Routing in Mobile Ad Hoc Networks

1. Routing in Mobile Ad Hoc Networks Marc Heissenbüttel University of Berne http://www.iam.unibe.ch/ Bern, 2001-12-19

2. Table of Contents • Introduction • Proactive Routing Protocols • Reactive Routing Protocols • Further Routing Protocols • Hybrid • GPSR • NCCR-MICS • Conclusion and Outlook

3. Introduction • Infrastructured Networks • Mobile Host communicates with Base Station • Handoff • Drawbacks • deployment of infrastructure, centralized administration, vulnerable • Ad Hoc Networks • autonomous system of mobile routers, connected by wireless links • rapidly deployable, without prior planning or any existing infrastructure • routers are free to move randomly, so topology may change rapidly and unpredictably

4. Routing Protocols • Ad Hoc Routing Protocol requirements • self starting, self organizing • multi-hop, loop free paths • dynamic topology maintenance, rapid convergence • scaleable to large networks, minimal overhead for data transmission • Proactive (table driven) • DSDV, OLSR • Reactive (on demand, source initiated) • DSR, AODV, TORA, ABR, LAR • ZRP (Hybrid), GPSR

5. DSDV (Destination Sequenced Distance Vector) • Based on Bellman-Ford • Route with the most recent Seq. Nr. is always used • Factors to alleviate network traffic • delay of broadcast through settling time • Packets additionally contain a Seq. Nr. unique to the broadcast • Broken Routes: infinite metric, odd Seq. Nr MH1 MH2 MH3 MH4 MH3 Forwarding Table

6. OLSR (Optimized Link State Routing) • Build partial topology, connecting all nodes with subset of all links • Multi Point Relays (MPR) • subset of neighbors, s.t. every two-hop neighbor can be reached • only MPRs retransmit control messages (only information about MPRs) • other nodes only process packet

7. DSR (Dynamic Source Routing) • Source route in packet header, sender transmits packet to first hop • Each mobile host maintains route cache • Host wants to send packet • checks its route cache • route discovery protocol (Host broadcasts route request packet) • Upon receiving route request packet • discard, if already seen, or host’s address listed in the route record • return route (route reply packet), if it is target, or has source route to target • append own address to route record and re-broadcast it • Route reply packet, listing sequence of hops to reach target

8. RREQ RREP RREP RREQ RREQ AODV (Ad Hoc On Demand Distance Vector) • Combination of DSR and DSDV • from DSR: Route discovery, Route maintenance • from DSDV: Hop-by-Hop routing, Seq. Nr. • Route discovery: • Route request: creates a reverse route to source • Route reply: creates a forward route to destination S D S D Reverse Route Forward Route

9. RREQ RREP RREP RREQ RREQ AODV (Ad Hoc On Demand Distance Vector) • Combination of DSR and DSDV • from DSR: Route discovery, Route maintenance • from DSDV: Hop-by-Hop routing, Seq. Nr. • Route discovery: • Route request: creates a reverse route to source • Route reply: creates a forward route to destination Time-out S D S D Reverse Route Forward Route

10. S D TORA (Temporally Ordered Routing Algorithm) • Provides multiple routes • Minimizes algorithm’s reaction • Localization of control messages (close to topological change) • Uses “height” metric to establish DAG • If node other than destination is local minimum • full / partial reversal method

11. TORA (Temporally Ordered Routing Algorithm) • Provides multiple routes • Minimizes algorithm’s reaction • Localization of control messages (close to topological change) • Uses “height” metric to establish DAG • If node other than destination is local minimum • full / partial reversal method S D

12. TORA (Temporally Ordered Routing Algorithm) • Provides multiple routes • Minimizes algorithm’s reaction • Localization of control messages (close to topological change) • Uses “height” metric to establish DAG • If node other than destination is local minimum • full / partial reversal method S D

13. TORA (Temporally Ordered Routing Algorithm) • Provides multiple routes • Minimizes algorithm’s reaction • Localization of control messages (close to topological change) • Uses “height” metric to establish DAG • If node other than destination is local minimum • full / partial reversal method S D

14. ABR (Associativity Based Routing) • New routing metric: Degree of association stability • Nodes periodically generate beacons • Increments associativity tick of current node for beaconing node • Route discovery • similar to DSR, broadcast a BQ (Broadcast Query) • Node receiving BQ, appends its address and its associativity ticks from neighbors • successor node erases associativity tick entries for all nodes, except for itself • Destination select best route • Nodes propagating reply packet mark their routes as valid

15. LAR (Location Aided Routing) • Nodes know their current locations • Source knows Dest. was at location L at time t0 • Expected Zone: Circular region with radius v(t1-t0) centered at L • Request Zone • includes expected zone • Node within request zone forward route request • 1. Rectangle • 2. Distance • Includes distance d to dest. • Next Node only forwards req. , if its distance < d +δ • replaces d with its distance r L Expected Zone I J S Request Zone

16. ZRP (Zone Routing Protocol) • Proactive within routing zone (IARP: IntrAzone Routing Protocol) • Routing zone: min. distance in hops <= zone radius • Reactive for dest. located beyond routing zone (IERP: IntErzone RP) • Bordercast Resolution Protocol (BRP) Zone Radius IERP Peripheral Node Central Node IARP Routing Zone D S BRP BRP BRP IARP

17. y z X D z’ y’ GPSR (Greedy Perimeter Stateless Routing) • No route discovery prior to data transmission • Nodes only know local topology (Beaconing) • Beaconing mechanism to know neighbors’ position • Packet marked with destination’s location • Greedy forwarding • select closest-to-destination neighbor as next hop • Perimeter forwarding • if node is local maximum in proximity • Right-Hand Rule

18. NCCR-MICS • Terminodes • Different viewpoint • wide area • replacing (extending) conventional mobile communication systems • scalability to large numbers (one million nodes!) • incentive to cooperation • Covering different research areas • mathematical aspects • information theoretical question and physical layer • networking • security • applications • ...

19. Packet Forwarding • Two Routing Methods • Terminode Local Routing (TLR) • limited in distance and number of hops (similar to IARP) • Terminode Remote Routing (TRR) • Anchored Geodesic Packet Forwarding (AGPF, similar to LAR) • Friend Assisted Path Discovery (FAPD) • based on small world graphs AP1 AP2 D S

20. Mobility Management: Virtual Home Region • Distribute location information of the nodes in the network • may not be exact, only inside the TLR-Area • in a dynamic, scalable way • Node advertises its position (LDA) to a geographical region (VHR) • fixed center, variable radius • Nodes inside VHRD store location information of D VHRD LDAD S D

21. Mobility Management: Virtual Home Region • Distribute location information of the nodes in the network • may not be exact, only inside the TLR-Area • in a dynamic, scalable way • Node advertises its position (LDA) to a geographical region (VHR) • fixed center, variable radius • Nodes inside VHRD store location information of D VHRD LDAD ? LDAD S D

22. Mobility Management: Virtual Home Region • Distribute location information of the nodes in the network • may not be exact, only inside the TLR-Area • in a dynamic, scalable way • Node advertises its position (LDA) to a geographical region (VHR) • fixed center, variable radius • Nodes inside VHRD store location information of D VHRD LDAD LDAD S D

23. Conclusions and Outlook

24. ? “Ant-Algorithms” Conclusions and Outlook • Nodes are willing to forward packets • Diameter of the network is small • Multi-path forwarding -> improving reliability, stability • Load Balancing • Symmetrical Links are not required • Support of real-time applications