1. Routing in Mobile Ad-hoc Networks
6 April 2019
Routing in Mobile Ad-hoc Networks
EECS 4215

2. Mobile Ad hoc Networks (MANETs)
No infrastructure (no base stations or access points)
Mobile nodes
Form a network in an ad-hoc manner
Act both as hosts and routers
Communicate using single or multi-hop wireless links
Topology, locations, connectivity, transmission quality are variable.

3. MANETs: Operations X D D Y X Z S S

4. MANETs vs. WMNs Supporting end-user applications
One type of radio on devices
Supporting end-user applications

5. MANETs vs. WMNs (2)
MANETs: end-user devices also perform routing and configuration functionalities for all other nodes.
WMNs: mesh routers perform these tasks.
Mesh routers vs. mobile devices:
power and resource constraints
mobility
MANETs: usually only one radio.
WMNs: can have multiple channels, multiple radios.

6. MANETs: Applications Civil Military Disaster recovery Taxi cabs
Communications over water using floats
Vehicular ad-hoc network
Military
Battlefield communications
Monitoring and planning

7. MANETs: Challenges Wireless channels: error-prone media
Low bandwidth channels
Security
Unpredictable mobility
Devices: low power, limited resources
Maintaining connectivity, states

8. Routing: Wired vs. Wireless
Ad-hoc networks have dynamic time-dependent topology
Links (edges) added/deleted
Nodes (vertices) added/deleted
Bi-directional or uni-directional links
Wireless medium
Inherently a broadcast medium
Fading, shadowing cause burst errors and/or intermittent connectivity
Network topology changes frequently
Low bandwidth: routing protocols must minimize the amount of control traffic generated.

9. Routing Approaches On-demand (reactive) Proactive (table-driven)
acquiring & maintaining routes on demand
DSR (Dynamic Source Routing), AODV (Ad-hoc On-demand Distance Vector)
Proactive (table-driven)
All nodes maintain routes to all destinations in the network at all times.
OLSR (Optimized Link State Routing)
Hybrid: combines reactive and proactive
Zone Routing Protocol (ZPR)
Zone-based Hierarchical Link Sate (ZHLS)

10. Unicast Routing Protocol for MANETs (topology-based)
Table-Driven/
Proactive
Hybrid
On-Demand/
Reactive
Clusterbased/
Hierarchical
Distance-
Vector
Link-
State
ZRP
DSR
AODV
TORA
LANMAR
CEDAR
DSDV
OLSR
TBRPF
FSR
STAR

11. AODV Notes
AODV uses a mechanism similar to distance vector routing  routing loops (e.g., due to “counting to infinity” problem).
AODV uses destination sequence numbers to ensure loop- freedom at all times.
AODV maintains (caches) forward and reverse routes (and sub-routes) as DSR.
Difference from DSR: routing entries are associated with DSNs (“side effect” of DSNs: help avoid obsolete routes)
Route caching speeds up route discovery, minimize control traffic overhead, minimize delay.
Reverse routes can be used for future data packets going in that direction (if the routes are still valid).