Thesis (Ph. D.)--State University of New York at Binghamton, Computer Science Department, 2006. / Includes bibliographical references.

[pt] Este trabalho considera o uso de um protocolo determinístico de acesso ao meio para transmissão eficiente de tráfegos assimétricos, através de um modo de operação TDD. Este modo é uma das opções selecionadas para adoção em sistemas celulares de terceira geração. São apresentados e analisados diferentes protocolos de acesso ao meio sendo um destes escolhido para ser implementado e ter o seu desempenho estudado. Diferentes modelos estatísticos para diversos tipos de tráfego assimétricos são considerados. Em seguida são discutidos os conceitos de qualidade de serviço (QoS) e os parâmetros que devem ser controlados.Continuando o trabalho são analisados detalhadamente: o protocolo escolhido, a maneira como este foi adaptado para aquele modo de operação e as medidas de desempenho que devem ser realizadas. Finalmente os resultados para cada tipo de tráfego individualmente e em conjunto são apresentados. / [en] This work has the objective of adapting a deterministic access protocol to the TDD mode of operation adopted as one of the third generation technologies in order to provide transmission of asymmetric traffic in a more efficient way. Different access methods are presented and analyzed and one of them is selected to be simulated and have its performance verified. Realistic asymmetric traffic models are discussed and actually implemented. Minimum requirements for Quality of Service for different traffics considered are introduced. The Quality of Service analysis made is focused on the minimum requirements of those traffic models. Detailed analysis of the chosen protocol is made in addition to its adaptation to the proposed situation. Finally, the results are presented showing the response of the protocol to each one of the traffic models considered and also to the situation when they are present simultaneously.

STANAG 5066 Edition 2 is a node-to-node protocol developed by NATO in order to communicate via HF media. IP integration is made to be able to spread the use of STANAG 5066 protocol. However, this integration made the communication much slower which is already slow. In order to get faster the speed and communicate within single-frequency multi-node network, HFTRP, which is a derivative of WTRP, is developed. This protocol is in two parts, first is a message design for management tokens exchanged by communicating nodes, and second is the algorithms used to create, maintain, and repair the ring of nodes in the network. Scope of this thesis is to find out a faster ring setup, growing procedure and to implement. Beside, finding optimum values of tuning parameters for HFTRP is also in the scope of this thesis.

