Comparing transmission, propagation, and receiving options for nanomachines to measure distance by molecular communication

The ability to design systems of nanomachines may lead to new techniques for future applications. Systems of nanomachines may provide novel mechanisms to interact with cells for medicine, to detect and process waste molecules for environmental applications, or to self-organize nanomachines to manufacture objects. A nanomachine may require information about other nanomachines, such as distance to the other nanomachines, to achieve some applications. Molecular communication is one suitable communication technique for communicating among autonomous nanomachines which are limited in size and capability. In this paper, we consider how a nanomachine can estimate distance information from signal characteristics of a molecular communication. One transceiver nanomachine, T, requests another transceiver nanomachine, R, to transmit a feedback signal. T then estimates distance between T and R from the signal. Several design choices are considered for distance measurement. For transmission, options include releasing a spike of molecules or gradually releasing molecules. For propagation, options include whether or not the environment contains repeaters between T and R. For receiving, options include detecting a threshold concentration of molecules by sampling at a time instant or by capturing molecules over time. The options are compared in terms of range, delay, and accuracy through simulation.