Arismar Cerqueira Sodré

Implementation of an Optical-Wireless Network with Spectrum Sensing and Dynamic Resource Allocation Using Optically Controlled Reconfigurable Antennas

This work proposes the concept and reports the implementation of an adaptive and cognitive radio over fiber architecture. It is aimed at dealing with the new demands for convergent networks by means of simultaneously providing the functionalities of multiband radiofrequency spectrum sensing, dynamic resource allocation, and centralized processing capability, as well as the use of optically controlled reconfigurable antennas and radio over fiber technology. The performance of this novel and innovative architecture has been evaluated in a geographically distributed optical-wireless network under real conditions and for different fiber lengths. Experimental results demonstrate reach extension of more than 40 times and an enhancement of more than 30 dB in the carrier to interference plus noise ratio parameter.

Optically Controlled Reconfigurable Filtenna

This work is regarding the development of a novel antenna called optically controlled reconfigurable filtenna, which is based on the integration of a broadband printed antenna with a bandpass reconfigurable RF filter. The filter is designed by applying defected microstrip structure (DMS) technique and positioned in printed antenna feeding line in order to keep the same size of the original antenna. The filtenna bandwidth is optically reconfigurable by using two photoconductive silicon switches excited by CW laser at 808 nm. Numerical results rely on independent and switchable operational modes through the 2.4 and 5.1 GHz ISM bands, whereas measurements demonstrate two reconfigurable modes based on single-band/dual-band operation over the same frequency bands. The proposed device is validated by theoretical, numerical, and experimental results.

Waveguide-Based Antenna Arrays for 5G Networks

This work reports the development of two high-performance waveguide-based antenna arrays for 5G cellular networks, operating in the underutilized millimetre wave (mm-wave) frequency spectrum. Two different scenarios of mm-wave communications are proposed for illustrating the applicability of the proposed arrays, which provide specific radiation patterns, namely, 12 dBi gain omnidirectional coverage in the 28 GHz band and dual-band sectorial coverage using the 28 and 38 GHz bands with gain up to 15.6 dBi. Numerical and experimental results of the array reflection coefficient, radiation pattern, and gain have been shown in an excellent agreement.

Integrated multi-frequency lidar / radar system for precise and robust Doppler measurements

A novel architecture of an integrated photonic assisted radar-lidar system based on a single mode-locked laser is proposed and demonstrated. The lidar exploits a multi-frequency optical signal with tunable tones separation allowing a dynamic tradeoff among robustness and sensitivity of measurements. The radar, which employs the mode-locked laser for generating and receiving the radio-frequency signal operates in the X-band and simultaneously with the lidar. Velocity measurements for different tones separation are successfully demonstrated with good agreement between lidar and radar.

Service-oriented, name-based, and software-defined spectrum sensing and dynamic resource allocation for Wi-Fi networks using NovaGenesis

Computing power is increasingly enabling software-based networking. Successful technologies, like Wi-Fi, can now take advantage of the state of the art approaches for software-based architectures, such as software-defined, service-centric, and information-centric networking. In this paper, we employ NovaGenesis - a future Internet architecture - as the foundation for Wi-Fi networks spectrum sensing and dynamic resource allocation as a service. We propose a new paradigm called service-defined architecture (SDA), where NovaGenesis services self-organize towards Wi-Fi networks control and management. We proof this concept experimentally by means of a NovaGenesis named-services chain with named content exchanging.

NovaGenesis Applied to Information-Centric, Service-Defined, Trustable IoT/WSAN Control Plane and Spectrum Management

We integrate, for the first time in the literature, the following ingredients to deal with emerging dynamic spectrum management (DSM) problem in heterogeneous wireless sensors and actuators networks (WSANs), Internet of things (IoT) and Wi-Fi: (i) named-based routing to provide provenance and location-independent access to control plane; (ii) temporary storage of control data for efficient and cohesive control dissemination, as well as asynchronous communication between software-controllers and devices; (iii) contract-based control to improve trust-ability of actions; (iv) service-defined configuration of wireless devices, approximating their configurations to real services needs. The work is implemented using NovaGenesis architecture and a proof-of-concept is evaluated in a real scenario, demonstrating our approach to automate radio frequency channel optimization in Wi-Fi and IEEE 802.15.4 networks in the 2.4 GHz bands. An integrated cognitive radio system provides the dual-mode best channel indications for novel DSM services in NovaGenesis. By reconfiguring Wi-Fi/IoT devices to best channels, the proposed solution more than doubles the network throughput, when compared to the case of mutual interference. Therefore, environments equipped with the proposal provide enhanced performance to their users.

Elastipipe: On Providing Cloud Elasticity for Pipeline-structured Applications

Although offering clear benefits for Web and business-critical demands, the use of cloud elasticity still imposes challenges when trying to reap its benefits over complex applications such as those modeled as pipelines. This often happens because replication, the standard technique for resource reorganization, by default, doesn’t address both function-level parallelism and communication between working VMs. Taking into account this background, here we are proposing a model named Elastipipe to provide automatic elasticity over pipelines-structured applications. Our main goal is to reduce total execution time for a set of tasks in a way that is effortless to cloud users, eliminating the need for any preconfiguration. Elastipipe’s contribution consists in a framework designed to provide a new concept named flexible superscalar pipelines, in which scaling operations and load balancing take place over different elasticity units. An elasticity unit refers to a set of one or more stages of a pipeline that will be grouped together under the same elasticity rules. Using a real workload from an IT Brazilian company, the Elastipipe prototype presented performance gains of up to 60% when confronted with a non-elastic approach. In addition, we demonstrated that the functional decomposition of pipeline stages (CPU-bound, memory-bound, and so on) in corresponding elasticity units was responsible for the best results in terms of performance and cost.

Photonics-based tunable and broadband radio frequency converter

Abstract. This paper is regarding the concept and development of a photonics-based tunable and broadband radio frequency converter (PBRC). It employs an external modulation technique to generate and reconfigure its output frequency, a digital circuit to manage the modulators’ bias voltages, and an optical interface for connecting it to optical-wireless networks based on radio-over-fiber technology. The proposed optoelectronic device performs photonics-based upconversion and downconversion as a function of the local oscillator frequency and modulators’ bias points. Experimental results demonstrate a radiofrequency (RF) carrier conversion with spectral purity over the frequency range from 750 MHz to 6.0 GHz, as well as the integration of the photonics-based converter with an optical backhaul based on a 1.5-km single-mode fiber from a geographically distributed optical network. Low phase noise and distortion absence illustrate its applicability for convergent and reconfigurable optical wireless communications. A potential application relies on the use of PBRC in convergent optical wireless networks to dynamically provide RF carriers as a function of the telecom operator demand and radio propagation environment.

Implementation of a photonics-based frequency reconfigurable optical-wireless network

This work reports the implementation of a frequency reconfigurable optical-wireless network based on a photonics technology. An optical modulator is used to dynamically manage and manipulate RF signals over different frequency bands by means of optical frequency multiplication. The proposed concept of a convergent and frequency reconfigurable architecture has been successfully demonstrated by applying radio over fiber technology in a geographically-distributed optical-wireless network. Experimental results of RF generation up to 10.4 GHz are presented, including high spectral purity RF carriers at 2.6 and 5.2 GHz with low phase noise and distortion absence.