Dissertations / Theses on the topic 'Resource sharing'

Thesis (M.A. in Security Studies (Homeland Security and Defense))--Naval Postgraduate School, September 2005.
Thesis Advisor(s): Christopher Bellavita. Includes bibliographical references (p. 35-37). Also available online.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2006.
Includes bibliographical references (p. 121-124).
This thesis presents an Internet resource sharing architecture. It allows users to access and utilize unused computer resources, such as CPU cycles and storage, without an expert's knowledge. It achieves this by providing a number of abstract services that hide some of the complexity inherent in distributed computing. In recent years, Grid Computing has been proposed as a solution for Internet resource sharing. However, Grid Computing as presently implemented does not address the need of the large majority of the users. In this thesis, we propose a different approach to achieve Internet resource sharing called the Realm. The Realm Framework offers a lightweight layer on top of the Microsoft .Net Framework so that the programs that can be migrated to .Net Framework can also utilize the shared resources through the Realm Framework. By leveraging the Microsoft .Net Framework, the Realm Framework avoids tedious re-working in this fast-paced world of technology by sitting on the top of the full-featured, coherent and up-to-date development platform. The Realm Framework applies current technologies such as Web Services, the Common Language Runtime (CLR) and popular encryption algorithms.
(cont.) In this thesis a versatile runtime system and a set of extension interfaces in C# programming language is developed. The modularized software package offers a layered programming model for distributed-application developers with different levels of proficiency. Two utilities that are helpful for maintaining a distributed system are also developed, namely, a dynamic domain-name based inter-realm communication scheme and a distributed debugger. Examples of applying the Realm Framework to several typical scenarios are shown, including embarrassingly parallel problems that require little communication between computing nodes, parallel computing problems that require intensive message-passing between the computing nodes, and universal storage systems that are based on storage media and the messenger-like applications that require a sophisticated communication scheme.
by Xiaohan Lin
Ph.D.

L'objectif principal de cette thèse est de proposer une approche efficace de modélisation et de résolution pour le problème d’ordonnancement, en mettant l’accent sur le partage multi-ressources et sur l’incertitude potentielle d’occurrence de certains événements. L'ordonnancement a pour objectif de réaliser un ensemble de tâches à la fois en respectant des contraintes prédéfinies et en optimisant le temps. Ce travail s’intéresse en particulier à la minimisation du temps total d’exécution. La plupart des approches existantes préconisent une modélisation mathématique exprimant des équations et des contraintes pour décrire et résoudre des problèmes d’ordonnancement. De telles démarches ont une complexité inhérente. Cependant dans l’industrie, la tâche de planification est récurrente et peut requérir des changements fréquents des contraintes. Outre cela, la prise en compte d’événements incertains est peu supportée par les approches existantes; cela peut toutefois augmenter la robustesse d’un ordonnancement. Pour répondre à ces problématiques, après une introduction, le chapitre 2 aborde le problème de l’ordonnancement à travers une démarche de modélisation visuelle, expressive et formelle, s’appuyant sur les automates pondérés et sur la théorie des automates temporisés. L’originalité des modèles proposés réside aussi dans leur capacité de décrire le partage de ressources multiples et proposer une approche de résolution efficace. Ces modèles ont l’avantage d’être directement exploitables par des outils de vérification formelle, à travers une démarche de preuve par contradiction vis-à-vis de l’existence d’une solution. Les résultats effectifs sont obtenus grâce à l’outil UPPAAL. La complexité inhérente à la production d’une solution optimale est abordée à travers un algorithme de recherche et d’amélioration itérative de solutions, offrant une complexité très prometteuse sur la classe de problèmes étudiés. Dans le chapitre 3, une composition synchrone est d’automates pondérés est proposée dans le but de résoudre le problème d’ordonnancement en effectuant une analyse d’atteignabilité optimale directement sur les modèles automates pondérés. Dans le quatrième chapitre, divers comportements incontrôlables tels que le temps de début, la durée de la tâche et l'occurrence d’échec dans un problème d‘ordonnancement sont modélisés par des automates de jeu temporisés. Ensuite, le problème est résolu en effectuant une synthèse de stratégie optimale dans le temps dans l'outil de synthèse TIGA
The objective of scheduling problems is to find the optimal performing sequence for a set of tasks by respecting predefined constraints and optimizing a cost: time, energy, etc. Despite classical approaches, automata models are expressive and also robust against changes in the parameter setting and against changes in the problem specification. Besides, few studies have used formal verification approaches for addressing scheduling problems; yet none of them considered challenging and practical issues such as multi-resource sharing aspect, uncontrollable environment and reaching the optimal schedule in a reasonable time for industrializing the model. The main objective of this thesis is to propose an efficient modeling and solving approach for the scheduling problem, considering multi-resource sharing and potential uncertainty in occurrence of certain events. For this purpose, after an introduction in Chapter 1, Chapter 2 addresses the problem of scheduling through a visual, expressive and formal modeling approach, based on weighted automata and the theory of timed automata. The originality of the proposed approach lies in ability of handling the sharing of multiple resources and proposing an efficient solving approach. The proposed models have the advantage of being directly exploitable by means of formal verification tools. The results are obtained using the UPPAAL tool. To solve the problem, an algorithm is developed based on iterating reachability analysis to obtain sub-optimal makespan. Results show the proposed model and solving approach provides a very promising complexity on the class of studied problems and can be applied to industrial cases. In Chapter 3, a synchronous composition of weighted automata is proposed to solve the scheduling problem by performing an optimal reachability analysis directly on the weighted automata models. In the fourth chapter, various uncontrollable behaviors such as the start time, the duration of the task and the failure occurrence in a scheduling problem are modeled by timed game automata. Then, the problem is solved by performing an optimal strategy synthesis over time in TIGA as a synthesis tool

The project aims at solving the problem of non-repudiation, integrity and confidentiality of data when digitally exchanging sensitive resources between parties that need to be able to trust each other without the need for a trusted third party. This is done in the framework of answering to what extent digital resources can be shared securely in a decentralized public ledger-based system compared to trust-based alternatives. A background of existing resource sharing solutions is explored which shows an abundance third party trust-based systems, but also an interest in public ledger solutions in the form of the Storj network which uses such technology, but focuses on storage rather than sharing. The proposed solution, called SecuRES, is a communication protocol based on public ledger technology which acts similar to Bitcoin. A prototype based on the protocol has been implemented which proves the ability to share encrypted files with one or several recipients through a decentralized public ledger-based network. It was concluded that the SecuRES solution could do away with the requirement of trust in third parties for all but some optional operations using external authentication services. This is done while still maintaining data integrity of a similar or greater degree to trust-based solutions and offers the additional benefits of non-repudiation, high confidentiality and high transparency from the ability to make source code and protocol documentation openly available without endangering the system. Further research is needed to investigate whether the system can scale up for widespread adoption while maintaining security and reasonable performance requirements.
Projektet ämnar lösa problemen med oförnekbarhet, integritet och konfidentialitet när man delar känsligt data mellan parter som behöver lita på varandra utan inblanding av betrodd tredje part. Detta diskuteras för att besvara till vilken omfattning digitala resurser kan delas säkert i ett decentraliserat system baserat på publika liggare jämfört med existerande tillitsbaserade alternativ. En undersökning av nuvarande resursdelningslösningar visar att det existerar många tillitsbaserade system men även en växande andel lösningar baserade på publika liggare. En intressant lösning som lyfts fram är Storj som använder sådan teknologi men fokuserar på resurslagring mer är delning. Projektets föreslagna lösning, kallad SecuRES, är ett kommunikationsprotokoll baserat på en publik liggare likt Bitcoin. En prototyp baserad på protokollet har tagits fram som visar att det är möjligt att dela krypterade filer med en eller flera mottagare genom ett decentraliserat nätverk baserat på publika liggare. Slutsatsen som dras är att SecuRES klarar sig utan betrodda tredje parter för att dela resurser medan vissa operationer kan göras mer användarvänliga genom externa autentiseringstjänster. Själva lösningen garanterar integritet av data och medför ytterligare fördelar såsom oförnekbarhet, konfidentialitet och hög transparens då man kan göra källkoden och protocoldokumentation fritt läsbar utan att utsätta systemet för fara. Vidare forskning behövs för att undersöka om systemet kan skalas upp för allmän användning och alltjämt bibehålla säkerhets- samt prestandakrav.

