Throughout this book, we have introduced the emerging discipline of molecular communication, examining theoretical and implementational aspects. From our survey of the field, there has been tremendous progress towards understanding molecular communication in the past few years. Yet there remains much to be done in order to realize the disruptive potential of this new technology. To conclude our book, we discuss the important future challenges and open problems that remain in this field.

9.1 Toward practical implementation

Certain enabling technologies will be needed to move beyond the current state of knowledge and allow practical communication systems to be built. The following gives an outline of some of these technologies.

• Functional design of molecular communication systems. In Chapter 4, we discussed communication-related functionalities: encoding, decoding, information-carrying, interface, addressing, transport, and guide functionalities. In Chapter 7, we looked at how these functionalities can be implemented. Ideally, molecular communication systems - and, more generally, bio-nanomachines - should be designed in a way that is analogous to existing electronic design techniques, by selecting components that implement given functions, and interfacing them together. However, these design tools do not currently exist.

• Theoretical framework for molecular communication. In Chapters 5 and 6, we discussed the modeling and theoretical analysis of molecular communication systems. In spite of the large volume of work in the past several years, there remain many open problems.