Spectral-energy efficiency trade-off for next-generation wireless communication systems

The data traffic in cellular networks has had and will experience a rapid exponential rise. Therefore, it is essential to innovate a new cellular architecture with advanced wireless technologies that can offer more capacity and enhanced spectral efficiency to manage the exponential data traffic growth. Managing such mass data traffic, however, brings up another challenge of increasing energy consumption. This is because it contributes into a growing fraction of the carbon dioxide (CO2) emission which is a global concern today due to its negative impact on the environment. This has resulted in creating a new paradigm shift towards both spectral and energy efficient orientated design for the next-generation wireless access networks. Acquiring both improved energy efficiency and spectral efficiency has, nonetheless, shown to be a difficult goal to achieve as it seems improving one is at the detriment to the other. Therefore, the trade-off between the spectral and energy efficiency is of paramount importance to assess the energy consumption in a wireless communication system required to attain a specific spectral efficiency. This thesis looks into this problem. It studies the spectral-energy efficiency tradeoff for some of the emerging wireless communication technologies which are seen as potential candidates for the fifth generation (5G) mobile cellular system. The focus is on the orthogonal frequency division multiple access (OFDMA), mobile femtocell (MFemtocell), cognitive radio (CR), and the spatial modulation (SM). Firstly, the energy-efficient resource allocation scheme for multi-user OFDMA (MU-OFDMA) system is studied. The spectral-energy efficiency trade-off is analysed under the constraint of maintaining the fairness among users. The energy-efficient optimisation problem has been formulated as integer fractional programming. We then apply an iterative method to simplify the problem to an integer linear programming (ILP) problem. Secondly, the spectral and energy efficiency for a cellular system with MFemtocell deployment is investigated using different resource partitioning schemes. Femtocells are low range, low power base stations (BSs) that improve the coverage inside a home or office building. MFemtocell adopts the femtocell solution to be deployed in public transport and emergency vehicles. Closed-form expressions for the relationships between the spectral and energy efficiency are derived for a single-user (SU) MFemtocell network. We also study the spectral efficiency for MU-MFemtocells with two opportunistic scheduling schemes. Thirdly, the spectral-energy efficiency trade-off for CR networks is analysed at both SU and MU CR systems against varying signal-to-noise ratio (SNR) values. CR is an innovative radio device that aims to utilise the spectrum more efficiently by opportunistically exploiting underutilised licensed spectrum. For the SU system, we study the required energy to achieve a specific spectral efficiency for a CR channel under two different types of power constraints in different fading environments. In this scenario, interference constraint at the primary receiver (PR) is also considered to protect the PR from harmful interference. At the system level, we study the spectral and energy efficiency for a CR network that shares the spectrum with an indoor network. Adopting the extreme-value theory, we are able to derive the average spectral efficiency of the CR network. Finally, we propose two innovative schemes to enhance the capability of (SM). SM is a recently developed technique that is employed for a low complexity multipleinput multiple-output (MIMO) transmission. The first scheme can be applied for SU MIMO (SU-MIMO) to offer more degrees of freedom than SM. Whereas the second scheme introduces a transmission structure by which the SM is adopted into a downlink MU-MIMO system. Unlike SM, both proposed schemes do not involve any restriction into the number of transmit antennas when transmitting signals. The spectral-energy efficiency trade-off for the MU-SM in the massive MIMO system is studied. In this context, we develop an iterative energy-efficient water-filling algorithm to optimises the transmit power and achieve the maximum energy efficiency for a given spectral efficiency. In summary, the research presented in this thesis reveals mathematical tools to analysis the spectral and energy efficiency for wireless communications technologies. It also offers insight to solve optimisation problems that belong to a class of problems with objectives of enhancing the energy efficiency

