The fifth generation (5G) wireless communication networks are being deployed worldwide from 2020 and more capabilities are in the process of being standardized, such as mass connectivity, ultra-reliability, and guaranteed low latency. However, 5G will not meet all requirements of the future in 2030 and beyond, and sixth generation (6G) wireless communication networks are expected to provide global coverage, enhanced spectral/energy/cost efficiency, better intelligence level and security, etc. To meet these requirements, 6G networks will rely on new enabling technologies, i.e., air interface and transmission technologies and novel network architecture, such as waveform design, multiple access, channel coding schemes, multi-antenna technologies, network slicing, cell-free architecture, and cloud/fog/edge computing. Our vision on 6G is that it will have four new paradigm shifts. First, to satisfy the requirement of global coverage, 6G will not be limited to terrestrial communication networks, which will need to be complemented with non-terrestrial networks such as satellite and unmanned aerial vehicle (UAV) communication networks, thus achieving a space-air-ground-sea integrated communication network. Second, all spectra will be fully explored to further increase data rates and connection density, including the sub-6 GHz, millimeter wave (mmWave), terahertz (THz), and optical frequency bands. Third, facing the big datasets generated by the use of extremely heterogeneous networks, diverse communication scenarios, large numbers of antennas, wide bandwidths, and new service requirements, 6G networks will enable a new range of smart applications with the aid of artificial intelligence (AI) and big data technologies. Fourth, network security will have to be strengthened when developing 6G networks. This article provides a comprehensive survey of recent advances and future trends in these four aspects. Clearly, 6G with additional technical requirements beyond those of 5G will enable faster and further communications to the extent that the boundary between physical and cyber worlds disappears.

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Towards 6G wireless communication networks: vision, enabling technologies, and new paradigm shifts

Unmanned aerial vehicles (UAVs) have found numerous applications and are expected to bring fertile business opportunities in the next decade. Among various enabling technologies for UAVs, wireless communication is essential and has drawn significantly growing attention in recent years. Compared to the conventional terrestrial communications, UAVs’ communications face new challenges due to their high altitude above the ground and great flexibility of movement in the 3-D space. Several critical issues arise, including the line-of-sight (LoS) dominant UAV-ground channels and induced strong aerial-terrestrial network interference, the distinct communication quality-of-service (QoS) requirements for UAV control messages versus payload data, the stringent constraints imposed by the size, weight, and power (SWAP) limitations of UAVs, as well as the exploitation of the new design degree of freedom (DoF) brought by the highly controllable 3-D UAV mobility. In this article, we give a tutorial overview of the recent advances in UAV communications to address the above issues, with an emphasis on how to integrate UAVs into the forthcoming fifth-generation (5G) and future cellular networks. In particular, we partition our discussion into two promising research and application frameworks of UAV communications, namely UAV-assisted wireless communications and cellular-connected UAVs, where UAVs are integrated into the network as new aerial communication platforms and users, respectively. Furthermore, we point out promising directions for future research.

Accessing From the Sky: A Tutorial on UAV Communications for 5G and Beyond

A compilation of UAV applications for precision agriculture

Himalayan glacier tongues are commonly debris covered and they are an important source of melt water. However, they remain relatively unstudied because of the inaccessibility of the terrain and the difficulties in field work caused by the thick debris mantles. Observations of debris-covered glaciers are therefore scarce and airborne remote sensing may bridge the gap between scarce field observations and coarse resolution space-borne remote sensing. In this study we deploy an Unmanned Aerial Vehicle (UAV) before and after the melt and monsoon season (May and October 2013) over the debris-covered tongue of the Lirung Glacier in Nepal. Based on stereo-imaging and the structure for motion algorithm we derive highly detailed ortho-mosaics and digital elevation models (DEMs), which we geometrically correct using differential GPS observations collected in the field. Based on DEM differencing and manual feature tracking we derive the mass loss and the surface velocity of the glacier at a high spatial accuracy. On average, mass loss is limited and the surface velocity is very small. However, the spatial variability of melt rates is very high, and ice cliffs and supra-glacial ponds show mass losses that can be an order of magnitude higher than the average. We suggest that future research should focus on the interaction between supra-glacial ponds, ice cliffs and englacial hydrology to further understand the dynamics of debris-covered glaciers. Finally, we conclude that UAV deployment has large potential in glaciology and it may revolutionize methods currently applied in studying glacier surface features.

High-Resolution Monitoring of Himalayan Glacier Dynamics Using Unmanned Aerial Vehicles

Unmanned aerial vehicles (UAVs) have found numerous applications and are expected to bring fertile business opportunities in the next decade. Among various enabling technologies for UAVs, wireless communication is essential and has drawn significantly growing attention in recent years. Compared to the conventional terrestrial communications, UAVs' communications face new challenges due to their high altitude above the ground and great flexibility of movement in the three-dimensional (3D) space. Several critical issues arise, including the line-of-sight (LoS) dominant UAV-ground channels and resultant strong aerial-terrestrial network interference, the distinct communication quality of service (QoS) requirements for UAV control messages versus payload data, the stringent constraints imposed by the size, weight and power (SWAP) limitations of UAVs, as well as the exploitation of the new design degree of freedom (DoF) brought by the highly controllable 3D UAV mobility. In this paper, we give a tutorial overview of the recent advances in UAV communications to address the above issues, with an emphasis on how to integrate UAVs into the forthcoming fifth-generation (5G) and future cellular networks. In particular, we partition our discussions into two promising research and application frameworks of UAV communications, namely UAV-assisted wireless communications and cellular-connected UAVs,where UAVs serve as aerial communication platforms and users, respectively. Furthermore, we point out promising directions for future research and investigation.