In recent years multiprocessor architectures have become mainstream, and multi-core processors are found in products ranging from small portable cell phones to large computer servers. In parallel, research on real-time systems has mainly focused on traditional single-core processors. Hence, in order for real-time systems to fully leverage on the extra capacity offered by new multi-core processors, new design techniques, scheduling approaches, and real-time analysis methods have to be developed. In the multi-core and multiprocessor domain there are mainly two scheduling approaches, global and partitioned scheduling. Under global scheduling each task can execute on any processor at any time while under partitioned scheduling tasks are statically allocated to processors and migration of tasks among processors is not allowed. Besides simplicity and efficiency of partitioned scheduling protocols, existing scheduling and synchronization techniques developed for single-core processor platforms can more easily be extended to partitioned scheduling. This also simplifies migration of existing systems to multi-cores. An important issue related to partitioned scheduling is the distribution of tasks among the processors, which is a bin-packing problem. In this thesis we propose a blocking-aware partitioning heuristic algorithm to distribute tasks onto the processors of a multi-core architecture. The objective of the proposed algorithm is to decrease the blocking overhead of tasks, which reduces the total utilization and has the potential to reduce the number of required processors. In industrial embedded software systems, large and complex systems are usually divided into several components (applications) each of which is developed independently without knowledge of each other, and potentially in parallel. However, the applications may share mutually exclusive resources when they co-execute on a multi-core platform which introduce a challenge for the techniques needed to ensure predictability. In this thesis we have proposed a new synchronization protocol for handling mutually exclusive resources shared among real-time applications on a multi-core platform. The schedulability analysis of each application is performed in isolation and parallel and the requirements of each application with respect to the resources it may share are included in an interface. The protocol did not originally consider any priorities among the applications. We have proposed an additional version of the protocol which grants access to resources based on priorities assigned to the applications. We have also proposed an optimal priority assignment algorithm to assign unique priorities to the applications sharing resources. Our evaluations confirm that the protocol together with the priority assignment algorithm outperforms existing alternatives in most cases. In the proposed synchronization protocol each application is assumed to be allocated on one dedicated core. However, in this thesis we have further extended the synchronization protocol to be applicable for applications allocated on multiple dedicated cores of a multi-core platform. Furthermore, we have shown how to efficiently calculate the resource hold times of resources for applications. The resource hold time of a resource for an application is the maximum duration of time that the application may lock the resource whenever it requests the resource. Finally, the thesis discusses and proposes directions for future work.

Semi-partitioned scheduling has been the subject of interest compared to conventional global and partitioned scheduling algorithms for multiprocessors due to better utilization results. In Semi-partitioned scheduling most of tasks are assigned to fixed processors while a few number of tasks are split up and allocated to different processors. Various techniques have been proposed recently on different assigning protocols under semi-partitioned scheduling. Yet an appropriate synchronization mechanism for resource sharing in semi-partitioned scheduling have not been investigated. In this thesis we propose two methods for handling resource sharing under semi-partitioned scheduling on multiprocessor platforms. The main challenge is handling the resource requests of tasks that are split over multiple processors. The solutions include handling non-split tasks as well as split tasks over requests for shared resources in the system. In this thesis we investigate delays caused by blocking on resources. Furthermore, we perform the schedulability analysis for both algorithms. Finally we evaluate the performance of our proposed synchronization algorithms by means of experimental evaluations.

Spectrum access protocols have been proposed recently to provide flexible and efficient use of the available bandwidth. Game theory has been applied to the analysis of the problem to determine the most effective allocation of the users’ power over the bandwidth. However, prior analysis has focussed on Shannon capacity as the utility function, even though it is known that real signals do not, in general, meet the Gaussian distribution assumptions of that metric. In a non-cooperative spectrum sharing environment, the Shannon capacity utility function results in a water-filling solution. In this thesis, the suitability of the water-filling solution is evaluated when using non-Gaussian signalling first in a frequency non-selective environment to focus on the resource allocation problem and its outcomes. It is then extended to a frequency selective environment to examine the proposed algorithm in a more realistic wireless environment. It is shown in both scenarios that more effective resource allocation can be achieved when the utility function takes into account the actual signal characteristics. Further, it is demonstrated that higher rates can be achieved with lower transmitted power, resulting in a smaller spectral footprint, which allows more efficient use of the spectrum overall. Finally, future spectrum management is discussed where the waveform adaptation is examined as an additional option to the well-known spectrum agility, rate and transmit power adaptation when performing spectrum sharing.

Embedded systems are widely used in the industry and are typically resource constrained, i.e., resources such as processors, I/O devices, shared buffers or shared memory might be limited in the system. Hence, techniques that can enable an efficient usage of processor bandwidths in such systems are of great importance. Locked-based resource sharing protocols are proposed as a solution to overcome resource limitation by allowing the available resources in the system to be safely shared. In recent years, due to a dramatic enhancement in the functionality of systems, a shift from single-core processors to multi-core processors has become inevitable from an industrial perspective to tackle the raised challenges due to increased system complexity. However, the resource sharing protocols are not fully mature for multi-core processors. The two classical multi-core processor resource sharing protocols, spin-based and suspension-based protocols, although providing mutually exclusive access to resources, can introduce long blocking delays to tasks, which may be unacceptable for many industrial applications. In this thesis we enhance the performance of resource sharing protocols for partitioned scheduling, which is the de-facto scheduling standard for industrial real-time multi-core processor systems such as in AUTOSAR, in terms of timing and memory requirements.   A new scheduling approach uses a resource efficient hybrid approach combining both partitioned and global scheduling where the partitioned scheduling is used to schedule the major number of tasks in the system. In such a scheduling approach applications with critical task sets use partitioned scheduling to achieve higher level of predictability. Then the unused bandwidth on each core that is remained from partitioning is used to schedule less critical task sets using global scheduling to achieve higher system utilization. These scheduling schema however lacks a proper resource sharing protocol since the existing protocols designed for partitioned and global scheduling cannot be directly applied due to the complex hybrid structure of these scheduling frameworks. In this thesis we propose a resource sharing solution for such a complex structure. Further, we provide the blocking bounds incurred to tasks under the proposed protocols and enhance the schedulability analysis, which is an essential requirement for real-time systems, with the provided blocking bounds.

Resource sharing is a common collaborative strategy used in practice. It has the potential to create synergistic value and leads to higher system efficiency. However, realizing this synergistic value can be challenging given the prevalence of decentralization in practice, where individual operators manage resources based on their own benefits. Hence, optimizing a decentralized system requires understanding not only the optimal operational strategy in terms of the overall system efficiency, but also the implementation of the strategy through proper management of individual incentives. However, traditional network optimization approaches typically assume a centralized perspective. The classic game theory framework, on the other hand, addresses incentive issues of decentralized decision makers, but mainly takes a high-level, economic perspective that does not fully capture the operational complexity involved in optimizing systems with resource sharing. The purpose of this thesis is to bridge this gap between practice and theory by studying the design of tools to manage and optimize the operations in decentralized systems with resource sharing using approaches that combine optimization and game theory. In particular, we focus on decentralized network systems and analyze two research streams in two application domains: (i) implementation of environmental legislation, and (ii) managing collaborative transportation systems. These applications are characterized by their decentralized multi-stakeholder nature where the conflicts and tension between the heterogeneous individual perspectives make system management very challenging. The main methodology used in this thesis is to adopt game theory models where individual decisions are endogenized as the solutions to network optimization problems that reflect their incentives. Such an approach allows us to capture the connection between the operational features of the system (e.g., capacity configuration, network structure, synergy level from resource sharing) and the individual incentives thus the effectiveness of the management tools, which is a main research contribution of this thesis. In the first research stream, we consider designing effective, efficient and practical implementation of electronic waste take-back legislation based on the widely-adopted Extended Producer Responsibility (EPR) concept that mandates the financial responsibility of post-use treatment of their products. Typical implementations of EPR are collective, and allocate the resulting operating cost to involved producers. In this thesis, we demonstrate the complexity of collective EPR implementation due to the tension among different stakeholder perspectives, based on a case analysis of the Washington implementation. We then perform analytical studies of the two prominent challenges identified in current implementations: (i) developing cost allocation mechanisms that induce the voluntary participation of all producers in a collective system, thus promoting implementation efficiency; and (ii) designing collective EPR so as to encourage environmentally-friendly product design, thus promoting implementation effectiveness. Specifically, we prescribe new cost allocation methods to address the first challenge, and demonstrate the practicality and economic impact of the results using implementation data from the state of Washington. We then analyze the tensions between design incentives, efficiency and the effectiveness of the cost allocation to induce voluntary participation under collective EPR implementation. We show there exists a tradeoff among the three dimensions, driven by the network effects inherent in a collective system. The main contribution of this research stream is to demonstrate how the implementation outcomes of an environmental policy is influenced by the way that the policy ``filters' through operational-level factors, and to propose novel and implementation mechanisms to achieve efficient and effective EPR implementation. Hence, our study has the potential to provide guidance for practice and influence policy-making. In the second research stream, motivated by the practice of transportation alliances, we focus on a decentralized network setting where the individual entities make independent decisions regarding the routing of their own demand and the management of their own capacity, driven by their own benefits. We study the use of market-based exchange mechanisms to motivate and regulate capacity sharing so as to achieve the optimal overall routing efficiency in a general multicommodity network. We focus on the design of capacity pricing strategies in the presence of several practical operational complexities, including multiple ownership of the same capacity, uncertainty in network specifications, and information asymmetry between the central coordinator and individual operators. Our study in this research stream produces two sets of results. First, we demonstrate the impact of the underlying network structure on the effectiveness of using market-based exchange mechanisms to coordinate resource sharing and to allocate the resulting synergistic benefit, and characterize the network properties that matter. Second, we propose efficient and effective pricing policies and other mechanism design strategies to address different operational complexities. Specifically, we develop duality-based pricing algorithms, and evaluate different pricing strategies such as commodity-based price discrimination, which is shown to have an advantage in coordinating networks under uncertainty.

