Wireless sensor networks need accurate time synchronization for data consistency and coordination. Although the existing algorithms for time synchronization offer very good accuracy, their energy consumption is high, and distant nodes are poorly synchronized. We propose a Recursive Time Synchronization Protocol (RTSP) which accurately synchronizes all the nodes in a network to a global clock using multi-hop architecture in an energy-efficient way. It achieves better performance due to the MAC-layer time-stamping based on Start of Frame Delimiter byte, infrequent broadcasts by a dynamically elected reference node, compensation of the propagation delay and adjustment of the timestamps at each hop, estimation of the relative skew and offset using least square linear regression on two data points (2LR), adaptive re-synchronization interval, aggregation of the synchronization requests, and energy awareness. A detailed analysis of the sources of errors is also provided. Simulation results show that the RTSP can achieve an average accuracy of 0.3 microseconds in a large multi-hop flat network while using five-times lesser energy than that of FTSP in the long run and performs even better in a clustered network where it can achieve an average accuracy of 0.23 microseconds while using seven-times lesser energy.

RTSP: An Accurate and Energy-Efficient Protocol for Clock Synchronization in WSNs

“Fly-By-Wireless” paradigm based on wireless connectivity in aircraft has the potential to improve efficiency and flexibility, while reducing weight, fuel consumption and maintenance costs. In this paper, first, the opportunities and challenges for wireless technologies in safety-critical avionics context are discussed. Then, the assessment of such technologies versus avionics requirements is provided in order to select the most appropriate one for a wireless aircraft application. As a result, the design of a Wireless Avionics Network based on Ultra WideBand technology is investigated, considering the issues of determinism, reliability and security.

/pdf/fly-by-wireless-for-next-generation-aircraft-challenges-and-3jx01r42fs.pdf

Fly-By-Wireless for next generation aircraft: Challenges and potential solutions

A system, method, and apparatus for a synchronized wireless data concentrator are provided for facilitating a precisely synchronized system of nodes in a wireless sensor network for airborne data systems. The wireless data concentrator contains a plurality of IEEE 802.15.4 radio/micro-processor subsystems, which are connected to a local host microprocessor, which is in turn connected to an aircraft data network. The airplane data network also contains a precision clock source and a plurality of specialized network switches, which have a low-jitter data-path routing capability.

Synchronized wireless data concentrator for airborne wireless sensor networks

Survey on synchronization mechanisms in machine-to-machine systems

Cable-less avionics implementation will clearly improve the efficiency of aircraft while reducing weight and maintenance costs. Therefore, with the technological progress of wireless technologies, an alternative avionic communication architecture based on Ultra WideBand (UWB) technology is proposed to fulfill these new needs. To adapt this wireless technology to safety-critical avionics, first, the tuning process of the MAC layer and the integration of accurate reliability mechanisms to achieve timely and reliable communications are presented. Then, an efficient timing and reliability analysis of such a communication network based on Network Calculus is detailed. This analysis integrates the impact of non-preemptive message transmission, various service policies in end-systems, e.g., First In First Out (FIFO) and Fixed Priority (FP), and transmission errors. Third, this general analysis is illustrated in the case of a realistic avionic application to replace the AFDX backup network with our proposed UWB-based network to support timely and reliable communications.

Design and analysis of UWB-based network for reliable and timely communications in safety-critical avionics

The behavior of Wireless Sensor Networks (WSN) is nowadays widely analyzed. One of the most important issues is related to their energy consumption, as this has a major impact on the network lifetime. Another important application requirement is to ensure data sensing synchronization, which leads to additional energy consumption as a high number of messages is sent and received at each node. Our proposal consists in implementing a combined synchronization protocol based on the IEEE 1588 standard that was designed for wired networks and the PBS (Pairwise Broadcast Synchronization) protocol that was designed for sensor networks, as none of them is able to provide the needed synchronization accuracy for our application on its own. The main goals of our new synchronization protocol are: to ensure the accuracy of local clocks up to a tenth of a microsecond and to provide an important energy saving. Our results obtained using NS-2 (Network Simulator) show that the performance of our solution (IEEE 1588-PBS) matches our application requirements with regard to the synchronization, with a significant improvement in energy saving.

https://hal.archives-ouvertes.fr/hal-00544972/document

An energy-efficient clock synchronization protocol for Wireless Sensor Networks

An Energy-efficient Clock Synchronization Protocol for Wireless Sensor Networks

https://hal.archives-ouvertes.fr/hal-00356854/document

Evaluation of UWB communication for in-flight entertainment system in the aircraft cabin

Structural health monitoring is today growing challenge. A good health structure allows to assure in real-time a good performance level, to keep a high level of safety and to plan maintenance. Why drone applications? Drones are very expansive aircrafts, also referred to as UVA (unmanned air vehicle), exposed to a harsh environment due to their frequent military usage. In this context, propellers are among the key components worth health monitoring. The purpose of our research is to develop for the drone propeller an integrated electronics combining accelerometers and signal processing, able to record damaging events for the drone: shocks, vibrations or overspeeds whereas strain gauges could not analyze all these criteria. These parameters allow concluding whether the blade is damaged or not. This paper will present our embedded microsystem on drone propellers. Then we will show through real experiments how it is possible to monitor and detect events like stone shocks, propeller overspeeds or too strong vibrations. Specific algorithm for diagnosis will be discussed and evaluated in different environment tests conditions. Moreover the use of a wireless synchronization between several propellers will be studied too.

/pdf/embedded-blade-microsystem-and-events-recorder-for-drone-zjxwzknzd4.pdf

Embedded blade microsystem and events recorder for drone structural health monitoring

This paper deals with the embedded network dedicated to the entertainment system of passenger cabin in an aircraft The work described in this paper focuses on a wireless solution to interconnect the main components of this system The selected solution is UWB with smart antennas This solution is proved to be able to provide the system with the needed bandwidth The self-configuration capability of the system is also demonstrated

Roxana Albu

Papers

An energy-efficient clock synchronization protocol for Wireless Sensor Networks

An Energy-efficient Clock Synchronization Protocol for Wireless Sensor Networks

Evaluation of UWB communication for in-flight entertainment system in the aircraft cabin

Embedded blade microsystem and events recorder for drone structural health monitoring

Evaluation of uwb comnunication for ife system in the aircraft cabine