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Spectrum scarcity is an important challenge faced by high-speed wireless communications. Meanwhile, caused by current spectrum assignment policy, a large portion of spectrum is underutilized. Motivated by this, cognitive radio (CR) has emerged as one of the most promising candidate solutions to improve spectrum utilization, by allowing secondary users (SUs) to opportunistically access the temporarily unused spectrum, without introducing harmful interference to primary users. Moreover, opening of TV white space (TVWS) gives us the con dence to enable CR for TVWS spectrum. A crucial requirement in CR networks (CRNs) is wideband spectrum sensing, in which SUs should detect spectral opportunities across a wide frequency range. However, wideband spectrum sensing could lead to una ordably high sampling rates at energy-constrained SUs. Compressive sensing (CS) was developed to overcome this issue, which enables sub-Nyquist sampling by exploiting sparse property. As the spectrum utilization is low, spectral signals exhibit a natural sparsity in frequency domain, which motivates the promising application of CS in wideband CRNs. This thesis proposes several e ective algorithms for invoking CS in wideband CRNs. Speci cally, a robust compressive spectrum sensing algorithm is proposed for reducing computational complexity of signal recovery. Additionally, a low-complexity algorithm is designed, in which original signals are recovered with fewer measurements, as geolocation database is invoked to provide prior information. Moreover, security enhancement issue of CRNs is addressed by proposing a malicious user detection algorithm, in which data corrupted by malicious users are removed during the process of matrix completion (MC). One key spotlight feature of this thesis is that both real-world signals and simulated signals over TVWS are invoked for evaluating network performance. Besides invoking CS and MC to reduce energy consumption, each SU is supposed to harvest energy from radio frequency. The proposed algorithm is capable of o ering higher throughput by performing signal recovery at a remote fusion center.

Radio spectrum is becoming scarce resource due to increase in the usage of wireless communication devices. However studies have revealed that most of the allotted spectrum is not used effectively. Given the demand for more bandwidth and the amount of underutilized spectrum, DSA (Dynamic Spectrum Access) networks employing cognitive radios are a solution that can revolutionize the telecommunications industry, significantly changing the way we use spectrum resources, and design wireless systems and services. Cognitive radio has improve the spectral efficiency of licensed radio frequency bands by accessing unused part of the band opportunistically without interfering with a license primary user PU. In this thesis we investigate the effects on the quality of service (QoS) performance of spectrum management techniques for the connection-based channel usage behavior for Secondary user (SU). This study also consider other factors such as spectrum sensing time, spectrum handoff and generally distributed service time and channel contention for different SUs. The preemptive resume priority M/G/1 queuing theory is used to characterize the above mentioned effects. The proposed structure of the model can integrate various system parameters such spectrum sensing, spectrum decision, spectrum sharing and spectrum handoff. / Sajid Mahmood 0046-762788990 Mujeeb Abdullah 0046-760908069

This research analyzes Guatemala’s 1996 telecommunications reform, with an emphasis on how the introduction of private property rights in the electromagnetic spectrum has affected provision of, and access to, non-profit community radio, a critical media for the country’s indigenous Maya. The Guatemalan ‘experiment’ is the first applied test of Ronald Coase’s 1959 call for property rights in radio spectrum. To date, spectrum liberalization in most countries, including Canada, has upheld a model of resource stewardship in which the state retains ownership of the spectrum and a measure of control over frequency allocations. In Guatemala, by contrast, the state has ceded spectrum control to the private sector by auctioning off legal title to electromagnetic frequencies and allowing secondary markets in spectrum trading to develop. Formerly free under license to Guatemalan nationals only, FM frequencies sold with title under Guatemala’s revamped telecommunications law fetch as much as US$750,000 at auction. Broadcasting rights have disproportionately accrued to foreign nationals and commercial operators, while community broadcasters operating without title are accused of ‘stealing’ spectrum resources (causing interference on titled bandwidth), for which they face fines of between US$10,001 and $100,000 and up to six years in prison. Scholar-advocates and industry lobbyists credit Guatemala’s propertization regime with maximizing resource efficiency, institutionalizing justice, and offering rich and poor countries alike a practical model for spectrum reform. The Inter-American Commission on Human Rights and other critics, however, argue that the regime discriminates against those who lack the financial resources to purchase spectrum title and effectively bars non-profit community radio stations from legal access to the airwaves. This study traces the intellectual roots of (neo)liberal reform and examines parallels between geographies of inequality in Guatemala’s landscape and soundscape in order to demonstrate that the costs of enclosing and commodifying resources once held in common has consistently and disproportionately fallen on Guatemala’s indigenous population. / Thesis (Master, Geography) -- Queen's University, 2008-09-26 09:24:05.497

No / Abstract: The scarcity of frequency spectrum used for wireless communication systems has attracted a considerable amount of attention in recent years. The cognitive radio (CR) terminology has been widely accepted as a smart platform mainly aimed at the efficient interrogation and utilization of permitted spectrum. Non-parametric spectrum sensing, or estimation, represents one of the prominent tools that can be proposed when CR works under an undetermined environment. As such, the periodogram, filter bank, and multi-taper methods are well considered in many studies without relying on the transmission channel's characteristics. A unified approach to all these non-parametric spectrum sensing techniques is presented in this paper with analytical and performance comparison using simulation methods. Results show that the multi-taper method outperforms the others.