Waveband Luminosity Correlations in Flux-Limited Multiwavelength Data

We explore the general question of correlations among different waveband luminosities in a flux-limited multiband observational data set. Such correlations, often observed for astronomical sources, may be either intrinsic or induced by the redshift evolution of the luminosities and the data truncation due to the flux limits. We first address this question analytically. We then use simulated flux-limited data with three different known intrinsic luminosity correlations and prescribed luminosity functions and evolution similar to the ones expected for quasars. We explore how the intrinsic nature of luminosity correlations can be deduced, including exploring the efficacy of partial correlation analysis with redshift binning in determining whether luminosity correlations are intrinsic and finding the form of the intrinsic correlation. By applying methods that we have developed in recent works, we show that we can recover the true cosmological evolution of the luminosity functions and the intrinsic correlations between the luminosities. Finally, we demonstrate the methods for determining intrinsic luminosity correlations on actual observed samples of quasars with mid-infrared, radio, and optical fluxes and redshifts, finding that the luminosity-luminosity correlation is significantly stronger between mid-infrared and optical than that between radio and optical luminosities, supporting the canonical jet-launching and heating model of active galaxies

Measuring Water Poverty Index in Urban Areas of Punjab

The urban population of Punjab is growing rapidly. It is projected that there will be a 25 to 30 percent increase in urban population by 2020. This rapid population increase is causing major problems in the efficient provision of urban services in these cities. To evaluate the effect of this population increase, this paper tries to produce an integrated assessment of water stress and scarcity, linking physical estimates of water availability with socioeconomic variables that reflect poverty, i.e., a Water Poverty Index. It is understood that poor households face the problem of the accessibility of potable water, and this results in a significant loss of time and effort, especially for women. On the basis of multiple data sources, this paper evaluates water poverty in three panels of large, intermediate, and small cities of Punjab. The results show the same water poverty level within the panels but a higher poverty level in large cities than small and intermediate cities

Stringent Internal Quality Control Procedures in Chemical Pathology Lead to Better Performance in External Proficiency Testing

Objective: To assess impact of stringent Internal Quality Control (IQC) checks on performance of proficiency testing Material and methods: This was a Prospective study conducted between September 2020 and April 2021 at Chemical pathology lab of Fauji Foundation Hospital Rawalpindi. External quality control data (EQC) from the month of September was evaluated. As part of corrective action plan IQC checks were enforced, internal quality control (IQC) data of the month of September 2020 and April 2022 were assessed. Performance characteristics of routine chemistry analytes coefficient of variance (CV), standard deviations (SD)and Bias were calculated and compared using paired –T- test. Results:  Proficiency testing report (NEQAPP) of cycle 10 round 1 showed 11% External Quality Control (EQC) failure among 18 biochemical parameters. Serum Creatinine and Total Protein failed acceptability criteria with Z-score of greater than 2. As part of corrective action IQC checks were done, which led to improvement in CV (SD) of these parameters. The next EQC lab report for routine chemistry analytes met the acceptability criteria with z-scores of all anaytes being less than 2. Conclusion: Precise & accurate IQC results lead to better performance in EQC result

Optimization of secure wireless communications for IoT networks in the presence of eavesdroppers

The problem motivates this paper is that securing the critical data of 5G based wireless IoT network is of significant importance. Wireless 5G IoT systems consist of a large number of devices (low-cost legitimate users), which are of low complexity and under strict energy constraints. Physical layer security (PLS) schemes, along with energy harvesting, have emerged as a potential candidate that provides an effective solution to address this issue. During the data collection process of IoT, PHY security techniques can exploit the characteristics of the wireless channel to ensure secure communication. This paper focuses on optimizing the secrecy rate for simultaneous wireless information and power transfer (SWIPT) IoT system, considering that the malicious eavesdroppers can intercept the data. In particular, the main aim is to optimize the secrecy rate of the system under signal to interference noise ratio (SINR), energy harvesting (EH), and total transmits power constraints. We model our design as an optimization problem that advocates the use of additional noise to ensure secure communication and guarantees efficient wireless energy transfer. The primary problem is non-convex due to complex objective functions in terms of transmit beamforming matrix and power splitting ratios. We have considered both the perfect channel state information (CSI) and the imperfect CSI scenarios. To circumvent the non-convexity of the primary problem in perfect CSI case, we proposed a solution based on the concave-convex procedure (CCCP) iterative algorithm, which results in a maximum local solution for the secrecy rate. In the imperfect CSI scenario, we facilitate the use of S-procedure and present a solution based on the iterative successive convex approximation (SCA) approach. Simulation results present the validations of the proposed algorithms. The results provide an insightful view that the proposed iterative method based on the CCCP algorithm achieves higher secrecy rates and lower computational complexity in comparison to the other algorithms

Evaluation of the relation between the maxillary sinus and the posterior teeth using digital panoramic radiography