In wireless networks, some of the most important supporting functionalities are decentralized resource sharing and association of clients to access points. These functionalities aim to optimally allocate the available wireless transmission resources, for example, time or spectrum channels, the transmit power, access points, and relaying opportunities, all of which are subject to availability constraints. Decentralized resource sharing and association are designed by a common background theory: optimization problems that are non-convex with mixed integer-real variables, and need to be solved by distributed algorithms over the network nodes. The thesis investigates these optimization problems and establishes novel solution methods based on auction and Lagrangian duality theories. The thesis is divided into two parts: in the first part, the theoretical background of the thesis is given, and novel results on distributed auction theory are established to solve a class of optimization problems with integer variables. These theoretical background and novel results are then used in the second part of the thesis, where published or submitted papers are reported. Specifically, novel solution methods for distributed optimization problems with mixed integer-real variables are in- vestigated for resource sharing and association problems in cognitive radio networks, and in millimeter wave networks. In the first paper (J1), a non-convex optimization problem with mixed integer and real variables is considered for resource allocation in a cognitive radio network. In this network, unlicensed secondary users can maximize their achievable transmit rates by cooperating with licensed primary users. An optimization problem to maximize the secondary users achievable rates is proposed by controlling the transmit radio power, the secondary users relaying selection, and power splitting of the relays, while guaranteeing primary users performance. A novel distributed solution method is developed to find the solution to such a challenging mixed integer and non-convex problem. The method provides a distributed algorithm for finding the optimal power allocations for secondary users, and a greedy distributed algorithm for finding the associations between primary and secondary users. Optimality and convergence of the solution method are investigated. The numerical results illustrate the performance of the proposed solution methods, and show that they give a near-to-optimal solution. In the second paper, the solution methods investigated in the first paper are used for mixed integer-real optimization problems in millimeter wave networks. These networks are emerging to enable extremely high data rates wireless communications. The main limiting factors of millimeter wave networks are communication blockage (due to high penetration loss of the transmit signals) and deafness (misalignment between the antenna’s beams of the transmitter and receiver). To minimize these limiting factors, it is imperative to design efficient association between clients and access points. Therefore, a general optimization framework to maximize network throughput considering both blockage and deafness is proposed. The optimization framework considers static networks (i.e., no client mobility) and investigates a novel distributed auction based solution, where the clients and access points act asynchronously to achieve optimal association along with the optimal beamwidth of the antennas. A convergence proof and optimality of the auction algorithm are analyzed. The optimization framework investigated in the second paper was intended for static networks. In networks with dynamic topologies and channel variations, the dynamic appearance of obstacles or of small misalignments between antenna beams of the transmitters and receivers may trigger the reexecution of the association mechanism, which is time consuming and may be inefficient. This challenge is addressed in the third paper by dynamic distributed association techniques that are robust to wireless channel variations and client mobility. The association problem is formulated as a mixed-integer optimization problem aiming to maximize the network throughput with proportional fairness guarantees. This optimization problem is solved by a distributed dual decomposition algorithm, and by a novel dynamic distributed auction algorithm. A distinguishing novel feature of the proposed algorithms is that the resulting optimal association does not have to be re-computed every time the network changes (e.g., due to client mobility). Instead, it is proved that the algorithm continuously adapts to the network variation and is thus capable to continuously track the optimal solutions. It is shown that the proposed algorithm provably converges to a solution that maximizes the aggregate network utility within a desired bound. The previous line of research is then extended to the case where, in addition to designing the association clients-access points, also relays nodes are considered. The association of clients to relaying nodes can provide more uniform quality of service by offering robust millimeter waves connection, load balancing, coverage extension, indoor-outdoor coverage, efficient mobility management, and smooth handover operations. The challenges of clientrelay-access point association are addressed in a sequence of two contributions having different optimization goals: the first one considers the throughput maximization, and the second one the load balancing. In the first contribution (presented in the fourth paper of the thesis), a distributed optimization that solves the joint client association and relaying problem is investigated for the throughput maximization. The optimization problem is posed as a novel multi-dimension assignment optimization, for which an original solution method is established by a series of transformations together with a distributed auction solution algorithm. In the second contribution (presented in the fifth paper of the thesis), the joint association and relaying problem is posed as a novel stochastic optimization problem considering the load balancing, and the resource sharing at access points. The problem is solved by a distributed auction algorithm where the clients and relays act asyn- chronously to quickly achieve optimal association. The convergence time and performance bounds of the algorithm are derived in closed-forms. Numerical results quantify the performance enhancements introduced by the relays, and the substantial improvements of the network throughput and fairness among the clients by the proposed association methods compared to existing approaches. The common thread in the line of research reported in the papers of the thesis is given by the solution methods of mixed integer optimization problems that must be solved in a distributed manner. The core result of the thesis is a novel distributed approach, based on the auction theory, for the computation of the solution of a class of optimization problems. It is shown that such an approach can work in static and dynamic network topologies and exhibits convergence and optimality guarantees by leveraging the specific assumptions of the problems’ constraints. Future study could extend the proposed distributed auction method for more general optimization problems for association, such as generalized assignment problems.

