The Internet of nano things (IoNTs) envisions thousands of nanomachine nodes that sense, compute, actuate and communicate at the nanoscale. With the development of nanotechnology, DNA technology, a promising way to achieve precise manipulation in the microscopic world, have shown their potential as multiple nanomachine nodes within IoNTs, such as sensing and actuation. However, current DNA nanomachine research mostly focuses on solutions for specific diseases and lacks a generalizable and universal design. This will not only undoubtedly hinder the realization of DNA-based IoNTs but also limit the development of DNA nanomachine. In recent years, researchers has begun to realize this problem and proposed some more integrated and versatile DNA nanomachine designs, incorporating with logic and communication functions. Among these, the integration of molecular communication gives DNA nanomachine the potential to realize IoNTs, making it more promising for future applications. Therefore, this review comprehensively sorts out recent researches of DNA nanomachine over the past decade and discusses them from the perspective of IoNTs systems. In detail, we review and analyze existing DNA nanomachine researches from communication fundamental to various nodes within the network (computing, sensing, actuation, etc.), introduce the technology behind and evaluate the performance of DNA nanomachines. Finally, we present the development prospects of DNA-based IoNTs and discuss the challenges. We hope that this review will help inspire the design of more integrable DNA nanomachines and promote the progress of both DNA nanomachine and IoNTs research.

The advancement of nanotechnology has enabled the deployment of medical nanonetworks within the human body, further accelerated by progress in terahertz communication technologies and nanonetwork routing protocols. However, nanonodes may move in dynamic environments due to environmental influences or self-propulsion mechanisms, posing significant challenges to routing protocol design. To address this, we propose a dynamic routing protocol for nanonetworks that integrates real-time velocity vectors to account for time-varying node positions. During relay node selection, key factors such as candidate nodes' velocity vectors are comprehensively evaluated to determine the optimal relay for next-hop transmission. To ensure efficient data exchange among multiple nodes, we design a time-division multiple access (TDMA)-based media access control (MAC) protocol to prevent packet collisions and losses. The protocol assigns distinct transmission and reception time slots to different node types and implements a countdown mechanism to manage channel access and eliminate conflicts. Numerical and simulation results demonstrate that the proposed protocol significantly outperforms benchmark protocols, achieving notable improvements in both time and energy efficiency.

Molecular communication (MC) is a prominent technique within the Internet of Bio-Nano Things (IoBNT), which aims to interconnect artificial and biological devices for pioneering healthcare applications. Despite its rapid advancements in theoretical study, the experimental development of MC is still in the infancy stage, and most existing testbeds require intruding hardware into the channel during the signal detection process, potentially harming the organism. Against this background, the noninvasive interface across the internal and external information exchange of organisms is of great necessity. Specifically, this work adopts a capacitive sensing mechanism to recover information from the sensed chemical signals. Our testbed demonstrates a notably higher transmission rate than previously reported noninvasive MC approaches, underscoring its potential to advance IoBNT research.

This paper establishes a molecule harvesting transmitter (TX) model in molecular communication (MC). In particular, we consider that molecules are encapsulated in vesicles generated within the TX and released from the TX through membrane fusion process. We also consider that the TX membrane is covered by heterogeneous receptors of varying sizes and at arbitrary locations, where the receptors can absorb the released molecules once the molecules hitting any of the receptor. Assuming that the vesicle generation follows a jump process, with each vesicle generated at distinct time instants, and assuming a transparent receiver (RX), we calculate the molecule release rate, the expected fraction of absorbed molecules at the TX, and the received signal at the RX. All obtained analytical expressions are functions of all receptors’ locations and sizes, and are validated by particle-based simulations. Our numerical results indicate that evenly distributed receptors on the TX membrane absorb more molecules than randomly distributed receptors or a single receptor. Furthermore, inspired by the biological phenomenon that cells can regulate their release of new molecules by interacting with the molecules that are already present in the environment, we incorporate a negative feedback mechanism (NFM) at the TX. This mechanism utilizes the number of molecules absorbed by the TX as a criterion to determine if the TX should stop releasing additional molecules. We then derive the closed-form expression for the expected fraction of recyclable molecules for a single emission. Here, the pool of recyclable molecules comprises both the molecules that remain unreleased by the TX due to NFM and those that are absorbed back by the TX. Our numerical results demonstrate that incorporating NFM can reduce inter-symbol interference (ISI) while maintaining the same peak received signal as without NFM. Additionally, our results show that TXs incorporating both molecule harvesting and NFM can achieve a higher energy efficiency and lower error probability than TXs employing only molecule harvesting or neither functionality.

