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Cognitive radio (CR) is considered as a key enabling technology for dynamic spectrum access to improve spectrum efficiency. Although the CR concept was invented with the core idea of realizing "cognition", the research on measuring CR cognition capabilities and intelligence is largely open. Deriving the intelligence capabilities of CR not only can lead to the development of new CR technologies,...
In this paper, we propose an analysis framework for the performance of heterogeneous cognitive radio networks with multiple different secondary users (SU) coexisting and competing for spectrum access. In order to model the operation of different SUs in a feasible manner, we use a bank of Markov models, where each SU is modeled by a separate Markov model. The individual Markov models are connected...
In this paper, we propose a method to calculate the throughput of multiple uncooperative cognitive radio users. We use a bank of Markov models to derive the fraction of time that each user spends in successful channel access. The mutual interference among the users is modeled into the transitional probabilities of the Markov models, which makes it tractable to calculate multiple user throughput in...
In this paper we give closed-form analysis results of the jamming probabilities and throughput of cognitive radio transmissions when facing a wideband jammer. We first set up a Markov model of the cognitive radio transmissions which consists of three states: spectrum sensing, channel access, and channel switching. The jamming probabilities of the three states are derived under the assumption of a...
In this paper, we study both the jamming capability of the cognitive-radio-based jammers and the anti-jamming capability of the cognitive radio networks. We first setup the models of cognitive-radio-based jammers and the cognitive radio network transmissions. We then analyze various jamming attack strategies where the jammer spends various powers in order to jam various transmission slots of the cognitive...
One of the major challenges to cognitive radios is the synchronization of distributed radios onto the same spectrum white spaces which vary in time and space. In this paper, we propose a frequency-hopping spread spectrum transmission scheme which works reliably without any a priori handshaking assumption. Each cognitive radio independently detects white spaces, and then selects one of them to transmit...
In this paper, we analyze the allowable transmission power of cognitive radios when used as secondary users in a dynamic spectrum access network. Closed-form upper and lower bounds are derived, while accurate solutions to transmission power are available through numerical evaluation. The transmission power depends on the distance between primary and secondary transmitters as well as the number of...
Cognitive radio is a desirable technique for secondary users to utilize the spectrum gray space. In order to avoid intolerable interference to primary users, the transmission power of cognitive radios must be carefully managed. In this paper, we analyze the sum transmission power of a group of randomly distributed but fully cooperated secondary transmitters in a network consisting of one primary transmitter...
One of the major concerns of cognitive radios when used for secondary spectrum access is the potential of interfering primary users, considering especially that cognitive radios may be misbehaved or under malicious attacks. In this paper, we present a method for a cognitive radio to secure its transmission power purely from its physical-layer received signals. Built into the transceiver hardware as...
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