Enhanced Molecular Type Permutation Shift Keying for Molecular Communication

Molecular type permutation shift keying (MTPSK) performs information transmission by the full permutations of different molecular types, which can combat the severe inter-symbol interference (ISI) in molecular communications. This letter proves that the achievable rate (AR) of MTPSK is restricted by its modulation principle and as a remedy proposes an enhanced (E-)MTPSK to improve the AR by conveying information through the permutations of partial molecular types. The exact and approximate ARs are derived for E-MTPSK, MTPSK, and molecular shift keying. Numerical results on ARs and bit error rates reveal the trade-off between the AR and ISI-mitigation capability, and that the proposed scheme can outperform the prevalent modulation counterparts.