This paper investigates a wireless powered internet of things (IoT) network, where a hybrid access point (HAP) performs both wireless energy transfer (WET) and wireless information transfer (WIT). Specifically, the HAP charges IoT devices via WET and collects their updated information via WIT. To ensure the information freshness, an adaptive cooperative transmission scheme is proposed, where information packets of devices are transmitted either directly or cooperatively with the assistance of another device. To this end, an expected weighted sum of age of information (EWSAoI) minimization problem is formulated to adaptively determine the best device pairs for cooperative transmissions, and schedule the corresponding transmission, i.e., WET, direct WIT, or cooperative WIT. Leveraging the Lyapunov optimization framework, a low-complexity adaptive scheduling scheme is proposed, wherein the device pairing or information transmissions are determined based on the instantaneous AoI and energy status of IoT devices. Furthermore, to reduce signalling overhead, a two-timescale scheduling scheme is proposed, wherein a matching algorithm is incorporated to pair devices for cooperative transmission in a large timescale while the adaptive transmission of energy and information are executed in a small timescale. Simulation results validate that adaptive cooperative scheduling scheme effectively reduces the AoI with low system overhead, and the gain approaches to 43.3%, compared with non-cooperative scheme.

Involving proper boundaries is an important aspect of molecular communication, especially when considering it as a potential candidate for intra-body communication. Inspired by the massive cellular environments, this paper proposes a novel approach to model the channel for a diffusive molecular communication (DMC) system in a bounded spherical environment. Specifically, this spherical boundary is made up of a reflecting and absorbing portion, whose property depends on whether it is covered by absorbing receptors (ARs). To obtain an accurate channel impulse response (CIR), we employ the homogenization technique to convert the mixed Dirichlet-Neumann boundary into a Robin boundary. Assuming these ARs with the same size and uniform distribution, we derive a valid CIR expression for the bounded DMC system with arbitrary sizes and numbers of ARs. Numerical results based on the particle-based simulation validate our analysis.

Affine frequency division multiplexing (AFDM) is an emerging multicarrier waveform that offers a potential solution for achieving reliable communications over time-varying channels. This paper proposes two maximum-likelihood (ML) estimators of symbol time offset and carrier frequency offset for AFDM systems. One is called joint ML estimator, which evaluates the arrival time and carrier frequency offset by comparing the correlations of samples. Moreover, we propose the other so-called stepwise ML estimator to reduce the complexity. Both proposed estimators exploit the redundant information contained within the chirp-periodic prefix inherent in AFDM symbols, thus dispensing with any additional pilots. To further mitigate the intercarrier interference resulting from the residual frequency offset, we design a mirror-mapping-based scheme for AFDM systems. Numerical results verify the effectiveness of the proposed time and carrier frequency offset estimation criteria and the mirror-mapping-based modulation for AFDM systems.

In this article, we study a previously overlooked work of designing the constellation for concentration shift keying (CSK) in diffusion-based molecular communication (MC) systems, considering the adverse effects of signal-dependent noise and intersymbol interference (ISI). Against this background, the conventionally used uniform constellation strategy is no longer the optimal choice for CSK. Considering the discrete nature of messenger molecules, the constellation design of CSK is essentially a nonlinear integer programming problem. However, due to the nonconvexity of the goal function, general convex optimization methods cannot be easily employed. To solve the aforementioned problem, a novel CSK strategy with a brute-force search algorithm is proposed to obtain the optimal constellation numerically. Moreover, a low-complexity search algorithm that provides new insight into reducing the complexity of MC systems is further presented. Specifically, we theoretically derive the optimal threshold and employ a maximum likelihood detector that effectively minimizes the average symbol error rate (SER) by leveraging the knowledge of ISI at the receiver. Finally, we can obtain a fitted equation for the nearly optimal constellation points under specific channel parameters, attaining the SER performance similar to the optimal one, while the search complexity is much lowered.

In this paper, we employ a reconfigurable intelligent surface (RIS) to boost the single-carrier frequency-domain equalization (SC-FDE) transmission for both single- and multi-antenna broadband wireless communications. Different from the existing RIS-SC-FDE schemes that use an RIS to harvest cyclic delay diversity with a limited beamforming gain, our advanced schemes unlock the potential of the RIS in passive beamforming to maximize the receive signal-to-noise ratio. Concerning the high complexity issue, a low-complexity minorization-maximization (MM) method, which leads to a closed-form solution in each iteration, is developed for the RIS beamforming optimization problem. Finally, simulation results show that the proposed RIS-SC-FDE with the MM-based beamforming significantly outperforms the existing counterparts in terms of bit error rate.