Existing electronic markets are fragmented in the sense that each is an information island. The interoperation of product information between them is difficult especially in semantics communication. This prevents the formation of global electronic markets and the lowering distribution cost through market globalisation. The traditional and contemporary ap-proaches of product standardisation and ontology mediation could solve the problem only if all markets could adopt the same product standards, or mediation systems could mediate all heterogeneous standards and markets without semantic conflicts. However, problems generally exist in adopting a universal standard or mediating all markets through existing mediation systems. A reflection of the issue is that there are millions of ad hoc electronic product catalogues (EPCs) situated in small and medium sized enterprises (SMEs), where each EPC is a semantic community, often not aware of standards and mediation systems due to its ad hoc nature. This thesis focuses on the semantic integration of autonomous ad hoc EPCs, which are semantically inconsistent with each other. Firstly, a novel Collaborative Concept Exchange (CONEX) approach is developed for the se-mantic integration of ad hoc EPCs. Using this approach, a PRODUCT MAP is first built based on the theories of semiotic analysis and market segmentation. It functions as an analytical framework to articulate ad hoc EPCs, and answers the questions: what are the general char-acteristics of ad hoc EPCs, what are their heterogeneous relations, and how they are unevenly distributed in fragmented electronic markets. Within this framework, an abstract representa-tion of ad hoc EPCs is proposed using the articulated elements that are simple and manipu-lable. Major contributions of this framework include: the models of the abstract representa-tion of ad hoc EPCs on their structures, concepts and contexts; the semantic integration conditions of heterogeneous ad hoc EPCs; and a ConexNet of market network topology that captures the characteristics of ad hoc EPCs that are unevenly distributed in fragmented elec-tronic markets. Secondly, a three-layer CONEX information model is proposed to integrate ad hoc EPCs based on the PRODUCT MAP, which provides a trichotomy of systems, designers and users. The strategy behind the model is the separation of structure from concept and context, and hence they can be independently managed to resolve semantic conflicts between ad hoc EPCs. The major contributions of this model include the CONEX framework, collaboration mechanism and context transformation. The CONEX framework presents a formal characteri-sation and reconstruction of the structures of ad hoc EPCs based on a CONEX structure model and a CONEX grammar. It provides a formal specification for representing ad hoc EPCs including concept structure, classifier structure and mapping structure. The semantic conflicts in designing the concepts of ad hoc EPCs are resolved by a collaboration mecha-nism based on a semantic consistency model. The collaboration mechanism includes three key procedures: replicating unique concept identifiers and translating concept definitions be-tween common concepts of common EPCs; localising common concepts to local EPCs; and globalising local concepts to common EPCs. Users in the CONEX information model are not involved in any integration activities. They are provided with automatic and accurate concept exchange services through a mechanism of context transformation, which is designed based on an algorithm called Heterogeneous Concept Transformation. The separate integration of structures, concepts and contexts of ad hoc EPCs guarantees that the requirements of flexi-bility, evolvability and exactness of semantic integration have been met. Thirdly, the feasibility and features of the Collaborative Concept Exchange approach have been demonstrated in a prototype implementation that provides the services of collaborative concept design for semantic conflict resolution, and heterogeneous concept transformation for accurate and automatic concept exchange between ad hoc EPCs. A key contribution in the implementation level is the independent representation of the CONEX framework called XML PRODUCT MAP (XPM). XPM provides a feature of platform independence by con-forming to the standards of W3C XML, Simple Object Access Protocol and Web Services Description Language in both document specification and document transport. It is also a demonstration that the generic CONEX structure model and CONEX grammar can be imple-mented in any specific language such as XML for the particular scenarios of semantic integra-tion. With the aid of a collection of XPM document templates, two components called Con-cept Collaborator and Concept Transformer of the CONEX prototype are implemented to demonstrate how concepts are collaboratively designed to resolve semantic conflicts and how concepts are automatically and accurately exchanged between autonomous, heterogeneous and distributed ad hoc EPCs.

[pt] O desempenho de protocolos de múltiplos acesso em redes de dados, no que diz respeito a parâmetros como vazão, retardado e probabilidade de rejeição de pacotes, representa um dos fatores primordiais na comparação entre diversos tipos de sistemas propostos, no sentido de se buscar uma otimização do uso do canal de transmissão. Tendo em vista a dificuldade de se fazer um modelo analítico que represente bem os protocolos existentes, utilizam-se, normalmente, formulações simplificadas para o cálculo dos parâmetros desejados, ou recorre-se a um modelo de simulação, que necessita de maior tempo de computação pra obtenção dos resultados. Com o objetivo de se obter uma análise mais precisa dos protocolos de múltiplo acesso utilizados em redes de dados foram desenvolvidos modelos a partir de um método proposto por S.M.Meerkov e J.T.Lim. estes modelos consideram estações com buffers transmitindo mensagens que possuem um ou mais pacotes em canais com retardo, utilizando a distribuição de probabilidades do tamanho destas mensagens. É proposta também a retirada da hipótese simplificadora usualmente feita em análises envolvendo o protocolo ALOHA- Segmentado, de que a primeira transmissão de cada pacote é também feita com retardo. Esta metodologia é novamente aplicada para modelar um protocolo híbrido, que combina transmissões utilizando o modo S- ALOHA e um modo de reserva. São apresentados, também, modelos e resultados de simulação para validação dos modelos analíticos propostos. / [en] The performance of multiple access protocols in data networks, whit respect to parameters like throughput, delay and probability of packet rejection, is one of the major factor when comparing different types of proposed systems during an optimization process of the transmission channel. Due to difficulties in developing an analitical model that can make a good representation of the existing protocols, usally simprified formulations are used to evauate the desired parameters, or instead, simulations models are created, requiting more time of CPU to obtain the results. Having the objective of obtaing a more precise analitical tool for evaluating the multiple access protocols used in data networks models have been developed, based on the method proposed by S.M.Meerkov and J.T.Lim. these models consider stations having buffers and transmitting messages with one or more packets through delay channels, according to the distribuition of probabilities of the size of these messages. It is also proposed a model which do not present the hypothesis ususally used to simplify the Slotted-ALOHA (S-ALOHA) protocol, with respect to the need of having a delayed first transmission of a packet. The reffered combines transmittions in S-ALOHA mode and in a reervation mode. Simulation models and results are also used for validation of the proposed analitical models.

