Molecular circuits for decoding frequency coded signals in nano-communication networks

A key research question in the design of molecular nano-communication networks is how the information is to be encoded and decoded. One particular encoding method is to use different frequencies to represent different symbols. This paper will investigate the decoding of such frequency coded signals. To the best of our knowledge, the current literature on molecular communication has only used simple ligand–receptor models as decoders and the decoding of frequency coded signals has not been studied. There are two key issues in the design of such decoders. First, the decoder must exhibit frequency selective behaviour which means that encoder symbol of a specific frequency causes a bigger response at the decoder than symbols of other frequencies. Second, the decoder must take into account inter-symbol interference which earlier studies on concentration coding have pointed out to be a major performance issue. In order to study the design of decoder, we propose a system of reaction–diffusion and reaction kinetic equations to model the system of encoder, channel and decoder. We use this model to show that enzymatic circuit of a particular inter-connection has frequency selective properties. We also explore how decoder can be designed to avoid inter-symbol interference.