While the amplitude, frequency and phase, are the well-known carrier features that can be modulated according to digital data stream, there is still another unexploited sinusoidal feature. Sinusoidal damping factor is the suggested modulation technique that can be used in carrier communication. In this paper, damping shift keying (DSK) is proposed as a new modulation space that can be combined with conventional modulation techniques to increase the data rate per symbol. In addition to the complex amplitude modulation, the carrier can be modulated using multi-damping factors according to the data stream. Combination of DSK with quadrature amplitude modulation (QAM) increases the data rate of the so called Damped QAM (D-QAM). Simulation results measures the performance of the proposed D-4PSK (carrying 3 bits/symbol) against conventional QPSK (carrying 2 bits/symbol). The proposed scheme …

Single tone M-ary frequency shift keying (MFSK) enjoys constant envelop transmission at the expense of much lower spectral efficiency (SE). Many research efforts were given for enhancing the SE of MFSK. In this paper, SE of coherent single tone MFSK is improved by filling up the same allocated spectral band-width by larger number of uniformly spaced non-orthogonal tones. The main idea resides in two main points, first, regarding the detection task as an operation of super-resolution (SR) spectral line estimation, second, highlighting implicit sparsity construction of MFSK scheme. Compressive sensing (CS) based SR approaches are enabled for resolving activated atom from over-complete dictionary. Moreover, more general keying schemes can be performed on learned dictionary instead of the classical Fourier (sinusoidal) dictionary, where each atom may occupy the whole allocated spectrum instead of …

Jointly enhancing both energy efficiency (EE) and spectrum efficiency (SE) of modulation schemes becomes one of the main issues for 5G mobile communications. Recently, an indexed modulation (IM) technique provides an interesting tradeoff between EE and SE. Data can be conveyed through the combination of subcarriers pattern that can be divided between activated/non-activated subcarriers in the frequency domain. Maximum SE can be attained at half subcarrier activation, hence producing symbols with half energy of the conventional orthogonal frequency-division multiplexing (OFDM) system. In this paper, alternatively, the new concept of sparsely indexing modulation (SIM) on overall subcarrier space is clarified. Sparse (few) subcarrier activations provide much higher EE, while the combinatorial indexing of the sparse subcarriers on the overall subcarriers as a single group spans huge combinatorial …

In this paper, sparse activated subcarriers OFDM index modulation (SAS-OFDM-IM) and interpolated sparse activated subcarriers OFDM index modulation (ISAS-OFDM-IM) are proposed to improve the spectrum efficiency of OFDM modulation technique in visible light communication (VLC) systems. To be suitable for intensity modulation (IMod) by Light Emitting Diode (LED) used in VLC systems, the Unipolar Orthogonal Frequency Division Multiplexing (U-OFDM) is used. U-OFDM is more power efficient in an Additive White Gaussian Noise (AWGN) channel, which is prevalent in an optical wireless system. At the receiver, threshold detector has been used for detecting the activated subcarriers by taking the highest K out of N, where N is the total number of OFDM subcarriers and K is the total number of activated subcarriers. Results indicate that, using the proposed schemes can improve both the spectral efficiency …

Cognitive Radio Networks have been proposed as a promising solution for the spectrum deficiency problem. Even though, because of the opportunistic access and heterogeneity nature of these networks, they are exposed to threats such as the presence of jammer which aims to jeopardize the network transmissions. In this article, we introduce an anti-jamming cooperative framework to mitigate or minimize the impact of the jammer on the cognitive radio network. In the proposed solution, the secondary coordinator distributes the Secondary Users (SU) over the selected channel and pairs the SUs to form cooperative coalitions which utilize cooperative transmission to establish more robust transmission links to overcome the effect of the jammer power. Stackelberg game is used to model the interaction between the jammer and the network coordinator. The outcomes show the superiority of using cooperative transmission over the traditional direct transmission. Also, the performance of the secondary network enhances as the number of SUs increases due to the higher probability of forming cooperative groups. © Springer Nature Switzerland AG 2020.

Limitations of using the radio spectrum have risen because of the increasing demand for wireless communication services. However, as a large portion of the Primary User’s (PU) spectrum is not effectively utilized because of assignment a fixed spectrum; the Cognitive Radio (CR) approach is considered as a solution, which enables the best access to the available spectrum. Spectrum sensing detects the temporarily unused frequency bands across the PU radio spectrum. In this paper, a novel approach for improving the spectrum sensing in the cognitive radio network is proposed for a network consists of a Primary User (PU), Secondary Users (SUs), and single Fusion Center (FC). The proposed approach is achieved by forming a centralized cooperation sensing among cognitive radio users in the noisy environment. All SUs use the energy detection as a sensing technique, and then the result will be sent to FC to …

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In the study, the effect of nano ferric oxide (Fe2O3) modification was investigated to improve the rheological properties of bitumen and mechanical properties of Hot Mix Asphalt (HMA). Rutting potential and non-recoverable compliance (Jnr) were determined after subjecting modified bitumen to short-term and long-term aging. Multiple Stress Creep Recovery (MSCR) test was conducted to evaluate Jnr of bitumen and performance grade. Low temperature stiffness and flexural properties of modified bitumen were also determined. Indirect Tensile Strength (ITS) and Tensile Strength Ratio (TSR) of HMA modified with nano Fe2O3 was determined. Rutting was also determined by Hamburg Wheel Tracking Device (HWTD) for HMA modified with nano Fe2O3. Solar reflection was measured on HMA modified with nano Fe2O3. Results showed that, the nano Fe2O3 improved the rutting potential and non-recoverable compliance. Maximum rutting performance was observed by 5% Fe2O3 modified bitumen. The non-recoverable compliance and the rutting resistance have related. Modified HMA samples have higher strength value than reference sample. Nano Fe2O3 modification of HMA was provided resistance against moisture damage. 1% Fe2O3 modified HMA has the highest rutting resistance with the maximum 6 mm rut depth. Heat islands were increased by nano Fe2O3 modification.

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