[pt] O rápido desenvolvimento tecnológico que ocorreu na área de comunicações móveis e o surpreendente interesse por parte dos usuários geraram um crescimento da demanda maior que o esperado. A necessidade de atender essa demanda e de suportar novos serviços como áudio, vídeo e multimídia, vem motivando o estudo de novas tecnologias. Atualmente, um dos objetivos principais é o aumento da capacidade da interface rádio. Visando este objetivo, diversos métodos de acesso vêm sendo propostos. Neste trabalho será feita uma análise de três protocolos de acesso proposta para tecnologia TDMA: o PRMA (Packet Reservation Multiple Access), o RAMA (Resource Auction Multiple Access). Resultados numéricos comparando o desempenho dos protocolos RAMA e TRAMA não estavam disponíveis na literatura e serão apresentados. Baseando-se nestes resultados será proposta uma variação do RAMA, o F-RAMA (Fair Resource Auction Multiple Access). O desempenho do protocolo para transmissão de voz bem como a comparação com os outros protocolos serão apresentados. Será visto que o F-RAMA é um excelente candidato à transmissão de voz e bastante promissor para a tecnologia multimídia no ambiente móvel celular. / [en] The fast technological development that occurred in the mobile communications sector and the outstanding interest showed by the users resulted in na unexpected huge demand. The need to sypply this demand and to support new services such as audio, video and multimedia have motivated the study of new technologies. Nowadays, one of the greatest challenge is to increase the radio interface capacity. To meet this goal many access methods have been proposed. This work will analyse three access protocols proposed to TDMA technology: PRMA ( packet Reservation Multiple Access), RAMA (Resource Auction Multiple Access) and TRAMA ( Tree-search Resource Auction Multiple Acess), Numerical results comparing RAMA and TRAMA that were so far unavailable in the literature will be presented here. Based upon these results a variation of RAMA, F-RAMA ( Fair Resource Auction Multiple Access), will be proposed. The protocol perfomance for voice transmission and a comparison among the three will also be presented herein. The effect of the multimedia transmission over F-RAMA will be discussed. It will be show that F-RAMA is an excellent candidate for voice trasmission and a promising candidate for multimedia transmission in the mobile communication environment.

No description available.

This research considers the transmission of real-time data within a wireless local area network (WLAN). Exact and approximate analytic network evaluation techniques are examined. The suitability of using a given technique in a particular situation is discussed. Simulation models are developed to study the performance of our protocol RT-MAC (real-time medium access control). RT-MAC is a novel, simple, and elegant MAC protocol for use in transmitting real-time data in point to point ad hoc WLAN. Our enhancement of IEEE 802.11, RT-MAC, achieves dramatic reductions in mean delay, missed deadlines, and packet collisions by selectively discarding packets and sharing station state information. For example, in a 50 station network with a normalized offered load of 0.7, mean delay is reduced from more than 14 seconds to less than 45 ms, late packets are reduced from 76% to less than 1%, and packet collisions are reduced from 36% to less than 1%. Stations using RT-MAC are interoperable with stations using IEEE 802.11. In networks with both RT-MAC and IEEE 802.11 stations, significant performance improvements were seen even when more than half of the stations in the network were not RT-MAC stations. The effect of the wireless channel and its impact on the ability of a WLAN to meet packet deadlines is evaluated. It is found that, in some cases, other factors such as the number of stations in the network and the offered load are more significant than the condition of the wireless channel. Regression models are developed from simulation data to predict network behavior in terms of throughput, mean delay, missed deadline ratio, and collision ratio. Telemetry, avionics, and packetized voice traffic models are considered. The applicability of this research is not limited to real-time wireless networks. Indeed, the collision reduction algorithm of RT-MAC is independent of the data being transported. Furthermore, RT-MAC would perform equally well in wired networks. Incorporating the results of this research into existing protocols will result in immediate and dramatic improvements in network performance. / Ph. D.

