Nanoscale Communication Research Articles

High-speed terahertz communication with graphene-based time-modulated low-bit phase coding metasurfaces: A novel architecture for enhanced performance

Coding metasurfaces have revolutionized electromagnetic device development by enabling precise electromagnetic wave manipulation. While spatial phase modulation alone offers significant capabilities, its limitations to comprehensive control and optimal functionality are evident. As a result of recent advancements, joint amplitude-phase coding approaches have been explored using different techniques in order to enhance performance. However, such methods often result in complex structures due to the combining of various modulation techniques within meta-atoms. Addressing this challenge, this paper proposes a novel architecture for terahertz (THz) communication utilizing low-bit coding metasurfaces featuring simplified meta-atoms. Our approach introduces a coding unit cell based on graphene, combined with time-modulated coding, to enable phase and amplitude control for different harmonics. As a proof-of-concept application, we demonstrate the effectiveness of our technique in multimode vortex communication. Moreover, we show secure hologram communication by using our proposed design within the THz frequency regime. By enhancing wavefront shaping flexibility through a straightforward approach, this work lays the foundation for next-generation devices, particularly in high-speed macroscale and nanoscale communication networks.

6G THz Propagation Channel Characteristics and Modeling: Recent Developments and Future Challenges

The terahertz (THz) band is expected to play a more important role in the sixth generation (6G) communication networks. It can provide large bandwidth and high-speed transmission rate to support prospective 6G scenarios from space to ground and from macro-scale to nano-scale. However, the THz channel characteristics vary greatly for different scenarios. This paper presents a multi-dimensional overview of propagation channel characteristics and modeling for potential THz communication scenarios, including ground, space, and nano-scale communications. The atmospheric attenuation and propagation mechanisms are firstly discussed for ground scenarios. Then, the channel measurements, characteristics, and models for specific ground scenarios, including indoor office, data center, kiosk, smart rail, and massive MIMO are investigated. Following this, the THz space communication channels are summarized according to the satellite altitude. Futhermore, THz nano-scale communication channels including on-chip and body centric are analyzed. Finally, future research challenges are outlined.

Advancing Nanoscale Communication: Unveiling the Potential of Terahertz and Molecular Communication

In recent years, advancements in nanotechnology have opened up new frontiers in communication systems, bringing the dream of seamless communication at the nanoscale level closer to reality [...]

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.

Nanonetworking in the Terahertz Band and Beyond

The possibility to control matter at the atomic and molecular scale opens the door to new types of devices that exhibit unprecedented physical properties. For the wireless communications community, the development of miniature transceivers and antennas that operate in traditionally uncharted frequency bands of the electromagnetic spectrum opens the door to transformative applications across scales (from nano to macro), domains (biological and non-biological), and realms (from classical to quantum). In this article, the state of the art in electromagnetic nanoscale communication and networks is presented by following a bottom-up approach. After describing some innovative applications of this technology, the fundamental physical properties and capabilities of nano-transceivers and nano-antennas at optical and terahertz frequencies are reviewed. The main phenomena affecting the propagation of the generated signals are then presented both from the wave and particle perspectives. Starting from the hardware capabilities and the channel peculiarities, tailored communication and networking solutions are discussed, all defining a roadmap to transform fundamental research into socially-meaningful applications.

Diversity-Based Non-Coherent Signal Detector for Molecular Communication via Reaction-Diffusion

Molecular communication is attractive to the emerging nano-scale communication systems. Traditionally, a detector recovers the information from only the concentration of single messenger molecule, while ignoring the variation of multiple participants in biochemical reaction. In this paper, we propose a non-coherent signal detector, by fully exploiting this ubiquitous biochemical diversity property of multiple reacting molecules. After extracting the channel state information (CSI) independent non-coherent features of received signals, the dynamical transient characteristics of messenger, reactant and product molecules are all utilized to implement the diversity detection, thus formulating a functional single-input multiple-output (SIMO) system via reaction-diffusion communication that has been barely considered before. We design both hard and soft combination strategies to attain the potential diversity gain arise from the dynamical co-variation of participants. Theoretical analysis and numerical simulations are provided to demonstrate the advantages of our detector. Compared with conventional detectors that use only single messenger molecule, the bit error rate (BER) of is substantially reduced. Moreover, the BER performances of our non-coherent detector are even better than coherent maximum a posteriori (MAP) detector that requires accurate CSI estimation, which confirms the dramatic diversity gain provided by our detector. It would have great potentials in reliable nano-scale communications.

