This paper compares four different routing protocols for ad hoc networks: DSDV, TORA, DSR, and AODV. They extend a simulator to model node mobility, a radio propagation model, radio network interfaces, and MAC DCF (which, like MACA(W) tries to reduce the probability of collisions due to hidden terminals).
DSDV: "hop-by-hop distance vector routing protocol requiring each node to periodically broadcast routing updates." Each node maintains a routing table with info about its neighbors.
TORA: goal is to find routes quickly and react to mobility changes; shortest path routing is secondary to this goal. When a node needs a route, it broadcasts a packet asking for the route which propagates through the network until it reaches the destination or a neighbor of the destination. At that point, the destination/neighbor sends back a packet with a "height" parameter that is incremented as it goes back to the requester.
DSR: source routing, so intermediate nodes don't need to maintain a whole bunch of state. Each packet has all the routing information it needs (this seems like it might be dangerous in a mobile network with rapidly changing topology). For path discovery, route requests are broadcast & the destination responds. Route maintenance occurs periodically to discover broken paths.
AODV: combination of DSR and DSDV. When a node needs a route, it broadcasts a ROUTE REQUEST. Anyone with a path will respond with that route and create a reverse route along the way to connect the two.
Simulation results... (1) Unsurprisingly, mobility impairs the performance of all of the routing protocols. (2) Huge variation between protocols in terms of overhead -- TORA (most) has an order of magnitude more than DSR (least). (3) DSDV does poorly with high rates of mobility when links are broken. (4) Despite its huge overhead, TORA is the most reliable, delivering 90+% of packets.
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