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

Design and implementation of an uplink connection for a light-based IoT node

Abstract. In the wake of soaring demand for shrinking radio frequency (RF) spectrum, light-fidelity (LiFi) has been heralded as a solution to accommodate resources for future communication networks. Infrared (IR) and visible light communication (VLC) are meant to be used within LiFi because of numerous advantages. By combining the paradigm of internet of things (IoT) along with LiFi, light-based IoT (LIoT) emerges as a potential enabler of future 6G networks. With tremendous number of interconnected devices, LIoT nodes need to be able to receive and transmit data while being energy autonomous. One of the most promising clean energy sources comes from both natural and artificial light. In addition to providing illumination and energy, light can also be utilized as a robust information carrier. In order to provide bidirectional connectivity to LIoT node, both downlink and uplink have to be taken into consideration. Whereas downlink relies on visible light as a carrier, uplink approach can be engineered freely within specific requirements. With this in mind, this master’s thesis explores possible solutions for providing uplink connectivity. After analysis of possible solutions, the LIoT proof-of-concept was designed, implemented and validated. By incorporating printed solar cell, dedicated energy harvesting unit, power-optimised microcontroller unit (MCU) and light intensity sensor the LIoT node is able to autonomously transmit data using IR

Challenges and Opportunities of Optical Wireless Communication Technologies

In this chapter, we present various opportunities of using optical wireless communication (OWC) technologies in each sector of optical communication networks. Moreover, challenges of optical wireless network implementations are investigated. We characterized the optical wireless communication channel through the channel measurements and present different models for the OWC link performance evaluations. In addition, we present some technologies for the OWC performance enhancement in order to address the last-mile transmission bottleneck of the system efficiently. The technologies can be of great help in alleviating the stringent requirement by the cloud radio access network (C-RAN) backhaul/fronthaul as well as in the evolution toward an efficient backhaul/fronthaul for the 5G network. Furthermore, we present a proof-of-concept experiment in order to demonstrate and evaluate high capacity/flexible coherent PON and OWC links for different network configurations in the terrestrial links. To achieve this, we employ advanced modulation format and digital signal processing (DSP) techniques in the offline and real-time mode of the operation. The proposed configuration has the capability to support different applications, services, and multiple operators over a shared optical fiber infrastructure

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

A Low, Cost Portable Ground Station to Track and Communicate with Satellites in VHF Band

In this thesis, we present the architecture and implementation of a low-cost, small, mobile and easily deployable ground station to track and receive signals from satellites that operate on the VHF-band (144 MHz to 147 MHz). The ground station uses a handheld 5-dB gain Yagi-Uda antenna, a low noise amplifier with 23 dB gain and a software defined radio (FUNcube Dongle) to receive the signals. The analog front end’s software-defined nature gives it the flexibility to target satellites with diverse power, modulation and error-correcting schemes. Software for satellite tracking, signal decoding and processing is freely-available. The low cost of the ground station makes its affordable for classroom and laboratory activities in a research or educational institution that involve satellite signal processing in wireless communication courses. The small size and portability of the proposed ground station means it can be adopted in locations with limited access to fixed outdoor antennas, whether because of financial, regulatory or other restrictions. Examples of ground station-tracked and received signals include satellites such as FUNcube (AO-73), International Space Station (ISS) and NOAA satellites. Specifically, the National Oceanographic and Atmospheric Administration (NOAA) series of satellites (NOAA 15, 18, 19) were tracked. The signals received were processed to recover images of the earth using various software. This thesis also presents the details of decoding the image using MATLAB

