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On the Deployment of Cognitive Relay as Underlay Systems
"... Abstract—The objective of this paper is to extend the idea of Cognitive Relay (CR). CR, as a secondary user, follows an underlay paradigm to endorse secondary usage of the spectrum to the indoor devices. To seek a spatial opportunity, i.e., deciding its transmission over the primary user channels, C ..."
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Abstract—The objective of this paper is to extend the idea of Cognitive Relay (CR). CR, as a secondary user, follows an underlay paradigm to endorse secondary usage of the spectrum to the indoor devices. To seek a spatial opportunity, i.e., deciding its transmission over the primary user channels, CR models its deployment scenario and the movements of the primary receivers and indoor devices. Modeling is beneficial for theoretical analysis, however it is also important to ensure the performance of CR in a real scenario. We consider briefly, the challenges involved while deploying a hardware prototype of such a system. I.
Paper Cooperative Games with Incomplete Information for Secondary Base Stations in Cognitive Radio Networks
"... be an effective solution for enhancing overall spectrum effi-ciency. Using CR technology fully involves the providing of incentives to Primary Radio Networks (PRNs) and revenue to the service provider so that Secondary Base Stations (SBSs) may utilize PRN spectrum bands accordingly. In this paper, a ..."
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be an effective solution for enhancing overall spectrum effi-ciency. Using CR technology fully involves the providing of incentives to Primary Radio Networks (PRNs) and revenue to the service provider so that Secondary Base Stations (SBSs) may utilize PRN spectrum bands accordingly. In this paper, a cooperative games with incomplete information for SBSs in a CR network is presented. Each SBS can cooperate with neighboring SBSs in order to improve its view of the spec-trum. Moreover, proposed game-theory models assume that the devices have incomplete information about their compo-nents, meaning that some players do not completely know the structure of the game. Using the proposed algorithm, each SBS can leave or join the coalition while maximizing its over-all utility. The simulation results illustrate that the proposed algorithm allows us to reduce the average payoff per SBS up to 140 % relative to a CR network without cooperation among SBSs. Keywords—Bayesian equilibrium, cognitive radio networks, game theory, wireless communication. 1.
Binary is Good: A Binary Inference Framework for Primary User Separation in Cognitive Radio Networks
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Sensing-based Spectrum Awareness in Cognitive Radio: Challenges and Open Research Problems
"... Abstract—Owing to the opportunistic nature of its oper-ation principle, the performance of Dynamic Spectrum Ac-cess/Cognitive Radio (DSA/CR) systems depends on the spectrum occupancy pattern of primary systems. DSA/CR systems can monitor periodically the occupancy state of licensed channels in order ..."
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Abstract—Owing to the opportunistic nature of its oper-ation principle, the performance of Dynamic Spectrum Ac-cess/Cognitive Radio (DSA/CR) systems depends on the spectrum occupancy pattern of primary systems. DSA/CR systems can monitor periodically the occupancy state of licensed channels in order to gain statistical information on their occupancy patterns, and exploit this information in decision-making processes. This paper provides an overview of relevant research topics related with the problem of providing DSA/CR systems with the ability to gain accurate, reliable and exploitable information on real-time spectrum occupancy. In particular, this paper reviews the following problems: i) spectrum sensing algorithms for spectrum occupancy estimation; ii) estimation of spectrum occupancy statistics based on spectrum sensing; and iii) statistical models for spectrum occupancy. Existing solutions are reviewed and open research problems are discussed as well. Keywords—Cognitive radio; dynamic spectrum access; spectrum awareness; spectrum sensing. I.
1Coalition Formation Games for Collaborative Spectrum Sensing
"... Abstract—Collaborative Spectrum Sensing (CSS) between sec-ondary users (SUs) in cognitive networks exhibits an inherent tradeoff between minimizing the probability of missing the detection of the primary user (PU) and maintaining a reasonable false alarm probability (e.g., for maintaining a good spe ..."
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Abstract—Collaborative Spectrum Sensing (CSS) between sec-ondary users (SUs) in cognitive networks exhibits an inherent tradeoff between minimizing the probability of missing the detection of the primary user (PU) and maintaining a reasonable false alarm probability (e.g., for maintaining a good spectrum utilization). In this paper, we study the impact of this tradeoff on the network structure and the cooperative incentives of the SUs that seek to cooperate for improving their detection performance. We model the CSS problem as a non-transferable coalitional game, and we propose distributed algorithms for coalition formation. First, we construct a distributed coalition formation (CF) algorithm that allows the SUs to self-organize into disjoint coalitions while accounting for the CSS tradeoff. Then, the CF algorithm is complemented with a coalitional voting game for enabling distributed coalition formation with detection probability guarantees (CF-PD) when required by the PU. The CF-PD algorithm allows the SUs to form minimal winning coalitions (MWCs), i.e., coalitions that achieve the target detection probability with minimal costs. For both algorithms, we study and prove various properties pertaining to network structure, adaptation to mobility and stability. Simulation results show that CF reduces the average probability of miss per SU up to 88:45 % relative to the non-cooperative case, while maintaining a desired false alarm. For CF-PD, the results show that up to 87:25 % of the SUs achieve the required detection probability through MWCs. I.
1Binary Inference for Primary User Separation in Cognitive Radio Networks
"... Abstract—Spectrum sensing receives much attention recently in the cognitive radio (CR) network research, i.e., secondary users (SUs) constantly monitor channel condition to detect the presence of the primary users (PUs). In this paper, we go beyond spectrum sensing and introduce the PU separation pr ..."
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Abstract—Spectrum sensing receives much attention recently in the cognitive radio (CR) network research, i.e., secondary users (SUs) constantly monitor channel condition to detect the presence of the primary users (PUs). In this paper, we go beyond spectrum sensing and introduce the PU separation problem, which concerns with the issues of distinguishing and characterizing PUs in the context of collaborative spectrum sensing and monitor selection. The observations of monitors are modeled as boolean OR mixtures of underlying binary sources for PUs. We first justify the use of the binary OR mixture model as opposed to the traditional linear mixture model through simulation studies. Then we devise a novel binary inference algorithm for PU separation. Not only PU-SU relationship are revealed, but PUs’ transmission statistics and activities at each time slot can also be inferred. Simulation results show that without any prior knowledge regarding PUs ’ activities, the algorithm achieves high inference accuracy even in the presence of noisy measurements. I.
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"... Abstract—For signaling and controlling a centralized Cognitive Radio Network (CRN) with users operating in different sets of channels, a dedicated common control channel is not a useful approach. Different strategies have been studied for this CRN control, some of them using time division mechanisms ..."
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Abstract—For signaling and controlling a centralized Cognitive Radio Network (CRN) with users operating in different sets of channels, a dedicated common control channel is not a useful approach. Different strategies have been studied for this CRN control, some of them using time division mechanisms. This is because employing a channel per each Cognitive Radio User (CRU) for simultaneously controlling them is not efficient. However, for signaling specific events to all CRUs in a CRN, the Central Cognitive Base Station (CCBS) needs to communicate to all the operating devices in the CRN domain. Reducing the number of broadcast signaling channels is then a need for good performance and energy efficiency of the CRN. In this paper, for the solution of this broadcasting signaling problem, each CRU is represented by an array considering its channel usability. Using this array, a static evaluation of the problem is initially performed. Then, the dynamic characteristics of CRNs are included to find an acceptable number of channels to communicate to every user in a specific CRN.
