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In a spectrum-sharing system (SSS), deploying the antennas in a distributed manner can provide a new spatial dimension for the efficient reuse of licensed frequency bands. In order to improve the sum rate of multiple secondary-users (SUs), this paper addresses the problem of coordinated multi-SU spectrum sharing in a distributed antenna-based SSS. By adopting the Hungarian method and the primal decomposition...
In this paper, joint beamforming and power allocation via cooperation feedback and local feedback is considered in cognitive radio (CR) downlink where primary user (PU) coexists with multiple secondary users (SUs). The objective is to maximize the sum-rate of SUs while satisfying interference power constraint to PU and the total transmission power constraint of SUs. To effectively mitigate the interference...
We propose a cooperative spectrum sharing strategy in which the secondary system can access to the licensed spectrum of the primary system if it can help the primary system achieve the target rate. Specifically, the secondary system acts as a decode-and-forward relay for the primary system by splitting a fraction of its transmission bandwidth to help forward primary signal. It uses the remaining bandwidth...
This paper presents an analytical study on the outage performance of cognitive decode-and-forward (DF) two-way relaying networks with underlay spectrum sharing. The bidirectional protocol, i.e., two time-slot multiple access broadcast (MABC) and three time-slot time division broadcast (TDBC), are considered. We propose a definition of outage probability by jointly considering outage events in the...
In this paper, we propose an anti-interference cooperative spectrum sharing strategy in cognitive two-phase full-duplex relaying networks, in which the secondary system acts as a decode-and-forward relay to assist the primary system achieve the target transmission rate. As a reward, the secondary system can gain access to the licensed primary spectrum to transmit its own signal in both two phases...
Cognitive spectrum sensing is a key technology to improve the spectrum utilization and meanwhile decrease the possibility of interfering the primary users(PUs). Based on the cooperation of several cognitive radio sensors(CRSs), the channel fading and hidden terminal problems are avoided. The performance of detection has great relevance with the algorithm of combining the data from different CRSs....
In this paper we consider a cognitive radio (CR) communication system based on spectrum sharing schemes, where we have a secondary user (SU) link with multiple transmitting antennas and a single receiving antenna, coexisting with a primary user (PU) link with a single receiving antenna. At the SU transmitter (SU-Tx), the channel state information (CSI) of the SU link is assumed to be perfectly known;...
Available spectrum resources are becoming scarcer, while additional services are being integrated into wireless devices. Cognitive radio and multiple-antenna (MIMO) techniques can be combined to provide a solution to this dilemma. Given the currently available frequency bands and a set of bit-rate constrained services to be transmitted, the antennas can be partitioned among frequency bands and the...
Cooperative energy spectrum sensing has been proved effective to detect the spectrum holes in Cognitive Radio (CR). However, its performance may suffer from the noise uncertainty, which is portrayed by the SNR wall in some literatures. In this paper we analyze the spectrum sensing performance under noise uncertainty and propose a new approach to obtain the SNR wall. In addition, a suboptimal liner...
Cooperative energy spectrum sensing has been proved effective to detect the spectrum holes in Cognitive Radio (CR). However, few studies make mention of wavelet transform based signal processing before energy detection. In this paper, a novel cooperative energy spectrum sensing algorithm with 1-D or 2-D wavelet denoising is proposed. The 1-D wavelet denoising is performed at each sensing node, while...
Opportunistic spectrum access system allows the secondary user to access spectrum holes not being utilized by the primary user. Traditional opportunistic spectrum access approaches only sense and utilize current spectrum holes. This can result in uncontrollable collision probability, which exceed the maximum collision probability allowed by the primary user network. In this paper, we consider a cognitive...
In OFDM-based cognitive radio systems, the interference power limits of the primary users (PUs) introduce subchannel transmit power constraints for the secondary user (SU). The power allocation among the subcarriers of SU should be subject to both the sum transmit power constraint as well as the transmit power constraint of each subchannel. Different from previous works, we deal with a more general...
In this paper, we consider a model of two-user channel with one primary user and one secondary user. Then we present a novel power control approach based on ε-greedy Monte Carlo method to solve transmit-power control problem of the secondary user. Theoretical analysis and simulation results both show that the approach can not only optimize transmit-power control of the secondary user, but also be...
In cognitive radio (CR) systems, secondary users (SUs) have to detect the channel periodically during their data transmission to decide whether the channel is idle in order to avoid unacceptable interferences to primary users (PUs). The duration of the detection process in a cycle affects the channel efficiency of the SU. Also, the detection time needs to be adaptively adjusted due to path loss variations...
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