  The emerging in vivo communication and networking system is a prospective
component in advancing healthcare delivery and empowering the development of
new applications and services. In vivo communications is based on networked
cyber-physical systems of embedded devices to allow rapid, correct and cost-
effective responses under various conditions. This chapter presents the
existing research which investigates the state of art of the in vivo
communication. It focuses on characterizing and modeling the in vivo wireless
channel and contrasting it with the other familiar channels. MIMO in vivo is
also of cencern in this chapter since it significantly enhances the performance
gain and data rates. Furthermore, this chapter addresses in vivo
nano-communication which is presented for medical applications to provide fast
and accurate disease diagnosis and treatment. Such communication paradigm is
capable of operating inside the human body in real time and will be of great
benefit for medical monitoring and medical implant communications.
Consequently, propagation at the Terahertz (THz) frequency must be well
understood as it is considered the most promising band for electromagnetic
nano-communication models.
