Estimation and Analysis of Free Space Optics Link Margin for Quality Based Network Routing

Free space optics (FSO) is a revolution in communication technology which uses light in free space for transmission. FSO systems are used for high data rate communication between two remote sites over distances up to several kilometers. It solves the problem between the client/user and ber-optic back-haul solving the last-mile problem. They are appealing for abroad application areas such as, ber back-up, local area network (LAN)-to- LAN connectivity, disaster recovery, backhaul for wireless cellular networks, high definition TV and wireless video surveillance/monitoring etc. The link reliability particularly in long range communication is limited mainly due to atmospheric turbulence-induced fading and sensitivity to weather conditions. The main consideration in the FSO design is the availability of link for different atmospheric conditions and providing a reliable quality of transmission (QoT) to the end user. An FSO network with distance based routing and wavelength assignment (RWA) technique does not provide any information about the current state of network, leading to a non-reliable communication. Based on the above the following analysis is been proposed: ●This work deals with the estimation of FSO link in different parts of India using Link Margin (LM). Here the meteorological data of various cities has been collected which evaluates the availability of the link for different attenuations in channel. ● FSO network with an adaptive routing and wavelength assignment (RWA) technique based on LM is proposed which selects the connection with higher availability rather than shortest distance. The overall network performance is being evaluated in terms of blocking probability (BP) based on network load and available link wavelengths. The estimated results can provide more knowledge about the reliability and deploy- ment of FSO network. In short, this thesis work estimates the Free space optics LM for Quality based network routing

Time-Series Studies of Particulate Matter

Studies of air pollution and human health have evolved from descriptive studies of the early phenomena of large increases in adverse health effects following extreme air pollution episodes, to time-series analyses and the development of sophisticated regression models. In fact, advanced statistical methods are necessary to address the many challenges inherent in the detection of a small pollution risk in the presence of many confounders. This paper reviews the history, methods, and findings of the time-series studies estimating health risks associated with short-term exposure to particulate matter, though much of the discussion is applicable to epidemiological studies of air pollution in general. We review the critical role of epidemiological studies in setting regulatory standards and the history of PM epidemiology and time-series analysis. We also summarize recent time-series results and conclude with a discussion of current and future directions of time-series analysis of particulates, including research on mortality displacement and the resolution of results from cohort and time-series studies

An efficient reconfigurable workload balancing scheme for fog computing network using internet of things devices

Nowadays a huge amount of data has been communicated using fog nodes spread throughout smarty cities. the communication process is performed using fog nodes which are co-located with cellular base stations (BSs) that can move the computing resources close to internet of things (IoT) devices. In smart cities, a different type of data flow has been communicated through IoT devices. The communication process performs efficiently using the remote cloud. The IoT devices very close to the BS can communicate data without using fog nodes. Due to these phenomena, workload unbalancing occurs in IoT devices communicating in fog computing networks. Hence, it generates communication and computing latency. The task distribution process between the IoT devices is unbalanced. Hence, congestion and loss of information occur in fog computing network. A proposed reconfigurable load balancing algorithm (RLBA) is efficiently balancing the workload by reconfigurable communication channels and deviates the task with respect to the BS locations, IoT devices density and load IoT devices in each fog nodes in a network to minimize the communication and computing latency. As per the performance analysis, the proposed algorithm shows better performance as compared to conventional methods’ average latency ratio, communication latency ratio, computing load and traffic load

How Rapidly Should Developing Countries Implement Intelligent Transportation Systems (ITS) to Solve the Growing Urban Traffic Congestion Problem?

Many newly developing countries are growing rapidly. One example is India, currently the second most populous country in the world. According to the Indian Ministry of Urban Development, from 1981 to 2001, the population in six major Indian cities increased twofold while motor vehicles increased eightfold. Such rapid growth in vehicles without a comparable growth in transportation infrastructure leads to increasing traffic congestion. Cities in India are already considered congested today, and are going to be even more congested in the coming years since the rate of urbanization in India in 2006 was only 29% and is expected to grow to 41% by 2030 [1]. The corresponding rates for the world and Asia as a whole are projected to be 61% and 55%, respectively

Climate change and disaster impact reduction

Based on papers presented at the 'UK - South Asia Young Scientists and Practitioners Seminar on Climate Change and Disaster Impact Reduction' held at Kathmandu, Nepal on 5-6 June, 2008

The impact of visibility range and atmospheric turbulence on free space optical link performance in South Africa.

