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Cognitive radio is an emerging technology that aims for efficient spectrum usage by allowing unlicensed (secondary) users to access licensed frequency bands under the condition of protecting the licensed (primary) users from harmful interference. The latter condition constraints the achievable throughput of a cognitive radio network, which should therefore access a wideband spectrum in order to provide...
This paper investigates the problem of uplink subcarrier and power allocation in a Cognitive Radio (CR) network that operates opportunistically within vacant licensed Primary Users (PUs)spectrum. The resource allocation algorithm aims to maximize the CR network throughput under PUs interference constraints. In this paper, CR interference introduced into PUs sub-bands is modeled as a composite of two...
Deploying femtocell networks embedded in the Macrocell coverage greatly benefits communication quality in variety manners. However, the lack of schemes to effectively mitigate detractive interference, fully utilize radio resources and provide quality-of-service (QoS) guarantee (in terms of delay) creates challenges to practically facilitate the concept of femtocell. To tackle these challenges to achieve...
In this paper, we investigate the optimal power allocation strategy in the joint spectrum overlay and underlay cognitive radio network where a licensee and multiple unlicensed users coexist and operate in the same spectrum. We propose an optimal power allocation scheme which achieves the maximum system utility while satisfying the QoS requirement of SUs and interference constrains of the PU. Particularly,...
As wireless systems continue to proliferate, interference management is becoming a concern in both military and commercial domains. This paper introduces a novel cognitive coexistence framework between infrastructure and ad hoc networks. Based on sensing and predicting the ad-hoc networkpsilas activity, the infrastructure system allocates power and transmission time such as to minimize its impact...
To take advantage of time-varying spectrum opportunities, a cognitive radio (CR) user continuously monitors the dynamic usage of the licensed frequency band and is allowed to utilize the spectrum resource when it does not cause unacceptable interference with licensed users. In this paper, the transmit power control scheme for each data transmission between periodic spectrum sensing activities is proposed...
In this paper, we propose a cognitive radio-based multi-user resource allocation framework for mobile ad hoc networks using multi-carrier DS CDMA modulation over a frequency-selective fading channel. In particular, given pre-existing communications in the spectrum where the system is operating, in addition to potential narrow-band interference, a channel sensing and estimation mechanism is provided...
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