A basic property of any diffusion-based molecular communication system is the geometry of the enclosing container. In particular, the geometry influences the system's behavior near the boundary and in all existing modulation schemes governs receiver design. However, it is not always straightforward to characterize the geometry of the system. This is particularly the case when the molecular communication system operates in vitro, where the geometry may be complex or dynamic. In this paper, we propose a new scheme-called equilibrium signaling-which is robust to uncertainties in the container geometry. In particular, receiver design only depends on the relative volumes of the transmitter or receiver, and the entire container. Our scheme relies on reversible reactions in the transmitter and the receiver, which ensure the existence of an equilibrium state into which information is encoded. In this case, we derive near optimal detection rules and develop a simple and effective estimation method to obtain the container volume. We also show that equilibrium signaling can outperform classical modulation schemes, such as concentration shift keying, under practical sampling constraints imposed by biological oscillators.

中文翻译：

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平衡信号：分子通信对几何不确定性的鲁棒性

任何基于扩散的分子通讯系统的基本特性是封闭容器的几何形状。特别是，几何形状会影响系统在边界附近的行为，并且在所有现有调制方案中都控制着接收机设计。然而，表征系统的几何形状并不总是那么简单。当分子通信系统在体外运行时尤其如此，其中几何形状可能是复杂的或动态的。在本文中，我们提出了一种称为平衡信号的新方案，它对容器几何形状的不确定性具有鲁棒性。特别是，接收器设计仅取决于发射器或接收器以及整个容器的相对体积。我们的方案依赖于发射器和接收器中的可逆反应，这确保了信息被编码到的平衡状态的存在。在这种情况下，我们推导出接近最优的检测规则并开发一种简单有效的估计方法来获得容器体积。我们还表明，在生物振荡器施加的实际采样约束下，平衡信号可以优于经典调制方案，例如浓度偏移键控。