1. 2005/02/171 A Region-Based Routing Protocol for Wireless Mobile Ad Hoc Networks Speaker: Chen-Nien Tsai Adviser: Kai-Wei Ke

2. 2005/02/172 Outline Introduction Region-Based Routing (REGR) Protocol Route Creation Protocol Route Update Protocol Simulation Results Conclusions

3. 2005/02/173 Introduction Routing Protocols for mobile ad hoc networks are responsible for establishing low-cost, high quality routes. To avoid huge route maintenance cost, various on-demand routing protocols have been proposed. Flooding-based route discovery is widely assumed in existing on-demand routing protocols.

4. 2005/02/174 Flooding-based Route Discovery SourceDestination (a)(b)

5. 2005/02/175 Flooding-based Route Discovery (cont.) It enables the discovery of optimal routes from sources to destinations. All nodes are required to relay the route request (RREQ) packets. Therefore, substantial control overhead is inevitable. Nodes located outside the region between source-destination pair waste their power to rebroadcast the RREQs.  how to improve it?

6. 2005/02/176 Region-based Routing (REGR) Dynamically establish a prerouting region between source and destination pair. Limit the propagations of RREQ packets only within the prerouting region. Can find the optimal or near-optimal routes. Consequently Route construction overhead reduced. Route optimality is also guaranteed.

7. 2005/02/177 REGR (cont.) Region-based route creation protocol to handle new route formation cases. Region-based route update protocol to handle route reconstruction cases.

8. 2005/02/178 Route Creation Protocol Route creation process consists of 3 stages: Destination Discovery build a preliminary route (shortest route) from source to destination. Formation of the Prerouting Region Prerouting region is formed in the neighborhood of the preliminary route. In-Region Route Discovery The optimal route within the region can always be detected.

9. 2005/02/179 Route Creation Protocol Destination Discovery The source first broadcasting a destination location (DLOC) packet. It utilize the distance-based backoff scheme to define the rebroadcast defer time. Ideally, only the border nodes of the DLOC sender need to rebroadcast the DLOC packet. All nodes relaying the DLOC have to create a backward routing entry for the source.

10. 2005/02/1710 Route Creation Protocol Destination Discovery (cont.)

11. 2005/02/1711 Route Creation Protocol Prerouting Region Formation The destination selects the shortest route and names it preliminary route. In this stage, it establish a prerouting region in the neighborhood of the preliminary route. In wireless networks the shortest route in many cases is no longer the optimal one. Although the preliminary route may not be the optimal route, it is a good direction indicator.

12. 2005/02/1712 Route Creation Protocol Prerouting Region Formation (cont.) The optimal route or near-optimal routes very likely lie in the prerouting region. After choosing a preliminary route, the destination broadcasts a region definition (RDEF) packet. All nodes receiving the RDEF mark themselves as in-region nodes. REGION-WIDTH is a value to name the size of the prerouting region.

13. 2005/02/1713 Route Creation Protocol Prerouting Region Formation (cont.) REGION_WIDTH = 1

14. 2005/02/1714 Route Creation Protocol In-Region Route Discovery The destination broadcasts an RREQ a short period after it releases the RDEF. Only nodes with in-region marks participate in rebroadcast of the RREQ. REGR makes intermediate nodes relay the duplicated RREQs if they are transmitted from better routes. (unlike AODV) The optimal route within the region can always be detected.

15. 2005/02/1715 Route Creation Protocol In-Region Route Discovery (cont.)

16. 2005/02/1716 Route Update Protocol Node mobility and power depletion may lead to breakage of existing routes. A route update process is needed for these cases to repair problematic routes. This process can skip the destination discovery stage since the old route is a good preliminary route.

17. 2005/02/1717 Route Update Protocol Prerouting Region Formation Route-update source (RU-SRC) initiates the process by broadcasting an RDEF. The broken points of the route may block propagation of the RDEF. An efficient solution is to enlarge the prerouting region only at problematic spots. Route-clear timer RDEF_ACK

18. 2005/02/1718 Route Update Protocol Prerouting Region Formation (cont.)

19. 2005/02/1719 Route Update Protocol In-Region Route Discovery The RU-SRC sends an RREQ a short period after it releases the RDEF. Upon receiving the RREQs, the route update destination (RU-DEST) selects the best route and return a route confirmation packet.

20. 2005/02/1720 Simulation Results Simulation environment IEEE 802.11 model. Nodes are randomly placed in the network. Nodes have the same transmission range: 250m. Initial power of each node: 25J. Node transmitting power: 0.66W. Node receiving power: 0.395W. Node idling power: 0.035W. Each source sends out 5 packets per second. Data packet size: 2048 bits RREQ and DLOC share the same size: 192 bits RDEF packet size: 160 bits Channel capacity: 1 MB/s

21. 2005/02/1721 Performance of the REGR Route Creation Protocol Routing overhead MBCR (Minimum Battery Cost Routing) AODV (Ad hoc On- demand Distance Vector routing) REGR (Region-Based Routing)

22. 2005/02/1722 Performance of the REGR Route Creation Protocol (cont.) Residual power variance is calculated among all nodes every 20s to measure the network-wide energy balancing. MBCR always searches the whole network for the optimal routes.

23. 2005/02/1723 Performance of the REGR Route Update Protocol QL (Query Localization) Very small routing overhead, but nodes quickly deplete their batteries.

24. 2005/02/1724 Conclusions Introduce a region-based routing protocol. It limit route discovery activities within a predefined region. Not only routing overhead is low, but good route quality is also ensured. Simulation results show that REGR is extremely efficient in large, dense, highly dynamic networks.

25. 2005/02/1725 Reference Yong Lin, Xuhui Hu, Myung J. Lee and Tarek N. Saadawi, “A Region-Based Routing Protocol for Wireless Mobile Ad Hoc Networks,” IEEE Network, vol. 18, no. 4, Jul 2004, pp. 12 – 17.

26. 2005/02/1726 The End