LI_FI Overview and Implementation in Medical Field

With the wide use of wireless gadgets, the demand of wireless internet is increasing at a very high pace and stealing it from the guy next door, or competing for bandwidth at a conference, the slow speeds you face when more than one device is tapped into the network. When many devices access wireless internet, clogged airwaves are going to make it. To over come this there is a solution known as "Data through illumination". This technology is known as "LI - FI" Li - Fi is a technology that makes use of LED light which helps in the transmission of data much faster and flexible than data tha t can be transmitted through Wi - Fi. Light reaches nearly everywhere so communication can also go along with light freely. Light Fidelity is a branch of optical wireless communication which is an emerging technology. By using visible light as transmission medium, Li - Fi provides wireless indoor communication. The bit rate achieved by Li - Fi cannot be achieved by Wi - Fi. Li - Fi is the transfer of data through light by taking fiber out of fiber optics and sending data through LED light. In this paper we are concerned with the use of li - fi in the field of medicine. As the wi - fi cannot be used along with the medical equipments due to the radio waves we implement li - fi in those places

Single- and dual-carrier microwave noise abatement in the deep space network

The NASA/JPL Deep Space Network (DSN) microwave ground antenna systems are presented which simultaneously uplink very high power S-band signals while receiving very low level S- and X-band downlinks. Tertiary mechanisms associated with elements give rise to self-interference in the forms of broadband noise burst and coherent intermodulation products. A long-term program to reduce or eliminate both forms of interference is described in detail. Two DSN antennas were subjected to extensive interference testing and practical cleanup program; the initial performance, modification details, and final performance achieved at several planned stages are discussed. Test equipment and field procedures found useful in locating interference sources are discussed. Practices deemed necessary for interference-free operations in the DSN are described. Much of the specific information given is expected to be easily generalized for application in a variety of similar installations. Recommendations for future investigations and individual element design are given

Long Term Evolution-Advanced and Future Machine-to-Machine Communication

Long Term Evolution (LTE) has adopted Orthogonal Frequency Division Multiple Access (OFDMA) and Single Carrier Frequency Division Multiple Access (SC-FDMA) as the downlink and uplink transmission schemes respectively. Quality of Service (QoS) provisioning is one of the primary objectives of wireless network operators. In LTE-Advanced (LTE-A), several additional new features such as Carrier Aggregation (CA) and Relay Nodes (RNs) have been introduced by the 3rd Generation Partnership Project (3GPP). These features have been designed to deal with the ever increasing demands for higher data rates and spectral efficiency. The RN is a low power and low cost device designed for extending the coverage and enhancing spectral efficiency, especially at the cell edge. Wireless networks are facing a new challenge emerging on the horizon, the expected surge of the Machine-to-Machine (M2M) traffic in cellular and mobile networks. The costs and sizes of the M2M devices with integrated sensors, network interfaces and enhanced power capabilities have decreased significantly in recent years. Therefore, it is anticipated that M2M devices might outnumber conventional mobile devices in the near future. 3GPP standards like LTE-A have primarily been developed for broadband data services with mobility support. However, M2M applications are mostly based on narrowband traffic. These standards may not achieve overall spectrum and cost efficiency if they are utilized for serving the M2M applications. The main goal of this thesis is to take the advantage of the low cost, low power and small size of RNs for integrating M2M traffic into LTE-A networks. A new RN design is presented for aggregating and multiplexing M2M traffic at the RN before transmission over the air interface (Un interface) to the base station called eNodeB. The data packets of the M2M devices are sent to the RN over the Uu interface. Packets from different devices are aggregated at the Packet Data Convergence Protocol (PDCP) layer of the Donor eNodeB (DeNB) into a single large IP packet instead of several small IP packets. Therefore, the amount of overhead data can be significantly reduced. The proposed concept has been developed in the LTE-A network simulator to illustrate the benefits and advantages of the M2M traffic aggregation and multiplexing at the RN. The potential gains of RNs such as coverage enhancement, multiplexing gain, end-to-end delay performance etc. are illustrated with help of simulation results. The results indicate that the proposed concept improves the performance of the LTE-A network with M2M traffic. The adverse impact of M2M traffic on regular LTE-A traffic such as voice and file transfer is minimized. Furthermore, the cell edge throughput and QoS performance are enhanced. Moreover, the results are validated with the help of an analytical model