Wave-based Communication Research Articles

Long-term Decline of the Spotted Salamander (Ambystoma maculatum) in an Undeveloped Landscape

Abstract The Eastern Hellbender (Cryptobranchus alleganiensis alleganiensis) is a giant, charismatic species of salamander of conservation concern. Despite growing interest in their breeding behavior, significant gaps remain in our understanding of hellbender reproduction, particularly the behavior occurring immediately prior to and during breeding, as these activities typically occur within the nesting cavity and out of view. In this study, we used custom-built infrared cameras installed underwater in artificial nesting shelters to record pre-breeding behaviors, complete mating sequences, and failed mating attempts in eleven shelters. Using these recordings, we describe the basic mating sequence, the presence of potential alternative mating tactics, and two novel behaviors, including possible signal production via wave-based communication and unique egg laying behavior by female hellbenders. These findings add to our understanding of hellbenders’ life history as well as informing conservation efforts in both captive and wild environments.

Self-Organized Aggregation Behavior Based on Virtual Expectation of Individuals with Wave-Based Communication

In this study, a microscopic model for a swarm of mobile robots is developed to implement self-organized aggregation behavior. The proposed model relies on the concept of subjective expectation, which is defined as the “minimum wished cluster size” of a robot in the swarm. During the whole process, a robot’s expectation constantly changes based on context awareness. This awareness is obtained by employing a low-cost communication system commonly found in swarm robot studies: infrared-based communication. Robots can make their own decisions by comparing their expected and estimated observed cluster sizes, which leads to macroscopic swarm aggregation. However, due to the limitations of local communication and mobility, robots are restricted in their ability to perceive global information, particularly regarding cluster size. Inspired by the slime mold aggregation process, a wave-based communication mechanism is implemented to help robots estimate a cluster size. Moreover, each transmission includes a modulated message that allows robots to explicitly share their knowledge with others. In this way, despite the fact that the robot may not belong to that cluster due to its perception range, it can easily grasp the cluster size when passing the cluster. Once a robot detects a desired cluster, it can approach this cluster with its direction determined by using average origin of wave (AOW) method. The performance of the aggregation algorithm was tested both in simulation and with a real swarm robot. Dispersion metrics and cluster metrics were employed to evaluate the proposed algorithm’s performance. The results show that the proposed microscopic model utilizes collective behavior which aggregates all randomly distributed robots into a single aggregate cluster with a reasonable swarm density and evaluation time.

A reflective metasurface for broadband OAM vortex wave generation

In this paper, we proposed a reflective metasurface which controls the phase delay of the electromagnetic (EM) wave through geometric phase manipulation. By coding the metasurface unit cells in different orientation angles, an orbital angular momentum (OAM) wave can be obtained through the metasurface reflection. A broadband reflective OAM wave with mode l = −1 was demonstrated which was experimentally observed from 8.3 GHz to 11.6 GHz. The mode spectrum of OAM wave was analyzed and the spectrum weight was about 0.82 through numerical calculation and about 0.47 through experimental measurement for the mode l = −1. The realization of this broadband OAM wave has the potential application to improve the OAM wave based communication capacity.

Impact of surface reactance and skin depth for effective surface wave-based communication between the integrated circuits of printed circuit board

Impact of surface reactance and skin depth for effective surface wave-based communication between the integrated circuits of printed circuit board

Impact of surface reactance and skin depth for effective surface wave-based communication between the integrated circuits of printed circuit board

The copper traces for printed circuit board (PCB) applications proved to be less suitable for high frequency communications. Surface wave communication-based wave guide with the properties of high field confinement at its conductor and the dielectric interface along with less dispersion, suits well for inter chip communication at higher frequencies. For effective wave propagation through the proposed channel, an analysis on the surface reactance and skin depth is required, which also accounts for proper channel construction. This research focuses mainly on these parameters to come up with the optimal channel design conditions. From the complete analysis, the high surface reactance of the channel with lower skin depth levels gives path to high channel propagation efficiency, keeping the height of the dielectric to a particular level, and the optimal surface power integration throughout the channel is achieved. The analysis was performed considering different frequency levels ranging from 100 GHz to 500 GHz. Considering surface reactance over the j100 to j400 range, which results in power integration up to 99.6% at the interface of conductor and dielectric, it is better than the theoretical values of copper traces.

