Studies in Software-Defined Radio System Implementation

Over the past decade, software-defined radios (SDRs) have an increasingly prevalent aspect of wireless communication systems. Different than traditional hardware radios which implement radio protocols using static electrical circuit, SDRs implement significant aspects of physical radio protocol using software programs running on a host processor. Because they use software to implement most of the radio functionality, SDRs are much more easily modified, edited, and upgraded than their hardware-defined counterparts. Consequently, researchers and developers have been developing previously hardware-defined radio systems within software. Thus, communication standards can be tested under different conditions or swapped out entirely by simply changing some code. Additionally, developers hope to implement more advanced functionality with SDRs such as cognitive radios that can sense the conditions of the environment and change parameters or protocol accordingly. This paper will outline the major aspects of SDRs including their explanation, advantages, and architecture. As SDRs have become more commonplace, many companies and organizations have developed hardware front-ends and software packages to help develop software radios. The most prominent hardware front-ends to date have been the USRP hardware boards. Additionally, many software packages exist for SDR development, including the open source GNU Radio and OSSIE and the closed source Simulink and Labview SDR packages. Using these development tools, researchers have developed many of the most relevant radio standards. This paper will explain the major hardware and software development tools for creating SDRs, and it will explain some of the most important SDR projects that have been implemented to date

Robust and Reliable Modulation Classification for MIMO Systems

Abstract: This paper develops a feature-based Automatic Modulation Classification (AMC) algorithm for spatially multiplexed Multiple-Input Multiple-Output (MIMO) systems. The proposed algorithm employs two Higher Order Cumulants (HOCs) of the estimated transmit signal streams as discriminating features, and a multiclass Support Vector Machine (SVM) as a classification system. A multi-classifier classification system is introduced to improve the robustness of the decision made by the classifier at each estimated transmit signal stream. Furthermore, an optimal decision fusion scheme using a Maximum-Likelihood (ML) criterion is also introduced to improve the accuracy and reliability of the final classification decision made in the fusion center. The proposed algorithm shows good performance under different operating conditions, over an acceptable range of SNR, without any prior information about the channel state

Application of radio environment maps for dynamic broadband access in TV bands in urban areas

Spectrum sharing based on the dedicated databases, particularly in the context of TV band, is widely considered as a promising tool for better spectrum utilization in the future wireless networks. Practical realization of this paradigm entails the need for the true protection of the incumbent system, and at the same time the guarantee of the quality of the services offered to the secondary users. In this respect, this papers discusses the results achieved in numerous measurement campaigns performed for last years in two European cities, i.e., Poznan, Poland and Barcelona, Spain. Both indoor and outdoor measurements of the TV band have been compared with the main purpose of true identification of key practical considerations for spectrum sharing in the TV white spaces. As such the paper constitutes a concise summary of various analyzes and provides pragmatic guidelines for deployment of radio-environment maps (REM) based systems. Based on the conducted measurements and achieved results, the set of practical conclusions for REMs has been deduced, and the prospective procedure of deployment of such a network has been proposed.Peer ReviewedPostprint (published version

Just In Time Assembly (JITA) - A Run Time Interpretation Approach for Achieving Productivity of Creating Custom Accelerators in FPGAs

The reconfigurable computing community has yet to be successful in allowing programmers to access FPGAs through traditional software development flows. Existing barriers that prevent programmers from using FPGAs include: 1) knowledge of hardware programming models, 2) the need to work within the vendor specific CAD tools and hardware synthesis. This thesis presents a series of published papers that explore different aspects of a new approach being developed to remove the barriers and enable programmers to compile accelerators on next generation reconfigurable manycore architectures. The approach is entitled Just In Time Assembly (JITA) of hardware accelerators. The approach has been defined to allow hardware accelerators to be built and run through software compilation and run time interpretation outside of CAD tools and without requiring each new accelerator to be synthesized. The approach advocates the use of libraries of pre-synthesized components that can be referenced through symbolic links in a similar fashion to dynamically linked software libraries. Synthesis still must occur but is moved out of the application programmers software flow and into the initial coding process that occurs when programming patterns that define a Domain Specific Language (DSL) are first coded. Programmers see no difference between creating software or hardware functionality when using the DSL. A new run time interpreter is introduced to assemble the individual pre-synthesized hardware accelerators that comprise the accelerator functionality within a configurable tile array of partially reconfigurable slots at run time. Quantitative results are presented that compares utilization, performance, and productivity of the approach to what would be achieved by full custom accelerators created through traditional CAD flows using hardware programming models and passing through synthesis

Misturador CMOS de 2,4GHz para conversão a baixas frequências operando em inversão moderada

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Elétrica, Florianópolis, 2009O objetivo deste trabalho é desenvolver um misturador ativo para conversão de um sinal de RF de 2,4GHz em um sinal de frequência intermediária 750kHz. A topologia escolhida foi a do misturador ativo de balanceamento simples uma vez que apresenta uma arquitetura simples, alto ganho de conversão e um bom isolamento entre as portas. A tecnologia CMOS utilizada foi o AMS 0,35?m que apresenta dispositivos de RF bem caracterizados e bem documentados e também oferece uma prototipagem de baixo custo. O estágio de entrada opera com o nível de inversão moderado e o transistor com uma fT de 16GHz. O misturador simulado apresenta impedância de saída de 403W, ganho de 11dB, figura de ruído em 16,3dB, ponto de compressão de 1dB em -8,76dBm e consumo de potência de 7,3mW

Estudio de estrategias distribuidas de reparto de recursos en redes inalámbricas cognitivas mediante teoría de juegos

Este proyecto se enmarca dentro del estudio de técnicas eficientes de reconfiguración y adaptación al entorno en un contexto de redes inalámbricas multisalto distribuidas. El proyecto propone técnicas distribuidas de reparto de recursos evaluadas mediante teoría de juegos. La teoría de juegos es una herramienta matemática que analiza las interacciones estratégicas entre múltiples agentes que toman decisiones. Por ello, resulta adecuada para analizar las prestaciones de este tipo de redes, donde cada nodo debe decidir sus parámetros de configuración de manera competitiva. Sin embargo, la complejidad matemática de los problemas a resolver resulta difícil de abordar computacionalmente. Por ello, una aproximación alternativa es el desarrollo de simuladores que modelan las interacciones entre los individuos, partiendo de diversas condiciones iniciales, que permiten evaluar las soluciones propuestas al problema planteado. En este proyecto se ha modificado un simulador ya existente sobre el que se han implementado las distintas estrategias distribuidas de reparto de recursos. Cada alternativa propuesta pretendía mejorar a las anteriores introduciendo un mayor grado de realismo en las simulaciones. Como conclusión, se ha comprobado la capacidad de la teoría de juegos para modelar mecanismos de gestión de recursos radio en redes cognitivas y se han diseñado propuestas distribuidas locales (necesitan poca información de señalización) con buenas prestaciones, comparadas con una solución que garantiza la convergencia y la proximidad al máximo (juego potencial). Por último, se ha demostrado que la incorporación de aprendizaje “no-regret” permite hacer frente a situaciones de no convergencia demostrando la potencialidad de las soluciones propuestas para adaptarse a escenarios variantes. Todo esto permite establecer el punto de partida para desarrollar en el futuro algoritmos distribuidos de gestión de recursos radio y su implementación en protocolos en redes mesh cognitivas