Analysis of the Dynamic Service Flow Management Transactions Protocol for MAC IEEE 802.16. An Aproach

In this work the WiMax MAC Protocol for Dynamic Service Flow management and their transactions is analyzed by showing this several pitfalls of the specification and how this can affect the implementation of the protocol using Colored Petri Nets (CPNs). A detailed description of the protocol is developed at level of transactions it supports, and at level of service flows. The modeling and analysis of the protocol are important to improve the current specification and to support the reuse of the concepts in emerging networks. We show the potentialities of using a transaction oriented approach in the description of this kind of protocols. The contributions of this paper are focused on providing a clear description of the protocol, presentation of the model, validation and analysis of the model according to the generation of the Dynamic Service Flow management transactions protocol language, as well as the determination of regular expressions Language.Sociedad Argentina de Informática e Investigación Operativa (SADIO

Um novo escalonador com controle de admissão de conexão para o padrão IEEE 802.16 com garantia de limite de atraso

The IEEE 802.16 Working Group on Broadband Wireless Access is developing a standard for broadband wireless access networks in Metropolitan Area Network (MAN), also know as WiMAX. One of the features of the MAC (Media Access Control) layer is that it was designed to differentiate service among traffic categories with different multimedia requirements. Based on these assumptions and considering that the standard does not specify a scheduling algorithm, a new scheduler with admission control connection has been proposed based on Latency-Rate (LR) server theory and system characteristics specified by the standard for systems using the WirelessMAN-OFDM (Orthogonal Frequency Division Multiplexing) air interface. The proposed scheduling algorithm calculates the Time Frame (TF) in order to maximize the number of stations allocated in the system while guarantee the delay required for each user. Properties of this proposal have been investigated theoretically and through simulations. A set of simulations is presented with streams of Constant Bit Rate (CBR) and Variable Bit Rate (VBR) and performance comparisons with different delays and different TFs. The results showed that the upper limit of delay can be achieved by a variety of loads in the network, optimizing the bandwidth.O grupo de trabalho do IEEE 802.16 está desenvolvendo um padrão para redes de acesso banda larga sem fio em redes metropolitanas, também conhecido como WiMAX. Uma das características da camada MAC (Media Access Control) desse padrão, é que ela foi projetada para diferenciar o serviço entre as categorias de tráfego com diferentes requisitos de multimídia. Com base nessa premissa e considerando que a norma não especifica um algoritmo de escalonamento, um novo escalonador com controle de admissão de conexão foi proposto com base na teoria do servidor Latency-Rate (LR) e características do sistema especificadas pela norma para sistemas utilizando a interface aérea WirelessMAN-OFDM (Orthogonal Frequency Division Multiplexing). O algoritmo de escalonamento proposto calcula o tempo do quadro (TF - Time Frame) com o objetivo de maximizar o número de estações alocadas no sistema e ao mesmo tempo garantir o atraso solicitado para cada usuário. Propriedades desta proposta foram investigadas teoricamente e através de simulações. Um conjunto de simulações é apresentado com fluxos de taxa de bits constante (CBR - Constant Bit Rate) e taxa de bits variável (VBR - Variable Bit Rate) e as comparações de desempenho com diferentes atrasos (delay) e diferentes TFs. Os resultados mostraram que o limite de atraso superior pode ser alcançado por uma grande variedade de cargas na rede, com otimização da largura de banda

Programming techniques for efficient and interoperable software defined radios

Recently, Software-Dened Radios (SDRs) has became a hot research topic in wireless communications eld. This is jointly due to the increasing request of reconfigurable and interoperable multi-standard radio systems able to learn from their surrounding environment and efficiently exploit the available frequency spectrum resources, so realizing the cognitive radio paradigm, and to the availability of reprogrammable hardware architectures providing the computing power necessary to meet the tight real-time constraints typical of the state-of-art wideband communications standards. Most SDR implementations are based on mixed architectures in which Field Programmable Gate Arrays (FPGA), Digital Signal Processors (DSP) and General Purpose Processors (GPP) coexist. GPP-based solutions, even if providing the highest level of flexibility, are typically avoided because of their computational inefficiency and power consumption. Starting from these assumptions, this thesis tries to jointly face two of the main important issues in GPP-based SDR systems: the computational efficiency and the interoperability capacity. In the first part, this thesis presents the potential of a novel programming technique, named Memory Acceleration (MA), in which the memory resources typical of GPP-based systems are used to assist central processor in executing real-time signal processing operations. This technique, belonging to the classical computer-science optimization techniques known as Space-Time trade-offs, defines novel algorithmic methods to assist developers in designing their software-defined signal processing algorithms. In order to show its applicability some "real-world" case studies are presented together with the acceleration factor obtained. In the second part of the thesis, the interoperability issue in SDR systems is also considered. Existing software architectures, like the Software Communications Architecture (SCA), abstract the hardware/software components of a radio communications chain using a middleware like CORBA for providing full portability and interoperability to the implemented chain, called waveform in the SCA parlance. This feature is paid in terms of computational overhead introduced by the software communications middleware and this is one of the reasons why GPP-based architecture are generally discarded also for the implementation of narrow-band SCA-compliant communications standards. In this thesis we briefly analyse SCA architecture and an open-source SCA-compliant framework, ie. OSSIE, and provide guidelines to enable component-based multithreading programming and CPU affinity in that framework. We also detail the implementation of a real-time SCA-compliant waveform developed inside this modified framework, i.e. the VHF analogue aeronautical communications transceiver. Finally, we provide the proof of how it is possible to implement an efficient and interoperable real-time wideband SCA-compliant waveform, i.e. the AeroMACS waveform, on a GPP-based architecture by merging the acceleration factor provided by MA technique and the interoperability feature ensured by SCA architecture

Analysis of the Dynamic Service Flow Management Transactions Protocol for MAC IEEE 802.16. An Aproach

In this work the WiMax MAC Protocol for Dynamic Service Flow management and their transactions is analyzed by showing this several pitfalls of the specification and how this can affect the implementation of the protocol using Colored Petri Nets (CPNs). A detailed description of the protocol is developed at level of transactions it supports, and at level of service flows. The modeling and analysis of the protocol are important to improve the current specification and to support the reuse of the concepts in emerging networks. We show the potentialities of using a transaction oriented approach in the description of this kind of protocols. The contributions of this paper are focused on providing a clear description of the protocol, presentation of the model, validation and analysis of the model according to the generation of the Dynamic Service Flow management transactions protocol language, as well as the determination of regular expressions Language.Sociedad Argentina de Informática e Investigación Operativa (SADIO

Analysis of the Dynamic Service Flow Management Transactions Protocol for MAC IEEE 802.16. An Aproach

In this work the WiMax MAC Protocol for Dynamic Service Flow management and their transactions is analyzed by showing this several pitfalls of the specification and how this can affect the implementation of the protocol using Colored Petri Nets (CPNs). A detailed description of the protocol is developed at level of transactions it supports, and at level of service flows. The modeling and analysis of the protocol are important to improve the current specification and to support the reuse of the concepts in emerging networks. We show the potentialities of using a transaction oriented approach in the description of this kind of protocols. The contributions of this paper are focused on providing a clear description of the protocol, presentation of the model, validation and analysis of the model according to the generation of the Dynamic Service Flow management transactions protocol language, as well as the determination of regular expressions Language.Sociedad Argentina de Informática e Investigación Operativa (SADIO