Modeling the dynamic properties of communication channels in UAV-based networks based on spectral piecewise linear approximation method

This work is devoted to the application of methods for approximating signals and characteristics based on continuous piecewise linear functions (CPLF) for modeling wireless radio communication channels using unmanned aerial vehicles (UAVs). The relevance and prospects of using this class of aircraft as part of flying ad-hoc networks (FANET) for transmitting high-speed information in "smart cities" are shown. The problem of these networks is also noted, due to uncertain reliability and quality of wireless communication, associated with multipath propagation of signals and a number of other factor

Securing NextG networks with physical-layer key generation: A survey

As the development of next-generation (NextG) communication networks continues, tremendous devices are accessing the network and the amount of information is exploding. However, with the increase of sensitive data that requires confidentiality to be transmitted and stored in the network, wireless network security risks are further amplified. Physical-layer key generation (PKG) has received extensive attention in security research due to its solid information-theoretic security proof, ease of implementation, and low cost. Nevertheless, the applications of PKG in the NextG networks are still in the preliminary exploration stage. Therefore, we survey existing research and discuss (1) the performance advantages of PKG compared to cryptography schemes, (2) the principles and processes of PKG, as well as research progresses in previous network environments, and (3) new application scenarios and development potential for PKG in NextG communication networks, particularly analyzing the effect and prospects of PKG in massive multiple-input multiple-output (MIMO), reconfigurable intelligent surfaces (RISs), artificial intelligence (AI) enabled networks, integrated space-air-ground network, and quantum communication. Moreover, we summarize open issues and provide new insights into the development trends of PKG in NextG networks

Adoption of vehicular ad hoc networking protocols by networked robots

This paper focuses on the utilization of wireless networking in the robotics domain. Many researchers have already equipped their robots with wireless communication capabilities, stimulated by the observation that multi-robot systems tend to have several advantages over their single-robot counterparts. Typically, this integration of wireless communication is tackled in a quite pragmatic manner, only a few authors presented novel Robotic Ad Hoc Network (RANET) protocols that were designed specifically with robotic use cases in mind. This is in sharp contrast with the domain of vehicular ad hoc networks (VANET). This observation is the starting point of this paper. If the results of previous efforts focusing on VANET protocols could be reused in the RANET domain, this could lead to rapid progress in the field of networked robots. To investigate this possibility, this paper provides a thorough overview of the related work in the domain of robotic and vehicular ad hoc networks. Based on this information, an exhaustive list of requirements is defined for both types. It is concluded that the most significant difference lies in the fact that VANET protocols are oriented towards low throughput messaging, while RANET protocols have to support high throughput media streaming as well. Although not always with equal importance, all other defined requirements are valid for both protocols. This leads to the conclusion that cross-fertilization between them is an appealing approach for future RANET research. To support such developments, this paper concludes with the definition of an appropriate working plan

Near-Space Communications: the Last Piece of 6G Space-Air-Ground-Sea Integrated Network Puzzle

This article presents a comprehensive study on the emerging near-space communications (NS-COM) within the context of space-air-ground-sea integrated network (SAGSIN). Specifically, we firstly explore the recent technical developments of NS-COM, followed by the discussions about motivations behind integrating NS-COM into SAGSIN. To further demonstrate the necessity of NS-COM, a comparative analysis between the NS-COM network and other counterparts in SAGSIN is conducted, covering aspects of deployment, coverage, channel characteristics and unique problems of NS-COM network. Afterwards, the technical aspects of NS-COM, including channel modeling, random access, channel estimation, array-based beam management and joint network optimization, are examined in detail. Furthermore, we explore the potential applications of NS-COM, such as structural expansion in SAGSIN communication, civil aviation communication, remote and urgent communication, weather monitoring and carbon neutrality. Finally, some promising research avenues are identified, including stratospheric satellite (StratoSat) -to-ground direct links for mobile terminals, reconfigurable multiple-input multiple-output (MIMO) and holographic MIMO, federated learning in NS-COM networks, maritime communication, electromagnetic spectrum sensing and adversarial game, integrated sensing and communications, StratoSat-based radar detection and imaging, NS-COM assisted enhanced global navigation system, NS-COM assisted intelligent unmanned system and free space optical (FSO) communication. Overall, this paper highlights that the NS-COM plays an indispensable role in the SAGSIN puzzle, providing substantial performance and coverage enhancement to the traditional SAGSIN architecture.Comment: 28 pages, 8 figures, 2 table

