Priority queuing model for analysis of network traffic in flight operations of commercial aircraft

All electric Aircraft and Intelligent systems is the future trend of Avionics. It is very important to monitor various health parameters of the aircraft in order to ensure safety of passengers, crew and operators and to improve reliability of aircraft. Even as the aerospace community is working on multiple technologies like EHM, SHM, AHM and IVHM to monitor health parameters, there are challenges in selecting and placing the sensors optimally and establishing seamless communication between different subsystem monitoring units. This requires increased number of sensors and with the existing wired network in the aircraft, deploying and managing a scalable sensor network becomes more complicated. It is proposed to develop WSN onboard aircraft to simplify configurability and maintainability for a scalable network. Developing new WSN comes with design challenges for selection of topologies, frequency allocation for wireless nodes and meeting the performance metrics in terms of network throughput, system latency and reliable data. Since performance metrics depends on the traffic characteristics, a mathematical model for network traffic analysis for the proposed WSN is presented. Priority Queueing theory has been used in the model to handle different priority levels of multi-typed and multi-rated sensor data in an avionics network. Both preemptive and non-preemptive priority handling policies are used to define mathematical expressions for network traffic. The policies enable comparative analysis of network performance in terms of qualifying system response to low priority data in presence of those belonging to high priority class. The model is applied to a representative network with 6 sensors of different priority levels and variable data rates to assess QoS parameters of the network, in specific (i) Average system response and (ii) Waiting time. The network simulation platform presented in the paper serves as a tool to assess feasibility of MAC protocol selection for different scenarios in wireless avionic communications.