A comprehensive survey on hybrid communication in context of molecular communication and terahertz communication for body-centric nanonetworks

With the huge advancement of nanotechnology over the past years, the devices are shrinking into micro-scale, even nano-scale. Additionally, the Internet of nano-things (IoNTs) are generally regarded as the ultimate formation of the current sensor networks and the development of nanonetworks would be of great help to its fulfilment, which would be ubiquitous with numerous applications in all domains of life. However, the communication between the devices in such nanonetworks is still an open problem. Body-centric nanonetworks are believed to play an essential role in the practical application of IoNTs. BCNNs are also considered as domain specific like wireless sensor networks and always deployed on purpose to support a particular application. In these networks, electromagnetic and molecular communications are widely considered as two main promising paradigms and both follow their own development process. In this survey, the recent developments of these two paradigms are first illustrated in the aspects of applications, network structures, modulation techniques, coding techniques and security to then investigate the potential of hybrid communication paradigms. Meanwhile, the enabling technologies have been presented to apprehend the state-of-art with the discussion on the possibility of the hybrid technologies. Additionally, the inter-connectivity of electromagnetic and molecular body-centric nanonetworks is discussed. Afterwards, the related security issues of the proposed networks are discussed. Finally, the challenges and open research directions are presented

Fundamentals of electromagnetic nanonetworks in the terahertz band

Nanotechnology is providing a new set of tools to the engineering community to design nanoscale components with unprecedented functionalities. The integration of several nano-components into a single entity will enable the development of advanced nanomachines. Nanonetworks, i.e., networks of nanomachines, will enable a plethora of applications in the biomedical, environmental, industrial and military fields. To date, it is still not clear how nanomachines will communicate. The miniaturization of a classical antenna to meet the size requirements of nanomachines would impose the use of very high radiation frequencies. The available transmission bandwidth increases with the antenna resonant frequency, but so does the propagation loss. Due to the expectedly very limited power of nanomachines, the feasibility of nanonetworks would be compromised if this approach were followed. Therefore, a new wireless technology is needed to enable this paradigm. The objective of this thesis is to establish the foundations of graphene-enabled electromagnetic communication in nanonetworks. First, novel graphene-based plasmonic nano-antennas are proposed, modeled and analyzed. The obtained results point to the Terahertz Band (0.1-10 THz) as the frequency range of operation of novel nano-antennas. For this, the second contribution in this thesis is the development of a novel channel model for Terahertz Band communication. In addition, the channel capacity of the Terahertz Band is numerically investigated to highlight the potential of this still-unregulated frequency band. Third, a novel modulation based on the transmission of femtosecond-long pulses is proposed and its performance is analyzed.% in terms of achievable information rates. Fourth, the use of low-weight codes to prevent channel errors in nanonetworks is proposed and investigated. Fifth, a novel symbol detection scheme at the receiver is developed to support the proposed modulation scheme. Sixth, a new energy model for self-powered nanomachines with piezoelectric nano-generators is developed. Moreover, a new Medium Access Control protocol tailored to the Terahertz Band is developed. Finally, a one-to-one nano-link is emulated to validate the proposed solutions.Ph.D

Antennas and Electromagnetics Research via Natural Language Processing.