Doctoral Degree. University of KwaZulu-Natal, Durban.In the recent years, the development of 5G and Massive Internet of Things (MIoT) technologies are fast increasing regularly. The high demand for a back-up and complimentary link to the existing conventional transmission systems (such as RF technology) especially for the “last-mile” phenomenon has increased significantly. Therefore, this has brought about a persistent requirement for a better and free spectrum availability with a higher data transfer rate and larger bandwidth, such as Free Space Optics (FSO) technology using very high frequency (194 −545 ) transmission system. There is currently unavailable comprehensive information that would enable the design of FSO networks for various regions of South Africa based on the impact of certain weather parameters such as visibility range (mainly in terms of fog and haze) and atmospheric turbulence (in terms of Refractive Index Structure Parameter (RISP)) on FSO link performance. The components of the first part of this work include Visibility Range Distribution (VRD) modeling using suitable probability density function (PDF) models, and prediction of the expected optical attenuation due to scattering and its cumulative distribution and modeling. The VRD modelling performed in this work, proposed various location-based PDF models, and it was suggested that the Generalized Pareto distribution model best suited the distributions of visibility in all the cities. The result of this work showed that the optical attenuation due to scattering within the coastal and near-coastal areas could reach as high as 169 / or more, while in the non-coastal areas it varies between 34 / and 169 /, which suggests significant atmospheric effects on the FSO link, mostly during the winter period. The BER performance analysis was performed and suitable mitigating techniques (such as 4 × 4 MIMO with BPSK and L-PPM schemes) were suggested in this work. The general two-term exponential distribution model provided a good fit to the cumulative distribution of the atmospheric attenuation due to scattering for all the locations. In order to ascertain how atmospheric variables contribute or affect the visibility range, which in turn determines the level of attenuation due to scattering, a time series prediction of visibility using Artificial Neural Network (ANN) technique was investigated, where an average reliability of about 83 % was achieved for all the stations considered. This suggests that climatic parameters highly correlate to visibility when they are all combined together, and this gave significant predictions which will enable FSO officials to develop and maintain a strategic plan for the future years. The modules of the second part of this work encompass the determination of the Atmospheric Turbulence Level (ATL) for each of the locations in terms of RISP (2) and its equivalent scintillation index, and then the estimation of the optical attenuation due to scintillation. The cumulative distributions of the optical attenuation due to scintillation and its modeling were also carried out. This research work has been able to achieve the prediction of the ground turbulence strength (through the US-Army Research Laboratory (US-ARL) Model) in terms of RISP using climatic data. In an attempt to provide a more reliable study into the atmospheric turbulence strength within South Africa, this work explores the characteristic behavior of several meteorological variables and other thermodynamic properties such as inner and outer characteristic scales, Monin-Obhukov length, potential temperature gradient, bulk wind shear and so on. According to the predicted RISP from meteorological variables (such as temperature, relative humidity, pressure, wind speed, water vapour, and altitude), location-based and general attenuation due to scintillation models were developed for South Africa to estimate the optical attenuation. The attenuation due to scintillation results show that the summer and autumn seasons have higher ATL, where January, February and December have the highest mean RISP across all the locations under study. Also, the comparison of the monthly averages of the estimated attenuations revealed that at 850 nm more atmospheric turbulence with specific attenuations between 21.04 / and 24.45 / were observed in the coastal and near-coastal areas than in the non-coastal areas. The study proposes the two-term Sum of Sine distribution model for the cumulative distribution of the optical attenuation based on scintillation, which should be adopted for South Africa. The obtained results in this work for the contributions of scattering and turbulence to the optical link, and the design of the link budget will serve as the major criteria parameters to further compare the outcomes of these results with that of the available terrestrial FSO systems and other conventional transmission systems like RF systems

Rain Attenuation Modelling and Prediction for Optical Wireless Communication Systems in Durban, South Africa.

