Channel modeling and characterization for VLC-based medical body sensor networks: trends and challenges

Optical Wireless Communication (OWC) refers to transmission in unguided propagation media through the use of optical carriers, i.e., visible, Infrared (IR), and Ultraviolet (UV) bands. In this paper, we focus on indoor Visible Light Communication (VLC)-based Medical Body Sensor Networks (MBSNs) which allow the Light Emitting Diodes (LEDs) to communicate between on-body sensors/subdermal implants and on-body central hubs/monitoring devices while also serving as a luminaire. Since the Quality-of-Service (QoS) of the communication systems depends heavily on realistic channel modeling and characterization, this paper aims at presenting an up-to-date survey of works on channel modeling activities for MBSNs. The first part reviews existing IR-based MBSNs channel models based on which VLC channel models are derived. The second part of this review provides details on existing VLC-based MBSNs channel models according to the mobility of the MBSNs on the patient’s body. We also present a realistic channel modeling approach called site-specific ray tracing that considers the skin tissue for the MBSNs channel modeling for realistic hospital scenarios.Scientific Research Projects (BAP) (Grant Number: 20A204)Publisher's Versio

Optimization of locations of diffusion spots in indoor optical wireless local area networks

In this paper, we present a novel optimization of the locations of the diffusion spots in indoor optical wireless local area networks, based on the central force optimization (CFO) scheme. The users’ performance uniformity is addressed by using the CFO algorithm, and adopting different objective function’s configurations, while considering maximization and minimization of the signal to noise ratio and the delay spread, respectively. We also investigate the effect of varying the objective function’s weights on the system and the users’ performance as part of the adaptation process. The results show that the proposed objective function configuration-based optimization procedure offers an improvement of 65% in the standard deviation of individual receivers’ performance

A New Internet of Things Hybrid VLC/RF System for m-Health in an Underground Mining Industry

This paper proposes a new system based on the Industrial Internet of Things (IIoT) for the monitoring of Mobile Health (m-Health) of workers in the underground mining industry. The proposed architecture uses a hybrid model in data transmission. Visible Light Communication (VLC) is used for downlink because of its narrow coverage, which aids in worker positioning. Radio frequency (RF) communication technology is used to send data for primary vital signs in the uplink, which is more efficient in transmission and is a viable solution according to the problem raised. The results obtained in terms of coverage and transmission for the downlink and uplink links show the feasibility of implementing the proposed system

Measurements and characterization of optical wireless communications through biological tissues

Abstract. Radio frequency (RF) has been predominantly utilized for wireless transmission of data across biological tissues. However, RF communications need to address several challenges like interference, safety, security, and privacy, which often hamper the communications through the tissues. To mitigate these challenges, light-based communication can be exploited, as optical wireless communications have unique advantages in terms of security, interference and safety. In this thesis work, we have utilized near-infrared (NIR) light to investigate the feasibility of optical wireless data transfer through biological tissues. To understand the basics of optical communications through biological tissues (OCBT), fresh meat samples and optical phantoms have been used as models of living biological tissues. An experimental testbed containing a data modulated light source and a photodetector was implemented to carry out different measurements regarding the OCBT concept. We have explored the influence of parameters like transmitted optical power, temperature of the tissue, tissue thickness, and position of the light source on the performance of the light-based through-tissue communication system. Analysis of the measurement data allowed us to compare and characterize the effect of used optical elements for better performance evaluation of the optical communication system. We have successfully transmitted a high-resolution image file through a 3 cm thick pork tissue sample. The maximum transmitted power through the tissue sample during the optical communication was 231.4 mW/cm2, which is well below the limits defined by standard of safety regulation. A data rate of 22 kilobits per second has been achieved with the experimental system. Practical limitations of the current testbed prevented obtaining a higher data throughput. The results indicate a dependence of optical received power with respect to the tissue temperature. Moreover, we found both thickness and compositional differences of the biological tissues have a significant impact on the transmittance rate. This thesis work can be considered as a part of the development of 6G technology. The outcomes of this pilot study are very promising, and in the future, numerous potential applications based on OCBT could be developed, including wireless communications to implanted devices, in-body sensors, smart pills, and others

Modern Information Systems

The development of modern information systems is a demanding task. New technologies and tools are designed, implemented and presented in the market on a daily bases. User needs change dramatically fast and the IT industry copes to reach the level of efficiency and adaptability for its systems in order to be competitive and up-to-date. Thus, the realization of modern information systems with great characteristics and functionalities implemented for specific areas of interest is a fact of our modern and demanding digital society and this is the main scope of this book. Therefore, this book aims to present a number of innovative and recently developed information systems. It is titled "Modern Information Systems" and includes 8 chapters. This book may assist researchers on studying the innovative functions of modern systems in various areas like health, telematics, knowledge management, etc. It can also assist young students in capturing the new research tendencies of the information systems' development

A Heuristic Approach for Optical Transceiver Placement to Optimize SNR and Illuminance Uniformities of an Optical Body Area Network