QC 20160125

As the wireless communication technologies evolve and the demand of wireless services increases, spectrum scarcity becomes a bottleneck that limits the introduction of new technologies and services. Spectrum sharing between primary and secondary users has been brought up to improve spectrum efficiency. In underlay spectrum sharing, the secondary user transmits simultaneously with the primary user, under the constraint that the interference induced at the primary receiver is below a certain threshold, or a certain primary rate requirement has to be satisfied. Specifically, in this thesis, the coexistence of a multiple-input single-output (MISO) primary link and a MISO/multiple-input multiple-output (MIMO) secondary link is studied. The primary transmitter employs maximum ratio transmission (MRT), and single-user decoding is deployed at the primary receiver. Three scenarios are investigated, in terms of the interference from the primary transmitter to the secondary receiver, namely, weak interference, strong interference and very strong interference, or equivalently three ranges of primary rate requirement. Rate splitting and successive decoding are deployed at the secondary transmitter and receiver, respectively, when it is feasible, and otherwise single-user decoding is deployed at the secondary receiver. For each scenario, optimal beamforming/precoding and power allocation at the secondary transmitter is derived, to maximize the achievable secondary rate while satisfying the primary rate requirement and the secondary power constraint. Numerical results show that rate splitting at the secondary transmitter and successive decoding at the secondary receiver does significantly increase the achievable secondary rate if feasible, compared with single-user decoding at the secondary receiver. In overlay spectrum sharing, different from underlay spectrum sharing, the secondary transmitter can utilize the knowledge of the primary message, which is acquired non-causally (i.e., known in advance before transmission) or causally (i.e., acquired in the first phase of a two-phase transmission), to help transmit the primary message besides its own message. Specifically, the coexistence of a MISO primary link and a MISO/MIMO secondary link is studied. When the secondary transmitter has non-causal knowledge of the primary message, dirty-paper coding (DPC) can be deployed at the secondary transmitter to precancel the interference (when decoding the secondary message at the secondary receiver), due to the transmission of the primary message from both transmitters. Alternatively, due to the high implementation complexity of DPC, linear precoding can be deployed at the secondary transmitter. In both cases, the primary transmitter employs MRT, and single-user decoding is deployed at the primary receiver; optimal beamforming/precoding and power allocation at the secondary transmitter is obtained, to maximize the achievable secondary rate while satisfying the primary rate requirement and the secondary power constraint. Numerical results show that with non-causal knowledge of the primary message and the deployment of DPC at the secondary transmitter, overlay spectrum sharing can achieve a significantly higher secondary rate than underlay spectrum sharing, while rate loss occurs with the deployment of linear precoding instead of DPC at the secondary transmitter. When the secondary transmitter does not have non-causal knowledge of the primary message, and still wants to help with the primary transmission in return for the access to the spectrum, it can relay the primary message in an amplify-and-forward (AF) or a decode-and-forward (DF) way in a two-phase transmission, while transmitting its own message. The primary link adapts its transmission strategy and cooperates with the secondary link to fulfill its rate requirement. To maximize the achievable secondary rate while satisfying the primary rate requirement and the primary and secondary power constraints, in the case of AF cooperative spectrum sharing, optimal relaying matrix and beamforming vector at the secondary transmitter is obtained; in the case of DF cooperative spectrum sharing, a set of parameters are optimized, including time duration of the two phases, primary transmission strategies in the two phases and secondary transmission strategy in the second phase. Numerical results show that with the cooperation from the secondary link, the primary link can avoid outage effectively, especially when the number of antennas at the secondary transceiver is large, while the secondary link can achieve a significant rate. Power is another precious resource besides spectrum. Instead of spectrum efficiency, energy-efficient spectrum sharing focuses on the energy efficiency (EE) optimization of the secondary transmission. The EE of the secondary transmission is defined as the ratio of the achievable secondary rate and the secondary power consumption, which includes both the transmit power and the circuit power at the secondary transmitter. For simplicity, the circuit power is modeled as a constant. Specifically, the EE of a MIMO secondary link in underlay spectrum sharing is studied. Three transmission strategies are introduced based on the primary rate requirement and the channel conditions. Rate splitting and successive decoding are deployed at the secondary transmitter and receiver, respectively, when it is feasible, and otherwise single-user decoding is deployed at the secondary receiver. For each case, optimal transmit covariance matrices at the secondary transmitter are obtained, to maximize the EE of the secondary transmission while satisfying the primary rate requirement and the secondary power constraint. Based on this, an energy-efficient resource allocation algorithm is proposed. Numerical results show that MIMO underlay spectrum sharing with EE optimization can achieve a significantly higher EE compared with MIMO underlay spectrum sharing with rate optimization, at certain SNRs and with certain circuit power, at the cost of the achievable secondary rate, while saving the transmit power. With rate splitting at the secondary transmitter and successive decoding at the secondary receiver if feasible, a significantly higher EE can be achieved compared with the case when only single-user decoding is deployed at the secondary receiver. Moreover, the EE of a MIMO secondary link in overlay spectrum sharing is studied, where the secondary transmitter has non-causal knowledge of the primary message and employs DPC to obtain an interference-free secondary link. Energy-efficient precoding and power allocation is obtained to maximize the EE of the secondary transmission while satisfying the primary rate requirement and the secondary power constraint. Numerical results show that MIMO overlay spectrum sharing with EE optimization can achieve a significantly higher EE compared with MIMO overlay spectrum sharing with rate optimization, at certain SNRs and with certain circuit power, at the cost of the achievable secondary rate, while saving the transmit power. MIMO overlay spectrum sharing with EE optimization can achieve a higher EE compared with MIMO underlay spectrum sharing with EE optimization
Aufgrund der rasanten Entwicklung im Bereich der drahtlosen Kommunikation und der ständig steigenden Nachfrage nach mobilen Anwendungen ist die Knappheit von Frequenzbändern ein entscheidender Engpass, der die Einführung neuer Funktechnologien behindert. Die gemeinsame Benutzung von Frequenzen (Spektrum-Sharing) durch primäre und sekundäre Nutzer ist eine Möglichkeit, die Effizienz bei der Verwendung des Spektrums zu verbessern. Bei der Methode des Underlay-Spektrum-Sharing sendet der sekundäre Nutzer zeitgleich mit dem primären Nutzer unter der Einschränkung, dass für den primären Nutzer die erzeugte Interferenz unterhalb eines Schwellwertes liegt oder gewisse Anforderungen an die Datenrate erfüllt werden. In diesem Zusammenhang wird in der Arbeit insbesondere die Koexistenz von Mehrantennensystemen untersucht. Dabei wird für die primäre Funkverbindung der Fall mit mehreren Sendeantennen und einer Empfangsantenne (MISO) angenommen. Für die sekundäre Funkverbindung werden mehrere Sendeantennen und sowohl eine als auch mehrere Empfangsantennen (MISO/MIMO) betrachtet. Der primäre Sender verwendet Maximum-Ratio-Transmission (MRT) und der primäre Empfänger Einzelnutzerdecodierung. Für den sekundären Nutzer werden außerdem am Sender eine Datenratenaufteilung (rate splitting) und am Empfänger entweder eine sukzessive Decodierung – sofern sinnvoll – oder andernfalls eine Einzelnutzerdecodierung verwendet. Im Unterschied zur Methode des Underlay-Spektrum-Sharing kann der sekundäre Nutzer beim Verfahren des Overlay-Spektrum-Sharing die Kenntnis über die Nachrichten des primären Nutzers einsetzen, um die Übertragung sowohl der eigenen als auch der primären Nachrichten zu unterstützen. Das Wissen über die Nachrichten erhält er entweder nicht-kausal, d.h. vor der Übertragung, oder kausal, d.h. während der ersten Phase einer zweistufigen Übertragung. In der Arbeit wird speziell die Koexistenz von primären MISO-Funkverbindungen und sekundären MISO/MIMO-Funkverbindungen untersucht. Bei nicht-kausaler Kenntnis über die primären Nachrichten kann der sekundäre Sender beispielsweise das Verfahren der Dirty-Paper-Codierung (DPC) verwenden, welches es ermöglicht, die Interferenz durch die primären Nachrichten bei der Decodierung der sekundären Nachrichten am sekundären Empfänger aufzuheben. Da die Implementierung der DPC mit einer hohen Komplexität verbunden ist, kommt als Alternative auch eine lineare Vorcodierung zum Einsatz. In beiden Fällen verwendet der primäre Transmitter MRT und der primäre Empfänger Einzelnutzerdecodierung. Besitzt der sekundäre Nutzer keine nicht-kausale Kenntnis über die primären Nachrichten, so kann er als Gegenleistung für die Mitbenutzung des Spektrums dennoch die Übertragung der primären Nachrichten unterstützen. Hierfür leitet er die primären Nachrichten mit Hilfe der Amplify-And-Forward-Methode oder der Decode-And-Forward-Methode in einer zweitstufigen Übertragung weiter, währenddessen er seine eigenen Nachrichten sendet. Der primäre Nutzer passt seine Sendestrategie entsprechend an und kooperiert mit dem sekundären Nutzer, um die Anforderungen an die Datenrate zu erfüllen. Nicht nur das Spektrum sondern auch die Sendeleistung ist eine wichtige Ressource. Daher wird zusätzlich zur Effizienz bei der Verwendung des Spektrums auch die Energieeffizienz (EE) einer sekundären MIMO-Funkverbindung für das Underlay-Spektrum-Sharing-Verfahren analysiert. Wie zuvor wird für den sekundären Nutzer am Sender eine Datenratenaufteilung (rate splitting) und am Empfänger entweder eine sukzessive Decodierung oder eine Einzelnutzerdecodierung betrachtet. Weiterhin wird die EE einer sekundären MIMO-Funkverbindung für das Overlay-Spektrum-Sharing-Verfahren untersucht. Dabei nutzt der sekundäre Nutzer die nicht-kausale Kenntnis über die primären Nachrichten aus, um mittels DPC eine interferenzfreie sekundäre Funkverbindung zu erhalten

Lock-based resource sharing protocols for single processor systems are well understood and supported in programming languages such as Ada and the Real-Time Specification for Java, and in Real-Time Operating Systems, and those that conform to the Real-Time POSIX standard. In contrast, multiprocessor resource sharing protocols are still in their infancy with no agreed best practices, and yet current real-time programming languages and operating systems claim to be suitable for supporting multiprocessor applications. This thesis argues that, instead of supporting a single resource sharing protocol, a resource sharing framework should be provided that allows application-defined resource sharing protocols to be implemented. The framework should be flexible and adaptive so that a wide range of protocols with different design characteristics can be integrated and implemented effectively with minimum runtime overheads. The thesis reviews the currently available multiprocessor resource allocation policies and analyzes their applicability to the main industry standard real-time programming languages. It then proposes a framework that allows programmers to define and implement their own locking policy for monitor based concurrent control mechanisms. Instantiation of the framework is illustrated for the Real-Time Specification for Java and POSIX. A prototype implementation of the full framework for Ada is developed and evaluated.

Thesis (Ed. D.)--Illinois State University, 1995.
Title from title page screen, viewed May 15, 2006. Dissertation Committee: Edward R. Hines (chair), Thomas C. Campbell, Ronald S. Halinski, Connie J. Ley, Anita H. Lupo. Includes bibliographical references (leaves 133-138) and abstract. Also available in print.

Embedded systems are typically resource constrained, i.e., resources such as processors, I/O devices, shared buffers or shared memory can be limited for tasks in the system. Therefore, techniques that enable an efficient usage of such resources are of great importance. In the industry, typically large and complex software systems are divided into smaller parts (applications) where each part is developed independently. Migration towards multiprocessor platforms has become inevitable from an industrial perspective. Due to such migration and to efficient use of system resources, these applications eventually may be integrated on a shared multiprocessor platform. In order to facilitate the integration phase of the applications on a shared platform, the timing and resource requirements of each application can be provided in an interface when the application is developed. The system integrator can benefit from such provided information in the interface of each application to ease the integration process. In this thesis, we have provided the resource and timing requirements of each application in their interfaces for applications that may need several processors to be allocated on when they are developed. Although many scheduling techniques have been studied for multiprocessor systems, these techniques are usually based on the assumption that tasks are independent, i.e. do not share resources other than the processors. This assumption is typically not true. In this thesis, we provide an extension to such systems to handle sharing of resources other than processor among tasks. Two traditional approaches exist for multiprocessor systems to schedule tasks on processors. A recent scheduling approach for multiprocessors has combined the two traditional approaches and achieved a hybrid more efficient approach compared to the two previous one. Due to the complex nature of this scheduling approach the conventional approaches for resource sharing could not be used straight forwardly. In this thesis, we have modified resource sharing approaches such that they can be used in such hybrid scheduling systems. A second concern is that enabling resource sharing in the systems can cause unpredictable delays and variations in response time of tasks which can degrade system performance. Therefore, it is of great significance to improve the resource handling techniques to reduce the effect of imposed delays caused by resource sharing in a multiprocessor platform. In this thesis we have proposed alternative techniques for resource handling that can improve system performance for special setups.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2003.
Page 235 blank.
Includes bibliographical references (p. 232-234).
Efforts to share resources in collaborative pursuits are hindered by differing data representations, redundant applications, and software incompatibilities. Members of a collaborative effort often span different computational environments and the heterogeneity of contexts disrupts software interoperability. Sharing computational resources has become the focus of many research efforts. Efforts in the 1980s led to the Component Object Model (COM) [Williams, 1998a, 1998b, 1990] and the Common Object Request Broker (CORBA) architectures [Offall et al 1996; OMG, 2003]. In the 1990s both technologies were extended for network support. In recent years, Ian Foster, has phrased the distributed computing problem in terms of sharing computational resources. The grid problem is, "coordinated resource sharing and problem solving in dynamic, multi-institutional virtual organizations", "to support collaborative problem solving in industry, science, and engineering in a data rich environment". [Foster et al, 2001] This work presents a new resource sharing platform architecture for information products that leverages the lessons learned from physical product platforms, the concepts of web services, and grid computing. The platform developed in this thesis integrates the contributions of these three areas into a system that is shown to be more efficient and effective at producing software products.
by Abel Sanchez.
Ph.D.

