Simulating the performance of SW-ARQ schemes within molecular communications

• 5 SW-ARQ Schemes are proposed that benefit diffusion-based molecular communications.
• The Performance is determined by average time and energy utilisation.
• Scheme 1 benefits communication between low power adjacent Nano-machines.
• Schemes 2 and 3 exhibit further performance benefits for longer range or higher power applications.
• Schemes 4 and 5 benefit diffusion molecular communications with unknown or variable channels.

This paper provides results on an investigation concerning the application of five tailored Stop-and-Wait Automatic Repeat reQuest (SW-ARQ) schemes to a diffusion based molecular communication system. Each scheme is numerically simulated and evaluated to determine its performance with regards to average time cost and energy consumption. It is shown that all five schemes are beneficial depending upon the application scenario. Scheme 1 is the best choice for adjacent communications although, if a slightly higher energy budget can be afforded, schemes 2 and 3 will provide better performance than scheme 1 as the communication distance increases. Schemes 4 and 5 are designed to benefit scenarios with either a varying channel or for a channel with unknown parameters although will also benefit a static channel if again, further system energy can be utilised. This optimisation and trade-off between time and energy requirement for a complete successful transmission will become more important in future applications involving molecular communications where energy efficiency is a design consideration.