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

Field Measurements in Determining Incumbent Spectrum Utilization and Protection Criteria in Wireless Co-existence Studies

Studies of spectrum sharing and co-existence between different wireless communication systems are important, as the current aim is to optimize their spectrum utilization and shift from static exclusive spectrum allocation to more dynamic co-existence of different systems within same frequency bands. The main goal of this thesis is to provide measurement methodologies for obtaining realistic results in modeling incumbent spectrum utilization and in determining incumbent protection criteria. The following research questions are considered in this thesis: Q1) How should field measurements be conducted and used to model incumbent spectrum utilization? Q2) How should field measurements be conducted and used to determine protection criteria for incumbents in a co-existence scenario with mobile broadband? and Q3) Which licensing methods and technological solutions are feasible to enable spectrum sharing in frequency bands with incumbents? To answer to Q1, this thesis describes the development of a spectrum observatory network concept created through international collaboration and presents measurement methodologies, which allow to obtain realistic spectrum occupancy data over geographical areas using interference map concept. A cautious approach should be taken in making strong conclusions from previous single fixed location spectrum occupancy studies, and measurements covering larger geographical areas might be needed if the measurement results are to be used in making spectrum management decisions. The field interference measurements considered in Q2 are not covered well in the current research literature. The measurements are expensive to conduct as they require substantial human resources, test network infrastructure, professional level measurement devices and radio licenses. However, field measurements are needed to study and verify hypotheses from computer simulations or theoretical analyses in realistic operating conditions, as field measurement conditions can not or are not practical to be adequately modeled in simulations. This thesis proposes measurement methodologies to obtain realistic results from field interference measurements, taking into account the propagation environments and external sources of interference. Less expensive simulations and laboratory measurements should be used both to aid in the planning of field measurements and to complement the results obtained from field measurements. Q3 is investigated through several field interference measurement campaigns to determine incumbent protection criteria and by analyzing the spectrum observatory data to determine the occupancy and trends in incumbent spectrum utilization. The field interference measurement campaigns have been conducted in real TV White Space, LTE Supplemental Downlink and Licensed Shared Access test network environments, and the obtained measurement results have been contributed to the development of the European spectrum regulation. In addition, field measurements have been conducted to contribute to the development and technical validation of the spectrum sharing frameworks. This thesis also presents an overview of the current status and possible directions in spectrum sharing. In conclusion, no single spectrum sharing method can provide universally optimal efficiency in spectrum utilization. Thus, an appropriate spectrum sharing framework should be chosen taking into account both the spectrum utilization of the current incumbents and the future needs in wireless communications.Siirretty Doriast

Distributed radio map reconstruction for 5G automotive

Se espera que los mapas de entorno radio sean una herramienta esencial para la optimización y gestión de recursos del 5G en vehículos. En este trabajo, consideramos el problema de la reconstrucción del mapa de entorno radio utilizando una red de sensores inalámbricos formada por nodos sensores en vehículos, nodos de acceso de una infraestructura de ciudad inteligente, etc. Debido a las limitaciones de recursos en las redes de sensores, es crucial seleccionar un pequeño número de mediciones de los sensores para reconstruir el campo. En este contexto, presentamos un novedoso algoritmo distribuido basado en el método de regresión Kriging para la reconstrucción del mapa de entorno radio en términos de potencia media recibida en lugares donde no se dispone de mediciones de los sensores. Los componentes de pérdida de trayectoria y de sombra del canal inalámbrico se estiman por separado. Para la estimación de las pérdidas por sombra, se forman grupos de sensores de forma adaptativa y su tamaño se optimiza en en términos del menor número de sensores posible minimizando la varianza ordinaria de Kriging. Se obtiene la complejidad del algoritmo propuesto y se presentan resultados de simulación para mostrar la eficacia del algoritmo para la reconstrucción del campo.GRISOLIA/2012/028, RACHEL TEC2013-47141-C4-4-RRadio maps are expected to be an essential tool for the resource optimization and management of 5G automotive. In this paper, we consider the problem of radio map reconstruction using a wireless sensor network formed by sensor nodes in vehicles, access nodes from a smart city infrastructure, etc. Due to limited resource constraints in sensor networks, it is crucial to select a small number of sensor measurements for field reconstruction. In this context, we present a novel distributed incremental clustering algorithm based on the regression Kriging method for radio map reconstruction in terms of average received power at locations where no sensor measurements are available. The path-loss and shadowing components of the wireless channel are separately estimated. For shadowing estimation, clusters of sensors are adaptively formed and their size is optimized in terms of the least number of sensors by minimizing the ordinary Kriging variance. The complexity of the proposed algorithm is analyzed and simulation results are presented to showcase the algorithm efficacy to field reconstruction

SMARAD - Centre of Excellence in Smart Radios and Wireless Research - Activity Report 2011 - 2013

Centre of Excellence in Smart Radios and Wireless Research (SMARAD), originally established with the name Smart and Novel Radios Research Unit, is aiming at world-class research and education in Future radio and antenna systems, Cognitive radio, Millimetre wave and THz techniques, Sensors, and Materials and energy, using its expertise in RF, microwave and millimeter wave engineering, in integrated circuit design for multi-standard radios as well as in wireless communications. SMARAD has the Centre of Excellence in Research status from the Academy of Finland since 2002 (2002-2007 and 2008-2013). Currently SMARAD consists of five research groups from three departments, namely the Department of Radio Science and Engineering, Department of Micro and Nanosciences, and Department of Signal Processing and Acoustics, all within the Aalto University School of Electrical Engineering. The total number of employees within the research unit is about 100 including 8 professors, about 30 senior scientists and about 40 graduate students and several undergraduate students working on their Master thesis. The relevance of SMARAD to the Finnish society is very high considering the high national income from exports of telecommunications and electronics products. The unit conducts basic research but at the same time maintains close co-operation with industry. Novel ideas are applied in design of new communication circuits and platforms, transmission techniques and antenna structures. SMARAD has a well-established network of co-operating partners in industry, research institutes and academia worldwide. It coordinates a few EU projects. The funding sources of SMARAD are diverse including the Academy of Finland, EU, ESA, Tekes, and Finnish and foreign telecommunications and semiconductor industry. As a by-product of this research SMARAD provides highest-level education and supervision to graduate students in the areas of radio engineering, circuit design and communications through Aalto University and Finnish graduate schools. During years 2011 – 2013, 18 doctor degrees were awarded to the students of SMARAD. In the same period, the SMARAD researchers published 197 refereed journal articles and 360 conference papers