A critical objective of cognitive radio (CR) system is to enhance the spectrum efficiency, and one of the key factors that can determine the spectrum efficiency is the system spectrum sensing performance with respect to sensing window length. For non-coherent detection-based sensing technique, the length of the sensing window required to meet the detection criteria is inversely proportional to ...

Adaptive Transmission Schemes for Spectrum Sharing Systems: Trade-offs and Performance Analysis Zied Bouida, PhD. Concordia University, 2015 Cognitive radio (CR) represents a key solution to the existing spectrum scarcity problem. Under the scenario of CR, spectrum sharing systems allow the coexistence of primary users (PUs) and secondary users (SUs) in the same spectrum as long as the interfer...

In cognitive radio adhoc networks the utilization of spectrum without spectrum sensing is a difficult task because of the fluctuations of the availability of spectrum holes. Hence the location awareness is must for concurrent transmission area where both primary users and secondary users can exists. In this paper we examine the data rate control effects on the working of cognitive radio adhoc n...

In the square-root Nyquist transmit-filtered single-carrier (SC) transmission, increasing the roll-off factor can reduce the peak-to-average power ratio (PAPR) of the transmit signal. Furthermore, since the signal bandwidth becomes wider, larger frequency diversity gain can be achieved. In our previous work, we proposed joint minimum mean square error frequency-domain equalization (MMSE-FDE) & ...

In cognitive radio communication, unlicensed secondary user (SU) can access underutilized spectrum of the licensed primary user (PU) opportunistically for emerging wireless applications. With interweave implementation, SU has to perform spectrum sensing on the target frequency band and waits for transmission if PU occupies the channel. This waiting time results in extra delay for secondary tran...

We measure the transmission spectrum of WASP-19b from three transits using low-resolution optical spectroscopy from the Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS). The STIS spectra cover a wavelength range of 0.29–1.03 μm, with resolving power R = 500. The optical data are combined with archival near-infrared data from the HST Wide Field Camera 3 (WFC3) G141 grism,...

In practice, radio spectrums allocated to cellular networks are usually underutilized. To increase the spectrum usage efficiency, we studied spectrum sharing between a cellular uplink and a mobile ad hoc networks. These networks use either all uplink frequency sub-channels or their disjoint sub-sets, called spectrum underlay and spectrum overlay, respectively. Given these methods, the capacity ...

The scarcity of spectrum is increasing day by day due to the spectrum scarcity faced by the wireless based service providers led to high congestion levels. The main reason that leads to inefficient utilization of the radio spectrum is the spectrum licensing system itself. Due to this static and rigid allocation, wireless systems have to work only on a dedicated band of spectrum and cannot chang...

This paper proposes a transmission capacity model with an overlaid regime that models the cognitive radio technology. We study a case of two coexisting wireless networks (the primary (PR) network and the secondary (SR) network) operating in the same geographical region and sharing the same spectrum and define the transmission capacity as a product of three signal propagation parameters: the den...