Levenberg–Marquardt Method-Based Cooperative Source Localization in SIMO Molecular Communication via Diffusion Systems

Molecular communication underpins nano-scale communications in nanotechnology. The combination of multi-nanomachines to form nano-networks is one of the main enabling methods. Due to the importance of source localization in establishing nano-networks, this paper proposes a cooperative source localization method for Molecular Communication via Diffusion (MCvD) systems using multiple spherical absorption receivers. Since there is no exact mathematical expression of the channel impulse response for multiple absorbing receivers, we adopt an empirical expression and use Levenberg-Marquardt method to estimate the distance of the transmitter to each receiver, based on which the location of the transmitter is obtained using an iterative scheme where the initial point is obtained using a multi-point localization method. Particle based simulation is carried out to evaluate the performance of the proposed method. Simulation results show that the proposed method can accurately estimate the location of transmitter in short to medium communication ranges.

Joint Communication and Bio-Sensing With Plasmonic Nano-Systems to Prevent the Spread of Infectious Diseases in the Internet of Nano-Bio Things

With the advances in nanotechnology, novel nanosensing technologies can play a pivotal role in today’s society. Plasmonic sensing has demonstrated unprecedented detection reliability and resolution in a very compact form factor. Traditional plasmonic sensors leverage biofunctionalized metallic grating structures whose frequency response in transmission or reflection changes according to the presence of targeted biomarkers. However, these sensing setups require bulky measurement equipment to couple light to and from sensors for excitation and detection. In parallel, for over a decade, the nanoscale electromagnetic communication community has been leveraging plasmonic structures to transmit information at the nanoscale efficiently. By combining the two realms, this paper proposes the concept of joint nanoscale communication and bio-sensing systems enabled by plasmonic sensing nanoantennas. Sensing nanonodes can communicate from nanonode to nanonode for intra-body networks and from nanonode to a wearable device which, by leveraging the edge, can process and transmit the sensing information to the cloud, resulting in accurate diagnosis and reduced load on the medical testing infrastructure. First, we model the changes in the frequency response of a biofunctionalized plasmonic nanoantenna when exposed to different biomarkers. Then, we propose a chirp-spread spectrum excitation and detection system to enable simultaneous communication and sensing at the nanoscale. We present a data-driven human tissue model for communication through human tissue. We also present numerical results to demonstrate the performance of the proposed system.

Architectures of nano-networks of communications in the internet of nano-things IONT

Nanotechnology provides solutions to different problems, such as biomedical, industrial, agricultural and military fields. So, nano-networks are used for nano-scale communication between different nano-devices in the different Nano-Network architectures. But when a nano-network is connected to the Internet, it becomes a new paradigm called the Internet of Nano-Things.
 
 Therefore, the objective of this article is to analyze the most important concepts of nano-networks, applications and projects. IoNT architectures based on the proposals of Akyildiz and Jornet, the complementary security architecture by Sicari, Rizzardi, Piro, Coen-Porosini and Grieco and the nano- network architecture proposed by Akram Galal and Xavier Hesselbach will be reviewed. Finally, technological trends at the IoNT level and the challenges in terms of security, privacy, communication and energy will be reviewed.

Molecular index modulation using convolutional neural networks

As the potential of molecular communication via diffusion (MCvD) systems at nano-scale communication increases, designing molecular schemes robust to the inevitable effects of molecular interference has become of vital importance. There are numerous molecular approaches in literature aiming to mitigate the effects of interference, namely inter-symbol interference. Moreover, for molecular multiple-input–multiple-output systems, interference among antennas, namely inter-link interference, becomes of significance. Inspired by the state-of-the-art performances of machine learning algorithms on making decisions, we propose a novel approach of a convolutional neural network (CNN)-based architecture. The proposed approach is for a uniquely-designed molecular multiple-input–single-output topology in order to alleviate the damaging effects of molecular interference. In this study, we compare the performance of the proposed network with that of an index modulation approach and a symbol-by-symbol maximum likelihood estimation and show that the proposed method yields better performance.