Masters Degree. University of KwaZulu-Natal, Durban.The continuous demand for more reliable wireless communication systems with extremely high data rates has accelerated various aspects of research topics to be able to meet future needs. One of the most crucial topics in the field of communication is free-space optics (also known as optical wireless communication). It is well-known that the performance of any optical wireless communication system is strongly influenced by the atmospheric conditions in a given environment. In foggy, rainy, and clear weather conditions, optical signals are known to be attenuated due to scattering. The received signal is diminished in the presence of snow, rain, or even haze. Rain and clear weather conditions will be the focus of this research as there is hardly snow or haze in South Africa, especially Durban since it is a subtropical region. In this research work, rain attenuation modelling and prediction will be done using an empirical method based on the relationship between the observed attenuation distribution and the related observed rain intensity distribution at a 30 second integration period. A disdrometer is used to obtain the rain intensity, and a power meter is used to log the received signal power level every 30 seconds to evaluate the influence of rain on the signal transmitted. The International Telecommunication Union (ITU-R) recommends targeting for 99.99 % system availability; as a result, the rainfall rate (R0.01) in the research region must be estimated for 0.01 percent of the time. The rain intensity and raindrop size distribution (DSD) modelling is then performed from the empirical method, obtaining R0.01 for Durban for all months throughout the experiment period. Using the disdrometer diameter ranges, the spherical droplet assumption is used to estimate the scattering parameters for frequencies between 2 GHz and 1000 GHz. The relationship between the received signal level and the intensity of rain for a particular weather condition at a specific time is then obtained. Transceivers with a fixed length of 7 meters between them, due to shortage of material such as the fiber cables to link the transceivers to the computer for data monitoring and logging, and for accurate alignment, were used to conduct these experiments. This relationship is compared against the French model at a wavelength of 850 nm. The main results obtained from this work reveal that there are extremely high attenuation values compared to the French model, which thus calls for further investigation to provide the optimum model that can accurately predict these effects for reliable optical wireless communications in Durban, South Africa

Between Aastha and Zee: Mystery of the Missing Market for a Weather Channel

Until a few decades ago, Doordarshan was the only channel which would broadcast TV programmes in black-&-white and that too for a few hours. It was a pure public good then, offered free of cost by the government. Today, however, from Aastha to Zee there are hundreds of dedicated private channels competing to offer news, sports, entertainment, and spirituality for a price. And still, there is not a single channel which is dedicated to 24-hour weather forecast. This is a clear case of market failure of the free enterprise system. The missing market for an exclusive weather channel is the result of perceived marginal private benefit to millions of individual farmers and other stakeholders being much less than the marginal social benefit accruing to the nation as a whole. Every year unanticipated weather patterns cause huge economic losses to food and agriculture and other industries and cause a great number of fatalities too. If IMD gives quick alerts to pilots and airports, and some private forecasters plan to give medium to long-term forecast to cricketing and other events, the same can be done for millions of farmers and other stakeholders of the economy. Therefore, government and the corporate sector may offer a 24-hour TV channel for weather forecast in the form of public private partnership (PPP). The weather forecasting infrastructure and data may come from 1 Professor and graduate student; respectively, Indian Institute of Management Ahmedabad (IIMA) government institutions such as IMD, C-DAC, and ISRO; professional content delivery and services of weathermen who deliver the content may come from TV media firms; and the break- even revenue may come through CSR activities of the corporate sector

Urban Air Mobility Market Study

The Booz Allen Team explored market size and potential barriers to Urban Air Mobility (UAM) by focusing on three potential markets – Airport Shuttle, Air Taxi, and Air Ambulance. We found that the Airport Shuttle and Air Taxi markets are viable, with a significant total available market value in the U.S. of $500 billion, for a fully unconstrained scenario. In this unconstrained best-case scenario, passengers would have the ability to access and fly a UAM at any time, from any location to any destination, without being hindered by constraints such as weather, infrastructure, or traffic volume. Significant legal and regulatory, weather, certification, public perception, and infrastructure constraints exist, which reduce the market potential for these applications to only about 0.5$2.5 billion, in the near term. However, we determined that these constraints can be addressed through ongoing intra-governmental partnerships, government and industry collaboration, strong industry commitment, and existing legal and regulatory enablers. We found that the Air Ambulance market is not a viable market if served by electric vertical takeoff and landing (eVTOL) vehicles due to technology constraints but may potentially be viable if a hybrid VTOL aircraft are utilized