WAIC Compatible Communication System for Current Sensing in Aircrafts
The Ampwise platform offers secure, autonomous and resilient wireless communication, for the periodic measurement of electrical return current in aircrafts. The paper briefly describes the challenges, the chosen approaches and solutions and preliminary results. It summarises the analysis of the main application requirements, the operational parameters and constraints (including size and weight), as well as the basic specification of the system and its components (physical layer, MAC and application protocols, power supply, current sensor, etc.). The sensor nodes are installed for the entire lifetime of the aircraft. While the time requirements of the application are not very stringent, the availability of the data is of utmost importance for the safety, performance and operational efficiency of new generation commercial aircrafts. The high-level architecture and its interfaces, the principles of the sensor acquisition and data transmission complete the system description.
The ultra low power wireless communication system is built on top of a physical layer operating in the 4.2-4.4 GHz Wireless Avionics Intra-Communications (WAIC) band dedicated to local wireless communications within aircrafts. The communication system also comprises the protocol stack offering services to the target applications, such as periodic transmission of acquired samples, security establishment, synchronization, redundancy and robustness support.
The Ampwise network is primarily made of energy autonomous wireless current sensor nodes (SN) aiming at remotely monitoring the return electrical current in the airframe of modern commercial aircrafts. It is structured around a Wireless Data Concentrator (WDC) that interconnects to the aircraft systems and its avionics, up to 300 autonomous SNs that are installed near the aircraft electrical lines. A second WDC monitors the activity of the first WDC to provide redundancy for network orchestration and fault-tolerance. The SNs and the pair of WDCs form a cell, which uses a radio communication protocol to interact, exchange data and commands, while meeting real-time properties and exhibiting robustness and resilience to the adversarial operating conditions of the aeronautic environments, in particular propagation and interference. Several cells can coexist in an aircraft, to cover the entire airframe. The sensor nodes and the WDC comprise an antenna and a transceiver, which, due to the absence of WAIC compliant hardware, is currently made of a 2.4 GHz radio coupled with a frequency converter.
The Ampwise SN comprises an energy harvesting device, for which several options have been considered, e.g. thermal energy generator and current flow harvesters. The paper concludes by giving an evaluation of the power balance between the energy consumption and the potential generation of the energy harvester.
The AMPWISE project is partly funded by the European Union’s H2020 through Clean Sky 2 Programme under Grant Agreement 785495.