We highlight research issues for wireless networking in aerial systems consisting of multiple small autonomous drones. Among these challenges are video streaming, synchronization, security and safety, and interference management.
Mobile robots in explorer missions need to charge their batteries from time to time. Different policies for coordinated recharging in teams of robots are evaluated.
In mobile communication systems, like UMTS or WLAN, the transmissions of different mobile devices interfere with each other. For example, when a mobile device transmits signals to its base station, other mobile devices transmitting on the same frequency band cause interference at that base station, which in turn may result in decoding errors in the intended signal. This form of interference becomes more and more relevant with the increasing number of wireless devices, and defines what is known as an interference-limited network. The number of incorrectly decoded bits per unit time is the bit error rate in the network.
Time synchronization is an essential building block in wireless sensor networks but is challenging due to low-precision oscillators and limited computational power of cheap devices. A novel synchronization solution for such scenarios is now proposed by Wasif Masood together with his advisors Christian Bettstetter and Jorge F. Schmidt from the University of Klagenfurt.
Written by Evsen Yanmaz. Edited by Christian Bettstetter. Small drones become increasingly popular for civil applications, including production of movies and delivery of important goods. The wireless communications and networking of drones is an essential building block in such systems. Lakeside Labs researchers have been working in this domain for several years; now they wrote a comprehensive survey article on the characteristics and requirements of drone networks.
Modern airplanes are equipped with hundreds of embedded sensors and actuators necessary for structural health monitoring, aircraft control, and passenger and crew assistance. These devices are typically interconnected by wires. Using wireless connections instead of wires improves flexibility of installations and reduces the airplane’s weight. Researchers from Airbus Group Innovations have been working on this topic for several years. An ongoing joint project with the University of Klagenfurt and Lakeside Labs develops and tests such in-cabin networks with focus on their robustness against undesired interference.
Synchronization algorithms based on the theory of pulse-coupled oscillators are evaluated on programmable radios. It is experimentally demonstrated that the stochastic nature of coupling is a key ingredient for convergence to synchrony. We propose a distributed algorithm for automatic phase rate equalization and show that synchronization precisions below one microsecond are possible.
The problem of finding a consensus in a group of people occurs in many social contexts. In a similar way, distributed algorithms for consensus play an important role in networked computing and communication systems if centralized decision making is difficult or impossible. Each entity in such a system processes only local information obtained from its neighbors and ideally performs only simple computations. Despite this simplicity, the process of consensus building should be robust against different types of disturbance, such as faulty entities, noise, and communication errors. A research team with members from Klagenfurt and Genoa has now analyzed the robustness of a special class of consensus algorithms, namely binary consensus, in which all entities must eventually agree on one out of two possible values. The motivation for their study is as follows: Some binary consensus algorithms that work well in noiseless and error-free networks—such as the well-known Gacs-Kurdyumov-Levin algorithm—show convergence problems in networks with disturbances. In turn, some other algorithms that are inferior in noiseless and error-free networks may actually improve their performance with the …
New packages for the Robot Operating System (ROS) are available for autonomous exploration of unknown environments using collaborating mobile robots equipped with cameras. The software offers wireless ad hoc communications between robots, merging of maps from different robots, and coordinated selection of exploration frontiers. A prototype with four robots was built that demonstrates its functionality in an indoor environment.
Wireless networks are often modeled using tools from stochastic geometry. A team of researchers from Klagenfurt, Athens, and Notre Dame now contributed to these tools by solving general sum-product functionals for Poisson point processes. Link outage probabilities are derived for networks with interference and Nakagami fading.