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

Molecular communication (MC) is a promising paradigm which utilizes molecules to implement communication among nano-machines. Due to short transmit range, amplify-and forward (AF) relay is used to extend the communication distance and achieve a reliable remote communications in diffusion-based MC systems. In this paper, an AF relay strategy in diffusion based MC systems is researched, in which the capture probability function is formulated by searching for the essence of AF, and the distribution of the number of molecules received at the receiver is modeled as an approximate normal distribution. The impact of AF relay location and the signal detection threshold on the system performance are exploited, and the optimal signal detection threshold is derived by using the maximum a posteriori probability. The simulation results show that the proposed AF relay strategy can effectively improve the system performance, and the optimal relay location can achieve the best performance.