Sub-μWRComm: 415-nW 1–10-kb/s Physically and Mathematically Secure Electro-Quasi-Static HBC Node for Authentication and Medical Applications

Low-power secure communication is one of the key enablers of applications, such as secure authentication and remote health monitoring. Radio wave-based communication method, such as Bluetooth, suffers from high-power requirements and physical signal leakage. Electro-quasi-static human body communication (EQS-HBC) utilizes the conductivity of the human body to use it as a communication medium and confine the signal within a close proximity of the body and enable low power consumption through low-frequency operation. This makes EQS-HBC an attractive alternative for such low-power, low-data-rate secure communication. In this article, we present the first >1 kb/s Sub- ${\underline {\mu}} \text{W}$ W ea R able Comm unication (Sub- $\mu $ WRComm), a secure EQS-HBC node, which uses EQS-HBC for physical security and an AES-256 engine for mathematical security and operate at sub- $\mu \text{W}$ power budget. The signal confinement property of EQS-HBC is demonstrated through finite element method (FEM) simulations and leakage measurements, establishing its security property. The Sub- $\mu $ WRComm system consumes only 415-nW total power, with 108-nW active power at the lowest power mode, operating at a data rate of 1 kb/s with −64-dBm sensitivity making it suitable for authentication and remote monitoring applications. This work presents a $100\times $ improvement compared with state-of-the-art HBC implementations while providing simultaneous physical and mathematical security for the first time.

On the Safety of Human Body Communication.

Human Body Communication (HBC) utilizes the electrical conductivity properties of the human body to communicate between devices in and around the body. The increased energy-efficiency and security provided by HBC compared to traditional radio wave based communication makes it a promising alternative to communicate between energy constrained wearable and implantable devices around the body.However, HBC requires electrical signals to be transmitted through the body, which makes it essential to have a thorough analysis of the safety aspects of such transmission. This paper looks into the compliance of the current density and electric/magnetic fields generated in different modalities of HBC with the established safety standards. Circuit and Finite Element Method (FEM) based simulations are carried out to quantitatively find the compliance of current density and fields with the established safety limits. The results show the currents and fields in capacitive HBC are orders of magnitude smaller than the specified limits. However, certain excitation modalties in galvanic HBC can result in current densities and fields exceeding the safety limits around the excitation point on the body near the electrode. A study with 7 human subjects (4 male, 3 female) is carried out over a month, using capacitive HBC.The study monitors the change in 5 vital parameters (Heart Rate, Mean Arterial Pressure, Respiration Rate, Peripheral Capillary Oxygen Saturation, Temperature), while wearing a HBC enabled device. Analysis of the acquired data statistically shows no significant change in any of the vital parameters of the subjects, confirming the results of the simulation study.

On Integrated Access and Backhaul Networks: Current Status and Potentials

In this article, we introduce and study the potentials and challenges of integrated access and backhaul (IAB) as one of the promising techniques for evolving 5G networks. We study IAB networks from different perspectives. We summarize the recent Rel-16 as well as the upcoming Rel-17 3GPP discussions on IAB, and highlight the main IAB-specific agreements on different protocol layers. Also, concentrating on millimeter wave-based communications, we evaluate the performance of IAB networks in both dense and suburban areas. Using a finite stochastic geometry model, with random distributions of IAB nodes as well as user equipments (UEs) in a finite region, we study the service coverage rate defined as the probability of the event that the UEs’ minimum rate requirements are satisfied. We present comparisons between IAB and hybrid IAB/fiber-backhauled networks where a part or all of the small base stations are fiber-connected. Finally, we study the robustness of IAB networks to weather and various deployment conditions and verify their effects, such as blockage, tree foliage, rain as well as antenna height/gain on the coverage rate of IAB setups, as the key differences between the fiber-connected and IAB networks. As we show, IAB is an attractive approach to enable the network densification required by 5G and beyond.

Gravitational wave emission from quadrupole Josephson junction device

We suggest a hybrid quantum mechanical/classical set up capable of gravitational wave emission. The proposed device consists of two superconducting tunneling junctions which act as quantum voltage-to-frequency converters and produce oscillation of the charges (masses) in the superconducting condensate. The classical interpretation of the set up is associated with the particular arrangement which leads to suppression of the dipole radiation and formation of time dependent quadrupole mass moment - the gravitational wave source. The proposed device converts electrical energy/momentum into gravitational ones thus suggesting a form of propulsion. Provided the reverse effect: curvature-to-voltage conversion is possible, the device represents an emitter-receiver pair for gravitational wave based communication (favorable 1/r fall off with distance).

Chirped self-similar solitary waves for the generalized nonlinear Schrödinger equation with distributed two-power-law nonlinearities.

We investigate the propagation characteristics of the chirped self-similar solitary waves in non-Kerr nonlinear media within the framework of the generalized nonlinear Schrödinger equation with distributed dispersion, two-power-law nonlinearities, and gain or loss. This model contains many special types of nonlinear equations that appear in various branches of contemporary physics. We extend the self-similar analysis presented for searching chirped self-similar structures of the cubic model to a more general problem involving two nonlinear terms of arbitrary power. A variety of exact linearly chirped localized solutions with interesting properties are derived in the presence of all physical effects. The solutions comprise bright, kink and antikink, and algebraic solitary wave solutions, illustrating the potentially rich set of self-similar pulses of the model. It is shown that these optical pulses possess a linear chirp that leads to efficient compression or amplification, and thus are particularly useful in the design of optical fiber amplifiers, optical pulse compressors, and solitary wave based communication links. Finally, the stability of the self-similar solutions is discussed numerically under finite initial perturbations.

