Clock Synchronization for Mobile Molecular Communication Systems

Temporal point-by-point arbitrary waveform synthesis beyond tera sample per second

Arbitrary waveform synthesizers are indispensable in modern information technology, yet electronic counterparts are limited by the speed of analog-to-digital converters to hundreds of GSa/s. While photonic-assisted synthesizers offer potential to surpass this ceiling, scalability and reconfigurability remain challenges. Here, we propose a temporal point-by-point arbitrary waveform synthesizer beyond TSa/s, leveraging an optical temporal Vernier caliper in the photonic synthetic dimension. The system, combining a mode-locked laser and a fiber loop, controls the sampling rate of synthesized waveforms by exploiting a slight detuning between the pulse period and the round-trip delay of the fiber loop. The experiment demonstrates generated waveforms with ultra-high, tunable sampling rate up to 1 TSa/s, an order of magnitude higher than state-of-the-art electronic counterparts. Additionally, the system supports up to 10.4 kilo-points in memory depth. As application examples, the generation of communication waveforms for high-speed wireless communications and linearly chirped microwave waveforms for high-resolution multi-target detection is demonstrated.

Impact of Evanescence Process on Three-Dimensional Sub-Diffusion-Based Molecular Communication Channel

In most of the existing works of molecular communication (MC), the standard diffusion environment is taken into account where the mean square displacement (MSD) of an information molecule (IM) scales linearly with time. On the contrary, this work considers the sub-diffusion motion that appears in crowded and complex (porous or fractal) environments (movement of the particles in the living cells) where the particle's MSD scales as a fractional order power law in time. Moreover, we examine an additional evanescence process resulting from which the molecules can degrade before hitting the boundary of the receiver (RX). Thus, in this work, we present a 3D MC system with a point transmitter (TX) and the spherical RX with the sub-diffusive behavior of an IM along with its evanescence. Furthermore, an IM's closed-form expressions for the arrival probability and the first passage time density (FPTD) are emulated in the above context. Additionally, we investigate the performance of MC by using the concentration-based modulation technique in a sub-diffusion channel. Finally, the considered MC channel is exploited in terms of the probability of detection, probability of false alarm, and probability of error for different parameters such as the reaction rate, fractional power, and radius of the RX.

Evaluation of Non-Coherent Signal Detection Techniques for Mobile Molecular Communication

In recent years, there have been more and more research on molecular communication (MC). Because the deployment of mobile nanomachines may be required in some applications of MC, research on mobile MC has become a trend. The signal detection schemes for static MC are no longer applicable due to the time varying channel impulse response (IR), which is caused by the mobile characteristics of nanomachines. In this paper, a low complexity and non-coherent detection scheme is proposed for mobile scenario, which is based on the energy difference between two adjacent symbols. Most of the existing signal detection methods do not consider inter-symbol interference (ISI). Compared with those methods, the proposed scheme can achieve signal detection utilizing ISI without knowing channel state information (CSI). The bit error rate (BER) performance of the proposed method is investigated under different conditions through simulations. Besides, the influence of mobility features of nanomachines on the signal detection accuracy is also investigated in detail. The simulation results demonstrate that the BER performance of the proposed scheme outperforms the latest signal detection scheme for short-distance mobile MC system with high velocity. Consequently, the detection scheme proposed in this paper can reduce the influence of nanomachines' mobility and has the potential to be used in mobile MC systems.

Interference Alignment Using Reaction in Molecular Interference Channels

Co-channel interference (CCI) is a performance limiting factor in molecular communication (MC) systems with shared medium. Interference alignment (IA) is a promising scheme to mitigate CCI in traditional communication systems. Due to the signal-dependent noise in MC systems, the traditional IA schemes are less useful in MC systems. In this paper, we propose a novel IA scheme in molecular interference channels (IFCs), based on the choice of releasing/sampling times. To cancel the aligned interference signals and reduce the signal dependent noise, we use molecular reaction in the proposed IA scheme. We obtain the feasible region for the releasing/sampling times in the proposed scheme. Further, we investigate the error performance of the proposed scheme. Our results show that the proposed IA scheme using reaction improves the performance significantly.

Analysing scientific publications in the field of mobile information systems using bibliometric analysis

Purpose

This paper aims to present a longitudinal and visualising study using bibliometric approaches to depict the emerging trends and research hotspots within the mobile information system domain.

Design/methodology/approach

Publications included in the Web of Science (WoS) database for 2001–2021 are reviewed and analysed on various aspects through coauthorship, cocitation and co-occurrence analysis. The analyses are conducted using VOSViewer, a scientific visualisation software program.

Findings

Academic publications related to mobile information systems fluctuated at a low level during the initial part of the 21st century and have grown rapidly in number in the past decade. The USA and China are the leading contributors to these publications and hold dominant positions in the obtained collaboration network. Computer science, engineering and telecommunications are the top three research areas in which mainstream mobile information system research occurs. Moreover, medical informatics and health-care science services have gradually become new research hotspots.

Originality/value

This study provides a systematic and holistic account of the developmental landscape of the mobile information system domain. This study provides a good basis for analysing the evolution of research in mobile information systems and may serve as a potential foundation for future research.