  We consider a molecular communication system comprised of a transmitter, an
absorbing receiver, and an interference source. Assuming amplitude modulation,
we analyze the dependence of the bit error rate (BER) on the detection
interval, which is the time within one transmission symbol interval during
which the receiver is active to absorb and detect the number of
information-carrying molecules. We then propose efficient algorithms to
determine the optimal detection interval that minimizes the BER of the
molecular communication system assuming no inter-symbol interference (ISI).
Simulation and numerical evaluations are provided to highlight further insights
into the optimal results. For example, we demonstrate that the optimal
detection interval can be very small compared to the transmission symbol
interval. Moreover, our numerical results show that significant BER
improvements are achieved by using the optimal detection interval for systems
without and with ISI.