Recent years have seen a significant interest in quantitative measurements of licensed and unlicensed spectrum use. Several research groups, companies and regulatory bodies have conducted studies of varying times and locations with the aim to capture the over- all utilisation rate of spectrum. The studies have shown that large amount of allocated spectrum are under-utilised, and create the so called "spectrum holes", resulting in a waste of valuable frequency resources. In order to satisfy the requirements of increased demands of spectrum resources and to improve spectrum utilisation, dynamic spectrum sharing (DSS) is proposed in the literature along with cognitive radio networks (CRNs). DSS and CRNs have been studied from many perspectives, for example spectrum sensing to identify the idle channels has been under the microscope to improve detection proba- bility. As well as spectrum sensing, the DSS performance analysis remains an important topic moving towards better spectrum utilisation to meet the exponential growth of traffic demand. In this dissertation we have studied both techniques to achieve different objectives such as enhancing the probability of detection and spectrum utilisation. In order to improve spectrum sensing decisions we have proposed a cooperative spec- trum sensing scheme which takes the propagation conditions into consideration. The proposed location aware scheme shows an improved performance over conventional hard combination scheme, highlighting the requirements of location awareness in cognitive radio networks (CRNs). Due to the exponentially growing wireless applications and services, traffic demand is increasing rapidly. To cope with such growth wireless network operators seek radio resource cooperation strategies for their users with the highest possible grade of service (GoS). However, it is difficult to fathom the potential benefits of such cooperation, thus we propose a set of analytical models for DSS to analyse the blocking probability gain and degradation for operators. The thesis focuses on examining the performance gains that DSS can entail, in different scenarios. A number of dynamic spectrum sharing scenarios are proposed. The proposed models focus on measuring the blocking probability of secondary network operators as a trade-off with a marginal increase of the blocking probability of a primary network in return of monetary rewards. We derived the global balance equation and an explicit expression of the blocking probability for each model. The robustness of the proposed analytical models is evaluated under different scenarios by considering varying tra�c intensities, different network sizes and adding reserved resources (or pooled capacity). The results show that the blocking probabilities can be reduced significantly with the proposed analytical DSS models in comparison to the existing local spectrum access schemes. In addition to the sharing models, we further assume that the secondary operator aims to borrow spectrum bandwidths from primary operators when more spectrum resources available for borrowing than the actual demand considering a merchant mode. Two optimisation models are proposed using stochastic optimisation models in which the secondary operator (i) spends the minimum amount of money to achieve the target GoS assuming an unrestricted budget or (ii) gains the maximum amount of profit to achieve the target GoS assuming restricted budget. Results obtained from each model are then compared with results derived from algorithms in which spectrum borrowings were random. Comparisons showed that the gain in the results obtained from our proposed stochastic optimisation model is significantly higher than heuristic counterparts. A post-optimisation performance analysis of the operators in the form of analysis of blocking probability in various scenarios is investigated to determine the probable per- formance gain and degradation of the secondary and primary operators respectively. We mathematically model the sharing agreement scenario and derive the closed form solution of blocking probabilities for each operator. Results show how the secondary and primary operators perform in terms of blocking probability under various offered loads and sharing capacity. The simulation results demonstrate that at most trading windows, the proposed opti- mal algorithms outperforms their heuristic counterparts. When we consider 80 cells, the proposed profit maximisation algorithm results in 33.3% gain in net pro�t to the secondary operators as well as facilitating 2.35% more resources than the heuristic ap- proach. In addition, the cost minimisation algorithm results in 46.34% gain over the heuristic algorithm when considering the same number of cells (80).

Dans la thèse présente, nous proposons plusieurs contributions pour améliorer la performance dans les réseaux d'ordinateurs. Les résultats obtenus concernent les problèmes de partage de ressources dans les routeurs d'Internet, les serveurs Web et les systèmes d'exploitation. Nous étudions quelques algorithmes qui diminuent le temps moyen de séjour dans le système avec un partage des ressources efficace et qui fournissent la possibilité d'introduire la différentiation entre les flux dans les réseaux. Nous montrons l'efficacité des algorithmes proposés et nous étudions la possibilité de leur application dans les files d'attente de routeurs. Nous notons les résultats obtenus les plus importants. Pour la politique de service à temps partagé à deux niveaux avec le temps de service hyper-exponentielle avec deux phases nous trouvons une expression de l'approximation de la valeur de seuil optimal qui minimise le temps moyen de séjour dans le système. Avec les résultats de simulations nous montrons que la politique TLPS améliore la performance dans le système quand la valeur approchée du seuil est utilisé. Nous appliquons le résultat de Gittins pour caractériser la politique optimale pour l'ordonnancement dans une file d'attente multi-classe avec un serveur unique. La politique trouvé minimise le temps moyen de séjour dans le système entre toutes les politiques non-anticipatoires. Nous introduisons un nouvel algorithme d'élimination de paquets sensible aux flux pour les routeurs de l'Internet, qui améliore la performance du réseau et l'équité entre les flux. Dans la thèse présente, nous proposons plusieurs contributions pour améliorer la performance dans les réseaux d'ordinateurs. Les résultats obtenus concernent les problèmes de partage de ressources dans les routeurs d'Internet, les serveurs Web et les systèmes d'exploitation. Nous étudions quelques algorithmes qui diminuent le temps moyen de séjour dans le système avec un partage des ressources efficace et qui fournissent la possibilité d'introduire la différentiation entre les flux dans les réseaux. Nous montrons l'efficacité des algorithmes proposés et nous étudions la possibilité de leur application dans les files d'attente de routeurs. Nous notons les résultats obtenus les plus importants. Pour la politique de service à temps partagé à deux niveaux avec le temps de service hyper-exponentielle avec deux phases nous trouvons une expression de l'approximation de la valeur de seuil optimal qui minimise le temps moyen de séjour dans le système. Avec les résultats de simulations nous montrons que la politique TLPS améliore la performance dans le système quand la valeur approchée du seuil est utilisé. Nous appliquons le résultat de Gittins pour caractériser la politique optimale pour l'ordonnancement dans une file d'attente multi-classe avec un serveur unique. La politique trouvé minimise le temps moyen de séjour dans le système entre toutes les politiques non-anticipatoires. Nous introduisons un nouvel algorithme d'élimination de paquets sensible aux flux pour les routeurs de l'Internet, qui améliore la performance du réseau et l'équité entre les flux
In the current thesis we propose several new contributions to improve the performance of computer networks. The obtained results concern the resource sharing problems in the Internet routers, Web servers and operating systems. We study several stochastic scheduling algorithms which decrease the mean waiting time in the system with efficient resource sharing and provide the possibility to introduce the Quality of Service and flow differentiation to the networks. We show the effectiveness of the proposed algorithms and study the possibility of their implementation in the router queues. The most important obtained results are the following. For the Two Level Processor Sharing scheduling discipline with the hyper-exponential job size distribution with two phases we find an approximation for the optimal value of the threshold that minimizes the expected sojourn time. With the simulation results (NS-2) we show that TLPS improves significantly the system performance when the found approximation of the optimal threshold is used. We study the Discriminatory Processor Sharing policy and show the monotonicity of the expected sojourn time in the system depending on the weight vector under certain conditions on the system. We apply the Gittins optimality result to characterize the optimal scheduling discipline in a multi-class single server queue. The found policy minimizes the mean sojourn time in the system between all non-anticipating scheduling policies. In several cases of practical interest we describe the policy structure and provide the simulation results (NS-2). For the the congestion control problem in the networks we propose a new flow-aware algorithm to improve the fair resource sharing of the bottleneck capacity

Thesis (M.S.)--University of California, San Diego, 2009.
Title from first page of PDF file (viewed October 20, 2009). Available via ProQuest Digital Dissertations. Includes bibliographical references (p. 54-56).

Over the past ninety years, and more so over the recent twenty years, Library and Information Science schools in China have done a lot of work in collaborating and resource sharing. These activities consists of establishing LIS schools, training of teachers, compilation of teaching materials, change of names, application for the authority to enroll graduates and conferring degrees both of master and doctor, and academic exchanges. The demands of society and the policies of the government are important factors promoting the collaboration and resource sharing. Academic exchanges, such as academic meetings, ex-change visits and research papers, are the main channels for LIS schools to collaborate and share re-sources with each other.