The primary contributions to the area of electronic business integration, propounded by this thesis, are (in no particular order):  A novel examination of global Business-to-Business (B2B) interoperability in terms of a "multiplicity paradox" and of a "global electronic market-space" from a Complex Systems Science perspective.  A framework for an, integrated, global electronic market-space, which is based on a hierarchical, incremental, minimalist-business-pattern approach. A Web Services-SOA forms the basis of application-to-application integration within the framework. The framework is founded in a comprehensive study of existing technologies, standards and models for secure interoperability and the SOA paradigm. The Complex Systems Science concepts of "predictable structure" and "structural complexity" are used consistently throughout the progressive formulation of the framework.  A model for a global message handler (including a standards-based message-format) which obviates the common problems implicit in standard SOAP-RPC. It is formulated around the "standardized, common, abstract application interface" critical success factor, deduced from examining existing models. The model can be used in any collaboration context.  An open standards-based security model for the global message handler. Conceptually, the framework comprises the following:  An interoperable standardized message format: a standardized SOAP-envelope with standardized attachments (8-bit binary MIME-serialized XOP packages).  An interoperable standardized message-delivery infrastructure encompassing an RPC-invoked message-handler - a Web service, operating in synchronous and/or asynchronous mode, which relays attachments to service endpoints.  A business information processing infrastructure comprised of: a standardized generic minimalist-business-pattern (simple buying/selling), comprising global pre-specifications for business processes (for example, placing an order), standardized specific atomic business activities (e.g. completing an order-form), a standardized document-set (including, e.g. an order-form) based on standardized metadata (common nomenclature and common semantics used in XSD's, e.g. the order-form), the standardized corresponding choreography for atomic activities (e.g. acknowledgement of receipt of order-form) and service endpoints (based on standardized programming interfaces and virtual methods with customized implementations). / Theoretical Computing / PHD (INFORMATION SYSTEMS)

The primary contributions to the area of electronic business integration, propounded by this thesis, are (in no particular order):  A novel examination of global Business-to-Business (B2B) interoperability in terms of a "multiplicity paradox" and of a "global electronic market-space" from a Complex Systems Science perspective.  A framework for an, integrated, global electronic market-space, which is based on a hierarchical, incremental, minimalist-business-pattern approach. A Web Services-SOA forms the basis of application-to-application integration within the framework. The framework is founded in a comprehensive study of existing technologies, standards and models for secure interoperability and the SOA paradigm. The Complex Systems Science concepts of "predictable structure" and "structural complexity" are used consistently throughout the progressive formulation of the framework.  A model for a global message handler (including a standards-based message-format) which obviates the common problems implicit in standard SOAP-RPC. It is formulated around the "standardized, common, abstract application interface" critical success factor, deduced from examining existing models. The model can be used in any collaboration context.  An open standards-based security model for the global message handler. Conceptually, the framework comprises the following:  An interoperable standardized message format: a standardized SOAP-envelope with standardized attachments (8-bit binary MIME-serialized XOP packages).  An interoperable standardized message-delivery infrastructure encompassing an RPC-invoked message-handler - a Web service, operating in synchronous and/or asynchronous mode, which relays attachments to service endpoints.  A business information processing infrastructure comprised of: a standardized generic minimalist-business-pattern (simple buying/selling), comprising global pre-specifications for business processes (for example, placing an order), standardized specific atomic business activities (e.g. completing an order-form), a standardized document-set (including, e.g. an order-form) based on standardized metadata (common nomenclature and common semantics used in XSD's, e.g. the order-form), the standardized corresponding choreography for atomic activities (e.g. acknowledgement of receipt of order-form) and service endpoints (based on standardized programming interfaces and virtual methods with customized implementations). / Theoretical Computing / PHD (INFORMATION SYSTEMS)