1. Nash equilibrium for Proactive Anti-jamming in IEEE 802.15.4e
SPEAKER: CHEN-YU TSENG ADVISOR: DR. HO-TING WU /12/01

2. Outline -Introduction -TSCH -Jamming techniques -Metrics
-MAS ( Multi-Agent System)
-Nash equilibrium
-Nash equilibrium model
-TIME-SLOTTED CHANNEL HOPPING – GAME

3. Introduction
-On the railway when the leading train is traveling too fast, and take a long time to stop, for safety reason we're too pessimistic lowering the utilization of the track.
-Virtual coupling:wireless communication link between the trains to ensure that if the leading train starts to break, the following train will do the same and maintain the required safe separation as the two trains while slowing down together.

4. Introduction (cont.)
-For this reason, it should require a safety network with reliability, low packet delay, and protection from interference and jamming.
-IEEE e TSCH:inprove reliability and latency.
-MAS ( Multi-Agent System) & Nash equilibrium :estimate the probability of channel jamming and use game theory to decide whether to hop to a new channel or to not hop.

5. TSCH -Time slot -ASN(Absolute sequence number) ASN 1 2 3 4 5 6 7 8 TS1 2 3 4 5 6 7 8 TS
C→B
B→A
slot offset
Slotframe length

6. Channel
-Channal offset
-HSL(Hopping sequence list)

7. Jamming techniques
-Jamming makes use of intentional radio interferences to attack wireless communication by sending noisy signals on communication channels and keep the medium busy.
-Proactive jammer:send jamming signals on the channel it is operating on. (on one channel only)
-Reactive jammer:jamming only when they observe network activity in a certain channel. (depent on the channel is in used)
-Jamming can be detect by PDR (packet delivery ratio).

8. Metrics
-CWM(channel weighting matrix):assign weight to avliable channels.
-PDR(Packet Delivery Ratio):ratio between the number of acknowledgments received and the number of packets sent.
-BER(Bit Error Ratio):ratio value based on the number of received bits and the number of corrupted bits.
-ETX(Expected Transmission Count): greedy approach to estimate the number of required transmissions needed before the neighbor correctly receives data.

10. ETX(Expected Transmission Count)
- always a value between 1 and λ , and any value above λ will simply be ignored.
-λ can be set in configuration or change while needed. 4

12. MAS ( Multi-Agent System)
-Agent:anything that can perceive its environment through sensors and react.
-Multi-Agent System: network of agents that interact to solve problems that are beyond the individual capacities or knowledge of each agent.
regard every train as an agent using the inputs to take the best desions.

13. Multi-Agent Based System
-MAS on V2Vdir(vehicle to vehicle direct) communicate by IEEE e.
-The goal of each agent is to reach a reliable communication channel through adequate hopping or not hopping decisions.
- Each node has only one radio to communicate data which is considered to be always on.
-keep Train 1 and Train 2 from jammers and interference by partially violating the usual random hopping.
Reactive
Jamming
Train 1
Train 2

16. Nash equilibrium
-A solution to pridict how non-cooperative game should be played.
-Every finity non-cooperative game have a equilibrium point.
-no unilateral deviation in strategy by any single player is profitable for that player.
i: players
S:set of the strategies
si:the strategy player i chose
s-i*:all strategies other players chose except i Pi:payoff of the situation

17. Nash equilibrium in Prisoner's dilemma
prisoner 2 confess
prisoner 2 deny
prisoner 1 confess
-3,-3
0,-5
prisoner 1 deny
-5 ,0
-2,-2

18. Nash equilibrium model
-In design Train 1 and Train 2 will achieve NE only when they settle in the best channe .
α: probability of hopping to a better channel β: probability of losing channel capacity
γ: probability of hopping to a better channel in random

21. TIME-SLOTTED CHANNEL HOPPING – GAME
-assume:
ε=0.50 γ <1 and λ =10.
Note that channel 2 is already occupied by Train1 and Train2 with PDR=2/4=0.50

24. Conclusion
-investigated strategies that attain cooperation in Time-Slotted Channel-Hopping without central coordination or offline scheduling.
-developed an analytical model based on Multi Agents and a zero-sum game model, formulated hopping or not-hopping problem for maximizing channel reliability and system safety by putting nodes under Nash equilibrium.
!!-question of myself:
when does the calculating of ETX and α “really” should execute ?

25. Reference
-Nash equilibrium for proactive anti-jamming in IEEE e (Emerging wireless sensor actuator technologies for I4.0)
Aydin Homay-Mario Sousa-Luis Almeida IEEE 15th International Conference on Industrial Informatics (INDIN)