Molecular Communications Enhanced by Time-Varying Electric Field

In this work, we propose applying a time-varying electric field to a time-slotted molecular communication system with ionized message particles to combat inter-symbol interference (ISI) and enhance the transmission performance. Firstly, the solution to the Nernst-Planck equation, which describes the motion of ions under the electric field, is derived. With the derived solution, the bit error probability (BEP) and the receiver operating characteristic (ROC) curve are analyzed. Then, the time-varying electric field is optimized by the proposed algorithms to respectively minimize the error probability (MinEP), maximize the signal-to-interference ratio (MaxSIR), and maximize the sensing probability (MaxSP). For solving the MinEP and MaxSIR problems, algorithms based on the approximate gradient descent method are proposed. In addition, an efficient algorithm is proposed for solving the MaxSP problem. The proposed MinEP and MaxSIR schemes are shown to effectively mitigate ISI, and the proposed MaxSP scheme delivers the near-optimal performance with low complexity, demonstrating that the performance of molecular communications can be significantly enhanced by applying the time-varying electric field.