  Diffusion-based molecular communication (MC) systems experience significant
reliability losses. To boost the reliability, an MC scheme where multiple
receivers (RXs) work cooperatively to decide the signal of a transmitter (TX)
by sending the same type of molecules to a fusion center (FC) is proposed in
this paper. The FC observes the total number of molecules received and compares
this number with a threshold to determine the TX's signal. The proposed scheme
is more bio-realistic and requires relatively low computational complexity
compared to existing cooperative schemes where the RXs send and the FC
recognizes different types of molecules. Asymmetric and symmetric topologies
are considered, and closed-form expressions are derived for the global error
probability for both topologies. Results show that the trade-off for simplified
computations leads to a slight reduction in error performance, compared to the
existing cooperative schemes.
