1. Advisor: Frank Yeong-Sung Lin, Ph.D. Presented by Yu-Jen Hsieh 謝友仁
A Near-Optimal Distributed QoS Constrained Routing Algorithm for Multichannel Wireless Mesh Networks 多信道無線網狀網路下近似最佳化之 分散式具服務品質限制路由演算法
Advisor: Frank Yeong-Sung Lin, Ph.D.
Presented by Yu-Jen Hsieh 謝友仁

2. Agenda Abstract Problem Description Problem Formulation
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Agenda
Abstract
Problem Description
Problem Formulation
Channel Assignment Heuristic
Routing Metric
Dynamic Routing Protocol
Schedule

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Abstract
For each mesh client, it is desirable to choose the route with low interference and minimum delay to access the Internet; however, this is suboptimal for the whole system.
Channel assignment heuristic algorithm
Distributed QoS constrained routing algorithm
A routing metric which is composed of average cross-network packet delay and end-to-end delay and derived from a Lagrangean Relaxation based problem formulation.
OSPF based protocol for dynamic routing
K shortest paths and K fastest paths

4. Wireless Mesh Networks
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Wireless Mesh Networks

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Problem Description
The problem we addressed is to find out the arc weight form of each link while taking “system perspective” and “user perspective” into account
The environment we considered here is a multichannel WMN which is one case of this generic formulation for illustration purpose
In the multichannel WMN, the link capacity degrades due to the other links using the same channel in the interference range.
every link is assumed to be fairly used
the link capacity is divided by the number of interference links in the following formulation

6. Problem Description 6 Problem Assumptions:
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Problem Description
Problem Assumptions:
The channel assignment for each mesh router is fixed for a long period.
Each mesh router is equipped with multiple a NICs, each of which operates on a particular and non-overlapping channel.
Each mesh router can simultaneously communicate with its neighbors in transmission range without interferences by using different channels for each link.
All mesh routers in the network use the same fixed transmission power and have fixed transmission range and interference range.
A virtual node is added as the destination node to only connect to the mesh access point via wired-line.
All flows are transmitted to this virtual node via the mesh access point.

7. Problem Description 7 Given: Objective: Subject to: To determine:
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Problem Description
Given:
The set of links.
The set of mesh routers.
The link capacity of each link.
The number of interference links of each link.
The traffic requirement for each O-D pair.
Objective:
To minimize the average cross-network packet delay of the WMN.
Subject to:
QoS constraints.
Path constraints.
Capacity constraints.
Flow constraints.
To determine:
The arc weight form of each link which is composed of the link mean delay and the
derivative of queue length for each O-D pair.

8. Notation of Given Parameters
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Notation of Given Parameters

9. Notation of Decision Variables
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Notation of Decision Variables

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Problem Formulation

11. Channel Assignment Heuristic
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Channel Assignment Heuristic

12. Channel Assignment Heuristic
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Channel Assignment Heuristic

13. Channel Assignment Heuristic
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Channel Assignment Heuristic

14. Channel Assignment Heuristic
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Channel Assignment Heuristic

15. Channel Assignment Heuristic
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Channel Assignment Heuristic

16. Channel Assignment Heuristic
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Channel Assignment Heuristic

17. Channel Assignment Heuristic
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Channel Assignment Heuristic

18. Solution Approach for Multichannel WMN Formulation
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Solution Approach for Multichannel WMN Formulation

19. Subproblem 1 (related to decision variable )
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Subproblem 1 (related to decision variable )

20. Subproblem 2 (related to decision variable and )
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Subproblem 2 (related to decision variable and ) 20 20

21. Subproblem 2 (related to decision variable and )
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Subproblem 2 (related to decision variable and )

22. Subproblem 2 (related to decision variable and )
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Subproblem 2 (related to decision variable and ) 22

23. Subproblem 2 (related to decision variable and )
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Subproblem 2 (related to decision variable and ) 23

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Routing Metric 24

25. The Arc Weight of Each Link
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The Arc Weight of Each Link 25

26. Estimation of Routing Metric Parameters
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Estimation of Routing Metric Parameters
Perturbation Analysis
estimate the derivative of queue length
also estimate the value of link mean delay
ECHO packets
Each adjacent link mean delay estimated by the node is a half of the used time corresponding to each neighbor
A monotonically increasing and convex function to approximate the queue length

27. Estimation of Routing Metric Parameters
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Estimation of Routing Metric Parameters

28. Dynamic Routing Protocol
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Dynamic Routing Protocol

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Routing Algorithm
The Dijkstra algorithm computes the only one shortest path for each node pair, to make our routing algorithm be more flexible, we want to construct the second shortest path, the third shortest path, and so on
“K shortest paths”

30. The QoS Satisfaction Heuristic Algorithm
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The QoS Satisfaction Heuristic Algorithm

31. Schedule Estimation of Metrics NS-2 K Shortest Path Channel Assignment
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Schedule
March
April
May
June
July
Estimation of Metrics
NS-2
K Shortest Path
Channel Assignment
QoS Satisfaction
Simulation
Conclusion

32. Thanks for your listening