  Diffusive molecular communication (DMC) is one of the most promising
approaches for realizing nano-scale communications in biological environments
for healthcare applications. In this paper, a DMC system in biological
cylindrical environment is considered, inspired by blood vessel structures in
the body. The internal surface of the cylinder boundary is assumed to be
covered by the biological receptors which may irreversibly react with hitting
molecules. Also, information molecules diffusing in the fluid medium are
subject to a degradation reaction and flow. The concentration Green's function
of diffusion in this environment is analytically derived which takes into
account asymmetry in all radial, axial and azimuthal coordinates. Employing
obtained Green's function, information channel between transmitter and
transparent receiver of DMC is characterized. To evaluate the DMC system in the
biological cylinder, a simple on-off keying modulation scheme is adopted and
corresponding error probability is derived. Particle based simulation results
confirm the proposed analysis. Also, the effect of different system parameters
on the concentration Green's function are examined. Our results reveal that the
degradation reaction and the boundary covered by biological receptors may be
utilized to mitigate intersymbol interference and outperform corresponding
error probability.
