The design and performance analysis of diffusive molecular communication systems

Molecular Communications (MC) is an increasingly attractive technique to enable the networking of nano-machines by utilising molecules as the information carrier. The molecular diffusion can be described by either the movement of individual molecules or the molecular concentration. Accordingly, two kinds of diffusive MC systems have been modelled in previous literature. On the basis of these studies, the aim of this Ph.D. is to refine these two models, to implement functional transmission techniques and technologies, and to investigate the corresponding system performance. To fulfil this target, the whole Ph.D. is divided into two stages. During each stage, specific tasks have been accomplished, each contributing to the overarching research field of diffusive MC systems. In the first stage, an MC system model, named as the Model-I, is established and enhanced by focusing on the motion of individual molecules. The performance has been evaluated by both deriving mathematical expressions and implementing MATLAB simulations. Based on the Model-I, a distance estimation scheme has been proposed. Compared with existing methods, this new scheme is more accurate and less time-consuming. Moreover, five Stop-and-Wait Automatic Repeat reQuest (SW-AQR) protocols have been implemented on the Model-I. Results reveal that all these SW-ARQ schemes work well and can be beneficial under different circumstances. In the second stage, another MC system model, named as the Model-II, is established and refined with information conveyed by the molecular concentration. Both theoretical derivations and MATLAB simulations are provided to analyse the system reliability. Laid on this foundation, two distance measurement methods have been proposed and shown to be suitable for the Model-II. Additionally, to solve the long-range MC problem, relaying schemes have been applied by deploying a relay node between the source and target nano-machines. The performance improvement of each scheme is also illustrated respectively

Simulating the performance of SW-ARQ schemes within molecular communications

This paper provides results on an investigation concerning the application of five tailored Stop-and-Wait Automatic Repeat reQuest (SW-ARQ) schemes to a diffusion based molecular communication system. Each scheme is numerically simulated and evaluated to determine its performance with regards to average time cost and energy consumption. It is shown that all five schemes are beneficial depending upon the application scenario. Scheme 1 is the best choice for adjacent communications although, if a slightly higher energy budget can be afforded, schemes 2 and 3 will provide better performance than scheme 1 as the communication distance increases. Schemes 4 and 5 are designed to benefit scenarios with either a varying channel or for a channel with unknown parameters although will also benefit a static channel if again, further system energy can be utilised. This optimisation and trade-off between time and energy requirement for a complete successful transmission will become more important in future applications involving molecular communications where energy efficiency is a design consideration

Distance estimation schemes for diffusion based molecular communication systems

Molecule concentration is often used as the information carrier to accomplish diffusion-based molecular communications (DMC) among nano-machines. To achieve the optimal functionality, knowing the distance between the transmitter nano-machine (TN) and the receiver nano-machine (RN) is of high importance. In this paper, two distance estimation schemes are proposed based upon the RN-sensed concentration which changes with regards to the time and distance. The RN estimates the distance by means of measuring either the concentration-peak time or received concentration energy. Simulations are performed to compare the accuracy of each scheme and to discover how the diffusion channel and noise may influence the accuracy. Results show that both schemes will provide a beneficial enhancement to molecular communication systems

Relay analysis in molecular communications with time-dependent concentration

Molecular communications (MC) is a promising paradigm which enables nano-machines to communicate with each other. Due to the severe attenuation of molecule concentrations, there tends to be more errors when the receiver becomes farther from the transmitter. To solve this problem, relaying schemes need to be implemented to achieve reliable communications. In this letter, time-dependent molecular concentrations are utilised as the information carrier, which will be influenced by the noise and channel memory. The emission process is also considered. The relay node (RN) can decode messages, and forward them by sending either the same or a different kind of molecules as the transmitter. The performance is evaluated by deriving theoretical expressions as well as through simulations. Results show that the relaying scheme will bring significant benefits to the communication reliability

An optimal decoding algorithm for molecular communications systems with noise, memory, and pulse width.

Molecular Communications (MC) is a promising paradigm to achieve message exchange between nano-machines. Due to the specific characteristics of MC systems, the channel noise and memory significantly influence the MC system performance. Aiming to mitigate the impact of these two factors, an adaptive decoding algorithm is proposed by optimising the symbol determination threshold. In this paper, this novel decoding scheme is deployed onto a concentration-based MC system with the transmitter emission process considered. To evaluate the performance, an information theoretical approach is developed to derive the Bit Error Rate (BER) and the channel capacity. Simulations are also carried out to verify the accuracy of these formulations, to compare the performance difference against other decoding schemes, and to illustrate the performance deviation caused by different designing of relevant parameters. Furthermore, the performance of MC systems with the distance unknown is also analysed. Comparisons between distance-pre-known and distance-unknown systems are provided

We are all in the same boat: The welfare and carbon abatement effects of the EU carbon border adjustment mechanism

