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We propose a simple method for the generation of signature matrices for a space-time spreading (STS) system with BPSK modulation, where a signature sequence assigned to a user is paritioned into segements and the segments are assigned to the transmit antennas of the user. We show that, if the signature sequences are linearly independent, the STS system does not has an error floor in its BER performance...
In cognitive radio system, the licensed spectrum resource that is not been used by the primary users could be reused opportunistically by the unlicensed secondary users. Spectrum sensing is the fundamental task in cognitive radio system for the secondary system should detect the available idle spectrum resource accurately and timely. Performance of traditional blind spectrum sensing is limited by...
In cognitive radio, the licensed spectrum resource that is not been used by primary users at the current time and location could be reused by secondary users. Spectrum sensing is the fundamental task in cognitive radio for the cognitive system should detect the available idle spectrum resources accurately and timely. The performance of traditional blind spectrum sensing is limited by the influence...
Spectrum sensing is one of the most important functions for cognitive radio. The performance of some sensing techniques like energy detection is determined by receiving signal to noise ratio (SNR). We applies antenna array using multiple beams to primary user detection. Whole space around cognitive user is divided into several subspaces for multiple beams. The directional beam can improve spectrum...
Cooperative spectrum sensing among cognitive radio nodes is needed in order to overcome fading and shadowing effects on individual cognitive user and to increase the reliability and efficiency of spectrum sensing. When communication is under bandwidth constraint, spectrum sensing sensor nodes normally only send one bit report to fusion center and censoring detection method is employed by sensor nodes...
This paper investigates the optimal weighting scheme for cooperative spectrum sensing in cognitive radio networks, under the constraint of equal probabilities of false alarm and miss detection. The derived optimal weights are determined by individual signal-to-noise-ratio (SNR) of each cooperative sensing node. However, to obtain the precise realistic measurement of each node's SNR is somehow impractical...
Energy detection based spectrum sensing has been proposed and studied widely for primary user (PU) signal detection in the literature. With the help of multiple secondary users (SU) in the cognitive radio network, various cooperative sensing schemes are investigated to enhance the energy detection performance. However, the impacts of noise power fluctuating effects on the detection performance in...
Cooperation between cognitive radio nodes is indispensable in order to mitigate the sensitivity requirement on individual radio and increase the reliability of spectrum sensing. Normally the fusion network is in parallel configuration and the conventional fusion rules are the k out of N rules because of their simplicity to manage. When the detection nodes are similar with each other i.e. their observations...
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