This Master's thesis deals with proposal of Flexible Spectrum Usage (FSU) algorithm based on policy agreed among operators. The introduction presents basic information about properties of next generation mobile communication ITM-Advanced system. After the introductory part the attention is given to the items efficient for FSU implementation as well as parameters used for evaluation of FSU algorithm efficiency. Several variants policy based FSU algorithm utilize value of Signal to Interference plus Noise Ratio (SINR) is designed. The SINR information is used to combat with mutual interference which is caused by coexistence of several operators in the same geographical area sharing over the same spectrum pool. Individual needed as traffic and quality of service requirements of each operator is taken into consideration as well. The main aim is to maximize cell troughput as well as data- rates for each user of HBS. For simulation of proposal algorithm is considered deployment of four Currently Home Base Stations (HBS) in indoor loacal area scenerio with random number of users in given range. Each operator makes independent dicision without signalling exchange among other. The only considered information that HBS can use is gotten by scenning its environment. This problem soliving is considered to use Cognitive Radio (CR)

This Master's thesis deals with proposal of Flexible Spectrum Usage (FSU) algorithm based on policy agreed among operators. The introduction presents basic information about properties of next generation mobile communication ITM-Advanced system. After the introductory part the attention is given to the items efficient for FSU implementation as well as parameters used for evaluation of FSU algorithm efficiency. Several variants policy based FSU algorithm utilize value of Signal to Interference plus Noise Ratio (SINR) is designed. The SINR information is used to combat with mutual interference which is caused by coexistence of several operators in the same geographical area sharing over the same spectrum pool. Individual needed as traffic and quality of service requirements of each operator is taken into consideration as well. The main aim is to maximize cell troughput as well as data- rates for each user of HBS. For simulation of proposal algorithm is considered deployment of four Currently Home Base Stations (HBS) in indoor loacal area scenerio with random number of users in given range. Each operator makes independent dicision without signalling exchange among other. The only considered information that HBS can use is gotten by scenning its environment. This problem soliving is considered to use Cognitive Radio (CR)

Radio spectrum is a vital national asset; proper management of this finite resource is essential to the operation and development of telecommunications, radio-navigation, radio astronomy, and passive remote sensing services. To maximize the utility of the radio spectrum, knowledge of its current usage is beneficial. As a result, several spectrum studies have been conducted in urban Atlanta, suburban Atlanta, and rural North Carolina. These studies improve upon past spectrum studies by resolving spectrum usage by nearly all its possible parameters: frequency, time, polarization, azimuth, and location type. The continuous frequency range from 400MHz to 7.2 GHz was measured with a custom-designed system. More than 8 billion spectrum measurements were taken over several months of observation. A multi-parameter spectrum usage detection method was developed and analyzed with data from the spectrum studies. This method was designed to exploit all the characteristics of spectral information that was available from the spectrum studies. Analysis of the spectrum studies showed significant levels of underuse. The level of spectrum usage in time and azimuthal space was determined to be only 6.5 % for the urban Atlanta, 5.3 % for suburban Atlanta, and 0.8 % for the rural North Carolina spectrum studies. Most of the frequencies measured never experienced usage. Interference was detected in several protected radio astronomy and sensitive radio navigation bands. A cognitive radio network architecture to share spectrum with fixed microwave systems was developed. The architecture uses a broker-based sharing method to control spectrum access and investigate interference issues.

