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This paper proposes the use of an overloaded hybrid MC-CDMA system to improve the spectral efficiency of Cognitive Radio (CR) network. The overlay transmission in the unused parts of the spectrum is full-loaded MC-CDMA signals with scrambling. The underlay signal, using a separate scrambling code from the overlay signals, utilizes the whole spectrum taking into account of the interference threshold...
In recent years Cognitive radio and UWB technologies are emerging for efficient use of Spectrum for short range wireless communications. FCC also has released a wideband of 7.5 GHz (From 3.1GHz to 10.6GHz) as unlicensed to use it anytime anywhere. In cognitive radio for sensing purpose and in UWB transceiver, UWB antennas play a vital role. Since antenna dimensions are frequency dependent, designing...
The basic notion behind Cognitive Radio (CR) is that secondary users (SU) access the under-utilized licensed spectrum of primary users (PU) in an opportunistic manner. It assuages the problem of spectrum scarcity, which is a major concern as many applications and devices nowadays are using wireless medium. Before carrying on any transmission, the SU senses the licensed spectrum and predicts whether...
Fast, accurate and efficient sensing is of important aspects in cognitive radio technology. A new sensing circuit is proposed using a phase frequency detector for cognitive radio applications. Using this method, spectral sensing can be done in a very short time by a low cost, low power circuit, compared with available implemented methods. The PFD circuit resolves different frequencies without the...
Cognitive radio networks can be designed to manage the radio spectrum more efficiently by utilizing the spectrum holes in primary user's licensed frequency bands. The currently available unlicensed spectrum is reaching its limit and various demands for applications and data rates in wireless communications requires additional spectrum which imposes limits on spectrum access. These requirements demand...
In a wireless regional area network (WRAN), the presence of wireless microphone (WM) signals must be detected as primary users. However, very narrow bandwidth and low power makes it difficult to sense WM signals especially when these WM signals are distributed in a wideband spectrum. In this paper, a singular value decomposition (SVD)-based approach is presented to sense and estimate multiple WM signals...
In a wireless regional area networks (WRAN) network, the presence of a wireless microphone (WM) signal must be detected as a primary user. However, very narrow bandwidth and low power makes it difficult to sense a WM signal. In this paper, a singular value decomposition (SVD)-based approach is presented to sense and estimate a WM signal. After performing SVD on the received data matrix, the presence...
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...
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