A Molecular Communication-Based Simultaneous Targeted-Drug Delivery Scheme

This paper considers simultaneous drug-delivery (SDD) in molecular communication-based (MC-based) targeted drug-delivery systems. In a realistic scenario, the drug-carrying nanomachines are randomly placed close to the infected site. Due to the random propagation delays in the MC channel, the drugs from multiple drug-carrying nanomachines may, therefore, not arrive simultaneously at the infected site, leading to low efficacy and resulting in drug-delivery-time errors. To overcome this error and to administer the drugs simultaneously at the infected site, we use an internal controller nanomachine to control the release times of the drug-carrying nanomachines, with consideration of the propagation delay, to achieve SDD. In this regard, we propose two SDD schemes, namely, the direct trigger estimate SDD (DTE-SDD) scheme and the indirect trigger estimate SDD (iDTE-SDD) scheme. The difference between these schemes is that in the iDTE-SDD scheme, to estimate the propagation delay, the internal controller nanomachine depends on the drug-carrying nanomachines, while in the DTE-SDD scheme, it does not. Furthermore, to study the errors theoretically, we derive the analytical model of delivery-time error, and this is validated with simulation results. We perform intensive evaluations to understand the system's behavior under different channel conditions, such as the number of molecules released and the distance. The simulation results highlight the proposed scheme's energy efficiency and robustness to the large propagation delay, reducing the delivery-time error to improve the accuracy of the SDD.