A CDMA Based Approach for QoS Improvement in Intra-Aircraft Wireless Sensor Networks (WSN) 2024-26-0435

Aviation industry is striving to leverage the technological advancements in connectivity, computation and data analytics. Scalable and robust connectivity enables futuristic applications like smart cabins, prognostic health management (PHM) and AI/ML based analytics for effective decision making leading to flight operational efficiency, optimized maintenance planning and aircraft downtime reduction. Wireless Sensor Networks (WSN) are gaining prominence on the aircraft for providing large scale connectivity solution that are essential for implementing various health monitoring applications like Structural Health Monitoring (SHM), Prognostic Health Management (PHM), etc. and control applications like smart lighting, smart seats, smart lavatory, etc. These applications help in improving passenger experience, flight operational efficiency, optimized maintenance planning and aircraft downtime reduction. WSNs used for such applications are expected to provide robust and reliable communication performance. However, onboard WSNs, when deployed, must co-exist with other wireless devices and networks based on Wi-Fi and Bluetooth technologies. Sharing of the ISM frequency band (2.4 GHz) among these networks makes the co-existence problem more challenging and has a significant impact on the Quality of Service (QoS) in terms of throughput, latency and Packet Error Rate (PER) of WSN. In addition, they are subjected to additional electromagnetic interference from other electronic and avionic systems onboard aircraft. There are various channel management, priority-based scheduling and time-sharing techniques that are deployed currently to address the co-existence problem. However, these methods perform a trade-off among one or more operational parameters like channel bandwidth, number of nodes per channel, throughput, latency, PER, etc. of WSN. Code Division Multiple Access (CDMA) technique is a proven one in cellular networks for providing reliable interference free communication performance especially in large scale networks. This paper evaluates the feasibility of deploying CDMA for WSN onboard aircraft. A CDMA based communication schema is proposed and simulated for a WSN operating as per IEEE 802.15.4 protocol. The communication performance of the WSN is evaluated in presence of interference from Wi-Fi devices by analyzing the QoS parameters like operational bandwidth, Bit-Error Rate (BER) and Process Gain for various combinations of Pseudo Random code generation algorithms and modulation methods through simulation. Simulations results are evaluated against the desired performance level for a reference use case application. Improvement opportunities are identified and areas for future research are proposed.