A Survey of Routing Protocols that Support Qos in Mobile Ad Hoc Networks

1. A Survey of Routing Protocols that Support Qos in Mobile Ad Hoc Networks Lei Chen and Wendi B. Heinzelman , University of Rochester IEEE Network. November/December 2007. Presented by Pei-Wei Li

2. Authors • Wendi B. Heinzelman received Ph.D. degree in electrical engineering and computer science from MIT in 2000. • She is an associate professor in the Department of Electrical and Computer Engineering at the University of Rochester, New York. • Lei Chen received Ph.D. degree in electrical and computer engineering from the University of Rochester in 2006.

3. Introduction • The explosive growth in the use of mobile devices and users’ desires for real-time application has provided new challenges in the design of protocols. • A routing protocol incorporating Qos is required.

4. Outline • Characteristics of MANET • Basic design considerations for a Qos-aware routing Protocol • Qos-aware Routing Protocols • Routing Protocol Performance Comparison • Open Issues in Qos-aware Routing

5. Characteristics of MANET • Physical characteristics: wireless channels cause unpredictable bandwidth and delay. • Organizational format: the distributed nature means that resource cannot be allocated in a pre-determined way. • Dynamic topology: hosts are mobile, links are created and destroyed in an unpredictable way.

6. Basic design considerations for a Qos-aware Routing Protocol • Resource estimation • Route discovery : Reactive/Proactive • Resource reservation • Route maintenance • Route selection

7. Qos-aware Routing Protocol-Core-Extraction Distributed Ad Hoc Routing (CEDAR) • CEDAR establishes a core set for route set up. • Corenodes exchanges bandwidth information by disseminating increase waves and decrease waves. • Resource estimation: MAC/link layer can estimate available link bandwidth.

8. Qos-aware Routing Protocol-Core-Extraction Distributed Ad Hoc Routing (CEDAR) • Core Broadcast (based on RTS-CTS)

9. Qos-aware Routing Protocol-Core-Extraction Distributed Ad Hoc Routing (CEDAR) • Route discovery: (1)Establishment of Core Path --The dominator of the source initiates a core broadcast. --The core hosts who relay this broadcast attach their IDs in the packet. --The dominator of the destination sends a ack to the dominator of the source.

10. Qos-aware Routing Protocol-Core-Extraction Distributed Ad Hoc Routing (CEDAR) (2)Qos Route Computation: The source dominator tries to find a route that guarantees the required bandwidth according the core path. • Route maintenance: source or intermediate core node can initiate a route re-computation. Source destination T dom(s) dom(d) dom(T)

11. Qos-aware Routing Protocol-Ticket-based Qos Routing • Resource estimation: Bandwidth/delay information can be obtained from lower layers. • Route discovery: Tickets are used to find bandwidth/delay constrained routes. • Route selection: The route with the lowest cost will be selected as primary route.

12. Qos-aware Routing Protocol-Ticket-based Qos Routing • Resource reservation: The nodes will lock the corresponding resources when they receive a reply from destination. • Route maintenance: The host that discovers a route break searches for a local repair.

13. Qos-aware Routing Protocol-Ad Hoc Qos On-demand Routing (AQOR) • Resource estimation: --Available bandwidth estimation is according to the sum of the neighbors’ traffic information. --One way end-to-end delay estimation is round trip delay.

14. Qos-aware Routing Protocol-Ad Hoc Qos On-demand Routing (AQOR) • Route discovery --The source broadcasts a route request. --The intermediate hosts check their available bandwidth. --Upon receiving each request packet, the destination will send back a reply packet. • Route selection: Source chooses the first in-time reply as route.

15. Qos-aware Routing Protocol-Ad Hoc Qos On-demand Routing (AQOR) • Resource reservation: It is activated while the data flow passes the node along the selected route. The node only reserve resource for a certain time interval. • Route maintenance: --neighbor lost detection: source initiate rerouting. --Qos violation and reservation timeout: destination triggers route recovery.

16. Qos-aware Routing Protocol-Trigger-based Distributed-Qos Routing (TDR) • A location-based routing protocol using -local neighbor database -activity-based database • Resource estimation: Bandwidth information can be obtained from lower layers.

17. Qos-aware Routing Protocol-Trigger-based Distributed-Qos Routing (TDR) • Route discovery: -selective forwarding: only neighbors who receive the route discovery packet with power greater than a certain threshold are considered as possible links in the route. -intermediate hosts check whether their residual bandwidth is sufficient to meet the request. -loop-free routing: intermediate nodes accept the route discovery packet only once for a particular session.

18. Qos-aware Routing Protocol-Trigger-based Distributed-Qos Routing (TDR) • Resource reservation: The nodes reserve resource for a certain time interval when receiving request and update available resource when receiving a ack message. • Route maintenance: using three different receive-power levels(Pth1>Pth2>Pcr) to predict route breaks.

19. Qos-aware Routing Protocol-Adaptive Qos Routing Algorithm (ADQR) • Using three different received signal strength to predict route breaks and define nodes , links , routes. • Resource estimation: Bandwidth information can be obtained from lower layers.

20. Qos-aware Routing Protocol-Adaptive Qos Routing Algorithm (ADQR) • Route discovery:

21. Qos-aware Routing Protocol-Adaptive Qos Routing Algorithm (ADQR) • Route selection: routes with strong signal strength links have the highest selection priority. • Resource reservation: Source sends Qos_Reservepacket to perform bandwidth reservation. • Route maintenance: two-phase monitored rerouting composed ofPre_Reroutingand Rerouting.

22. Qos-aware Routing Protocol-Qos-aware Routing Based on Bandwidth Estimation (BEQR) • Resource estimation: --Listen bandwidth estimation --Hello bandwidth estimation • Route maintenance: The host who cannot receive a Hello message from a downlink neighbor will send a error message to source.

23. Qos-aware Routing Protocol-Qos-aware Routing Based on Bandwidth Estimation (BEQR) • Route discovery: --call admission: flow contention (i.e., inter-flow interference) is considered. --adaptive feedback: flow self-contention (i.e., intra-flow interference) is considered.

24. Routing Protocol Performance Comparison

25. Routing Protocol Performance Comparison • Scalability --when node mobility is high: ticket-based Qos-aware routing will scale well. --when traffic density is high: ticket-based Qos-aware routing and CEDAR will scale well.

26. Open Issues in Qos-aware Routing • Bandwidth/delay estimation: What is the best way to estimate available bandwidth and/or delay to maximize accuracy and minimize overhead for resource estimation?

27. Open Issues in Qos-aware Routing • Route Discovery: Which class of routing protocols, reactive or proactive, is better for supporting Qos routing to balance overhead and delay?

28. Open Issues in Qos-aware Routing • Resource Reservation: How should in-band signaling be coupled with the routing protocol for resource reservation?

29. Open Issues in Qos-aware Routing • Route maintenance: How should the prediction of route breaks, route redundancy, and rerouting optimization be incorporated into a rerouting scheme to balance overhead with Qos performance?

30. Open Issues in Qos-aware Routing • Cross-layer design: What types of information should be shared among the layers to best support Qos-aware routing in MANET?

31. Thanks for your listening!