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Spectrum sensing is a key component of cognitive radio (CR) system to understand its radio frequency (RF) environment. One critical challenge in spectrum sensing is detection of weak signals in particular in an indoor environment. Distributed spectrum sensing can address this shortcoming by providing a combined data from spatially distributed sensors. This approach often achieves higher sensitivity...
This paper addresses the transmit power control with multiple antennas. A theoretical comparison of transmit diversity and beamforming techniques in the presence of fading correlation at an antenna array and handoff is presented. The objective is to investigate transmit power of both system and investigate the effect of array perturbations that exist in practical applications of antenna arrays. The...
In this paper we investigate spectrum sensing for cognitive radio (CR) by using multiple spectrum sensors. We explore sensing schemes based on soft information combining, hard information combining and a two-stage detection scheme that uses both soft information combining and hard information combining. The two-stage detection scheme is shown to provide improved performance compared to sensing based...
AbstraAbThis study addresses detection of primary users (PUs) for cognitive radio system (CRS) with distributed spectrum sensors (DSSs) in Rayleigh fading environment. Two sensing schemes using DSSs that employ energy detection (ED) are investigated as cooperative sensing and collaborative sensing. For the cooperative sensing, each DSS makes hard decision after sensing and transmits the information...
Recent studies on spectrum sensing for cognitive radio (CR) reveal that sensing based on single CR may not provide reliable information due to the fact that signals degrade as a result of fading and shadowing. Hence, spectrum sensing based on multiple CR has been considered. In this paper we investigate a distributed sensing based on multiple spectrum sensors where the sensors are located outside...
A turbo network coding based relay model and its decoding method are proposed for the quasi-static fading multi-access up-link channel. In the model a relay assists two mobile nodes simultaneously by forwarding a network coded version of the two interleaved messages. Access Point (AP) performs joint channel and network decoding with signals received from two mobile nodes and the relay. Compared with...
A novel scheme that jointly utilizes switched beam antennas in double-directional radio channel (DDRC) is proposed. Employing directional beam pattern at both transmitter (Tx) and receiver (Rx) sides in DDRC provides distributed directivity gain (DDC). Jointly switching directional patterns at both ends provides extra diversity gain. We employ two electronically steerable parasitic array radiator...
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