1. Dhruv Gupta EEC 273 class project Prof. Chen-Nee Chuah
Measurement-based Admission Control for multi-hop Wireless Mesh Networks
Dhruv Gupta
EEC 273 class project
Prof. Chen-Nee Chuah

2. Wireless Mesh Networks
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Dhruv Gupta, EEC 273

3. Admission Control
Is the simple practice of discriminating which traffic is admitted into a network
The network judges whether it has enough resources available to accept a new connection based on the current network status
Used to control the amount of traffic in the network and thus provide guaranteed service to end users
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Dhruv Gupta, EEC 273

4. Background WMN’s have become increasingly prevalent
Roofnet, SF, Mountain View, Philadelphia and many others
Ease of deployment, increased coverage area and reduced cost have driven the deployment of WMNs
At the same time, low bandwidth, interference and high loss rates are some of the problems
Network management is of crucial importance to provide guaranteed service to end users
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Dhruv Gupta, EEC 273

5. YAO: Yet Another Outline
Problem statement
Related work
Motivation
Methodology
Conclusion
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Dhruv Gupta, EEC 273

6. Problem Definition I/P : Connectivity graph & measurement data
Objective : Perform an AC decision for a given client request by finding a path P from source to destination that satisfies the following constraints
Constraints : For each link ‘i’ on path P, we have
Buser <= α * ABi
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Dhruv Gupta, EEC 273

7. Related work
Yaling Yang, Robin Kravets, "Contention-Aware Admission Control for Ad Hoc Networks," IEEE Transactions on Mobile Computing ,vol. 04, no. 4,  pp , July/August, 2005.
Luo, L., Gruteser, M., Liu, H., Raychaudhuri, D., Huang, K., and Chen, S. 2006, “A QoS routing and admission control scheme for ad hoc networks,” In Proceedings of the 2006 Workshop on Dependability Issues in Wireless Ad Hoc Networks and Sensor Networks (Los Angeles, CA, USA, September , 2006), DIWANS '06
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Dhruv Gupta, EEC 273

8. Motivation Most schemes focus on wireless LANs or Adhoc networks
Simulation based studies do not capture the underlying interference models accurately
No experimental measurement based work yet for wireless mesh networks
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Dhruv Gupta, EEC 273

9. Assumption Small scale WMNs with single gateway node
Single channel for wireless backhaul and separate channels for clients
All traffic directed for the internet – no peer to peer communication within the network
Client based admission control, not flow-based
User resource requirements are assumed to be known
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Dhruv Gupta, EEC 273

10. Problem components… Connectivity graph Network measurements
Centralized admission control algorithm
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Dhruv Gupta, EEC 273

11. Network Discovery Purpose: Constraint:
Advertise node existence/nonexistence
Construct connectivity graph
Constraint:
Achieve node advertisement with minimum resource usage
Accurate record of neighboring nodes
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Dhruv Gupta, EEC 273

12. Hello Message - Types Add - new node being added
Delete - node presumed dead
Update - “I’m alive”
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Dhruv Gupta, EEC 273

13. Network measurement Why? What?
Centralized controller needs an updated view of the network topology statistics
What?
Bandwidth of the links in the network (asymmetric)
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Dhruv Gupta, EEC 273

14. How to get Link Bandwidth?
A wireless link is different from a wired link
Wireless is a broadcast medium, which means traffic on one link will affect bandwidth on another
What is the base variable for bandwidth?
Amount of Data/Time
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Dhruv Gupta, EEC 273

15. Time = Channel Utilization
Channel Utilization is used instead of node utilization because CU is the limiting factor (and is affected by other APs)
We define channel busy time as the total time a node is busy transmitting, receiving or sensing packets
Channel utilization = CBT / tmeasurement
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Dhruv Gupta, EEC 273

16. Amount of Data = Modulation Rate
The maximum bandwidth allowed per link (src to dest) varies based on signal quality and packet loss rate
General upper bound for amount of data that can be sent to a certain neighbor
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Dhruv Gupta, EEC 273

17. Thus,
Upper bound bandwidth to a neighbor = Modulation Rate * (1 - Channel Utilization)
Monitored data is periodically sent to the central controller
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Dhruv Gupta, EEC 273

18. The final piece Central Controller
Implements the admission control algorithm
Takes as input:
Connectivity graph
Available Bandwidth
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Dhruv Gupta, EEC 273

19. Path search algorithm
Use a uniform cost search algorithm to search for a path
From source node, sort the links in decreasing order of available bandwidths
Check if first link satisfies the user requirement
If not, then request cannot be accepted
Else repeat the procedure for subsequent links
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Dhruv Gupta, EEC 273

20. Centralized Admission Control
Client associates to an AP (Wi-Fi assoc req)
AP will send a client association request to centralized controller
Centralized controller will reply (after running admission control algorithm) with a client association reply
AP will receive the reply and send a Wi-Fi assoc reply back to the client
If a path is found, send back association reply and setup route
If no path is found, send back a reply denying the new request
If a new client is accepted or a client leaves the network, the measurements will reflect the same
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Dhruv Gupta, EEC 273

21. Implemented the network discovery protocol
Implemented the central controller algorithm
Currently working on estimation of available bandwidth
Integrate and test the scheme
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Dhruv Gupta, EEC 273

22. Hope you all get A’s and I get an A+
Thank You
Hope you all get A’s and I get an A+
Q & A
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Dhruv Gupta, EEC 273