In this paper, we redesign the concentration shift keying (CSK) constellation design for diffusion-based molecular communication systems, where both signal-dependent noise and inter-symbol interference (ISI) are considered. The conventionally used uniform constellation strategy is no longer the optimal choice when signal-dependent noise exists. Against this background, a novel CSK constellation strategy with the maximum likelihood detector is presented by minimizing the symbol error rate (SER) with statistical ISI knowledge. The well-matched analytical and simulated results in terms of SER demonstrate the effectiveness of our proposed CSK constellation design.

Molecular communication is attractive to the emerging nano-scale communication systems. Traditionally, a detector recovers the information from only the concentration of single messenger molecule, while ignoring the variation of multiple participants in biochemical reaction. In this paper, we propose a non-coherent signal detector, by fully exploiting this ubiquitous biochemical diversity property of multiple reacting molecules. After extracting the channel state information (CSI) independent non-coherent features of received signals, the dynamical transient characteristics of messenger, reactant and product molecules are all utilized to implement the diversity detection, thus formulating a functional single-input multiple-output (SIMO) system via reaction-diffusion communication that has been barely considered before. We design both hard and soft combination strategies to attain the potential diversity gain arise from the dynamical co-variation of participants. Theoretical analysis and numerical simulations are provided to demonstrate the advantages of our detector. Compared with conventional detectors that use only single messenger molecule, the bit error rate (BER) of is substantially reduced. Moreover, the BER performances of our non-coherent detector are even better than coherent maximum a posteriori (MAP) detector that requires accurate CSI estimation, which confirms the dramatic diversity gain provided by our detector. It would have great potentials in reliable nano-scale communications.

In this paper, we propose a composite multiple-mode orthogonal frequency division multiplexing with index modulation (C-MM-OFDM-IM) scheme to increase the spectral efficiency (SE) of OFDM-IM systems by extending the indexing to the energy and constellation domains. In C-MM-OFDM-IM, the information bits are mapped to not only the subcarrier activation patterns (SAPs) and modulation symbols, but also the energy allocation patterns (EAPs) and constellation activation patterns (CAPs). To cope with the practical situations, we propose a variant IM scheme named C-MM-OFDM-IM-II to build a new mapping rule between information bits and the increased CAPs, capable of further increasing the SE of C-MM-OFDM-IM. Upper-bounded bit error rate (BER) and lower-bounded achievable rate are both derived in closed-form to evaluate the performance of C-MM-OFDM-IM(-II). Moreover, we further propose two enhanced schemes, named generalized C-MM-OFDM-IM(-II) and C-MM-OFDM with in-phase/quadrature IM(-II), where the former jointly considers all SAPs, EAPs, CAPs and modulated symbols, while the latter expands the index implementation to the in-phase and quadrature constellation domains. Simulation results show that C-MM-OFDM-IM(-II) outperforms the conventional OFDM-IM related schemes, especially in the high signal-to-noise ratio (SNR) region, and verify the accuracy of the theoretical analysis for the upper-bounded BER and achievable rate.

Overcoming inter-symbol interference (ISI) is one of the key challenges in the design of molecular communication systems. In this paper, we propose a scheme for optimizing the detection interval to minimize the impact of ISI while ensuring the acquisition of effective information. Our detection interval optimization applies to both the absorbing and passive receivers. For analysis, we consider as the performance metrics signal-to-interference difference (SID) and signal-to-interference and noise amplitude ratio (SINAR) proposed in the literature rather than the intractable bit error rate (BER). Accordingly, we derive the optimal detection interval in closedform. Finally, simulation results in terms of BER verify the theoretical analysis and also show the promising advantages of the proposed scheme in signal detection.

In this paper, we propose a two-layer heterogeneous network to realize the remote monitoring and advanced warning for infectious diseases spread by airborne pathogens, whose detection can be considered as a binary detection problem. To intuitively study the detection process, we abstract it as a molecular communication via diffusion (MCvD) model and uncover that one of the key factors to impact the detection performance is inter-symbol interference (ISI), i.e., the viral aerosol from other biological entities. Therefore, overcoming ISI is imperative to ensure reliable detection. In the abstracted MCvD model, the detection performance can be described by the bit error rate (BER) performance. Following this assumption, we propose to optimize the detection interval to minimize the impact of ISI while ensuring the accurate detection of the transmitted information symbol, which is suitable for both the absorbing and passive receivers. For tractability, based on the signal-to-interference difference (SID) and signal-to-interference-and-noise amplitude ratio (SINAR), we design a modified-SINAR (mSINAR) to measure BER performance for the MCvD system with a variable detection interval. Besides, we derive the optimal detection interval in closed-form. Using simulation results, we show that in terms of BER, our proposed mSINAR scheme is superior to the competitive schemes, and performs similarly to the scheme with optimal intervals determined by the exhaustive search.

