On the Impact of Transposition Errors in Diffusion-Based Channels

Transposition errors fundamentally undermine reliability and capacity in molecular communication, when individual particles are used for information encoding. Recently, several channel coding techniques have been proposed for mitigating the transposition effect. The presented techniques show promising results for diffusion-based channels with drift. However, so far no performance evaluation has been carried out for diffusionbased channels without drift, although in this case, transpositions are more prominent. In this work, we first derive an analytical expression for the uncoded bit error probability due to transpositions. Then, we compare the uncoded and coded error performance over diffusion-based channels with and without drift by means of computer simulations. The results reveal that for diffusion-based channels without drift a transmission with reasonable reliability can only be achieved by introducing a guard time between the codewords. This research lays the foundation for future development of strategies to mitigate transpositions in pure diffusion-based channels.