Propagation delay models in bio-inspired nanonetworks

ABSTRACT: Nanomachines are devices that are made up of nanoscale components. By themselves, nanomachines can perform only simple tasks. To achieve more complex tasks, networks of manomachines or nanonetworks are formed. Molecular communication is a biocompatible, bio-inspired alternative to traditional electromagnetic communication in nanonetworks. In molecular communication, molecules can be considered as information packets. Free diffusion based molecular communication requires no external energy and is the most basic information transport mechanism being considered for nanonetworks. This form of communication however is slow due to the random walk of the particles and the information packets can also be delivered out of order to the destination. These issues present challenges to design and implementation of molecular communication based nanonetworking protocols. While there are significant studies that address physical layer aspects of molecular communication, there is relatively less work in the link layer. In particular, modeling of channel delays or sojourn times of molecule-packets that arrive at a nanomachine is required for queueing theoretic analyses. To this end, simulations are performed to measure the propagation times of molecules between a given source and a destination in both bounded one- and twodimensional spaces and unbounded one-dimensional spaces. Here, one-dimensional settings correspond to molecular communication that take place in very thin capillaries and two-dimensional settings correspond to communication in junctions with small widths, negligible heights or on membranes. There are no closed-form formulas for the delay distribution of freely diffusing particles in arbitrary, bounded environments. The delay measurements in bounded settings are fitted to well-known distributions that are commonly used in modeling time to complete a task. The fits can be used to generate arrival times of molecule-packets at a node. This study is expected to contribute to the analysis of link layer protocols and workload models being considered for nano communication networks. Keywords: Distribution Fitting, Free Diffusion, Molecular Communication, Nanonetworks. …………………………………………………………………………………………………………………………