Improved vertical handover decision algorithm using ants' colonies with adaptive pheromone evaporation rate for 4th generation heterogeneous wireless networks

Abstract

ACOR (Ant Colony Optimisation for Continuous Domains) has been proved to be able to adapt to vertical handoff mechanism. Adaptation capabilities of ACO are due to the pheromone evaporation, where the rate is usually fixed as it is done for vertical handover decision algorithm using ant colonies for 4G heterogeneous wireless networks. An adaptive pheromone evaporation rate (PER) is more suitable. High PER will eliminate the high intensity of pheromone trails that represent bad solutions from previous environments, while low PER may be more interesting when we have stagnation behaviours to minimise power consumption. In this paper, an update version of vertical handover decision algorithm using ant colonies for 4G heterogeneous wireless networks is proposed to vary the evaporation rate at different stages of the optimisation process. Simulation results show that ACOR with adaptive pheromone evaporation rate (ACOR APER) achieves promising results, when compared to the original ACOR and ACOR LPER (ACOR with low pheromone evaporation rate) with a fixed pheromone evaporation rate.