Design Of Communication Systems Research Articles

Investigation of Doppler Frequency Shift Effect on the Performance of Four-Channel Space Chaotic Laser Communication

In this article, the wavelength division multiplexing (WDM) technology is applied to the space chaotic laser communication system. We deduce the bit error rate (BER) model of multi-channel space chaotic laser communication with Doppler frequency shift. Based on the BER model, the effect of Doppler frequency shift on the performance of four-channel space chaotic laser communication systems on the synchronous orbit(GEO)-low earth orbit(LEO) and GEO-mid earth orbit(MEO) has been discussed in detail. The numerical simulation results indicate that the effect of Doppler frequency shift on GEO-LEO system is much less than GEO-MEO system. Therefore, the Doppler frequency shift effect of GEO-LEO system can be overcome by redundant design, and the Doppler frequency shift effect of GEO-MEO system must be paid more attention to the optimum design. Besides, the relationship between the performance of communication system and frequency shift under different channels are similar. The result has an important implication for reducing the complexity of the system design. These results of the article are significant for the design of the four-channel space chaotic laser communication system.

Optimized Design for IRS-Assisted Integrated Sensing and Communication Systems in Clutter Environments

In this paper, we investigate an intelligent reflecting surface (IRS)-assisted integrated sensing and communication (ISAC) system design in a clutter environment. Assisted by an IRS equipped with a uniform planar array (UPA), a multi-antenna base station (BS) is targeted for simultaneously sensing multiple targets in the non-light-of-sight (NLoS) region and communicating with multiple communication users (CUs). We consider the joint IRS-assisted ISAC design in the case with Type-I or Type-II CUs, where each Type-I CU and Type-II CU can and cannot cancel the interference from sensing signals, respectively. Under the perfect communication/sensing channel state information assumption, we aim to maximize the minimum sensing beampattern gain among multiple targets, where the sensing beampattern gain qualifies the achieved illumination signal power at the given location of the target of interest. We jointly optimize the BS’s communication-sensing beamformers and the IRS’s phase shifting matrix, subject to the signal-to-interference-plus-noise ratio (SINR) constraint for each Type-I/Type-II CU, the interference power constraint per clutter, the transmission power constraint at the BS, and the cross-correlation pattern constraint. Due to the design variable coupling, the joint IRS-assisted ISAC design problem is shown to be non-convex in the case with Type-I or Type-II CUs. To circumvent the non-convexity dilemma, we propose semidefinite relaxation (SDR) based alternating optimization algorithms in both cases, for which the computational complexity and convergency behavior are analyzed. In the case with Type-I CUs, we show that the dedicated sensing signal at the BS can help enhance the sensing performance gain. By contrast, the dedicated sensing signal at the BS is not required for the IRS-assisted ISAC designs in the case with Type-II CUs. Numerical results are provided to show that the proposed IRS-assisted ISAC design schemes achieve a significant gain over the existing benchmark schemes.

Wireless Sensor Network-based Monitoring System for Health Structure of Rail-tracks: An Efficient Design for Communication

The paper introduces a monitoring system for the health structure of rail-tracks. The slab track system is highly demanded due to its quality for safety measures and highly sustainable quality for high-speed railway infrastructure, particularly in India for the Bullet-train project. Previously, the system used to monitor the health of slab-tracks was costly and not done regularly, but the evolution of digitalization and wireless sensor networks is doing tremendous work for monitoring the health of infrastructure and other activities. In rail-track systems, wireless sensors can provide us with information, detection, and prediction of the health-infrastructure of rail-tracks. An efficient design for communication systems is needed for such safety-critical railway tracks. The paper proposes an accurate and efficient design for communication.

