Multipath On-demand Routing
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The Multipath On-demand Routing (MOR) protocol is a protocol to connect nodes in wireless sensor networks. It is an Ad Hoc Routing Protocol which is reactive or on-demand, meaning that it establishes routes as needed. The advantage of this approach is obvious if only a few routes are needed, since the routing overhead is less compared to the proactive approach of establishing routes whether or not they are needed. The disadvantage of on-demand establishment of routes is that connections take more time if the route needs to be established.
MOR lessens the disadvantages of on-demand routing in wireless sensor networks by having the likely targets of communication perform an initial broadcast. This allows all recipients to have a route to these nodes.
The main characteristic distinguishing MOR from other ad-hoc routing protocols is that it maintains multiple routes to each destination, when available, whereas most other such protocols only keep a single route. There are many advantages to having multiple routes when possible, including
- increased reliability
- potentially better load balancing
- more even energy consumption (a consequence of better load balancing)
Each node in MOR remembers all next-hop nodes that are closer to a given destination for which a route exists. It then sends successive packets to each such node in round-robin fashion. If a next-hop node fails to acknowledge a given packet, the retransmission is attempted to another node, again if possible. This allows automatic and graceful recovery from occasional localized congestion as well as longer-term reasons for node unavailability.
