Modelling of the Terahertz Communication Channel for In-vivo Nano-networks in the Presence of Noise

This paper focuses on the modelling of communication channel noise inside human tissues at the THz band (0.1-10THz). A novel model is put forward based on the study of the physical mechanism of the channel noise in the medium, which takes into account both the radiation of the medium and the molecular absorption from the transmitted signal. The derivation and the general concepts of the noise modelling is detailed in the paper. The results show that the channel noise power spectral density at the scale of several micrometres is at acceptable levels and the value tends to decrease with the increase of both distance and frequency. In addition, the channel noise is also related to the composition of the human tissues, with the result of higher channel noise in tissues with higher water concentration. The conclusion drawn from the conducted study and analysis paves the way for more comprehensive characterisation of the electromagnetic channel within in-vivo nano-networks

Analytical modelling of the effect of noise on the terahertz in-vivo communication channel for body-centric nano-networks

The paper presents an analytical model of the terahertz (THz) communication channel (0.1 - 10 THz) for in-vivo nano-networks by considering the effect of noise on link quality and information rate. The molecular absorption noise model for in-vivo nano-networks is developed based on the physical mechanisms of the noise present in the medium, which takes into account both the radiation of the medium and the molecular absorption from the transmitted signal. The signal-to-noise ratio (SNR) of the communication channel is investigated for different power allocation schemes and the maximum achievable information rate is studied to explore the potential of THz communication inside the human body. The obtained results show that the information rate is inversely proportional to the transmission distance. Based on the studies on channel performance, it can be concluded that the achievable transmission distance of in-vivo THz nano-networks should be restrained to approximately 2 mm maximum, while the operation band of in-vivo THz nano-networks should be limited to the lower band of the THz band. This motivates the utilisation of hierarchical/cooperative networking concepts and hybrid communication techniques using molecular and electromagnetic methods for future body-centric nano-networks

Feasibility study of the THz band for communications between wearable electronics

Emerging wearable nano sensor networks enable a set of valuable applications in biomedical and environmental fields. At the same time, the current state of communication technologies significantly limits the processing capabilities of prospective nanomachines. Consequently, implying that all the analysis of collected data needs to be performed on a macro device. Therefore, to effectively enable long-awaited applications of nano networks their seamless integration into existing networking infrastructure is required, leading to the concept of Internet of Nano Things. In this paper, the interoperability between already deployed macro networks and emerging nano networks is preliminary investigated. The solution for this problem is nontrivial, as the existing macro wireless networks use primarily the carrier-based electromagnetic communications, while nanomachines must rely on ultra-low-power pulse-based EM radiation or inherently mobile objects as information carriers. Thus, the direct interaction between macro and nano networks is currently not feasible, forcing using special gateway nodes. Moreover, the modern solutions for nano communications have to be rapidly improved to enable construction of large-scale networks on top of existing link level techniques. Numerous theoretical questions are to be addressed to achieve this goal, ranging from the design of a proper modulation and coding technique to mitigation of noise and interference effects

Power Distribution and Performance Analysis of Terahertz Communication in Artificial Skin

Apart from the effect of path loss and signal-dependent molecular absorption noise, the capabilities of in-vivo nano-communication at the Terahertz (THz) frequencies are also strictly influenced by the distribution of power transmission in the frequency domain. In this paper, the artificial skin with different fibroblast cell densities are considered as THz communication medium; signal-to-noise ratio (SNR) and channel capacity as a function of the transmitted signal power in flat and Gaussian-shaped distribution is quantified. In addition, the achievable communication distance of THz wave inside the artificial skin is evaluated. The results show that, SNR increases sharply with the rise of the transmitted signal power from -90 dBW to -30 dBW in flat distribution, and from -90 dBW to -40 dBW in Gaussian distribution; after the critical value, there is minor improvement when further increasing the power. The achievable communication range of THz wave inside the artificial skin is strictly limited to about 1 to 2 mm, and the specific distance depends on the medium composition. Gaussian-shaped power distribution can provide higher SNR but lower capacity compared with flat distribution. The obtained results provide fundamentals in building future intra-body nanonetworks