Molecular Absorption Effect: A Double-Edged Sword of Terahertz Communications

Communications in the terahertz band (THz) (0.1- 10 THz) have been regarded as a promising technology for future 6G and beyond wireless systems, to overcome the challenges of evergrowing wireless data traffic and crowded spectrum. As the frequency increases from the microwave band to the THz band, new spectrum features pose unprecedented challenges to wireless communication system design. The molecular absorption effect is one of the new THz spectrum properties, which enlarges the path loss and noise at specific frequencies. This brings in a double-edged sword for THz wireless communication systems. On one hand, from the data rate viewpoint, molecular absorption is detrimental, since it mitigates the received signal power and degrades the channel capacity. On the other hand, it is worth noticing that for wireless security and covertness, the molecular absorption effect can be utilized to safeguard THz communications among users. In this paper, the features of the molecular absorption effect and their impact on the THz system design are analyzed under various scenarios, with the ultimate goal of providing guidelines to how better exploit this unique THz phenomenon. Specifically, since the molecular absorption greatly depends on the propagation medium, different communication scenarios consisting of various media are discussed, including terrestrial, air and space, sea surface and nano-scale communications. Furthermore, two novel molecular absorption enlightened secure and covert communication schemes are presented, where the molecular absorption effect is utilized as the key and unique feature to boost security and covertness.

Shallow Water Experiment of OFDM Underwater Acoustic Communications

The large variability of communication properties of underwater acoustic channels, and especially the strongly varying instantaneous conditions in shallow waters, is a challenge for the designers of underwater acoustic communication (UAC) systems. The use of phase modulated signals does not allow reliable data transmission through such a tough communication channel. However, orthogonal frequency-division multiplexing (OFDM), being a multi-carrier amplitude and phase modulation technique applied successfully in the latest standards of wireless communications, gives the chance of reliable communication with an acceptable error rate. This paper describes communication tests conducted with the use of a laboratory model of an OFDM data transmission system in a shallow water environment in Wdzydze Lake.

Design and simulation of secure fiber optic communication system utilizing hill cipher algorithm

Design and simulation of secure fiber optic communication system utilizing hill cipher algorithm

The Design and Implementation of a Steganographic Communication System over In-Band Acoustical Channels

This article presents SoundSticker, a system for steganographic, in-band data communication over an acoustic channel. In contrast with recent works that hide bits in inaudible frequency bands, SoundSticker embeds hidden bits in the audible sounds, making them more reliably survive audio codecs and bandpass filtering, while achieving a higher data rate and remaining imperceptible to a listener. The key observation behind SoundSticker is that the human ear is less sensitive to the audio phase changes than the frequency and amplitude changes, which leaves us an opportunity to alter the phase of an audio clip to convey hidden information. We take advantage of this opportunity and build an OFDM-based physical layer. To make this PHY-layer design work for a variety of end devices with heterogeneous computation resources, SoundSticker addresses multiple technical challenges including perceivable waveform artifacts caused by the phase-based modulation, bit rate adaptation without channel sounding and real-time preamble detection. Our prototype on both smartphones and ESP32 platforms demonstrates SoundSticker’s superior performance against the state of the arts, while preserving excellent sound quality and remaining unaffected by common audio codecs like MP3 and AAC. Audio clips produced by SoundSticker can be found at https://soundsticker.github.io/ .

Microstrip lowpass-bandpass triplexer with flat channels and low insertion losses: Design and fabrication for multi-service wireless communication systems

In this work, a new basic microstrip structure is proposed and analyzed to obtain a lowpass-bandpass triplexer without any extra matching networks. This is despite the fact that the number of literature on lowpass-bandpass triplexers that have been introduced so far is very low. The lowpass channel cut-off frequency is tuned at 1.85 GHz which makes it appropriate for mid-band 5G and GSM applications. The bandpass channels work at 3.25 GHz and 6.65 GHz for S-band, 5G, WiMAX and C-band applications. The designed triplexer occupies a compact area of 0.021 λg2. In comparison with the previously reported triplexers, the presented triplexer has three low insertion losses of 0.54 dB, 0.16 dB and 0.55 dB. Also, all its channels are flat with three low group delays of 0.79 ns, 0.98 ns and 0.85 ns. For verifying the designing technique and simulation results, we fabricated and measured our triplexer, where all the obtained results are close to each other.

