Explore the vast range of titles available.

Free-space optical (FSO) communication system provides several advantages over radio frequency (RF) system offering high bandwidth, low cost, small space requirements and more secure transmission which is free from Electromagnetic Interference (EMI). However, when the transmitted light signal passes through the atmosphere it experiences attenuation and fluctuations due to atmospheric turbulence. This paper analyzes the bit error rate (BER) performance of FSO communication systems under strong atmospheric turbulence for on-off keying (OOK), binary phase-shift keying (BPSK), differential phase shift keying (DPSK), quadrature phase shift keying (QPSK) and 8-phase shift keying (8-PSK) for link distances of 500, 1,000, 1,500 and 2,000 m. The probability density function (pdf) of the received irradiance is modelled using the gamma-gamma distribution model. It is found that the system exhibits the best BER performance and compensates the lowest power penalty at BER of 10 for BPSK modulation compared with other modulation techniques which makes BPSK more appropriate to be used with FSO turbulent system.

Time‐domain all‐digital‐phase‐locked‐loop phase‐shift‐keying (PSK) demodulators are proposed for BPSK, QPSK, and 8PSK signals. The demodulator architectures are highly suitable for low‐voltage nanoscale CMOS techology. Data‐bit extraction as well as phase control for loop locking can be effectively achieved in a time domain with simple logic operators such as positive‐edge‐trigger RESET/SET (pRSFF) and delay flip flops (DFF). Pulse width of the phase‐control signal is sampled and passed on to the digitally‐controlled oscillator (DCO) for frequency and phase adjustment. Two different phase control methods have been employed to appropriately alter a duty cycle of the phase‐control signal. The first option is performed by multiplexing a single‐phase DCO signal as selected by the extracted data bits. The second technique uses m DCO phases simultaneously for phase‐control detection with the incoming m ‐PSK signal. This helps reduce the intertwined loop of the first method to a single‐loop structure. This modular BPSK, QPSK, and 8PSK demodulation concept has been successfully verified by measurement with discrete components at a carrier frequency of 100 kHz operating under a 5‐V supply.

This research aims to analyze the effects of different parameter estimation on the recognition performance of satellite modulation signals based on deep learning (DL) under low signal to noise ratio (SNR) or channel non-ideal conditions. In this study, first, the common characteristics of broadband satellite modulation signal and the commonly used signal feature extraction algorithm are introduced. Then, the broadband satellite modulation signal pattern recognition model based on deformable convolutional neural networks (DCNN) is built, and the broadband satellite signal simulation is conducted based on Matlab software. Next, the signal characteristics of binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), 8 phase shift keying (PSK), 16 quadratic amplitude modulation (QAM), 64QAM, and 32 absolute phase shift keying (APSK) are extracted by the constellation map, and the ratio changes of T1 and T2 with SNR are compared. When SNR is given, it is compared with VGG model, AlexNet model, and ResNe model. The results show that the constellation points of satellite signals with different modulations are evenly distributed. T1 of PSK modulation signals increases significantly with the increase of SNR. When SNR is greater than 10, PSK modulation signals can be identified. When T2 is set and SNR is greater than 15dB, 16QAM and 32APSK signals can be distinguished. In the model, the Relu activation function, mini-batch gradient descent (MBGD) algorithm, and Softmax classifier have the best recognition accuracy. PSK modulation signals have the best recognition rate when the SNR is 0dB, and the recognition accuracy of different modulation signals at 20dB is over 98%. When the data length reaches 4000, the recognition accuracy of different modulation signals is higher than 97%. Compared with other algorithms, this algorithm has the highest recognition accuracy (99.83%) and shorter training time (3960s). In conclusion, the broadband satellite modulation signal pattern recognition algorithm of DCNN constructed in this study can effectively identify the patterns of different modulation signals.

Ensuring the security and privacy of confidential data during transmission is a critical challenge, necessitating advanced techniques to protect against unwarranted disclosures. Steganography, a concealment technique, enables secret information to be embedded in seemingly harmless carriers such as images, audio, and video. This work proposes two secure audio steganography models based on the least significant bit (LSB) and discrete wavelet transform (DWT) techniques for concealing different types of multimedia data (i.e., text, image, and audio) in audio files, representing an enhancement of current research that tends to focus on embedding a single type of multimedia data. The first model (secured model (1)) focuses on high embedding capacity, while the second model (secured model (2)) focuses on improved security. The performance of the two proposed secure models was tested under various conditions. The models’ robustness was greatly enhanced using convolutional encoding with binary phase shift keying (BPSK). Experimental results indicated that the correlation coefficient (Cr) of the extracted secret audio in secured model (1) increased by 18.88% and by 16.18% in secured model (2) compared to existing methods. In addition, the Cr of the extracted secret image in secured model (1) was improved by 0.1% compared to existing methods. The peak signal-to-noise ratio (PSNR) of the steganography audio of secured model (1) was improved by 49.95% and 14.44% compared to secured model (2) and previous work, respectively. Furthermore, both models were evaluated in an orthogonal frequency division multiplexing (OFDM) system over various wireless channels, i.e., Additive White Gaussian Noise (AWGN), fading, and SUI-6 channels. In order to enhance the system performance, OFDM was combined with differential phase shift keying (DPSK) modulation and convolutional coding. The results demonstrate that secured model (1) is highly immune to noise generated by wireless channels and is the optimum technique for secure audio steganography on noisy communication channels.

