Analog Network Coding in Molecular Communications: A Practical Implementation

In a communication scenario with two transceivers (TRXs) and one relay, four time slots are required to communicate one packet in each direction if the relay uses a store-and-forward technique. With digital network coding (NC) three time slots are needed, and if analog netwok coding (ANC) is used, only two time slots are necessary. Communication systems with a low transmission rate such as molecular communication (MC) systems can especially benefit from the traffic reduction of ANC. The available literature only considers theoretical studies on the application of NC in MC nanonetworks. In this paper, we present for the first time a macroscale MC testbed for ANC to fill the gap between theory and practice. By using our testbed, we demonstrate the influence of time synchronization on the bit error ratio (BER) performance of the network coded MC system. We also study the influence of the bit sequence length on the error ratio of the system. Furthermore, we implemented duplex NC and demonstrated that the error ratios of half duplex and full duplex NC are close, but full duplex NC results in a time gain of up to
$(n-1)$
time slots for a bit sequence length n.