1. Wireless Mesh Networks: Cross-Layer Scheduling Jason Ernst University of Guelph Prepared for CS6650 – Mobile and Wireless Networks

2. Presentation Outline Introduction & Background – Wireless Mesh Networks Motivation – Fair Scheduling – Classification of Scheduling Techniques – Cross-Layering Related Work Current Problems Future Work & Conclusions Questions 2Jason Ernst - University of Guelph

3. Wireless Mesh Networks WMN - Wireless Mesh Network: – Ad-hoc network with a core which has limited mobility Mesh Router: – A wireless base station with limited or no mobility – Infrastructure of the network Mesh Clients: – A wireless node which is fully mobile, may also act as a router in some WMNs Image: Indigo Systems – WMN for Environmental Monitoring 3Jason Ernst - University of Guelph

4. Motivation: Fair Scheduling Starvation & Unequal Quality of Service (QoS) – “Greedy” flows cause other traffic to be ignored resulting in starving or unequal QoS – Nodes closer to the gateways cause farther nodes starvation or unequal QoS In commercial applications people who pay the same amount expect the same quality of service 4Jason Ernst - University of Guelph

5. Motivation: Fair Scheduling Jason Ernst - University of Guelph5 Image: NC State University Elec. Eng. Dept.

6. Classifications of Scheduling Jason Ernst - University of Guelph6 ThroughputFairness

7. Classifications of Scheduling Jason Ernst - University of Guelph7 ThroughputFairness Maximum Throughput Scheduling Equal Fairness Proportional Fairness Min-Max

8. Motivation: Cross-Layering Still ongoing debate as to whether cross- layering is worthwhile or not – Performance improvement and more intelligent decisions – However possibility of “spaghetti-code” or unintended effects due to unexpected interactions with other layers 8Jason Ernst - University of Guelph

9. Cross-Layering Methods of Cross-Layering -Power Adaption -Adjust Power in order to avoid interference and increase fairness -Routing / MAC [J. Thomas] -Transport / LL [Wang et al.] -Rate Control -Adjust the data rates in order to achieve fairness -Network / Transpot [Neely et al.] -Transport / Network / MAC [Tang et al.] -Route Control -Change routes in order to avoid congestion -LL / network [Kuran et al.] 9Jason Ernst - University of Guelph

10. Related Work: Fair Scheduling Operating Systems – User / process scheduling in interactive OS’s started in the 1960s and 70’s (multics, unix) Wired Networks & Wireless LAN (single hop) Ad-hoc Networks Distributed Computing – SHARCNET Cross-Layering: Wired Networks Jason Ernst - University of Guelph10

11. Current Problems Cross-Layered Fair Scheduling – Some papers make assumptions such as single hop networks, limited mobility, fixed topology (APs cannot be added or removed) – Assumption which treats uplink and downlink together when it may be beneficial to treat them independently – Localized VS Centralized scheduling & load balancing 11Jason Ernst - University of Guelph

12. Future Work Future Work: – Identifying an area of current research to expand upon – Make use of experimentation to determine optimal parameter values, metrics for load balancing etc. – Cross Layered Optimizations on solution – Write a thesis based on the research 12Jason Ernst - University of Guelph

13. References Agrawal et Al. Achieving Load Balancing in Wireless Mesh Networks Through Mulitple Gateways. IEEE. 2006. 807-812. Bejerano, Yigal., Han, S-J., Kumar, Amit. Efficient Load-Balancing Routing for Wireless Mesh Networks. 2007. Computer Networks. 51. 2450-2466. Chandranmenon et. Al. On the Design and Implementation of Infrastructure Mesh Networks. IEEE Workshop on Wireless Mesh Networks (WiMesh) 2005. Cheng, S-M., Lin, Phone., Huang, Di-Wei., Yang, Shun-Ren. A Study on Distributed / Centralized Scheduling for Wireless Mesh Network. 2006. IWCMC ’06. ACM. 599-604. Gupta, Piyush., Sankarasubramaniam, Yogesh., Stolyar, Alexander. Random-Access Scheduling with Service Differentiation in Wireless Networks. 2005. IEEE. 1815-1825. Erwu, Liu., Shan, Jin., Gang, Shen., Luoning, Gui. Fair Scheduling in Wireless Multi-Hop Self- Backhaul Networks. IEEE AICT/ICIW 2006. Hubaux, J-P., Salem, Ben Naouel. A Fair Scheduling for Wireless Mesh Networks. WIMESH. 2005 Koutsonikolas, Dimitrios., M. Das., Saumitra., Hu, Charlie, Y. An Interference-aware Fair Scheduling for Multi-cast in Wireless Mesh Networks. 2008. Journal of Parallel and Distributed Computing. 68. 372-286. Popa, Lucian., Rostamizadeh, Afshin., Karp, Richard, M., Papadimitriou, Christos., Stoica, Ion. Balancing Traffic Load in Wireless Networks with Curveball Routing. 2007. Mobihoc ‘07. ACM. 170 – 179. 13Jason Ernst - University of Guelph

14. References J. Thomas, “Cross-Layer Scheduling and Routing For Unstructured And Quasi-Structured Wireless Networks” M.S. Kuran, G. Gur, T. Tugcu, F. Alagoz, “Cross-Layer Routing-Scheduling in IEEE 802.16 Mesh Networks”, in Mobilware’08. Austria, 2008. M. Neely, R. Urgaonkar, “Cross-layer adaptive control for wireless mesh networks,” in Ad Hoc Networks Vol. 5, pp 719-743, 2007. J. Tang, G. Xue, W. Zhang, “Cross-Layer Design for End-To-End Throughput and Fairness Enhancement in Multi-Channel Wireless Mesh Networks,” in IEEE Transactions on Wireless Communications, Vol. 6. pp 3482-3486. October 2007. X. Wang, K. Kar, “Cross-Layer Rate Control for End-to-End Proportional Fairness in Wireless Networks with Random-Access,” in MobiHoc ’05. Illinois, USA, 2005. J. Tang, G. Xue, C. Chandler, W. Zheng, “Link Scheduling with Power Control for Throughput Enhancement in Multihop Wireless Network V. Kawadia, P.R. Kumar, “A Cautionary Perspective on Cross-Layer Design,” in IEEE Wireless Communications, pp 3-11, February 2005. I.F. Akyildiz, X. Wang, “Cross-Layer Design in Wireless Mesh Networks,” in IEEE Transactions on Vehicular Technology, Vol. 57, 2, pp 1061- 1076, March 2007. 14Jason Ernst - University of Guelph

15. Questions? Jason Ernst jernst@uoguelph.ca University of Guelph Advisor: Dr. Mieso Denko 15Jason Ernst - University of Guelph