Molecular dynamics simulations to develop novel solvents for deep desulfurization of diesel

For the last decade, deep eutectic solvent (DES), a novel solvent, has gathered lots of attention due to their favorable properties such as a low melting point, non-toxicity and low-cost. In this work, a combination of tetrabutylammonium chloride (TBAC), polyethylene glycol (PEG-200), and ferric chloride (FeCl3) at a molar ratio of 4:1:0.05, a metallic based deep eutectic solvent is analyzed using molecular dynamics simulation. The analysis reveals the interactions between the components of DES, which might lead to the formation of the DES, i.e., strong depression in the melting point as compared to the individual component. Further, the solvent was also tested for fuel desulfurization using molecular simulations. For the analysis n-octane was chosen as fuel with ~2000 ppm dibenzothiophene and the results suggest strong absorption of sulfur compounds by the DES. Molecular dynamics simulations were performed using GROMACS to explore different interactions occurring between the components of the DESs and model oil at a molecular level. Interaction energies between compounds and radial distribution functions indicate a strong interaction between the tetrabutylammonium ion with the dibenzothiophene molecule. The given work also shows that the DES can be applied for diesel even with high initial concentration of sulfur content and can be applicable for extraction of different sulfur compounds such as benzothiophene (BT) and thiophene (TS). Additionally, among all tested temperature ranges it was found that use of the room temperature is beneficial for the desulfurization process. Moreover, composition of DES was varied by selectively removing either PEG or FeCl3 from the DES to evaluate the influence of each compound on the efficiency of desulfurization process

THROUGHPUT OPTIMIZATION AND ENERGY EFFICIENCY OF THE DOWNLINK IN THE LTE SYSTEM

Nowadays, the usage of smart phones is very popular. More and more people access the Internet with their smart phones. This demands higher data rates from the mobile network operators. Every year the number of users and the amount of information is increasing dramatically. The wireless technology should ensure high data rates to be able to compete with the wire-based technology. The main advantage of the wireless system is the ability for user to be mobile. The 4G LTE system made it possible to gain very high peak data rates. The purpose of this thesis was to investigate the improvement of the system performance for the downlink based on different antenna configurations and different scheduling algorithms. Moreover, the fairness between the users using different schedulers has been analyzed and evaluated. Furthermore, the energy efficiency of the scheduling algorithms in the downlink of LTE systems has been considered. Some important parts of the LTE system are described in the theoretical part of this thesis.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format

System-Level Analysis of Blockage Dynamics in Millimeter-Wave Communications

The new generation of wireless technology, termed as the fifth generation (5G), introduces a large amount of novel features. An operation in the millimeter-wave (mmWave) spectrum becomes one of those features unlocking a wide bandwidth. The latter allows for a notable increase in the peak data rate by up to tens of gigabits per second and decreases latency to as low as few milliseconds. These improvements provide an opportunity to support high-rate and low-latency applications, such as augmented and virtual reality, eHealth, and many others. Though mmWave communications have great potential, they suffer from severe attenuation caused by signal blockage. In addition to large-scale blockers (i.e., buildings), small-scale blockers such as human bodies bring new challenges to the operation over mmWave bands. Large attenuation losses, as well as the unpredictable mobility of human body blockers, can significantly decrease a service quality when communicating over a mmWave link. Thereby, there is a need to properly model the blockage process, evaluate its impact on mmWave network performance, and estimate performance gains brought by different blockage mitigation techniques. The thesis proposes a mathematical methodology to characterize and evaluate the effect of blockage dynamics in mmWave networks. With the help of stochastic geometry and probability theory, it delivers mathematical models of static and dynamic small-scale blockage, as well as static large-scale blockage. It then introduces system-level performance evaluation frameworks accounting for the main features of mmWave communications, such as blockage and multipath propagation. The mathematical frameworks can also evaluate the impact of several blockage mitigation techniques in realistic deployment scenarios

An Accurate Approximation of Resource Request Distributions in Millimeter Wave 3GPP New Radio Systems

The recently standardized millimeter wave-based 3GPP New Radio technology is expected to become an enabler for both enhanced Mobile Broadband (eMBB) and ultra-reliable low latency communication (URLLC) services specified to future 5G systems. One of the first steps in mathematical modeling of such systems is the characterization of the session resource request probability mass function (pmf) as a function of the channel conditions, cell size, application demands, user location and system parameters including modulation and coding schemes employed at the air interface. Unfortunately, this pmf cannot be expressed via elementary functions. In this paper, we develop an accurate approximation of the sought pmf. First, we show that Normal distribution provides a fairly accurate approximation to the cumulative distribution function (CDF) of the signal-to-noise ratio for communication systems operating in the millimeter frequency band, further allowing evaluating the resource request pmf via error function. We also investigate the impact of shadow fading on the resource request pmf.Comment: The 19th International Conference on Next Generation Wired/Wireless Networks and Systems (New2An 2019

On the Temporal Effects of Mobile Blockers in Urban Millimeter-Wave Cellular Scenarios