Dans cette thèse, nous étudions le contrôle dynamique des systèmes de partage de ressources qui se posent dans divers domaines : réseaux de gestion des stocks, services de santé, réseaux de communication, etc. Nous visons à allouer efficacement les ressources disponibles entre des projets concurrents, selon certains critères de performance. Ce type de problème est de nature stochastique et peut être très complexe à résoudre. Nous nous concentrons donc sur le développement de méthodes heuristiques performantes. Dans la partie I, nous nous plaçons dans le cadre des Restless Bandit Problems, qui est une classe générale de problèmes d’optimisation dynamique stochastique. Relaxer la contrainte de trajectoire dans le problème d’optimisation permet de définir une politique d’index comme heuristique pour le modèle contraint d’origine, aussi appelée politique d’index de Whittle. Nous dérivons une expression analytique pour l’index de Whittle en fonction des probabilités stationnaires de l’état dans le cas où les bandits (ou projets) suivent un processus de naissance et de mort. D’une part, cette expression nécessite la vérification de plusieurs conditions techniques, d’autre part elle ne peut être calculée explicitement que dans certains cas spécifiques. Nous prouvons ensuite, que dans le cas particulier d’une file d’attente multi-classe avec abandon, la politique d’index de Whittle est asymptotiquement optimale aussi bien pour les régimes à faible trafic comme pour ceux à fort trafic. Dans la partie II, nous dérivons des heuristiques issues de l’approximation des systèmes stochastiques de partage de ressources par des modèles fluides déterministes. Nous formulons dans un premier temps une version fluide du problème d’optimisation relaxé que nous avons introduit dans la partie I, et développons une politique d’index fluide. L’index fluide peut toujours être calculé explicitement et surmonte donc les questions techniques qui se posent lors du calcul de l’index de Whittle. Nous appliquons les politiques d’index de Whittle et de l’index fluide à plusieurs cas : les fermes de serveurs éco-conscients, l’ordonnancement opportuniste dans les systèmes sans fil, et la gestion de stockage de produits périssables. Nous montrons numériquement que ces politiques d’index sont presque optimales. Dans un second temps, nous étudions l’ordonnancement optimal de la version fluide d’une file d’attente multi-classe avec abandon. Nous obtenons le contrôle optimal du modèle fluide en présence de deux classes de clients en concurrence pour une même ressource. En nous appuyant sur ces derniers résultats, nous proposons une heuristique pour le cas général de plusieurs classes. Cette heuristique montre une performance quasi-optimale lorsqu’elle est appliquée au modèle stochastique original pour des charges de travail élevées. Enfin, dans la partie III, nous étudions les phénomènes d’abandon dans le contexte d’un problème de distribution de contenu. Nous caractérisons une politique optimale de regroupement afin que des demandes issues d’utilisateurs impatients puissent être servies efficacement en mode diffusion
In this thesis we study the dynamic control of resource-sharing systems that arise in various domains: e.g. inventory management, healthcare and communication networks. We aim at efficiently allocating the available resources among competing projects according to a certain performance criteria. These type of problems have a stochastic nature and may be very complex to solve. We therefore focus on developing well-performing heuristics. In Part I, we consider the framework of Restless Bandit Problems, which is a general class of dynamic stochastic optimization problems. Relaxing the sample-path constraint in the optimization problem enables to define an index-based heuristic for the original constrained model, the so-called Whittle index policy. We derive a closed-form expression for the Whittle index as a function of the steady-state probabilities for the case in which bandits (projects) evolve in a birth-and-death fashion. This expression requires several technical conditions to be verified, and in addition, it can only be computed explicitly in specific cases. In the particular case of a multi-class abandonment queue, we further prove that the Whittle index policy is asymptotically optimal in the light-traffic and heavy-traffic regimes. In Part II, we derive heuristics by approximating the stochastic resource-sharing systems with deterministic fluid models. We first formulate a fluid version of the relaxed optimization problem introduced in Part I, and we develop a fluid index policy. The fluid index can always be computed explicitly and hence overcomes the technical issues that arise when calculating the Whittle index. We apply the Whittle index and the fluid index policies to several systems: e.g. power-aware server-farms, opportunistic scheduling in wireless systems, and make-to-stock problems with perishable items. We show numerically that both index policies are nearly optimal. Secondly, we study the optimal scheduling control for the fluid version of a multi-class abandonment queue. We derive the fluid optimal control when there are two classes of customers competing for a single resource. Based on the insights provided by this result we build a heuristic for the general multi-class setting. This heuristic shows near-optimal performance when applied to the original stochastic model for high workloads. In Part III, we further investigate the abandonment phenomena in the context of a content delivery problem. We characterize an optimal grouping policy so that requests, which are impatient, are efficiently transmitted in a multi-cast mode

Allocating resources for applications is attributed to cost-efficiency measures only in the light of two other factors of paramount importance, namely application performance achieved and resource efficiency associated. Achieving satisfactory performance within QoS requirements is indeed the foremost objective to attain for any given application. However, the efficiency obtained for the relevant deployed resources is equally critical as it determines to what extent a resource allocation decision was comparable to optimality, and hence may be perceived cost-efficient in that regard. Achieving high application performance comes in conflict with maintaining high resource efficiency. The compromise between the two to seek a feasible trade-off at which a cost-efficient allocation can be claimed is without doubt a complex multi-dimensional problem as it directly has to deal with an adamant prime issue that is known as performance unpredictability. It is particularly raised in resource provisioning from large-scale clouds (whose infrastructure is virtualised and shared) due to factors mainly include: heterogeneity of cloud resources, workload uncertainty, and performance interference. This thesis attempts to optimise allocation decisions made for cloud-hosted applications against the challenge of performance unpredictability by improving their resource efficiency while ensuring that each application can satisfy its performance objectives in a cost-efficient deployment. To this end, we follow a holistic approach to present our contributions through which we address each factor of the aforementioned challenge when designing allocation mechanisms to achieve optimal allocations that are efficient performance-, utilisation-, and cost-wise. Firstly, we devise a resource allocation framework that exploits and thus benefits from heterogeneity of cloud resources such that application performance is predictable despite of being running on heterogeneous resources with varying computing capacities. Then, we address the long-standing problem of resource over-provisioning in cloud datacenters in response to workload uncertainty. Finally, we design and built a QoS-aware resource controlling system that enables coordinated execution amongst multiple applications on shared resources, with which a potential performance interference can be mitigated.

Abstract The aim of this thesis is to devise novel co-primary spectrum sharing (CoPSS) methods for future fifth generation (5G) networks and beyond. The target is to improve data rates of small cell networks (SCNs) in which mobile network operators (MNOs) share their dedicated frequency spectrum (spectrum pooling) or a common spectrum (mutual renting). The performance of the proposed methods is assessed through extensive system-level simulations. MNOs typically acquire exclusive usage rights for certain frequency bands and have little incentive to share spectrums with other operators. However, due to higher cost and spectrum scarcity at lower frequencies it is expected that efficient use of the spectrum in 5G networks will rely more on spectrum sharing than exclusive licenses. This is especially true for new higher candidate frequencies (> 6 GHz) that do not have a pre-existing spectrum regulation framework. In the first part of the thesis, we tackle the challenge of providing higher data rates within limited spectral resources. Each SCN MNO has its own dedicated spectrum, and each MNO defines a percentage of how much its spectrum it is willing to share. The idea of the proposed CoPSS algorithms is that the spectrum is dynamically shared among MNOs based on their spectrum utilization, which is shared among MNOs in the network. This way interference can be avoided and spectrum utilization is maximized. Unused resources are shared equally between overloaded MNOs for a given time instant. Thus, only short-term fairness among overloaded SCNs can be guaranteed. In the second part, we consider a multi-operator small cell network where MNOs share a common pool of radio resources. The goal is to ensure the long term fairness of spectrum sharing without coordination among small cell base stations. We develop a decentralized control mechanism for base stations using the Gibbs sampling based learning tool, which allocates suitable amount of the spectrum for each base station while avoiding interference from SCNs and maximizing the total network throughput. In the studied scenarios, we show the importance of coordination among MNOs when the dedicated spectrum is shared. However, when MNOs share a common spectrum, a decentralized control mechanism can be used to allocate suitable amounts of spectrum for each base station. The proposed algorithms are shown to be effective for different network layouts, by achieving significant data rate enhancements with a low overhead
Tiivistelmä Tämä väitöskirja keskittyy kehittämään uusia menetelmiä, joilla jaetaan taajuuksia useiden operaattoreiden kesken tulevista viidennen sukupolven verkoista alkaen. Päätavoite on parantaa tiedonsiirtonopeuksia sellaisissa piensoluverkoissa, joissa matkapuhelinoperaattorit jakavat joko heidän omia taajuusalueitaan tai heillä yhteisomistuksessa olevia taajuuksia. Kehitettyjen menetelmien suorituskykyä arvioidaan mittavien järjestelmätason simulointien avulla. Matkapuhelinoperaattorit tyypillisesti omistavat yksin tietyt taajuusalueet, eivätkä ole valmiita jakamaan niitä. On kuitenkin oletettu, että tulevaisuudessa matkapuhelinoperaattorit joutuvat jakamaan taajuuksia, koska taajuusalueet ovat kalliita ja niukkoja erityisesti matalilla taajuusalueilla. Korkeammat taajuusalueet (> 6 GHz) puolestaan muodostavat otollisen alustan tehokkaalle spektrin jaetulle käytölle, koska niillä ei ole vielä olemassa olevaa taajuussääntelyä. Väitöskirjan ensimmäisessä osassa keskitytään kasvattamaan tiedonsiirtonopeuksia kun jokainen matkapuhelinoperaattori omistaa oman taajuuskaistansa ja matkapuhelinoperaattorit määrittävät kuinka suuren prosentuaalisen osuuden ovat valmiita jakamaan. Esitettyjen algoritmien päätavoite on jakaa taajuuksia dynaamisesti matkapuhelinoperaattoreiden kesken. Algoritmeissa hyödynnetään tietoa matkapuhelinoperaattoreiden taajuuden käyttöasteesta, jonka matkapuhelinoperaattoritkommunikoivat toisilleen. Näin häiriö voidaan välttää ja taajuuden käyttö maksimoidaan. Käyttämättömät taajuudet jaetaan tasaisesti matkapuhelinoperaattorien kesken tietyllä ajanhetkellä. Näin voidaan taata lyhytaikainen oikeudenmukainen taajuuksien käyttö, mutta ei pitkäaikaista oikeudenmukaista taajuuksien käyttöä. Väitöskirjan toisessa osassa matkapuhelinoperaattorit jakavat yhteisomistuksessa olevia taajuuksia. Tavoitteena on saavuttaa pitkäaikainen taajuuksien oikeudenmukainen käyttö, kun piensoluverkot eivät kommunikoi keskenään. Työssä kehitetään piensoluverkoille hajautettu algoritmi, joka perustuu oppimistyökaluun Gibbs-näytteistys. Näin saadaan allokoitua jokaiselle tukiasemalle tarvittava määrä taajuusresursseja niin, että häiriö tukiasemien välillä minimoidaan ja koko piensoluverkon suorituskyky maksimoidaan. Tutkituissa skenaarioissa osoitetaan matkapuhelinoperaattoreiden välisen koordinaation tärkeys, kun jaetaan omia taajuusalueita. Toisaalta kun operaattorit jakavat yhteisomistuksessa olevia taajuuksia on mahdollista käyttää algoritmeja, joissa ei ole koordinaatiota matkapuhelinoperaattoreiden kesken. Väitöskirjassa vahvistetaan kehitettyjen algoritmien olevan tehokkaita ja sopivan monenlaisiin verkkoympäristöihin saavuttaen merkittäviä parannuksia tiedonsiirtonopeuteen ilman suuria kustannuksia

