  Molecular communication (MC) is a paradigm that employs molecules as
information transmitters, hence, requiring unconventional transceivers and
detection techniques for the Internet of Bio-Nano Things (IoBNT). In this
study, we provide a novel MC model that incorporates a spherical transmitter
and receiver with partial absorption. This model offers a more realistic
representation than receiver architectures in literature, e.g. passive or
entirely absorbing configurations. An optimization-based technique utilizing
particle swarm optimization (PSO) is employed to accurately estimate the
cumulative number of molecules received. This technique yields nearly constant
correction parameters and demonstrates a significant improvement of 5 times in
terms of root mean square error (RMSE). The estimated channel model provides an
approximate analytical impulse response; hence, it is used for estimating
channel parameters such as distance, diffusion coefficient, or a combination of
both. We apply iterative maximum likelihood estimation (MLE) for the parameter
estimation, which gives consistent errors compared to the estimated Cramer-Rao
Lower Bound (CLRB).
