1. NTU IM OPLAB Providing survivability against jamming attack for multi-radio multi-channel wireless mesh networks Journal of Network and Computer Applications Author: Shanshan Jiang, Yuan Xue Advisor: Frank,Yeong-Sung Lin Presented by Jia-Ling Pan 1 2010/06/08

2. COMPANY LOGO Outline  Introduction  System model  Routing and channel assignment without jamming attacks  Optimal restoration strategies under jamming attacks 2 2010/06/08

3. COMPANY LOGO Outline  Dynamic channel assignment under jamming attacks  Static channel assignment under jamming attacks  Performance degradation model  Performance evaluation  Concluding remarks 2010/06/08 3

4. COMPANY LOGO Introduction  Wireless mesh network are capable of communicating with each other and cooperating to relay traffic throughout the network via multiple hops.  Built upon open wireless medium, wireless mesh network is particularly vulnerable to jamming attacks.  The ability to deal with jamming attacks and maintain an acceptable level of service degradation in presence of jamming attack is thus a crucial issue. 4 2010/06/08

5. COMPANY LOGO Introduction  When jamming occurs, the traffic going through that jamming area is disrupted.  The network either switches to different channels other than those of the jammers, and/or its traffic needs to be rerouted around the jamming area.  This paper investigates the jamming defense strategies via the joint design of traffic rerouting, channel re-assignment, and scheduling in a multi-radio multi-channel wireless mesh network. 5 2010/06/08

6. COMPANY LOGO Introduction  First formulate the optimal network restoration problem as linear programming problem, which gives an upper bound on the achievable network throughput.  Consider two strategies, namely global restoration and local restoration.  Based on the LP solutions, providing a greedy scheduling algorithm using dynamic channel assignment, which schedules both the network traffic and the jamming traffic. 6 2010/06/08

7. COMPANY LOGO Introduction  Further provide a greedy static edge channel assignment algorithm, where a channel is assigned to an edge at the beginning and will remain fixed over all time slots.  Define two performance degradation indices, transient disruption index (TDI) and throughput degradation index (THI). 7 2010/06/08

8. COMPANY LOGO Outline II ntroduction SS ystem model RR outing and channel assignment without jamming attacks OO ptimal restoration strategies under jamming attacks 8 2010/06/08

9. COMPANY LOGO System model  Normal node model Consider a multi-radio multi-channel wireless mesh network and model it as a directed graph G=(V,E,C). Each node v is equipped with k(v) radios. E=E T υ E I All nodes have a uniform transmission range (R T ) and a uniform interference range (R I ). A transmission edge e=(v,v’) Є E T is formed if r(v,v’) ≤ R T. An interference edge e=(v,v’) Є E I is formed if R T ≤ r(v,v’) ≤ R I. 9 2010/06/08

10. COMPANY LOGO System model Wireless channel capacity is the same for all edge using channel c (Φ c ). Packet transmission from node v to v’ is successful if and only if ： There is a transmission edge e=(v,v’) Є E T. Node v and v’ have radios that support a common channel c. Any other node v” Є V within the interference range of the sending node v or the receiving node v’, i.e., e=(v,v”) Є E T υ E I or e=(v’,v”) Є E T υ E I, is not transmitting on channel c. 10 2010/06/08

11. COMPANY LOGO System model I(e) ： Interference set which contains the transmission edges that interfere with transmission edge e, e Є E T. The traffic between any pair of nodes as a flow and denote it as f Є F. s f ： the sending node of flow f r f ： the receiving node of flow f d f ： the demand of flow f The traffic of flow f will be routed over multiple paths and multiple channels ： x f (e,c) ： The amount of flow f’ s traffic being routed on edge e over channel c. 11 2010/06/08

12. COMPANY LOGO System model ∑ f Є F x f (e,c) ： The amount of all flows’ traffic on edge e over channel c  Jamming node model j c Є J c ： A wireless jammer node at channel c. J c ： The set of all the jammers detected at channel c. J ： The set of all the jammers over all the channels. G jc ： Constant traffic generating rate 0 ≤ G jc ≤ Φ c. All the jamming nodes have a uniform jamming range R J. 12 2010/06/08

13. COMPANY LOGO System model Assume that they are smart jammers that can totally occupy the channels when sending jamming traffic. J c (e),e Є E T υE I ： the set of jammers who have one or both of the two end nodes of the edge e within its jamming range. E T (j c ) ： the set of transmission edges whose sending or receiving node is within the jamming range of j c. Assume that two jammers are not within the jamming range of each other. 13 2010/06/08