Joint Power Control and Passive Beamforming Design for RIS-Assisted Secure Communication Systems

In this paper, considering the problem of signal blockage in the scenario of dense buildings, we study joint transmit power and phase shift design for the reconfigurable intelligent surface (RIS) assisted secure uplink communication systems. In particular, a friendly user with better channel state information than other users is selected as a jammer to interfere the eavesdropper. We aim to maximize the secrecy rate under the constant-modulus constraint for RIS phase shift. To handle the non-convex problem, we propose an alternating optimization based algorithm, where the successive convex approximation technique and manifold optimization are utilized for the optimization of transmission power and RIS phase shift, respectively. By introduce RIS into this system, the problem of signal blockage is solved. Moreover, simulation results show that the proposed scheme improves the system secrecy rate compared with the other benchmark schemes.

Turbo encoder and decoder chip design and FPGA device analysis for communication system

<p>Turbo codes are error-correcting codes with performance that is close to the Shannon theoretical limit (SHA). The motivation for using turbo codes is that the codes are an appealing mix of a random appearance on the channel and a physically realizable decoding structure. The communication systems have the problem of latency, fast switching, and reliable data transfer. The objective of the research paper is to design and turbo encoder and decoder hardware chip and analyze its performance. Two convolutional codes are concatenated concurrently and detached by an interleaver or permuter in the turbo encoder. The expected data from the channel is interpreted iteratively using the two related decoders. The soft (probabilistic) data about an individual bit of the decoded structure is passed in each cycle from one elementary decoder to the next, and this information is updated regularly. The performance of the chip is also verified using the maximum a posteriori (MAP) method in the decoder chip. The performance of field-programmable gate array (FPGA) hardware is evaluated using hardware and timing parameters extracted from Xilinx ISE 14.7. The parallel concatenation offers a better global rate for the same component code performance, and reduced delay, low hardware complexity, and higher frequency support.</p>

Design of a pulse amplitude modulation-based communication system

The paper presented aims to introduce readers to communication systems that utilize pulse amplitude modulation (PAM) as a means of transmitting data. PAM is a form of modulation that involves varying the amplitude of a series of pulses to represent the information being transmitted. The paper provides a detailed analysis and comparison of various PAM-based communication systems, highlighting their strengths and weaknesses. The main objective of the paper is to offer insights into the design of PAM-based communication systems. By thoroughly examining the different PAM-based communication systems, the authors aim to provide readers with a general understanding of the key considerations involved in designing such systems. The paper concludes with a summary of the main findings and offers some general guidelines that can be applied when designing PAM-based communication systems. Overall, the paper offers a valuable contribution to the field of communication systems, particularly for those looking to design systems that use PAM as their modulation scheme. The insights and guidelines provided in the paper are of reference significance and can be used to inform the design of future PAM-based communication systems.

SIGNAL PROPAGATION

<p style="text-align: justify;">One of the participants that affects the loss of signal quality is propagation. In addition to it, we also have connection attenuation, latency, topology and network design. The quality of the digital signal transmitted from the transmitting to the receiving radio-relay device depends on the influence of environmental effects on the propagation of electromagnetic waves. Signal propagation is defined as path loss when the transmitter and receiver are directly facing each other, and in the event that there are no obstacles present in free space, there is still some signal attenuation. This is decisive for designing communication systems so that they can work despite the problems they may encounter. As the application of local wireless networks grows, so does the need for quality assessment of signal propagation in buildings. The Fresnel zone represents the air space between two transmitters through which radio waves propagate. It has an unlimited number of such zones, but the first three zones are important for signal quality and strength. Most often, only the first zone is counted because it occupies the largest volume and the quality and strength of the signal mostly depends on it. Within these environments, it is extremely important to take into account the types of obstacles and the type of room in which the signal is propagated. As part of this work, there is an overview of the most important propagation models and a review of them.</p>

A deep convolutional-LSTM neural network for signal detection of downlink NOMA system