Design of a New Stress Wave-Based Pulse Position Modulation (PPM) Communication System with Piezoceramic Transducers.

Stress wave-based communication has great potential for succeeding in subsea environments where many conventional methods would otherwise face excessive difficulty, and it can benefit logging well by using the drill string as a conduit for stress wave propagation. To achieve stress wave communication, a new stress wave-based pulse position modulation (PPM) communication system is designed and implemented to transmit data through pipeline structures with the help of piezoceramic transducers. This system consists of both hardware and software components. The hardware is composed of a piezoceramic transducer that can generate powerful stress waves travelling along a pipeline, upon touching, and a PPM signal generator that drives the piezoceramic transducer. Once the transducer is in contact with a pipeline surface, the generator integrated with an amplifier is utilized to excite the piezoceramic transducer with a voltage signal that is modulated to encode the information. The resulting vibrations of the transducer generates stress waves that propagate throughout the pipeline. Meanwhile, piezoceramic sensors mounted on the pipeline convert the stress waves to electric signals and the signal can be demodulated. In order to enable the encoding and decoding of information in the stress wave, a PPM-based communication protocol was integrated into the software system. A verification experiment demonstrates the functionality of the developed system for stress wave communication using piezoceramic transducers and the result shows that the data transmission speed of this new communication system can reach 67 bits per second (bps).

In situ realization of particlelike scattering states in a microwave cavity

We realize scattering states in a lossy and chaotic two-dimensional microwave cavity which follow bundles of classical particle trajectories. To generate such particlelike scattering states we measure the system's transmission matrix and apply an adapted Wigner-Smith time-delay formalism to it. The necessary shaping of the incident wave is achieved in situ using phase and amplitude regulated microwave antennas. Our experimental findings pave the way for establishing spatially confined communication channels that avoid possible intruders or obstacles in wave-based communication systems.

Optimal Clustering in Underwater Wireless Sensor Networks: Acoustic, EM and FSO Communication Compliant Technique

With a wide scope for exploration and research, underwater wireless sensor network (UWSN) is a fast growing research area in current scenario. UWSNs need energy efficient designing approach, because underwater sensor nodes are battery driven. Also the deployed batteries cannot be easily recharged by non-conventional energy resources, like solar energies. Clustering is an effective technique to design an energy efficient UWSNs. Due to the sparse deployment of nodes and dynamic nature of the channel, the clustering characteristics of UWSNs are different from those of terrestrial wireless sensor networks. In this paper, we focused on optimal clustering for UWSNs which are compliant with any one of the acoustic, free space optical (FSO) and electromagnetic (EM) wave-based communication techniques. Besides, we proposed an energy dissipation model of sensor node for FSO and EM wave-based communication and compared with the contemporary energy dissipation model for acoustic-based communication. In particular, the suitability of the above three techniques for underwater communication is investigated and their performance is compared on the basis of energy consumption and optimal clustering.

EM-Based High Speed Wireless Sensor Networks for Underwater Surveillance and Target Tracking

Underwater Wireless Sensor Networks (UWSNs) are considered as tangible, low cost solution for underwater surveillance and exploration. Existing acoustic wave-based UWSN systems fail to meet the growing demand for fast data rates required in military operations, oil/gas exploration, and oceanographic data collection. Electromagnetic (EM) wave-based communication systems, on the other hand, have great potential for providing high speed data rates in such scenarios. This paper will(1)discuss the challenges faced in the utilization of EM waves for the design of tactical underwater surveillance systems and(2)evaluate several EM wave-based three-dimensional (3D) UWSN architectures differing in topologies and/or operation principles on the performance of localization and target tracking. To the best of our knowledge, this is the first of its kind in the field of underwater communications where underwater surveillance techniques for EM wave-based high speed UWSNs have been investigated. Thus, this will be a major step towards achieving future high speed UWSNs.

Frequency, Temperature and Salinity Variation of the Permittivity of Seawater

With the emergence of unmanned marine robots, underwater communication systems have received much attention in recent years. To successfully develop radio wave based communication solutions, it is essential to understand properties of electromagnetic wave transmission in seawater. These properties are determined by the frequency variation of the permittivity of seawater. Existing models for the permittivity of saline water are empirical ones that best fit experimental data. We propose a physically realistic model, similar to the one used in plasma physics, for the variation of the dielectric constant of water with varying frequencies and salinities. Our model is in excellent agreement with existing empirical fits for frequencies between 1 and 256 GHz. We use this model to study the propagation of electromagnetic waves in seawater. We explain that large propagation distances would be possible at MHz frequencies if the conductivity of seawater decreases at small field strengths due to the hydrogen bonding of water molecules. However, we were unable to experimentally verify any reduction in the conductivity of seawater