[Retracted] HGKM: An Efficient Hybrid Group Key Management for Unmanned Autonomous Vehicles MBN in Wireless Network Environment

Table 4

The communication cost of leave operation to HGKM, LKH, and OFT.

Group key management algorithm		Communication cost
HGKM	Situation (i) one member leaves any member unit	2
	Situation (ii) one leader contestant leaves the group	2
	Situation (iii) one leader leaves this group and any leadership contestant is prepared to be the new leader	3
	Situation (iv) one leader leaves a group, also no leadership contestant is available	3
LKH		H
OFT		H

the tallest of that group key tree, which matches , wherever n extends in the whole group.