Performance Analysis of Signal Detection for Amplify-and-Forward Relay in Diffusion-Based Molecular Communication Systems

Molecular communication (MC) is a promising technique of using molecules to realize communication between nanomachines for Internet of Bio-Nano Things in the body area nanonetwork. Due to the properties of diffusion and the attenuation of molecular transmission, the diffusion-based MC confronts with challenges in terms of the communication range and the signal detection accuracy. To extend the coverage, the intermediate nanomachine is deployed as relay between transmitter and its intended receiver. In this article, amplify-and-forward (AF) relaying is researched, and the performance under diverse signal detection schemes is analyzed, including mean square error (MSE) detection, maximum a posteriori probability detection, minimum error probability (MEP) detection under stationary fluid environment, and the MEP detection with a drift velocity simulation. The key parameters, such as the number of released molecules, receiving radius, and the relay position, influencing on the AF relaying performance under different detection methods are explored. The simulation results show that the MEP detection can achieve the best performance gain for the AF relay with a drift velocity channel. In particular, when the number of released molecules is 500, the gain is up to 35 dB.