RTS/CTS handshake mechanism is especially designed for Ad hoc unicast mode but not for multicast mode.This leads Multicast tree nodes prone to collide with hidden terminal(HT).The

m

-rank collision domain

the distribution of nodes in m-rank collision domain indicators and the concept of nodes-self-distribution optimal tree(NSDOT) are proposed while the collision probability of tree node in the m-rank collision domain is analyzed considering the wireless network data multicast communication mechanism.They are integrated into the design of the multicast tree fitness function to eliminate bad trees and optimize the distribution of tree nodes in the collision domain of rank

m

.A preventive mecha

nism in advance is formed at the network layer

which reduces the collision probability of HT.As an application in MAODV

the simulation results on NS2 show that NSDOT obviously and stably increases the average ratio of data packet delivery.These can also be a valuable reference for the routing node distribution optimization of the mesh-based

the hybrid and the other types MANETs routing protocols.