunicação caracterizam-se pela diversidade de tecnologias concorrentes e complementares cujo principal objetivo é fornecer conectividade de forma ubíqua. De forma a lidar com esta heterogeneidade, as redes de próxima geração terão de suportar um novo nível de abstração, embora simultaneamente necessitem de estar conscientes das tecnologias presentes de forma a oferecer uma melhor experiência do serviço ao utilizador final. Para além disso, o crescente interesse por comunicações multimédia para grupos de utilizadores e as cada vez maiores exigências em termos de recursos e dinâmica da rede destes serviços, tem motivado a investigação no sentido de desenvolver soluções de controlo da rede mais escaláveis e flexíveis. O trabalho desenvolvido nesta Tese, não só aborda o suporte da camada de abstração, como também explora a heterogeneidade presente em prol de uma gestão e adaptação da rede consciente do seu contexto. Neste âmbito, é introduzida nesta Tese uma nova estrutura hierárquica de controlo com capacidades de auto-gestão que possibilitam o conceito de Abstract Multiparty Trees (AMTs) de forma a facilitar o controlo da distribuição de conteúdos para grupos através de redes heterogéneas. Nesta Tese foi também realizada uma avaliação detalhada da estrutura de controlo de forma a aferir os benefícios do controlo da rede baseado na informação de contexto, no que diz respeito à seleção da rede, reconfiguração da árvore de distribuição, poupança de recursos e operações de gestão. Para além disso, foi também desenvolvido um estudo analítico para destacar a escalabilidade do conceito AMT, bem como da sua flexibilidade perante redes de grande escala e um vasto número de potenciais utilizadores. De forma a provar a viabilidade e fácil aplicação da estrutura de controlo proposta, foi implementado um demonstrador para prova de conceito que inclui os principais procedimentos de controlo introduzidos conceptualmente. Os resultados da avaliação do demonstrador salientam o bom desempenho no controlo da árvore de distribuição de conteúdos, bem como nos processos de reconfiguração local e global da mesma. Com o intuito de dotar o conceito AMT com a capacidade de garantir a melhor experiência de serviço pelo utilizador final, integrou-se na estrutura de controlo proposta dois mecanismos para melhorar a Qualidade de Experiência (QoE). O primeiro baseia-se na utilização do conceito de Codificação de Rede para melhorar a robustez da entrega de conteúdos a grupos, tendo como objetivo eliminar o impacto da possível perda de pacotes na perceção do serviço por parte do utilizador. O segundo mecanismo tira partido do conceito de aprendizagem automática para que, de forma autónoma, seja capaz de determinar em cada nó da rede o valor expectável de QoE para um dado destino. Este conhecimento é depois utilizado por diferentes mecanismos de gestão de rede sensíveis a QoE para de forma conjunta maximizar a percepção do serviço por parte dos utilizadores finais. O desempenho e a escalabilidade dos processos de controlo desenvolvidos, com a ajuda dos mecanismos sensíveis ao contexto e à QoE, demonstram as vantagens do conceito AMT e da estrutura de controlo hierárquica para a distribuição de conteúdos a grupos com uma experiência de serviço melhorada. Para além disso, é também demonstrada a praticabilidade da nossa solução, bem como possíveis linhas de investigação que podem melhorar a estrutura de controlo proposta e fazer dela comercialmente aplicável.
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Basarudin, Hafiz. "Development of a heterogeneous microwave network, fade simulation tool applicable to networks that span Europe." Thesis, University of Hull, 2012. http://hydra.hull.ac.uk/resources/hull:5774.
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Radio communication systems operating at microwave frequencies are strongly attenuated by hydrometeors such as rain and wet snow (sleet). Hydrometeor attenuation dominates the dynamic fading of most types of radio links operating above 10 GHz, especially high capacity, fixed, terrestrial and Earth-Space links. The International Telecommunication Unions – Radio Section (ITU-R) provides a set of internationally recognized models to predict annual fade distributions for a wide variety of individual radio link. However, these models are not sufficient for the design and optimisation of networks, even as simple as two links. There are considerable potential gains to be achieved from the optimized design of real-time or predictive Dynamic Resource Management systems. The development of these systems requires a joint channel simulation tool applicable to arbitrary, heterogeneous networks. This thesis describes the development of a network fade simulation tool, known as GINSIM, which can simulate joint dynamic fade time-series on heterogeneous networks of arbitrary geometry, spanning Europe. GINSIM uses as input meteorological and topological data from a variety of sources and numerically calculates the joint effects on fading on all links in a specified network. ITU-R models are used to transform rain rate into specific attenuation and to estimate the specific attenuation amplification due to non-liquid hydrometeors. The resulting simulation tool has been verified against ITU-R models of average annual fade distributions, fade slope and fade duration distributions, in the southern UK. Validation has also been performed against measured terrestrial and Earth-space link data, acquired in the Southern UK and Scotland.
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Rehman, Faisal. "Heterogeneous Embedded Network Architecture." Thesis, Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-2529.