Advanced techniques for performing natural language processing (NLP) are being utilised to devise a pioneering methodology for collecting and analysing data derived from scientific literature. Despite significant advancements in automated database generation and analysis within the domains of material chemistry and physics, the implementation of NLP techniques in the realms of metamaterial discovery, antenna design, and wireless communications remains at its early stages. This thesis proposes several novel approaches to advance research in material science. Firstly, an NLP method has been developed to automatically extract keywords from large-scale unstructured texts in the area of metamaterial research. This enables the uncovering of trends and relationships between keywords, facilitating the establishment of future research directions. Additionally, a trained neural network model based on the encoder-decoder Long Short-Term Memory (LSTM) architecture has been developed to predict future research directions and provide insights into the influence of metamaterials research. This model lays the groundwork for developing a research roadmap of metamaterials. Furthermore, a novel weighting system has been designed to evaluate article attributes in antenna and propagation research, enabling more accurate assessments of impact of each scientific publication. This approach goes beyond conventional numeric metrics to produce more meaningful predictions. Secondly, a framework has been proposed to leverage text summarisation, one of the primary NLP tasks, to enhance the quality of scientific reviews. It has been applied to review recent development of antennas and propagation for body-centric wireless communications, and the validation has been made available for comparison with well-referenced datasets for text summarisation. Lastly, the effectiveness of automated database building in the domain of tunable materials and their properties has been presented. The collected database will use as an input for training a surrogate machine learning model in an iterative active learning cycle. This model will be utilised to facilitate high-throughput material processing, with the ultimate goal of discovering novel materials exhibiting high tunability. The approaches proposed in this thesis will help to accelerate the discovery of new materials and enhance their applications in antennas, which has the potential to transform electromagnetic material research

A White Paper on Broadband Connectivity in 6G

Executive Summary This white paper explores the road to implementing broadband connectivity in future 6G wireless systems. Different categories of use cases are considered, from extreme capacity with peak data rates up to 1 Tbps, to raising the typical data rates by orders-of-magnitude, to support broadband connectivity at railway speeds up to 1000 km/h. To achieve these goals, not only the terrestrial networks will be evolved but they will also be integrated with satellite networks, all facilitating autonomous systems and various interconnected structures. We believe that several categories of enablers at the infrastructure, spectrum, and protocol/algorithmic levels are required to realize the intended broadband connectivity goals in 6G. At the infrastructure level, we consider ultra-massive MIMO technology (possibly implemented using holographic radio), intelligent reflecting surfaces, user-centric and scalable cell-free networking, integrated access and backhaul, and integrated space and terrestrial networks. At the spectrum level, the network must seamlessly utilize sub-6 GHz bands for coverage and spatial multiplexing of many devices, while higher bands will be used for pushing the peak rates of point-to-point links. The latter path will lead to THz communications complemented by visible light communications in specific scenarios. At the protocol/algorithmic level, the enablers include improved coding, modulation, and waveforms to achieve lower latencies, higher reliability, and reduced complexity. Different options will be needed to optimally support different use cases. The resource efficiency can be further improved by using various combinations of full-duplex radios, interference management based on rate-splitting, machine-learning-based optimization, coded caching, and broadcasting. Finally, the three levels of enablers must be utilized not only to deliver better broadband services in urban areas, but also to provide full-coverage broadband connectivity must be one of the key outcomes of 6G

Single- versus Multi-Carrier Terahertz-Band Communications: A Comparative Study

The prospects of utilizing single-carrier (SC) and multi-carrier (MC) waveforms in future terahertz (THz)-band communication systems remain unresolved. On the one hand, the limited multi-path components at high frequencies result in frequency-flat channels that favor low-complexity wideband SC systems. On the other hand, frequency-dependent molecular absorption and transceiver characteristics and the existence of multi-path components in indoor sub-THz systems can still result in frequency-selective channels, favoring off-the-shelf MC schemes such as orthogonal frequency-division multiplexing (OFDM). Variations of SC/MC designs result in different THz spectrum utilization, but spectral efficiency is not the primary concern with substantial available bandwidths; baseband complexity, power efficiency, and hardware impairment constraints are predominant. This paper presents a comprehensive study of SC/MC modulations for THz communications, utilizing an accurate wideband THz channel model and highlighting the various performance and complexity trade-offs of the candidate schemes. Simulations demonstrate that discrete-Fourier-transform spread orthogonal time-frequency space (DFT-s-OTFS) achieves a lower peak-to-average power ratio (PAPR) than OFDM and OTFS and enhances immunity to THz impairments and Doppler spreads, but at an increased complexity cost. Moreover, DFT-s-OFDM is a promising candidate that increases robustness to THz impairments and phase noise (PHN) at a low PAPR and overall complexity.Comment: 18 pages, 12 figures, journa

Enabling Technology in Optical Fiber Communications: From Device, System to Networking

