On the Coexistence of Nano Networks: Sensing Techniques for Molecular Communications

Molecular communication is an emerging communication paradigm for biological nanomachines. The fast growth of molecular communication techniques in varieties of nanomedical applications can result in scenarios where there are more than one nanonetwork working in a biological environment. On the other hand, possible limitation on the type of molecules, used as information carriers, can result in coexistence problems in co-located molecular communication systems. This paper studies the coexistence problem of two nanonetworks, where one of the nanonetworks is able to intelligently sense the molecular channel and use the channel opportunistically for its own transmission. The sensing nanonetwork measures the concentration of molecules as a criterion to detect the channel white spaces by using a molecular energy detection scheme. When the molecular channel is available, the associated transmitter sends its information using the same carrier molecules. Depending on the availability of timing information at the sensing nanodevice, two synchronous and asynchronous sensing mechanisms are provided based on the likelihood ratio test as the optimal detection method. We also provide numerical simulations of the proposed sensing mechanisms to show that the coexistence of multiple molecular communications is feasible and can be efficiently implemented in nanonetworks.