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In this thesis we focused on high performance embedded real-time networks which are designed for systems like radar signalling processing systems, control systems etc. These high performance embedded networks consist of emerging standards like PCI Express, RapidIO, and standard Ethernet. All of these switched embedded networks communicate with each other through common gateway nodes. As these networks have different rate characteristics, maximum packet size (MTU), packet priorities, addressing schemes etc we have therefore defined the gateway nodes for these heterogeneous embedded networks which will allow these heterogeneous embedded networks to communicate with each other with the help of different translation functions. These gateway nodes allow end-to-end transmission across the heterogeneous embedded networks while keeping bound on end-to-end delay and guaranteed throughput. We need to have some flow control mechanism which will shape the traffic flow in the mentioned embedded networks and will avoid from buffer overflow.
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Sharma, Sachin. "Integrated Backhaul Management for Ultra-Dense Network Deployment." Thesis, KTH, Kommunikationssystem, CoS, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-159447.
Full textAbstract:
Mobile data traffic is expected to increase substantially in the coming years, with data rates 1000 times higher by 2020, having media and content as the main drivers together with a plethora of new end-user services that will challenge existing networks. Concepts and visions associated with the ICT evolution like the network society, 50 billion connected devices, Industrial Internet, Tactile Internet, etc., exemplifies the range of new services that the networks will have to handle. These new services impose extreme requirement to the network like high capacity, low latency, reliability, security, seamless connectivity, etc. In order to face these challenges, the whole end-to-end network has to evolve and adapt, pushing for advances in different areas, such as transport, cloud, core, and radio access networks. This work investigates the impact of envisioned 2020 society scenarios on transport links for mobile backhaul, emphasizing the need for an integrated and flexible/adaptive network as the way to meet the 2020 networks demands. The evolution of heterogeneous networks and ultra-dense network deployments shall also comprise the introduction of adaptive network features, such as dynamic network resource allocation, automatic integration of access nodes, etc. In order to achieve such self-management features in mobile networks, new mechanisms have to be investigated for an integrated backhaul management. First, this thesis performs a feasibility study on the mobile backhaul dimensioning for 2020 5G wireless ultra-dense networks scenarios, aiming to analyze the gap in capacity demand between 4G and 5G networks. Secondly, the concept of an integrated backhaul management is analyzed as a combination of node attachment procedures, in the context of moving networks. In addition, the dynamic network resource allocation concept, based on DWDM-centric transport architecture, was explored for 5G scenarios assuming traffic variation both in time and between different geographical areas. Finally, a short view on techno-economics and network deployments in the 2020 time frame is provided.
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Martorello, Cristiane Dias de Souza. "Epidemiology in complex networks - modified heterogeneous mean-field model." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/100/100132/tde-16012019-173906/.
Full textAbstract:
The study of complex networks presented a huge development in last decades. In this dissertation we want to analyze the epidemic spread in scale-free networks through the Susceptible - Infected - Susceptible (SIS) model. We review the fundamental concepts to describe complex networks and the classical epidemiological models. We implement an algorithm that produces a scale-free network and explore the Quenched Mean-Field (QMF) dynamics in a scale-free network. Moreover, we simulate a change on the topology of the network according to the states of the nodes, and it generates a positive epidemic threshold. We show analytically that the fraction of infected vertices follows a power-law distribution in the vicinity of this critical pointO estudo de redes complexas tem se desenvolvido muito nos últimos anos. Nesta dissertação queremos analisar o processo de propagação de epidemia em redes livres de escala através do modelo Suscetível - Infectado - Suscetível (SIS). Apresentamos uma revisão de redes e as principais características dos modelos epidemiológicos clássicos. Implementamos um algoritmo que produz uma rede livre de escala dado um expoente e exploramos a dinâmica do modelo Quenched Mean-Field (QMF) inserido em uma rede livre de escala. Além disso, foi simulada uma possível alteração na topologia da rede, devido aos estados dos vértices infectados, que gerou um limiar epidêmico positivo no modelo e a probabilidade de vértices infectados seguiu uma lei de potência na vizinhança desse ponto crítico
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Hsieh, Hung-Yun. "Addressing Network Heterogeneity and Bandwidth Scarcity in Future Wireless Data Networks." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5063.
Full textAbstract:
To provide mobile hosts with seamless and broadband wireless Internet access, two fundamental problems that need to be tackled in wireless networking are transparently supporting host mobility and effectively utilizing wireless bandwidth. The increasing heterogeneity of wireless networks and the proliferation of wireless devices, however, severely expose the limitations of the paradigms adopted by existing solutions. In this work, we explore new research directions for addressing network heterogeneity and bandwidth scarcity in future wireless data networks. In addressing network heterogeneity, we motivate a transport layer solution for transparent mobility support across heterogeneous wireless networks. We establish parallelism and transpositionality as two fundamental principles to be incorporated in designing such a transport layer solution. In addressing bandwidth scarcity, we motivate a cooperative wireless network model for scalable bandwidth utilization with wireless user population. We establish base station assistance and multi-homed peer relay as two fundamental principles to be incorporated in designing such a cooperative wireless network model. We present instantiations based on the established principles respectively, and demonstrate their performance and functionality gains through theoretic analysis, packet simulation, and testbed emulation.