The rapid increasing interest in wireless communication has led to the continuous development of wireless devices and technologies. The modern convergence and interoperability of wireless technologies has further increased the amount of services that can be provided, leading to the substantial demand for access to the radio frequency spectrum in an efficient manner. Cognitive radio (CR) an innovative concept of reusing licensed spectrum in an opportunistic manner promises to overcome the evident spectrum underutilization caused by the inflexible spectrum allocation. Spectrum sensing in an unswerving and proficient manner is essential to CR. Cooperation amongst spectrum sensing devices are vital when CR systems are experiencing deep shadowing and in a fading environment. In this thesis, cooperative spectrum sensing (CSS) schemes have been designed to optimize detection performance in an efficient and implementable manner taking into consideration: diversity performance, detection accuracy, low complexity, and reporting channel bandwidth reduction. The thesis first investigates state of the art spectrums sensing algorithms in CR. Comparative analysis and simulation results highlights the different pros, cons and performance criteria of a practical CSS scheme leading to the problem formulation of the thesis. Motivated by the problem of diversity performance in a CR network, the thesis then focuses on designing a novel relay based CSS architecture for CR. A major cooperative transmission protocol with low complexity and overhead - Amplify and Forward (AF) cooperative protocol and an improved double energy detection scheme in a single relay and multiple cognitive relay networks are designed. Simulation results demonstrated that the developed algorithm is capable of reducing the error of missed detection and improving detection probability of a primary user (PU). To improve spectrum sensing reliability while increasing agility, a CSS scheme based on evidence theory is next considered in this thesis. This focuses on a data fusion combination rule. The combination of conflicting evidences from secondary users (SUs) with the classical Dempster Shafter (DS) theory rule may produce counter-intuitive results when combining SUs sensing data leading to poor CSS performance. In order to overcome and minimise the effect of the counter-intuitive results, and to enhance performance of the CSS system, a novel state of the art evidence based decision fusion scheme is developed. The proposed approach is based on the credibility of evidence and a dissociability degree measure of the SUs sensing data evidence. Simulation results illustrate the proposed scheme improves detection performance and reduces error probability when compared to other related evidence based schemes under robust practcial scenarios. Finally, motivated by the need for a low complexity and minmum bandwidth reporting channels which can be significant in high data rate applications, novel CSS quantization schemes are proposed. Quantization methods are considered for a maximum likelihood estimation (MLE) and an evidence based CSS scheme. For the MLE based CSS, a novel uniform and optimal output entropy quantization scheme is proposed to provide fewer overhead complexities and improved throughput. While for the Evidence based CSS scheme, a scheme that quantizes the basic probability Assignment (BPA) data at each SU before being sent to the FC is designed. The proposed scheme takes into consideration the characteristics of the hypothesis distribution under diverse signal-to-noise ratio (SNR) of the PU signal based on the optimal output entropy. Simulation results demonstrate that the proposed quantization CSS scheme improves sensing performance with minimum number of quantized bits when compared to other related approaches.

The aim of this master thesis is description of creating application designated to improve orienta-tion in radio spectrum usage in the Czech Republic and publication of data used by application as open data. First, the thesis describes open data, its importance and method of working with it. This part is followed by an analysis of issues, analysis of available data and selection of methodology for appli-cation development as well as for open data publication. Description of the process of application development and its launch follows. Whole thesis concludes description of the process for open data publication.

In this thesis we investigate how to improve the performance of MU-MIMO wireless system in terms of achieving Shannon capacity limit and efficient use of precious resource of radio spectrum in wireless communication. First a new suboptimal volume-based scheduling algorithm is presented, which can be applied in MU-MIMO downlink system to transmit signals concurrently to multiple users under the assumption of perfect channel information at transmitter and receiver. The volume-based scheduling algorithm utilises Block Diagonalisation precoding and Householder reduction procedure of QR factorisation. In comparison with capacity-based suboptimal scheduling algorithm, the volume-based algorithm has much reduced computational complexity with only a fraction of sum-rate capacity penalty from the upper bound of system capacity limit. In comparison with semi-orthogonal user selection suboptimal scheduling algorithm, the volume-based scheduling algorithm can be implemented with less computational complexity. Furthermore, the sum-rate capacity achieved via volume-based scheduling algorithm is higher than that achieved by SUS scheduling algorithm in the MIMO case. Then, a two-step scheduling algorithm is proposed, which can be used in the MU-MIMO system and under the assumption that channel state information is known to the receiver, but it is not known to the transmitter and the system under the feedback resource constraint. Assume that low bits codebook and high bits codebook are stored at the transmitter and receiver. The users are selected by using the low bits codebook; subsequently the BD precoding vectors for selected users are designed by employing high bits codebook. The first step of the algorithm can alleviate the load on feedback uplink channel in the MU-MIMO wireless system while the second step can aid precoding design to improve system sum-rate capacity. Next, a MU-MIMO cognitive radio (CR) wireless system has been studied. In such system, a primary wireless network and secondary wireless network coexist and the transmitters and receivers are equipped with multiple antennas. Spectrum sensing methods by which a portion of spectrum can be utilised by a secondary user when the spectrum is detected not in use by a primary user were investigated. A Free Probability Theory (FPT) spectrum sensing method that is a blind spectrum sensing method is proposed. By utilizing the asymptotic behaviour of random matrix based on FPT, the covariance matrix of transmitted signals can be estimated through a large number of observations of the received signals. The method performs better than traditional energy spectrum sensing method. We also consider cooperative spectrum sensing by using the FPT method in MU-MIMO CR system. Cooperative spectrum sensing can improve the performance of signal detection. Furthermore, with the selective cooperative spectrum sensing approach, high probability of detection can be achieved when the system is under false alarm constraint. Finally, spectrum sensing method based on the bispectrum of high-order statistics (HOS) and receive diversity in SIMO CR system is proposed. Multiple antennas on the receiver can improve received SNR value and therefore enhance spectrum sensing performance in terms of increase of system-level probability of detection. Discussions on cooperative spectrum sensing by using the spectrum sensing method based on HOS and receive diversity are presented.

