Summary Long‐term evolution (LTE) system adopts single‐carrier frequency division multiple access (SC‐FDMA) technique for high data‐rate uplink wireless communication mainly due to its advantage of high power efficiency and low peak‐to‐average‐power ratio (PAPR). This paper presents a chaotic interleaving scheme for the discrete wavelet transform‐based SC‐FDMA (DWT SC‐FDMA) system to improve the transmission quality of images. This interleaving process is‐ based on applying the chaotic Baker map to the image before transmission. The proposed scheme combines the advantages of excellent orthogonality and spectral containment from DWT SC‐FDMA and performances enhancement from chaotic interleaving. The performances evaluation of the DWT‐SC‐FDMA system with the chaotic interleaving scheme for efficient image transmission is studied and compared with two schemes of SC‐FDMA‐based systems: discrete Fourier transform SC‐FDMA (DFT SC‐FDMA) and discrete cosine transform SC‐FDMA (DCT SC‐FDMA) over different wireless channel and subcarriers mapping modes. This comparison aims to select the most suitable structure of SC‐FDMA for the efficient transmission of the images. The obtained results demonstrate the efficiency of the proposed scheme, which gives an improvement of peak signal‐to‐noise ratio (PSNR) of about 36 dB (at SNR = 8 dB) is the case of SUI‐3 channel and a significant enhancement in bit‐error‐ratio (BER) performance.
Summary ECMA‐368 Standard adopts multiband orthogonal frequency division multiplexing (MB‐OFDM) for high rate ultra‐wideband (UWB) communication systems as a possible candidate for indoor wireless personnel area networks. One of the main drawbacks of MB‐OFDM modulation is the high peak‐to‐average power ratio (PAPR), which limits the power efficiency of the digital‐to‐analog converter and the high power amplifier due to nonlinear distortion. In this paper, a post inverse discrete Fourier transform nonlinear transformation called parametric discrete sliding norm transform (PDSNT) is proposed to reduce the PAPR in MB‐OFDM systems. The PDSNT method in addition to its much lower computational complexity than other schemes recently proposed for ECMA‐368 UWB systems introduces an efficient controlling parameter to obtain a good tradeoff between PAPR reduction and bit error rate (BER) performance degradation. Simulation results show that the proposed PDSNT‐based MB‐OFDM scheme can achieve better performance in PAPR reduction than conventional solutions with affordable BER performance degradation in UWB channel models.
A multiple-input-multiple-output (MIMO) ultra-wideband (UWB ) printed bent antenna, suitable for MB-OFDM ECMA-368 system integration with the wireless universal serial-bus (WUSB) dongle is proposed. The antenna consists of two antenna elements with an overall area of 18 X 53 mm2. Each antenna element is a simple modified folded-monopole fed by a coplanar waveguide (CPW). The design process of proposed MIMO UWB CPW-fed bent antenna configuration is presented in four simple steps. Experimental results show that the proposed design has a good impedance bandwidth in the range of 2.95–18.55 GHz with 147.2% fractional bandwidth (FBW). Moreover, the proposed antenna enjoys, low envelope correlation coefficient (ECC), good diversity gain (DG), low total active reflection coefficient (TARC) and omnidirectional radiation patterns. The bit error rate (BER) of the overall MB-OFDM ECMA-368 system with the existence of the proposed MIMO UWB CPW-fed bent antenna is evaluated in more realistic transmission channel scenario by using the extracted transmitting and receiving UWB antennas transfer functions.
The single-carrier frequency division multiple access (SC-FDMA) is a promising technique that has been adopted as an uplink transmission scheme in the long-term evolution (LTE) cellular system. This is attributed to its advantages such as the low peak-to-average power ratio (PAPR) and the utilization of frequency-domain equalizers to resolve the problem of inter-symbol interference (ISI). In this paper, a Discrete Wavelet Transform (DWT) based SC-FDMA system is proposed for the effective transmission of encrypted images. The 2D Chaotic baker map encryption algorithm has been used to encrypt images to enhance their security during transmission via SC-FDMA- based systems. The performance of the process of encrypted image transmission using the 2D Chaotic baker map algorithm with wavelet transform-based SC-FDMA (DWT SC-FDMA) system is evaluated in terms of different performance metrics, with comparison to Discrete Fourier Transform SC-FDMA (DFT SC-FDMA) and, Discrete Cosine Transform SC-FDMA (DCT SC-FDMA) systems. The viability of the proposed scheme was tested with different wireless channel models and different subcarriers mapping schemes. Experimental results show that the proposed method of the encrypted image transmission via the DWT SC-FDMA system provides a remarkable performance gain compared to the other versions of the SC-FDMA system in terms of the PSNR, and the BER metrics in the wireless channel models. It also demonstrates the effectiveness of the proposed scheme and adds a degree of encryption to the transmitted images through the wireless channels.
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