The bi-directional information transfer in optical body area networks (OBANs) is crucial at all the three tiers of communication, i.e., intra-, inter-, and beyond-BAN communication, which correspond to tier-I, tier-II, and tier-III, respectively. However, the provision of uninterrupted uplink (UL) and downlink (DL) connections at tier II (inter-BAN) are extremely critical, since these links serve as a bridge between tier-I (intra-BAN) and tier-III (beyond-BAN) communication. Any negligence at this level could be life-threatening; therefore, enabling quality-of-service (QoS) remains a fundamental design issue at tier-II. Consequently, to provide QoS, a key parameter is to ensure link reliability and communication quality by maintaining a nearly uniform signal-to-noise ratio (SNR) within the coverage area. Several studies have reported the effects of transceiver related parameters on OBAN link performance, nevertheless the implications of changing transmitter locations on the SNR uniformity and communication quality have not been addressed. In this work, we undertake a DL scenario and analyze how the placement of light-emitting diode (LED) lamps can improve the SNR uniformity, regardless of the receiver position. Subsequently, we show that using the principle of reciprocity (POR) and with transmitter-receiver positions switched, the analysis is also applicable to UL, provided that the optical channel remains linear. Moreover, we propose a generalized optimal placement scheme along with a heuristic design formula to achieve uniform SNR and illuminance for DL using a fixed number of transmitters and compare it with an existing technique. The study reveals that the proposed placement technique reduces the fluctuations in SNR by 54% and improves the illuminance uniformity up to 102% as compared to the traditional approach. Finally, we show that, for very low luminous intensity, the SNR values remain sufficient to maintain a minimum bit error rate (BER) of 10−9 with on-off keying non-return-to-zero (OOK-NRZ) modulation format

SAGA: Smart gateway for adaptive environments

The development of adaptive environments has the main objective of providing well-being to an individual, improving the environmental conditions of indoor environments and facilitating/automating any activity. In order to implement such systems, the use of devices capable of intercommunication and acquisition of environment-related parameters around the user is essential. Using wireless sensor networks, it is possible to monitor the various quality indices of indoor environments that can be used to develop strategies to improve quality of life of the users in personalized way. In this dissertation, a system based on a wireless sensor network that analyses and improves the environmental quality of indoor spaces, as well as evaluating the health status of an individual is presented. The system acquires and acts upon air quality and illumination quality-related parameters, as well as physiological data of a user, using sensor nodes and actuators distributed throughout the environment. Several wireless communication protocols have been implemented to enable intercommunication between the several elements present in the sensor network, such as actuators, sensor nodes and a coordinating / gateway node. Several warning mechanisms have been configured to alert the user to the presence of factors that may endanger their health, namely the presence of pollutants and thermal conditions that may trigger respiratory distress. In order to provide real-time system control including additional warning mechanisms, data analysis, a dedicated web application has been developed for this system. The user can control the environment according with his own needs and preferences through profiles configuration. The whole process of system development, hardware, software, experimental tests and contributions are included in this dissertation.A criação de ambientes adaptativos tem o principal objetivo de providenciar o bem-estar a um indivíduo, melhorar as condições do ambiente em seu redor e de facilitar/automatizar qualquer atividade. De forma a implementar tais sistemas, a utilização de dispositivos com capacidade de intercomunicação e de recolha de parâmetros relacionados com o ambiente em redor do utilizador é essencial. Com a utilização de redes de sensores sem fios, é possível monitorizar os diversos índices de qualidade de um ambiente interior e dessa forma melhorar a qualidade de vida. Nesta dissertação será apresentado um sistema baseado numa rede de sensores sem fios que permite analisar e melhorar a qualidade ambiental de espaços interiores e avaliar o estado de saúde de um indivíduo. O sistema adquire e atua sobre parâmetros relacionados com a qualidade do ar e qualidade de iluminação, assim como dados fisiológicos de um utilizador, através da utilização de nós de sensores e atuadores distribuídos pelo ambiente. Foram implementados diversos protocolos de comunicação sem fios para possibilitar a intercomunicação com outros elementos da rede, nomeadamente o nó coordenador/gateway. Foram configurados diversos mecanismos de alerta de forma a avisar o utilizador para a presença de fatores que possam colocar em risco a sua saúde, nomeadamente a presença de poluentes e condições térmicas que possam desencadear desconforto respiratório. De forma a proporcionar uma análise de dados em tempo real, controlo do sistema e dispor de mecanismos de alerta adicionais, foi desenvolvida uma aplicação Web dedicada a este sistema. Através desta, o utilizador poderá tornar o ambiente adaptável às suas características e de acordo com as suas preferências, através da configuração de perfis. Todo o processo de desenvolvimento do sistema, hardware, software, testes experimentais e contribuições serão incluídos nesta dissertação

Visible Light Optical Camera Communication for Electroencephalography Applications

Due to the cable-free deployment and flexibility of wireless communications, the data transmission in the applications of home and healthcare has shown a trend of moving wired communications to wireless communications. One typical example is electroencephalography (EEG). Evolution in the radio frequency (RF) technology has made it is possible to transmit the EEG data without data cable bundles. However, presently, the RF-based wireless technology used in EEG suffers from electromagnetic interference and might also have adverse effects on the health of patient and other medical equipment used in hospitals or homes. This puts some limits in RF-based EEG solutions, which is particularly true in RF restricted zones like Intensive Care Units (ICUs). As a recently developed optical wireless communication (OWC) technology, visible light communication (VLC) using light-emitting diodes (LEDs) for both simultaneous illumination and data communication has shown its advantages of free from electromagnetic interference, potential huge unlicensed bandwidth and enhanced data privacy due to the line transmission of light. The most recent development of VLC is the optical camera communication (OCC), which is an extension of VLC IEEE standard 802.15.7, also referred to as visible light optical camera communication (VL-OCC). Different from the conventional VLC where traditional photodiodes are used to detect and receive the data, VL-OCC uses the imaging camera as the photodetector to receive the data in the form of visible light signals. The data rate requirement of EEG is dependent on the application; hence this thesis investigates a low cost, organic LED (OLED)-driven VL-OCC wireless data transmission system for EEG applications