Search

The traditional approach of dealing with spectrum management in wireless communications has been through the definition on a license user granted exclusive exploitation rights for a specific frequency.

This paper presents a sophisticated radio spectrum measurement platform specifically envisaged and designed for spectrum occupancy surveys in the context of Dynamic Spectrum Access/Cognitive Radio (DSA/CR). The presented tool is a very flexible computer-controlled radio measurement system, which has successfully been used in extensive spectrum measurement campaigns and empirical studies in the context of the DSA/CR technology. An exhaustive and in-depth description of the developed measurement platform is provided, with a special emphasis on implementation details and lessons learned during the development of the tool that may result helpful to other researchers and engineers in the development of similar radio spectrum measurement tools.

The development of the cognitive radio technology can enormously benefit from the availability of realistic and accurate spectrum occupancy models. Time-dimension models of spectrum use proposed in the literature so far are able to capture and reproduce essential temporal characteristics such as the mean occupancy level (duty cycle) and the statistical distribution of busy/idle-period lengths. However, more sophisticated aspects of spectrum use, such as time-correlation properties, have not been properly addressed yet. In this context, this paper studies and analyzes, based on field measurements of various radio technologies, the time-correlation properties of spectrum use. Appropriate models and simulation techniques are proposed in order to accurately capture and reproduce such features.

Premi extraordinari doctorat curs 2010-2011, àmbit d’Enginyeria de les TIC The owned spectrum allocation policy, in use since the early days of modern radio communications, has been proven to effectively control interference among radio communication systems. However, the overwhelming proliferation of new operators, innovative services and wireless technologies during the last years has resulted, under this static regulatory regime, in the depletion of spectrum bands with commercially attractive radio propagation characteristics. An important number of spectrum measurements, however, have shown that spectrum is mostly underutilized, thus indicating that the virtual spectrum scarcity problem actually results from static and inflexible spectrum management policies rather than the physical scarcity of radio resources. This situation has motivated the emergence of Dynamic Spectrum Access (DSA) methods based on the Cognitive Radio (CR) paradigm, which has gained popularity as a promising solution to conciliate the existing conflicts between spectrum demand growth and spectrum underutilization. The basic underlying idea of DSA/CR is to allow unlicensed (secondary) users to access in an opportunistic and non-interfering manner some licensed bands temporarily unoccupied by the licensed (primary) users. Due to the opportunistic nature of this principle, the behavior and performance of a DSA/CR network depends on the spectrum occupancy patterns of the primary system. A realistic and accurate modeling of such patterns becomes therefore essential and extremely useful in the domain of DSA/CR research. The potential applicability of spectrum usage models ranges from analytical studies to the design and dimensioning of secondary networks as well as the development of innovative simulation tools and more efficient DSA/CR techniques. Spectrum occupancy modeling in the context of DSA/CR constitutes a rather unexplored research area. This dissertation addresses the problem of modeling spectrum usage in the context of DSA/CR by contributing a comprehensive and holistic set of realistic models capable to accurately capture and reproduce the statistical properties of spectrum usage in real radio communication systems in the time, frequency and space dimensions. The first part of this dissertation addresses the development of a unified methodological framework for spectrum measurements in the context of DSA/CR and presents the results of an extensive spectrum measurement campaign performed over a wide variety of locations and scenarios in the metropolitan area of Barcelona, Spain, to identify potential bands of interest for future DSA/CR deployments. To the best of the author's knowledge, this is the first study of these characteristics performed under the scope of the Spanish spectrum regulation and one of the earliest studies in Europe. The second part deals with various specific aspects related to the processing of measurements to extract spectrum occupancy patterns, which is largely similar to the problem of spectrum sensing in DSA/CR. The performance of energy detection, the most widely employed spectrum sensing technique in DSA/CR, is first assessed empirically. The outcome of this study motivates the development of a more accurate theoretical-empirical performance model as well as an improved energy detection scheme capable to outperform the conventional method while preserving a similar level of complexity, computational cost and application. The findings of these studies are finally applied in the third part of the dissertation to the development of innovative spectrum usage models for the time (in discrete- and continuous-time versions), frequency and space domains. The proposed models can been combined and integrated into a unified modeling approach where the time, frequency and space dimensions of spectrum usage can simultaneously be reproduced, thus providing a complete and holistic characterization of spectrum usage in real systems for the analysis, design and simulation of the future DSA/CR networks. Award-winning

Deliverable D4.1 del projecte Europeu FARAMIR (248351) We describe herein the envisioned improvements of the REMs due to advanced sensing and processing. In relation to that, we also discuss the underlying modelling assumptions. Finally, we comment on how REMs can be of use in different scenarios as established in WP2.

Deliverable del projecte europeu NEWCOM++ This deliverable provides the final report with the summary of the activities carried out in NEWCOM++ WPR9, with a particular focus on those obtained during the last year. They address on the one hand RRM and JRRM strategies in heterogeneous scenarios and, on the other hand, spectrum management and opportunistic spectrum access to achieve an efficient spectrum usage. Main outcomes of the workpackage as well as integration indicators are also summarised.

This deliverable (DR9.2) describes the radio resource management, joint radio resource management and advanced spectrum management strategies developed in each of the tasks of WPR.9 during the second year of study. The proposed algorithms together with the results of evaluation in scenarios identified in the deliverable DR9.1 are presented. A special attention is given to JRRM in heterogeneous networks, OFDMA spectrum management and measurements, and game-theoretical optimization of cognitive networks.

Cognitive radio has been identified as a promising solution to the so-called spectrum scarcity problem. The basic idea of this paradigm is to allow unlicensed users to access in an opportunistic and non-interfering manner some licensed bands temporarily unoccupied by licensed users. Cognitive radio is expected to dramatically improve the efficiency of spectrum usage. However, before this paradigm can turn into reality, a full understanding of the spectrum dynamic usage in real wireless communications systems is required. Current spectrum utilization has already been evaluated in some measurement campaigns all over the world. However, to the best of the authors’ knowledge, no previous study has assessed the spectrum occupancy and the feasibility of the cognitive radio technology in different allocated spectrum bands under Spanish regulations. In this context, this paper presents a pioneer spectrum occupancy measurement in Spain conducted in the frequency range from 75 MHz to 7075 MHz in an outdoor environment in urban Barcelona. The measurements are analyzed and compared to the official spectrum regulations. The obtained results demonstrate the existence of a significant amount of spectrum available for the deployment of future cognitive radio networks.

This paper is aimed at presenting the real-time High Speed Packet Access (HSPA) emulator that has been developed in the framework of the AROMA project. Real-time emula- tors allow reproducing realistic scenarios to test algorithms, strategies, protocols and applications under realistic condi- tions. Therefore, real-time emulators constitute a powerful tool to evaluate the end-user's Quality of Experience (QoE), which could not be achieved by means of o -line simulations. The presented emulator is integrated in the AROMA real- time testbed, which has been developed to provide a frame- work for demonstrating the bene ts of the common radio re- source management algorithms as well as the proposed end- to-edge Quality of Service (QoS) management techniques developed for all-IP beyond 3G heterogeneous wireless net- works in the context of the AROMA project. This paper presents a qualitative description of the developed tool, em- phasizing some interesting implementation details that may result helpful in the development of similar emulation plat- forms. Some illustrative results, showing the capabilities of the developed tool, are also presented and analyzed.