Dimming control in visible light communication using RPO-OFDM and concatenated RS-CC

Increasing wireless data traffic is creating pressure on the conventional dwindling radio frequency spectrum. A new and reliable communication medium becomes a necessity. Visible Light Communication (VLC), a subset of optical wireless communication uses the visible light spectrum between 400 and 800 THz as a medium for communication. VLC utilizes the illumination of LED to establish a communication medium. The research focused on achieving a successful VLC communication link at low intensities of light without affecting the speed, accuracy and efficiency of VLC. The achievement of the paper was to devise a method to reduce the LED brightness, reducing energy consumption and most importantly maintain a reliable, efficient and successful VLC communication link at low intensities of LED. The research comprises of a Reverse Polarity Optical-Orthogonal Frequency Division Multiplexing (RPO-OFDM) modulator, a Forward Error Correction (FEC) encoder block that uses concatenated Reed Solomon - Convolutional Coding, a digital PWM dimming control circuit, an RPO-OFDM demodulator and a FEC decoder. The decoding is performed using the Berlekamp-Massey algorithm and the Viterbi algorithm. Extensive research on various modulation schemes, coding and error correction techniques along with various driver circuit design for dimming control in VLC were thoroughly investigated to conclude the best reliable solution for dimming control in VLC

Slope line coding for telecommunication networks

A new slope line code for information transmission and storage has been proposed. The line code operates on the principle of slope coding. Two alternative slopes are used to transmit or store the binary information 1 s and 0 s. The decoder extracts the binary information from the received multilevel signal using slope comparison technique with slope violation detector from the incoming symbols. The encoder and decoder operation is described. A simulation of the encoder and decoder has been carried out using MultiSIM® software. The simulated results are in thorough agreement with the theory. The slope line code also meets the many desirable features of other line codes. This makes it attractive and suitable for data transmission and storage on different types of telecommunication networks and multimedia systems

Global, regional, and national disability-adjusted life-years (DALYs) for 333 diseases and injuries and healthy life expectancy (HALE) for 195 countries and territories, 1990–2016: a systematic analysis for the Global Burden of Disease Study 2016

BACKGROUND: Measurement of changes in health across locations is useful to compare and contrast changing epidemiological patterns against health system performance and identify specific needs for resource allocation in research, policy development, and programme decision making. Using the Global Burden of Diseases, Injuries, and Risk Factors Study 2016, we drew from two widely used summary measures to monitor such changes in population health: disability-adjusted life-years (DALYs) and healthy life expectancy (HALE). We used these measures to track trends and benchmark progress compared with expected trends on the basis of the Socio-demographic Index (SDI). METHODS: We used results from the Global Burden of Diseases, Injuries, and Risk Factors Study 2016 for all-cause mortality, cause-specific mortality, and non-fatal disease burden to derive HALE and DALYs by sex for 195 countries and territories from 1990 to 2016. We calculated DALYs by summing years of life lost and years of life lived with disability for each location, age group, sex, and year. We estimated HALE using age-specific death rates and years of life lived with disability per capita. We explored how DALYs and HALE differed from expected trends when compared with the SDI: the geometric mean of income per person, educational attainment in the population older than age 15 years, and total fertility rate. FINDINGS: The highest globally observed HALE at birth for both women and men was in Singapore, at 75·2 years (95% uncertainty interval 71·9-78·6) for females and 72·0 years (68·8-75·1) for males. The lowest for females was in the Central African Republic (45·6 years [42·0-49·5]) and for males was in Lesotho (41·5 years [39·0-44·0]). From 1990 to 2016, global HALE increased by an average of 6·24 years (5·97-6·48) for both sexes combined. Global HALE increased by 6·04 years (5·74-6·27) for males and 6·49 years (6·08-6·77) for females, whereas HALE at age 65 years increased by 1·78 years (1·61-1·93) for males and 1·96 years (1·69-2·13) for females. Total global DALYs remained largely unchanged from 1990 to 2016 (-2·3% [-5·9 to 0·9]), with decreases in communicable, maternal, neonatal, and nutritional (CMNN) disease DALYs offset by increased DALYs due to non-communicable diseases (NCDs). The exemplars, calculated as the five lowest ratios of observed to expected age-standardised DALY rates in 2016, were Nicaragua, Costa Rica, the Maldives, Peru, and Israel. The leading three causes of DALYs globally were ischaemic heart disease, cerebrovascular disease, and lower respiratory infections, comprising 16·1% of all DALYs. Total DALYs and age-standardised DALY rates due to most CMNN causes decreased from 1990 to 2016. Conversely, the total DALY burden rose for most NCDs; however, age-standardised DALY rates due to NCDs declined globally. INTERPRETATION: At a global level, DALYs and HALE continue to show improvements. At the same time, we observe that many populations are facing growing functional health loss. Rising SDI was associated with increases in cumulative years of life lived with disability and decreases in CMNN DALYs offset by increased NCD DALYs. Relative compression of morbidity highlights the importance of continued health interventions, which has changed in most locations in pace with the gross domestic product per person, education, and family planning. The analysis of DALYs and HALE and their relationship to SDI represents a robust framework with which to benchmark location-specific health performance. Country-specific drivers of disease burden, particularly for causes with higher-than-expected DALYs, should inform health policies, health system improvement initiatives, targeted prevention efforts, and development assistance for health, including financial and research investments for all countries, regardless of their level of sociodemographic development. The presence of countries that substantially outperform others suggests the need for increased scrutiny for proven examples of best practices, which can help to extend gains, whereas the presence of underperforming countries suggests the need for devotion of extra attention to health systems that need more robust support. FUNDING: Bill & Melinda Gates Foundation

