  In this paper, we study the bidirectional/two-way relaying of molecular
communication and propose a relaying scheme with two time slots. Compared to
the four-time-slot and three-time-slot schemes, the proposed two-time-slot
scheme improves the throughput by a significant extent by allowing the end
nodes to transmit simultaneously at the very first time slot. In contrast to
the existing techniques, the proposed scheme employs a homogeneous molecular
communication for bidirectional relaying where all the nodes (i.e., end nodes
and relay node) are allowed to operate on the same type of molecule instead of
utilizing different types of molecule for different nodes. As a result, this
proposal of homogeneous molecular relaying remarkably improves the resource
reuse capability. This paper generically characterizes the transmission and
detection strategies of the proposed scheme. Moreover, we derive the analytical
bit error probabilities for the multiple access and broadcast phases and
present the end-to-end bit error probability of the proposed scheme. It's
noteworthy that we take it into account the effect of molecular interference in
the theoretical derivations. Extensive simulation is carried out, and it is
shown that simulation results match very well with the derived theoretical
analysis.