Non-orthogonal multiple access (NOMA) techniques have drawn much attention for massive connectivity, heterogeneous data traffic with ultra-low latency requirements, and ultra-high bandwidth efficiency for the future generation of wireless communication systems. This paper suggests a deep convolutional-long short-term memory (ConvNet-LSTM) aided receiver for detecting signals in the downlink NOMA system. The proposed technique implicitly estimates channel state information and recovers the transmitted symbol directly. The Bayesian approach optimizes the hyperparameters for the deep ConvNet-LSTM. The proposed learning approach is significantly more efficient than the conventional signal detection method, successive interference cancellation (SIC)-based minimum mean square error (MMSE) technique, other deep learning (DL)-based approaches, long short-term memory (LSTM), and convolutional neural networks (CNNs). It simultaneously explores the characteristics of both spatial and temporal features of the received signal for increasing the detection probability of the system. The simulations discuss the advantages of the deep ConvNet-LSTM-based receiver design for downlink NOMA communication systems in terms of bit error rate (BER), achievable rate, and mean squared error (MSE). Furthermore, the robustness of the proposed deep ConvNet-LSTM approach is evaluated for its superiority to other techniques.

Relay Selection for Dual-Hop Cooperative Ambient Backscatter Communication Systems.

Previous works only focus on the optimization design for the dual-hop cooperative ambient backscatter communication (AmBC) system with single-relay selection. The impact of relay selection on the outage performance of dual-hop cooperative AmBC systems is still missing. Motivated by this, in this paper, we investigate the outage performance of a dual-hop cooperative AmBC system with single-relay selection, where the backscatter link shares the receiver with the cellular link and the harmful direct-link interference (DLI) is mitigated by using successive interference cancellation (SIC). In the system considered, the selected relay has dual functions. One is to forward message for the cellular link, and the other is to act as the radio-frequency (RF) source for the backscatter device (BD). Specifically, after proposing two novel single-relay selection schemes (RSSs), namely reactive RSS and proactive RSS, we derive the closed-form outage probability (OP) expressions for both RSSs, which can be performed in a distributed manner. To gain more insights, the asymptotic OPs at high signal-to-noise ratio (SNR) are explored and the outage performance comparison between the reactive RSS and proactive RSS are also provided. Results show that the proposed reactive RSS is outage-optimal among all possible single-relay selection schemes. The theoretical analysis is validated by Monte Carlo simulations. The results also show that the relay selection scheme, the number of relays, the location of BD, and the reflection coefficient of BD have great impact on the outage performance of cooperative AmBC systems.

Design and Analysis of Analog Feedback Communication System with Rayleigh Fading Channel Model

In this work, we mathematically model a wireless Analog feedback communication system (AFCS) using a Rayleigh fading channel. AFCS system is a new research area and has promising applications, especially in low-power devices such as sensors. Compared to AWGN, Rayleigh fading channel more closely models the real wireless environment. In this work, AFCS Rayleigh fading channel is considered in forward transmission while AWGN is considered in the feedback channel. We evaluated the performance of the system which is mostly based on the minimization of mean square error (MSE) at the receiver. Even in presence of a wireless fading environment, the AFCS attains a 0 MSE value in 2-3 iterations if a noise power of 10dB is considered while in 10-15 iterations if a noise power of 20dB is considered.

Channel characteristics analysis of millimetre‐wave bands in Hyperloop scenarios based on ray‐tracing

AbstractA reliable train‐to‐ground wireless communication system is proposed for the foundation of the safe operation of Hyperloop. The wireless channel characteristics of Hyperloops at millimetre‐wave (mmWave) bands are analysed based on the ray‐tracing method. Considering the reflection paths and line of sight path, the channel transfer function expression is derived for each multipath and then the channel impulse response is obtained. On this basis, the investigation and analysis of the large‐scale and small‐scale channel characteristics, including the path loss, shadow fading, delay spread, and angular spread of 4 different mmWave frequency carriers, that is, 28/38/45/60 GHz, are conducted. Simulation results show that the path loss increases as the frequency increases while the time delay spread and angular spread almost keep unchanged. The relevant research results will contribute to the design of future Hyperloop wireless communication systems.