Energy efficiency of visible light communication using SEE-OFDM

Wireless internet access technology can experience a major revolution through the use of breakthrough technology of Visible Light Communication (VLC) or Li-Fi (light fidelity) which could promise much higher data rates and better security and integrity of the data at the physical layer. There are many challenges being faced when visible light communication is being used resulting in low efficiency of the system. The main purpose of this paper is to endeavour to achieve highest data rate possible in an indoor environment while tackling problems which include loss of energy efficiency as OFDM is made unipolar and real-valued.A novel unipolar scheme called \u27Spectral and Energy efficient\u27 (SEE-OFDM) is proposed which is compatible with IM/DD wireless systems and is a great candidate for VLC. SEE-OFDM delivered promising results as it doubles the spectral efficiency of unipolar OFDM format. The fundamental idea is to generate multiple signals and sum them; both even and odd subcarriers are transmitted to carry information and the signal remains immune to interference. It is an attractive choice since higher data rates and SNR are gained, with a significant reduction in PAPR relative to conventional ACO-OFDM

Integrated broadband powerline and visible light communication (VLC) using OFDM and turbo coding

This paper is focused on the communication scheme and its integration of Power Line Communication (PLC) and Visible Light Communication (VLC) systems. As the power line communication is becoming more popular in the last mile and home networking. In order to make the Power Line Communication (PLC) based networks more practical by having mobility at the last inch connectivity the VLC can be utilised. Some work has been done in the area of using power line for communications but these systems suffer from noise, inter symbol interference (ISI), and distortion. Most of the current proposed integrated systems are through Direct Sequence Spread Spectrum (DSSS) and OFDM techniques, where they are considered as candidates for future broadband PLC networks. Our work is different in a sense that it is incorporating turbo codes in the integrated system to increase the system robustness to noise, ISI and distortion. The signal data to be transmitted will be connected through the Power Line modulator which is connected to the wall socket. The PLC modulator is then connected to the VLC modulator for the transmission of the signal in the air. At the receiver side however, the transmitted signal is then received through the VLC demodulator followed by the PLC demodulator. By introducing the turbo coder and decoder we were able to achieve a better performance for the integrated system to noise, ISI, and distortion. The performance of the system was measured through comparing the BER rate for the system with and without the turbo codes. The BER rate was also measured with respect to the signal to noise ratio, and data rate. Simulation results using Matlab was conducted to show the systems performance towards noise and other factors. A practical implementation for the PLC was assembled to better support the simulation results

Optimal pilot matrix design for training-based channel estimation in MIMO communications

This paper considers pilot-based (or training-based) channel matrix estimation in downlink multiuser multiple input multiple output (MIMO) wireless communication systems under Rician fading. The Bayesian approach is used to analyse and derive closed-form mathematical expressions for the minimum mean square estimator (MMSE) and the mean square error (MSE) in estimating the channel state information (CSI) where the long-term channel statistics are known a priori. It is shown how the pilot matrix can be designed to maximize the estimation performance. MATLAB simulation examples are used to evaluate the performance of the MMSE channel estimator for different training sequences and system statistics and to show how both the optimal length of the training sequence (number of columns of the pilot matrix) and the channel estimation error decreases with the spatial correlatio

The slope line code for digital communication systems

A novel slope line code for data transmission and storage on digital communication systems has been proposed. The new line code operates on the principle of slope coding. The slope encoder transmits alternative slopes (stair-step-like pulses) for the transmission of the 1s and 0s of the input binary data. The decoder detects the received signal using correlative slope technique in order to extract the transmitted binary 1s and 0s from the incoming symbols. The encoder and decoder operation were described. The encoder circuit is designed and simulated using MultiSim software. The results show a thorough match with the theory. The new line code has many desirable properties which makes it attractive and a suitable for data transmission and storage on different types of telecommunication networks and multimedia

The H-ternary line code power spectral density modelling investigation

The power spectral density of the H-ternary line code is investigated in this paper. Accurate simulation results are extracted from a simulation model that generates and encodes very long P-N binary sequence. The simulation results are compared with that of the theoretical results obtained from the analytical model. Both results almost fit with each other except for very low frequency components where the simulation results drift slightly. This deviation is a result of the fact that the simulation model is able to generate more realistic data sequence that mimics real-world data

Implementing vertical and horizontal engineering students\u27 integration and assessment of consequence academic achievement

Recent scholarship references indicate that integration of the student body can result in an enhanced learning experience for students and also greater satisfaction. This paper reports the results of a case study whereby mechanical engineering students studying at a newly established branch campus in Dubai of a British university were exposed to vertical and horizontal integration. Different activities have been embedded to ensure that students integrated and worked together with their peers and colleagues at different levels. The implemented processes and practices led to improved academic achievements, which were better than those of a similar cohort of students where no effort had been made to integrate. The analysis revealed that cooperative learning and the degree of academic support provided by teachers are positively and directly correlated with academic as well as the students’ own sense of personal achievement. The results are discussed in light of previous research and with reference to the cultural context of the study