A methodology for the measurement of the radio frequency environment close to the radio noise floor is presented for urban, suburban and rural areas within New Zealand for the purposes of characterisation and trend monitoring by radio spectrum managers. Flux density measurements in bands within a range of frequencies from 80 MHz to 8 GHz have been made in urban, suburban and rural areas of New Zealand during 2007 and 2008. An analysis of the band occupancy is presented in summary form. These summaries are intended as a starting point for radio spectrum usage and can be used as a reference for any future measurements. A description of the computer directories and charts resulting from these measurements, using 20 MHz bandwidths have also been included. All the results for the work have been collated in a set of computer directories named “NZRFI Directories 2007 2008”, which are intended as a reference for use in the determination of local activity in particular frequency ranges. A disc with the full range measurement spectral density charts and channel occupancy charts accompanies this work. Also included on the disc are sets of 20 MHz band charts for some urban, suburban and rural location measurements.

A methodology for the measurement of the radio frequency environment close to the radio noise floor is presented for urban, suburban and rural areas within New Zealand for the purposes of characterisation and trend monitoring by radio spectrum managers. Flux density measurements in bands within a range of frequencies from 80 MHz to 8 GHz have been made in urban, suburban and rural areas of New Zealand during 2007 and 2008. An analysis of the band occupancy is presented in summary form. These summaries are intended as a starting point for radio spectrum usage and can be used as a reference for any future measurements. A description of the computer directories and charts resulting from these measurements, using 20 MHz bandwidths have also been included. All the results for the work have been collated in a set of computer directories named “NZRFI Directories 2007 2008”, which are intended as a reference for use in the determination of local activity in particular frequency ranges. A disc with the full range measurement spectral density charts and channel occupancy charts accompanies this work. Also included on the disc are sets of 20 MHz band charts for some urban, suburban and rural location measurements.

A methodology for the measurement of the radio frequency environment close to the radio noise floor is presented for urban, suburban and rural areas within New Zealand for the purposes of characterisation and trend monitoring by radio spectrum managers. Flux density measurements in bands within a range of frequencies from 80 MHz to 8 GHz have been made in urban, suburban and rural areas of New Zealand during 2007 and 2008. An analysis of the band occupancy is presented in summary form. These summaries are intended as a starting point for radio spectrum usage and can be used as a reference for any future measurements. A description of the computer directories and charts resulting from these measurements, using 20 MHz bandwidths have also been included. All the results for the work have been collated in a set of computer directories named “NZRFI Directories 2007 2008”, which are intended as a reference for use in the determination of local activity in particular frequency ranges. A disc with the full range measurement spectral density charts and channel occupancy charts accompanies this work. Also included on the disc are sets of 20 MHz band charts for some urban, suburban and rural location measurements.

This paper describes the regulation of radio spectrum transfer for public telecommunications services, as part of the secondary market for spectrum. The legal framework and administrative precedents issued by competent authorities are analyzed. / El presente trabajo describe la regulación de la transferencia de espectro radioeléctrico en el ámbito de los servicios públicos de telecomunicaciones, como parte del mercado secundario de espectro. Se analiza el marco legal y los precedentes administrativos que han emitido las autoridades encargadas de la materia.

What role does the media fulfill in the current stage of Latin American democracy? In all cases, is the possibility of regulating the media incompatiblewith the freedom of speech and enterprise of thepeople who own it?In this article, the renowned author shows his point of view regarding these questions, as well as offering a critique related to how the relationship between the media and democracy has been developing in our society. Lastly, he presents a proposal of media regulation in order to make democracy viable, but without   compromising constitutional freedoms. / ¿Cuál es el rol de los medios de comunicación en elestado actual de la democracia latinoamericana? En todos los casos, ¿la posibilidad de regular los medios de comunicación está reñida con la libertadde expresión y de empresa de sus dueños?En el presente artículo, el renombrado autor muestra su punto de vista con respecto a estas preguntas, y realiza una crítica con relación a cómo se ha venido desarrollando la relación entre los medios y la democracia en nuestra sociedad. Finalmente, plantea una propuesta de regulación de los medios, de cara a poder viabilizar la democracia, pero sin que queden en entredicho las libertades constitucionales.