Browsing by Author "Rauma, Tapio"
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Item Architecture and approach for obtaining spectrum availability information(2011) Matinmikko, Marja; Rauma, Tapio; Mustonen, Miia; Del Ser, Javier; IAThis paper presents a novel architecture and approach for obtaining spectrum availability information in future cognitive radio systems (CRS). CRS can opportunistically access spectrum by identifying unoccupied channels while keeping higher priority systems on the same channel free from harmful interference. Knowledge of the current state of the spectrum use is of utmost importance for CRS operations. There are different techniques for obtaining spectrum availability information including e.g. cognitive pilot channels, databases, spectrum sensing techniques, and combinations thereof. For spectrum sensing there are different algorithms and cooperative combining techniques with different characteristics and capabilities in terms of e.g. performance, complexity, and requirement of a priori information. This paper presents a unified architecture for selecting methods for obtaining spectrum availability information taking into account the operational environment and underlying policies. In addition, a novel low complexity heuristic decision making method is presented for selecting the spectrum sensing technique taking into account different capabilities and requirements while being adaptable to the changing environment.Item Decision-making system for obtaining spectrum availability information in opportunistic networks(2011) Matinmikko, Marja; Mustonen, Miia; Rauma, Tapio; Del Ser, Javier; IAOpportunistic networks with cognitive management systems can improve the resource use in future wireless communication networks by forming local clusters that are temporary extensions of the infrastructure and governed by the operator. This paper presents a decision making system that selects the techniques for obtaining spectrum availability information in opportunistic networks. The proposed decision making system selects the most suitable technique(s) from cognitive control channels, databases, and spectrum sensing techniques. Moreover, a novel and simple rule-based expert system is developed to choose the spectrum sensing technique among energy detection, correlation-based detection, and waveform-based detection. The selection is made based on the required probability of detection, operational SNR, available time, and available a priori information. The developed rule-based decision making system is presented in the form of a decision tree to illustrate the dominating paths that influence the decisions. Situations where none of the considered spectrum sensing techniques can meet the given conditions are identified and new approaches are proposed including cooperative sensing and changing of the channel. Results are presented to verify the functioning of the proposed decision making system and to show the relative frequencies of the different selected sensing techniques. Significant improvements can be obtained when the decision making system is used compared to using a single sensing technique instead.Item Fuzzy-logic based framework for spectrum availability assessment in cognitive radio systems(2013) Matinmikko, Marja; Del Ser, Javier; Rauma, Tapio; Mustonen, Miia; IAThis paper presents a novel decision-making system for the selection of methods to obtain knowledge of spectrum availability in future mobile communication systems equipped with cognitive radio system (CRS) capabilities. The proposed decision-making scheme selects the methods to obtain knowledge of spectrum availability between control channels, databases and spectrum sensing based on the specific requirements of the frequency band at hand. The developed decision-making system considers realistic frequency bands and spectrum sharing scenarios, including bands with primary allocation to mobile service where the operator governs the spectrum use, bands with co-primary or secondary allocation to mobile service where the primary users have to be protected from harmful interference, and finally license-exempt bands, where different systems coexist in uncontrolled interference conditions. Specifically, a novel rule-based decision-making system with a learning mechanism is developed to select among different spectrum sensing techniques including matched filtering, correlation detection, feature detection, energy detection, and cooperative sensing. The decision making system is further applied to operator-governed opportunistic networks, which are dynamically created temporary extensions of the mobile infrastructure networks. Performance evaluation is done by assuming changing operational conditions so as to elucidate the gains of the proposed decision making system with respect to the case when the sensing approach is kept fixed.