Wıreless Communıcatıons Beyond 5 g: Teraherzwaves,Nano-Communıcatıons and the Internet of Bıo-Nano-Thıngs

Two promising technologies cosidered for the Beyond 5G networks are the terahertz and nano-technologies. Besides other possible application areas they hold the commitment to numerous new nano-scale solutions in the biomedical field. Nano-technology, as the name implies, examines the construction and design of nano-sized materials. These two interconnected emerging technologies have the potential to find application in quite many areas, one of the most importan being healthcare. This overview paper discusses the specifics of these technologies, their most important characteristics and introduces some of the trends for their application in the healthcare sector. In the first section terahertz frequency radio waves and their specific properties depending on the surrounding environment are discussed, followed by an introduction to nano-scale communications. Terahertz waves mandate the use of nano-scale antennas, which in turn brings us to the concept of nano-scale nodes. Nano-scale nodes are units that can perform the most basic functions of nano-machines and inter-nano-machine communications, which allow distributed nano-machines to perform more complex functions. Beyond 5G the development of these nano-communications is expected to lead to the emergence of new complex network systems. In the second part of this paper the paradigms of the Internet of Nano Things, molecular commnications and the Internet of Bio-Nano Things are discussed followed by details on their integration in healthcare related applications. The main goal of the article is to provide an introduction to these intriguing issues discussing advanced nano-technology enablers for Beyond 5G networks such as terahertz and molecular communications, nano-communications between nano-machines and the Internet of Bio-Nano-Things in light of health related applications.

     

Use of Transmission Electron Microscopy for the Characterization of Rapid Thermally Annealed, Solution-Gel, Lead Zirconate Titanate Films

The microstructure and preferred orientations of rapid thermally annealed Pb(Zr_0.53,Ti_0.47)O₃ films, deposited on Pt/Ti/SiO₂/Si electrode/substrates by solution-gel spinning, have been investigated using analytical and high-resolution electron microscopy and X-ray diffraction. The temperature of pyrolysis of the PZT films was found to influence the preferred orientation of the film: lower temperatures (350°C) favored a (111) orientation, whereas higher temperatures (420°C) favored a (100) orientation. Excess Pb was used to control the A-site stoichiometry of the film particularly at the film surface where Pb-deficient crystals could often be observed. The absence of these crystals was shown to be correlated with an improvement in the dielectric response.     

A Channel Model for Underground Sensor Networks in the Mixture of Crude Oil,Water and Soil

Future enhanced oil recovery technology can greatly benefit from the wireless sensor networks to effectively operate in underground oil reservoirs. In such a case, millimeter scale sensor nodes with antennas at the same scale have to be deployed in the confined underground oil reservoir fractures. This necessitates the sensor nodes to be operating in the THz frequency range. In this paper, the propagation based on electromagnetic （EM） waves in the Terahertz band （0.1-120.0 THz） through a crude oil/water mixture and soil medium is analyzed in order to explore its applicability in underground oil reservoir assessments. The developed model evaluates the total path loss and the absorption loss that an EM wave experiences when propagating through the crude oil/water mixture and soil medium. Our results show that sensors can communicate successfully for distances up to 1 cm. Furthermore, we have determined the existence of two transmission bands, in which the path loss is below 100 dB. Among those, the frequency window, which provides the best performance, is determined as 70 THz to 85 THz. Different path and absorption loss schemes are considered, which suggests that the 70 THz to 85 THz band is suitable for sensor communications in a medium of crude oil/water mixture and soil.     

A cross-layer fault tolerance management module for wireless sensor networks

It is a well-established fact that wireless sensor networks (WSNs) are very power constraint networks, but besides this, they are inherently more fault-prone than any other type of wireless network and their protocol design is very application specific. Major reasons for the faults are the unpredictable wireless communication channel, battery depletion, as well as fragility and mobility of the nodes. Furthermore, as traditional protocol design methods have proved inadequate, the cross-layer design (CLD) approach, which allows for interactions between different layers, providing more flexible and energy-efficient functionality, has emerged as a viable solution for WSNs. In this study we define a fault tolerance management module suitable to the requirements, limitations, and specifics of WSNs, encompassing methods for fault detection, fault prevention, fault management, and recovery. The suggested solution is in line with the CLD approach, which is an important factor in increasing the network performance. Through simulations the functionality of the network is evaluated, based on packet loss, delay, and energy consumption, and is compared with a similar solution not including fault management. The results achieved support the idea that the introduction of a unified approach to fault management improves the network performance as a whole.     

Effect of Nb Doping on the Microstructure of Sol—Gel-Derived PZT Thin Films

Aliovalent Nb doping (<10 at.%) of sol—gel-derived lead zirconate titanate (PZT) thin films was investigated with the intention of improving the ferroelectric properties. Nb addition was found to significantly alter the perovskite crystallization by stabilizing the transient pyrochlore phase, resulting in the retention of pyrochlore second phases and an increase in the perovskite lateral grain size and columnarity. The occurrence and composition of Zr-rich (surface) pyrochlore phases were found to depend on Nb concentration, annealing temperature, and Pb content. The observed changes in ferroelectric and dielectric properties as a function of Nb dopant addition were found to be strongly influenced by microstructural effects and the occurrence of pyrochlore, and hence the intrinsic effects of Nb incorporation in the perovskite lattice could not be directly ascertained.     

Application Oriented Multi Criteria Optimization in WSNs Using on AHP

With the increasing number and variety of Wireless Sensor Network (WSN) applications the need to define a suitable protocol design model that fits their specific requirements and operation has become even more pressing. The traditional methods and the well known OSI layered model prove to be inadequate for WSNs. Utilizing cross layer interactions on the other hand leads to increased efficiency in operation and prolonging the network lifetime. Similarly, proper optimization can even further add to improving the performance and reducing energy consumption in WSN. However there is no common ground to compare the suggested solutions or there is no well defined methodology for determining the optimization parameters for each specific case. In this paper we discuss two major issues: the first one is definition of optimization parameters for WSN and check for their consistency, the second one is how the suggested approach can be incorporated in a cross layer framework to provide adaptivity to different application requirements while maximizing the network performance and prolonging the network lifetime.     

Use of Ferroelectric Hysteresis Parameters for Evaluation of Niobium Effects in Lead Zirconate Titanate Thin Films

The effects of niobium doping on the hysteresis parameters of sol—gel Pb_1.1−(x/2)(Zr_0.53Ti_0.47)_1−xNb_xO₃ (0, x, 0.05) have been reported for two sets of films with analogous grain size and degree of (111) texture but with different surface microstructures. For both sets, a strong continuous decay of the remnant and maximum polarizations and slope of the hysteresis loop at the coercive field was observed with increasing niobium concentration. The field dependence of the remnant polarization for any given niobium-doped film was identical to the functional field dependence of the undoped reference film, if multiplied by a niobium-concentration-dependent constant. Although the maximum and remnant polarizations decayed as the dopant level increased, their difference remained the same value as that of the undoped film at any given field. The width of the loop (at zero polarization) was insensitive to the niobium concentration at any given field. A linear increase in coercive field asymmetry (up to 40 kV/cm) was observed with niobium addition, yet was field independent and, thus, electrostatic in origin. Niobium governed switching through a reduction of the number of switching domains, without changing the total lattice polarization response. Microstructure-related effects on switching, such as decreased volume fraction of ferroelectric material or field-screening effects due to the presence of a pyrochlore second phase, were eliminated as the origin of the hysteresis changes. This paper has demonstrated how hysteresis features and their field dependencies can be used to separate the effects of niobium-induced microstructural changes from niobium lattice doping influences on the hysteresis loops.