2.3 Least Cost Opportunistic Routing
In the above analysis, we assume the node location information is known and make opportunistic routing decision locally. Next, we introduce least cost opportunistic routing and two polynomial time distributed algorithms to compute the end-to-end opportunistic paths that achieve the least cost. First, we introduce the metric of Expected Opportunistic Transmission Count (EOTX).
2.3.1 Expected Opportunistic Transmission Count (EOTX)
The expected opportunistic transmission count is proposed in Dubois-Ferriere et al. (2007). It is a generalization of the ETX metric in traditional routing (Couto et al. 2003). For a node ni and its forwarding candidate set , the EOTX is defined in Equation (2.15).
where has the same definition in Equation (2.13). The physical meaning of is the probability of at least one forwarding candidate receiving the packet correctly sent by ni per transmission. So the EOTX is the expected number of transmissions necessary for at least one candidate in correctly receiving the packet transmitted by ni.
2.3.2 End-to-end Cost of ...