This book explores the enabling technology in optical fiber communications. It focuses on the state-of-the-art advances from fundamental theories, devices, and subsystems to networking applications as well as future perspectives of optical fiber communications. The topics cover include integrated photonics, fiber optics, fiber and free-space optical communications, and optical networking

Efficient Communication Protocols for Wireless Nanoscale Sensor Networks

Advances in nanotechnology are paving the way for wireless nanoscale sensor networks (WNSNs), promising radically new applications in medical, biological, and chemical fields. However, the small scale poses formidable challenges for communication. First, small nanomaterial-based antennas communicate in the terahertz band, which coincides with the natural resonance frequencies of many types of molecules causing severe molecular absorption and noise. The problem is particularly complicated if the molecular composition of the channel changes over time, causing time-varying absorption and noise. Second, as it is not practical to fit large batteries or replace batteries in a small device, these devices are expected to power themselves by harvesting ambient energy from the environment. However, the amount of energy that can be harvested is directly proportional to the size of the harvester. A nanodevice therefore can generate only a tiny fraction of its total power consumption, which requires us to rethink the design of communication protocols for self-powering WNSNs. In order to address aforementioned challenges, this thesis makes three fundamental contributions. First, it proposes dynamic frequency and power selection as a means to overcome the first problem, i.e, changing molecular composition problem in a time-varying terahertz channel. The dynamic frequency/power selection problem is modelled as a Markov Decision Process to derive the optimal solutions, while several practical heuristics are proposed that achieve close to optimal solutions. Second, to address the severe power shortage problem in a self-powering nanodevice, this thesis proposes a mechanism to exploit the information contained in the energy harvesting data to detect the energy-dissipating events occurring in the environment. This form of event monitoring makes dual use of the energy-harvesting unit in the nanodevice, i.e., it is used to generate power as well as monitor the environment, thus saving significant energy, which otherwise would have been used to power the onboard sensors. Finally, novel WNSN applications are designed and analysed to monitor and control chemical reactors at the molecular level with the ultimate goal of increasing the selectivity of the reactor. It is shown that using the proposed communication protocols for a time-varying terahertz channel, the selectivity of the reactor can be significantly increased, beyond what can be achieved with conventional solutions

Horn Antennas and Dual-Polarized Circuits in Substrate Integrated Waveguide (SIW) Technology

The Substrate Integrated Waveguide (SIW) technology is a very promising candidate to provide widespread commercial solutions for modern communications systems. Its main advantage is the possibility to integrate passive/active components and antennas in the same substrate by using standard manufacturing processes, such as the Printed Circuits Board (PCB) processing technique. Nevertheless, the production of low-cost SIW devices is inherently linked to commercially available substrates and fabrication methods. In particular, these constraints usually limit (a) the frequency range of operation of certain SIW antennas and (b) the possibility of creating multimode structures dealing with orthogonal polarizations. The motivation of this PhD thesis is to overcome these two limitations by proposing innovative SIW components based on PCBs in order to favour the compatibility with existing systems and to lower their cost. Hence, the usage of the SIW technology would be extended towards new applications and scenarios. One type of antenna strongly affected by the limitation (a) is the H-plane SIW horn antenna. While standard horns are employed in many applications and in a wide range of frequencies, their counterparts in SIW technology are restricted to the Ka-band and above. At lower frequencies, commercial substrates are electrically thin and the performances of these end-fire antennas severely diminish. To solve this problem, a novel low-profile SIW horn antenna has been designed to be used at the Ku-band and below, while offering wideband characteristics. In addition, the horn shape has been further optimized to reduce the antenna footprint for a given directivity. In order to overcome the limitation (b), a substrate integrated guide able to simultaneously carry orthogonally polarized modes has been developed: the so called Extended Substrate Integrated Waveguide (ESIW). An ESIW dual-polarized system composed of an Orthomode Transducer (OMT) feeding a dual-polarized horn antenna has been designed and experimentally verified. The overall combination of concepts and ideas proposed in this thesis opens the door towards new SIW components that can increase the capacity, robustness and compactness ofmodern communication systems