Recent Advances in Communications and Networking Technology (Formerly Recent Patents on Telecommunication) (Discontinued) - Volume 6, Issue 2, 2017

History: The battle for achieving the Sustainable Development Goals (SDGs) of United Nations Agenda 2030, will be won at the city level. All countries are addressing the SGDs at the city level by implementing smart city initiatives. Smart cities take advantage of ICT systems for improving city' system performance and optimize its resources. Objective: The ultimate objective is to improve the citizen quality of the life while the sustainability at social, economic and environmental level is guaranteed. For leading with the complexity of the urban problems ICT-enable systems such as massive data analysis in real time can be used as an instrument for supporting the decision-making process. Method: In that sense, this paper proposes a tool, which helps decision makers, to design and implement smart city initiatives. The tool is an online platform capable of doing three-dimensional data analysis of a repository of smart city initiatives. Results: The platform makes use of the OLAP technology to produce the 3D analysis and it showed to be a very powerful tool for decision-makers which want to know more about smart cities projects and learn from past experiences to make always the best decisions based on evidence based information.

Background: Present study inspects the profiles of electric Dipole Moment (DPM) and polarizability (αp) of impurity doped GaAs Quantum Dots (QDs) in the presence of noise. Objective: Noise term maintains a Gaussian white character and it has been introduced to the system via two different pathways; additive and multiplicative. In view of a comprehensive analysis, modulation of DPM and αp has been scrutinized along with the variations of several relevant quantities such as electric field, magnetic field, confinement potential, dopant location, dopant potential, noise strength and aluminium concentration (only for AlxGa1-xAs QD). Methods: Application of noise almost invariably reduced the magnitude of αp and DPM from that of noisefree condition. However, the extent to which the said properties are altered depends on the noise strength domain and the pathway through which noise is applied. It can therefore be inferred that introduction of noise diminished the asymmetric nature of the system to a noticeable extent. Research: Moreover, the extent of drop in the asymmetric character of the system was found to be more with multiplicative noise than its additive analogue. Thus, the mode of application of noise also appears important in harnessing the polarizability and dipole moment of the system. Conclusion: The outcomes of the study delineate viable routes to tune the dipole moment and polarizability of doped QD system, particularly in presence of noise.

Background: Currently, spectrum sharing policies specify inflexible spectrum access controls such as exclusion zones and maximum transmit powers based upon statistical characterizations of all potential operating environments. The rules for preventing interference are influenced by low probability events and are set at conservative operating levels. Consequently, spectrum sharing potential in the majority of operating conditions is limited by a small percentage of relatively rare conditions, which results in inefficient spectrum usage. Objective: This paper adopts a probabilistic view of dynamic spectrum sharing systems. Specifically, establishing in situ probabilistic reasoning reasoning within the context of a specific spectrum access environment enables sharing systems to adapt to local conditions and uncertainties. Regulators and spectrum users can establish spectrum access rules defining acceptable levels spectrum access risks. Method: The paper develops a probabilistic reasoning model using Bayesian Networks to encode the phenomenology of the communications channels and systems, and also represent the cause--128;and--128; effect nature of dynamic spectrum sharing. This approach allows systems to infer permitted actions (e.g., maximum transmit power) based on incomplete knowledge and established interference risk thresholds. Results: Simulation results demonstrate that situation--128;specific probabilistic reasoning combined with risk--128;constrained spectrum access potentially enables greater spectrum sharing potential. Sharing systems can increase transmit powers for greater channel capacity or increase network density over existing spectrum sharing approaches. Situational uncertainty can also be reduced as sharing systems observe the operating environment, leading to further performance gains. Conclusions: The results of this paper demonstrate significant potential for probabilistic reasoning and risk constrained spectrum sharing for increasing spectrum access.

Background: Owing to rapid development of hardware components and reduction in prices, Unmanned Ariel Vehicles (UAVs) are becoming ubiquitous including application to airborne ad-hoc communication relay stations. Quadcopters are one class of UAVs, which have particularity seen rapid growth due to their versatility. Since quadcopters are inherently unstable and hard to stabilize by human operator, they need automated attitude stabilization. However, altitude stabilization around desired height is often overlooked, while it has an important role in optimal location for airborne communication relay. Objective: The paper addresses the issue by developing controllers for UAV hovering. The proposed approach can then be extended to arbitrary height (possibly with different sensor setup). Method: For the development of control schemes, two approaches were used: PID and Neural network (NN) based one. For the development of NN (i.e. learning phase) Gazebo simulation environment was used essentially modeling the human driver. Developed approaches were tested both in simulation and in real-world scenario on AR.Drone 1.0 and AR.Drone 2.0 UAVs. Results: Obtained indoor results demonstrated PID accuracy of 1 cm with overshoot of 2.7% and settling time of 3.75 s, while NN demonstrated 2.1 cm, 1%, and 8.4 s, respectively. Outdoor testing was also performed with similar result trends. Conclusion: Both developed controllers demonstrated good results (indoor and outdoor) and could be used in real world scenario, but NN due to its favorable characteristics (i.e. human driver modelling) and straightforward development phase (as compared to PID which involves lot of trial-and-error) is preferred.

Background and Objective: Today, Wi-Fi technology is practically being used as a default connectivity solution for many new technologies and concepts like Internet of Things (IoT) and Smart City. The design of Wi-Fi network is a complex problem, where it is necessary to decide about the location and number of access points in given indoor or outdoor environment. Method and Results: In this paper, the measurement results of Wi-Fi signal in the indoor-to-outdoor building environment are investigated and possible sources of signal loss in the examined Wi-Fi channel are pointed out and discussed. The influence of human hand signal absorption is examined by comparison of the measurements performed by professional equipment with the ones obtained by a smartphone. We considered different receiver positions as well as the change of transmitter antenna gain with respect to the receiver height. Conclusion: The gain correction was estimated, and results showed a good agreement between the calculated and measured power levels at the receiver.