Virtual Reality-Based Design and Performance Simulation of Electronic and Communication Systems

Virtual Reality-Based Design and Performance Simulation of Electronic and Communication Systems

Pathloss and Airframe Shadowing Loss of Air-to-Ground UAV Channel in the Airport Area at UHF- and L-Band

In air-to-ground unmanned aerial vehicle (UAV) communications, an accurate channel propagation model is very important for the evaluation and design of communication systems. For this purpose, we have conducted several channel measurement campaigns in the airport area at UHF- and L-band (around 433 MHz and 1.518 GHz). In the line-of-sight (LoS) case, we give the distance-dependent pathloss models for both frequenciy bands. Meanwhile, it is found that the measured pathloss in the LoS scenario has a good agreement with the two-ray propagation model at short link distances. This is because of the strong ground reflection path. In the non-LoS (NLoS) case, we propose the elevation-dependent pathloss model at UHF-band based on the field measurement results. On the other hand, considering that the airframe of the UAV can block the wave propagation during the 3-D rotation in the air and the taking off and landing procedures, we specifically analyze the statistical characteristics of the airframe shadowing loss for the two cases and provide the loss distribution models for the fixed-wing, small-sized UAVs made of wood structure and carbon fiber skins.

Relay-Assisted Platooning in Wireless Networks: A Joint Communication and Control Approach

This paper addresses the problem of the joint design of the mobile communication system and the control scheme for enabling vehicle platooning applications. Vehicles communicate essential information for platooning control through multi-hop vehicle-to-vehicle (V2V) communications and are assisted in this task by Road Side Units (RSU), when available. While classical approaches, adopted in previous and current mobile systems, consider the application needs solely as requirements for the communication network, we advocate a bi-directional interaction of application and communication network. We first study the impact of different communication strategies on the application-level performance, namely the inter-vehicle distance in the platoon. Such schemes introduce a tradeoff between the packet delivery rate and the additional delay introduced by relaying. In order to assess the impact of both metrics, we start by developing a Markov model for the different communication links (inter-vehicle and vehicle-to-RSU). We then propose a cross-layer approach that adapts the application layer (platoon control parameters) to the observed Medium Access Control (MAC) layer performance. We demonstrate via simulations the benefit of the proposed relaying scheme, and that a joint design of application and communication systems is essential for enabling the integration of industrial applications in future generation networks.

Transmission model of transient flow wave signal in intelligent layered water injection system

Fluid wave code communication is used in layered water injection intelligent monitoring system, but model of fluid transient flow wave signal transmission is still unknown. Based on the fluid energy equation of steady flow, a transmission mathematical model of fluid transient flow wave signal in intelligent layered water injection system was established. The model can accurately describe the transient flow wave transmission characteristics in the tubular string of water injection wells. The transient flow wave signals and influencing factors generated by the ground electric control valve and the downhole water distributor were studied, and the transmission mechanism of the signal in the water injection tubular string was revealed. Studies show that ground and downhole transient flow wave signals are generated by discharge changes caused by changes in the opening degree of the ground valve and the downhole water distributor. The length of the water injection tube has no effect on the downlink transmission of the wellhead signal, but has a certain influence on the uploading of the downhole signal. Numerical calculations show that the flow rate of the water injection tube has a great influence on the amplitude of the pressure signal. The larger flow rate can generate larger signal amplitude, which is beneficial to the signal transmission, signal detection and processing. It was verified by the experiments and simulations that the pressure and flow changes in the downhole and wellhead had good consistency during the transmission of transient flow waves. It is found that the greater the variation of opening degree, the greater the amplitude of transient flow wave signal, which is beneficial to the wave signal transmission. The optimal settings for the valve opening are selected as 100% rightleftarrows 0%. This study has theoretical guiding significance for the design and performance improvement of fluid wave code communication systems.