Adaptive code width protocol for mitigating intersymbol interference in diffusion-based molecular communication with mobile nodes

Molecular communication (MC) is a promising technique to enable the communication among nanomachines for various applications in healthcare industry such as targeted drug delivery. In this paper, we focus on the intersymbol interference (ISI) problem in diffusion-based MC. In this kind of communication, the ISI is notably influenced by communication distance and code width. On this basis, we propose an adaptive code width (ACW) protocol to mitigate the intersymbol interference. In this protocol, a 'distance feedback' is used to measure the communication distance. We adopt a signal attenuation model to accomplish this task. According to the measured distance, the transmitter can adapt the modulation using an appropriate code width in order to mitigate the ISI. Moreover, the ACW protocol improves the transmission efficiency when communication distance is short and ISI does not affect bit error rate. Finally it is verified that this protocol is feasible to control the ISI at a low level even when the channel varies due to the mobility of the transceivers.