Abstract
Next generation multi-homed terminals designed for heterogeneous wireless network have the capability to simultaneously support two or more different classes of calls on a single or multiple RATs. This paper addresses the problem of optimal RAT selection for a single or multiple handoff calls from a multi-homed terminal in a heterogeneous wireless network where multiple criteria and individual user's preferences are considered in making RAT-selection decisions. The main objective of the optimal RAT-selection algorithm is to select RAT(s) that maximizes a user's RAT preference value (utility) for individual calls in the heterogeneous wireless network. We formulate the problem as a Generalized Assignment optimization problem which attempts to maximize an objective function under the constraints of call QoS requirements and available RAT capacities. The objective function indicates the degree to which a combination of the available RAT(s) matches users' preferred RAT(s) for the individual call(s) to be admitted under the constraint of available resources. Numerical examples are given to show the effectiveness of the proposed scheme.