ROUTING IN MOBILE AD-HOC NETWORKS Le Nam Thang Wang Xun Sriram Krishnamoorthy

Problem Definition Determination and management of routes between nodes in the adhoc network.

Solution characteristics Different metrics to optimize Should address frequent changes in : Topology Traffic Patterns, etc. Handle any system characteristics such as unidirectional links. Should address trade-off between latency in determining a route and the overhead of route management (control traffic and state).

Routing metrics Route length (#hops) Signal stability (SSR) Freshness of route (AODV) Association stability (ABR)

Classification Ad hoc routing protocols Flat routing Hierarchical routing Geographical position Augmented routing Proactive Reactive CGSR HSR Proactive Reactive AODV DSR LAR DSDV WRP GPSR DREAM

Flat Routing Flat routing protocols assume a flat topology All nodes are equally involved in routing.

Hierarchical Routing Hierarchical routing protocols choose some nodes which act as the backbone of the MANET.

Geography Oriented Routing Uses geographical information (say from GPS) in routing.

Proactive Routing Protocols Maintain data structures which indicate the path to be taken for each destination node (also called table-driven protocols). Keep the data structures up-to-date by periodic exchange of information.

Proactive Routing Protocols Destination Metric Next Hop MH1 2 MH2 1 MH3 MH4 - MH5 MH6 …. Table for node MH4

Reactive Routing Protocols Determine a route to a destination only when a request for transmission to that node arrives (also called on-command or source-initiated protocols). Usually cache newly found routes to minimize the latency involved in route discovery. Involve three phases: Route discovery Route maintenance Route erasure

Reactive Routing Protocols

Extensions Special routing protocols for specific situations Power-aware routing Security issues. Multicast QoS support

Problems Making explicit the trade-off between latency and state to maintain.