1. MobiQuitous 2004Kimaya Sanzgiri Leveraging Mobility to Improve Quality of Service in Mobile Networks Kimaya Sanzgiri and Elizabeth Belding-Royer Department of Computer Science University of California, Santa Barbara

2. MobiQuitous 2004Kimaya Sanzgiri Introduction Current Trends Popularity of multimedia applications Popularity of mobile networking Support for multimedia content on mobile devices Need for support of multimedia applications in mobile networks Resource availability and QoS

3. MobiQuitous 2004Kimaya Sanzgiri Introduction Providing QoS support in mobile networks is difficult Shared medium access Resource availability influenced by neighbors Mobility and dynamic topology Neighborhood may change continuously

4. MobiQuitous 2004Kimaya Sanzgiri Introduction Several previously proposed QoS solutions Basic idea Get QoS requirements from application Query network to see whether satisfactory path is available at user’s current location If yes, make path available to application If no, application is denied route Approach similar to wired networks

5. MobiQuitous 2004Kimaya Sanzgiri Motivation Mobile networks have special characteristics Flexible connectivity Resource availability influenced by neighbors Mobility Can these be leveraged to improve quality of service?

6. MobiQuitous 2004Kimaya Sanzgiri Observation Cellular networks have poor connectivity in some areas Users wander around observing signal strength bars on display Change of location often improves connectivity

7. MobiQuitous 2004Kimaya Sanzgiri Example from Cellular Networks User Base Station I can’t hear clearly… the signal is poor! Maybe I should change my location… User Can you hear me now? User Can you hear me now? User Aha! The signal is great here!

8. MobiQuitous 2004Kimaya Sanzgiri Extending the Idea Lets apply the same idea to multihop mobile networks…

9. MobiQuitous 2004Kimaya Sanzgiri Changing Location in a Multihop Mobile Network I want to see a movie… Network says: You don’t have enough bandwidth Maybe I should change my location… Aha!

10. MobiQuitous 2004Kimaya Sanzgiri Extending the Idea Further Build intelligence into network Network automatically guides user to new location Let us revisit our example…

11. MobiQuitous 2004Kimaya Sanzgiri Network-Suggested Location Change I want to see a movie… Network says: You can’t watch the movie in your current location, but you can if you move to location (x,y) Aha!

12. MobiQuitous 2004Kimaya Sanzgiri Proposed Idea Leverage user mobility to improve service Network suggests new location Beneficial to user Improved quality of service Beneficial to network Spatial re-distribution of users Efficient medium usage

13. MobiQuitous 2004Kimaya Sanzgiri Application Scenarios Applicable to networks with low to moderate mobility Students on a campus Users at a conference Geography researchers in the field Not necessarily applicable to all ad hoc networks Cars on a freeway

14. MobiQuitous 2004Kimaya Sanzgiri Implementation QoS-Aware AODV used as base QoS routing protocol Extended to leverage mobility Note that: Idea is independent of routing mechanism Other QoS protocols can be similarly extended

15. MobiQuitous 2004Kimaya Sanzgiri QoS-Aware AODV (Q-AODV) RREQ specifies resource requirements Intermediate nodes check whether sufficient resources are available If yes, forward the RREQ If no, drop the RREQ Only destination may reply RREP specifies resource availability

16. MobiQuitous 2004Kimaya Sanzgiri Q-AODV Example R TP V QSD RREQ RREP

17. MobiQuitous 2004Kimaya Sanzgiri Mobility-Enhanced Q-AODV (MQ-AODV) Extends Q-AODV to leverage mobility RREQ broadcast at high power by source RREQ directly reaches more nodes All recipients become candidates to directly offer route to source If necessary, source can move towards node that offers best route

18. MobiQuitous 2004Kimaya Sanzgiri AODV Operation in Example Network C X W V U T S R Q P Y Z Congested Region Regular Transmission Range RREQ RREP

19. MobiQuitous 2004Kimaya Sanzgiri Q-AODV Operation in Example Network C X W V U T S R Q P Y Z Congested Region Regular Transmission Range

20. MobiQuitous 2004Kimaya Sanzgiri MQ-AODV Operation in Example Network C X W V U T S R Q P Y Z Congested Region Increased Transmission Range RREQ RREP

21. MobiQuitous 2004Kimaya Sanzgiri MQ-AODV Details Assumptions Geographical location known Transmission power adjustable No obstacles User defines movement zone Movement zone and regular transmission range together define potential neighbor set

22. MobiQuitous 2004Kimaya Sanzgiri MQ-AODV Details RREQ broadcast by source at increased power Should reach farthest potential neighbor Contains location information of source First hop (potential neighbor) saves location information Regular route discovery procedure followed thereafter (at regular power)

23. MobiQuitous 2004Kimaya Sanzgiri MQ-AODV Details Destination sends RREP Each intermediate node checks whether it is the last hop The last hop Adds its own location information to RREP Looks up saved location information of source Increases transmission power if necessary

24. MobiQuitous 2004Kimaya Sanzgiri MQ-AODV Details On receiving RREP, source checks location information of last hop If necessary, source moves closer to last hop

25. MobiQuitous 2004Kimaya Sanzgiri MQ-AODV Limitations Movement distance limited by maximum transmission power Obstacles not considered Possibility of multiple users moving to same location

26. MobiQuitous 2004Kimaya Sanzgiri Protocol Evaluation Simulation-based (NS-2) 50 nodes in 1000m x 1000m area Regular transmission range = 250m MQ-AODV movement zone radius = 150m Between 2 and 10 application sessions (64 kbps, 180 seconds each)

27. MobiQuitous 2004Kimaya Sanzgiri Application Model Client-server-based streaming media application Implemented by modifying CBR Client initiates session by sending request to server Server streams data at specified rate Retry interval between 10 and 20 seconds

28. MobiQuitous 2004Kimaya Sanzgiri Mobility Pattern Graded mobility 20 nodes static Remaining nodes move based on random waypoint 10 nodes between 0 and 5 m/s 10 nodes between 5 and 10 m/s 10 nodes between 10 and 20 m/s Client and server nodes static

29. MobiQuitous 2004Kimaya Sanzgiri Performance Metrics Packet delivery fraction Number of data packets received End-to-end delay Fraction of received packets with unacceptable end-to-end delay (> 400ms) Routing load

30. MobiQuitous 2004Kimaya Sanzgiri Packet Delivery Fraction

31. MobiQuitous 2004Kimaya Sanzgiri Received Data Packets

32. MobiQuitous 2004Kimaya Sanzgiri End-to-End Delay

33. MobiQuitous 2004Kimaya Sanzgiri Delayed Packets

34. MobiQuitous 2004Kimaya Sanzgiri Routing Load

35. MobiQuitous 2004Kimaya Sanzgiri Performance Results MQ-AODV gives better packet delivery fraction, throughput, end-to-end delay and routing load as compared to Q-AODV AODV performs poorly due to lack of admission control

36. MobiQuitous 2004Kimaya Sanzgiri Conclusion Leveraging mobility does improve quality of service Future work: Address limitations of MQ-AODV Extend other QoS routing protocols

37. MobiQuitous 2004Kimaya Sanzgiri Thank You! Questions/Comments?