The continuing increase in the adoption and use of wireless technology aggravates the problem of spectrum scarcity due to the way we utilize the spectrum. The radio spectrum is a limited resource regulated by governmental agencies according to a fixed spectrum assignment policy. However, many studies show that this fixed radio frequency allocation leads to significant underutilization of the radio spectrum creating artificial scarcity, as most of the allocated spectrum is not used all of the time in every location. To meet services growing demands, efficient use of the spectrum is essential. Therefore, there is a need to estimate the radio spectrum utilization in several locations and during different periods of time in order to opportunistically exploit the existing wireless spectrum. Cognitive radio technology aims to search for those portions of the radio spectrum that are assigned to a specific service, but are unused during a specific time and at specific location in order to share these white spaces and thus to reduce the radio spectrum inefficiency. In this thesis, we study spectrum utilization in the frequency range from 790MHz to 925MHz. The spectrum sensing has been realized using a number of specialized microcontroller based white space sensors which utilize energy detection, situated in different locations of a building in Kista, Sweden. The occupancy of the frequency bands in this chunk of the spectrum is quantified as the fraction of samples with a power level greater than a threshold. The results from these spectrum measurements show that a significant amount of spectrum in this scanned range around the building is inefficiently used all the time. / Den senaste tidens ökning av trådlös teknik förvärrar problemet med spektrumbrist på grund av hur vi använder den. Det radiospektrum är en begränsad resurs som regleras av statliga myndigheter enligt en fast spektrumtilldelningen politik. Men många studier visar att den fasta frekvensplan leder till betydande underutnyttjande av radiospektrum och skapar en konstgjord brist eftersom de flesta av de tilldelade spektrumet inte används hela tiden i varje platsen. För att uppfylla tjänster ökade krav, är viktigt en effektiv användning av spektrumet. Därför finns det ett behov av att uppskatta användningen av radiospektrum i flera platser och i olika tidsperioder för att kunna utnyttja den befintliga trådlösa spektrumet i opportunistiskt sätt. Kognitiv radio teknologi syftar till att söka efter dessa delar av radiospektrum som tilldelas till en konkret tjänst och är oanvända i en viss tid och på viss plats för att dela dessa vita ytor och därför lösa radio spektrum ineffektivitet problem. I denna uppsats studerar vi spektrumanvändning i frekvensområdet från 790 MHz till 925 MHz. Spektrat avkänning har utförts med hjälp av ett antal specialiserade mikrokontroller blanktecken sensorer vilka utnyttjar energin upptäckt, som ligger på olika platser i en byggnad i Kista, Sverige. Uthyrningsgraden av frekvensbanden i denna del av spektrumet kvantifieras som antalet prover med en effektnivå överstiger en tröskel. Resultaten från spektrat mätningarna visar att en betydande del av spektrumet i denna scannade intervall ineffektivt används hela tiden.

[pt] A tecnologia de rádios cognitivos está surgindo como uma eficaz alternativa para aumentar o número de usuários de serviços de dados em banda larga em diversas faixas de frequências. O conceito pretende resolver a escassez do espectro a partir de duas características básicas: a capacidade cognitiva e a capacidade de reconfiguração. A capacidade cognitiva refere-se à habilidade do rádio de conhecer o meio no qual pretende operar, identificar de forma oportunista os espaços espectrais não utilizados na sua totalidade ou em alguns intervalos de tempo e, a partir da sua reconfiguração transmitir informação sem provocar interferência no usuário principal da porção do espectro utilizado. Esta dissertação de mestrado apresenta os resultados obtidos da análise do desempenho de regras de fusão para sensoriamento remoto cooperativo. Na primeira parte são abordados os fundamentos teóricos de Rádio cognitivo e os aspectos mais importantes do gerenciamento do espectro radioelétrico, além dos fundamentos do detector de energia, detector mais simples de implementar e utilizar para o sensoriamento em redes cognitivas. A seguir são abordadas diferentes técnicas para sensoriamento em redes cognitivas, apresentando os esquemas de decisão e a detecção convencional do espectro cooperativo, os métodos Hard decision e Soft decision. Finalmente uma avaliação das regras de sensoriamento cooperativo em cenários reais é realizada para obter as conclusões do trabalho. / [en] Cognitive radio technology is emerging as an effective alternative to increase the number of users in several frequency bands. The concept aims to solve the scarcity of the spectrum from two basic characteristics: the cognitive capacity and the capacity of reconfiguration. Cognitive ability refers to the ability of the radio to know the medium in which it is operating, to identify in an opportunistic way the unused spectral spaces in their totality or in some intervals of time and, from its reconfiguration transmit information without causing interference in the user of the portion of the spectrum used. This dissertation presents the results obtained from the analysis of the performance of fusion rules for cooperative remote sensing. The first part deals with the theoretical foundations of cognitive radio and the most important aspects of radioelectric spectrum management, as well as the fundamentals of the energy detector, the most important detector used in cognitive networks. Next, different techniques for sensing in cognitive networks are presented, presenting decision schemes and conventional detection of the cooperative spectrum, the Hard decision and Soft decision methods. Finally, an evaluation of the rules of cooperative sensing in real scenarios is carried out to obtain the conclusions of the work.

