A Region-Based Routing Protocol for Wireless Mobile Ad Hoc Networks

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

2. Outline • Introduction • Region-Based Routing (REGR) Protocol • Route Creation Protocol • Route Update Protocol • Simulation Results • Conclusions

3. 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. Source Destination (a) (b) Flooding-based Route Discovery

5. 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. 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. REGR (cont.) • Region-based route creation protocol • to handle new route formation cases. • Region-based route update protocol • to handle route reconstruction cases.

8. 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. Route Creation ProtocolDestination 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. Route Creation ProtocolDestination Discovery (cont.)

11. Route Creation ProtocolPrerouting 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. Route Creation ProtocolPrerouting 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-regionnodes. • REGION-WIDTH is a value to name the size of the prerouting region.

13. Route Creation ProtocolPrerouting Region Formation (cont.) REGION_WIDTH = 1

14. Route Creation ProtocolIn-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. Route Creation ProtocolIn-Region Route Discovery (cont.)

16. 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. Route Update ProtocolPrerouting 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. Route Update ProtocolPrerouting Region Formation (cont.)

19. Route Update ProtocolIn-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. 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. 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. 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. Performance of the REGR Route Update Protocol • QL (Query Localization) • Very small routing overhead, but nodes quickly deplete their batteries.

24. 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. 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. The End