On the Outage Capacity of Transdermal Optical Wireless Links with Stochastic Spatial Jitter and Skin-Induced Attenuation

George K Varotsos,Konstantinos Aidinis,Hector E Nistazakis

doi:10.3390/photonics8120553

George K Varotsos, Konstantinos Aidinis + Show 1 more

Open Access

https://doi.org/10.3390/photonics8120553

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Abstract

The tremendous development of both optical wireless communications (OWC) and implantable medical devices (IMDs) has recently enabled the establishment of transdermal optical wireless (TOW) links that utilize light waves to transfer information inside the living body to the outside world and conversely. Indeed, numerous emerging medical applications such as cortical recording and telemetry with cochlear implants require extremely high data rates along with low power consumption that only this new technology could accommodate. Thus, in this paper, a typical TOW link is investigated in terms of outage capacity which is a critical performance metric that has so far not been evaluated for such wireless systems in the open technical literature. More precisely, an outage capacity analysis is performed considering both skin-induced attenuation and stochastic spatial jitter, i.e., pointing error effects. Analytical expressions and results for the outage capacity are derived for a variety of skin channel conditions along with varying stochastic pointing errors which demonstrate the feasibility of this cross-field cooperation. Lastly, the corresponding simulation outcomes further validate our suggestions.

Highlights

An outage capacity analysis was performed, while novel analytical expressions were derived for this crucial performance metric which incorporate the most significant parameters and effects that play a key role in transdermal optical wireless (TOW) performance and availability
Their analytical results which were validated by proper simulations reveal that the achievable TOW outage capacity largely depends on the average electrical signal-to-noise ratio (SNR) at the receiver’s side, as well as on stochastic pointing errors’ strength, along with transdermal propagating distance for the information-bearing light which penetrates into the skin channel
The feasibility of establishing high-speed TOW links was demonstrated for typical transdermal link lengths, even in very harsh pointing mismatch conditions

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Many emerging medical applications such as recording neural signals from in-body devices and actuating these devices from out-of-body signals to guide a prosthesis, require even higher capacities to emulate similar performance to that of human organs, such as the cochlea, along with lower power consumption [5,6,7,8,9,10] Another representative example ofthe need forhigher-speed bidirectional transdermal communication than RF is when neural signals are recorded, sampled, processed, and used to actuate artificial limbs for rehabilitation human affected by paralysis resulting from stroke, head injury, spinal cord injury, and other neurological disorders. Analytical outage capacity expressions are derived with their corresponding results verifying the accuracy of our proposed analysis over a wide average electrical SNR range

System and Channel Model

Outage Capacity

Analytical Results

Discussion and Conclusions