Transmitter localization in vessel-like molecular communication channels is a fundamental problem with potential applications in healthcare. Existing analytical solutions either assume knowledge of emission time or require multiple closely spaced receivers, which limits their applicability in realistic scenarios. In this letter, we propose a simple closed-form approximation that exploits the temporal variance of the received molecular signal to estimate the distance between the transmitter and the receiver without emission time information. The method is derived from a Gaussian approximation of the received signal near its peak and gives an explicit variance-distance relation. Simulation results in physically relevant capillary vessel scale show that the proposed method achieves distance prediction with error on the order of 1%.

翻译：血管状分子通信信道中的发射机定位是一个具有潜在医疗应用价值的基础问题。现有解析解要么需要已知发射时间，要么要求多个紧密排列的接收机，这限制了其在现实场景中的适用性。本文提出一种简单的闭式近似方法，利用接收分子信号的时间方差来估计发射机与接收机之间的距离，无需发射时间信息。该方法基于接收信号峰值附近的高斯近似推导，给出了显式的方差-距离关系。在生理相关毛细血管尺度下的仿真结果表明，该方法可实现误差量级为1%的距离预测。