Vertical Handover Decision Algorithm Using Ants’ Colonies for 4G Heterogeneous Wireless Networks

Table 1

Parameters used in the performance evaluation.

Parameter	Symbol	Value
WLAN radius		150 m
Handover delay from cellular network to WLAN		2 S
Handover delay from WLAN to cellular network		2 S
Tolerable handover failure probability		0.005
Tolerable unnecessary handover probability		0.005
Pheromone evaporation rate		0.85
Number of parameters		5
Archive solution size		From 10 to 100
Number of MTs		From 10 to 100
Factor of high importance level		0.8
Factor of medium importance level		0.4
Factor of low importance level		0.2
Number of high importance levels designated by the user		2 (bandwidth, monetary cost)
Number of medium importance levels designated by the user		2 (security, RSS)
Number of nonimportance levels designated by the user		1 (power consumption)