Amid the escalating global climate crisis, the European Union (EU) has assumed a prominent role by introducing the Carbon Border Adjustment Mechanism (CBAM). This initiative aims to bolster climate action and mitigate carbon leakage. Nevertheless, considerable debate surrounds the practical efficacy of this measure and its conformity with World Trade Organization (WTO) regulations. This paper's objective is to quantitatively evaluate the welfare and carbon abatement effects of CBAM on the EU and other prominent economies. We develop a comprehensive multi-country, multi-sector general equilibrium model that incorporates EU carbon tariffs, global production networks, and carbon emissions to achieve this goal. The estimation of key parameters is conducted through a structural methodology that directly evaluates the impacts on welfare and carbon emissions resulting from unilateral or multilateral low-carbon policies. The analysis revealed that CBAM would enhance the welfare of the EU, Japan, South Korea, Norway, Switzerland, and the United States. Conversely, all other economies would experience a reduction in welfare, with Russia suffering the most significant loss and China the least. Furthermore, despite CBAM's effective global carbon emission reduction, its impact on the EU's domestic carbon reduction is limited. Counterfactual analyses indicate that global carbon emissions decrease in scenarios involving a globally standardized carbon pricing mechanism, China's elevation of carbon pricing alongside a carbon tariff, and the European Union's extension of taxation to all sectors. However, these scenarios result in substantial disparities in welfare levels among countries, with the most substantial reduction in global carbon emissions occurring exclusively with a globally harmonized carbon price, accompanied by the most minor overall welfare loss. In conclusion, this paper advocates for enhanced international collaboration and dialogue among nations to foster harmonizing carbon pricing policies and adopt a universally standardized carbon pricing mechanism

Energy requirements of error correction codes in diffusion-based molecular communication systems

Molecular Communications is a promising area with significant potential applications. To enhance the reliability of the transmission process, self-orthogonal convolutional codes (SOCCs) are proposed and investigated with respect to both bit error rate (BER) and energy efficiency. The codes are compared to both an un-coded system and one that employs Hamming codes to show that they can provide a benefit for molecular communication systems. The influence of the channel memory is also analysed in this paper. In addition, taking into account the extra energy required to implement the coding, the critical distance is investigated as another performance metric for nano-to-nano device communication, nano-to-macro device communication and macro-to-nano device communication. Considering the transmission distance and the operating BER of the designed system, the designer can determine whether the use of coding is beneficial or which code better suits the system

Cardiovascular toxicity profiles of immune checkpoint inhibitors with or without angiogenesis inhibitors: a real-world pharmacovigilance analysis based on the FAERS database from 2014 to 2022

BackgroundImmune checkpoint inhibitors (ICIs) combined with angiogenesis inhibitors (AGIs) have become increasingly available for multiple types of cancers, although the cardiovascular safety profiles of this combination therapy in real-world settings have not been elucidated to date. Therefore, we aimed to comprehensively investigate the cardiovascular toxicity profiles of ICIs combined with AGIs in comparison with ICIs alone.MethodsThe Food and Drug Administration Adverse Event Reporting System (FAERS) database from the 1st quarter of 2014 to the 1st quarter of 2022 was retrospectively queried to extract reports of cardiovascular adverse events (AEs) associated with ICIs alone, AGIs alone and combination therapy. To perform disproportionality analysis, the reporting odds ratios (RORs) and information components (ICs) were calculated with statistical shrinkage transformation formulas and a lower limit of the 95% confidence interval (CI) for ROR (ROR025) > 1 or IC (IC025) > 0 with at least 3 reports was considered statistically significant.ResultsA total of 18 854 cardiovascular AE cases/26 059 reports for ICIs alone, 47 168 cases/67 595 reports for AGIs alone, and 3 978 cases/5 263 reports for combination therapy were extracted. Compared to the entire database of patients without AGIs or ICIs, cardiovascular AEs were overreported in patients with combination therapy (IC025/ROR025 = 0.559/1.478), showing stronger signal strength than those taking ICIs alone (IC025/ROR025 = 0.118/1.086) or AGIs alone (IC025/ROR025 = 0.323/1.252). Importantly, compared with ICIs alone, combination therapy showed a decrease in signal strength for noninfectious myocarditis/pericarditis (IC025/ROR025 = 1.142/2.216 vs. IC025/ROR025 = 0.673/1.614), while an increase in signal value for embolic and thrombotic events (IC025/ROR025 = 0.147/1.111 vs. IC025/ROR025 = 0.591/1.519). For outcomes of cardiovascular AEs, the frequency of death and life-threatening AEs was lower for combination therapy than ICIs alone in noninfectious myocarditis/pericarditis (37.7% vs. 49.2%) as well as in embolic and thrombotic events (29.9% vs. 39.6%). Analysis among indications of cancer showed similar findings.ConclusionOverall, ICIs combined with AGIs showed a greater risk of cardiovascular AEs than ICIs alone, mainly due to an increase in embolic and thrombotic events while a decrease in noninfectious myocarditis/pericarditis. In addition, compared with ICIs alone, combination therapy presented a lower frequency of death and life-threatening in noninfectious myocarditis/pericarditis and embolic and thrombotic events