Molecular communication nanonetworks inside human body

To realize molecular nanonetworks, the foundations of molecular information theory should be established through identification of the existing molecular communication mechanisms, and architectures and networking techniques for nanomachines should be developed, which demand novel engineering efforts. Luckily, these engineering skills and technology have been prepared for us by the natural evolution in the last several billions of years. Indeed, the human body is a massive nanoscale molecular communications network as it is composed of billions of interacting nanomachines, i.e., cells. Intra-body biological systems are closely linked to each other and communicate primarily through molecular transactions. Thus, vital activities inside the human body are regulated by everlasting communication performance and operations of intra-body molecular nanonetworks. However, natural intra-body molecular nanonetworks are yet to be explored with the elegant tools of information and communication theories. In this paper, first, the elementary models for significant intra-body molecular communication channels, i.e., nanoscale neuro-spike communication channel, action potential-based cardiomyocyte molecular communication channel, and hormonal molecular communication channel, are introduced. Next, molecular nanonetworks belonging to multi-terminal extensions of channel models, i.e., nervous, cardiovascular molecular, and endocrine nanonetworks are discussed. Furthermore, heterogeneous communication network of intra-body molecular nanonetworks together with five senses, i.e., nanosensory networks, is explored from the perspectives of communication and network theories. Moreover, open research challenges, such as extension of molecular channel models to multi-terminal cases, and developing a communication theory perspective to understand the physiology and to capture potential communication failures of intra-body biological systems, are provided. Our objectives are to learn from the elegant molecular communication mechanisms inside us for engineering practical communication techniques for emerging nanonetworks, as well as to pave the way for the advancement of revolutionary diagnosis and treatment techniques inspired from information and communication technologies, which is promising for future nanomedicine and bio-inspired molecular communication applications.