The Peruvian government has stablished mandatory payments that telecom companies have to make: the regulatory contribution, the tariff for radio spectrum and the fee for commercial exploitation.In this article, the authors examine what tax nature and what validity basis those impositions have. / El Estado peruano ha establecido pagos obligatorios que deben realizar las empresas operadoras de telecomunicaciones: el aporte por regulación pagado, el canon por el uso del espectro radioeléctrico y la tasa por explotación comercial. En el presente artículo, los autores examinan qué naturaleza tributaria y qué fundamento de validez tienen estas exacciones.

Made available in DSpace on 2014-12-17T14:56:19Z (GMT). No. of bitstreams: 1 ArthurDLL_DISSERT.pdf: 2517302 bytes, checksum: c3d693c770dc1c58bad5f378aba6d268 (MD5) Previous issue date: 2014-06-28 / The increasing demand for high performance wireless communication systems has shown the inefficiency of the current model of fixed allocation of the radio spectrum. In this context, cognitive radio appears as a more efficient alternative, by providing opportunistic spectrum access, with the maximum bandwidth possible. To ensure these requirements, it is necessary that the transmitter identify opportunities for transmission and the receiver recognizes the parameters defined for the communication signal. The techniques that use cyclostationary analysis can be applied to problems in either spectrum sensing and modulation classification, even in low signal-to-noise ratio (SNR) environments. However, despite the robustness, one of the main disadvantages of cyclostationarity is the high computational cost for calculating its functions. This work proposes efficient architectures for obtaining cyclostationary features to be employed in either spectrum sensing and automatic modulation classification (AMC). In the context of spectrum sensing, a parallelized algorithm for extracting cyclostationary features of communication signals is presented. The performance of this features extractor parallelization is evaluated by speedup and parallel eficiency metrics. The architecture for spectrum sensing is analyzed for several configuration of false alarm probability, SNR levels and observation time for BPSK and QPSK modulations. In the context of AMC, the reduced alpha-profile is proposed as as a cyclostationary signature calculated for a reduced cyclic frequencies set. This signature is validated by a modulation classification architecture based on pattern matching. The architecture for AMC is investigated for correct classification rates of AM, BPSK, QPSK, MSK and FSK modulations, considering several scenarios of observation length and SNR levels. The numerical results of performance obtained in this work show the eficiency of the proposed architectures / O aumento da demanda por sistemas de comunica??o sem fio de alto desempenho tem evidenciado a inefici?ncia do atual modelo de aloca??o fixa do espectro de r?dio. Nesse contexto, o r?dio cognitivo surge como uma alternativa mais eficiente, ao proporcionar o acesso oportunista ao espectro, com a maior largura de banda poss?vel. Para garantir esses requisitos, ? necess?rio que o transmissor identifique as oportunidades de transmiss?o e que o receptor reconhe?a os par?metros definidos para o sinal de comunica??o. As t?cnicas que utilizam a an?lise cicloestacion?ria podem ser aplicadas tanto em problemas de sensoriamento espectral, quanto na classifica??o de modula??es, mesmo em ambientes de baixa rela??o sinal-ru?do (SNR). Entretanto, apesar da robustez, uma das principais desvantagens da cicloestacionariedade est? no elevado custo computacional para o c?lculo das suas fun??es. Este trabalho prop?e arquiteturas eficientes de obten??o de caracter?sticas cicloestacion?rias para serem empregadas no sensoriamento espectral e na classifica??o autom?tica de modula??es (AMC). No contexto do sensoriamento espectral, um algoritmo paralelizado para extrair as caracter?sticas cicloestacion?rias de sinais de comunica??o ? apresentado. O desempenho da paraleliza??o desse extrator de caracter?sticas ? avaliado atrav?s das m?tricas de speedup e efici?ncia paralela. A arquitetura de sensoriamento espectral ? analisada para diversas configura??es de probabilidades de falso alarme, n?veis de SNR e tempo de observa??o das modula??es BPSK e QPSK. No contexto da AMC, o perfil-alfa reduzido ? proposto como uma assinatura cicloestacion?ria calculada para um conjunto reduzido de frequ?ncia c?clicas. Essa assinatura ? validada por meio de uma arquitetura de classifica??o baseada no casamento de padr?es. A arquitetura para AMC ? investigada para as taxas de acerto obtidas para as modula??es AM, BPSK, QPSK, MSK e FSK, considerando diversos cen?rios de tempo de observa??o e n?veis de SNR. Os resultados num?ricos de desempenho obtidos neste trabalho demonstram a efici?ncia das arquiteturas propostas