Design of Plasmonic Yagi-Uda Nanoantennas for Chip-Scale Optical Wireless Communications.

Optical wireless transmission has recently become a major cutting-edge alternative for on-chip/inter-chip communications with higher transmission speeds and improved power efficiency. Plasmonic nanoantennas, the building blocks of this new nanoscale communication paradigm, require precise design to have directional radiation and improved communication ranges. Particular interest has been paid to plasmonic Yagi–Uda, i.e., the optical analog of the conventional Radio Frequency (RF) Yagi–Uda design, which may allow directional radiation of plasmonic fields. However, in contrast to the RF model, an overall design strategy for the directional and optimized front-to-back ratio of the radiated far-field patterns is lacking. In this work, a guide for the optimized design of Yagi–Uda plasmonic nanoantennas is shown. In particular, five different design conditions are used to study the effects of sizes and spacing between the constituent parts (made of Au). Importantly, it is numerically demonstrated (using the scattered fields) that closely spaced nanoantenna elements are not appropriated for directional light-to-plasmon conversion/radiation. In contrast, if the elements of the nanoantenna are widely spaced, the structure behaves like a one-dimensional array of nanodipoles, producing a funnel-like radiation pattern (not suitable for on-chip wireless optical transmission). Therefore, based on the results here, it can be concluded that the constituent metallic rib lengths must be optimized to exhibit the resonance at the working wavelength, whilst their separations should follow the relation , where indicates the effective wavelength scaling for plasmonic nanostructures.

New Insights on Molecular Communication in Nano Communication Networks and their Applications

The advancement in nanotechnology has carved out a way to establish a powerful base to fall on for implementation of nanoscale machines having the capability to carry out significant yet trivial tasks. This impetus has led the researchers to continually bring up various solutions for implementing and executing nanoscale communications taking into consideration of biological as well as electromagnetic communication. The primary aims are expanding the abilities of nanoscale devices to integrated multiple composite tasks by reciprocated coordination, which can be carried out through this communication type. This paper describes the current research developments in nano communication networks, focusing on molecular communication (MC). MC makes use of molecules as an information transporter between nanoscale machines. Molecules help in enciphering messages to send between a sender and a receiver. MC has, thereby, become an inseparable part of the IoNT (Internet of Nano-Things) as a communication model among nanoscale machines. This paper also gives a description of the design of MC systems and various channelling models used to address the various challenges and opportunities in this new upcoming and developing field. In addition, this review article is also inclusive of an investigative survey on the recent developments in this field.

Sucrose-Responsive Intercommunicated Janus Nanoparticles Network.

Inspired by biological systems, the development of artificial nanoscale materials that communicate over a short distance is still at its early stages. This work shows a new example of a cooperating system with intercommunicated devices at the nanoscale. The system is based on the new sucrose-responsive Janus gold-mesoporous silica (Janus Au-MS) nanoparticles network with two enzyme-powered nanodevices. These nanodevices involve two enzymatic processes based on invertase and glucose oxidase, which are anchored on the Au surfaces of different Janus Au-MS nanoparticles, and N-acetyl-L-cysteine and [Ru(bpy)3]2+ loaded as chemical messengers, respectively. Sucrose acts as the INPUT, triggering the sequential delivery of two different cargoes through the enzymatic control. Nanoscale communication using abiotic nanodevices is a developing potential research field and may prompt several applications in different disciplines, such as nanomedicine.

