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

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

3. 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).

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

5. 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

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

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

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

9. 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.

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

11. 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

12. Reactive Routing Protocols

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

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