Patient Mobility Support for Indoor Non-Directed Optical Body Area Networks

Abstract

In this paper, a patient mobility support scheme for indoor non-directed optical body area networks (OBAN) is presented. The OBAN is an optical healthcare system where medical sensors are installed on various parts of the patient’s body and are connected to an optical coordinator for transmitting the physiological signals via optical wireless links. In the proposed scheme, a white light-emitting diode (LED) was employed as the optical coordinator that was mounted on the patient body, while a photodetector (PD) was used as the receiver installed at the ceiling. We considered three practical mobility scenarios in terms of the location of the coordinator: (i) Shoulder, (ii) wrist, and (iii) both shoulder and wrist. The analytical channel model for multiple reflections in a non-directed OBAN was developed and validated in the form of simulations. In addition, experiments were carried out to verify the effectiveness of the proposed mobility scheme. It was found that the third scenario (shoulder and wrist) performed best, showing a bit error rate (BER) of 1.2 × 10−6 at a distance of 1.25 m. The experimental results demonstrated that the proposed mobility support scheme in the OBAN added an additional degree of freedom to patients with reliable performances.

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

“…Besides, even though the receiver height may vary with the posture under consideration, it is assumed to be at the desktop level of 0.85 m, unless stated otherwise. To perform the ray-tracing simulations, a room that has often been used in the literature with the dimensions of 5 × 5 × 3 m 3 has been considered [9,11]. Given the typical low data-rates that are used in OBANs, the room furniture has a negligible impact on the main characteristics of the channel [28,29]; hence, it is not considered in the study.…”

“…While all of these studies focused on a single-user environment, Refs. [ 9 , 24 , 25 ] discussed the use of VLC in multi-user environments. Recently, the authors in [ 26 ] characterized the intra-OBAN channels by considering the effects of mobility and shadowing that occurred as a result of body parts and realistic body movements.…”

“…Accordingly, it is imperative that the data collected by the coordinator from the SNs at tier- II must be transmitted/ received reliably to/from the AP and vice versa to avoid any mishaps. While reliability in OBANs depends on several factors, such as blocking effects [ 6 ], ambient light interference [ 8 ], and mobility [ 9 ], broadly, it primarily relies on the received levels at the photodetector (PD) which in turn determine the system performance. For a typical OBAN employing IM/DD with OOK-NRZ modulation format, the required theoretical is 15.6 dB to maintain a minimum (threshold) BER of [ 6 , 10 ].…”

Channel Characterization and Modeling for Optical Wireless Body-Area Networks

“…On the other hand, channel characterization for extra-WBAN links (i.e., between a CN and an AP located in the room) was considered in [31]- [34], where user mobility was considered based on uniformly distributed random user positions and orientations of the sources/detectors. The patient's body was modeled by a simple rectangular surface in [31], [33], and by a combination of three rectangular volumes in [34], whereas a static three-dimensional (3D) model was used in [32]. Recently, in [35], we considered extra-WBAN channel characterization and modeling using a similar MCRT approach as in the present work.…”

Channel characterization for optical extra-WBAN links considering local and global user mobility

“…Also, the effect of patient's body was neglected in. 5 In, 6,7 user mobility was taken into account based on random user positions and random orientations of the sources and the detectors, considering uniform distributions. In contrast to these works, which consider simplified models, our study is based on more accurate and more realistic models with an acceptable level of details, in particular, concerning the body 3D shape and user mobility.…”