Static Channel Assignment and Routing in Multi-Radio Wireless Mesh Networks Neil Tang 3/9/2009

1. Static Channel Assignment and Routing in Multi-Radio Wireless Mesh NetworksNeil Tang3/9/2009 CS541 Advanced Networking

2. Outline • References • End-to-End Bandwidth • Problem Definition • Channel Assignment Algorithm • Bandwidth Aware Routing Algorithms • Simulation Results • Conclusions CS541 Advanced Networking

3. References Tang-MobiHoc’2005: J. Tang, G. Xue and W. Zhang, Interference-aware topology control and QoS routing in multi-channel wireless mesh networks, ACM International Symposium on Mobile Ad Hoc Networking and Computing (MobiHoc), 2005 (Acceptance Ratio:14%, Cited by 105 according to Google Scholar), pp. 68-77. CS541 Advanced Networking

4. Wireless Mesh Networks (WMNs) Internet Mesh Router/Gateway Mesh Router Mesh Router Mesh Router/Gateway Wireless Mesh Backbone Mesh Router Mesh Router/Gateway Mesh Router/Gateway Cellular Network WLAN Wireless Sensor Network Mesh Client CS541 Advanced Networking

5. End-to-End Bandwidth • Instance: Link CAP = 1Mbps, single channel and single radio • Connection 1 (A,D) • Connection 2 (E,G) 1/3Mbps 1/3Mbps F D B 1/3Mbps Wireless Mesh Backbone G 1/3Mbps 1/3Mbps C E A CS541 Advanced Networking

6. End-to-End Bandwidth • Instance: Link CAP = 1Mbps, single channel and single radio • Connection 1 (A,D) • Connection 2 (E,G) 0.5Mbps 1Mbps 0.5Mbps F D B Wireless Mesh Backbone 0.5Mbps G 1Mbps C E A CS541 Advanced Networking

7. End-to-End Bandwidth • Instance: Link CAP = 1Mbps, 3 channels {1,2,3} and 2 radios • Connection 1 (A,D) • Connection 2 (E,G) 1Mbps 1Mbps F D B 1Mbps Wireless Mesh Backbone G 2 3 1Mbps 1Mbps C E A 1 CS541 Advanced Networking

8. Assumptions • A stationary wireless mesh backbone network • Multiple radios in each node and multiple channels • The same fixed transmission power • Half-duplex and unicast communications • Static channel assignment • MAC layer: 802.11 DCF and scheduling-based CS541 Advanced Networking

9. Connectivity Graph G(V,E) D F B G A C E CS541 Advanced Networking

10. Network Topology (Communication Graph) Network topology GA (V,EA) determined by a channel assignment A {1,3} {2, 3} 3 D F {1, 3} 3 B 3 (B,D;3) 1 2 3 G {1,3} 1 3 (A,C;2) 2 A C E 2 1 {1,2} {2,3} {1,2} (A,C;1) CS541 Advanced Networking

11. Link/Topology Interference Network topology GA (V,EA) determined by a channel assignment A {1,3} {2,3} 3,5 D F {1,3} 3,4 B 3,5 1,1 2,3 3,5 G {1,3} 1,2 3,4 2,3 A C E 2,3 1,2 {1,2} {2,3} {1,2} Link Interference: e.g., I(B,D;3) = 4 Topology Interference: e.g., I(GA) = 5 CS541 Advanced Networking

12. Channel Assignment Problem Input: a network G and an integer K minimum INterference Survivable Topology Control (INSTC) problem: seeks a channel assignment A s.t. its corresponding network topology GA is K-connected and has the minimum topology interference. CS541 Advanced Networking

13. QoS Routing Problem QoS Routing Problem: seeks a source to destination route and a channel assignment s.t. the end-to-end bandwidth requirement is satisfied. • Connection 1 (A,D,0.5Mbps) F D B Wireless Mesh Backbone G C E A CS541 Advanced Networking

14. Bandwidth-Aware Routing (BAR) Problem Link Load L(e) Link Available Bandwidth A(e) = CAP(e) - ∑e’IEeL(e’) Input: a network topology GA, ρ(s, t, B) Bandwidth-Aware Routing (BAR)problem: seeks a flow allocation F, s.t. the total s-t flow is B and that ∑e’IEef(e’,ρ) ≤ A(e), for e  GA. Remark: IEe – the set of links interfering with link e. f(e’,ρ) – the flow added to link e’ for establishing ρ. CS541 Advanced Networking

15. A Complete QoS Routing Solution Static Channel Assignment Algorithm BAR Algorithm Network Topology Feasible solution? Output the solution and update Block the request Y N End CS541 Advanced Networking

16. Link Potential Interference (LPI) Channel Assignment Algorithm 9 D F 8 7 B 9 8 G 6 7 8 9 A C E CS541 Advanced Networking

17. Channel Assignment Algorithm Binary search to find Imin and k-connected G’(V,E’), s.t. LPI(e)  Imin, eE’ Assign the “least” used channel to the link in G’ one by one based on 4 rules All Radios assigned? Assign nodes having unassigned radios with the “least” used channels N Y End Theorem. The algorithm correctly computes a channel assignment whose corresponding network topology is K-connected in O(Kn3 logm + m2) time CS541 Advanced Networking

18. Channel Assignment Algorithm (Example) {1,3} {1,3} 3 D F {2,3} 3 1 3 B 1 1 G {2,3} 3 2 Instance: Q=2, Channel = {1,2,3}, K=2 2 2 1 A C E 2 {2,3} {1,2} {1,2} Topology Interference I(GA) = 4 CS541 Advanced Networking

19. {1,3} {1,3} Auxiliary Graph Construction 3 D F {2,3} 3 1 3 B 1 1 G {2,3} 3 2 2 2 1 A C E 2 {2,3} {1,2} {1,2} C1 E1 C2 E2 CS541 Advanced Networking

20. Auxiliary Graph Construction D3 F3 B2 B3 D1 F1 G A2 A3 C1 E1 C2 E2 CS541 Advanced Networking

21. BAR LP Minimize Interference Impact: Flow Conservation: Bandwidth Requirement: Interference: Variables: CS541 Advanced Networking

22. Construct GA’ Solve the BAR LP BAR Algorithm Feasible solution? Output the solution and update Block the request Y N End Theorem. The algorithm correctly solves the BAR problem in polynomial time. Weakness? CS541 Advanced Networking

23. Bottleneck Capacity The Link Bottleneck Capacityof link e, denoted by BC(e) is BC(e) = mine∈IEeA(e)/B. The Path Bottleneck Capacityof a single path P, denoted by BC(P), is BC(P) = mine∈PBC(e). CS541 Advanced Networking

24. Maximum Bottleneck Capacity Path (MBCP) Heuristic (Single Path) CS541 Advanced Networking

25. Maximum Bottleneck Capacity Path (MBCP) Heuristic (Single Path) CS541 Advanced Networking

26. QoS Routing (n = 25, C = 3, Q = 2, c = 10.9) (n = 40, C = 3, Q = 2, c = 10.9) CS541 Advanced Networking

27. QoS Routing (n = 40, C = 12, Q = 2, c = 53.9) (n = 40, C = 12, Q = 3, c = 53.9) CS541 Advanced Networking

28. Conclusions • Simulation results show that compared with the CSP scheme, the BAR scheme improves the system performance by 57% on average. CS541 Advanced Networking