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In this work, to overcome the flaws of standard chaotic maps we generated two new cascaded structures, 3D Cubic-Sine and 2D Cubic-Cat chaotic parametric maps, based on a new parameter-varied Cubic map that enhance the chaos complexity and therefore offering a high randomness’s level of the chaotic sequences and a huge key space.To provide optimum security for image transmission, we introduce several methods with a new approaches in Stenography and encryption of quadrature amplitude modulation symbols (QAM)based on the new maps, all in a purpose of enhancement physical layer security. Some of the best results obtained are: the peak signal-to-noise ratio (PSNR) values of 96.2956 dB, 88.767 dB, 78.1094 dB respectively with the three methods, also the entropy of encrypted image reaching much closely the ideal value, being 8 ≈ 7.9999868, strong resistance against differential attack with Number of Pixels Change Rate (NPCR) of 99.63%, Unified Average Changing Intensity (UACI) of 33.54% and high speed ciphering based on 3D Cubic-Sine noise encryption time of 0.024s.The experimental results indicate that these new maps outperforms the most competitive recently proposed maps in multimedia cryptosystems.

In order to furnish connectivity to an incredible number of devices and to satisfy the capacity demands, non-orthogonal multiple access (NOMA) is considered as a hopeful solution for future 5G. Moreover, grant-free transmission is substantially expected in the uplink NOMA to minimize the latency time and detection overhead. However, multi-user detection (MUD) without user-activity information in uplink grant-free NOMA is hard in practice. In this paper, by benefit from the user-activity sparsity existing in uplink grant-free NOMA, the multipath matching pursuit (MMP) is used for user-activity detection, and then message passing algorithm (MPA) can be efficiently applied for active users’ data detection. Simulation results show that the proposed MMP-MAP MUD with acceptable complexity can achieve better performance than conventional solutions. Also, the MMP-MAP detector reaches the performance obtained by the MPA detector with perfect user-activity information once the level of signal-to-noise ratio exceed 11 dB.

This letter demonstrates the chaotic precoding approach in multiple-input multiple-output space frequency block coded orthogonal frequency division multiplexing (MIMO SFBC-OFDM) communication syste...

This paper deals with the Peak to Average Power Ratio (PAPR) drawback appeared in Filter-Bank Multi-Carriers with Offset-QAM (FBMC-OQAM) which is the candidate waveform in 5G wireless communication systems. A post-Inverse Discrete Fourier Transform (IDFT) Discrete Sliding Norm Transform (DSNT) is proposed based on L2-metric and the norm of five samples at each sliding operation. The overlapping structure of FBMC-OQAM is considered in the proposed L2-by-5 DSNT formulation. It can significantly reduce the PAPR in FBMC-OQAM systems, which ensures a linear amplification at the High Power Amplifier (HPA) and avoids signal distortion. The main advantages of this technique are its lower computational complexity compared to the known techniques, and the fact that it does not require any Side Information (SI) at the receiver. Simulation results show that the L2-by-5 DSNT technique can achieve an improvement of 40% in PAPR reduction at CCDF = 10–3 compared to the original FBMC-OQAM system.

Ultra−WideBand (UWB) technology was approved by the Federal Communications Commission (FCC) in February 2002 (FCC, 2002). According to the FCC regulations, the frequency band from 3.1 to 10.6 GHz can be used for short−range and high speed wireless communications systems. This recent allocation of a very wide spectrum of frequencies for the devices uses, with effective isotropic radiated power (EIRP) less than 41dBm/MHz has presented numerous exciting opportunities and challenges for antenna designers. UWB antennas should be effective in transmitting, compact, non dispersive, and have a good wide impedance bandwidth properties, these features are desirable for both indoor and outdoor hand−held UWB applications. In practical UWB applications, microstrip antennas that can be directly printed onto printed circuit boards (PCBs) are the most promising candidates. Such a PCB antenna has a low profile, a low manufacturing cost and can easily be integrated with other parts of monolithic microwave integrate circuit (MMIC) for a transceiver or any other UWB system. To satisfy such requirements, various types of planar antennas have been developed for UWB communications over the last few years. Also, several bandwidth enhancement techniques have been reported, to improve the impedance bandwidth of these antennas. Microstrip UWB antennas are usually constructed by etching a radiator onto the dielectric substrate of a piece of the PCB and a partial ground plane onto the opposite side if the antenna is fed by microstrip transmission line or on the same side in the case of coplanar waveguide (CPW) feeding. In the literature, many different microstrip UWB antennas with circular, elliptical, triangular, rectangular, hexagonal, and so on patches are currently being considered for UWB applications. This chapter presents an overview of UWB antennas design an characterization, some novel designs were investigated and presented. The first class of studied UWB antennas is microstrip monopole antennas including the microstrip/CPW−fed modified − elliptical monopole antennas. The second class is for UWB slot antennas, where a novel stepped inverted cone slot antenna with different stub shapes is proposed for UWB applications. In the third class a notched band UWB antenna is presented; the proposed UWB have been developed to notch−band UWB antenna by inserting a U−shape slot into patch. The advantage of this approach is that the stop−band filter (slot) can directly integrated in antenna structure. The study includes detailed parametric analysis of the antennas performances with relation to the desirable properties for UWB antennas. 15

Multimedia content delivery applications over wireless sensor networks have been progressively popular. The crucial obstacle to communicating compressed images over wireless multimedia sensor networks (WMSNs) has been the lack of suitable energy efficient processing architectures and strategies. In this letter, we propose a low-complexity energy efficient scheme to improve the transmission quality of images compressed by the embedded zerotrees of wavelet transforms and set partitioning in hierarchical trees algorithms in the WMSNs based on an orthogonal frequency-division multiplexing technique. The proposed scheme use a simple post-inverse discrete Fourier transform modified $\mu $ nonlinear transformation, called $\mu $ -MNLT. Simulation results show the effectiveness of the proposed approach, which gives an improvement of peak signal-to-noise ratio (SNR) of about 30 dB (at SNR = 8 dB) without any bit-error-ratio degradation.

This paper is aimed at proposing a novel printed microstrip-fed slot antenna suitable for wireless ultra-wideband (UWB) communication systems. The proposed antenna has been designed for operating at GHz frequency band. The synthesis of the antenna is carried out by means of parametric study of the main parameters. The result is a printed stepped-circular-shaped slot antenna exhibiting a good impedance matching with different tuning stubs. To demonstrate the effectiveness of the proposed UWB antenna, the results from numerical validations and experimental tests are presented and discussed.

In this paper we present an analytical probability density function (PDF) for the multiuser interference (MUI) in a transmitted-reference ultra-wideband (TR-UWB) communication system. We show that the Middleton class-A model is a more appropriate statistical model for the MUI than the generally used Gaussian approximation (GA). Also, we derive a PDF of the sum of MUI, Gaussian noise and symmetric-α-stable (SαS) interference. The proposed closed-form PDF for the overall noise enjoys a good fitness to develop improved TR-UWB receiver structures which can perform better in multiple access environments with impulsive interference.