Single and multi-user capacity of communication by silence in terahertz band

Nanotechnology utilizes the operation of nano-sensors also called nano-machines. Nano-machines are very small in size, about a few hundreds of nanometers. At the nanoscale, single nano-machine has very limited functionalities so it is able to perform only a simple task. However, the group of nano-machine can perform complex tasks when they communicate among themselves. The tasks performed by those machines have applications in the field of biomedical, environmental, and military. There are various models of communication among nano machines, like electromagnetic wireless communication, molecular communication, acoustic communication, nano-mechanical communication model. In this studies, electromagnetic wireless communication model is used with the latest advancement in graphene based electronic. Graphene and its derivatives points that the frequency range of operation of future electronic nano-machines is terahertz band (0.1 – 10.0 THz). This band of frequency is still unlicensed and it can theoretically support a very large transmission speed. Nano-machines, due to its small size have resource constrain. Nano-machines with nano-batteries are typically characterized by a limited energy supply. Hence, to overcome the power limitation, there is a need of an energy-efficient communication paradigm. Such an energy-efficient communication paradigm is communication through silence (CtS) strategy. This strategy enables energy-efficient information transfer within the nano-machines. In CtS, information is transmitted using silence period which makes this strategy energy-efficient. This thesis is focused in this new communication paradigm, CtS. The performance from this strategy is evaluated in terms of channel capacity for both single and multiple user cases in terahertz band. A propagation model for terahertz band based on radiative transfer theory is used to calculate the total path loss and the molecular absorption noise that a travelling wave suffers. Chanel capacity was formulated in this studies using those parameters. Analytical result in this studies shows that the performance is very high for both lower distance like, 1 meter and lower number of water vapour (H2O) molecules

Performance comparison of selected wired and wireless networks on chip architectures

In this paper we compare performance intra-core communications in network on chips.We consider two alternative architectures, wired and wireless. The wired on is based on a common bus (ring) with all the cores attached to it. We compare it to the mesh (point-to-point) architecture based on THz wireless links operating in 0.1-0.54 frequency band. Using reference latencies of inter-core communications in modern CPUs we perform an applicability assessment of considered schemes. As performance metrics of interest we consider both delay and capacity. Our results indicate that the latter architecture outperforms the former by a singificant margin. The proposed system can be realized implementing directional antennas at all cores and ensuring that cores are placed on a chip such that there is no interference between them

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

Analytical characterisation of the terahertz in-vivo nano-network in the presence of interference based on TS-OOK communication scheme

The envisioned dense nano-network inside the human body at terahertz (THz) frequency suffers a communication performance degradation among nano-devices. The reason for this performance limitation is not only the path loss and molecular absorption noise, but also the presence of multi-user interference and the interference caused by utilising any communication scheme, such as time spread ON—OFF keying (TS-OOK). In this paper, an interference model utilising TS-OOK as a communication scheme of the THz communication channel inside the human body has been developed and the probability distribution of signal-to-interference-plus-noise ratio (SINR) for THz communication within different human tissues, such as blood, skin, and fat, has been analyzed and presented. In addition, this paper evaluates the performance degradation by investigating the mean values of SINR under different node densities in the area and the probabilities of transmitting pulses. It results in the conclusion that the interference restrains the achievable communication distance to approximate 1 mm, and more specific range depends on the particular transmission circumstance. Results presented in this paper also show that by controlling the pulse transmission probability and node density, the system performance can be ameliorated. In particular, SINR of in vivo THz communication between the deterministic targeted transmitter and the receiver with random interfering nodes in the medium improves about 10 dB, when the node density decreases one order. The SINR increases approximate 5 and 2 dB, when the pulse transmitting probability drops from 0.5 to 0.1 and 0.9 to 0.5