RAT selection for multiple calls in heterogeneous wireless networks using modified topsis group decision making technique

Existing radio access technology (RAT)-selection algorithms for heterogeneous wireless networks (HWNs) do not consider the problem of RAT selection for a group of calls from a multimode terminal. Multimode terminals for next generation wireless networks have the capability to support two or more classes of calls simultaneously. The problem of RAT selection for a group calls occurs in a HWN when a single RAT is to be selected for multiple classes of calls initiated from a multimode terminal, or when multiple classes of calls are to be handed over from one RAT to another. This paper addresses the problem of RAT selection for a group of calls in HWNs by using the modified TOPSIS group decision making technique. The paper proposes a RAT-selection algorithm that selects the most suitable RAT for a group of different classes of calls from a multimode terminal in HWNs. The algorithm considers users´ preferences for individual RATs, which vary with each class of calls, in making RAT selection decisions in HWNs. A user´s preference for each of the available RAT is specified by weights assigned by the user to the different RAT selection criteria for different classes of calls. Based on the assigned weights, the proposed algorithm aggregates individual calls´ weights specified by the user to make a RAT-selection decision for a group of calls. Some numerical examples are given to show the effectiveness of the proposed RAT-selection algorithm.