39 research outputs found

    Controlling Reversibility in Reversing Petri Nets with Application to Wireless Communications

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    Petri nets are a formalism for modelling and reasoning about the behaviour of distributed systems. Recently, a reversible approach to Petri nets, Reversing Petri Nets (RPN), has been proposed, allowing transitions to be reversed spontaneously in or out of causal order. In this work we propose an approach for controlling the reversal of actions of an RPN, by associating transitions with conditions whose satisfaction/violation allows the execution of transitions in the forward/reversed direction, respectively. We illustrate the framework with a model of a novel, distributed algorithm for antenna selection in distributed antenna arrays.Comment: RC 201

    Reversible Computation: Extending Horizons of Computing

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    This open access State-of-the-Art Survey presents the main recent scientific outcomes in the area of reversible computation, focusing on those that have emerged during COST Action IC1405 "Reversible Computation - Extending Horizons of Computing", a European research network that operated from May 2015 to April 2019. Reversible computation is a new paradigm that extends the traditional forwards-only mode of computation with the ability to execute in reverse, so that computation can run backwards as easily and naturally as forwards. It aims to deliver novel computing devices and software, and to enhance existing systems by equipping them with reversibility. There are many potential applications of reversible computation, including languages and software tools for reliable and recovery-oriented distributed systems and revolutionary reversible logic gates and circuits, but they can only be realized and have lasting effect if conceptual and firm theoretical foundations are established first

    Reversible Computation: Extending Horizons of Computing

    Get PDF
    This open access State-of-the-Art Survey presents the main recent scientific outcomes in the area of reversible computation, focusing on those that have emerged during COST Action IC1405 "Reversible Computation - Extending Horizons of Computing", a European research network that operated from May 2015 to April 2019. Reversible computation is a new paradigm that extends the traditional forwards-only mode of computation with the ability to execute in reverse, so that computation can run backwards as easily and naturally as forwards. It aims to deliver novel computing devices and software, and to enhance existing systems by equipping them with reversibility. There are many potential applications of reversible computation, including languages and software tools for reliable and recovery-oriented distributed systems and revolutionary reversible logic gates and circuits, but they can only be realized and have lasting effect if conceptual and firm theoretical foundations are established first

    Energy efficiency analysis in wireless communication systems with reconfigurable RF