Designed to provide library service for two or more different groups of library users in one library facility, shared-use or joint-use libraries are a unique aspect of library resources sharing. Thirteen examples of shared-use library collections in shared or joint-use library facilities in Florida were examined in this investigation. Special focus was placed on the perceptions of librarians who work in these libraries in order to determine how well the libraries meet the information needs on users and how successful the libraries are in conserving financial resources as a result of combined collections. A design of a special resource collections for one of the institutions participating in a shared-use library was formulated to demonstrate the planning process for collections sharing. Guidelines and contractual agreements relative to collection development that exist between the various shared-use libraries in Florida were evaluated and used to develop a model for agreements and a mission statement for shared-use libraries. Four types of shared-use library facilities in Florida were included in the study: community college/school libraries, community college/public libraries, community college/university libraries and school/public libraries.

Les systèmes multi-tâches temps-réels deviennent de plus en plus répandus de nos jours. La correction des systèmes multi-tâches est difficile à assurer, pourtant, la correction est critique pour les logiciels temps-réels. La vérification formelle aide à trouver les erreurs potentielles. Les conflits de partage de ressources qui peuvent produire une incohérence des données sont une sorte d'erreurs. Une solution est le verrouillage exclusif des ressources partagées qui peut mener à des temps d'exécution difficile à prédire, ou à l'interblocage dans le pire cas. La vérification des programmes est souvent effectuée par model checking. Un formalisme répandu de model checking des programmes temps-réels sont les automates temporisés. Ils permettent de vérifier certaines propriétés temporelles dans le modèle du programme et de trouver la séquence d'actions qui mènent à l'erreur. Il existe des algorithmes de vérification effectives pour des automates temporisés qui sont réalisés dans des outils de model checking largement utilisés. Nous avons développé un outil pour l'analyse statique de programmes Java multi-tâches qui trouve des conflits de partage de ressources possibles. Les programmes Java sont annotés avec des informations temporelles, et le modèle du programme est construit, en se basant sur les annotations. Le modèle est un système d'automates temporisés qui est vérifié par le model checker Uppaal. Des conflits de partage de ressources possibles sont trouvés par la vérification. Nous avons développé une étude de cas pour illustrer cette approche. L'analyse est complète: lorsqu'un conflit de partage de ressources peut apparaître dans un programme Java, il est détecté par notre analyse. Le modèle abstrait peut aussi sortir des alertes "faux positifs" qui ne correspondent pas à une configuration accessible dans le programme Java original. Pour s'assurer que la traduction des programmes Java vers des automates temporisés est correcte, nous avons formalisé la traduction dans l'assistant de preuves Isabelle. Nous avons prouvé que la traduction préserve la correspondance entre le programme et son modèle. Pour cela, nous avons développé une sémantique formelle de Java multi-tâche avec des annotations et des automates temporisés. Les preuves montrent que le modèle simule le comportement du programme Java original. Cela veut dire que chaque pas de la sémantique du code Java a une séquence de pas correspondante dans le modèle qui a le même effet sur l'état, c. à. D. Des valeurs des variables, temps ou objets verrouillés. Le code vérifié de traduction est généré à partir de la traduction formalisée en utilisant le générateur de code d'Isabelle. Puis notre outil utilise le code vérifié pour générer le modèle d'un programme Java
Multithreaded real-time systems become widespread nowadays. Correctness is critical for real-time applications but it is difficult to ensure by usual methods like testing. Formal verification helps to find possible errors. One kind of errors are resource sharing conflicts which lead to data corruption. A common solution is exclusive locking which can lead to unpredictable delays in execution or even deadlocks in the worst case. Program verification is often done by model checking. A popular model checking formalism for real-time programs are timed automata. It allows to verify certain timing properties in a model of a program and to find a sequence of actions which lead to an error. There exist effective verification algorithms for timed automata which are implemented in widely used model checking tools. We have developed a tool for static analysis of multithreaded Java programs which finds possible resource sharing conflicts. Java programs are annotated with timing information, and a model of the program is built based on the annotations. The model is a system of timed automata which is verified by the Uppaal model checker, and possible resource sharing conflicts are found. A case study has been developed to illustrate the approach. The analysis is complete: whenever a resource sharing conflict occurs in a Java program, it is detected by the our analysis. The abstract model may also output "false positive" warnings which do not correspond to a reachable configuration in the source Java program. In order to make sure that the abstraction of Java programs to timed automata is correct, we have formalized the translation is the Isabelle proof assistant. We have proved that the translation preserve correspondence between a program and its model. For this, we have developed a formal semantics both of multithreaded Java with annotations and of timed automata. The proofs show that the model simulates the behavior of the source Java program. This means that each semantic step made in the Java code has a corresponding sequence of steps in the model which has the same effect on the state, i. E. Variable values, time or locked objects. The verified code for translation is generated from the formalized translation using the Isabelle code generator. Then our tool uses the verified code to generate a model of a Java program

Human health care is heavily depending on the timely access to medical informtion. Since the serials/journals cover research and development news in the form of scientific articles, news items, new result of research, etc., meant for scientific community, the are proven prestigous communication vehicle amongst the scientists in the world. But, a number of surveys revealed that most relevant and frequently required medical journals are not available in most of the medical libraries in India. At present, there is no any union catalogue of medical periodicals available in India. Under the circumstances, this paper provides a conceptual plan of designing a web portal for sharing periodical holding details among medical libraries in India.

Nos maisons sont intelligentes grâce aux appareils fournissant des services (sécurité, efficacité énergétique,...). Des fournisseurs de services non fiables veulent profiter de la maison intelligente en développant des services hébergés dans une passerelle domotique embarquée. Cette passerelle doit être suffisamment robuste contre les problèmes logiciels. Partager les ressources de passerelle entre applications permet de fournir des services riches, mais provoque des risques de conflits de partage de ressources. Nous abordons le problème des conflits de partage des ressources dans la passerelle domotique, investiguant la prévention lorsque possible, et la détection et la résolution sinon. Notre première contribution «Jasmin» est un intergiciel pour développer, déployer et isoler les applications embarqués natives à base de composants et orientées services. Jasmin utilise les conteneurs Linux pour une isolation à faible coût. Notre seconde contribution «Incinerator» est un système dans la machine virtuelle Java (JVM) qui résout le problème des références obsolètes en Java, qui causent des fuites mémoire importantes en OSGi, augmentant ainsi les risques de conflits de partage de mémoire. Incinerator détecte et élimine les références obsolètes. Pour détecter les conflits de partage de mémoire, nous présentons la troisième contribution : système de surveillance mémoire dans la JVM. Le système compte précisément les ressources consommées pendant les interactions entre applications et fournit des statistiques d'utilisation de mémoire pour les différents fournisseurs de services partageant la passerelle
Our homes become smart thanks to devices providing services (security, energy efficiency,…). Untrusted service providers want to take advantage of the smart home by developing services hosted by an embedded smart home gateway. The gateway should be robust enough to handle software problems. Sharing resources of the gateway between service providers allows providing richer services but raises risks of resource sharing conflicts. We addresses the problem of resource sharing conflicts in the smart home gateway, by prevention when possible, and by detection and resolution otherwise. Our first contribution "Jasmin" is a middleware to develop, deploy and isolate native embedded component-based and service-oriented applications. Jasmin uses Linux containers for lightweight isolation. Our second contribution "Incinerator" is a subsystem in the Java Virtual Machine (JVM) aiming to resolve the problem of Java stale references, which cause significant memory leaks in an OSGi-based smart home gateway, hence increasing the risks of memory sharing conflicts. Incinerator detects and eliminates stale references. In order to detect memory sharing conflicts, we propose our third contribution: memory monitoring subsystem in the JVM. The system accurately accounts for resources consumed during cross-application interactions, and provides snapshots of memory usage statistics for the different service providers sharing the gateway

Thesis (M.S. in Management) Naval Postgraduate School, September 1996.
Thesis advisor(s): Joseph G. San Miguel, James A. Scaramozzino. "September 1996." Includes bibliographical references (p. 131-132). Also available online.