14. COMPANY LOGO Outline II ntroduction SS ystem model RR outing and channel assignment without jamming attacks OO ptimal restoration strategies under jamming attacks 14 2010/06/08

15. COMPANY LOGO Routing and channel assignment without jamming attacks  First study the routing and channel assignment problem in a multi-radio multi-channel wireless mesh network when there is no jamming node.  The goal is achieving the maximum throughput.  Find a best strategy that can minimize the performance degradation to defend against jamming attacks. 15 2010/06/08

16. COMPANY LOGO Routing and channel assignment without jamming attacks  Under this network and traffic model, optimizing the performance of a wireless mesh network via the joint design of routing, channel assignment, and scheduling can be formulated as an integer linear programming problem (ILP).  To make the integer linear programming problem tractable, existing approaches (Alicherry et al., 2005; Kodialam and Nandagopal, 2005; Kumar et al., 2005) usually solve its LP relaxation and then scale the solution to achieve feasibility. 16 2010/06/08

17. COMPANY LOGO Routing and channel assignment without jamming attacks  The necessary conditions of channel assignment and scheduling for a multi- radio multi-channel wireless network are summarized as follows:  Node radio constraint ：  Channel congestion constraint ： 17 2010/06/08

18. COMPANY LOGO Routing and channel assignment without jamming attacks  Minimum flow throughput scaling factor(λ) ： Characterizes the throughput of a given routing with respect to a certain traffic demand. 18 2010/06/08

19. COMPANY LOGO Routing and channel assignment without jamming attacks flow conservation constraint node radio constraint channel congestion constraint 19 2010/06/08

20. COMPANY LOGO Outline II ntroduction SS ystem model RR outing and channel assignment without jamming attacks OO ptimal restoration strategies under jamming attacks 20 2010/06/08

21. COMPANY LOGO Optimal restoration strategies under jamming attacks  The disrupted network traffic can be rerouted to use other intermittent nodes away from the jamming area, or switched to another channel instead of using the jammed channel.  Include the jamming traffic into the channel congestion constraint: 21 2010/06/08

22. COMPANY LOGO Optimal restoration strategies under jamming attacks globallocal  The network restoration via joint traffic rerouting and channel re-assignment under global and local restoration strategies. 22 2010/06/08

23. COMPANY LOGO Optimal restoration strategies under jamming attacks  Global restoration flow conservation constraint node radio constraint channel congestion constraint 23 2010/06/08

24. COMPANY LOGO Optimal restoration strategies under jamming attacks  Local restoration Need to find the bypass flows that need to be partially routed away from the jamming area. For these flows, their immediate upstream and downstream nodes surrounding the jamming area should remain unchanged. 24 2010/06/08

25. COMPANY LOGO Optimal restoration strategies under jamming attacks Bypass flows For a jamming node j c and a flow f ： in f (j c ) ： The set of nodes that are within the jamming area of j c. pre f (j c ) ： The set of nodes sending data of f directly to one or more nodes in in f (j c ). post f (j c ) ： The set of nodes receiving data of f directly from one or more nodes in in f (j c ). 25 2010/06/08

26. COMPANY LOGO Optimal restoration strategies under jamming attacks 26 2010/06/08

27. COMPANY LOGO Optimal restoration strategies under jamming attacks Optimal bypass restoration X bf (v,v’,jc) (e,c) ： The traffic demand of b f (v,v’,j c ) that is routed over edge e and channel c. The bypass flows need to share the wireless channel capacity with the original flows, both of them need to be scaled again. λ b ： Scaling factor with bypass restoration. 27 2010/06/08

28. COMPANY LOGO Optimal restoration strategies under jamming attacks node radio constraint channel congestion constraint 28 2010/06/08

29. COMPANY LOGO Optimal restoration strategies under jamming attacks bypass flow conservation constraint 29 2010/06/08

30. COMPANY LOGO Outline DD ynamic channel assignment under jamming attacks SS tatic channel assignment under jamming attacks PP erformance degradation model PP erformance evaluation CC oncluding remarks 30 2010/06/08

31. COMPANY LOGO Dynamic channel assignment under jamming attacks  The global restoration and the local restoration give an upper bound on the achievable network throughput.  Dynamic channel assignment problem ： A radio may need to switch to a different channel at different time slots. Provides the maximum flexibility in channel assignment and scheduling. Greedy approach 31 2010/06/08

