1. “Fly-By-Wireless” Chris Dimoulis CS 441 Fall 2013

2.  Aircraft Systems (Current)  Benefits of Wireless System  Characteristics and Obstacles  Proposed Solutions

3.  Cables and Pulleys  Direct connection from flight controls to control surface  Hydraulic  Direct manipulation of hydraulic actuators in flight controls  Fly-By-Wire  Avionics Full Duplex Switched Ethernet (AFDX) used to send data from controls to actuators

4.  View and manipulate flight and engine data\  Old Systems  Pressure systems for altitude and airspeed  Mechanical linkages for engine data (tachometer and manifold pressure)  New Systems  Full Authority Digital Engine Control (FADEC)  Automatically controls engine parameters, sends data to pilots through AFDX

5.  Cost from Weight Reduction  Cable costs: A320: $14MB787: $50M [1]  A380: 300 miles (500 km) of wire [2]  Weight reduction means better fuel efficiency and increased space for revenue weight

6.  Improved Safety and Less Maintenance  Less Wire degradation  U.S. Navy: 78 aircraft made non-mission capable due to wiring, 1000 aborts from wiring faults [2]  Wired interconnects and potential fires ▪ B 747 tank explosion due to arcing between fuel sensor wiring [3]

7.  Real-Time and Deterministic [1]  Aircraft Network must behave in a predictable way  Current system provides 100Mbps  Latencies must be bounded and deadline constraints respected

8.  Reliability and Availability  Probability of failure needs to be 10 -9 per flight hour [1]  Fault Detection  Long lifetime: Avionics system lifetime can be 20 – 30 years [1]

9.  Security [1]  Data confidentiality to prevent passive eavesdropping  Data integrity to guarantee data is not altered in transit  Prevent unauthorized access to network

10.  Electromagnetic Compatibility [1]  Deployment is in a harsh physical environment  Large temperature and humidity changes along with vibrations  Intense radio frequency noise

11. Table reproduced from [1]

12.  802.11n + Adequate Data rate + Uses Point Coordination Function for contention free mode + Reliability: Automatic Retransmission ReQuest (ARQ ) - Not adapted for multicast [1] - High possibility of interference from common devices [1]

13.  ECMA-368 High Rate Ultra WideBand + Adequate Data rate and ranges + Distributed Reservation Protocol  TDMA (Contention free) + More secure from “man-in-middle” than 802.11

14.  Begin with a hybrid system  Full Duplex Ethernet Switch to connect clusters Image reproduced from [1]

15.  MAC Protocol Proposals  Need predictable behavior under real-time constraints ▪ Synchronization protocol for TDMA  Reliability Mechanism for sending/receiving data ▪ Probability of failure to be 10 -9 per flight hour

16.  Synchronization Protocol  IEEE1588 Wired network synchronization have been implemented within few nanoseconds precision  IEEE1558 has reached less than 200 nanosecond precision for wireless network synchronization, however too many messages  Proposed enhanced IEEE1588

17.  Synchronization Protocol  Master/Slave/Passive node  If slave node fails passive node can fill in Image reproduced from [1]

18.  Reliability Mechanism  Need adequate acknowledgement and retransmission mechanism  Communication is multicast ▪ Multiple ACKs colliding? ▪ Overhead from sender needing to receive all ACKs

19.  Reliability Mechanism  Designated “leader” of cluster  ACK from leader, NACK from rest  If sender hears NACK or nothing (due to ACK/NACK collision) then it will retransmit Image reproduced from [1]

20.  ECMA-368 can provide adequate data rate, contention free, and security properties  Needs predictable real-time behavior  Enhanced IEEE1588 synchronization  Reliable data reception  Cluster leaders with ACK/NACK messages

21. [1] D. Dang, A. Mifdaoui,and T. Gayraund, “Fly-By-Wireless for Next Generation Aircraft: Challenges and Potential solutions.” (In Press: 2012) In: Wireless days conference, 21-23 Nov 2012, Dublin, Ireland [2] R. K. Yedavalli, R. K. Belapurkar, “Application of Wireless Sensor Networks to Aircraft Control and Health Management.” Journal of control Theory & Applications. February 2011; 9(1):28. [3] M. Panitz, D. Hope, W. Crowther, et al. “The opportunities and challenges associated with wireless interconnects in aircraft.” Proceedings Of The Institution Of Mechanical Engineers -- Part G -- Journal Of Aerospace Engineering (Sage Publications, Ltd.) [serial online]. April 2010;224(4):459.