José Roberto Amazonas

The choice of the best among the shortest routes in transparent optical networks

This work introduces the problem of the best choice among M combinations of the shortest paths for dynamic provisioning of lightpaths in all-optical networks. To solve this problem in an optimized way (shortest path and load balance), a new fixed routing algorithm, named Best among the Shortest Routes (BSR), is proposed. The BSRs performance is compared in terms of blocking probability and network utilization with Dijkstras shortest path algorithm and others algorithms proposed in the literature. The evaluated scenarios include several representative topologies for all-optical networking and different wavelength conversion architectures. For all studied scenarios, BSR achieved superior performance.

An Outlier Detect Algorithm using Big Data Processing and Internet of Things Architecture

Abstract Data management in the Internet of Things is a crucial aspect. Considering a world of interconnected objects which constantly exchange many kinds of information, the volume of generated data and involved processes, implies that data management becomes critical. The aim of this paper is to propose an outlier detection procedure using the K-means algorithm and Big Data processing using the Hadoop platform and Mahout implementation integrated with our chosen Internet of Things architecture.

A critical review of OpenFlow/SDN-based networks

The separation of the data and control planes simplify the implementation of SDN applications. The centralised architecture of a controller based on the OpenFlow protocol is appealing to the network operators. We have reviewed the concept of SDNs and its extension to optical networks, and constrained and unconstrained wireless access networks. The current status of the proposed and implemented SDN architectures is such that the fulfilment of a SLA is an open issue. This aspect is left to be tackled by the SDN applications and the proposed architectures do not provide means to describe the interplay between different technology domains. In this paper we make an in depth analysis of the current proposed architectures and identify important challenges to be addressed by a novel integrated SDN architecture.

Energy-efficiency maximisation for cooperative and non-cooperative OFDMA cellular networks-a survey

In this survey, techniques to enhance energy efficiency EE in orthogonal frequency division multiple access OFDMA and orthogonal frequency division multiplexing OFDM systems, with or without the utilisation of the cooperative network paradigm, considering also the features provided in the standards of modern cellular wireless networks, such as LTE-Advanced and WiMAX, are discussed. For the non-cooperative EE maximisation case, we summarise resource allocation problems and also describe some techniques that can be combined with the basic power/subcarrier allocation problems. When considering the cooperative OFDMA case, we first discuss four basic variables that arise with the relay station implantation, and after that, other features are also listed, which can be combined with the previously discussed issues. Finally, we review some of the standardisation documents available for fourth-generation systems in order to obtain system parameters and simulation scenarios, discuss some methods to analyse and solve the optimisation problems that can be proposed with the aforementioned techniques and then point out important open trends and research challenges in the EE maximisation problem considering OFDMA scenario. Copyright

State-space modeling of long-range dependent teletraffic

This paper develops a new state-space model for long-range dependent (LRD) teletraffic. A key advantage of the state-space approach is that forecasts can be performed on-line via the Kalman predictor. The new model is a finite-dimensional (i. e., truncated) state-space representation of the FARIMA (fractional autoregressive integrated moving average) process. Furthermore, we investigate, via simulations, the multistep ahead forecasts obtained from the new model and compare them with those achieved by fitting high-order autoregressive (AR) models.

Exploring concurrency in data path functional units BIST plan optimization: a study-case

This paper presents a procedure to optimize the parallel test plan of all functional units present in a data path. Our algorithm defines which registers will be transformed into test pattern generators (TPGs) and signature analyzers (SAs), minimizing a test cost function. Cellular automata (CAs) registers will be used both for TPG and SA. Very good results were obtained for the tested architectures. A comparison between the parallel test and a serial test has shown a large test time reduction with a small hardware penalty. This procedure is part of an ongoing research which consists of the development of tools to automatically generate BIST testable circuits for architectures synthesized by the MACH high-level synthesis system.

TCNet: Trellis Coded Network — Implementation of QoS-aware routing protocols in WSNs

Wireless Sensor Networks (WSNs) are important infrastructures of the Internet of Things (IoT) architecture. Their huge potential to connect the real or physical world with the virtual world established new challenges of integration between “Infrastructure Networks” and “Wireless Domain” by means of protocols architectures compatible with the IP structure widely used in the Internet. WSNs are networks that may have a huge quantity of nodes where collaborative characteristics are exploited using ad hoc defined links. In addition, it is important to take into account that WSN nodes have few resources in terms of energy, processing power and memory. In this case, it is advantageous to employ self configurable architectures in which the competition to access channels and error control could be network distributed. Considering WSNs as an important structure for the IoT architecture, the interest in using sensor networks in the same universe as IP networks suggests the use of transit network configurations. This work proposes to implement the new concept of a “Trellis Coded Network”-(TCNet). This model uses Mealy machine-(MM) or low complexity Finite State Machine (FSM) network nodes (“XOR” gates and shift registers), eliminating the use of any routing tables by means of Trellis decoding. The sequence of states of the FSM thus corresponds to a network route to be traveled by a transmission frame. The route can be chosen based on criteria of Quality of Service (QoS)-aware routing protocols.

Quality of network economics optimisation using service level agreement modelling

This paper analyses the relationships between different service level agreement (SLA) components, that is, the different types of quality metrics employed by infrastructure and service providers. We propose that the quality of network economics (QoNE) be used to evaluate the quality of a network path for a given SLA model. Our evaluation indicates the usefulness of the QoNE metric, and it provides a new mechanism for the networking community to address network design problems when incorporating new challenges, such as the Internet of Things. We show how the proposed model can be implemented in software-defined network architecture applicable to networking technologies that include the interconnection of autonomous systems.

Generation of Gaussian Self-similar series via Wavelets for Use in Traffic Simulations

Measurements have shown that network traffic has fractal properties such as self-similarity and long memory or long-range dependence. Long memory is characterized by the existence of a pole at the origin of the power spectrum density function (1/f shape). It was also noticed that traffic may present short-range dependence at some time scales. The use of a “realistic” aggregated network traffic generator, one that synthesizes fractal time series, is fundamental to the validation of traffic control algorithms. In this article, the synthesis of approximate realizations of a kind of self-similar random process named fractional Gaussian noise is done via wavelet transform. The proposed method is also capable of synthesizing Gaussian time series with more generic spectra than 1/f, that is, time series that also have short-range dependence. The generation is done in two stages. The first one generates an approximate realization of fractional Gaussian noise via discrete Wavelet transform. The second one introduces short-range dependence through IIR (Infinite Impulse Response) filtering at the output of the first stage. A detailed characterization of the resulting series was done, using statistical moments of first, second, third and fourth orders, as well as specific statistical tests for self-similar series. It was verified that the Whittle estimator of the Hurst parameter is more robust than the periodogram method for series that simultaneously present short-range and long-range dependence.

Power and Subcarrier Allocation Strategies for Energy-Efficient Uplink OFDMA Systems

In this paper, we investigate computationally efficient strategies for energy-efficiency (EE) maximization in the uplink of a single-cell orthogonal frequency-division multiple-access system. We realize EE maximization by allocating power and subcarriers for each mobile station, and it has exponential complexity to achieve optimality. The Dinkelbach algorithm and Lagrange dual decomposition are well-established frameworks to solve the EE-maximization problem, but the definition of initial values and parameters remains an unresolved issue that is generally solved by empirical methods. To do this, we develop suitable procedures to efficiently calculate such values. We show that these procedures provide a very high EE, such that they can be systematized in two sub-optimal algorithms to efficiently allocate power and subcarriers without reliance on parameter-optimization problems.