  This paper proposes a novel imperfect transmitter (TX) model, namely the
membrane fusion (MF)-based TX, that adopts MF between a vesicle and the TX
membrane to release molecules encapsulated within the vesicle. For the MF-based
TX, the molecule release probability and the fraction of molecules released
from the TX membrane are derived. Incorporating molecular degradation and a
fully-absorbing receiver (RX), the channel impulse response (CIR) is derived
for two scenarios: 1) Both TX and RX are static, and 2) both TX and RX are
diffusion-based mobile. Moreover, a sequence of bits transmitted from the TX to
the RX is considered. For the mobile scenario, the probability mass function
(PMF) of the number of molecules absorbed is calculated. Based on the derived
PMF, the average bit error rate (BER) is derived for both scenarios.
Furthermore, a simulation framework is proposed for the MF-based TX, based on
which the derived analytical expressions are validated. Simulation results show
that a low MF probability or low vesicle mobility slows the release of
molecules and reduces the molecule hitting probability at the RX. Simulation
results also indicate the difference between the MF-based TX and an ideal point
TX in terms of the inter-symbol interference (ISI).
