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This Paper describes optimal side lobe level of an elliptical cylindrical array for uniform excited isotropic antennas and non-uniform excited isotropic antennas when compared to concentric elliptical array using particle swarm optimization. Particle swarm optimization (PSO) could be a computational technique that optimizes a problem by iteratively making an attempt to enhance a candidate solution...
A cooperative relaying scheme is proposed for an underlay cognitive radio network where relays use their beam steering capability to impose target SINRs at the secondary user terminals whilst keeping the interference and noise leakage to the primary users below a threshold. The scheme is developed to incorporate per relay antenna power constraint that limits the power emitted by the relays. The scheme...
Cognitive radio networks opportunistically operate in frequency bands that have been licensed to other networks. Therefore, communication between unlicensed users should ensure the interference leaked to the licensed users is kept below an acceptable level while achieving the required quality of services. In this paper, we extend SINR balancing technique to serve multiple cognitive users in the downlink...
Cognitive radio networks have the ability to efficiently utilize the radio spectrum by allowing unlicensed users to communicate in the licensed frequency bands. Transmit beamformers can be designed by setting constraints on the interference temperature of the licensed users and signal to interference and noise ratios (SINRs) of the cognitive users. This design is however very sensitive to errors in...
Cognitive radio networks have the ability to efficiently utilize the scarce radio spectrum by allowing unlicensed users to access the licensed frequency bands in the absence of licensed users. Transmit beamformers can be designed by setting constraints on the interference temperature of the licensed users and signal to interference and noise ratios (SINRs) of the cognitive users. This design is however...
Cognitive radios have the ability to efficiently utilize the spectrum, by intelligently sensing absence of licensed users and transmitting signal through the frequency bands that are not occupied. Spatial diversity techniques at the cognitive base station could further help in controlling the interference temperature levels of the licensed users when signals are transmitted to unlicensed users. This...
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