Topic
Cognitive network
About: Cognitive network is a research topic. Over the lifetime, 4213 publications have been published within this topic receiving 107093 citations.
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TL;DR: The design of minimum cost networks with a given availability is discussed for different models of the cost-availability function in the links and algorithms are given for its exact or approximate evaluation.
Abstract: In order to design an available network efficiently, a parameter characterizing the network availability is needed. The global availability is suggested and algorithms are given for its exact or approximate evaluation. The design of minimum cost networks with a given availability is discussed for different models of the cost-availability function in the links. Some example network optimizations are reported.
32 citations
19 May 2008
TL;DR: Three cooperative spectrum access schemes for secondary users under average delay constraint are proposed, based on the assumption that both the primary and secondary transmitter employ rateless coding, and the average throughput of the secondary user for each scheme is calculated and compared both analytically and numerically.
Abstract: In cognitive networks, since the secondary users are not licensed owners of the spectrum, they can only access the spectrum opportunistically and cooperatively to exploit the best effort throughput for themselves while guaranteeing that their transmissions would not break the QoS performance of the primary communications. In this paper, we consider the cognitive network in which the primary users have delay sensitive services, e.g., voice or video services, and we take the average delay constraint as primary users' QoS requirement. Three cooperative spectrum access schemes for secondary users under such constraint are proposed, based on the assumption that both the primary and secondary transmitter employ rateless coding. The average throughput of the secondary user for each scheme is calculated and compared both analytically and numerically. The impacts of system parameters and network topology on these schemes are also illustrated via numerical simulations.
32 citations
TL;DR: The jointly optimal allocation of sensing time and power for a two-user amplify-and-forward overlay cognitive network is developed by maximizing the averaged aggregate throughput of the secondary network.
Abstract: The jointly optimal allocation of sensing time and power for a two-user amplify-and-forward overlay cognitive network is developed by maximizing the averaged aggregate throughput of the secondary network In particular, observing that the sensing duration lies within a strict interval, the jointly optimal strategy of sensing time and power allocation is proved to be tractable by sequential optimization
31 citations
01 Jan 2012
TL;DR: This paper briefly illustrates how a unique combination of methods from cognitive robotics, agent control systems, wireless sensor networks and machine learning are being extended, integrated, and applied to AAL applications.
Abstract: Robotic ecologies are networks of heterogeneous robotic devices pervasively embedded in everyday environments, where they cooperate to perform complex tasks. While their potential makes them increasingly popular, one fundamental problem is how to make them self-adaptive, so as to reduce the amount of preparation, pre-programming and human supervision that they require in real world applications. The EU FP7 project RUBICON develops self-sustaining learning solutions yielding cheaper, adaptive and efficient coordination of robotic ecologies. The approach we pursue builds upon a unique combination of methods from cognitive robotics, agent control systems, wireless sensor networks and machine learning. This paper briefly illustrates how these techniques are being extended, integrated, and applied to AAL applications.
31 citations
TL;DR: This work considers beamforming in a cognitive network with multiple primary users and a secondary user sharing the same spectrum and shows that the average interference per primary receiver converges to E[d-alpha], the expected value of the path loss in the network, whereas the average CSIR decays as 1/c when c = Np/Nt rarrinfin.
Abstract: We consider beamforming in a cognitive network with multiple primary users and a secondary user sharing the same spectrum. Each primary and secondary user consists of a transmitter and a receiver. In particular, we assume that the secondary transmitter has Nt antennas and transmits data to its single-antenna receiver using beamforming. The beamformer is designed to maximize the cognitive signal-to-interference ratio (CSIR). Using mathematical tools from random matrix theory, we derive both lower and upper bounds on the average interference created by the cognitive transmitter at the primary receivers and the average CSIR of the cognitive user. We further analyze and prove the convergence of these two performance measures asymptotically as the number of antennas Nt or primary users Np increases. Specifically, we show that the average interference per primary receiver converges to E[d-alpha], the expected value of the path loss in the network, whereas the average CSIR decays as 1/c when c = Np/Nt rarrinfin. In the special case of Nt / Np, the lower bound of the average total interference approaches 0 and the upper bound of the average CSIR approaches NtE[d-alpha]/alpha2c where alpha2c is the noise variance at the cognitive receiver.
31 citations