Future wireless networks will combine multiple radio technologies and subsystems, possibly managed by competing network providers. For such systems it may be advantageous to let the end nodes (terminals) make some or all of the resource management decisions. In addition to reducing complexity and costs, increasing redundancy, and facilitating more timely decisions; distributed resource sharing regimes can decouple the individual subsystems. Decoupled subsystems could be desirable both because competing operators can be business-wise separated and because it allows new technologies to be added (removed) in a modular fashion. However, distributed regimes can also lead to “selfish” wireless nodes who only try to maximize their own performance. The first part of this dissertation studies if selfish nodes can make efficient use of wireless resources, using multiaccess and network layers as examples. The related problems are formulated as noncooperative games between nodes. To maintain tractability nodes are confined to simple strategies that neither account for future payoffs nor allow for coordination. Yet, it is demonstrated that selfish nodes can achieve comparable performance to traditional protocols. These results should be interpreted as an argument in favor of distributed regimes. The second part of this dissertation evaluates the effects of multi-provider network architectures where users can roam freely across all networks. From a supply side perspective the benefits are improved path gain statistics and the fact that different networks may have non-overlapping busy hours. Several network configurations are analyzed and it is shown that cooperation between symmetric providers can yield significant capacity gains for both downlink and uplink; even if the providers have nearly collocated sites. When the providers have different site densities the gains from cooperation are reduced and the provider with a sparse network always gains more from cooperating. This suggests that initially, voluntary cooperation may be limited to some special cases. Lastly, the architecture is analyzed in a context where the providers compete for users on a per session basis by offering access at different prices. Although such architectures currently only exist in a few special cases, they could emerge in domestic markets where the costs to switch and search for new networks are low. Based on a game theoretic formulation it is shown that a competitive market for wireless access can be advantageous for both users and providers. The results presented suggest that the advantages of cooperation of competing providers occur in more than just a few cases.
QC 20100812

Pandemic influenza outbreaks have historically entailed significant societal and economic disruptions. Today, our quality of life is threatened by our inadequate preparedness for the imminent pandemic. The key challenges we are facing stem from a significant uncertainty in virus epidemiology, limited response resources, inadequate international collaboration, and the lack of appropriate science-based decision support tools. The existing literature falls short of comprehensive models for global pandemic spread and mitigation which incorporate the heterogeneity of the world regions and realistic travel networks. In addition, there exist virtually no studies which quantify the impact of resource sharing strategies among multiple countries. This dissertation presents three related models that contribute to filling the existing vacuum. The first model develops optimal capacity management strategies for multi-region pandemic surveillance. The second model estimates the pandemic propagation time from the onset to a likely pandemic export region, such as a major transportation hub. The model builds on a large-scale agent-based simulation and geographic information systems (GIS). The model is tested on a hypothetical outbreak in Mexico involving 155 regions and over 100 million people. The third model develops an empirical relationship to quantify the impact of various U.S. - Mexico antiviral sharing strategies under several pandemic detection and response scenarios.

Recently, there has been a massive growth in the number of mobile users and their traffic. The data traffic volume almost doubles every year. Mobile users are currently running multiple applications that require higher bandwidth which makes users so limited to the service providers' resources. Increasing the utilization of the existing spectrum can significantly improve network capacity, data rates and user experience. Spectrum sharing enables wireless systems to harvest under-utilized swathes of spectrum, which would vastly increase the efficiency of spectrum usage. Making more spectrum available can provide significant gain in mobile broadband capacity only if those resources can be aggregated efficiently with the existing commercial mobile system resources. Carrier aggregation (CA) is one of the most distinct features of 4G systems including Long Term Evolution Advanced (LTE-Advanced). In this dissertation, a resource allocation with carrier aggregation framework is proposed to allocate multiple carriers resources optimally among users with elastic and inelastic traffic in cellular networks. We use utility proportional fairness allocation policy, where the fairness among users is in utility percentage of the application running on the user equipment (UE). A resource allocation (RA) with CA is proposed to allocate single or multiple carriers resources optimally among users subscribing for mobile services. Each user is guaranteed a minimum quality of service (QoS) that varies based on the user's application type. In addition, a resource allocation with user discrimination framework is proposed to allocate single or multiple carriers resources among users running multiple applications. Furthermore, an application-aware resource block (RB) scheduling with CA is proposed to assign RBs of multiple component carriers to users' applications based on a utility proportional fairness scheduling policy. We believe that secure spectrum auctions can revolutionize the spectrum utilization of cellular networks and satisfy the ever increasing demand for resources. Therefore, a framework for multi-tier dynamic spectrum sharing system is proposed to provide an efficient sharing of spectrum with commercial wireless system providers (WSPs) with an emphasis on federal spectrum sharing. The proposed spectrum sharing system (SSS) provides an efficient usage of spectrum resources, manages intra-WSP and inter-WSP interference and provides essential level of security, privacy, and obfuscation to enable the most efficient and reliable usage of the shared spectrum. It features an intermediate spectrum auctioneer responsible for allocating resources to commercial WSPs' base stations (BS)s by running secure spectrum auctions. In order to insure truthfulness in the proposed spectrum auction, an optimal bidding mechanism is proposed to enable BSs (bidders) to determine their true bidding values. We also present a resource allocation based on CA approach to determine the BS's optimal aggregated rate allocated to each UE from both the BS's permanent resources and winning auctioned spectrum resources.
Ph. D.

This thesis describes a research study which investigated on-line communities based around Free and Open Source Software (FOSS) support and development. Specifically, the study examined how knowledge and resources are shared within these communities. Emphasis was placed on the issues of organisation and governance of these communities, collaboration, and the motivation of the participants involved. The research was carried out from an interpretive philosophical perspective and was therefore exploratory in nature, focusing on the perspectives of FOSS community participants. Following an in-depth literature review on the topics of FOSS and Knowledge Management, a multi-method approach was employed using three data collection techniques; an on-line questionnaire targeting participants in FOSS interest groups and communities, interviews with community participants and observation of two FOSS communities. The results of the research have revealed interesting findings relating to the social, managerial and technological mechanisms which facilitate knowledge transfer and creation in FOSS communities, and the important role that leadership styles, participant motivations, organisational structures and cultures, degrees of formality, relationships between participants and the use of information technology have to play in the success or failure of FOSS projects and communities. The research has shown that extremely strict or relaxed forms of leadership are likely to cause problems in a project and community, that a wide array of motivational factors drive participants, that many and varied forms of organisational structure and cultures exist, often influenced by leadership styles, that levels of formality in a community can have significant effects on knowledge sharing and collaboration, that social interaction acts as a foundation for FOSS activities but has little significance beyond that, and that to a certain extent, disagreements and arguments between participants and even project forking can be beneficial to a FOSS project and community. A generic finding was that FOSS communities vary considerably, based on the factors described above. This research therefore goes some way towards creating a generic model of FOSS communities and projects and specifies a number of 'recipes' for project and/or community success.

This research is aimed towards the design and planning of an agricultural library and information network in China. Systems approach is applied to the construction of descriptive, mathematical and hybrid (logical) models in the design phase of the system development cycle. Four major conventional network functions are chosen as core functions to be designed in detail. A number of procedures and issues are identified for both overall network and individual function design. The embodiment of the design is based on the particular context to which it relates. The results of the design arc presented by either descriptive, or mathematical or hybrid (logical) models, decided by the categories of issues (quantitative or qualitative, or hybrid). The impacts of new technologies are explored and three alternative programmes, dependent on the technologies to be applied, arc defined. The cost-effectiveness-benefits of the services as overall criteria, and AHP (Analytical Hierarchy Process) as an processing tool, help determine 1) which program will be run, computerized or non-computerized (by cost-benefit analysis}; and 2) for a particular program, the resource allocations (mainly budgets) among co-operative activities and the resource allocations within the activity, i.e. two-level allocations. Zhejiang province, one of 29 provinces in the country, is taken as an example of regional (provincial) network model. Twenty-eight nodes Iron: five sectors and three levels, plus more potential nodes, will be configured hierarchically within the respective sectors and, in decentralised mode among sectors, in terms of network management. But, in terms of information flow and transaction, the configuration will be a mixed one. The purposes of data collection arc identified at four stages of network planning, i.e. investigation of situation, theory-testing, explanation of model and prediction. A number of investigations were made to fulfil the objectives of data collection. The descriptions of those investigations are given and the results arc discussed. The barriers to data collection confronted in Chinese circumstances are presented. Statistical analyses are carried out for certain types of data 1) to seek the conformity with the empirical assumptions, 2) to help set objective measures, 3) to estimate parameters and co-efficiency, and 4) to derive some mean, average and unit values. The research has focused on the organisational aspects of networking. However, the macro-consideration of technology is inevitable since it is a time of technological change. The latter stages of mathematical modelling, i.e. optimisation, prediction and validation are left until more empirical data become available. Nevertheless, it is possible for the author to make recommendations about the development of agricultural library and information networks in China.