Chirp Spread Spectrum Modulation for Intrabody Nanoscale Communication and Sensing

Optical signals are commonly used for intrabody applications, such as nano-bio-sensing and imaging and, more recently, nanoscale communication. However, due to the interaction of light with the building blocks of different body tissues, including different types of cells, organelles, and molecular components, the intrabody channel is highly frequency selective, compromising the communication between intrabody nano-devices as well as wearable devices. In this paper, Chirp Spread Spectrum (CSS) modulation is proposed as a way to overcome the frequency selectivity of the optical channel in intrabody applications. More specifically, after reviewing and highlighting the key properties of the intrabody optical channel, the performance of CSS analytically derived. Extensive numerical results are provided both for a generic optical frequency selective channel and for the near-infrared optical in-vivo channel to illustrate the performance of CSS. The obtained results demonstrate how the possibility to detach the symbol duration from the actual signal bandwidth leads to low bit error rates even when operating in very low signal to noise ratio conditions.