Decision-making models for group vertical handover in vehicular communications

In vehicular communications across composite radio environments, the one prominent feature is network heterogeneity, which means that diverse radio access networks co-exist with each other. And another particular feature is group mobility, because multiple mobile equipments in the vehicle are moving at the same time. Therefore, with movement of vehicle, many mobile terminals (MTs) in a train or bus may operate vertical handover actions almost at the same time, which is regarded as the group vertical handover (GVHO). However, the current literatures on vertical handover (VHO) mainly focus on when to trigger handover and how to select the best target network for single user, if these VHO schemes were applied in vehicular communication scenario, it may lead to system performance degradation or network congestion, because the MTs with these VHO decision-making methods selfishly select the best networks regardless of the influences from other concurrent VHO users. Therefore, in order to provide reliable QoS guarantee and keep service connectivity for group mobility in vehicular communications across heterogeneous networks, three models are proposed in this paper to deal with the decision-making problems of incomplete and inaccurate information in GVHO scenario. Two of them adopt MT controlled VHO, while another adopts network assisted VHO. The performances of these schemes are studied with regard to the average transmission delay and average packet losses rate.