The direct sequence (DS) spread spectrum communication technique is widely regarded as one of the most effective methods of mitigating the effects of a repeating jammer in military communications systems. The proposed system coupled DS with multiple frequency shift keying (DS/MFSK). It is comprised of a transmitter and a receiver. Non-coherent demodulation is examined, as are the spreading sequences in question. The effect of AWGN and Rayleigh fading channels on the proposed approach's bit error rate (BER) is examined. The investigation demonstrates that even with an 8 dB signal-to-noise ratio, superior outcomes can be achieved; this study's suggested endeavor is to create a novel transceiver system built on the DS/MFSK modular architecture. MFSK modulation prevents multiple-access interference, while DS is typically employed to boost system efficiency across erratic fading. Test results show that reliability on the AWGN channel decreases a little while reliability is greatly enhanced by Rayleigh fading. Moreover, notable improvements in bandwidth efficiency are achieved.
Serial Concatenation Convolutional Codes (SCCCs) encoder is built using a serial concatenation of two Recursive Systematic Convolutional (RSC) encoders, separated by an interleaver. These two RSC encoders depending on the trellis termination criteria are software implemented and the performance of each one of them is analyzed under different conditions and circumstances. The output data from the encoder are multiplied by an amplitude matrix (AM) at the transmitter side and the Inverse of Amplitude Matrix (IAM) at the receiver side. The reliability estimation, log-likelihood algebra, and soft channel outputs for Soft Output Viterbi Algorithm (SOVA) are examined. Then the modified Viterbi metric that incorporates a-priori information used for SOVA decoding is derived. A low memory implementation of the SOVA decoder is presented. The iterative SOVA for SCCCs is described with illustrative examples. The behavior of the SCCCs encoder-decoder scheme is tested under different circumstances with AM and without AM at the AWGN and Rayleigh fading channels with unlike frame sizes (FS) and constraint length (K). The results show that the performance of system with AM outperforms the other conventional system that worked without AM.
Designing an integrated communications system with efficient features is important to researchers and designers. This paper deals with a review of the most important technologies and applications that combine solar cells and communication systems such as Li-Fi technology and its principle of operation, which is a wireless system in which the optical signal is used as a carrier signal as an alternative to the traditional radio frequencies used in Wi-Fi networks, where Li-Fi relies on LED to transmit data, and at high speeds that exceed Wi-Fi technology. Solar Power Satellite (SPS) technology where the satellite is placed in a geostationary orbit in the equatorial plane. As well as the application of photovoltaic solar cells in the SOLPLANT planar antenna, and the replacement of the radiating element of the antenna with a solar cell. The solar cell can transmit and receive electromagnetic signals as well as generate direct current and can be used as antennas either as a single solar cell or group cells and has wide applications in wireless, mobile, Bluetooth and satellite systems. The solar cell has also been applied in Micro strip antenna called Solan , where the solar cell antenna can be considered as a platform for many communication applications and can also be adopted as a radio frequency transmitter and receiver. As well as the design of many antennas integrated with solar cells and compatible with the 5G communication system , in addition to the presence of many applications that combined smart phones and solar cells. This study showed that these technologies and applications provided clean, safe, high-efficiency, high-speed, data-transferring communication systems with low cost.
In this paper, a proposed structure was suggested by replacing the blocks of the fast Haar Wavelet Transform (WT) with a two dimensional wavelet transform at the transmitter and the receiver sides in the Orthogonal Frequency Division Multiplexing (OFDM) model. This can be done by converting a 1-Dimensional vector into a 2-Dimensional matrix and process it by 2-Dimensional Wavelet Transform (2D-WT). The proposed method was applied on the OFDM in Additive White Gaussian Noise (AWGN) and flat fading channel. It was concluded that the proposed method gives much better Bit Error Rate (BER) performance than the conventional OFDM model based on WT. The simulation results showed that the proposd structure outperforms the other scheme in the carried tests at the AWGN and flat fading channels.