Measurement-based Admission Control for multi-hop Wireless Mesh Networks

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

2. Wireless Mesh Networks 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 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 Dhruv Gupta, EEC 273

5. YAO: Yet Another Outline • Problem statement • Related work • Motivation • Methodology • Conclusion 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 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. 363-377, 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 802.11 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 26 - 29, 2006), DIWANS '06 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 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 Dhruv Gupta, EEC 273

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

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

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

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

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

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