On the use of Diversity in Transdermal Optical Wireless Links with Nonzero Boresight Pointing Errors for Outage Performance Estimation

In this work, a diversity method is proposed for the first time in the field of transdermal optical wireless (TOW) communications, as an effective technique to enhance the outage performance of a typical TOW link. Considering both the impact of the transdermal propagation loss that experiences the optical signal through the skin along with the stochastic nature of the random misalignments between transmitter and receiver(s) terminals, an outage analysis for the total system with diversity is performed. More precisely, by jointly estimating transdermal path loss and nonzero boresight (NZB) pointing errors (PEs) effects modeled by the accurate Beckmann distribution, we derive novel closed form mathematical expressions for the outage probability (OP) of the total TOW system that employs different diversity configurations either in space, in time or in wavelength. Finally, proper numerical results are presented that demonstrate the beneficial impact of diversity on the OP performance of TOW links and verify the accuracy of our suggestions.