Molecular communication (MC) is an emerging communication paradigm, where the information is carried via the patterns of molecules that are mainly governed by the diffusion process. Current MC literature concentrates on the time-domain analysis, while the signal analysis in other domains may facilitate the MC research. To this end, this paper performs the frequency-domain analysis by deriving the frequency response of the diffusion-based MC channels, manifesting an explicitly low-compass characteristic. The energy of the channel impulse response in the diffusion-based MC is also derived, and the corresponding bandwidth definition is proposed, which determines the sampling frequency for the one-shot diffusive channel impulse response in MC. The results in this work lay the foundation for the frequency-domain signal processing in diffusion-based MC channels.

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.

Molecular communication (MC) is a bio-inspired communication paradigm, which lays the foundation for the Internet of Bio-NanoThings (IoBNT) in the medical field. As a high energy-efficient information transfer method, MC via diffusion (MCvD) is envisioned as a promising candidate for IoBNT but suffers from low date rates due to the long tail of the channel impulse response (CIR). To this end, the multiple-input–multiple-output (MIMO) technique has been introduced to MCvD. However, the intersymbol interference (ISI) and interlink interference (ILI) deteriorate the bit error rate (BER) performance of MIMO MCvD systems. In this article, molecular type permutation shift keying in the space domain (MTPSK-SD) and time-interleaved MTPSK-SD are proposed for MIMO MCvD systems to improve the BER performance by reducing ILI. The principle of MTPSK-SD is further generalized to the spatiotemporal domain, yielding three spatiotemporal modulation schemes, which can provide desirable BER performance without requiring any CIR information in the communication scenarios affected by different levels of ISI and ILI. Two low-complexity detectors are proposed to obtain different tradeoffs between anti-ILI and anti-ISI performance. Furthermore, a complementary coding scheme, which can effectively reduce the ILI under the considered symmetrical system topology, is designed and applied to all the proposed modulation schemes. Additionally, the BER upper bound is analyzed. Numerical simulations on BER corroborate the analysis and show that the proposed schemes are promising multimolecule modulation alternatives, which outperform the existing MIMO MCvD modulation schemes.

In this paper, we present the space shift keying based molecular communication (SSK-MC), where the space symbol is of interest. For micro-scale SSK-MC, the information is embedded into the index of a single activated transmitter nanomachine, while the index of the sensor is considered for the macro-scale SSK-MC. The cancellation of the strongest inter-link interference in multiple-input multiple-output (MIMO) based MC is available with the implementation of SSK-MC, in which only one transmitter is activated during each symbol duration. We derive the symbol error rate (SER) of SSK-MC, which shows a perfect match with its numerical simulations. Apart from the theoretical analysis, we further design an underwater prototype under the 4×4 MIMO-MC configuration for SSK-MC, demonstrating its SER performance with different detection algorithms.

In this paper, a new channel model is presented for molecular communications (MC), where a point source emitted by the transmitter undergoes three phases, with effect of convection dominating in the first two phases, whereas diffusion prevailing in the final phase. The point source obtains its initial velocity and passes through the nozzle of the nanomachine transmitter in the first phase, followed by a deceleration process in the second phase. The free diffusion model is considered in the third phase. Based on this channel model, the energy transfer issue for two-way MC system is also taken into account, in which one of the transceivers is assumed to have abundant information molecules from its ambient environment, whereas the other one obtains the information molecules by implementing the simultaneous molecular information and energy transfer (SMIET). Finally, analytical bit error rate (BER) expressions are validated by computer simulations. Our results suggest that the symbol duration and the SMIET order significantly influence the BER performance in our two-way MC system.

In this paper, we study the performance of a downlink non-orthogonal multiple access-based cooperative relay system with a single relay over Nakagami-m fading channels, where both decode-and-forward (DF) and amplify-and-forward (AF) protocols are considered. We assume that only statistical channel state information is available to the system and used to determine the decoding order of cell-edge users' data. For DF relaying, both ergodic sum rate and outage probability are solved in closed form. For AF relaying, closed-form asymptotic ergodic sum rate and outage probability are provided. Numerical results verify the accuracy of the analysis and demonstrate that the DF protocol significantly outperforms the AF one in terms of ergodic sum rate even the channel's near-far effect weakens. In addition, the DF protocol exhibits better outage performance than the AF one at low signal-to-noise ratio (SNR), though the superiority becomes negligible with the increasing SNR.