Accessing From The Sky: A Tutorial on UAV Communications for 5G and Beyond

This work evaluates the impact of integrating a hybrid solar chimney power plant (HSCPPS) into a medium voltage distribution grid in the Safawi area, Jordan. The HSCPPS can operate as a traditional solar chimney power plant system during the day and as a cooling tower during the night, achieving continuous system utilization. Real data from the distribution grid and CYME software are used to monitor the impact of integrating the HSCPPS to the grid over a 24‐hour duration. The impact of the integration step on the performance parameters of the grid corresponding to voltage profile, losses, power factor (PF), and voltage step are investigated. For each of these parameters, a comparison between the grid performance with and without the HSCPPS is carried out and demonstrated. The results show a maximum reduction of voltage deviation from the nominal value by around 0.9%, a maximum reduction in the losses by approximately 0.33%, and a reduction in the PF from 0.83 to 0.74 as the HSCPPS is set to supply only active power (unity PF). In addition, the voltage step test is carried out according to International Electrotechnical Commission 61000‐3. The results show that there is a safe margin, and the voltage step limits did not exceed 3% of the nominal voltage.

Analysis and feasibility of integrating a new and novel hybrid solar chimney power plant with a traditional electrical grid

In this paper radial basis function neural network (RBFNN) is used to extract total harmonics in converter waveforms. The methodology is based on p-q (real power-imaginary power) theory. The converter waveforms are analyzed and the harmonics over a wide operating range are extracted. The proposed RBFNN filtering training algorithms are based on an efficient training method called hybrid learning method — computation is systematic. The method requires small size network, very robust, and the proposed algorithms are very effective. The analysis is verified using MATLAB/SIMULINK simulation.

Harmonic content extraction in converter waveforms using radial basis function neural networks (RBFNN) and p-q power theory

Radial basis function neural networks (RBFNN) are used to dynamically identify harmonics content in converter waveforms based on p-q (real power-imaginary power) theory. The converter waveforms are analyzed and the harmonic contents are identified over a wide operating range. The proposed RBFNN filtering training algorithm are based on systematic and computationally efficient training method called hybrid learning method. The small size and the robustness of the resulted network reflect the effectiveness of the proposed algorithm. The analysis is verified using MATLAB simulation.

Dynamic harmonic identification in converter waveforms using radial basis function neural networks (RBFNN) and p-q power theory

The sensitivity and the highly connected modern power systems make Power quality problems a priority in these systems. Both utilities and consumers have essential role in dealing with these problems. It is utilities responsibility to provide a clean and reliable power. On the other hand, it is consumer’s responsibility to draw power with acceptable indices. In this Paper, the type of the consumer’s facility is chosen as a basis for managing power quality indices. In this paper, comprehensive power quality in Jordan Low-Voltage Electrical Power Grid is measured. The loads are divided into five categories: : (i) industrial loads, (ii) commercial loads, (iii) hospital loads, (iv) residential loads, and (v) office loads. Assuming each category will affect the grid in similar way, which will facilitate prediction of power quality problems. Also, this methodology will help proposing new regulation that governs the relation between utilities and consumers. The power quality indices considered in this paper are; THD, Crest factor, K-factor, Power factor, Harmonic to active power ratio, Voltage imbalance, and Frequency variations. The results show similar results for the loads with the same type. Also, the results show the correlation between the current total harmonic distortion and utility voltages and neutral-to-ground voltage, and between voltage and current imbalance.

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Investigation of Power Quality Indices in Jordanian Distribution Grid

Renewable Energy becomes a vital part in modern power system because of; continuous increase of energy demand, global regulations about Co2 emissions, and the slash of the renewable energy prices. Wind energy is a great choice for it is reliability and sustainability. Jordan is a small and ambitious country trying to embrace renewable energy. Jordan Wind Farm (JWF) is the first wind power generation project in Jordan was carried out in Tafilah city. JWF consists of 38 ×3 MW and is connected to 132kV network. Wind energy projects are expected to grow rapidly to fulfill the increasing demand on energy in Jordan. Modern wind turbines are equipped with power converters and permanent magnetic synchronous generators (PMSG). These converters will affect the power quality and harmonic content, which can affect the operation and the reliability of the electrical grid. This paper will study the impact of installing and operating type 4 wind turbines on power quality indices at 132 kv side. Field measurements of power quality indices in JWF substation at Point of Common Coupling, data analysis, and comparison between the measurements and internationals and national standards are carried out. This paper considers several indices such as THD, Crest factor, Harmonic to active power ratio, Voltage imbalance, and Frequency variations. The results show similar results for the loads with the same type. Also, the results show the correlation between the current total harmonic distortion and utility voltages and neutral-to-ground voltage, and between voltage and current imbalance. KeywordsWind turbine, Renewable energy, Harmonics, Power quality, Jordan.

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Eyad Almaita

Papers

Analysis and feasibility of integrating a new and novel hybrid solar chimney power plant with a traditional electrical grid

Harmonic content extraction in converter waveforms using radial basis function neural networks (RBFNN) and p-q power theory

Dynamic harmonic identification in converter waveforms using radial basis function neural networks (RBFNN) and p-q power theory

Investigation of Power Quality Indices in Jordanian Distribution Grid

Impact Study of Wind Generation on power quality of Electrical Power Grid (Jordan Wind Farm Case Study)