Millimeter-wave (mmWave) propagation is known to be severely affected by the blockage of the line-of-sight (LoS) path. In contrast to microwave systems, at shorter mmWave wavelengths such blockage can be caused by human bodies, where their mobility within environment makes wireless channel alternate between the blocked and non-blocked LoS states. Following the recent 3GPP requirements on modeling the dynamic blockage as well as the temporal consistency of the channel at mmWave frequencies, in this paper a new model for predicting the state of a user in the presence of mobile blockers for representative 3GPP scenarios is developed: urban micro cell (UMi) street canyon and park/stadium/square. It is demonstrated that the blockage effects produce an alternating renewal process with exponentially distributed non-blocked intervals, and blocked durations that follow the general distribution. The following metrics are derived (i) the mean and the fraction of time spent in blocked/non-blocked state, (ii) the residual blocked/non-blocked time, and (iii) the time-dependent conditional probability of having blockage/no blockage at time t1 given that there was blockage/no blockage at time t0. The latter is a function of the arrival rate (intensity), width, and height of moving blockers, distance to the mmWave access point (AP), as well as the heights of the AP and the user device. The proposed model can be used for system-level characterization of mmWave cellular communication systems. For example, the optimal height and the maximum coverage radius of the mmWave APs are derived, while satisfying the required mean data rate constraint. The system-level simulations corroborate that the use of the proposed method considerably reduces the modeling complexity.Comment: Accepted, IEEE Transactions on Vehicular Technolog

Standardization of Extended Reality (XR) over 5G and 5G-Advanced 3GPP New Radio

Extended Reality (XR) is one of the major innovations to be introduced in 5G/5G-Advanced communication systems. A combination of augmented reality, virtual reality, and mixed reality, supplemented by cloud gaming, revisits the way how humans interact with computers, networks, and each other. However, efficient support of XR services imposes new challenges for existing and future wireless networks. This article presents a tutorial on integrating support for the XR into the 3GPP New Radio (NR), summarizing a range of activities handled within various 3GPP Service and Systems Aspects (SA) and Radio Access Networks (RAN) groups. The article also delivers a case study evaluating the performance of different XR services in state-of-the-art NR Release 17. The paper concludes with a vision of further enhancements to better support XR in future NR releases and outlines open problems in this area.Comment: 7 pages, 4 figures, 2 tables. This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessibl

Hover or Perch: Comparing Capacity of Airborne and Landed Millimeter-Wave UAV Cells

On-demand deployments of millimeter-wave (mmWave) access points (APs) carried by unmanned aerial vehicles (UAVs) are considered today as a potential solution to enhance the performance of 5G+ networks. The battery lifetime of modern UAVs, though, limits the flight times in such systems. In this letter, we evaluate a feasible deployment alternative for temporary capacity boost in the areas with highly fluctuating user demands. The approach is to land UAV-based mmWave APs on the nearby buildings instead of hovering over the area. Within the developed mathematical framework, we compare the system-level performance of airborne and landed deployments by taking into account the full operation cycle of the employed drones. Our numerical results demonstrate that the choice of the UAV deployment option is determined by an interplay of the separation distance between the service area and the UAV charging station, drone battery lifetime, and the number of aerial APs in use. The presented methodology and results can support efficient on-demand deployments of UAV-based mmWave APs in prospective 5G+ networks.Comment: Accepted to IEEE Wireless Communications Letters on July 20, 2020. Copyright may be transferred without further notice after which this version may become non-availabl

Aerial Access and Backhaul in mmWave B5G Systems: Performance Dynamics and Optimization

The use of unmanned aerial vehicle (UAV)-based communication in millimeter-wave (mmWave) frequencies to provide on-demand radio access is a promising approach to improve capacity and coverage in beyond-5G (B5G) systems. There are several design aspects to be addressed when optimizing for the deployment of such UAV base stations. As traffic demand of mobile users varies across time and space, dynamic algorithms that correspondingly adjust the UAV locations are essential to maximize performance. In addition to careful tracking of spatio-temporal user/traffic activity, such optimization needs to account for realistic backhaul constraints. In this work, we first review the latest 3GPP activities behind integrated access and backhaul system design, support for UAV base stations, and mmWave radio relaying functionality. We then compare static and mobile UAV-based communication options under practical assumptions on the mmWave system layout, mobility and clusterization of users, antenna array geometry, and dynamic backhauling. We demonstrate that leveraging the UAV mobility to serve moving users may improve the overall system performance even in the presence of backhaul capacity limitations.Comment: 7 pages, 5 figures. This work has been accepted to IEEE Communications Magazine, 201

Molecular dynamics simulations to develop novel solvents for deep desulfurization of diesel

For the last decade, deep eutectic solvent (DES), a novel solvent, has gathered lots of attention due to their favorable properties such as a low melting point, non-toxicity and low-cost. In this work, a combination of tetrabutylammonium chloride (TBAC), polyethylene glycol (PEG-200), and ferric chloride (FeCl3) at a molar ratio of 4:1:0.05, a metallic based deep eutectic solvent is analyzed using molecular dynamics simulation. The analysis reveals the interactions between the components of DES, which might lead to the formation of the DES, i.e., strong depression in the melting point as compared to the individual component. Further, the solvent was also tested for fuel desulfurization using molecular simulations. For the analysis n-octane was chosen as fuel with ~2000 ppm dibenzothiophene and the results suggest strong absorption of sulfur compounds by the DES. Molecular dynamics simulations were performed using GROMACS to explore different interactions occurring between the components of the DESs and model oil at a molecular level. Interaction energies between compounds and radial distribution functions indicate a strong interaction between the tetrabutylammonium ion with the dibenzothiophene molecule. The given work also shows that the DES can be applied for diesel even with high initial concentration of sulfur content and can be applicable for extraction of different sulfur compounds such as benzothiophene (BT) and thiophene (TS). Additionally, among all tested temperature ranges it was found that use of the room temperature is beneficial for the desulfurization process. Moreover, composition of DES was varied by selectively removing either PEG or FeCl3 from the DES to evaluate the influence of each compound on the efficiency of desulfurization process