ISI Mitigation Techniques in Molecular Communication

Abstract

Molecular communication is a new field of communication where molecules are used to transfer information. Among the proposed methods, molecular communication via diffusion (MCvD) is particularly effective. One of the main challenges in MCvD is the intersymbol interference (ISI), which inhibits communication at high data rates. Furthermore, at the nano scale, energy efficiency becomes an essential problem. Before addressing these problems, a pre-determined threshold for the received signal must be calculated to make a decision. In this paper, an analytical technique is proposed to determine the optimum threshold, whereas in the literature, these thresholds are generally calculated empirically. Since the main goal of this paper is to build an MCvD system suitable for operating at high data rates without sacrificing quality, new modulation and filtering techniques are proposed to decrease the effects of ISI and enhance energy efficiency. As a transmitter-based solution, a modulation technique for MCvD, molecular transition shift keying (MTSK), is proposed in order to increase the data rate via suppressing the ISI.Furthermore, for energy efficiency, a power adjustment technique that utilizes the residual molecules is proposed. Finally, as a receiver-based solution, a new energy efficient decision feedback filter (DFF) is proposed as a substitute for the decoders such as minimum mean squared error (MMSE) and decision feedback equalizer (DFE). The error performance of DFF and MMSE equalizers are compared in terms of bit error rates, and it is concluded that DFF may be more advantageous when energy efficiency is concerned, due to its lower computational complexity.DRAFT

Molecular Channel Fading Due to Diffusivity Fluctuations

“…Similar to previous research [14], [15], we also consider a number of previous symbols that can accurately represent ISI (i.e., 10 symbols). The ISI for a OOK system with a constant symbol period T s can generally be expressed as the sum of interference from M previous symbols:…”

Comparative Analysis of Three Dimensional Channel Models in Molecular Communication via Diffusion

“…Numerical results show that the proposed MOCSK technique has lower probability of error as compared to CSK and MOSK techniques. In [14], an energy efficient ISI mitigation technique for MCvD channel is proposed. Three different approaches are considered for energy efficiency problem in the MCvD system.…”

“…The second approach reported in [14], introduces a technique to determine the optimal detection threshold values that minimize the bit error rate. If there is a slight change in the system parameters such as temperature, distance, diffusion co-efficient, radius of the receiver etc, then it needs to repeat the calculation of threshold.…”

“…The Power Adjustment (PA) is the third approach reported in [14], utilizes the residue molecules from previous symbol and also reduces the energy consumption in the transmitter node. For sending consecutive symbols '1', the same amount of messenger molecules is emitted for each symbol.…”

Molecular Communication in Nanonetworks

“…In MC channel, ISI is the main interference source and has a significant impact on the performance of modulation [66]. Therefore, effective ISI mitigation techniques are worthy of attention.…”