This research aimed to determine the relationship between the maxillary posterior teeth and maxillary sinus floor (MSF), as well as the impact of nearby tooth loss on the space between MSF and posterior maxillary roots. A number of 120 digital panoramic radiographs were obtained from the archives of several clinics in Al-Najaf, Iraq, with the overall teeth examined in these radiographs including 236 of the 1st premolars, 227 of the 2nd premolars, 227 of the 1st molars, and 231 of the 2nd molars, from the right and left sides. The distances between the apices of the teeth and the maxillary sinus were determined. There are three categories of relationships between upper posterior teeth roots and MSF. These include type Os (root apex exists below or outside MSF), Type Co (root apex in contact with the MSF), and Type Is (root apex above or inside MSF). Type Os is the most encountered among premolars, Type Co is mostly encountered among the 2nd molars, and Type Is, in the 1st and 2nd molars. The study finds no correlation between age, gender, and the distribution of maxillary posterior tooth roots attached to the MSF. The first premolars were the furthest from MS, while the first molars were the closest. The most frequent link between maxillary molar roots and the MS was the Co-relation for the 2nd maxillary molar and the Is relation for the 1st maxillary molar. There is a non-significant decrease in the distance between the apices of the 1st maxillary premolar, 2nd maxillary premolar, and 1st maxillary molar and the MS before and after extraction

Characterization of Environmental Dust in the Dammam Area and Mud After-Effects on Bisphenol-A Polycarbonate Sheets

Owing to recent climate changes, dust storms are increasingly common, particularly in the Middle East region. Dust accumulation and subsequent mud formation on solid surfaces in humid environments typically have adverse effects on surface properties such as optical transmittance, surface texture, and microhardness. This is usually because the mud, which contains alkaline and ionic species, adheres strongly to the surface, often through chemical bonds, and is therefore difficult to remove. In this study, environmental dust and the after-effects of mud formed on a polycarbonate sheet, which is commonly used as a protective glass in photovoltaic cells. Ionic compounds (OH−) are shown to significantly affect the optical, mechanical, and textural characteristics of the polycarbonate surface, and to increase the adhesion work required to remove the dry mud from the polycarbonate surface upon drying. Such ability to modify characteristics of the polycarbonate surface could address the dust/mud-related limitations of superhydrophobic surfaces

Protection of a smart grid with the detection of cyber- malware attacks using efficient and novel machine learning models

False data injection (FDI) attacks commonly target smart grids. Using the tools that are now available for detecting incorrect data, it is not possible to identify FDI attacks. One way that can be used to identify FDI attacks is machine learning. The purpose of this study is to analyse each of the six supervised learning (SVM-FS) hybrid techniques using the six different boosting and feature selection (FS) methodologies. A dataset from the smart grid is utilised in the process of determining the applicability of various technologies. Comparisons of detection strategies are made based on how accurately each one can identify different kinds of threats. The performance of classification algorithms that are used to detect FDI assaults is improved by the application of supervised learning and hybrid methods in a simulated exercise

Li-Pos: A Light Positioning Framework Leveraging OFDM for Visible Light Communication

The design of solid-state lighting is vital, as numerous metrics are involved in their exact positioning, and as it is utilized in various processes, ranging from intelligent buildings to the internet of things (IoT). This work aims to determine the power and delay spread from the light source to the receiver plane. The positions of the light source and receiver were used for power estimation. We focus on analog orthogonal frequency-division multiplexing (OFDM) in visible light communication (VLC) and assess the area under the curve (AUC). The proposed system was designed using modulation techniques (i.e., quadrature amplitude modulation; QAM) for visible light communication (VLC) and pulse-width modulation (PWM) for dimming sources. For the positioning and spreading of brightness, the proof-of-concept was weighted equally over the entire area. Therefore, the receiver plane was analyzed, in order to measure the power of each light-emitting diode (LED) in a given area, using the delayed mean square error (MSE). A framework was applied for the placement of LEDs, using full-width at half-maximum (FWHM) parameters with varying distances. Then, the received power was confirmed. The results show that the AUC using DRMS values for LEDs significantly increased (by 30%) when the number of source LEDs was changed from four to three. These results confirm that our system, associated with the simple linear lateration estimator, can achieve better energy consumption