32. COMPANY LOGO Dynamic channel assignment under jamming attacks  Schedule both the network traffic on the edges and the jamming traffic.  I(e * ) ： The set of transmission edges that interfere with edge e *.  E(J c * ) ： The set of transmission edges that are within the jamming range of jammer j c *. 32 2010/06/08

33. COMPANY LOGO Dynamic channel assignment under jamming attacks 33 2010/06/08

34. COMPANY LOGO Dynamic channel assignment under jamming attacks 34 2010/06/08

35. COMPANY LOGO Dynamic channel assignment under jamming attacks round0123456 e* e1e1 e2e2 e2e2 e1e1 e2e2 e1e1 x (e 1,c) 3222110 x (e 2,c) 3321100 35 V V’ V’’ (e 1,c) (e 2,c) node set v1,1,2,2,3,31,1,2,2,3,3,….. v’1,2,31,1,2,2,3,3,…… v’’1,2,31,1,2,2,3,3,…… edge- channel set e 1,c1,2,31,2,3,4,……. e 2,c1,2,31,2,3,4,……. k(v)=k(v’)=k(v’’)=2 color poorcolor set 2010/06/08

36. COMPANY LOGO Dynamic channel assignment under jamming attacks  N ： The maximum number of time slots taken by all the edge-channel pairs.  The new scaling factor λ S J after scheduling is calculated as ： 36 2010/06/08

37. COMPANY LOGO Outline DD ynamic channel assignment under jamming attacks SS tatic channel assignment under jamming attacks PP erformance degradation model PP erformance evaluation CC oncluding remarks 37 2010/06/08

38. COMPANY LOGO Static channel assignment under jamming attacks  Dynamic channel assignment provides the maximum flexibility, but results in channel switching overhead.  Static edge channel assignment problem A channel is assigned to an edge at the beginning and will remain fixed over all time slots. Greedy approach 38 2010/06/08

39. COMPANY LOGO Static channel assignment under jamming attacks  Constraint set The node radio constraint and the channel congestion constraint have a common structure. L Left sides of (1)&(10),have L sets, each of which is composed of (edge, channel)pairs. L Right sides of (1)&(10), have L fixed values, where L is the number of all the expanded inequalities. 39 2010/06/08

40. COMPANY LOGO Static channel assignment under jamming attacks S 1, S 2,…., S L ： the sets of (edge, channel) pairs. β S 1 -G S 1, β S 2 -G S 2,…., β S L -G S L ： their corresponding values. If S i comes from the node radio constraint ： β S i = k(v)Φ c, G S i = 0. If S i comes from the channel congestion constraint ： β S i = Φ c, G S i = ∑ j c Є J c (e) G j c. General form of Inequality (1) & (10) using constraint sets is defined as follows: 40 2010/06/08

41. COMPANY LOGO Static channel assignment under jamming attacks  Static channel assignment x(e) ： The amount of all flows’ traffic over all the channels on edge e. For simplicity, assume that only one channel can be assigned to a given edge. one particular Therefore, x(e) is assigned to one particular channel assigned to edge e. The basic idea of static channel assignment algorithm is to distribute the load on the constraint sets as much as possible among the given channels. 41 2010/06/08

42. COMPANY LOGO Static channel assignment under jamming attacks 42 2010/06/08

43. COMPANY LOGO Outline DD ynamic channel assignment under jamming attacks SS tatic channel assignment under jamming attacks PP erformance degradation model PP erformance evaluation CC oncluding remarks 43 2010/06/08

44. COMPANY LOGO Performance degradation model  Challenge for choosing the restoration strategy ： Understand the tradeoff between the overhead involved in repairing the failed traffic path(s) and the traffic throughput and network congestion after restoration.  Transient Disruption Index (TDI) Based on the repair overhead for the failed traffic path(s) during restoration.  Throughput Degradation Index (THI) Characterizes throughput degradation of the new network after restoration. 44 2010/06/08

45. COMPANY LOGO Performance degradation model  Transient disruption index (TDI) Use the number of modified routing table entries as an estimate of the repair overhead for the failed path(s). For local repair, only the boundary nodes outside the jamming area will try to find the alternative paths. For global repair, the source node initiates a new route discovery and involves more routing table entry modifications. 45 2010/06/08

