We consider a multi-link diffusion-based molecular communication (MC) system where multiple spatially distributed transmitter (TX)-receiver (RX) pairs establish point-to-point communication links employing the same type of signaling molecules. To exploit the full potential of such a system, an in-depth understanding of the interplay between the spatial link density and inter-link interference (ILI) and its impact on system performance is needed. In this paper, we consider a three-dimensional unbounded domain with multiple spatially distributed point-to-point non-cooperative transmission links, where both the TXs and RXs are positioned on a regular fixed grid. For this setup, we first derive an analytical expression for the channel impulse responses (CIRs) between the TXs and RXs in the system. Then, we derive the maximum likelihood (ML) detector for the RXs and show that it reduces to a threshold-based detector. Moreover, we derive an analytical expression for the corresponding detection threshold which depends on the statistics of the desired signal from the dedicated TX, the statistics of the MC channel, and the statistics of the ILI. Finally, we propose two new performance metrics, namely area rate efficiency (ARE) and area and time rate efficiency (ARTE), suitable for holistically evaluating spatially distributed multi-link MC systems. In particular, ARE and ARTE capture the tradeoff between transmission link density and achievable rate per link and the tradeoff between transmission link density, achievable rate per link, and inter-symbol interference (ISI), respectively. Hence, ARE and ARTE can be exploited to determine the optimal transmission link density for maximizing the throughput of the entire system.

翻译：我们考虑一个基于扩散的多链路分子通信系统，其中多个空间分布的发射器-接收器对采用相同类型的信号分子建立点对点通信链路。为充分利用此类系统的潜力，需深入理解空间链路密度与链路间干扰之间的相互作用及其对系统性能的影响。本文考虑一个三维无界域，其中包含多个空间分布的点对点非协作传输链路，发射器和接收器均置于规则固定网格上。针对该设置，我们首先推导了系统中发射器与接收器之间信道冲激响应的解析表达式。随后推导了接收器的最大似然检测器，并证明其可简化为基于阈值的检测器。同时，我们推导了相应检测阈值的解析表达式，该阈值取决于专用发射器期望信号的统计特性、分子通信信道的统计特性以及链路间干扰的统计特性。最后，我们提出两个新的性能指标——区域速率效率和区域时间速率效率，适用于全面评估空间分布式多链路分子通信系统。具体而言，ARE和ARTE分别捕捉传输链路密度与每链路可达速率之间的权衡，以及传输链路密度、每链路可达速率与符号间干扰之间的权衡。因此，可利用ARE和ARTE确定最优传输链路密度，以最大化整个系统的吞吐量。