A Molecular Spatio-Temporal Modulation Scheme for MIMO Communications

In molecular communication via diffusion (MCvD), information is conveyed by diffusing molecules. MCvD enjoys high energy efficiency but suffers from low date rates due to the long tail of the channel impulse response. To this end, the multiple-input multiple-output (MIMO) technique has been introduced to MCvD. However, the inter-symbol interference (ISI) and inter-link interference (ILI) deteriorate the bit error rate (BER) performance of MIMO MCvD systems. In this paper, a novel molecular modulation scheme, called molecular type permutation shift keying in the spatio-temporal domain, is proposed for MIMO MCvD systems to improve the BER performance by combating ILI and ISI. A low-complexity detector without requiring channel impulse response information is proposed. Furthermore, a complementary coding scheme that can effectively reduce ILI is designed. Additionally, the BER upper bound is analyzed. Numerical simulations on BER corroborate the analysis and show that the proposed scheme is a promising multi-molecule modulation alternative, which outperforms the existing MIMO MCvD modulation schemes.