Before revision:  In RSK, the transmitter uses different chemical reactions to generate different time-varying functions of concentration of signalling molecules to represent different transmission symbols . We consider the problem of demodulating the RSK symbols assuming that the transmitter and receiver are synchronised. We assume the receiver consists of receptors and signalling molecules may react with these receptors to form ligand-receptor complexes.
After revision:  In RSK, the transmitter uses different chemical reactions to generate different time-varying functions of concentration of signalling molecules to represent different transmission symbols , and the receiver consists of receptors and signalling molecules may react with these receptors to form ligand-receptor complexes.