Routing in Mobile Ad Hoc Networks Marc Heissenbüttel University of Berne Bern,

Table of Contents  Introduction  Proactive Routing Protocols  Reactive Routing Protocols  Further Routing Protocols  Hybrid  GPSR  NCCR-MICS  Conclusion and Outlook

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

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

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 MH3 Forwarding Table MH1MH2 MH4MH3

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

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

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 RREQ S D RREP Reverse Route Forward Route 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 RREQ S D RREP Reverse Route Forward Route RREQ Time-out

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

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

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

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

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

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 S L r Expected Zone Request Zone I J

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) Central Node Zone Radius Peripheral Node IARP IERP Routing Zone S D BRP IARP BRP

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 X z y D y’ z’

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 ...

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 S D AP1 AP2

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 VHR D store location information of D D S VHR D LDA D

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 VHR D store location information of D D S VHR D LDA D LDA D ?

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 VHR D store location information of D D S VHR D LDA D

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 “Ant-Algorithms” ?