The twin objectives of DMEF are to discover stable routes with a reduced energy consumption compared to that incurred using flooding.
To discover stable routes that exist for a longer time, DMEF adopts the following approach: A node that is highly mobile makes itself available only to a smaller neighbourhood around itself, whereas a node that is less mobile makes itself available over a larger neighbourhood (but still contained within the complete neighbourhood).
DMEF effectively uses the knowledge of neighbourhood node density and mobility so that they complement each other in discovering stable routes in a more energy-efficient fashion.
The specialty of DMEF is that it allows for each node to dynamically and independently choose at run-time the appropriate values for the critical operating parameters [alpha] and [beta] depending on the perceived number of nodes in the complete neighbourhood of the node and the node's own velocity.
In this section, we discuss the working of the MANET multicast routing protocols (MAODV, BEMRP, NR-MLPBR and R-MLPBR) whose performance under DMEF and default flooding is studied through simulations in this paper.
The broadcast tree discovery strategies simulated are the default flooding approach and DMEF. The DMEF parameter values are given in Table 1.
Performance with DMEF as the Tree Discovery Strategy
Thus, DMEF can yield multicast trees with reduced number of links in low node mobility, especially for multicast groups of small and moderate sizes.
In the case of DMEF, the hop count per source-receiver path for BEMRP can be as large as 36%, 49% and 53% more than that of the hop count per source-receiver path incurred for the other three multicast routing protocols.
This shows that DMEF can yield multicast trees with reduced hop count per source-receiver path under low node mobility, especially for multicast groups of small and moderate sizes.
On the other hand, when we employ DMEF, R-MLPBR tends to incur larger time between successive broadcast tree discoveries compared to BEMRP, even for larger group sizes.
In each instance, the increase in the time between successive route discoveries while using DMEF is at least 10-15% more than that obtained due to flooding.