Molecular Communications Based on Probabilistic Constellation Shaping: Optimal Detection and Performance Analysis

Probabilistic constellation shaping (PCS) has been shown to be effective for molecular communications. Reed-Solomon coded PCS (RS-PCS) is one of the promising realizations proposed recently that combines PCS and channel coding through a parallel transmitter structure. However, the current receiver designed for RS-PCS often misdetects the intra-sequence interference (IEI), resulting in a performance gap. To address this shortcoming, we propose two performance-enhanced detectors. The first one combines increase detection algorithm (IDA) and RS-PCS to enhance the accuracy of IEI detection. The second one is the joint maximum-likelihood detection (joint ML) that has the optimal performance in terms of bit error rate (BER), which is derived theoretically. Simulation results verify their better performance than existing RS-PCS schemes.