Energy and spectrum efficient blind equalization with unknown constellation for air-to-ground multipath UAV communications

In unmanned aerial vehicle (UAV) communications, frequency-selective fading can severely deteriorate the quality of transmitted signal by generating undesired and disordered constellation diagrams due to scatters in the air-to-ground (ATG) mutipath channels. In this paper, we propose a low-overhead blind equalization method to combat frequency-selective fading in air-ground multipath UAV channels. Specifically, a pre-equalization method is proposed based on a constant modulus algorithm to restore the contour of the constellation diagram. Moreover, the similarity measure function and the difference measure function are derived using template matching to identify the constellation of M-ary quadrature amplitude modulation. Furthermore, we propose a weighted constant cross algorithm (WXA) to reduce the residual mean square error and construct a cross-shaped modulus value, by utilizing the statistical information of the identified normalized standard constellation diagrams and the equalizer output decision symbols’ weighting value. The proposed method requires less information and no training sequences and pilots, therefore, if achieves energy and spectrum efficient ATG multipath UAV communications. Simulation results show that the proposed WXA algorithm can reduce the residual mean square error convergence value between -22dB and -25dB, making it very useful for the equalization of the frequency-selective fading channel in typical UAV communication scenarios

Wireless sensing: Material identification and localization

Wireless signals are everywhere around us, and they have truly revolutionized the world by all standards. When one thinks of this revolution, one envisions the advances in wireless communication—TV broadcasts, FM radios, WiFi, Bluetooth, cellular mobile phones, and even wireless chips inside the human body. What gets less appreciated, however, is that wireless signals can also be a powerful sensor. The fact that wireless signals touch and penetrate all objects in our environment, and bounce back, make them a powerful lens to view our world through. This thesis focuses on using wireless signals as sensors. We will explore how modifications to wireless signal propagation can reveal the physical properties of the materials that these signals have passed through. This enables identification of materials without touching them or performing any chemical analysis on them. We will show the ability to distinguish between closely related liquids, such as Pepsi and Coca-Cola, or distilled water and mineral water, by simply passing wireless signals through the liquids, and analyzing the signals that emerge on the other side. The propagation delay of wireless signals when passing through air can reveal the distance between a transmitter and a receiver. We show how this primitive can be extended for localization with applications to sports, battlefields, and emergency response. Through modifications to the distance measurement mechanisms, we show how localization is possible even when wireless devices are constantly under motion. We end by discussing future directions in which both of these sensing techniques can be extended. Under the right conditions, it might be possible to localize an object to 5mm precision with applications in robotic machines, augmented reality, and virtual reality. We then discuss the possibility of using reflections of wireless signals, for example, to determine soil moisture content in agricultural fields

Autonomous Drone Network: Non-Intrusive Control and Indoor Formation Positioning

The Teal Group estimated worldwide drone expenditure in 2013 to be $5.2 billion. Since then, worldwide drone expenditure has risen considerably, with the International Data Corporation (IDC) forecasting worldwide spending on drones to total$12.3 billion in 2019, with a compound annual growth rate (CAGR) forecast of 30.6% to 2022. As of 2019, Goldman Sachs report military applications account for 70% of the total spend with consumer applications accounting for 17%, and commercial/civil applications accounting for the remaining 13% where the latter are showing the fastest growth. Applications in construction, agriculture, offshore oil and gas, policing, journalism, border protection, mining and cinematography are predicted to see the greatest drone investment. As the demands increase, and particularly for applications that are time critical or that span large geographical areas, the single drone solution may be inadequate due to its limited energy and payload. A multiple drone solution, where the drones are networked and the drone’s position is established by GPS (global positioning system), is able to complete demanding applications more efficiently. In such systems however, the accuracy of GPS can be substantially compromised when deployed near tall buildings, trees, or bridges or if deployed indoors or underground. In this research, a drone position determination (DPD) algorithm, is proposed to overcome the shortcomings of GPS when satellite signals are compromised. An ad-hoc Wi-Fi network of autonomous quadcopter drones is constructed, as a platform to demonstrate the algorithm performance. To complement the DPD algorithm calculation, a method to estimate the distance flown, and also estimate the complete flightpath of a drone by considering the interaction of the angular velocities of a quadcopter’s four rotors (AVQR), is presented. The flight plan to examine the AVQR algorithm yields results enabling the distance flown to be calculated to an accuracy of 95%