Designing non-contiguous orthogonal frequency division multiplexing transceiver based on wavelet transform and removable cyclic prefix for spectrum sharing in cognitive radio systems

2014 ◽  
Vol 8 (9) ◽  
pp. 1508-1517 ◽  
Author(s):  
Damoon Shahbaztabar ◽  
Hamid Farrokhi
Keyword(s):  
Wavelet Transform ◽  
Cognitive Radio ◽  
Orthogonal Frequency Division Multiplexing ◽  
Spectrum Sharing ◽  
Cyclic Prefix ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Cognitive Radio Systems ◽  
Radio Systems

scholarly journals The effect of wavelet transform on OFDM system in modern cellular networks

2019 ◽  
Vol 15 (1) ◽  
pp. 324
Author(s):  
Mayada Faris Ghanim
Keyword(s):  
Fourier Transform ◽  
Wavelet Transform ◽  
Wireless Communications ◽  
Cellular Networks ◽  
Orthogonal Frequency Division Multiplexing ◽  
Cyclic Prefix ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Ofdm System

Wavelet transform has many advantages that make it suitable and efficient approach to replace Fast Fourier Transform (FFT) in conventional Orthogonal Frequency Division Multiplexing (OFDM) systems. Wavelet transform is employed in modern cellular networks to remove the use of cyclic prefix, which leads to decreasing the bandwidth losses and the power of transmission. Wavelet based OFDM system is designed in order to overcome the drawbacks of OFDM system so that the proposed system is good candidate for next generation wireless communications.

A planar UWB antenna based on MB-OFDM applications with switchable dual band-notched for cognitive radio systems

2014 ◽  
Vol 8 (1) ◽  
pp. 95-102 ◽  
Author(s):  
Vahid Sharbati ◽  
Pejman Rezaei ◽  
Ali Shahzadi ◽  
Mohammad M. Fakharian
Keyword(s):  
Cognitive Radio ◽  
Orthogonal Frequency Division Multiplexing ◽  
Simple Structure ◽  
Dual Band ◽  
Frequency Division ◽  
Uwb Antenna ◽  
Compact Size ◽  
Cognitive Radio Systems ◽  
Radio Systems ◽  
Left And Right

In this paper, a switchable antenna with capability to operate in ultrawideband (UWB) frequency from 3 to 10.7 GHz with two switchable notch bands of 3.3–3.7 and 3.7–4.2 GHz, is presented for cognitive radio (CR) and multiband orthogonal frequency-division multiplexing (MB-OFDM) applications. The proposed antenna has a simple structure and compact size of 17 × 24 mm2. The antenna in the UWB characteristics is obtained using a circular radiator patch with an embedded T-slot on the patch and a rectangular parasitic element that is attached to the patch. The reconfigurability is also achieved by two L-shaped parasitic elements placed in the left and right of the patch that two ideal switches is inserted over the these elements and the circular patch. The function of the antenna can be changed by tuning status of the switches that make the notch bands in application frequencies. The measurement and simulation results show that the antenna has good characteristics for CR application and MB-OFDM, where the UWB antenna is required for spectrum sensing and the switchable band rejection antenna is used for reconfigurable operation.

scholarly journals Suppression of Mutual Interference in Noncontiguous Orthogonal Frequency Division Multiplexing Based Cognitive Radio Systems

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Atif Elahi ◽  
Ijaz Mansoor Qureshi ◽  
Fawad Zaman ◽  
Noor Gul ◽  
Tahir Saleem
Keyword(s):  
Cognitive Radio ◽  
Orthogonal Frequency Division Multiplexing ◽  
Spectrum Sharing ◽  
Dynamic Spectrum Access ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Secondary Users ◽  
Generalized Sidelobe Canceller ◽  
Suppression Technique ◽  
Sidelobe Canceller

Orthogonal frequency division multiplexing (OFDM) is a favourable technology for dynamic spectrum access (DSA) due to the flexibility in spectrum shaping. In spite of that, high sidelobes of OFDM subcarriers bring in considerable interference to the nearby users, particularly in OFDM based cognitive radio (CR) networks, where the secondary users (SUs) are capable of accessing the spectrum opportunistically. In this paper, two new techniques for the suppression of high sidelobes are proposed. The proposed techniques composed of an optimization scheme are followed by generalized sidelobe canceller. The proposed techniques can be considered as a two-level suppression technique in the sense that in the first level the sidelobe is reduced by using cancellation carriers (CCs), whose amplitudes are determined using genetic algorithm (GA) and differential evolution (DE), while in the second level further reduction of sidelobe is achieved using generalized sidelobe canceller (GSC). Simulation results show the power spectral density (PSD) performance of the proposed techniques in comparison with already existing techniques, demonstrating that the proposed techniques minimize the out-of-band radiation (OOBR) significantly, thus qualifying for more effective spectrum sharing.

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