1. Designing An 802.11g Ad-hoc Network for Multimedia Communication Chung-Wei Lee & Jonathan C.L. Liu Presented By: Mahendra Kumar

2. Layout Introduction Wireless network problems Performance of Ad-hoc network in different environment- Result and Analysis Proposed scheme for routing decision- Max throughput Simulation results Conclusion Future work

3. Introduction Ad-hoc mode –54 Mbps theoretical limit Route optimization to support multimedia communication. Has a mixed environment depending upon the path. Is Min-Hop count algorithm okay? Focus should be in maximizing the overall throughput from source to destination.

4. Wireless network problems Ad-hoc operates on 802.11g wireless mode. Has to deal with channel errors due to propagation loss, reflection, interference. Indoor and outdoor environment have different benefits and looses. Indoor- signal has more way to propagate due to reflection. But loss due to scattering and obstacles. Outdoor- signal suffers due to natural obstacles like temperature and humidity. Interference from other sources.

5. Wireless network problems(Contd) Hard to predict how the wireless network will perform under these complex environmental parameters. Routing algorithm for ad-hoc should be adaptive for these different environment. Conventionally, the network bandwidth should be higher with decrease in distance. Experiment and analysis shows that performance is worst within 5 meters distance in indoor. Design a algorithm which takes into all these problems.

6. Two identical laptops with Pentium 4 processor, 512 memory, linksys 802.11g, 2.4 GHz wireless card set in ad-hoc mode. Custom benchmarking tool built on top of the existing TCP/UDP protocol stack. Three different Environment: Indoor without obstruction Outdoor without obstruction Penetrating wall Performance of Ad-hoc network

7. Performance of ad-hoc network Indoor without obstruction: Department basement Three distances: Within 5m, 5m - 10m, 10m – 20m Outdoor without obstruction Parking lot Distances of 5, 10, 15, 20 and 25 meters Penetrating wall One indoor laptop, other laptop outside such that there is a wall between them. Change the distance between them from 5, 10, 15 and 20.

8. Indoor TCP without obstruction Performance increase with distance. Why? larger messages cause smaller software overhead 19% throughput improvement by increasing pkt size from 32KB to 4 MB

9. Indoor UDP without obstruction Performs better than TCP. Why? Less overhead than TCP

10. Outdoor TCP without obstruction Distance trend not similar to the Indoor behavior. Why? Less multi-path interference.

11. Outdoor UDP without obstruction Similar trend as outdoor TCP but improved throughput.

12. Penetrating Wall-TCP Throughput decrease with increase in distance.

13. Proposed Scheme Throughput-distance is the major concern in QoS routing in ad-hoc. Hence routing should be done based on maximum throughput and not on min- hop count. Majority of existing schemes do not take distance and throughput into account.

14. Generating simulating nodes Random topology algorithm

15. Max Throughput algorithm

16. Simulation design parameters Generating n random nodes in an area of 300 by 300 meters using random topology algorithm. Calculate the end to end bandwidth for all possible node pairs. Calculate average bandwidth over all paths. i.e. n(n-1)/2 paths and 100 topologies.

17. Comparing Average Path bandwidth

18. Path bandwidth distribution

19. Conclusion Proposed scheme of max throughput performs better than min hop count. Better suitable for multimedia based traffic. Higher number of nodes gives more average bandwidth between source and destination in max throughput.

20. Future Work Simulation on different operating systems. Routing nodes are mobile in ad-hoc. Some nodes can move to appropriate position to increase the throughput. On the contrary, some may lose their connection. Find a novel scheme which can optimize the position of nodes to guarantee max throughput. Exploring a routing scheme based on combination of Min-hop and Max-throughput and min-distance algorithm.

21. Questions?