Jaakko Ojaniemi - IEEE Xplore Author Profile

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Since the introduction of the idea of cognitive radio, various approaches towards spectrum sharing have been considered, for example, the Licensed Shared Access (LSA), which is considered in Europe, or Citizens Broadband Radio Service (CBRS) with Spectrum Access System (SAS) regulated by the US. This paper deals with the problem of coordinated resource allocation among a set of available base stat...Show More
Dynamic spectrum access is considered as a valuable tool for increasing spectrum utilization in future wireless networks. Although in 5G the focus is on exclusive licensing, the possibility for flexible spectrum usage is also considered. In this paper, we present the results of extensive field trials carried in Poznan, Poland, to demonstrate advanced spectrum sharing options. The experiments have ...Show More
Spectrum management is a key challenge in the domain of wireless network virtualization. An efficient tool is needed to support dynamic, yet policy-compliant allocation of the frequency resources in virtual networks. In this article, we discuss the idea of a spectrum management application (SMA) as a tool for solving this technoeconomic issue in virtualized networks. The generic idea is exemplifie...Show More
This paper presents a trial on sharing spectrum between different actors in a flexible manner in 2.3 GHz band. Trial demonstrates a flexible use of shared spectrum providing means for the broadcasters and other Programme Making and Special Events (PMSE) stakeholders to gradually upgrade their equipment towards LTE/5G radio based equipment.Show More
In order to provide meaningful data about spectrum use, occupancy measurements describing the utilization rate of a specific frequency band should be conducted over a specific area instead of a single location. This paper presents a comprehensive methodology for the measurement and analysis of spectrum occupancy. This paper surveys spectrum measurement campaigns and associated interference maps, i...Show More
This work focuses on the implementation of dynamic spectrum access in a scenario where the existing wireless infrastructure is shared by a secondary cellular system. We study the optimization of the physical antenna configuration of the secondary-system base stations, assuming that these antennas are deployed at the transmitter sites of a primary broadcast network. Specifically, we maximize the th...Show More
This paper focuses on evaluating the gains obtained through cooperative spectrum sensing in the real world while using cyclostationary-based mobile sensors. In cooperative sensing (CS), different secondary users (SUs) in a geographical neighborhood cooperate to detect the presence of a primary user (PU). Compared with single-user sensing, cooperation provides diversity gains in the face of multipa...Show More
Cognitive radio systems aim to take advantage of the spatiotemporal empty spectrum without causing harmful interference towards the primary network by utilizing knowledge of the prevailing radio environment. The radio environment is typically modeled with propagation models or by interpolating spatially distributed field measurement data. This paper presents a practical online data assimilation me...Show More
In a cognitive radio system, awareness of the prevailing radio environment of the primary network, such as digital terrestrial television, is important since it governs the emission limits for the secondary system devices. Field strength estimates of the primary network are typically computed using terrain based radio propagation models, or by using univariate interpolation techniques to approxima...Show More
White spaces are locally or temporally available frequencies that are principally reserved for primary use such as TV broadcasting. The currently prevalent view to the utilization of such spectrum resources is that white space devices must query a geolocation database to obtain information about available frequencies and related maximum transmission powers. A geolocation database is fundamentally ...Show More
According to the European Electronic Communications Committee a practical approach for constructing a cognitive radio network operating in TV white spaces is based on geolocation databases. The practical communication rates achievable for the secondary users and the interference caused to the primary system are fundamentally limited by the information the database has on the geographical distribut...Show More
We present a method for modeling OFDM transmission over time- and frequency-selective fading channels using finite-state hidden Markov models. The proposed approach has improved fading autocorrelation accuracy compared to previous related models. Also, we present a way of producing log likelihood ratio values as output of the finite-state model for any signal constellation. As a case study, we con...Show More
This paper presents the application of two non-linear methods for the localization of transient artifacts on trend data. The first method is based on the matching pursuit method. The second is a multi-dimensional technique which makes use of a particular neural network, namely the marginal median linear vector quantizer. The application concerns trend data issued from monitored pulmonary artery pr...Show More
Well-characterized and comprehensive test data sets are essential in the development and evaluation of biosignal interpretation methods for intensive-care patient monitoring. The IMPROVE (IMPROVing control of patient status in critical carE) data library is an annotated data library that contains practically all the monitored and other clinical data from critically ill patients at high risk of oxy...Show More