Synthetic Cells Engaged in Molecular Communication: An Opportunity for Modelling Shannon- and Semantic-Information in the Chemical Domain

In this Perspective article we intend to focus on the opportunity of modelling Shannon information and/or “semantic” information in the field originated by the convergence of bottom-up synthetic biology (in particular, the construction of “synthetic cells”) and the engineering approaches to molecular communication. In particular we will argue that the emerging technology of synthetic cell fabrication will allow novel opportunities to study nano-scale communication and manipulation of information in unprecedented manner. More specifically, we will discuss the possibility of enquiring on the transfer and manipulation of information in the chemical domain, and interpreting such a dynamics according to Shannon or to MacKay-Bateson (“semantic” information).

Information theoretic modeling of paranodal regions in myelinated axons

As a natural form of nanoscale communication, neuro-spike communication inspires the deployment of nanomachines inside the human body for healthcare. To this end, the identification of failure mechanisms in normal and diseased connections of nervous nano-networks is crucial. Thus, in this paper, we investigate the information transmission through a single myelinated axon segment. We introduce a realistic multi-compartmental model for a single myelinated segment by incorporating the axon's paranodal regions to the model. Next, we characterize the myelinated segment communication channel in terms of attenuation over the range of frequencies. Based on this, we derive the rate per channel use and upper bound on the information capacity. The performance evaluations reveal that our approach provides dramatic correction regarding frequency response. We believe that this result could have a significant effect on the characterization of demyelinated axons from the information and communication technology (ICT) perspective.

Inhibition of Tunneling Nanotubes between Cancer Cell and the Endothelium Alters the Metastatic Phenotype

The interaction of tumor cells with blood vessels is one of the key steps during cancer metastasis. Metastatic cancer cells exhibit phenotypic state changes during this interaction: (1) they form tunneling nanotubes (TNTs) with endothelial cells, which act as a conduit for intercellular communication; and (2) metastatic cancer cells change in order to acquire an elongated phenotype, instead of the classical cellular aggregates or mammosphere-like structures, which it forms in three-dimensional cultures. Here, we demonstrate mechanistically that a siRNA-based knockdown of the exocyst complex protein Sec3 inhibits TNT formation. Furthermore, a set of pharmacological inhibitors for Rho GTPase–exocyst complex-mediated cytoskeletal remodeling is introduced, which inhibits TNT formation, and induces the reversal of the more invasive phenotype of cancer cell (spindle-like) into a less invasive phenotype (cellular aggregates or mammosphere). Our results offer mechanistic insights into this nanoscale communication and shift of phenotypic state during cancer–endothelial interactions.

Securing the Insecure: A First-Line-of-Defense for Body-Centric Nanoscale Communication Systems Operating in THz Band.

This manuscript presents a novel mechanism (at the physical layer) for authentication and transmitter identification in a body-centric nanoscale communication system operating in the terahertz (THz) band. The unique characteristics of the propagation medium in the THz band renders the existing techniques (say for impersonation detection in cellular networks) not applicable. In this work, we considered a body-centric network with multiple on-body nano-senor nodes (of which some nano-sensors have been compromised) who communicate their sensed data to a nearby gateway node. We proposed to protect the transmissions on the link between the legitimate nano-sensor nodes and the gateway by exploiting the path loss of the THz propagation medium as the fingerprint/feature of the sender node to carry out authentication at the gateway. Specifically, we proposed a two-step hypothesis testing mechanism at the gateway to counter the impersonation (false data injection) attacks by malicious nano-sensors. To this end, we computed the path loss of the THz link under consideration using the high-resolution transmission molecular absorption (HITRAN) database. Furthermore, to refine the outcome of the two-step hypothesis testing device, we modeled the impersonation attack detection problem as a hidden Markov model (HMM), which was then solved by the classical Viterbi algorithm. As a bye-product of the authentication problem, we performed transmitter identification (when the two-step hypothesis testing device decides no impersonation) using (i) the maximum likelihood (ML) method and (ii) the Gaussian mixture model (GMM), whose parameters are learned via the expectation–maximization algorithm. Our simulation results showed that the two error probabilities (missed detection and false alarm) were decreasing functions of the signal-to-noise ratio (SNR). Specifically, at an SNR of 10 dB with a pre-specified false alarm rate of , the probability of correct detection was almost one. We further noticed that the HMM method outperformed the two-step hypothesis testing method at low SNRs (e.g., a increase in accuracy was recorded at SNR = −5 dB), as expected. Finally, it was observed that the GMM method was useful when the ground truths (the true path loss values for all the legitimate THz links) were noisy.

