  Molecular communication via diffusion (MCvD) is considered as one of the most
feasible communication paradigms for nanonetworks, especially for
bio-nanonetworks which are usually in water-rich biological environments. Two
effects that deteriorates the signal in MCvD are noise and inter-symbol
interference (ISI). The expected channel impulse response of MCvD has a long
and slow attenuating tail due to molecular diffusion which causes ISI and
further limits the slow data rate of MCvD. The extent that ISI and noise are
suppressed in an MCvD system determines its effectiveness, especially at a high
data rate. Although ISI-suppression approaches have been investigated, most of
them are addressed as non-essential parts in other topics, such as signal
detection or modulation. Furthermore, most of the state-of-the-art
ISI-suppression approaches are performed by subtracting the estimated ISI from
the total signal. In this work, we investigate ISI-suppression from a new
perspective of filters to filter ISI out without any ISI estimation. The
principles for a good design of ISI-suppression filters in MCvD are
investigated. Based on the principles, an ISI-suppression filter with good
anti-noise capability and an associated signal detection scheme is proposed for
MCvD scenarios with both ISI and noise. We compare the proposed scheme with the
state-of-the-art ISI-suppression approaches. The result manifests that the
proposed ISI-suppression scheme could recover signals deteriorated severely by
both ISI and noise, which could not be effectively detected by the
state-of-the-art ISI-suppression approaches.
