Mobile molecular communication (MC) attracts much attention in recent years where mobile nanomachines exchange information using molecules. In this paper, we consider a diffusion-based mobile MC system consisting of a pair of diffusive nanomachines. Due to the Brownian motion of nanomachines, the communication distance between the transmitter and the receiver is dynamic. Thus, the channel impulse response (CIR) is a stochastic process. The stochastic CIR brings the difficulty in the detection process. Contrast to the common static MC characterized by the deterministic CIR, in a mobile MC system, the receiver needs to estimate the dynamic distance for CIR reconstruction and detection threshold setting at each bit interval, which achieve high computational complexity. To tackle these difficulties, a new detection technique for mobile MC is proposed in this paper. It is unnecessary to estimate the dynamic communication distance at each bit interval. Instead, the receiver estimates the initial distance between it and the transmitter. The estimated initial distance can be used to reconstruct the statistical characteristics of CIR, setting detection threshold for all the bit intervals in advance. To achieve this goal, a novel two-step scheme based on maximum likelihood (ML) is proposed to estimate the initial distance. In the first step, the transmitter releases some molecules as a pilot signal before the information bits transmission. Then the receiver estimates releasing distance by observations of received signal. In the second step, the estimated value obtained in the previous step is used to estimate the initial distance by ML estimation. The performances of proposed two-step scheme and the detection technique are evaluated via particle-based simulation of the Brownian motion.

中文翻译：

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扩散移动分子通信的初始距离估计和信号检测。

近年来，移动分子通信（MC）引起了人们的广泛关注，其中移动纳米机器使用分子来交换信息。在本文中，我们考虑由一对扩散纳米机组成的基于扩散的移动MC系统。由于纳米机器的布朗运动，发射器和接收器之间的通信距离是动态的。因此，信道冲激响应（CIR）是随机过程。随机CIR给检测过程带来困难。与以确定性CIR为特征的普通静态MC相比，在移动MC系统中，接收机需要估计动态距离，以在每个位间隔进行CIR重建和检测阈值设置，从而实现较高的计算复杂性。为了解决这些困难，提出了一种新的移动MC检测技术。不必估计每个位间隔的动态通信距离。相反，接收器估计其与发送器之间的初始距离。估计的初始距离可用于重建CIR的统计特性，并预先为所有位间隔设置检测阈值。为了实现这个目标，提出了一种基于最大似然（ML）的新颖的两步方案来估计初始距离。第一步，发送器在信息位传输之前释放一些分子作为引导信号。然后，接收器通过观察接收信号来估计释放距离。在第二步骤中，在前一步骤中获得的估计值用于通过ML估计来估计初始距离。