G. K. Varotsos, H. E. Nistazakis, K. Aidinis, G. D. Roumelas, F. Jaber and K. K. M. Rahman, "Modulated Retro-Reflector Transdermal Optical Wireless Communication Systems with Wavelength Diversity over Skin-Induced Attenuation and Pointing Errors," 2019 IEEE International Symposium on Signal Processing and Information Technology (ISSPIT), Ajman, United Arab Emirates, pp. 1-5, 2019