Ke Yang

Numerical Analysis and Characterization of THz Propagation Channel for Body-Centric Nano-Communications

This paper presents the characteristics of electromagnetic waves propagating inside human body at Terahertz frequencies and an initial study of the system performance of nano-network. It has been observed that the path loss is not only the function of distance and frequency but also related to the dielectric loss of human tissues. Numerical results have been compared with analytical studies and a good match has been found which validates the proposed numerical model. Based on the calculation of path losses and noise level for THz wave propagation, the channel capacity is studied to give an insight of future nano-communications within the human body. Results show that at the distance of millimeters, the capacity can reach as high as 100 Terabits per second (Tbps) depending on the environment and exciting pulse types.

Terahertz Communications in Human Tissues at the Nanoscale for Healthcare Applications

This letter investigates nanoscale wireless communications in human tissues. Starting from propagation models, validated through real experiments, channel capacity and transmission ranges are derived for different physical transmission settings. Results highlight the challenges characterizing the communication in such a medium, thus, paving the way to novel research activities devoted to the design of pioneering nanomedical applications.

In-vivo characterisation and numerical analysis of the THz radio channel for nanoscale body-centric wireless networks

Analytical investigations are presented to calculate the path loss and absorption coefficients of human tissues such as blood and fat at THz frequencies as an essential part of understanding nanoscale networks. From the results, it can be seen that with the rise of the distance and frequency, the path loss increases slightly as expected. For the blood, the path loss at 1mm is around 100dB while for the fat the corresponding distance to the path loss of 100dB is approximately 2mm, leading to the conclusion that at very short distances, in the order of millimeters, the path loss is not significantly high to consider communication between nano-devices.

Terahertz Channel Characterization Inside the Human Skin for Nano-Scale Body-Centric Networks

This paper focuses on the development of a novel radio channel model inside the human skin at the terahertz range, which will enable the interaction among potential nano-machines operating in the inter cellular areas of the human skin. Thorough studies are performed on the attenuation of electromagnetic waves inside the human skin, while taking into account the frequency of operation, distance between the nano-machines and number of sweat ducts. A novel channel model is presented for communication of nano-machines inside the human skin and its validation is performed by varying the aforementioned parameters with a reasonable accuracy. The statistics of error prediction between simulated and modeled data are: mean (μ)= 0.6 dB and standard deviation (σ)= 0.4 dB, which indicates the high accuracy of the prediction model as compared with measurement data from simulation. In addition, the results of proposed channel model are compared with terhaertz time-domain spectroscopy based measurement of skin sample and the statistics of error prediction in this case are: μ = 2.10 dB and σ = 6.23 dB, which also validates the accuracy of proposed model. Results in this paper highlight the issues and related challenges while characterizing the communication in such a medium, thus paving the way towards novel research activities devoted to the design and the optimization of advanced applications in the healthcare domain.

Nano-Communication for Biomedical Applications: A Review on the State-of-the-Art From Physical Layers to Novel Networking Concepts

Nano-communication-based devices have the potential to play a vital role in future healthcare technologies by improving the quality of human life. Its application in medical diagnostics and treatment has a great potential, because of its ability to access small and delicate body sites noninvasively, where conventional medical devices fall short. In this paper, the state of the art in this field is presented to provide a comprehensive understanding of current models, considering various communication paradigms, antenna design issues, radio channel models based on numerical and experimental analysis and network, and system models for such networks. Finally, open research areas are identified for the future directions within the field.

Numerical analysis of the communication channel path loss at the THz band inside the fat tissue

With the growth of the demand of smaller and smaller implantable devices, THz technologies becomes appealing for potential applications in Body Area Networks at nano-scale. As an essential part for understanding the in-body propagation at THz frequency numerical investigations are presented in this paper to simulate the absorption path loss of fat at THz frequency. The results of the proposed analysis suggest that a distance in the order of millimeter might be suitable to guarantee a communication link between nano-devices located in human tissues.

THz Time-Domain Spectroscopy of Human Skin Tissue for In-Body Nanonetworks

This paper presents experimental study of real human skin material parameter extraction based on terahertz (THz) time-domain spectroscopy in the band 0.1-2.5 THz. Results in this paper show that electromagnetic properties of the human skin distinctively affect the path loss and noise temperature parameters of the communication link, which are vital for channel modeling of in-body nanonetworks. Refractive index and absorption coefficient values are evaluated for dermis layer of the human skin. Repeatability and consistency of the data are accounted for in the experimental investigation and the morphology of the skin tissue is verified using a standard optical microscope. Finally, the results of this paper are compared with the available work in the literature, which shows the effects of dehydration on the path loss and noise temperature. The measured parameters, i.e., the refractive index and absorption coefficient are 2.1 and 18.45 cm-1, respectively, at 1 THz for a real human skin, which are vital for developing and optimizing future in-body nanonetworks.

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.

Understanding and characterizing nanonetworks for healthcare monitoring applications

Terahertz (THz) region of the electromagnetic spectrum has been of wide interest during the past few years. It has been regarded as the promising working band for Nanoscale Communication. In this paper, experimental investigations and analysis using THz-TDS (THz Time Domain Spectroscopy) system are presented and discussed. The study is focused on biological modeling of artificial skin and thereby extracting the refractive index values at the THz band. The paper also compares the results with already reported papers. The results are promising and in agreement with minor variation due to different growth process and experimental environment.

Cooperative In-Vivo Nano-Network Communication at Terahertz Frequencies

Nano-devices have great potential to play a vital role in future medical diagnostics and treatment technologies because of its non-invasive nature and ability to reach delicate body sites easily as compared with conventional devices. In this paper, a novel concept of cooperative communication for in vivo nano-network is presented to enhance the communication among these devices. The effect on the system outage probability performance is conducted for various parameters, including relay placement, number of relays, transmit power, bandwidth, and carrier frequency. Results show approximately a tenfold increase in the system outage performance whenever an additional relay is included in the cooperative network, and hence show a great potential of using cooperative communication to enhance the performance of nano-network at terahertz frequencies.