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    Orientador: Prof. Dr. André Augusto MarianoCoorientador: Prof. Dr. Glauber Gomes de Oliveira BranteTese (doutorado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia Elétrica. Defesa : Curitiba, 28/05/2021Inclui referências: p. 74-84Área de concentração: Sistemas EletrônicosResumo: Alta eficiˆencia energ'etica (EE) 'e crucial para aplicac¸ ˜oes da Internet das Coisas que operam remotamente, uma vez que os n'os sem fio s˜ao tipicamente alimentados por bateria. Diferentes t'ecnicas de diversidade espacial tais com o uso de m'ultiplas antenas (MIMO) nos n'os do transmissor e receptor, bem como o uso de comunicac¸ ˜ao cooperativa podem ser exploradas para melhorar a EE. Al'em disso, o uso de transceptores de r'adio frequˆencia (RF) reconfigur'aveis s˜ao considerados uma soluc¸ ˜ao interessante para sistemas com restric¸ ˜ao de energia, pois permitem alterar o seu ponto de funcionamento, bem como o seu consumo de potˆencia, adaptando-se aos diferentes requisitos de comunicac¸ ˜ao. Nessa tese, uma nova abordagem para economizar energia inclui no modelo do sistema de comunicac¸ ˜ao o uso de transceptores de RF reconfigur'aveis. Mais especificamente, os componentes envolvidos em nossa estrutura de otimizac¸ ˜ao de consumo de potˆencia s˜ao o amplificador de potˆencia (PA) no transmissor e o amplificador de baixo ru'?do (LNA) no receptor. Nosso objetivo 'e mostrar que os circuitos de RF baseados em operac¸ ˜oes mult'?modo podem melhorar significativamente a EE. Assim, realizamos uma selec¸ ˜ao conjunta dos melhores modos de operac¸ ˜ao para os circuitos do PA e do LNA para diferentes esquemas de transmiss˜ao em dois cen'arios de rede: i) comunicac¸ ˜ao n˜ao-cooperativa em que os n'os s˜ao equipados com m'ultiplas antenas, para a qual consideramos a selec¸ ˜ao de antenas (AS) e a decomposic¸ ˜ao por valores singulares (SVD); e ii) comunicac¸ ˜ao cooperativa em que os n'os s˜ao equipados com uma 'unica antena, para a qual consideramos decodificac¸ ˜ao incremental e encaminha (IDF) por rel'e. Em nosso primeiro cen'ario proposto, comparamos os circuitos reconfigur 'aveis do PA e do LNA com amplificadores de RF n˜ao-reconfigur'aveis do estado-da-arte dispon'?veis na literatura. Nesta comparac¸ ˜ao, ao explorar as caracter'?sticas dos amplificadores reconfigur'aveis de RF, mostramos uma melhora de EE de mais de 40% em distˆancias curtas para as comunicac¸ ˜oes MIMO. Ao comparar os esquemas MIMO, a t'ecnica AS apresenta melhor desempenho para distˆancias mais curtas, enquanto que o SVD permite transmiss˜oes mais longas, pois explora todas as antenas dispon'?veis. Al'em disso, a otimizac¸ ˜ao da eficiˆencia espectral contribui para aumentar ainda mais a EE. Por fim, investigamos o efeito do n'umero de antenas, em que a EE do AS sempre aumenta com o n'umero de antenas, enquanto que o SVD apresenta um n'umero 'otimo de antenas. Para o segundo cen'ario, propomos uma an'alise de EE para o esquema IDF, auxiliada por um canal de retorno para realizar a selec¸ ˜ao de rel'es. Al'em disso, comparamos o desempenho do IDF com os esquemas MIMO n˜ao-cooperativos. Os resultados mostram que uma melhor EE 'e obtida por meio de t'ecnicas de selec¸ ˜ao de antenas, principalmente quando aplicadas tanto no transmissor quanto no receptor. Tamb'em analisamos o impacto do rel'e na cooperac¸ ˜ao, uma vez que o n'o do rel'e opera apenas se necess'ario, a maior parte da carga de reconfigurabilidade 'e do rel'e, enquanto os modos de operac¸ ˜ao do PA e do LNA tendem a ser razoavelmente fixados nos n'os de origem e destino. Por fim, os resultados mostram que o n'umero de rel'es contribui para alcanc¸ar transmiss˜oes de longa distˆancia. Palavras-chave: Eficiˆencia Energ'etica, Transceptores de RF Reconfigur'aveis, Diversidade Espacial, M'ultiplas Antenas, Comunicac¸ ˜oes Cooperativas.Abstract: High energy efficiency (EE) is crucial for Internet of Things applications that operate remotely, since wireless nodes are typically battery-powered. Different spatial diversity techniques such as the use of multiple antennas (MIMO) at the transmitter and receiver nodes, as well as the use of cooperative communication can be exploited to improve the EE. In addition, the use of radio frequency (RF) transceivers are considered an interesting solution for powerrestricted systems, as they allow changing their operating point, as well as their power consumption, adapting to different communication requirements. In this thesis, a novel energy-saving approach includes in the communication system model the use of reconfigurable RF transceivers. More specifically, the components involved in our power consumption optimization framework are the power amplifier (PA) at the transmitter and the low noise amplifier (LNA) at the receiver. Our goal is to show that RF circuits based on multimode operation can significantly improve the EE. Thus, we perform a joint selection of the best operating modes for the PA and LNA circuits for different transmission schemes in two network scenarios: i) non-cooperative communication where the nodes are equipped with multiple antennas, for which we consider antenna selection (AS) and singular value decomposition (SVD) beamforming; and ii) cooperative communication where the nodes are equipped with single antenna, for which we consider incremental decode and forward (IDF) relaying. In our first proposed scenario, we compare the reconfigurable PA and LNA circuits with state-of-the-art non-reconfigurable RF amplifiers available in the literature. In this comparison, by exploiting the characteristics of reconfigurable RF amplifiers, we show an EE improvement of more than 40% at short distances for MIMO communications. When comparing MIMO schemes, the AS technique performs better for shorter distances, while the SVD allows for longer transmissions, as it exploits all available antennas. In addition, the optimization of the spectral efficiency contributes to further increase the EE. Finally, we investigate the effect of the number of antennas, in which the EE of AS always increases with the number of antennas, while SVD presents an optimal number of antennas. For the second scenario, we propose an EE analysis for the IDF scheme, aided by a feedback channel to perform relay selection. In addition, we compare the performance of the IDF with non-cooperative MIMO schemes. The results show that a better EE is obtained through antenna selection techniques, especially when applied at both transmitter and receiver. We also analyze the impact of the relay on cooperation, as the relay node operates only if necessary, most of the reconfigurability charge ends up at the relay, whereas the PA and LNA operating modes tend to be reasonably fixed at the source and destination nodes. Finally, results show that the number of relays contributes to achieving long distance transmissions. Keywords: Energy Efficiency, Reconfigurable RF Transceivers, Spatial Diversity, Multiple Antennas, Cooperative Communications

    Bridging Causal Reversibility and Time Reversibility: A Stochastic Process Algebraic Approach

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    Causal reversibility blends reversibility and causality for concurrent systems. It indicates that an action can be undone provided that all of its consequences have been undone already, thus making it possible to bring the system back to a past consistent state. Time reversibility is instead considered in the field of stochastic processes, mostly for efficient analysis purposes. A performance model based on a continuous-time Markov chain is time reversible if its stochastic behavior remains the same when the direction of time is reversed. We bridge these two theories of reversibility by showing the conditions under which causal reversibility and time reversibility are both ensured by construction. This is done in the setting of a stochastic process calculus, which is then equipped with a variant of stochastic bisimilarity accounting for both forward and backward directions

    Distributed Antenna Selection for Massive MIMO Using Reversing Petri Nets

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