22. A Performance Comparison of Multi-Hop Wireless Ad hoc Network Routing Protocols

This paper describes a wireless networks without fixed access points. This point-to-point connection is commonly refered to as ad hoc network. Four design choices were compared, namelyu, DSDV, TORA, DSR, and AODV. An extended version of ns-2 network simulator was used to test these different designs.

Each node in this infrastructureless network is linked by a single physical channel, and the power level where the packet was received is compared to two values,

sent to MAC layer

------------------ value 1) carrier sense threshould

packet error

------------------ value 2) receive threshould

noise

Distributed Coordination Function (DCF) is implemented to model the medium access control. it is similar to MACA and MACAW which use physical carrier sense and virtual carrier sense to reduce collisions.

Four protocols compared through topology change, see how packets react to it:

• Destination-Sequenced Distance Vector (DSDV): hop-by-hop distance vector. All nodes broadcast routing updates.
• Temporally-Ordered Routing Algorithm (TORA): "link reversal" discover routes on demind, sometimes longer routes are used to avoid discovering new routes.
• Dynamic Source Routing (DSR): complete list of nodes it passes through
• Ad Hoc On-Demand Distance Vector (AODV): combination of DSR and DSDV. combines 1) DSR: route discovery and route maintenance; 2)DSDV: hop-by-hop routing, sequence #s, perodic beacons