Temperature-aware routing protocol for Intrabody Nanonetworks

Intrabody Nanonetworks (IBN) are composed of nanosensors that have tremendous potential to enable cellular level monitoring and precision in drug delivery and diagnosis. Nanoscale communication using Electromagnetic (EM) waves propagation in the Terahertz (THz) band suffers from molecular absorption noise that has been regarded as the leading cause of heat generation along with antenna communication radiations. In the presented work, we propose a novel Temperature–Aware routing protocol (TA-IBN) that explicitly addresses the thermal related constraints of IBN. The proposed routing scheme aims at stabilizing the temperature in the whole network by avoiding congestion and preventing temperature rise in the heated regions. To avoid temperature rise, nanorouters estimate the temperature increase in their region and excludes data collection from the hotspots areas. Moreover, during data collection, nanonodes’ selection is also optimized based on data freshness to enable reporting of a more accurate state of physiological parameters with minimized antenna radiation exposure time. The temperature increase analysis provided in this work can also be used for safety health assessment in medical applications. We have evaluated the performance of TA-IBN by conducting extensive simulations using the Nano-SIM tool. In addition, we compare TA-IBN with the flooding scheme and Thermal-Aware Routing Algorithm (TARA) to gain further insights into our proposed protocol TA-IBN. The results obtained confirm that our protocol ensures safer intrabody routing and traffic distribution in different regions to normalize temperature rise, avoid congestion, and reduce the communication delay.

Protected Long-Distance Guiding of Hypersound Underneath a Nanocorrugated Surface.

In nanoscale communications, high-frequency surface acoustic waves are becoming effective data carriers and encoders. On-chip communications require acoustic wave propagation along nanocorrugated surfaces which strongly scatter traditional Rayleigh waves. Here, we propose the delivery of information using subsurface acoustic waves with hypersound frequencies of ∼20 GHz, which is a nanoscale analogue of subsurface sound waves in the ocean. A bunch of subsurface hypersound modes are generated by pulsed optical excitation in a multilayer semiconductor structure with a metallic nanograting on top. The guided hypersound modes propagate coherently beneath the nanograting, retaining the surface imprinted information, at a distance of more than 50 μm which essentially exceeds the propagation length of Rayleigh waves. The concept is suitable for interfacing single photon emitters, such as buried quantum dots, carrying coherent spin excitations in magnonic devices and encoding the signals for optical communications at the nanoscale.

Performance Analysis of Transmission Rate and Decoding Rate Using Minimum Energy Channel Codes for Nanoscale Wireless Communication

An energy efficient communication system is required for the improvement of nanoscale wireless communication. In this paper, we defined minimum energy coding scheme (MEC) to achieve energy efficiency in wireless nanosensor network. MEC maintains the desire code distance to provide reliability and better decoding probability, while requiring less energy to transmit bits of information. We proposed a relationship between transmission rate and decoding rate which is significant for minimum energy channel codes in nanoscale wireless communication. We investigated the performance evaluation of code length limited and energy limited transmission rates on the source cardinality which ensures that for any value of code distance, code length limited transmission rate will be decreased in regard to increasing the value of source cardinality and vice versa for energy limited transmission rate. We studied the optimum value of transmission rate and decoding rate which confirms that if the number of carriers is increased n times, then the optimum transmission and decoding rate would also be increased n times. We also studied the performance evaluation of code distance which is inversely propotional to transmission distance and correct decoding probability. Further, we examined the dependance of average energy per bit which is proportional to symbol duration and bandwidth. On the contrary, spectral efficiency is inversely proportional to symbol duration. We strongly believe that our proposed relationship between transmission rate and decoding rate accompanied by the performance evaluation of various parameters will improve the nanoscale wireless communication system.