In this article, a multifunctional optical processing unit for differential eight phase‐shift‐keying (D8PSK) and differential quadrature phase‐shift‐keying (DQPSK) based on four‐wave mixing (FWM) effects in semiconductor optical amplifier (SOA) is proposed. All‐optical wavelength conversion, D8PSK‐to‐DQPSK format conversion and signal encryption of 10‐Gbaud DQPSK and D8PSK optical signals are achieved simultaneously by simulation. Detailed theoretical analysis and simulation results are conducted to verify the feasibility of the scheme. The Q factor of the electrical signals and the bit error rate recovered from wavelength and format converted components are approximated to be around 6, and 10−9, which indicates the feasibility of the scheme. For the encrypted signal, the FWM effect of another SOA is utilized to decrypt the encrypted signal, and the encryption function of 10‐Gbaud DQPSK and D8PSK optical signals is also verified. All‐optical wavelength conversion, D8PSK to DQPSK format conversion and signal encryption of 10‐Gbaud DQPSK and D8PSK optical signals are achieved simultaneously by using a SOA‐FWM‐based multifunctional optical switching unit. Detailed theoretical analysis and simulation results are conducted to verify the feasibility of the scheme.

Graphene-based photodetectors have attracted significant attention for high-speed optical communication due to their large bandwidth, compact footprint, and compatibility with silicon-based photonics platform. Large-bandwidth silicon-based optical coherent receivers are crucial elements for large-capacity optical communication networks with advanced modulation formats. Here, we propose and experimentally demonstrate an integrated optical coherent receiver based on a 90-degree optical hybrid and graphene-on-plasmonic slot waveguide photodetectors, featuring a compact footprint and a large bandwidth far exceeding 67 GHz. Combined with the balanced detection, 90 Gbit/s binary phase-shift keying signal is received with a promoted signal-to-noise ratio. Moreover, receptions of 200 Gbit/s quadrature phase-shift keying and 240 Gbit/s 16 quadrature amplitude modulation signals on a single-polarization carrier are realized with a low additional power consumption below 14 fJ/bit. This graphene-based optical coherent receiver will promise potential applications in 400-Gigabit Ethernet and 800-Gigabit Ethernet technology, paving another route for future high-speed coherent optical communication networks. Graphene-based photodetectors have many advantages for applications. Here, the authors demonstrate a high-speed optical coherent receiver for optical communications based on graphene-on-plasmonic slot waveguide photodetectors.

Due to the mobility of subjects carrying wireless Body Area Networks (WBANs), a BAN may be found in an environment that contains other adjacent BANs, which may influence its proper functioning. The purpose of this paper is to study the effect of interference between adjacent BANs on the performance of a reference BAN in terms of packet loss rate (PLR), while considering the following four parameters: the distance separating adjacent BANs, the number of nodes and traffic payload of an interferer BAN, and the transmission data rate. The study is conducted for the two modulation schemes proposed by the IEEE 802.15.6 standard in the 2.4 GHz narrow band, which are: Differential Binary Phase Shift Keying (DBPSK) modulation and Differential Quadrature Phase Shift Keying (DQPSK) modulation. Simulation results have shown that the adoption of a lower-order modulation such as DBPSK can reduce the effect of interference among adjacent BANs.

Existing single-channel orthogonal frequency division multiplexing (OFDM) system can transmit data from single source to single destination occupying the entire link but bit error rate (BER) provided by these systems is quite high. The multichannel system gives the liberty to route the traffic through the different channels depending upon the availability. So there is a need to design a multichannel system which can transmit the data at higher rate by transmitting multiple symbols simultaneously with improved BER. So, in this research work, we propose a multichannel OFDM system by using an advanced modulation technique, i. e. quadrature amplitude modulation which not only improves the capacity but also makes the system power efficient. In order to demonstrate that our proposed system is power efficient, a set of simulations have been performed. Results show that BER (as a function of power) obtained for the proposed system is low in comparison to the already existed phase shifting keying- and differential phase shift keying-based system.

ABSTRACT This paper offers the different type transmission schemes used in wireless sensor networks. The wireless sensor network used in a number of applications such as Agriculture, Military, Medical, Multimedia etc. According to the applications there are different quality of service parameters and designing requirements for different layers in network design. While designing any ad hoc network or sensor network many designing principals and challenges are taken into consideration. For the designing of protocols layering in ad hoc sensor network basically a five layer model is taken into consideration. These layers are application, transport, network, Medium access control and physical layer. In this paper different types of designing constraints associated with physical and medium access layer has been introduced for different applications in sensor networks. In that manner this paper helps us to select the designing of a link for particular application.

In this paper, the performance of dual-hop relay transmission in modern wireless communication systems is analyzed by considering two fundamental relaying techniques, namely, Amplify-and-Forward (AF) and Decode-and-Forward (DF). The propagation conditions on the source–relay (S-R) and relay–destination (R-D) links are modeled using the κ-μ statistical distribution, which effectively captures the fading characteristics in both line-of-sight (LoS) and non-line-of-sight (NLoS) environments. The analysis focuses on key performance metrics, including the outage probability (Pout) and average bit error probability (Pe), for Binary Phase Shift Keying (BPSK) and Quadrature Phase Shift Keying (QPSK) modulation schemes, assuming transmission via a single relay without a direct S–D link. Closed-form expressions for the considered metrics are derived based on the κ-μ model and verified by numerical evaluation. In addition to classical analytical modeling, a Generative Artificial Intelligence (GenAI)-enabled workflow is incorporated as a supportive tool in order to aid in automated analysis, the interpretation of the results in the context of network management under varying channel and system parameters based on the Pout and Pe calculations with the aim to tackle the underlying complexity and cognitive load of infrastructure adaptation and re-configuration operations. The combined analytical and GenAI-assisted approach provides valuable insights for the optimization, design, and continuous evolution of robust relay-based architectures in next-generation wireless networks.