46. COMPANY LOGO Performance degradation model r v (c,v’) ： A routing table entry of node v’s routing table. At a given channel c, it is calculated as the ratio of the total traffic of all the flows sending from node v to its next-hop node v’ to the total traffic of all the flows receiving at node v. r v * ( c,v’) ： Its corresponding routing table entry for the new network under jamming. r(G) ： All the routing table entries of the nodes in the network G. 46 2010/06/08

47. COMPANY LOGO Performance degradation model  Throughput degradation index (THI) Use the changes of the minimum flow throughput scaling factor λ as an estimate of the throughput degradation of the new network. For local repair, it achieves partially optimal utilization of the network. For global repair, all flows in the network will be considered in order to get an optimal utilization of the network. 47 2010/06/08

48. COMPANY LOGO Outline DD ynamic channel assignment under jamming attacks SS tatic channel assignment under jamming attacks PP erformance degradation model PP erformance evaluation CC oncluding remarks 48 2010/06/08

49. COMPANY LOGO Performance evaluation SSSSimulation setup SS imulation result overview CC omparison of TDI and THI under various scenarios CC omparison of λ under various scenarios 49 2010/06/08

50. COMPANY LOGO Performance evaluation 54 wireless nodes are randomly deployed over a 1800*1080 m 2 region. R T = 250 m, R I = 250 m. Channel capacity Φ c (c Є C) is set as 1 Mbps. Three randomly distributed jamming nodes. R J = 100 or 200 m. Traffic generating rates of the jammers are from 0.2 to 0.8 Mbps. 50 2010/06/08

51. COMPANY LOGO Performance evaluation All the flows‘ traffic demand of 1 Mbps. 51 2010/06/08

52. COMPANY LOGO Performance evaluation  Evaluate the performance of the global restoration and local restoration under two scenarios: Single channel All the network nodes and jamming nodes use the same channel. Multiple channels All the network nodes and jamming nodes use multiple channels and │ C │ =5. Each network node is equipped with multiple radios. Jammers are able to send jamming traffic over all the channels. 52 2010/06/08

53. COMPANY LOGO Performance evaluation SS imulation setup SSSSimulation result overview CC omparison of TDI and THI under various scenarios CC omparison of λ under various scenarios 53 2010/06/08

54. COMPANY LOGO Performance evaluation 54 2010/06/08

55. COMPANY LOGO Performance evaluation 55 2010/06/08

56. COMPANY LOGO Performance evaluation 56 2010/06/08

57. COMPANY LOGO Performance evaluation 57 2010/06/08

58. COMPANY LOGO Performance evaluation 58 2010/06/08

59. COMPANY LOGO Performance evaluation SS imulation setup SS imulation result overview CCCComparison of TDI and THI under various scenarios CC omparison of λ under various scenarios 59 2010/06/08

60. COMPANY LOGO Performance evaluation 60 2010/06/08

61. COMPANY LOGO Performance evaluation 61 2010/06/08

62. COMPANY LOGO Performance evaluation SS imulation setup SS imulation result overview CC omparison of TDI and THI under various scenarios CCCComparison of λ under various scenarios 62 2010/06/08

63. COMPANY LOGO Performance evaluation 63 2010/06/08

64. COMPANY LOGO Performance evaluation 64 2010/06/08

65. COMPANY LOGO Outline DD ynamic channel assignment under jamming attacks SS tatic channel assignment under jamming attacks PP erformance degradation model PP erformance evaluation CC oncluding remarks 65 2010/06/08

66. COMPANY LOGO Concluding remarks  This paper investigates the network restoration problem in multi-radio multi- channel wireless mesh networks under jamming attacks.  The defense strategy dynamically adjusts the channel assignment and traffic routes to bypass the jamming area.  Two restoration strategies Global restoration Local restoration 66 2010/06/08

67. COMPANY LOGO Concluding remarks  The goal is to minimize the performance degradation caused by the jamming attack.  Formulates as linear programming problems.  Network performance are evaluated via comprehensive simulation study under different jamming attack scenarios. 67 2010/06/08

68. COMPANY LOGO Concluding remarks  Static channel assignment Inefficient use of radio resource also hinders the network performance improvement when the number of radios is increased.  The post-restoration network performance (i.e., THI) may improve, when the network nodes are equipped with more radios, the disruption during the restoration (i.e., TDI) may get worse, as more radios need to switch channels. 68 2010/06/08

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